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zig/lib/std/mem.zig

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const std = @import("std.zig");
const builtin = @import("builtin");
const debug = std.debug;
const assert = debug.assert;
const math = std.math;
const mem = @This();
const meta = std.meta;
const trait = meta.trait;
const testing = std.testing;
const Endian = std.builtin.Endian;
const native_endian = builtin.cpu.arch.endian();
/// Compile time known minimum page size.
/// https://github.com/ziglang/zig/issues/4082
pub const page_size = switch (builtin.cpu.arch) {
.wasm32, .wasm64 => 64 * 1024,
.aarch64 => switch (builtin.os.tag) {
.macos, .ios, .watchos, .tvos => 16 * 1024,
else => 4 * 1024,
},
.sparcv9 => 8 * 1024,
else => 4 * 1024,
};
/// The standard library currently thoroughly depends on byte size
/// being 8 bits. (see the use of u8 throughout allocation code as
/// the "byte" type.) Code which depends on this can reference this
/// declaration. If we ever try to port the standard library to a
/// non-8-bit-byte platform, this will allow us to search for things
/// which need to be updated.
pub const byte_size_in_bits = 8;
pub const Allocator = @import("mem/Allocator.zig");
/// Detects and asserts if the std.mem.Allocator interface is violated by the caller
/// or the allocator.
pub fn ValidationAllocator(comptime T: type) type {
return struct {
const Self = @This();
underlying_allocator: T,
pub fn init(underlying_allocator: T) @This() {
return .{
.underlying_allocator = underlying_allocator,
};
}
pub fn allocator(self: *Self) Allocator {
return Allocator.init(self, alloc, resize, free);
}
fn getUnderlyingAllocatorPtr(self: *Self) Allocator {
if (T == Allocator) return self.underlying_allocator;
return self.underlying_allocator.allocator();
}
pub fn alloc(
self: *Self,
n: usize,
ptr_align: u29,
len_align: u29,
ret_addr: usize,
) Allocator.Error![]u8 {
assert(n > 0);
assert(mem.isValidAlign(ptr_align));
if (len_align != 0) {
assert(mem.isAlignedAnyAlign(n, len_align));
assert(n >= len_align);
}
const underlying = self.getUnderlyingAllocatorPtr();
const result = try underlying.rawAlloc(n, ptr_align, len_align, ret_addr);
assert(mem.isAligned(@ptrToInt(result.ptr), ptr_align));
if (len_align == 0) {
assert(result.len == n);
} else {
assert(result.len >= n);
assert(mem.isAlignedAnyAlign(result.len, len_align));
}
return result;
}
pub fn resize(
self: *Self,
buf: []u8,
buf_align: u29,
new_len: usize,
len_align: u29,
ret_addr: usize,
) ?usize {
assert(buf.len > 0);
if (len_align != 0) {
assert(mem.isAlignedAnyAlign(new_len, len_align));
assert(new_len >= len_align);
}
const underlying = self.getUnderlyingAllocatorPtr();
const result = underlying.rawResize(buf, buf_align, new_len, len_align, ret_addr) orelse return null;
if (len_align == 0) {
assert(result == new_len);
} else {
assert(result >= new_len);
assert(mem.isAlignedAnyAlign(result, len_align));
}
return result;
}
pub fn free(
self: *Self,
buf: []u8,
buf_align: u29,
ret_addr: usize,
) void {
_ = self;
_ = buf_align;
_ = ret_addr;
assert(buf.len > 0);
}
pub usingnamespace if (T == Allocator or !@hasDecl(T, "reset")) struct {} else struct {
pub fn reset(self: *Self) void {
self.underlying_allocator.reset();
}
};
};
}
pub fn validationWrap(allocator: anytype) ValidationAllocator(@TypeOf(allocator)) {
return ValidationAllocator(@TypeOf(allocator)).init(allocator);
}
/// An allocator helper function. Adjusts an allocation length satisfy `len_align`.
/// `full_len` should be the full capacity of the allocation which may be greater
/// than the `len` that was requsted. This function should only be used by allocators
/// that are unaffected by `len_align`.
pub fn alignAllocLen(full_len: usize, alloc_len: usize, len_align: u29) usize {
assert(alloc_len > 0);
assert(alloc_len >= len_align);
assert(full_len >= alloc_len);
if (len_align == 0)
return alloc_len;
const adjusted = alignBackwardAnyAlign(full_len, len_align);
assert(adjusted >= alloc_len);
return adjusted;
}
const fail_allocator = Allocator{
.ptr = undefined,
.vtable = &failAllocator_vtable,
};
const failAllocator_vtable = Allocator.VTable{
.alloc = failAllocatorAlloc,
.resize = Allocator.NoResize(anyopaque).noResize,
.free = Allocator.NoOpFree(anyopaque).noOpFree,
};
fn failAllocatorAlloc(_: *anyopaque, n: usize, alignment: u29, len_align: u29, ra: usize) Allocator.Error![]u8 {
_ = n;
_ = alignment;
_ = len_align;
_ = ra;
return error.OutOfMemory;
}
test "Allocator basics" {
try testing.expectError(error.OutOfMemory, fail_allocator.alloc(u8, 1));
try testing.expectError(error.OutOfMemory, fail_allocator.allocSentinel(u8, 1, 0));
}
test "Allocator.resize" {
const primitiveIntTypes = .{
i8,
u8,
i16,
u16,
i32,
u32,
i64,
u64,
i128,
u128,
isize,
usize,
};
inline for (primitiveIntTypes) |T| {
var values = try testing.allocator.alloc(T, 100);
defer testing.allocator.free(values);
for (values) |*v, i| v.* = @intCast(T, i);
values = testing.allocator.resize(values, values.len + 10) orelse return error.OutOfMemory;
try testing.expect(values.len == 110);
}
const primitiveFloatTypes = .{
f16,
f32,
f64,
f128,
};
inline for (primitiveFloatTypes) |T| {
var values = try testing.allocator.alloc(T, 100);
defer testing.allocator.free(values);
for (values) |*v, i| v.* = @intToFloat(T, i);
values = testing.allocator.resize(values, values.len + 10) orelse return error.OutOfMemory;
try testing.expect(values.len == 110);
}
}
/// Copy all of source into dest at position 0.
/// dest.len must be >= source.len.
/// If the slices overlap, dest.ptr must be <= src.ptr.
pub fn copy(comptime T: type, dest: []T, source: []const T) void {
// TODO instead of manually doing this check for the whole array
// and turning off runtime safety, the compiler should detect loops like
// this and automatically omit safety checks for loops
@setRuntimeSafety(false);
assert(dest.len >= source.len);
for (source) |s, i|
dest[i] = s;
}
/// Copy all of source into dest at position 0.
/// dest.len must be >= source.len.
/// If the slices overlap, dest.ptr must be >= src.ptr.
pub fn copyBackwards(comptime T: type, dest: []T, source: []const T) void {
// TODO instead of manually doing this check for the whole array
// and turning off runtime safety, the compiler should detect loops like
// this and automatically omit safety checks for loops
@setRuntimeSafety(false);
assert(dest.len >= source.len);
var i = source.len;
while (i > 0) {
i -= 1;
dest[i] = source[i];
}
}
/// Sets all elements of `dest` to `value`.
pub fn set(comptime T: type, dest: []T, value: T) void {
for (dest) |*d|
d.* = value;
}
/// Generally, Zig users are encouraged to explicitly initialize all fields of a struct explicitly rather than using this function.
/// However, it is recognized that there are sometimes use cases for initializing all fields to a "zero" value. For example, when
/// interfacing with a C API where this practice is more common and relied upon. If you are performing code review and see this
/// function used, examine closely - it may be a code smell.
/// Zero initializes the type.
/// This can be used to zero initialize a any type for which it makes sense. Structs will be initialized recursively.
pub fn zeroes(comptime T: type) T {
switch (@typeInfo(T)) {
.ComptimeInt, .Int, .ComptimeFloat, .Float => {
return @as(T, 0);
},
.Enum, .EnumLiteral => {
return @intToEnum(T, 0);
},
.Void => {
return {};
},
.Bool => {
return false;
},
.Optional, .Null => {
return null;
},
.Struct => |struct_info| {
if (@sizeOf(T) == 0) return T{};
if (comptime meta.containerLayout(T) == .Extern) {
var item: T = undefined;
set(u8, asBytes(&item), 0);
return item;
} else {
var structure: T = undefined;
inline for (struct_info.fields) |field| {
if (!field.is_comptime) {
@field(structure, field.name) = zeroes(@TypeOf(@field(structure, field.name)));
}
}
return structure;
}
},
.Pointer => |ptr_info| {
switch (ptr_info.size) {
.Slice => {
return &[_]ptr_info.child{};
},
.C => {
return null;
},
.One, .Many => {
@compileError("Can't set a non nullable pointer to zero.");
},
}
},
.Array => |info| {
if (info.sentinel) |sentinel_ptr| {
const sentinel = @ptrCast(*const info.child, sentinel_ptr).*;
return [_:sentinel]info.child{zeroes(info.child)} ** info.len;
}
return [_]info.child{zeroes(info.child)} ** info.len;
},
.Vector => |info| {
return @splat(info.len, zeroes(info.child));
},
.Union => |info| {
if (comptime meta.containerLayout(T) == .Extern) {
// The C language specification states that (global) unions
// should be zero initialized to the first named member.
return @unionInit(T, info.fields[0].name, zeroes(info.fields[0].field_type));
}
@compileError("Can't set a " ++ @typeName(T) ++ " to zero.");
},
.ErrorUnion,
.ErrorSet,
.Fn,
.BoundFn,
.Type,
.NoReturn,
.Undefined,
.Opaque,
.Frame,
.AnyFrame,
=> {
@compileError("Can't set a " ++ @typeName(T) ++ " to zero.");
},
}
}
test "zeroes" {
const C_struct = extern struct {
x: u32,
y: u32,
};
var a = zeroes(C_struct);
a.y += 10;
try testing.expect(a.x == 0);
try testing.expect(a.y == 10);
const ZigStruct = struct {
comptime comptime_field: u8 = 5,
integral_types: struct {
integer_0: i0,
integer_8: i8,
integer_16: i16,
integer_32: i32,
integer_64: i64,
integer_128: i128,
unsigned_0: u0,
unsigned_8: u8,
unsigned_16: u16,
unsigned_32: u32,
unsigned_64: u64,
unsigned_128: u128,
float_32: f32,
float_64: f64,
},
pointers: struct {
optional: ?*u8,
c_pointer: [*c]u8,
slice: []u8,
},
array: [2]u32,
vector_u32: meta.Vector(2, u32),
vector_f32: meta.Vector(2, f32),
vector_bool: meta.Vector(2, bool),
optional_int: ?u8,
empty: void,
sentinel: [3:0]u8,
};
const b = zeroes(ZigStruct);
try testing.expectEqual(@as(u8, 5), b.comptime_field);
try testing.expectEqual(@as(i8, 0), b.integral_types.integer_0);
try testing.expectEqual(@as(i8, 0), b.integral_types.integer_8);
try testing.expectEqual(@as(i16, 0), b.integral_types.integer_16);
try testing.expectEqual(@as(i32, 0), b.integral_types.integer_32);
try testing.expectEqual(@as(i64, 0), b.integral_types.integer_64);
try testing.expectEqual(@as(i128, 0), b.integral_types.integer_128);
try testing.expectEqual(@as(u8, 0), b.integral_types.unsigned_0);
try testing.expectEqual(@as(u8, 0), b.integral_types.unsigned_8);
try testing.expectEqual(@as(u16, 0), b.integral_types.unsigned_16);
try testing.expectEqual(@as(u32, 0), b.integral_types.unsigned_32);
try testing.expectEqual(@as(u64, 0), b.integral_types.unsigned_64);
try testing.expectEqual(@as(u128, 0), b.integral_types.unsigned_128);
try testing.expectEqual(@as(f32, 0), b.integral_types.float_32);
try testing.expectEqual(@as(f64, 0), b.integral_types.float_64);
try testing.expectEqual(@as(?*u8, null), b.pointers.optional);
try testing.expectEqual(@as([*c]u8, null), b.pointers.c_pointer);
try testing.expectEqual(@as([]u8, &[_]u8{}), b.pointers.slice);
for (b.array) |e| {
try testing.expectEqual(@as(u32, 0), e);
}
try testing.expectEqual(@splat(2, @as(u32, 0)), b.vector_u32);
try testing.expectEqual(@splat(2, @as(f32, 0.0)), b.vector_f32);
try testing.expectEqual(@splat(2, @as(bool, false)), b.vector_bool);
try testing.expectEqual(@as(?u8, null), b.optional_int);
for (b.sentinel) |e| {
try testing.expectEqual(@as(u8, 0), e);
}
const C_union = extern union {
a: u8,
b: u32,
};
var c = zeroes(C_union);
try testing.expectEqual(@as(u8, 0), c.a);
comptime var comptime_union = zeroes(C_union);
try testing.expectEqual(@as(u8, 0), comptime_union.a);
}
/// Initializes all fields of the struct with their default value, or zero values if no default value is present.
/// If the field is present in the provided initial values, it will have that value instead.
/// Structs are initialized recursively.
pub fn zeroInit(comptime T: type, init: anytype) T {
const Init = @TypeOf(init);
switch (@typeInfo(T)) {
.Struct => |struct_info| {
switch (@typeInfo(Init)) {
.Struct => |init_info| {
var value = std.mem.zeroes(T);
inline for (struct_info.fields) |field| {
if (field.default_value) |default_value_ptr| {
const default_value = @ptrCast(*const field.field_type, default_value_ptr).*;
@field(value, field.name) = default_value;
}
}
if (init_info.is_tuple) {
inline for (init_info.fields) |field, i| {
@field(value, struct_info.fields[i].name) = @field(init, field.name);
}
return value;
}
inline for (init_info.fields) |field| {
if (!@hasField(T, field.name)) {
@compileError("Encountered an initializer for `" ++ field.name ++ "`, but it is not a field of " ++ @typeName(T));
}
switch (@typeInfo(field.field_type)) {
.Struct => {
@field(value, field.name) = zeroInit(field.field_type, @field(init, field.name));
},
else => {
@field(value, field.name) = @field(init, field.name);
},
}
}
return value;
},
else => {
@compileError("The initializer must be a struct");
},
}
},
else => {
@compileError("Can't default init a " ++ @typeName(T));
},
}
}
test "zeroInit" {
const I = struct {
d: f64,
};
const S = struct {
a: u32,
b: ?bool,
c: I,
e: [3]u8,
f: i64 = -1,
};
const s = zeroInit(S, .{
.a = 42,
});
try testing.expectEqual(S{
.a = 42,
.b = null,
.c = .{
.d = 0,
},
.e = [3]u8{ 0, 0, 0 },
.f = -1,
}, s);
const Color = struct {
r: u8,
g: u8,
b: u8,
a: u8,
};
const c = zeroInit(Color, .{ 255, 255 });
try testing.expectEqual(Color{
.r = 255,
.g = 255,
.b = 0,
.a = 0,
}, c);
const Foo = struct {
foo: u8 = 69,
bar: u8,
};
const f = zeroInit(Foo, .{});
try testing.expectEqual(Foo{
.foo = 69,
.bar = 0,
}, f);
const Bar = struct {
foo: u32 = 666,
bar: u32 = 420,
};
const b = zeroInit(Bar, .{69});
try testing.expectEqual(Bar{
.foo = 69,
.bar = 420,
}, b);
}
/// Compares two slices of numbers lexicographically. O(n).
pub fn order(comptime T: type, lhs: []const T, rhs: []const T) math.Order {
const n = math.min(lhs.len, rhs.len);
var i: usize = 0;
while (i < n) : (i += 1) {
switch (math.order(lhs[i], rhs[i])) {
.eq => continue,
.lt => return .lt,
.gt => return .gt,
}
}
return math.order(lhs.len, rhs.len);
}
test "order" {
try testing.expect(order(u8, "abcd", "bee") == .lt);
try testing.expect(order(u8, "abc", "abc") == .eq);
try testing.expect(order(u8, "abc", "abc0") == .lt);
try testing.expect(order(u8, "", "") == .eq);
try testing.expect(order(u8, "", "a") == .lt);
}
/// Returns true if lhs < rhs, false otherwise
pub fn lessThan(comptime T: type, lhs: []const T, rhs: []const T) bool {
return order(T, lhs, rhs) == .lt;
}
test "lessThan" {
try testing.expect(lessThan(u8, "abcd", "bee"));
try testing.expect(!lessThan(u8, "abc", "abc"));
try testing.expect(lessThan(u8, "abc", "abc0"));
try testing.expect(!lessThan(u8, "", ""));
try testing.expect(lessThan(u8, "", "a"));
}
/// Compares two slices and returns whether they are equal.
pub fn eql(comptime T: type, a: []const T, b: []const T) bool {
if (a.len != b.len) return false;
if (a.ptr == b.ptr) return true;
for (a) |item, index| {
if (b[index] != item) return false;
}
return true;
}
/// Compares two slices and returns the index of the first inequality.
/// Returns null if the slices are equal.
pub fn indexOfDiff(comptime T: type, a: []const T, b: []const T) ?usize {
const shortest = math.min(a.len, b.len);
if (a.ptr == b.ptr)
return if (a.len == b.len) null else shortest;
var index: usize = 0;
while (index < shortest) : (index += 1) if (a[index] != b[index]) return index;
return if (a.len == b.len) null else shortest;
}
test "indexOfDiff" {
try testing.expectEqual(indexOfDiff(u8, "one", "one"), null);
try testing.expectEqual(indexOfDiff(u8, "one two", "one"), 3);
try testing.expectEqual(indexOfDiff(u8, "one", "one two"), 3);
try testing.expectEqual(indexOfDiff(u8, "one twx", "one two"), 6);
try testing.expectEqual(indexOfDiff(u8, "xne", "one"), 0);
}
/// Takes a pointer to an array, a sentinel-terminated pointer, or a slice, and
/// returns a slice. If there is a sentinel on the input type, there will be a
/// sentinel on the output type. The constness of the output type matches
/// the constness of the input type. `[*c]` pointers are assumed to be 0-terminated,
/// and assumed to not allow null.
pub fn Span(comptime T: type) type {
switch (@typeInfo(T)) {
.Optional => |optional_info| {
return ?Span(optional_info.child);
},
.Pointer => |ptr_info| {
var new_ptr_info = ptr_info;
switch (ptr_info.size) {
.One => switch (@typeInfo(ptr_info.child)) {
.Array => |info| {
new_ptr_info.child = info.child;
new_ptr_info.sentinel = info.sentinel;
},
else => @compileError("invalid type given to std.mem.Span"),
},
.C => {
new_ptr_info.sentinel = &@as(ptr_info.child, 0);
new_ptr_info.is_allowzero = false;
},
.Many, .Slice => {},
}
new_ptr_info.size = .Slice;
return @Type(.{ .Pointer = new_ptr_info });
},
else => @compileError("invalid type given to std.mem.Span"),
}
}
test "Span" {
try testing.expect(Span(*[5]u16) == []u16);
try testing.expect(Span(?*[5]u16) == ?[]u16);
try testing.expect(Span(*const [5]u16) == []const u16);
try testing.expect(Span(?*const [5]u16) == ?[]const u16);
try testing.expect(Span([]u16) == []u16);
try testing.expect(Span(?[]u16) == ?[]u16);
try testing.expect(Span([]const u8) == []const u8);
try testing.expect(Span(?[]const u8) == ?[]const u8);
try testing.expect(Span([:1]u16) == [:1]u16);
try testing.expect(Span(?[:1]u16) == ?[:1]u16);
try testing.expect(Span([:1]const u8) == [:1]const u8);
try testing.expect(Span(?[:1]const u8) == ?[:1]const u8);
try testing.expect(Span([*:1]u16) == [:1]u16);
try testing.expect(Span(?[*:1]u16) == ?[:1]u16);
try testing.expect(Span([*:1]const u8) == [:1]const u8);
try testing.expect(Span(?[*:1]const u8) == ?[:1]const u8);
try testing.expect(Span([*c]u16) == [:0]u16);
try testing.expect(Span(?[*c]u16) == ?[:0]u16);
try testing.expect(Span([*c]const u8) == [:0]const u8);
try testing.expect(Span(?[*c]const u8) == ?[:0]const u8);
}
/// Takes a pointer to an array, a sentinel-terminated pointer, or a slice, and
/// returns a slice. If there is a sentinel on the input type, there will be a
/// sentinel on the output type. The constness of the output type matches
/// the constness of the input type.
///
/// When there is both a sentinel and an array length or slice length, the
/// length value is used instead of the sentinel.
pub fn span(ptr: anytype) Span(@TypeOf(ptr)) {
if (@typeInfo(@TypeOf(ptr)) == .Optional) {
if (ptr) |non_null| {
return span(non_null);
} else {
return null;
}
}
const Result = Span(@TypeOf(ptr));
const l = len(ptr);
const ptr_info = @typeInfo(Result).Pointer;
if (ptr_info.sentinel) |s_ptr| {
const s = @ptrCast(*const ptr_info.child, s_ptr).*;
return ptr[0..l :s];
} else {
return ptr[0..l];
}
}
test "span" {
var array: [5]u16 = [_]u16{ 1, 2, 3, 4, 5 };
const ptr = @as([*:3]u16, array[0..2 :3]);
try testing.expect(eql(u16, span(ptr), &[_]u16{ 1, 2 }));
try testing.expect(eql(u16, span(&array), &[_]u16{ 1, 2, 3, 4, 5 }));
try testing.expectEqual(@as(?[:0]u16, null), span(@as(?[*:0]u16, null)));
}
pub const spanZ = @compileError("deprecated; use use std.mem.span() or std.mem.sliceTo()");
/// Helper for the return type of sliceTo()
fn SliceTo(comptime T: type, comptime end: meta.Elem(T)) type {
switch (@typeInfo(T)) {
.Optional => |optional_info| {
return ?SliceTo(optional_info.child, end);
},
.Pointer => |ptr_info| {
var new_ptr_info = ptr_info;
new_ptr_info.size = .Slice;
switch (ptr_info.size) {
.One => switch (@typeInfo(ptr_info.child)) {
.Array => |array_info| {
new_ptr_info.child = array_info.child;
// The return type must only be sentinel terminated if we are guaranteed
// to find the value searched for, which is only the case if it matches
// the sentinel of the type passed.
if (array_info.sentinel) |sentinel_ptr| {
const sentinel = @ptrCast(*const array_info.child, sentinel_ptr).*;
if (end == sentinel) {
new_ptr_info.sentinel = &end;
} else {
new_ptr_info.sentinel = null;
}
}
},
else => {},
},
.Many, .Slice => {
// The return type must only be sentinel terminated if we are guaranteed
// to find the value searched for, which is only the case if it matches
// the sentinel of the type passed.
if (ptr_info.sentinel) |sentinel_ptr| {
const sentinel = @ptrCast(*const ptr_info.child, sentinel_ptr).*;
if (end == sentinel) {
new_ptr_info.sentinel = &end;
} else {
new_ptr_info.sentinel = null;
}
}
},
.C => {
new_ptr_info.sentinel = &end;
// C pointers are always allowzero, but we don't want the return type to be.
assert(new_ptr_info.is_allowzero);
new_ptr_info.is_allowzero = false;
},
}
return @Type(.{ .Pointer = new_ptr_info });
},
else => {},
}
@compileError("invalid type given to std.mem.sliceTo: " ++ @typeName(T));
}
/// Takes an array, a pointer to an array, a sentinel-terminated pointer, or a slice and
/// iterates searching for the first occurrence of `end`, returning the scanned slice.
/// If `end` is not found, the full length of the array/slice/sentinel terminated pointer is returned.
/// If the pointer type is sentinel terminated and `end` matches that terminator, the
/// resulting slice is also sentinel terminated.
/// Pointer properties such as mutability and alignment are preserved.
/// C pointers are assumed to be non-null.
pub fn sliceTo(ptr: anytype, comptime end: meta.Elem(@TypeOf(ptr))) SliceTo(@TypeOf(ptr), end) {
if (@typeInfo(@TypeOf(ptr)) == .Optional) {
const non_null = ptr orelse return null;
return sliceTo(non_null, end);
}
const Result = SliceTo(@TypeOf(ptr), end);
const length = lenSliceTo(ptr, end);
const ptr_info = @typeInfo(Result).Pointer;
if (ptr_info.sentinel) |s_ptr| {
const s = @ptrCast(*const ptr_info.child, s_ptr).*;
return ptr[0..length :s];
} else {
return ptr[0..length];
}
}
test "sliceTo" {
try testing.expectEqualSlices(u8, "aoeu", sliceTo("aoeu", 0));
{
var array: [5]u16 = [_]u16{ 1, 2, 3, 4, 5 };
try testing.expectEqualSlices(u16, &array, sliceTo(&array, 0));
try testing.expectEqualSlices(u16, array[0..3], sliceTo(array[0..3], 0));
try testing.expectEqualSlices(u16, array[0..2], sliceTo(&array, 3));
try testing.expectEqualSlices(u16, array[0..2], sliceTo(array[0..3], 3));
const sentinel_ptr = @ptrCast([*:5]u16, &array);
try testing.expectEqualSlices(u16, array[0..2], sliceTo(sentinel_ptr, 3));
try testing.expectEqualSlices(u16, array[0..4], sliceTo(sentinel_ptr, 99));
const optional_sentinel_ptr = @ptrCast(?[*:5]u16, &array);
try testing.expectEqualSlices(u16, array[0..2], sliceTo(optional_sentinel_ptr, 3).?);
try testing.expectEqualSlices(u16, array[0..4], sliceTo(optional_sentinel_ptr, 99).?);
const c_ptr = @as([*c]u16, &array);
try testing.expectEqualSlices(u16, array[0..2], sliceTo(c_ptr, 3));
const slice: []u16 = &array;
try testing.expectEqualSlices(u16, array[0..2], sliceTo(slice, 3));
try testing.expectEqualSlices(u16, &array, sliceTo(slice, 99));
const sentinel_slice: [:5]u16 = array[0..4 :5];
try testing.expectEqualSlices(u16, array[0..2], sliceTo(sentinel_slice, 3));
try testing.expectEqualSlices(u16, array[0..4], sliceTo(sentinel_slice, 99));
}
{
var sentinel_array: [5:0]u16 = [_:0]u16{ 1, 2, 3, 4, 5 };
try testing.expectEqualSlices(u16, sentinel_array[0..2], sliceTo(&sentinel_array, 3));
try testing.expectEqualSlices(u16, &sentinel_array, sliceTo(&sentinel_array, 0));
try testing.expectEqualSlices(u16, &sentinel_array, sliceTo(&sentinel_array, 99));
}
try testing.expectEqual(@as(?[]u8, null), sliceTo(@as(?[]u8, null), 0));
}
/// Private helper for sliceTo(). If you want the length, use sliceTo(foo, x).len
fn lenSliceTo(ptr: anytype, comptime end: meta.Elem(@TypeOf(ptr))) usize {
switch (@typeInfo(@TypeOf(ptr))) {
.Pointer => |ptr_info| switch (ptr_info.size) {
.One => switch (@typeInfo(ptr_info.child)) {
.Array => |array_info| {
if (array_info.sentinel) |sentinel_ptr| {
const sentinel = @ptrCast(*const array_info.child, sentinel_ptr).*;
if (sentinel == end) {
return indexOfSentinel(array_info.child, end, ptr);
}
}
return indexOfScalar(array_info.child, ptr, end) orelse array_info.len;
},
else => {},
},
.Many => if (ptr_info.sentinel) |sentinel_ptr| {
const sentinel = @ptrCast(*const ptr_info.child, sentinel_ptr).*;
// We may be looking for something other than the sentinel,
// but iterating past the sentinel would be a bug so we need
// to check for both.
var i: usize = 0;
while (ptr[i] != end and ptr[i] != sentinel) i += 1;
return i;
},
.C => {
assert(ptr != null);
return indexOfSentinel(ptr_info.child, end, ptr);
},
.Slice => {
if (ptr_info.sentinel) |sentinel_ptr| {
const sentinel = @ptrCast(*const ptr_info.child, sentinel_ptr).*;
if (sentinel == end) {
return indexOfSentinel(ptr_info.child, sentinel, ptr);
}
}
return indexOfScalar(ptr_info.child, ptr, end) orelse ptr.len;
},
},
else => {},
}
@compileError("invalid type given to std.mem.sliceTo: " ++ @typeName(@TypeOf(ptr)));
}
test "lenSliceTo" {
try testing.expect(lenSliceTo("aoeu", 0) == 4);
{
var array: [5]u16 = [_]u16{ 1, 2, 3, 4, 5 };
try testing.expectEqual(@as(usize, 5), lenSliceTo(&array, 0));
try testing.expectEqual(@as(usize, 3), lenSliceTo(array[0..3], 0));
try testing.expectEqual(@as(usize, 2), lenSliceTo(&array, 3));
try testing.expectEqual(@as(usize, 2), lenSliceTo(array[0..3], 3));
const sentinel_ptr = @ptrCast([*:5]u16, &array);
try testing.expectEqual(@as(usize, 2), lenSliceTo(sentinel_ptr, 3));
try testing.expectEqual(@as(usize, 4), lenSliceTo(sentinel_ptr, 99));
const c_ptr = @as([*c]u16, &array);
try testing.expectEqual(@as(usize, 2), lenSliceTo(c_ptr, 3));
const slice: []u16 = &array;
try testing.expectEqual(@as(usize, 2), lenSliceTo(slice, 3));
try testing.expectEqual(@as(usize, 5), lenSliceTo(slice, 99));
const sentinel_slice: [:5]u16 = array[0..4 :5];
try testing.expectEqual(@as(usize, 2), lenSliceTo(sentinel_slice, 3));
try testing.expectEqual(@as(usize, 4), lenSliceTo(sentinel_slice, 99));
}
{
var sentinel_array: [5:0]u16 = [_:0]u16{ 1, 2, 3, 4, 5 };
try testing.expectEqual(@as(usize, 2), lenSliceTo(&sentinel_array, 3));
try testing.expectEqual(@as(usize, 5), lenSliceTo(&sentinel_array, 0));
try testing.expectEqual(@as(usize, 5), lenSliceTo(&sentinel_array, 99));
}
}
/// Takes a pointer to an array, an array, a vector, a sentinel-terminated pointer,
/// a slice or a tuple, and returns the length.
/// In the case of a sentinel-terminated array, it uses the array length.
/// For C pointers it assumes it is a pointer-to-many with a 0 sentinel.
pub fn len(value: anytype) usize {
return switch (@typeInfo(@TypeOf(value))) {
.Array => |info| info.len,
.Vector => |info| info.len,
.Pointer => |info| switch (info.size) {
.One => switch (@typeInfo(info.child)) {
.Array => value.len,
else => @compileError("invalid type given to std.mem.len"),
},
.Many => {
const sentinel_ptr = info.sentinel orelse
@compileError("length of pointer with no sentinel");
const sentinel = @ptrCast(*const info.child, sentinel_ptr).*;
return indexOfSentinel(info.child, sentinel, value);
},
.C => {
assert(value != null);
return indexOfSentinel(info.child, 0, value);
},
.Slice => value.len,
},
.Struct => |info| if (info.is_tuple) {
return info.fields.len;
} else @compileError("invalid type given to std.mem.len"),
else => @compileError("invalid type given to std.mem.len"),
};
}
test "len" {
try testing.expect(len("aoeu") == 4);
{
var array: [5]u16 = [_]u16{ 1, 2, 3, 4, 5 };
try testing.expect(len(&array) == 5);
try testing.expect(len(array[0..3]) == 3);
array[2] = 0;
const ptr = @as([*:0]u16, array[0..2 :0]);
try testing.expect(len(ptr) == 2);
}
{
var array: [5:0]u16 = [_:0]u16{ 1, 2, 3, 4, 5 };
try testing.expect(len(&array) == 5);
array[2] = 0;
try testing.expect(len(&array) == 5);
}
{
const vector: meta.Vector(2, u32) = [2]u32{ 1, 2 };
try testing.expect(len(vector) == 2);
}
{
const tuple = .{ 1, 2 };
try testing.expect(len(tuple) == 2);
try testing.expect(tuple[0] == 1);
}
}
pub const lenZ = @compileError("deprecated; use std.mem.len() or std.mem.sliceTo().len");
pub fn indexOfSentinel(comptime Elem: type, comptime sentinel: Elem, ptr: [*:sentinel]const Elem) usize {
var i: usize = 0;
while (ptr[i] != sentinel) {
i += 1;
}
return i;
}
/// Returns true if all elements in a slice are equal to the scalar value provided
pub fn allEqual(comptime T: type, slice: []const T, scalar: T) bool {
for (slice) |item| {
if (item != scalar) return false;
}
return true;
}
pub const dupe = @compileError("deprecated; use `Allocator.dupe`");
pub const dupeZ = @compileError("deprecated; use `Allocator.dupeZ`");
/// Remove values from the beginning of a slice.
pub fn trimLeft(comptime T: type, slice: []const T, values_to_strip: []const T) []const T {
var begin: usize = 0;
while (begin < slice.len and indexOfScalar(T, values_to_strip, slice[begin]) != null) : (begin += 1) {}
return slice[begin..];
}
/// Remove values from the end of a slice.
pub fn trimRight(comptime T: type, slice: []const T, values_to_strip: []const T) []const T {
var end: usize = slice.len;
while (end > 0 and indexOfScalar(T, values_to_strip, slice[end - 1]) != null) : (end -= 1) {}
return slice[0..end];
}
/// Remove values from the beginning and end of a slice.
pub fn trim(comptime T: type, slice: []const T, values_to_strip: []const T) []const T {
var begin: usize = 0;
var end: usize = slice.len;
while (begin < end and indexOfScalar(T, values_to_strip, slice[begin]) != null) : (begin += 1) {}
while (end > begin and indexOfScalar(T, values_to_strip, slice[end - 1]) != null) : (end -= 1) {}
return slice[begin..end];
}
test "trim" {
try testing.expectEqualSlices(u8, "foo\n ", trimLeft(u8, " foo\n ", " \n"));
try testing.expectEqualSlices(u8, " foo", trimRight(u8, " foo\n ", " \n"));
try testing.expectEqualSlices(u8, "foo", trim(u8, " foo\n ", " \n"));
try testing.expectEqualSlices(u8, "foo", trim(u8, "foo", " \n"));
}
/// Linear search for the index of a scalar value inside a slice.
pub fn indexOfScalar(comptime T: type, slice: []const T, value: T) ?usize {
return indexOfScalarPos(T, slice, 0, value);
}
/// Linear search for the last index of a scalar value inside a slice.
pub fn lastIndexOfScalar(comptime T: type, slice: []const T, value: T) ?usize {
var i: usize = slice.len;
while (i != 0) {
i -= 1;
if (slice[i] == value) return i;
}
return null;
}
pub fn indexOfScalarPos(comptime T: type, slice: []const T, start_index: usize, value: T) ?usize {
var i: usize = start_index;
while (i < slice.len) : (i += 1) {
if (slice[i] == value) return i;
}
return null;
}
pub fn indexOfAny(comptime T: type, slice: []const T, values: []const T) ?usize {
return indexOfAnyPos(T, slice, 0, values);
}
pub fn lastIndexOfAny(comptime T: type, slice: []const T, values: []const T) ?usize {
var i: usize = slice.len;
while (i != 0) {
i -= 1;
for (values) |value| {
if (slice[i] == value) return i;
}
}
return null;
}
pub fn indexOfAnyPos(comptime T: type, slice: []const T, start_index: usize, values: []const T) ?usize {
var i: usize = start_index;
while (i < slice.len) : (i += 1) {
for (values) |value| {
if (slice[i] == value) return i;
}
}
return null;
}
pub fn indexOf(comptime T: type, haystack: []const T, needle: []const T) ?usize {
return indexOfPos(T, haystack, 0, needle);
}
/// Find the index in a slice of a sub-slice, searching from the end backwards.
/// To start looking at a different index, slice the haystack first.
/// Consider using `lastIndexOf` instead of this, which will automatically use a
/// more sophisticated algorithm on larger inputs.
pub fn lastIndexOfLinear(comptime T: type, haystack: []const T, needle: []const T) ?usize {
var i: usize = haystack.len - needle.len;
while (true) : (i -= 1) {
if (mem.eql(T, haystack[i .. i + needle.len], needle)) return i;
if (i == 0) return null;
}
}
/// Consider using `indexOfPos` instead of this, which will automatically use a
/// more sophisticated algorithm on larger inputs.
pub fn indexOfPosLinear(comptime T: type, haystack: []const T, start_index: usize, needle: []const T) ?usize {
var i: usize = start_index;
const end = haystack.len - needle.len;
while (i <= end) : (i += 1) {
if (eql(T, haystack[i .. i + needle.len], needle)) return i;
}
return null;
}
fn boyerMooreHorspoolPreprocessReverse(pattern: []const u8, table: *[256]usize) void {
for (table) |*c| {
c.* = pattern.len;
}
var i: usize = pattern.len - 1;
// The first item is intentionally ignored and the skip size will be pattern.len.
// This is the standard way boyer-moore-horspool is implemented.
while (i > 0) : (i -= 1) {
table[pattern[i]] = i;
}
}
fn boyerMooreHorspoolPreprocess(pattern: []const u8, table: *[256]usize) void {
for (table) |*c| {
c.* = pattern.len;
}
var i: usize = 0;
// The last item is intentionally ignored and the skip size will be pattern.len.
// This is the standard way boyer-moore-horspool is implemented.
while (i < pattern.len - 1) : (i += 1) {
table[pattern[i]] = pattern.len - 1 - i;
}
}
/// Find the index in a slice of a sub-slice, searching from the end backwards.
/// To start looking at a different index, slice the haystack first.
/// Uses the Reverse boyer-moore-horspool algorithm on large inputs;
/// `lastIndexOfLinear` on small inputs.
pub fn lastIndexOf(comptime T: type, haystack: []const T, needle: []const T) ?usize {
if (needle.len > haystack.len) return null;
if (needle.len == 0) return haystack.len;
if (!meta.trait.hasUniqueRepresentation(T) or haystack.len < 52 or needle.len <= 4)
return lastIndexOfLinear(T, haystack, needle);
const haystack_bytes = sliceAsBytes(haystack);
const needle_bytes = sliceAsBytes(needle);
var skip_table: [256]usize = undefined;
boyerMooreHorspoolPreprocessReverse(needle_bytes, skip_table[0..]);
var i: usize = haystack_bytes.len - needle_bytes.len;
while (true) {
if (i % @sizeOf(T) == 0 and mem.eql(u8, haystack_bytes[i .. i + needle_bytes.len], needle_bytes)) {
return @divExact(i, @sizeOf(T));
}
const skip = skip_table[haystack_bytes[i]];
if (skip > i) break;
i -= skip;
}
return null;
}
/// Uses Boyer-moore-horspool algorithm on large inputs; `indexOfPosLinear` on small inputs.
pub fn indexOfPos(comptime T: type, haystack: []const T, start_index: usize, needle: []const T) ?usize {
if (needle.len > haystack.len) return null;
if (needle.len == 0) return start_index;
if (!meta.trait.hasUniqueRepresentation(T) or haystack.len < 52 or needle.len <= 4)
return indexOfPosLinear(T, haystack, start_index, needle);
const haystack_bytes = sliceAsBytes(haystack);
const needle_bytes = sliceAsBytes(needle);
var skip_table: [256]usize = undefined;
boyerMooreHorspoolPreprocess(needle_bytes, skip_table[0..]);
var i: usize = start_index * @sizeOf(T);
while (i <= haystack_bytes.len - needle_bytes.len) {
if (i % @sizeOf(T) == 0 and mem.eql(u8, haystack_bytes[i .. i + needle_bytes.len], needle_bytes)) {
return @divExact(i, @sizeOf(T));
}
i += skip_table[haystack_bytes[i + needle_bytes.len - 1]];
}
return null;
}
test "indexOf" {
try testing.expect(indexOf(u8, "one two three four five six seven eight nine ten eleven", "three four").? == 8);
try testing.expect(lastIndexOf(u8, "one two three four five six seven eight nine ten eleven", "three four").? == 8);
try testing.expect(indexOf(u8, "one two three four five six seven eight nine ten eleven", "two two") == null);
try testing.expect(lastIndexOf(u8, "one two three four five six seven eight nine ten eleven", "two two") == null);
try testing.expect(indexOf(u8, "one two three four five six seven eight nine ten", "").? == 0);
try testing.expect(lastIndexOf(u8, "one two three four five six seven eight nine ten", "").? == 48);
try testing.expect(indexOf(u8, "one two three four", "four").? == 14);
try testing.expect(lastIndexOf(u8, "one two three two four", "two").? == 14);
try testing.expect(indexOf(u8, "one two three four", "gour") == null);
try testing.expect(lastIndexOf(u8, "one two three four", "gour") == null);
try testing.expect(indexOf(u8, "foo", "foo").? == 0);
try testing.expect(lastIndexOf(u8, "foo", "foo").? == 0);
try testing.expect(indexOf(u8, "foo", "fool") == null);
try testing.expect(lastIndexOf(u8, "foo", "lfoo") == null);
try testing.expect(lastIndexOf(u8, "foo", "fool") == null);
try testing.expect(indexOf(u8, "foo foo", "foo").? == 0);
try testing.expect(lastIndexOf(u8, "foo foo", "foo").? == 4);
try testing.expect(lastIndexOfAny(u8, "boo, cat", "abo").? == 6);
try testing.expect(lastIndexOfScalar(u8, "boo", 'o').? == 2);
}
test "indexOf multibyte" {
{
// make haystack and needle long enough to trigger boyer-moore-horspool algorithm
const haystack = [1]u16{0} ** 100 ++ [_]u16{ 0xbbaa, 0xccbb, 0xddcc, 0xeedd, 0xffee, 0x00ff };
const needle = [_]u16{ 0xbbaa, 0xccbb, 0xddcc, 0xeedd, 0xffee };
try testing.expectEqual(indexOfPos(u16, &haystack, 0, &needle), 100);
// check for misaligned false positives (little and big endian)
const needleLE = [_]u16{ 0xbbbb, 0xcccc, 0xdddd, 0xeeee, 0xffff };
try testing.expectEqual(indexOfPos(u16, &haystack, 0, &needleLE), null);
const needleBE = [_]u16{ 0xaacc, 0xbbdd, 0xccee, 0xddff, 0xee00 };
try testing.expectEqual(indexOfPos(u16, &haystack, 0, &needleBE), null);
}
{
// make haystack and needle long enough to trigger boyer-moore-horspool algorithm
const haystack = [_]u16{ 0xbbaa, 0xccbb, 0xddcc, 0xeedd, 0xffee, 0x00ff } ++ [1]u16{0} ** 100;
const needle = [_]u16{ 0xbbaa, 0xccbb, 0xddcc, 0xeedd, 0xffee };
try testing.expectEqual(lastIndexOf(u16, &haystack, &needle), 0);
// check for misaligned false positives (little and big endian)
const needleLE = [_]u16{ 0xbbbb, 0xcccc, 0xdddd, 0xeeee, 0xffff };
try testing.expectEqual(lastIndexOf(u16, &haystack, &needleLE), null);
const needleBE = [_]u16{ 0xaacc, 0xbbdd, 0xccee, 0xddff, 0xee00 };
try testing.expectEqual(lastIndexOf(u16, &haystack, &needleBE), null);
}
}
test "indexOfPos empty needle" {
try testing.expectEqual(indexOfPos(u8, "abracadabra", 5, ""), 5);
}
/// Returns the number of needles inside the haystack
/// needle.len must be > 0
/// does not count overlapping needles
pub fn count(comptime T: type, haystack: []const T, needle: []const T) usize {
assert(needle.len > 0);
var i: usize = 0;
var found: usize = 0;
while (indexOfPos(T, haystack, i, needle)) |idx| {
i = idx + needle.len;
found += 1;
}
return found;
}
test "count" {
try testing.expect(count(u8, "", "h") == 0);
try testing.expect(count(u8, "h", "h") == 1);
try testing.expect(count(u8, "hh", "h") == 2);
try testing.expect(count(u8, "world!", "hello") == 0);
try testing.expect(count(u8, "hello world!", "hello") == 1);
try testing.expect(count(u8, " abcabc abc", "abc") == 3);
try testing.expect(count(u8, "udexdcbvbruhasdrw", "bruh") == 1);
try testing.expect(count(u8, "foo bar", "o bar") == 1);
try testing.expect(count(u8, "foofoofoo", "foo") == 3);
try testing.expect(count(u8, "fffffff", "ff") == 3);
try testing.expect(count(u8, "owowowu", "owowu") == 1);
}
/// Returns true if the haystack contains expected_count or more needles
/// needle.len must be > 0
/// does not count overlapping needles
pub fn containsAtLeast(comptime T: type, haystack: []const T, expected_count: usize, needle: []const T) bool {
assert(needle.len > 0);
if (expected_count == 0) return true;
var i: usize = 0;
var found: usize = 0;
while (indexOfPos(T, haystack, i, needle)) |idx| {
i = idx + needle.len;
found += 1;
if (found == expected_count) return true;
}
return false;
}
test "containsAtLeast" {
try testing.expect(containsAtLeast(u8, "aa", 0, "a"));
try testing.expect(containsAtLeast(u8, "aa", 1, "a"));
try testing.expect(containsAtLeast(u8, "aa", 2, "a"));
try testing.expect(!containsAtLeast(u8, "aa", 3, "a"));
try testing.expect(containsAtLeast(u8, "radaradar", 1, "radar"));
try testing.expect(!containsAtLeast(u8, "radaradar", 2, "radar"));
try testing.expect(containsAtLeast(u8, "radarradaradarradar", 3, "radar"));
try testing.expect(!containsAtLeast(u8, "radarradaradarradar", 4, "radar"));
try testing.expect(containsAtLeast(u8, " radar radar ", 2, "radar"));
try testing.expect(!containsAtLeast(u8, " radar radar ", 3, "radar"));
}
/// Reads an integer from memory with size equal to bytes.len.
/// T specifies the return type, which must be large enough to store
/// the result.
pub fn readVarInt(comptime ReturnType: type, bytes: []const u8, endian: Endian) ReturnType {
var result: ReturnType = 0;
switch (endian) {
.Big => {
for (bytes) |b| {
result = (result << 8) | b;
}
},
.Little => {
const ShiftType = math.Log2Int(ReturnType);
for (bytes) |b, index| {
result = result | (@as(ReturnType, b) << @intCast(ShiftType, index * 8));
}
},
}
return result;
}
/// Reads an integer from memory with bit count specified by T.
/// The bit count of T must be evenly divisible by 8.
/// This function cannot fail and cannot cause undefined behavior.
/// Assumes the endianness of memory is native. This means the function can
/// simply pointer cast memory.
pub fn readIntNative(comptime T: type, bytes: *const [@divExact(@typeInfo(T).Int.bits, 8)]u8) T {
return @ptrCast(*align(1) const T, bytes).*;
}
/// Reads an integer from memory with bit count specified by T.
/// The bit count of T must be evenly divisible by 8.
/// This function cannot fail and cannot cause undefined behavior.
/// Assumes the endianness of memory is foreign, so it must byte-swap.
pub fn readIntForeign(comptime T: type, bytes: *const [@divExact(@typeInfo(T).Int.bits, 8)]u8) T {
return @byteSwap(T, readIntNative(T, bytes));
}
pub const readIntLittle = switch (native_endian) {
.Little => readIntNative,
.Big => readIntForeign,
};
pub const readIntBig = switch (native_endian) {
.Little => readIntForeign,
.Big => readIntNative,
};
/// Asserts that bytes.len >= @typeInfo(T).Int.bits / 8. Reads the integer starting from index 0
/// and ignores extra bytes.
/// The bit count of T must be evenly divisible by 8.
/// Assumes the endianness of memory is native. This means the function can
/// simply pointer cast memory.
pub fn readIntSliceNative(comptime T: type, bytes: []const u8) T {
const n = @divExact(@typeInfo(T).Int.bits, 8);
assert(bytes.len >= n);
return readIntNative(T, bytes[0..n]);
}
/// Asserts that bytes.len >= @typeInfo(T).Int.bits / 8. Reads the integer starting from index 0
/// and ignores extra bytes.
/// The bit count of T must be evenly divisible by 8.
/// Assumes the endianness of memory is foreign, so it must byte-swap.
pub fn readIntSliceForeign(comptime T: type, bytes: []const u8) T {
return @byteSwap(T, readIntSliceNative(T, bytes));
}
pub const readIntSliceLittle = switch (native_endian) {
.Little => readIntSliceNative,
.Big => readIntSliceForeign,
};
pub const readIntSliceBig = switch (native_endian) {
.Little => readIntSliceForeign,
.Big => readIntSliceNative,
};
/// Reads an integer from memory with bit count specified by T.
/// The bit count of T must be evenly divisible by 8.
/// This function cannot fail and cannot cause undefined behavior.
pub fn readInt(comptime T: type, bytes: *const [@divExact(@typeInfo(T).Int.bits, 8)]u8, endian: Endian) T {
if (endian == native_endian) {
return readIntNative(T, bytes);
} else {
return readIntForeign(T, bytes);
}
}
/// Asserts that bytes.len >= @typeInfo(T).Int.bits / 8. Reads the integer starting from index 0
/// and ignores extra bytes.
/// The bit count of T must be evenly divisible by 8.
pub fn readIntSlice(comptime T: type, bytes: []const u8, endian: Endian) T {
const n = @divExact(@typeInfo(T).Int.bits, 8);
assert(bytes.len >= n);
return readInt(T, bytes[0..n], endian);
}
test "comptime read/write int" {
comptime {
var bytes: [2]u8 = undefined;
writeIntLittle(u16, &bytes, 0x1234);
const result = readIntBig(u16, &bytes);
try testing.expect(result == 0x3412);
}
comptime {
var bytes: [2]u8 = undefined;
writeIntBig(u16, &bytes, 0x1234);
const result = readIntLittle(u16, &bytes);
try testing.expect(result == 0x3412);
}
}
test "readIntBig and readIntLittle" {
try testing.expect(readIntSliceBig(u0, &[_]u8{}) == 0x0);
try testing.expect(readIntSliceLittle(u0, &[_]u8{}) == 0x0);
try testing.expect(readIntSliceBig(u8, &[_]u8{0x32}) == 0x32);
try testing.expect(readIntSliceLittle(u8, &[_]u8{0x12}) == 0x12);
try testing.expect(readIntSliceBig(u16, &[_]u8{ 0x12, 0x34 }) == 0x1234);
try testing.expect(readIntSliceLittle(u16, &[_]u8{ 0x12, 0x34 }) == 0x3412);
try testing.expect(readIntSliceBig(u72, &[_]u8{ 0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc, 0xde, 0xf0, 0x24 }) == 0x123456789abcdef024);
try testing.expect(readIntSliceLittle(u72, &[_]u8{ 0xec, 0x10, 0x32, 0x54, 0x76, 0x98, 0xba, 0xdc, 0xfe }) == 0xfedcba9876543210ec);
try testing.expect(readIntSliceBig(i8, &[_]u8{0xff}) == -1);
try testing.expect(readIntSliceLittle(i8, &[_]u8{0xfe}) == -2);
try testing.expect(readIntSliceBig(i16, &[_]u8{ 0xff, 0xfd }) == -3);
try testing.expect(readIntSliceLittle(i16, &[_]u8{ 0xfc, 0xff }) == -4);
}
/// Writes an integer to memory, storing it in twos-complement.
/// This function always succeeds, has defined behavior for all inputs, and
/// accepts any integer bit width.
/// This function stores in native endian, which means it is implemented as a simple
/// memory store.
pub fn writeIntNative(comptime T: type, buf: *[(@typeInfo(T).Int.bits + 7) / 8]u8, value: T) void {
@ptrCast(*align(1) T, buf).* = value;
}
/// Writes an integer to memory, storing it in twos-complement.
/// This function always succeeds, has defined behavior for all inputs, but
/// the integer bit width must be divisible by 8.
/// This function stores in foreign endian, which means it does a @byteSwap first.
pub fn writeIntForeign(comptime T: type, buf: *[@divExact(@typeInfo(T).Int.bits, 8)]u8, value: T) void {
writeIntNative(T, buf, @byteSwap(T, value));
}
pub const writeIntLittle = switch (native_endian) {
.Little => writeIntNative,
.Big => writeIntForeign,
};
pub const writeIntBig = switch (native_endian) {
.Little => writeIntForeign,
.Big => writeIntNative,
};
/// Writes an integer to memory, storing it in twos-complement.
/// This function always succeeds, has defined behavior for all inputs, but
/// the integer bit width must be divisible by 8.
pub fn writeInt(comptime T: type, buffer: *[@divExact(@typeInfo(T).Int.bits, 8)]u8, value: T, endian: Endian) void {
if (endian == native_endian) {
return writeIntNative(T, buffer, value);
} else {
return writeIntForeign(T, buffer, value);
}
}
/// Writes a twos-complement little-endian integer to memory.
/// Asserts that buf.len >= @typeInfo(T).Int.bits / 8.
/// The bit count of T must be divisible by 8.
/// Any extra bytes in buffer after writing the integer are set to zero. To
/// avoid the branch to check for extra buffer bytes, use writeIntLittle
/// instead.
pub fn writeIntSliceLittle(comptime T: type, buffer: []u8, value: T) void {
assert(buffer.len >= @divExact(@typeInfo(T).Int.bits, 8));
if (@typeInfo(T).Int.bits == 0) {
return set(u8, buffer, 0);
} else if (@typeInfo(T).Int.bits == 8) {
set(u8, buffer, 0);
buffer[0] = @bitCast(u8, value);
return;
}
// TODO I want to call writeIntLittle here but comptime eval facilities aren't good enough
const uint = std.meta.Int(.unsigned, @typeInfo(T).Int.bits);
var bits = @bitCast(uint, value);
for (buffer) |*b| {
b.* = @truncate(u8, bits);
bits >>= 8;
}
}
/// Writes a twos-complement big-endian integer to memory.
/// Asserts that buffer.len >= @typeInfo(T).Int.bits / 8.
/// The bit count of T must be divisible by 8.
/// Any extra bytes in buffer before writing the integer are set to zero. To
/// avoid the branch to check for extra buffer bytes, use writeIntBig instead.
pub fn writeIntSliceBig(comptime T: type, buffer: []u8, value: T) void {
assert(buffer.len >= @divExact(@typeInfo(T).Int.bits, 8));
if (@typeInfo(T).Int.bits == 0) {
return set(u8, buffer, 0);
} else if (@typeInfo(T).Int.bits == 8) {
set(u8, buffer, 0);
buffer[buffer.len - 1] = @bitCast(u8, value);
return;
}
// TODO I want to call writeIntBig here but comptime eval facilities aren't good enough
const uint = std.meta.Int(.unsigned, @typeInfo(T).Int.bits);
var bits = @bitCast(uint, value);
var index: usize = buffer.len;
while (index != 0) {
index -= 1;
buffer[index] = @truncate(u8, bits);
bits >>= 8;
}
}
pub const writeIntSliceNative = switch (native_endian) {
.Little => writeIntSliceLittle,
.Big => writeIntSliceBig,
};
pub const writeIntSliceForeign = switch (native_endian) {
.Little => writeIntSliceBig,
.Big => writeIntSliceLittle,
};
/// Writes a twos-complement integer to memory, with the specified endianness.
/// Asserts that buf.len >= @typeInfo(T).Int.bits / 8.
/// The bit count of T must be evenly divisible by 8.
/// Any extra bytes in buffer not part of the integer are set to zero, with
/// respect to endianness. To avoid the branch to check for extra buffer bytes,
/// use writeInt instead.
pub fn writeIntSlice(comptime T: type, buffer: []u8, value: T, endian: Endian) void {
comptime assert(@typeInfo(T).Int.bits % 8 == 0);
return switch (endian) {
.Little => writeIntSliceLittle(T, buffer, value),
.Big => writeIntSliceBig(T, buffer, value),
};
}
test "writeIntBig and writeIntLittle" {
var buf0: [0]u8 = undefined;
var buf1: [1]u8 = undefined;
var buf2: [2]u8 = undefined;
var buf9: [9]u8 = undefined;
writeIntBig(u0, &buf0, 0x0);
try testing.expect(eql(u8, buf0[0..], &[_]u8{}));
writeIntLittle(u0, &buf0, 0x0);
try testing.expect(eql(u8, buf0[0..], &[_]u8{}));
writeIntBig(u8, &buf1, 0x12);
try testing.expect(eql(u8, buf1[0..], &[_]u8{0x12}));
writeIntLittle(u8, &buf1, 0x34);
try testing.expect(eql(u8, buf1[0..], &[_]u8{0x34}));
writeIntBig(u16, &buf2, 0x1234);
try testing.expect(eql(u8, buf2[0..], &[_]u8{ 0x12, 0x34 }));
writeIntLittle(u16, &buf2, 0x5678);
try testing.expect(eql(u8, buf2[0..], &[_]u8{ 0x78, 0x56 }));
writeIntBig(u72, &buf9, 0x123456789abcdef024);
try testing.expect(eql(u8, buf9[0..], &[_]u8{ 0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc, 0xde, 0xf0, 0x24 }));
writeIntLittle(u72, &buf9, 0xfedcba9876543210ec);
try testing.expect(eql(u8, buf9[0..], &[_]u8{ 0xec, 0x10, 0x32, 0x54, 0x76, 0x98, 0xba, 0xdc, 0xfe }));
writeIntBig(i8, &buf1, -1);
try testing.expect(eql(u8, buf1[0..], &[_]u8{0xff}));
writeIntLittle(i8, &buf1, -2);
try testing.expect(eql(u8, buf1[0..], &[_]u8{0xfe}));
writeIntBig(i16, &buf2, -3);
try testing.expect(eql(u8, buf2[0..], &[_]u8{ 0xff, 0xfd }));
writeIntLittle(i16, &buf2, -4);
try testing.expect(eql(u8, buf2[0..], &[_]u8{ 0xfc, 0xff }));
}
/// TODO delete this deprecated declaration after 0.10.0 is released
pub const bswapAllFields = @compileError("bswapAllFields has been renamed to byteSwapAllFields");
/// Swap the byte order of all the members of the fields of a struct
/// (Changing their endianess)
pub fn byteSwapAllFields(comptime S: type, ptr: *S) void {
if (@typeInfo(S) != .Struct) @compileError("byteSwapAllFields expects a struct as the first argument");
inline for (std.meta.fields(S)) |f| {
@field(ptr, f.name) = @byteSwap(f.field_type, @field(ptr, f.name));
}
}
test "byteSwapAllFields" {
const T = extern struct {
f0: u8,
f1: u16,
f2: u32,
};
var s = T{
.f0 = 0x12,
.f1 = 0x1234,
.f2 = 0x12345678,
};
byteSwapAllFields(T, &s);
try std.testing.expectEqual(T{
.f0 = 0x12,
.f1 = 0x3412,
.f2 = 0x78563412,
}, s);
}
/// Returns an iterator that iterates over the slices of `buffer` that are not
/// any of the bytes in `delimiter_bytes`.
/// tokenize(u8, " abc def ghi ", " ")
/// Will return slices for "abc", "def", "ghi", null, in that order.
/// If `buffer` is empty, the iterator will return null.
/// If `delimiter_bytes` does not exist in buffer,
/// the iterator will return `buffer`, null, in that order.
/// See also the related function `split`.
pub fn tokenize(comptime T: type, buffer: []const T, delimiter_bytes: []const T) TokenIterator(T) {
return .{
.index = 0,
.buffer = buffer,
.delimiter_bytes = delimiter_bytes,
};
}
test "tokenize" {
var it = tokenize(u8, " abc def ghi ", " ");
try testing.expect(eql(u8, it.next().?, "abc"));
try testing.expect(eql(u8, it.next().?, "def"));
try testing.expect(eql(u8, it.next().?, "ghi"));
try testing.expect(it.next() == null);
it = tokenize(u8, "..\\bob", "\\");
try testing.expect(eql(u8, it.next().?, ".."));
try testing.expect(eql(u8, "..", "..\\bob"[0..it.index]));
try testing.expect(eql(u8, it.next().?, "bob"));
try testing.expect(it.next() == null);
it = tokenize(u8, "//a/b", "/");
try testing.expect(eql(u8, it.next().?, "a"));
try testing.expect(eql(u8, it.next().?, "b"));
try testing.expect(eql(u8, "//a/b", "//a/b"[0..it.index]));
try testing.expect(it.next() == null);
it = tokenize(u8, "|", "|");
try testing.expect(it.next() == null);
it = tokenize(u8, "", "|");
try testing.expect(it.next() == null);
it = tokenize(u8, "hello", "");
try testing.expect(eql(u8, it.next().?, "hello"));
try testing.expect(it.next() == null);
it = tokenize(u8, "hello", " ");
try testing.expect(eql(u8, it.next().?, "hello"));
try testing.expect(it.next() == null);
var it16 = tokenize(
u16,
std.unicode.utf8ToUtf16LeStringLiteral("hello"),
std.unicode.utf8ToUtf16LeStringLiteral(" "),
);
try testing.expect(eql(u16, it16.next().?, std.unicode.utf8ToUtf16LeStringLiteral("hello")));
try testing.expect(it16.next() == null);
}
test "tokenize (multibyte)" {
var it = tokenize(u8, "a|b,c/d e", " /,|");
try testing.expect(eql(u8, it.next().?, "a"));
try testing.expect(eql(u8, it.next().?, "b"));
try testing.expect(eql(u8, it.next().?, "c"));
try testing.expect(eql(u8, it.next().?, "d"));
try testing.expect(eql(u8, it.next().?, "e"));
try testing.expect(it.next() == null);
var it16 = tokenize(
u16,
std.unicode.utf8ToUtf16LeStringLiteral("a|b,c/d e"),
std.unicode.utf8ToUtf16LeStringLiteral(" /,|"),
);
try testing.expect(eql(u16, it16.next().?, std.unicode.utf8ToUtf16LeStringLiteral("a")));
try testing.expect(eql(u16, it16.next().?, std.unicode.utf8ToUtf16LeStringLiteral("b")));
try testing.expect(eql(u16, it16.next().?, std.unicode.utf8ToUtf16LeStringLiteral("c")));
try testing.expect(eql(u16, it16.next().?, std.unicode.utf8ToUtf16LeStringLiteral("d")));
try testing.expect(eql(u16, it16.next().?, std.unicode.utf8ToUtf16LeStringLiteral("e")));
try testing.expect(it16.next() == null);
}
test "tokenize (reset)" {
var it = tokenize(u8, " abc def ghi ", " ");
try testing.expect(eql(u8, it.next().?, "abc"));
try testing.expect(eql(u8, it.next().?, "def"));
try testing.expect(eql(u8, it.next().?, "ghi"));
it.reset();
try testing.expect(eql(u8, it.next().?, "abc"));
try testing.expect(eql(u8, it.next().?, "def"));
try testing.expect(eql(u8, it.next().?, "ghi"));
try testing.expect(it.next() == null);
}
/// Returns an iterator that iterates over the slices of `buffer` that
/// are separated by bytes in `delimiter`.
/// split(u8, "abc|def||ghi", "|")
/// will return slices for "abc", "def", "", "ghi", null, in that order.
/// If `delimiter` does not exist in buffer,
/// the iterator will return `buffer`, null, in that order.
/// The delimiter length must not be zero.
/// See also the related function `tokenize`.
pub fn split(comptime T: type, buffer: []const T, delimiter: []const T) SplitIterator(T) {
assert(delimiter.len != 0);
return .{
.index = 0,
.buffer = buffer,
.delimiter = delimiter,
};
}
test "split" {
var it = split(u8, "abc|def||ghi", "|");
try testing.expect(eql(u8, it.next().?, "abc"));
try testing.expect(eql(u8, it.next().?, "def"));
try testing.expect(eql(u8, it.next().?, ""));
try testing.expect(eql(u8, it.next().?, "ghi"));
try testing.expect(it.next() == null);
it = split(u8, "", "|");
try testing.expect(eql(u8, it.next().?, ""));
try testing.expect(it.next() == null);
it = split(u8, "|", "|");
try testing.expect(eql(u8, it.next().?, ""));
try testing.expect(eql(u8, it.next().?, ""));
try testing.expect(it.next() == null);
it = split(u8, "hello", " ");
try testing.expect(eql(u8, it.next().?, "hello"));
try testing.expect(it.next() == null);
var it16 = split(
u16,
std.unicode.utf8ToUtf16LeStringLiteral("hello"),
std.unicode.utf8ToUtf16LeStringLiteral(" "),
);
try testing.expect(eql(u16, it16.next().?, std.unicode.utf8ToUtf16LeStringLiteral("hello")));
try testing.expect(it16.next() == null);
}
test "split (multibyte)" {
var it = split(u8, "a, b ,, c, d, e", ", ");
try testing.expect(eql(u8, it.next().?, "a"));
try testing.expect(eql(u8, it.next().?, "b ,"));
try testing.expect(eql(u8, it.next().?, "c"));
try testing.expect(eql(u8, it.next().?, "d"));
try testing.expect(eql(u8, it.next().?, "e"));
try testing.expect(it.next() == null);
var it16 = split(
u16,
std.unicode.utf8ToUtf16LeStringLiteral("a, b ,, c, d, e"),
std.unicode.utf8ToUtf16LeStringLiteral(", "),
);
try testing.expect(eql(u16, it16.next().?, std.unicode.utf8ToUtf16LeStringLiteral("a")));
try testing.expect(eql(u16, it16.next().?, std.unicode.utf8ToUtf16LeStringLiteral("b ,")));
try testing.expect(eql(u16, it16.next().?, std.unicode.utf8ToUtf16LeStringLiteral("c")));
try testing.expect(eql(u16, it16.next().?, std.unicode.utf8ToUtf16LeStringLiteral("d")));
try testing.expect(eql(u16, it16.next().?, std.unicode.utf8ToUtf16LeStringLiteral("e")));
try testing.expect(it16.next() == null);
}
pub fn startsWith(comptime T: type, haystack: []const T, needle: []const T) bool {
return if (needle.len > haystack.len) false else eql(T, haystack[0..needle.len], needle);
}
test "startsWith" {
try testing.expect(startsWith(u8, "Bob", "Bo"));
try testing.expect(!startsWith(u8, "Needle in haystack", "haystack"));
}
pub fn endsWith(comptime T: type, haystack: []const T, needle: []const T) bool {
return if (needle.len > haystack.len) false else eql(T, haystack[haystack.len - needle.len ..], needle);
}
test "endsWith" {
try testing.expect(endsWith(u8, "Needle in haystack", "haystack"));
try testing.expect(!endsWith(u8, "Bob", "Bo"));
}
pub fn TokenIterator(comptime T: type) type {
return struct {
buffer: []const T,
delimiter_bytes: []const T,
index: usize,
const Self = @This();
/// Returns a slice of the next token, or null if tokenization is complete.
pub fn next(self: *Self) ?[]const T {
// move to beginning of token
while (self.index < self.buffer.len and self.isSplitByte(self.buffer[self.index])) : (self.index += 1) {}
const start = self.index;
if (start == self.buffer.len) {
return null;
}
// move to end of token
while (self.index < self.buffer.len and !self.isSplitByte(self.buffer[self.index])) : (self.index += 1) {}
const end = self.index;
return self.buffer[start..end];
}
/// Returns a slice of the remaining bytes. Does not affect iterator state.
pub fn rest(self: Self) []const T {
// move to beginning of token
var index: usize = self.index;
while (index < self.buffer.len and self.isSplitByte(self.buffer[index])) : (index += 1) {}
return self.buffer[index..];
}
/// Resets the iterator to the initial token.
pub fn reset(self: *Self) void {
self.index = 0;
}
fn isSplitByte(self: Self, byte: T) bool {
for (self.delimiter_bytes) |delimiter_byte| {
if (byte == delimiter_byte) {
return true;
}
}
return false;
}
};
}
pub fn SplitIterator(comptime T: type) type {
return struct {
buffer: []const T,
index: ?usize,
delimiter: []const T,
const Self = @This();
/// Returns a slice of the next field, or null if splitting is complete.
pub fn next(self: *Self) ?[]const T {
const start = self.index orelse return null;
const end = if (indexOfPos(T, self.buffer, start, self.delimiter)) |delim_start| blk: {
self.index = delim_start + self.delimiter.len;
break :blk delim_start;
} else blk: {
self.index = null;
break :blk self.buffer.len;
};
return self.buffer[start..end];
}
/// Returns a slice of the remaining bytes. Does not affect iterator state.
pub fn rest(self: Self) []const T {
const end = self.buffer.len;
const start = self.index orelse end;
return self.buffer[start..end];
}
};
}
/// Naively combines a series of slices with a separator.
/// Allocates memory for the result, which must be freed by the caller.
pub fn join(allocator: Allocator, separator: []const u8, slices: []const []const u8) ![]u8 {
return joinMaybeZ(allocator, separator, slices, false);
}
/// Naively combines a series of slices with a separator and null terminator.
/// Allocates memory for the result, which must be freed by the caller.
pub fn joinZ(allocator: Allocator, separator: []const u8, slices: []const []const u8) ![:0]u8 {
const out = try joinMaybeZ(allocator, separator, slices, true);
return out[0 .. out.len - 1 :0];
}
fn joinMaybeZ(allocator: Allocator, separator: []const u8, slices: []const []const u8, zero: bool) ![]u8 {
if (slices.len == 0) return if (zero) try allocator.dupe(u8, &[1]u8{0}) else &[0]u8{};
const total_len = blk: {
var sum: usize = separator.len * (slices.len - 1);
for (slices) |slice| sum += slice.len;
if (zero) sum += 1;
break :blk sum;
};
const buf = try allocator.alloc(u8, total_len);
errdefer allocator.free(buf);
copy(u8, buf, slices[0]);
var buf_index: usize = slices[0].len;
for (slices[1..]) |slice| {
copy(u8, buf[buf_index..], separator);
buf_index += separator.len;
copy(u8, buf[buf_index..], slice);
buf_index += slice.len;
}
if (zero) buf[buf.len - 1] = 0;
// No need for shrink since buf is exactly the correct size.
return buf;
}
test "join" {
{
const str = try join(testing.allocator, ",", &[_][]const u8{});
defer testing.allocator.free(str);
try testing.expect(eql(u8, str, ""));
}
{
const str = try join(testing.allocator, ",", &[_][]const u8{ "a", "b", "c" });
defer testing.allocator.free(str);
try testing.expect(eql(u8, str, "a,b,c"));
}
{
const str = try join(testing.allocator, ",", &[_][]const u8{"a"});
defer testing.allocator.free(str);
try testing.expect(eql(u8, str, "a"));
}
{
const str = try join(testing.allocator, ",", &[_][]const u8{ "a", "", "b", "", "c" });
defer testing.allocator.free(str);
try testing.expect(eql(u8, str, "a,,b,,c"));
}
}
test "joinZ" {
{
const str = try joinZ(testing.allocator, ",", &[_][]const u8{});
defer testing.allocator.free(str);
try testing.expect(eql(u8, str, ""));
try testing.expectEqual(str[str.len], 0);
}
{
const str = try joinZ(testing.allocator, ",", &[_][]const u8{ "a", "b", "c" });
defer testing.allocator.free(str);
try testing.expect(eql(u8, str, "a,b,c"));
try testing.expectEqual(str[str.len], 0);
}
{
const str = try joinZ(testing.allocator, ",", &[_][]const u8{"a"});
defer testing.allocator.free(str);
try testing.expect(eql(u8, str, "a"));
try testing.expectEqual(str[str.len], 0);
}
{
const str = try joinZ(testing.allocator, ",", &[_][]const u8{ "a", "", "b", "", "c" });
defer testing.allocator.free(str);
try testing.expect(eql(u8, str, "a,,b,,c"));
try testing.expectEqual(str[str.len], 0);
}
}
/// Copies each T from slices into a new slice that exactly holds all the elements.
pub fn concat(allocator: Allocator, comptime T: type, slices: []const []const T) ![]T {
if (slices.len == 0) return &[0]T{};
const total_len = blk: {
var sum: usize = 0;
for (slices) |slice| {
sum += slice.len;
}
break :blk sum;
};
const buf = try allocator.alloc(T, total_len);
errdefer allocator.free(buf);
var buf_index: usize = 0;
for (slices) |slice| {
copy(T, buf[buf_index..], slice);
buf_index += slice.len;
}
// No need for shrink since buf is exactly the correct size.
return buf;
}
test "concat" {
{
const str = try concat(testing.allocator, u8, &[_][]const u8{ "abc", "def", "ghi" });
defer testing.allocator.free(str);
try testing.expect(eql(u8, str, "abcdefghi"));
}
{
const str = try concat(testing.allocator, u32, &[_][]const u32{
&[_]u32{ 0, 1 },
&[_]u32{ 2, 3, 4 },
&[_]u32{},
&[_]u32{5},
});
defer testing.allocator.free(str);
try testing.expect(eql(u32, str, &[_]u32{ 0, 1, 2, 3, 4, 5 }));
}
}
test "testStringEquality" {
try testing.expect(eql(u8, "abcd", "abcd"));
try testing.expect(!eql(u8, "abcdef", "abZdef"));
try testing.expect(!eql(u8, "abcdefg", "abcdef"));
}
test "testReadInt" {
try testReadIntImpl();
comptime try testReadIntImpl();
}
fn testReadIntImpl() !void {
{
const bytes = [_]u8{
0x12,
0x34,
0x56,
0x78,
};
try testing.expect(readInt(u32, &bytes, Endian.Big) == 0x12345678);
try testing.expect(readIntBig(u32, &bytes) == 0x12345678);
try testing.expect(readIntBig(i32, &bytes) == 0x12345678);
try testing.expect(readInt(u32, &bytes, Endian.Little) == 0x78563412);
try testing.expect(readIntLittle(u32, &bytes) == 0x78563412);
try testing.expect(readIntLittle(i32, &bytes) == 0x78563412);
}
{
const buf = [_]u8{
0x00,
0x00,
0x12,
0x34,
};
const answer = readInt(u32, &buf, Endian.Big);
try testing.expect(answer == 0x00001234);
}
{
const buf = [_]u8{
0x12,
0x34,
0x00,
0x00,
};
const answer = readInt(u32, &buf, Endian.Little);
try testing.expect(answer == 0x00003412);
}
{
const bytes = [_]u8{
0xff,
0xfe,
};
try testing.expect(readIntBig(u16, &bytes) == 0xfffe);
try testing.expect(readIntBig(i16, &bytes) == -0x0002);
try testing.expect(readIntLittle(u16, &bytes) == 0xfeff);
try testing.expect(readIntLittle(i16, &bytes) == -0x0101);
}
}
test "writeIntSlice" {
try testWriteIntImpl();
comptime try testWriteIntImpl();
}
fn testWriteIntImpl() !void {
var bytes: [8]u8 = undefined;
writeIntSlice(u0, bytes[0..], 0, Endian.Big);
try testing.expect(eql(u8, &bytes, &[_]u8{
0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00,
}));
writeIntSlice(u0, bytes[0..], 0, Endian.Little);
try testing.expect(eql(u8, &bytes, &[_]u8{
0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00,
}));
writeIntSlice(u64, bytes[0..], 0x12345678CAFEBABE, Endian.Big);
try testing.expect(eql(u8, &bytes, &[_]u8{
0x12,
0x34,
0x56,
0x78,
0xCA,
0xFE,
0xBA,
0xBE,
}));
writeIntSlice(u64, bytes[0..], 0xBEBAFECA78563412, Endian.Little);
try testing.expect(eql(u8, &bytes, &[_]u8{
0x12,
0x34,
0x56,
0x78,
0xCA,
0xFE,
0xBA,
0xBE,
}));
writeIntSlice(u32, bytes[0..], 0x12345678, Endian.Big);
try testing.expect(eql(u8, &bytes, &[_]u8{
0x00,
0x00,
0x00,
0x00,
0x12,
0x34,
0x56,
0x78,
}));
writeIntSlice(u32, bytes[0..], 0x78563412, Endian.Little);
try testing.expect(eql(u8, &bytes, &[_]u8{
0x12,
0x34,
0x56,
0x78,
0x00,
0x00,
0x00,
0x00,
}));
writeIntSlice(u16, bytes[0..], 0x1234, Endian.Big);
try testing.expect(eql(u8, &bytes, &[_]u8{
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x12,
0x34,
}));
writeIntSlice(u16, bytes[0..], 0x1234, Endian.Little);
try testing.expect(eql(u8, &bytes, &[_]u8{
0x34,
0x12,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
}));
writeIntSlice(i16, bytes[0..], @as(i16, -21555), Endian.Little);
try testing.expect(eql(u8, &bytes, &[_]u8{
0xCD,
0xAB,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
}));
writeIntSlice(i16, bytes[0..], @as(i16, -21555), Endian.Big);
try testing.expect(eql(u8, &bytes, &[_]u8{
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0xAB,
0xCD,
}));
writeIntSlice(u8, bytes[0..], 0x12, Endian.Big);
try testing.expect(eql(u8, &bytes, &[_]u8{
0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x12,
}));
writeIntSlice(u8, bytes[0..], 0x12, Endian.Little);
try testing.expect(eql(u8, &bytes, &[_]u8{
0x12, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00,
}));
writeIntSlice(i8, bytes[0..], -1, Endian.Big);
try testing.expect(eql(u8, &bytes, &[_]u8{
0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0xff,
}));
writeIntSlice(i8, bytes[0..], -1, Endian.Little);
try testing.expect(eql(u8, &bytes, &[_]u8{
0xff, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00,
}));
}
/// Returns the smallest number in a slice. O(n).
/// `slice` must not be empty.
pub fn min(comptime T: type, slice: []const T) T {
assert(slice.len > 0);
var best = slice[0];
for (slice[1..]) |item| {
best = math.min(best, item);
}
return best;
}
test "min" {
try testing.expectEqual(min(u8, "abcdefg"), 'a');
try testing.expectEqual(min(u8, "bcdefga"), 'a');
try testing.expectEqual(min(u8, "a"), 'a');
}
/// Returns the largest number in a slice. O(n).
/// `slice` must not be empty.
pub fn max(comptime T: type, slice: []const T) T {
assert(slice.len > 0);
var best = slice[0];
for (slice[1..]) |item| {
best = math.max(best, item);
}
return best;
}
test "max" {
try testing.expectEqual(max(u8, "abcdefg"), 'g');
try testing.expectEqual(max(u8, "gabcdef"), 'g');
try testing.expectEqual(max(u8, "g"), 'g');
}
/// Finds the smallest and largest number in a slice. O(n).
/// Returns an anonymous struct with the fields `min` and `max`.
/// `slice` must not be empty.
pub fn minMax(comptime T: type, slice: []const T) struct { min: T, max: T } {
assert(slice.len > 0);
var minVal = slice[0];
var maxVal = slice[0];
for (slice[1..]) |item| {
minVal = math.min(minVal, item);
maxVal = math.max(maxVal, item);
}
return .{ .min = minVal, .max = maxVal };
}
test "minMax" {
try testing.expectEqual(minMax(u8, "abcdefg"), .{ .min = 'a', .max = 'g' });
try testing.expectEqual(minMax(u8, "bcdefga"), .{ .min = 'a', .max = 'g' });
try testing.expectEqual(minMax(u8, "a"), .{ .min = 'a', .max = 'a' });
}
/// Returns the index of the smallest number in a slice. O(n).
/// `slice` must not be empty.
pub fn indexOfMin(comptime T: type, slice: []const T) usize {
assert(slice.len > 0);
var best = slice[0];
var index: usize = 0;
for (slice[1..]) |item, i| {
if (item < best) {
best = item;
index = i + 1;
}
}
return index;
}
test "indexOfMin" {
try testing.expectEqual(indexOfMin(u8, "abcdefg"), 0);
try testing.expectEqual(indexOfMin(u8, "bcdefga"), 6);
try testing.expectEqual(indexOfMin(u8, "a"), 0);
}
/// Returns the index of the largest number in a slice. O(n).
/// `slice` must not be empty.
pub fn indexOfMax(comptime T: type, slice: []const T) usize {
assert(slice.len > 0);
var best = slice[0];
var index: usize = 0;
for (slice[1..]) |item, i| {
if (item > best) {
best = item;
index = i + 1;
}
}
return index;
}
test "indexOfMax" {
try testing.expectEqual(indexOfMax(u8, "abcdefg"), 6);
try testing.expectEqual(indexOfMax(u8, "gabcdef"), 0);
try testing.expectEqual(indexOfMax(u8, "a"), 0);
}
/// Finds the indices of the smallest and largest number in a slice. O(n).
/// Returns an anonymous struct with the fields `index_min` and `index_max`.
/// `slice` must not be empty.
pub fn indexOfMinMax(comptime T: type, slice: []const T) struct { index_min: usize, index_max: usize } {
assert(slice.len > 0);
var minVal = slice[0];
var maxVal = slice[0];
var minIdx: usize = 0;
var maxIdx: usize = 0;
for (slice[1..]) |item, i| {
if (item < minVal) {
minVal = item;
minIdx = i + 1;
}
if (item > maxVal) {
maxVal = item;
maxIdx = i + 1;
}
}
return .{ .index_min = minIdx, .index_max = maxIdx };
}
test "indexOfMinMax" {
try testing.expectEqual(indexOfMinMax(u8, "abcdefg"), .{ .index_min = 0, .index_max = 6 });
try testing.expectEqual(indexOfMinMax(u8, "gabcdef"), .{ .index_min = 1, .index_max = 0 });
try testing.expectEqual(indexOfMinMax(u8, "a"), .{ .index_min = 0, .index_max = 0 });
}
pub fn swap(comptime T: type, a: *T, b: *T) void {
const tmp = a.*;
a.* = b.*;
b.* = tmp;
}
/// In-place order reversal of a slice
pub fn reverse(comptime T: type, items: []T) void {
var i: usize = 0;
const end = items.len / 2;
while (i < end) : (i += 1) {
swap(T, &items[i], &items[items.len - i - 1]);
}
}
test "reverse" {
var arr = [_]i32{ 5, 3, 1, 2, 4 };
reverse(i32, arr[0..]);
try testing.expect(eql(i32, &arr, &[_]i32{ 4, 2, 1, 3, 5 }));
}
/// In-place rotation of the values in an array ([0 1 2 3] becomes [1 2 3 0] if we rotate by 1)
/// Assumes 0 <= amount <= items.len
pub fn rotate(comptime T: type, items: []T, amount: usize) void {
reverse(T, items[0..amount]);
reverse(T, items[amount..]);
reverse(T, items);
}
test "rotate" {
var arr = [_]i32{ 5, 3, 1, 2, 4 };
rotate(i32, arr[0..], 2);
try testing.expect(eql(i32, &arr, &[_]i32{ 1, 2, 4, 5, 3 }));
}
/// Replace needle with replacement as many times as possible, writing to an output buffer which is assumed to be of
/// appropriate size. Use replacementSize to calculate an appropriate buffer size.
/// The needle must not be empty.
pub fn replace(comptime T: type, input: []const T, needle: []const T, replacement: []const T, output: []T) usize {
// Empty needle will loop until output buffer overflows.
assert(needle.len > 0);
var i: usize = 0;
var slide: usize = 0;
var replacements: usize = 0;
while (slide < input.len) {
if (mem.startsWith(T, input[slide..], needle)) {
mem.copy(T, output[i .. i + replacement.len], replacement);
i += replacement.len;
slide += needle.len;
replacements += 1;
} else {
output[i] = input[slide];
i += 1;
slide += 1;
}
}
return replacements;
}
test "replace" {
var output: [29]u8 = undefined;
var replacements = replace(u8, "All your base are belong to us", "base", "Zig", output[0..]);
var expected: []const u8 = "All your Zig are belong to us";
try testing.expect(replacements == 1);
try testing.expectEqualStrings(expected, output[0..expected.len]);
replacements = replace(u8, "Favor reading code over writing code.", "code", "", output[0..]);
expected = "Favor reading over writing .";
try testing.expect(replacements == 2);
try testing.expectEqualStrings(expected, output[0..expected.len]);
// Empty needle is not allowed but input may be empty.
replacements = replace(u8, "", "x", "y", output[0..0]);
expected = "";
try testing.expect(replacements == 0);
try testing.expectEqualStrings(expected, output[0..expected.len]);
// Adjacent replacements.
replacements = replace(u8, "\\n\\n", "\\n", "\n", output[0..]);
expected = "\n\n";
try testing.expect(replacements == 2);
try testing.expectEqualStrings(expected, output[0..expected.len]);
replacements = replace(u8, "abbba", "b", "cd", output[0..]);
expected = "acdcdcda";
try testing.expect(replacements == 3);
try testing.expectEqualStrings(expected, output[0..expected.len]);
}
/// Replace all occurences of `needle` with `replacement`.
pub fn replaceScalar(comptime T: type, slice: []T, needle: T, replacement: T) void {
for (slice) |e, i| {
if (e == needle) {
slice[i] = replacement;
}
}
}
/// Collapse consecutive duplicate elements into one entry.
pub fn collapseRepeatsLen(comptime T: type, slice: []T, elem: T) usize {
if (slice.len == 0) return 0;
var write_idx: usize = 1;
var read_idx: usize = 1;
while (read_idx < slice.len) : (read_idx += 1) {
if (slice[read_idx - 1] != elem or slice[read_idx] != elem) {
slice[write_idx] = slice[read_idx];
write_idx += 1;
}
}
return write_idx;
}
/// Collapse consecutive duplicate elements into one entry.
pub fn collapseRepeats(comptime T: type, slice: []T, elem: T) []T {
return slice[0..collapseRepeatsLen(T, slice, elem)];
}
fn testCollapseRepeats(str: []const u8, elem: u8, expected: []const u8) !void {
const mutable = try std.testing.allocator.dupe(u8, str);
defer std.testing.allocator.free(mutable);
try testing.expect(std.mem.eql(u8, collapseRepeats(u8, mutable, elem), expected));
}
test "collapseRepeats" {
try testCollapseRepeats("", '/', "");
try testCollapseRepeats("a", '/', "a");
try testCollapseRepeats("/", '/', "/");
try testCollapseRepeats("//", '/', "/");
try testCollapseRepeats("/a", '/', "/a");
try testCollapseRepeats("//a", '/', "/a");
try testCollapseRepeats("a/", '/', "a/");
try testCollapseRepeats("a//", '/', "a/");
try testCollapseRepeats("a/a", '/', "a/a");
try testCollapseRepeats("a//a", '/', "a/a");
try testCollapseRepeats("//a///a////", '/', "/a/a/");
}
/// Calculate the size needed in an output buffer to perform a replacement.
/// The needle must not be empty.
pub fn replacementSize(comptime T: type, input: []const T, needle: []const T, replacement: []const T) usize {
// Empty needle will loop forever.
assert(needle.len > 0);
var i: usize = 0;
var size: usize = input.len;
while (i < input.len) {
if (mem.startsWith(T, input[i..], needle)) {
size = size - needle.len + replacement.len;
i += needle.len;
} else {
i += 1;
}
}
return size;
}
test "replacementSize" {
try testing.expect(replacementSize(u8, "All your base are belong to us", "base", "Zig") == 29);
try testing.expect(replacementSize(u8, "Favor reading code over writing code.", "code", "") == 29);
try testing.expect(replacementSize(u8, "Only one obvious way to do things.", "things.", "things in Zig.") == 41);
// Empty needle is not allowed but input may be empty.
try testing.expect(replacementSize(u8, "", "x", "y") == 0);
// Adjacent replacements.
try testing.expect(replacementSize(u8, "\\n\\n", "\\n", "\n") == 2);
try testing.expect(replacementSize(u8, "abbba", "b", "cd") == 8);
}
/// Perform a replacement on an allocated buffer of pre-determined size. Caller must free returned memory.
pub fn replaceOwned(comptime T: type, allocator: Allocator, input: []const T, needle: []const T, replacement: []const T) Allocator.Error![]T {
var output = try allocator.alloc(T, replacementSize(T, input, needle, replacement));
_ = replace(T, input, needle, replacement, output);
return output;
}
test "replaceOwned" {
const gpa = std.testing.allocator;
const base_replace = replaceOwned(u8, gpa, "All your base are belong to us", "base", "Zig") catch @panic("out of memory");
defer gpa.free(base_replace);
try testing.expect(eql(u8, base_replace, "All your Zig are belong to us"));
const zen_replace = replaceOwned(u8, gpa, "Favor reading code over writing code.", " code", "") catch @panic("out of memory");
defer gpa.free(zen_replace);
try testing.expect(eql(u8, zen_replace, "Favor reading over writing."));
}
/// Converts a little-endian integer to host endianness.
pub fn littleToNative(comptime T: type, x: T) T {
return switch (native_endian) {
.Little => x,
.Big => @byteSwap(T, x),
};
}
/// Converts a big-endian integer to host endianness.
pub fn bigToNative(comptime T: type, x: T) T {
return switch (native_endian) {
.Little => @byteSwap(T, x),
.Big => x,
};
}
/// Converts an integer from specified endianness to host endianness.
pub fn toNative(comptime T: type, x: T, endianness_of_x: Endian) T {
return switch (endianness_of_x) {
.Little => littleToNative(T, x),
.Big => bigToNative(T, x),
};
}
/// Converts an integer which has host endianness to the desired endianness.
pub fn nativeTo(comptime T: type, x: T, desired_endianness: Endian) T {
return switch (desired_endianness) {
.Little => nativeToLittle(T, x),
.Big => nativeToBig(T, x),
};
}
/// Converts an integer which has host endianness to little endian.
pub fn nativeToLittle(comptime T: type, x: T) T {
return switch (native_endian) {
.Little => x,
.Big => @byteSwap(T, x),
};
}
/// Converts an integer which has host endianness to big endian.
pub fn nativeToBig(comptime T: type, x: T) T {
return switch (native_endian) {
.Little => @byteSwap(T, x),
.Big => x,
};
}
/// Returns the number of elements that, if added to the given pointer, align it
/// to a multiple of the given quantity, or `null` if one of the following
/// conditions is met:
/// - The aligned pointer would not fit the address space,
/// - The delta required to align the pointer is not a multiple of the pointee's
/// type.
pub fn alignPointerOffset(ptr: anytype, align_to: u29) ?usize {
assert(align_to != 0 and @popCount(u29, align_to) == 1);
const T = @TypeOf(ptr);
const info = @typeInfo(T);
if (info != .Pointer or info.Pointer.size != .Many)
@compileError("expected many item pointer, got " ++ @typeName(T));
// Do nothing if the pointer is already well-aligned.
if (align_to <= info.Pointer.alignment)
return 0;
// Calculate the aligned base address with an eye out for overflow.
const addr = @ptrToInt(ptr);
var new_addr: usize = undefined;
if (@addWithOverflow(usize, addr, align_to - 1, &new_addr)) return null;
new_addr &= ~@as(usize, align_to - 1);
// The delta is expressed in terms of bytes, turn it into a number of child
// type elements.
const delta = new_addr - addr;
const pointee_size = @sizeOf(info.Pointer.child);
if (delta % pointee_size != 0) return null;
return delta / pointee_size;
}
/// Aligns a given pointer value to a specified alignment factor.
/// Returns an aligned pointer or null if one of the following conditions is
/// met:
/// - The aligned pointer would not fit the address space,
/// - The delta required to align the pointer is not a multiple of the pointee's
/// type.
pub fn alignPointer(ptr: anytype, align_to: u29) ?@TypeOf(ptr) {
const adjust_off = alignPointerOffset(ptr, align_to) orelse return null;
const T = @TypeOf(ptr);
// Avoid the use of intToPtr to avoid losing the pointer provenance info.
return @alignCast(@typeInfo(T).Pointer.alignment, ptr + adjust_off);
}
test "alignPointer" {
const S = struct {
fn checkAlign(comptime T: type, base: usize, align_to: u29, expected: usize) !void {
var ptr = @intToPtr(T, base);
var aligned = alignPointer(ptr, align_to);
try testing.expectEqual(expected, @ptrToInt(aligned));
}
};
try S.checkAlign([*]u8, 0x123, 0x200, 0x200);
try S.checkAlign([*]align(4) u8, 0x10, 2, 0x10);
try S.checkAlign([*]u32, 0x10, 2, 0x10);
try S.checkAlign([*]u32, 0x4, 16, 0x10);
// Misaligned.
try S.checkAlign([*]align(1) u32, 0x3, 2, 0);
// Overflow.
try S.checkAlign([*]u32, math.maxInt(usize) - 3, 8, 0);
}
fn CopyPtrAttrs(
comptime source: type,
comptime size: std.builtin.Type.Pointer.Size,
comptime child: type,
) type {
const info = @typeInfo(source).Pointer;
return @Type(.{
.Pointer = .{
.size = size,
.is_const = info.is_const,
.is_volatile = info.is_volatile,
.is_allowzero = info.is_allowzero,
.alignment = info.alignment,
.address_space = info.address_space,
.child = child,
.sentinel = null,
},
});
}
fn AsBytesReturnType(comptime P: type) type {
if (!trait.isSingleItemPtr(P))
@compileError("expected single item pointer, passed " ++ @typeName(P));
const size = @sizeOf(meta.Child(P));
return CopyPtrAttrs(P, .One, [size]u8);
}
/// Given a pointer to a single item, returns a slice of the underlying bytes, preserving pointer attributes.
pub fn asBytes(ptr: anytype) AsBytesReturnType(@TypeOf(ptr)) {
const P = @TypeOf(ptr);
return @ptrCast(AsBytesReturnType(P), ptr);
}
test "asBytes" {
const deadbeef = @as(u32, 0xDEADBEEF);
const deadbeef_bytes = switch (native_endian) {
.Big => "\xDE\xAD\xBE\xEF",
.Little => "\xEF\xBE\xAD\xDE",
};
try testing.expect(eql(u8, asBytes(&deadbeef), deadbeef_bytes));
var codeface = @as(u32, 0xC0DEFACE);
for (asBytes(&codeface).*) |*b|
b.* = 0;
try testing.expect(codeface == 0);
const S = packed struct {
a: u8,
b: u8,
c: u8,
d: u8,
};
const inst = S{
.a = 0xBE,
.b = 0xEF,
.c = 0xDE,
.d = 0xA1,
};
try testing.expect(eql(u8, asBytes(&inst), "\xBE\xEF\xDE\xA1"));
const ZST = struct {};
const zero = ZST{};
try testing.expect(eql(u8, asBytes(&zero), ""));
}
test "asBytes preserves pointer attributes" {
const inArr: u32 align(16) = 0xDEADBEEF;
const inPtr = @ptrCast(*align(16) const volatile u32, &inArr);
const outSlice = asBytes(inPtr);
const in = @typeInfo(@TypeOf(inPtr)).Pointer;
const out = @typeInfo(@TypeOf(outSlice)).Pointer;
try testing.expectEqual(in.is_const, out.is_const);
try testing.expectEqual(in.is_volatile, out.is_volatile);
try testing.expectEqual(in.is_allowzero, out.is_allowzero);
try testing.expectEqual(in.alignment, out.alignment);
}
/// Given any value, returns a copy of its bytes in an array.
pub fn toBytes(value: anytype) [@sizeOf(@TypeOf(value))]u8 {
return asBytes(&value).*;
}
test "toBytes" {
var my_bytes = toBytes(@as(u32, 0x12345678));
switch (native_endian) {
.Big => try testing.expect(eql(u8, &my_bytes, "\x12\x34\x56\x78")),
.Little => try testing.expect(eql(u8, &my_bytes, "\x78\x56\x34\x12")),
}
my_bytes[0] = '\x99';
switch (native_endian) {
.Big => try testing.expect(eql(u8, &my_bytes, "\x99\x34\x56\x78")),
.Little => try testing.expect(eql(u8, &my_bytes, "\x99\x56\x34\x12")),
}
}
fn BytesAsValueReturnType(comptime T: type, comptime B: type) type {
const size = @as(usize, @sizeOf(T));
if (comptime !trait.is(.Pointer)(B) or
(meta.Child(B) != [size]u8 and meta.Child(B) != [size:0]u8))
{
comptime var buf: [100]u8 = undefined;
@compileError(std.fmt.bufPrint(&buf, "expected *[{}]u8, passed " ++ @typeName(B), .{size}) catch unreachable);
}
return CopyPtrAttrs(B, .One, T);
}
/// Given a pointer to an array of bytes, returns a pointer to a value of the specified type
/// backed by those bytes, preserving pointer attributes.
pub fn bytesAsValue(comptime T: type, bytes: anytype) BytesAsValueReturnType(T, @TypeOf(bytes)) {
return @ptrCast(BytesAsValueReturnType(T, @TypeOf(bytes)), bytes);
}
test "bytesAsValue" {
const deadbeef = @as(u32, 0xDEADBEEF);
const deadbeef_bytes = switch (native_endian) {
.Big => "\xDE\xAD\xBE\xEF",
.Little => "\xEF\xBE\xAD\xDE",
};
try testing.expect(deadbeef == bytesAsValue(u32, deadbeef_bytes).*);
var codeface_bytes: [4]u8 = switch (native_endian) {
.Big => "\xC0\xDE\xFA\xCE",
.Little => "\xCE\xFA\xDE\xC0",
}.*;
var codeface = bytesAsValue(u32, &codeface_bytes);
try testing.expect(codeface.* == 0xC0DEFACE);
codeface.* = 0;
for (codeface_bytes) |b|
try testing.expect(b == 0);
const S = packed struct {
a: u8,
b: u8,
c: u8,
d: u8,
};
const inst = S{
.a = 0xBE,
.b = 0xEF,
.c = 0xDE,
.d = 0xA1,
};
const inst_bytes = "\xBE\xEF\xDE\xA1";
const inst2 = bytesAsValue(S, inst_bytes);
try testing.expect(meta.eql(inst, inst2.*));
}
test "bytesAsValue preserves pointer attributes" {
const inArr align(16) = [4]u8{ 0xDE, 0xAD, 0xBE, 0xEF };
const inSlice = @ptrCast(*align(16) const volatile [4]u8, &inArr)[0..];
const outPtr = bytesAsValue(u32, inSlice);
const in = @typeInfo(@TypeOf(inSlice)).Pointer;
const out = @typeInfo(@TypeOf(outPtr)).Pointer;
try testing.expectEqual(in.is_const, out.is_const);
try testing.expectEqual(in.is_volatile, out.is_volatile);
try testing.expectEqual(in.is_allowzero, out.is_allowzero);
try testing.expectEqual(in.alignment, out.alignment);
}
/// Given a pointer to an array of bytes, returns a value of the specified type backed by a
/// copy of those bytes.
pub fn bytesToValue(comptime T: type, bytes: anytype) T {
return bytesAsValue(T, bytes).*;
}
test "bytesToValue" {
const deadbeef_bytes = switch (native_endian) {
.Big => "\xDE\xAD\xBE\xEF",
.Little => "\xEF\xBE\xAD\xDE",
};
const deadbeef = bytesToValue(u32, deadbeef_bytes);
try testing.expect(deadbeef == @as(u32, 0xDEADBEEF));
}
fn BytesAsSliceReturnType(comptime T: type, comptime bytesType: type) type {
if (!(trait.isSlice(bytesType) or trait.isPtrTo(.Array)(bytesType)) or meta.Elem(bytesType) != u8) {
@compileError("expected []u8 or *[_]u8, passed " ++ @typeName(bytesType));
}
if (trait.isPtrTo(.Array)(bytesType) and @typeInfo(meta.Child(bytesType)).Array.len % @sizeOf(T) != 0) {
@compileError("number of bytes in " ++ @typeName(bytesType) ++ " is not divisible by size of " ++ @typeName(T));
}
return CopyPtrAttrs(bytesType, .Slice, T);
}
/// Given a slice of bytes, returns a slice of the specified type
/// backed by those bytes, preserving pointer attributes.
pub fn bytesAsSlice(comptime T: type, bytes: anytype) BytesAsSliceReturnType(T, @TypeOf(bytes)) {
// let's not give an undefined pointer to @ptrCast
// it may be equal to zero and fail a null check
if (bytes.len == 0) {
return &[0]T{};
}
const cast_target = CopyPtrAttrs(@TypeOf(bytes), .Many, T);
return @ptrCast(cast_target, bytes)[0..@divExact(bytes.len, @sizeOf(T))];
}
test "bytesAsSlice" {
{
const bytes = [_]u8{ 0xDE, 0xAD, 0xBE, 0xEF };
const slice = bytesAsSlice(u16, bytes[0..]);
try testing.expect(slice.len == 2);
try testing.expect(bigToNative(u16, slice[0]) == 0xDEAD);
try testing.expect(bigToNative(u16, slice[1]) == 0xBEEF);
}
{
const bytes = [_]u8{ 0xDE, 0xAD, 0xBE, 0xEF };
var runtime_zero: usize = 0;
const slice = bytesAsSlice(u16, bytes[runtime_zero..]);
try testing.expect(slice.len == 2);
try testing.expect(bigToNative(u16, slice[0]) == 0xDEAD);
try testing.expect(bigToNative(u16, slice[1]) == 0xBEEF);
}
}
test "bytesAsSlice keeps pointer alignment" {
{
var bytes = [_]u8{ 0x01, 0x02, 0x03, 0x04 };
const numbers = bytesAsSlice(u32, bytes[0..]);
comptime try testing.expect(@TypeOf(numbers) == []align(@alignOf(@TypeOf(bytes))) u32);
}
{
var bytes = [_]u8{ 0x01, 0x02, 0x03, 0x04 };
var runtime_zero: usize = 0;
const numbers = bytesAsSlice(u32, bytes[runtime_zero..]);
comptime try testing.expect(@TypeOf(numbers) == []align(@alignOf(@TypeOf(bytes))) u32);
}
}
test "bytesAsSlice on a packed struct" {
const F = packed struct {
a: u8,
};
var b = [1]u8{9};
var f = bytesAsSlice(F, &b);
try testing.expect(f[0].a == 9);
}
test "bytesAsSlice with specified alignment" {
var bytes align(4) = [_]u8{
0x33,
0x33,
0x33,
0x33,
};
const slice: []u32 = std.mem.bytesAsSlice(u32, bytes[0..]);
try testing.expect(slice[0] == 0x33333333);
}
test "bytesAsSlice preserves pointer attributes" {
const inArr align(16) = [4]u8{ 0xDE, 0xAD, 0xBE, 0xEF };
const inSlice = @ptrCast(*align(16) const volatile [4]u8, &inArr)[0..];
const outSlice = bytesAsSlice(u16, inSlice);
const in = @typeInfo(@TypeOf(inSlice)).Pointer;
const out = @typeInfo(@TypeOf(outSlice)).Pointer;
try testing.expectEqual(in.is_const, out.is_const);
try testing.expectEqual(in.is_volatile, out.is_volatile);
try testing.expectEqual(in.is_allowzero, out.is_allowzero);
try testing.expectEqual(in.alignment, out.alignment);
}
fn SliceAsBytesReturnType(comptime sliceType: type) type {
if (!trait.isSlice(sliceType) and !trait.isPtrTo(.Array)(sliceType)) {
@compileError("expected []T or *[_]T, passed " ++ @typeName(sliceType));
}
return CopyPtrAttrs(sliceType, .Slice, u8);
}
/// Given a slice, returns a slice of the underlying bytes, preserving pointer attributes.
pub fn sliceAsBytes(slice: anytype) SliceAsBytesReturnType(@TypeOf(slice)) {
const Slice = @TypeOf(slice);
// let's not give an undefined pointer to @ptrCast
// it may be equal to zero and fail a null check
if (slice.len == 0 and comptime meta.sentinel(Slice) == null) {
return &[0]u8{};
}
const cast_target = CopyPtrAttrs(Slice, .Many, u8);
return @ptrCast(cast_target, slice)[0 .. slice.len * @sizeOf(meta.Elem(Slice))];
}
test "sliceAsBytes" {
const bytes = [_]u16{ 0xDEAD, 0xBEEF };
const slice = sliceAsBytes(bytes[0..]);
try testing.expect(slice.len == 4);
try testing.expect(eql(u8, slice, switch (native_endian) {
.Big => "\xDE\xAD\xBE\xEF",
.Little => "\xAD\xDE\xEF\xBE",
}));
}
test "sliceAsBytes with sentinel slice" {
const empty_string: [:0]const u8 = "";
const bytes = sliceAsBytes(empty_string);
try testing.expect(bytes.len == 0);
}
test "sliceAsBytes packed struct at runtime and comptime" {
const Foo = packed struct {
a: u4,
b: u4,
};
const S = struct {
fn doTheTest() !void {
var foo: Foo = undefined;
var slice = sliceAsBytes(@as(*[1]Foo, &foo)[0..1]);
slice[0] = 0x13;
switch (native_endian) {
.Big => {
try testing.expect(foo.a == 0x1);
try testing.expect(foo.b == 0x3);
},
.Little => {
try testing.expect(foo.a == 0x3);
try testing.expect(foo.b == 0x1);
},
}
}
};
try S.doTheTest();
comptime try S.doTheTest();
}
test "sliceAsBytes and bytesAsSlice back" {
try testing.expect(@sizeOf(i32) == 4);
var big_thing_array = [_]i32{ 1, 2, 3, 4 };
const big_thing_slice: []i32 = big_thing_array[0..];
const bytes = sliceAsBytes(big_thing_slice);
try testing.expect(bytes.len == 4 * 4);
bytes[4] = 0;
bytes[5] = 0;
bytes[6] = 0;
bytes[7] = 0;
try testing.expect(big_thing_slice[1] == 0);
const big_thing_again = bytesAsSlice(i32, bytes);
try testing.expect(big_thing_again[2] == 3);
big_thing_again[2] = -1;
try testing.expect(bytes[8] == math.maxInt(u8));
try testing.expect(bytes[9] == math.maxInt(u8));
try testing.expect(bytes[10] == math.maxInt(u8));
try testing.expect(bytes[11] == math.maxInt(u8));
}
test "sliceAsBytes preserves pointer attributes" {
const inArr align(16) = [2]u16{ 0xDEAD, 0xBEEF };
const inSlice = @ptrCast(*align(16) const volatile [2]u16, &inArr)[0..];
const outSlice = sliceAsBytes(inSlice);
const in = @typeInfo(@TypeOf(inSlice)).Pointer;
const out = @typeInfo(@TypeOf(outSlice)).Pointer;
try testing.expectEqual(in.is_const, out.is_const);
try testing.expectEqual(in.is_volatile, out.is_volatile);
try testing.expectEqual(in.is_allowzero, out.is_allowzero);
try testing.expectEqual(in.alignment, out.alignment);
}
/// Round an address up to the nearest aligned address
/// The alignment must be a power of 2 and greater than 0.
pub fn alignForward(addr: usize, alignment: usize) usize {
return alignForwardGeneric(usize, addr, alignment);
}
/// Round an address up to the nearest aligned address
/// The alignment must be a power of 2 and greater than 0.
pub fn alignForwardGeneric(comptime T: type, addr: T, alignment: T) T {
return alignBackwardGeneric(T, addr + (alignment - 1), alignment);
}
/// Force an evaluation of the expression; this tries to prevent
/// the compiler from optimizing the computation away even if the
/// result eventually gets discarded.
pub fn doNotOptimizeAway(val: anytype) void {
asm volatile (""
:
: [val] "rm" (val),
: "memory"
);
}
test "alignForward" {
try testing.expect(alignForward(1, 1) == 1);
try testing.expect(alignForward(2, 1) == 2);
try testing.expect(alignForward(1, 2) == 2);
try testing.expect(alignForward(2, 2) == 2);
try testing.expect(alignForward(3, 2) == 4);
try testing.expect(alignForward(4, 2) == 4);
try testing.expect(alignForward(7, 8) == 8);
try testing.expect(alignForward(8, 8) == 8);
try testing.expect(alignForward(9, 8) == 16);
try testing.expect(alignForward(15, 8) == 16);
try testing.expect(alignForward(16, 8) == 16);
try testing.expect(alignForward(17, 8) == 24);
}
/// Round an address up to the previous aligned address
/// Unlike `alignBackward`, `alignment` can be any positive number, not just a power of 2.
pub fn alignBackwardAnyAlign(i: usize, alignment: usize) usize {
if (@popCount(usize, alignment) == 1)
return alignBackward(i, alignment);
assert(alignment != 0);
return i - @mod(i, alignment);
}
/// Round an address up to the previous aligned address
/// The alignment must be a power of 2 and greater than 0.
pub fn alignBackward(addr: usize, alignment: usize) usize {
return alignBackwardGeneric(usize, addr, alignment);
}
/// Round an address up to the previous aligned address
/// The alignment must be a power of 2 and greater than 0.
pub fn alignBackwardGeneric(comptime T: type, addr: T, alignment: T) T {
assert(@popCount(T, alignment) == 1);
// 000010000 // example alignment
// 000001111 // subtract 1
// 111110000 // binary not
return addr & ~(alignment - 1);
}
/// Returns whether `alignment` is a valid alignment, meaning it is
/// a positive power of 2.
pub fn isValidAlign(alignment: u29) bool {
return @popCount(u29, alignment) == 1;
}
pub fn isAlignedAnyAlign(i: usize, alignment: usize) bool {
if (@popCount(usize, alignment) == 1)
return isAligned(i, alignment);
assert(alignment != 0);
return 0 == @mod(i, alignment);
}
/// Given an address and an alignment, return true if the address is a multiple of the alignment
/// The alignment must be a power of 2 and greater than 0.
pub fn isAligned(addr: usize, alignment: usize) bool {
return isAlignedGeneric(u64, addr, alignment);
}
pub fn isAlignedGeneric(comptime T: type, addr: T, alignment: T) bool {
return alignBackwardGeneric(T, addr, alignment) == addr;
}
test "isAligned" {
try testing.expect(isAligned(0, 4));
try testing.expect(isAligned(1, 1));
try testing.expect(isAligned(2, 1));
try testing.expect(isAligned(2, 2));
try testing.expect(!isAligned(2, 4));
try testing.expect(isAligned(3, 1));
try testing.expect(!isAligned(3, 2));
try testing.expect(!isAligned(3, 4));
try testing.expect(isAligned(4, 4));
try testing.expect(isAligned(4, 2));
try testing.expect(isAligned(4, 1));
try testing.expect(!isAligned(4, 8));
try testing.expect(!isAligned(4, 16));
}
test "freeing empty string with null-terminated sentinel" {
const empty_string = try testing.allocator.dupeZ(u8, "");
testing.allocator.free(empty_string);
}
/// Returns a slice with the given new alignment,
/// all other pointer attributes copied from `AttributeSource`.
fn AlignedSlice(comptime AttributeSource: type, comptime new_alignment: u29) type {
const info = @typeInfo(AttributeSource).Pointer;
return @Type(.{
.Pointer = .{
.size = .Slice,
.is_const = info.is_const,
.is_volatile = info.is_volatile,
.is_allowzero = info.is_allowzero,
.alignment = new_alignment,
.address_space = info.address_space,
.child = info.child,
.sentinel = null,
},
});
}
/// Returns the largest slice in the given bytes that conforms to the new alignment,
/// or `null` if the given bytes contain no conforming address.
pub fn alignInBytes(bytes: []u8, comptime new_alignment: usize) ?[]align(new_alignment) u8 {
const begin_address = @ptrToInt(bytes.ptr);
const end_address = begin_address + bytes.len;
const begin_address_aligned = mem.alignForward(begin_address, new_alignment);
const new_length = std.math.sub(usize, end_address, begin_address_aligned) catch |e| switch (e) {
error.Overflow => return null,
};
const alignment_offset = begin_address_aligned - begin_address;
return @alignCast(new_alignment, bytes[alignment_offset .. alignment_offset + new_length]);
}
/// Returns the largest sub-slice within the given slice that conforms to the new alignment,
/// or `null` if the given slice contains no conforming address.
pub fn alignInSlice(slice: anytype, comptime new_alignment: usize) ?AlignedSlice(@TypeOf(slice), new_alignment) {
const bytes = sliceAsBytes(slice);
const aligned_bytes = alignInBytes(bytes, new_alignment) orelse return null;
const Element = @TypeOf(slice[0]);
const slice_length_bytes = aligned_bytes.len - (aligned_bytes.len % @sizeOf(Element));
const aligned_slice = bytesAsSlice(Element, aligned_bytes[0..slice_length_bytes]);
return @alignCast(new_alignment, aligned_slice);
}
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