zig/lib/std/unicode.zig
Andrew Kelley 377e8579f9 std.zig.tokenizer: simplify
I pointed a fuzzer at the tokenizer and it crashed immediately. Upon
inspection, I was dissatisfied with the implementation. This commit
removes several mechanisms:
* Removes the "invalid byte" compile error note.
* Dramatically simplifies tokenizer recovery by making recovery always
  occur at newlines, and never otherwise.
* Removes UTF-8 validation.
* Moves some character validation logic to `std.zig.parseCharLiteral`.

Removing UTF-8 validation is a regression of #663, however, the existing
implementation was already buggy. When adding this functionality back,
it must be fuzz-tested while checking the property that it matches an
independent Unicode validation implementation on the same file. While
we're at it, fuzzing should check the other properties of that proposal,
such as no ASCII control characters existing inside the source code.

Other changes included in this commit:

* Deprecate `std.unicode.utf8Decode` and its WTF-8 counterpart. This
  function has an awkward API that is too easy to misuse.
* Make `utf8Decode2` and friends use arrays as parameters, eliminating a
  runtime assertion in favor of using the type system.

After this commit, the crash found by fuzzing, which was
"\x07\xd5\x80\xc3=o\xda|a\xfc{\x9a\xec\x91\xdf\x0f\\\x1a^\xbe;\x8c\xbf\xee\xea"
no longer causes a crash. However, I did not feel the need to add this
test case because the simplified logic eradicates most crashes of this
nature.
2024-07-31 16:57:42 -07:00

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const std = @import("./std.zig");
const builtin = @import("builtin");
const assert = std.debug.assert;
const testing = std.testing;
const mem = std.mem;
const native_endian = builtin.cpu.arch.endian();
/// Use this to replace an unknown, unrecognized, or unrepresentable character.
///
/// See also: https://en.wikipedia.org/wiki/Specials_(Unicode_block)#Replacement_character
pub const replacement_character: u21 = 0xFFFD;
/// Returns how many bytes the UTF-8 representation would require
/// for the given codepoint.
pub fn utf8CodepointSequenceLength(c: u21) !u3 {
if (c < 0x80) return @as(u3, 1);
if (c < 0x800) return @as(u3, 2);
if (c < 0x10000) return @as(u3, 3);
if (c < 0x110000) return @as(u3, 4);
return error.CodepointTooLarge;
}
/// Given the first byte of a UTF-8 codepoint,
/// returns a number 1-4 indicating the total length of the codepoint in bytes.
/// If this byte does not match the form of a UTF-8 start byte, returns Utf8InvalidStartByte.
pub fn utf8ByteSequenceLength(first_byte: u8) !u3 {
// The switch is optimized much better than a "smart" approach using @clz
return switch (first_byte) {
0b0000_0000...0b0111_1111 => 1,
0b1100_0000...0b1101_1111 => 2,
0b1110_0000...0b1110_1111 => 3,
0b1111_0000...0b1111_0111 => 4,
else => error.Utf8InvalidStartByte,
};
}
/// Encodes the given codepoint into a UTF-8 byte sequence.
/// c: the codepoint.
/// out: the out buffer to write to. Must have a len >= utf8CodepointSequenceLength(c).
/// Errors: if c cannot be encoded in UTF-8.
/// Returns: the number of bytes written to out.
pub fn utf8Encode(c: u21, out: []u8) error{ Utf8CannotEncodeSurrogateHalf, CodepointTooLarge }!u3 {
return utf8EncodeImpl(c, out, .cannot_encode_surrogate_half);
}
const Surrogates = enum {
cannot_encode_surrogate_half,
can_encode_surrogate_half,
};
fn utf8EncodeImpl(c: u21, out: []u8, comptime surrogates: Surrogates) !u3 {
const length = try utf8CodepointSequenceLength(c);
assert(out.len >= length);
switch (length) {
// The pattern for each is the same
// - Increasing the initial shift by 6 each time
// - Each time after the first shorten the shifted
// value to a max of 0b111111 (63)
1 => out[0] = @as(u8, @intCast(c)), // Can just do 0 + codepoint for initial range
2 => {
out[0] = @as(u8, @intCast(0b11000000 | (c >> 6)));
out[1] = @as(u8, @intCast(0b10000000 | (c & 0b111111)));
},
3 => {
if (surrogates == .cannot_encode_surrogate_half and isSurrogateCodepoint(c)) {
return error.Utf8CannotEncodeSurrogateHalf;
}
out[0] = @as(u8, @intCast(0b11100000 | (c >> 12)));
out[1] = @as(u8, @intCast(0b10000000 | ((c >> 6) & 0b111111)));
out[2] = @as(u8, @intCast(0b10000000 | (c & 0b111111)));
},
4 => {
out[0] = @as(u8, @intCast(0b11110000 | (c >> 18)));
out[1] = @as(u8, @intCast(0b10000000 | ((c >> 12) & 0b111111)));
out[2] = @as(u8, @intCast(0b10000000 | ((c >> 6) & 0b111111)));
out[3] = @as(u8, @intCast(0b10000000 | (c & 0b111111)));
},
else => unreachable,
}
return length;
}
pub inline fn utf8EncodeComptime(comptime c: u21) [
utf8CodepointSequenceLength(c) catch |err|
@compileError(@errorName(err))
]u8 {
comptime var result: [
utf8CodepointSequenceLength(c) catch
unreachable
]u8 = undefined;
comptime assert((utf8Encode(c, &result) catch |err|
@compileError(@errorName(err))) == result.len);
return result;
}
const Utf8DecodeError = Utf8Decode2Error || Utf8Decode3Error || Utf8Decode4Error;
/// Deprecated. This function has an awkward API that is too easy to use incorrectly.
pub fn utf8Decode(bytes: []const u8) Utf8DecodeError!u21 {
return switch (bytes.len) {
1 => bytes[0],
2 => utf8Decode2(bytes[0..2].*),
3 => utf8Decode3(bytes[0..3].*),
4 => utf8Decode4(bytes[0..4].*),
else => unreachable,
};
}
const Utf8Decode2Error = error{
Utf8ExpectedContinuation,
Utf8OverlongEncoding,
};
pub fn utf8Decode2(bytes: [2]u8) Utf8Decode2Error!u21 {
assert(bytes[0] & 0b11100000 == 0b11000000);
var value: u21 = bytes[0] & 0b00011111;
if (bytes[1] & 0b11000000 != 0b10000000) return error.Utf8ExpectedContinuation;
value <<= 6;
value |= bytes[1] & 0b00111111;
if (value < 0x80) return error.Utf8OverlongEncoding;
return value;
}
const Utf8Decode3Error = Utf8Decode3AllowSurrogateHalfError || error{
Utf8EncodesSurrogateHalf,
};
pub fn utf8Decode3(bytes: [3]u8) Utf8Decode3Error!u21 {
const value = try utf8Decode3AllowSurrogateHalf(bytes);
if (0xd800 <= value and value <= 0xdfff) return error.Utf8EncodesSurrogateHalf;
return value;
}
const Utf8Decode3AllowSurrogateHalfError = error{
Utf8ExpectedContinuation,
Utf8OverlongEncoding,
};
pub fn utf8Decode3AllowSurrogateHalf(bytes: [3]u8) Utf8Decode3AllowSurrogateHalfError!u21 {
assert(bytes[0] & 0b11110000 == 0b11100000);
var value: u21 = bytes[0] & 0b00001111;
if (bytes[1] & 0b11000000 != 0b10000000) return error.Utf8ExpectedContinuation;
value <<= 6;
value |= bytes[1] & 0b00111111;
if (bytes[2] & 0b11000000 != 0b10000000) return error.Utf8ExpectedContinuation;
value <<= 6;
value |= bytes[2] & 0b00111111;
if (value < 0x800) return error.Utf8OverlongEncoding;
return value;
}
const Utf8Decode4Error = error{
Utf8ExpectedContinuation,
Utf8OverlongEncoding,
Utf8CodepointTooLarge,
};
pub fn utf8Decode4(bytes: [4]u8) Utf8Decode4Error!u21 {
assert(bytes[0] & 0b11111000 == 0b11110000);
var value: u21 = bytes[0] & 0b00000111;
if (bytes[1] & 0b11000000 != 0b10000000) return error.Utf8ExpectedContinuation;
value <<= 6;
value |= bytes[1] & 0b00111111;
if (bytes[2] & 0b11000000 != 0b10000000) return error.Utf8ExpectedContinuation;
value <<= 6;
value |= bytes[2] & 0b00111111;
if (bytes[3] & 0b11000000 != 0b10000000) return error.Utf8ExpectedContinuation;
value <<= 6;
value |= bytes[3] & 0b00111111;
if (value < 0x10000) return error.Utf8OverlongEncoding;
if (value > 0x10FFFF) return error.Utf8CodepointTooLarge;
return value;
}
/// Returns true if the given unicode codepoint can be encoded in UTF-8.
pub fn utf8ValidCodepoint(value: u21) bool {
return switch (value) {
0xD800...0xDFFF => false, // Surrogates range
0x110000...0x1FFFFF => false, // Above the maximum codepoint value
else => true,
};
}
/// Returns the length of a supplied UTF-8 string literal in terms of unicode
/// codepoints.
pub fn utf8CountCodepoints(s: []const u8) !usize {
var len: usize = 0;
const N = @sizeOf(usize);
const MASK = 0x80 * (std.math.maxInt(usize) / 0xff);
var i: usize = 0;
while (i < s.len) {
// Fast path for ASCII sequences
while (i + N <= s.len) : (i += N) {
const v = mem.readInt(usize, s[i..][0..N], native_endian);
if (v & MASK != 0) break;
len += N;
}
if (i < s.len) {
const n = try utf8ByteSequenceLength(s[i]);
if (i + n > s.len) return error.TruncatedInput;
switch (n) {
1 => {}, // ASCII, no validation needed
else => _ = try utf8Decode(s[i..][0..n]),
}
i += n;
len += 1;
}
}
return len;
}
/// Returns true if the input consists entirely of UTF-8 codepoints
pub fn utf8ValidateSlice(input: []const u8) bool {
return utf8ValidateSliceImpl(input, .cannot_encode_surrogate_half);
}
fn utf8ValidateSliceImpl(input: []const u8, comptime surrogates: Surrogates) bool {
var remaining = input;
if (std.simd.suggestVectorLength(u8)) |chunk_len| {
const Chunk = @Vector(chunk_len, u8);
// Fast path. Check for and skip ASCII characters at the start of the input.
while (remaining.len >= chunk_len) {
const chunk: Chunk = remaining[0..chunk_len].*;
const mask: Chunk = @splat(0x80);
if (@reduce(.Or, chunk & mask == mask)) {
// found a non ASCII byte
break;
}
remaining = remaining[chunk_len..];
}
}
// default lowest and highest continuation byte
const lo_cb = 0b10000000;
const hi_cb = 0b10111111;
const min_non_ascii_codepoint = 0x80;
// The first nibble is used to identify the continuation byte range to
// accept. The second nibble is the size.
const xx = 0xF1; // invalid: size 1
const as = 0xF0; // ASCII: size 1
const s1 = 0x02; // accept 0, size 2
const s2 = switch (surrogates) {
.cannot_encode_surrogate_half => 0x13, // accept 1, size 3
.can_encode_surrogate_half => 0x03, // accept 0, size 3
};
const s3 = 0x03; // accept 0, size 3
const s4 = switch (surrogates) {
.cannot_encode_surrogate_half => 0x23, // accept 2, size 3
.can_encode_surrogate_half => 0x03, // accept 0, size 3
};
const s5 = 0x34; // accept 3, size 4
const s6 = 0x04; // accept 0, size 4
const s7 = 0x44; // accept 4, size 4
// Information about the first byte in a UTF-8 sequence.
const first = comptime ([_]u8{as} ** 128) ++ ([_]u8{xx} ** 64) ++ [_]u8{
xx, xx, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1,
s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1,
s2, s3, s3, s3, s3, s3, s3, s3, s3, s3, s3, s3, s3, s4, s3, s3,
s5, s6, s6, s6, s7, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx,
};
const n = remaining.len;
var i: usize = 0;
while (i < n) {
const first_byte = remaining[i];
if (first_byte < min_non_ascii_codepoint) {
i += 1;
continue;
}
const info = first[first_byte];
if (info == xx) {
return false; // Illegal starter byte.
}
const size = info & 7;
if (i + size > n) {
return false; // Short or invalid.
}
// Figure out the acceptable low and high continuation bytes, starting
// with our defaults.
var accept_lo: u8 = lo_cb;
var accept_hi: u8 = hi_cb;
switch (info >> 4) {
0 => {},
1 => accept_lo = 0xA0,
2 => accept_hi = 0x9F,
3 => accept_lo = 0x90,
4 => accept_hi = 0x8F,
else => unreachable,
}
const c1 = remaining[i + 1];
if (c1 < accept_lo or accept_hi < c1) {
return false;
}
switch (size) {
2 => i += 2,
3 => {
const c2 = remaining[i + 2];
if (c2 < lo_cb or hi_cb < c2) {
return false;
}
i += 3;
},
4 => {
const c2 = remaining[i + 2];
if (c2 < lo_cb or hi_cb < c2) {
return false;
}
const c3 = remaining[i + 3];
if (c3 < lo_cb or hi_cb < c3) {
return false;
}
i += 4;
},
else => unreachable,
}
}
return true;
}
/// Utf8View iterates the code points of a utf-8 encoded string.
///
/// ```
/// var utf8 = (try std.unicode.Utf8View.init("hi there")).iterator();
/// while (utf8.nextCodepointSlice()) |codepoint| {
/// std.debug.print("got codepoint {s}\n", .{codepoint});
/// }
/// ```
pub const Utf8View = struct {
bytes: []const u8,
pub fn init(s: []const u8) !Utf8View {
if (!utf8ValidateSlice(s)) {
return error.InvalidUtf8;
}
return initUnchecked(s);
}
pub fn initUnchecked(s: []const u8) Utf8View {
return Utf8View{ .bytes = s };
}
pub inline fn initComptime(comptime s: []const u8) Utf8View {
return comptime if (init(s)) |r| r else |err| switch (err) {
error.InvalidUtf8 => {
@compileError("invalid utf8");
},
};
}
pub fn iterator(s: Utf8View) Utf8Iterator {
return Utf8Iterator{
.bytes = s.bytes,
.i = 0,
};
}
};
pub const Utf8Iterator = struct {
bytes: []const u8,
i: usize,
pub fn nextCodepointSlice(it: *Utf8Iterator) ?[]const u8 {
if (it.i >= it.bytes.len) {
return null;
}
const cp_len = utf8ByteSequenceLength(it.bytes[it.i]) catch unreachable;
it.i += cp_len;
return it.bytes[it.i - cp_len .. it.i];
}
pub fn nextCodepoint(it: *Utf8Iterator) ?u21 {
const slice = it.nextCodepointSlice() orelse return null;
return utf8Decode(slice) catch unreachable;
}
/// Look ahead at the next n codepoints without advancing the iterator.
/// If fewer than n codepoints are available, then return the remainder of the string.
pub fn peek(it: *Utf8Iterator, n: usize) []const u8 {
const original_i = it.i;
defer it.i = original_i;
var end_ix = original_i;
var found: usize = 0;
while (found < n) : (found += 1) {
const next_codepoint = it.nextCodepointSlice() orelse return it.bytes[original_i..];
end_ix += next_codepoint.len;
}
return it.bytes[original_i..end_ix];
}
};
pub fn utf16IsHighSurrogate(c: u16) bool {
return c & ~@as(u16, 0x03ff) == 0xd800;
}
pub fn utf16IsLowSurrogate(c: u16) bool {
return c & ~@as(u16, 0x03ff) == 0xdc00;
}
/// Returns how many code units the UTF-16 representation would require
/// for the given codepoint.
pub fn utf16CodepointSequenceLength(c: u21) !u2 {
if (c <= 0xFFFF) return 1;
if (c <= 0x10FFFF) return 2;
return error.CodepointTooLarge;
}
test utf16CodepointSequenceLength {
try testing.expectEqual(@as(u2, 1), try utf16CodepointSequenceLength('a'));
try testing.expectEqual(@as(u2, 1), try utf16CodepointSequenceLength(0xFFFF));
try testing.expectEqual(@as(u2, 2), try utf16CodepointSequenceLength(0x10000));
try testing.expectEqual(@as(u2, 2), try utf16CodepointSequenceLength(0x10FFFF));
try testing.expectError(error.CodepointTooLarge, utf16CodepointSequenceLength(0x110000));
}
/// Given the first code unit of a UTF-16 codepoint, returns a number 1-2
/// indicating the total length of the codepoint in UTF-16 code units.
/// If this code unit does not match the form of a UTF-16 start code unit, returns Utf16InvalidStartCodeUnit.
pub fn utf16CodeUnitSequenceLength(first_code_unit: u16) !u2 {
if (utf16IsHighSurrogate(first_code_unit)) return 2;
if (utf16IsLowSurrogate(first_code_unit)) return error.Utf16InvalidStartCodeUnit;
return 1;
}
test utf16CodeUnitSequenceLength {
try testing.expectEqual(@as(u2, 1), try utf16CodeUnitSequenceLength('a'));
try testing.expectEqual(@as(u2, 1), try utf16CodeUnitSequenceLength(0xFFFF));
try testing.expectEqual(@as(u2, 2), try utf16CodeUnitSequenceLength(0xDBFF));
try testing.expectError(error.Utf16InvalidStartCodeUnit, utf16CodeUnitSequenceLength(0xDFFF));
}
/// Decodes the codepoint encoded in the given pair of UTF-16 code units.
/// Asserts that `surrogate_pair.len >= 2` and that the first code unit is a high surrogate.
/// If the second code unit is not a low surrogate, error.ExpectedSecondSurrogateHalf is returned.
pub fn utf16DecodeSurrogatePair(surrogate_pair: []const u16) !u21 {
assert(surrogate_pair.len >= 2);
assert(utf16IsHighSurrogate(surrogate_pair[0]));
const high_half: u21 = surrogate_pair[0];
const low_half = surrogate_pair[1];
if (!utf16IsLowSurrogate(low_half)) return error.ExpectedSecondSurrogateHalf;
return 0x10000 + ((high_half & 0x03ff) << 10) | (low_half & 0x03ff);
}
pub const Utf16LeIterator = struct {
bytes: []const u8,
i: usize,
pub fn init(s: []const u16) Utf16LeIterator {
return Utf16LeIterator{
.bytes = mem.sliceAsBytes(s),
.i = 0,
};
}
pub const NextCodepointError = error{ DanglingSurrogateHalf, ExpectedSecondSurrogateHalf, UnexpectedSecondSurrogateHalf };
pub fn nextCodepoint(it: *Utf16LeIterator) NextCodepointError!?u21 {
assert(it.i <= it.bytes.len);
if (it.i == it.bytes.len) return null;
var code_units: [2]u16 = undefined;
code_units[0] = mem.readInt(u16, it.bytes[it.i..][0..2], .little);
it.i += 2;
if (utf16IsHighSurrogate(code_units[0])) {
// surrogate pair
if (it.i >= it.bytes.len) return error.DanglingSurrogateHalf;
code_units[1] = mem.readInt(u16, it.bytes[it.i..][0..2], .little);
const codepoint = try utf16DecodeSurrogatePair(&code_units);
it.i += 2;
return codepoint;
} else if (utf16IsLowSurrogate(code_units[0])) {
return error.UnexpectedSecondSurrogateHalf;
} else {
return code_units[0];
}
}
};
/// Returns the length of a supplied UTF-16 string literal in terms of unicode
/// codepoints.
pub fn utf16CountCodepoints(utf16le: []const u16) !usize {
var len: usize = 0;
var it = Utf16LeIterator.init(utf16le);
while (try it.nextCodepoint()) |_| len += 1;
return len;
}
fn testUtf16CountCodepoints() !void {
try testing.expectEqual(
@as(usize, 1),
try utf16CountCodepoints(utf8ToUtf16LeStringLiteral("a")),
);
try testing.expectEqual(
@as(usize, 10),
try utf16CountCodepoints(utf8ToUtf16LeStringLiteral("abcdefghij")),
);
try testing.expectEqual(
@as(usize, 10),
try utf16CountCodepoints(utf8ToUtf16LeStringLiteral("äåéëþüúíóö")),
);
try testing.expectEqual(
@as(usize, 5),
try utf16CountCodepoints(utf8ToUtf16LeStringLiteral("こんにちは")),
);
}
test "utf16 count codepoints" {
try testUtf16CountCodepoints();
try comptime testUtf16CountCodepoints();
}
test "utf8 encode" {
try comptime testUtf8Encode();
try testUtf8Encode();
}
fn testUtf8Encode() !void {
// A few taken from wikipedia a few taken elsewhere
var array: [4]u8 = undefined;
try testing.expect((try utf8Encode(try utf8Decode(""), array[0..])) == 3);
try testing.expect(array[0] == 0b11100010);
try testing.expect(array[1] == 0b10000010);
try testing.expect(array[2] == 0b10101100);
try testing.expect((try utf8Encode(try utf8Decode("$"), array[0..])) == 1);
try testing.expect(array[0] == 0b00100100);
try testing.expect((try utf8Encode(try utf8Decode("¢"), array[0..])) == 2);
try testing.expect(array[0] == 0b11000010);
try testing.expect(array[1] == 0b10100010);
try testing.expect((try utf8Encode(try utf8Decode("𐍈"), array[0..])) == 4);
try testing.expect(array[0] == 0b11110000);
try testing.expect(array[1] == 0b10010000);
try testing.expect(array[2] == 0b10001101);
try testing.expect(array[3] == 0b10001000);
}
test "utf8 encode comptime" {
try testing.expectEqualSlices(u8, "", &utf8EncodeComptime('€'));
try testing.expectEqualSlices(u8, "$", &utf8EncodeComptime('$'));
try testing.expectEqualSlices(u8, "¢", &utf8EncodeComptime('¢'));
try testing.expectEqualSlices(u8, "𐍈", &utf8EncodeComptime('𐍈'));
}
test "utf8 encode error" {
try comptime testUtf8EncodeError();
try testUtf8EncodeError();
}
fn testUtf8EncodeError() !void {
var array: [4]u8 = undefined;
try testErrorEncode(0xd800, array[0..], error.Utf8CannotEncodeSurrogateHalf);
try testErrorEncode(0xdfff, array[0..], error.Utf8CannotEncodeSurrogateHalf);
try testErrorEncode(0x110000, array[0..], error.CodepointTooLarge);
try testErrorEncode(0x1fffff, array[0..], error.CodepointTooLarge);
}
fn testErrorEncode(codePoint: u21, array: []u8, expectedErr: anyerror) !void {
try testing.expectError(expectedErr, utf8Encode(codePoint, array));
}
test "utf8 iterator on ascii" {
try comptime testUtf8IteratorOnAscii();
try testUtf8IteratorOnAscii();
}
fn testUtf8IteratorOnAscii() !void {
const s = Utf8View.initComptime("abc");
var it1 = s.iterator();
try testing.expect(mem.eql(u8, "a", it1.nextCodepointSlice().?));
try testing.expect(mem.eql(u8, "b", it1.nextCodepointSlice().?));
try testing.expect(mem.eql(u8, "c", it1.nextCodepointSlice().?));
try testing.expect(it1.nextCodepointSlice() == null);
var it2 = s.iterator();
try testing.expect(it2.nextCodepoint().? == 'a');
try testing.expect(it2.nextCodepoint().? == 'b');
try testing.expect(it2.nextCodepoint().? == 'c');
try testing.expect(it2.nextCodepoint() == null);
}
test "utf8 view bad" {
try comptime testUtf8ViewBad();
try testUtf8ViewBad();
}
fn testUtf8ViewBad() !void {
// Compile-time error.
// const s3 = Utf8View.initComptime("\xfe\xf2");
try testing.expectError(error.InvalidUtf8, Utf8View.init("hel\xadlo"));
}
test "utf8 view ok" {
try comptime testUtf8ViewOk();
try testUtf8ViewOk();
}
fn testUtf8ViewOk() !void {
const s = Utf8View.initComptime("東京市");
var it1 = s.iterator();
try testing.expect(mem.eql(u8, "", it1.nextCodepointSlice().?));
try testing.expect(mem.eql(u8, "", it1.nextCodepointSlice().?));
try testing.expect(mem.eql(u8, "", it1.nextCodepointSlice().?));
try testing.expect(it1.nextCodepointSlice() == null);
var it2 = s.iterator();
try testing.expect(it2.nextCodepoint().? == 0x6771);
try testing.expect(it2.nextCodepoint().? == 0x4eac);
try testing.expect(it2.nextCodepoint().? == 0x5e02);
try testing.expect(it2.nextCodepoint() == null);
}
test "validate slice" {
try comptime testValidateSlice();
try testValidateSlice();
// We skip a variable (based on recommended vector size) chunks of
// ASCII characters. Let's make sure we're chunking correctly.
const str = [_]u8{'a'} ** 550 ++ "\xc0";
for (0..str.len - 3) |i| {
try testing.expect(!utf8ValidateSlice(str[i..]));
}
}
fn testValidateSlice() !void {
try testing.expect(utf8ValidateSlice("abc"));
try testing.expect(utf8ValidateSlice("abc\xdf\xbf"));
try testing.expect(utf8ValidateSlice(""));
try testing.expect(utf8ValidateSlice("a"));
try testing.expect(utf8ValidateSlice("abc"));
try testing.expect(utf8ValidateSlice("Ж"));
try testing.expect(utf8ValidateSlice("ЖЖ"));
try testing.expect(utf8ValidateSlice("брэд-ЛГТМ"));
try testing.expect(utf8ValidateSlice("☺☻☹"));
try testing.expect(utf8ValidateSlice("a\u{fffdb}"));
try testing.expect(utf8ValidateSlice("\xf4\x8f\xbf\xbf"));
try testing.expect(utf8ValidateSlice("abc\xdf\xbf"));
try testing.expect(!utf8ValidateSlice("abc\xc0"));
try testing.expect(!utf8ValidateSlice("abc\xc0abc"));
try testing.expect(!utf8ValidateSlice("aa\xe2"));
try testing.expect(!utf8ValidateSlice("\x42\xfa"));
try testing.expect(!utf8ValidateSlice("\x42\xfa\x43"));
try testing.expect(!utf8ValidateSlice("abc\xc0"));
try testing.expect(!utf8ValidateSlice("abc\xc0abc"));
try testing.expect(!utf8ValidateSlice("\xf4\x90\x80\x80"));
try testing.expect(!utf8ValidateSlice("\xf7\xbf\xbf\xbf"));
try testing.expect(!utf8ValidateSlice("\xfb\xbf\xbf\xbf\xbf"));
try testing.expect(!utf8ValidateSlice("\xc0\x80"));
try testing.expect(!utf8ValidateSlice("\xed\xa0\x80"));
try testing.expect(!utf8ValidateSlice("\xed\xbf\xbf"));
}
test "valid utf8" {
try comptime testValidUtf8();
try testValidUtf8();
}
fn testValidUtf8() !void {
try testValid("\x00", 0x0);
try testValid("\x20", 0x20);
try testValid("\x7f", 0x7f);
try testValid("\xc2\x80", 0x80);
try testValid("\xdf\xbf", 0x7ff);
try testValid("\xe0\xa0\x80", 0x800);
try testValid("\xe1\x80\x80", 0x1000);
try testValid("\xef\xbf\xbf", 0xffff);
try testValid("\xf0\x90\x80\x80", 0x10000);
try testValid("\xf1\x80\x80\x80", 0x40000);
try testValid("\xf3\xbf\xbf\xbf", 0xfffff);
try testValid("\xf4\x8f\xbf\xbf", 0x10ffff);
}
test "invalid utf8 continuation bytes" {
try comptime testInvalidUtf8ContinuationBytes();
try testInvalidUtf8ContinuationBytes();
}
fn testInvalidUtf8ContinuationBytes() !void {
// unexpected continuation
try testError("\x80", error.Utf8InvalidStartByte);
try testError("\xbf", error.Utf8InvalidStartByte);
// too many leading 1's
try testError("\xf8", error.Utf8InvalidStartByte);
try testError("\xff", error.Utf8InvalidStartByte);
// expected continuation for 2 byte sequences
try testError("\xc2", error.UnexpectedEof);
try testError("\xc2\x00", error.Utf8ExpectedContinuation);
try testError("\xc2\xc0", error.Utf8ExpectedContinuation);
// expected continuation for 3 byte sequences
try testError("\xe0", error.UnexpectedEof);
try testError("\xe0\x00", error.UnexpectedEof);
try testError("\xe0\xc0", error.UnexpectedEof);
try testError("\xe0\xa0", error.UnexpectedEof);
try testError("\xe0\xa0\x00", error.Utf8ExpectedContinuation);
try testError("\xe0\xa0\xc0", error.Utf8ExpectedContinuation);
// expected continuation for 4 byte sequences
try testError("\xf0", error.UnexpectedEof);
try testError("\xf0\x00", error.UnexpectedEof);
try testError("\xf0\xc0", error.UnexpectedEof);
try testError("\xf0\x90\x00", error.UnexpectedEof);
try testError("\xf0\x90\xc0", error.UnexpectedEof);
try testError("\xf0\x90\x80\x00", error.Utf8ExpectedContinuation);
try testError("\xf0\x90\x80\xc0", error.Utf8ExpectedContinuation);
}
test "overlong utf8 codepoint" {
try comptime testOverlongUtf8Codepoint();
try testOverlongUtf8Codepoint();
}
fn testOverlongUtf8Codepoint() !void {
try testError("\xc0\x80", error.Utf8OverlongEncoding);
try testError("\xc1\xbf", error.Utf8OverlongEncoding);
try testError("\xe0\x80\x80", error.Utf8OverlongEncoding);
try testError("\xe0\x9f\xbf", error.Utf8OverlongEncoding);
try testError("\xf0\x80\x80\x80", error.Utf8OverlongEncoding);
try testError("\xf0\x8f\xbf\xbf", error.Utf8OverlongEncoding);
}
test "misc invalid utf8" {
try comptime testMiscInvalidUtf8();
try testMiscInvalidUtf8();
}
fn testMiscInvalidUtf8() !void {
// codepoint out of bounds
try testError("\xf4\x90\x80\x80", error.Utf8CodepointTooLarge);
try testError("\xf7\xbf\xbf\xbf", error.Utf8CodepointTooLarge);
// surrogate halves
try testValid("\xed\x9f\xbf", 0xd7ff);
try testError("\xed\xa0\x80", error.Utf8EncodesSurrogateHalf);
try testError("\xed\xbf\xbf", error.Utf8EncodesSurrogateHalf);
try testValid("\xee\x80\x80", 0xe000);
}
test "utf8 iterator peeking" {
try comptime testUtf8Peeking();
try testUtf8Peeking();
}
fn testUtf8Peeking() !void {
const s = Utf8View.initComptime("noël");
var it = s.iterator();
try testing.expect(mem.eql(u8, "n", it.nextCodepointSlice().?));
try testing.expect(mem.eql(u8, "o", it.peek(1)));
try testing.expect(mem.eql(u8, "", it.peek(2)));
try testing.expect(mem.eql(u8, "oël", it.peek(3)));
try testing.expect(mem.eql(u8, "oël", it.peek(4)));
try testing.expect(mem.eql(u8, "oël", it.peek(10)));
try testing.expect(mem.eql(u8, "o", it.nextCodepointSlice().?));
try testing.expect(mem.eql(u8, "ë", it.nextCodepointSlice().?));
try testing.expect(mem.eql(u8, "l", it.nextCodepointSlice().?));
try testing.expect(it.nextCodepointSlice() == null);
try testing.expect(mem.eql(u8, &[_]u8{}, it.peek(1)));
}
fn testError(bytes: []const u8, expected_err: anyerror) !void {
try testing.expectError(expected_err, testDecode(bytes));
}
fn testValid(bytes: []const u8, expected_codepoint: u21) !void {
try testing.expect((testDecode(bytes) catch unreachable) == expected_codepoint);
}
fn testDecode(bytes: []const u8) !u21 {
const length = try utf8ByteSequenceLength(bytes[0]);
if (bytes.len < length) return error.UnexpectedEof;
try testing.expect(bytes.len == length);
return utf8Decode(bytes);
}
/// Print the given `utf8` string, encoded as UTF-8 bytes.
/// Ill-formed UTF-8 byte sequences are replaced by the replacement character (U+FFFD)
/// according to "U+FFFD Substitution of Maximal Subparts" from Chapter 3 of
/// the Unicode standard, and as specified by https://encoding.spec.whatwg.org/#utf-8-decoder
fn formatUtf8(
utf8: []const u8,
comptime fmt: []const u8,
options: std.fmt.FormatOptions,
writer: anytype,
) !void {
_ = fmt;
_ = options;
var buf: [300]u8 = undefined; // just an arbitrary size
var u8len: usize = 0;
// This implementation is based on this specification:
// https://encoding.spec.whatwg.org/#utf-8-decoder
var codepoint: u21 = 0;
var cont_bytes_seen: u3 = 0;
var cont_bytes_needed: u3 = 0;
var lower_boundary: u8 = 0x80;
var upper_boundary: u8 = 0xBF;
var i: usize = 0;
while (i < utf8.len) {
const byte = utf8[i];
if (cont_bytes_needed == 0) {
switch (byte) {
0x00...0x7F => {
buf[u8len] = byte;
u8len += 1;
},
0xC2...0xDF => {
cont_bytes_needed = 1;
codepoint = byte & 0b00011111;
},
0xE0...0xEF => {
if (byte == 0xE0) lower_boundary = 0xA0;
if (byte == 0xED) upper_boundary = 0x9F;
cont_bytes_needed = 2;
codepoint = byte & 0b00001111;
},
0xF0...0xF4 => {
if (byte == 0xF0) lower_boundary = 0x90;
if (byte == 0xF4) upper_boundary = 0x8F;
cont_bytes_needed = 3;
codepoint = byte & 0b00000111;
},
else => {
u8len += utf8Encode(replacement_character, buf[u8len..]) catch unreachable;
},
}
// consume the byte
i += 1;
} else if (byte < lower_boundary or byte > upper_boundary) {
codepoint = 0;
cont_bytes_needed = 0;
cont_bytes_seen = 0;
lower_boundary = 0x80;
upper_boundary = 0xBF;
u8len += utf8Encode(replacement_character, buf[u8len..]) catch unreachable;
// do not consume the current byte, it should now be treated as a possible start byte
} else {
lower_boundary = 0x80;
upper_boundary = 0xBF;
codepoint <<= 6;
codepoint |= byte & 0b00111111;
cont_bytes_seen += 1;
// consume the byte
i += 1;
if (cont_bytes_seen == cont_bytes_needed) {
const codepoint_len = cont_bytes_seen + 1;
const codepoint_start_i = i - codepoint_len;
@memcpy(buf[u8len..][0..codepoint_len], utf8[codepoint_start_i..][0..codepoint_len]);
u8len += codepoint_len;
codepoint = 0;
cont_bytes_needed = 0;
cont_bytes_seen = 0;
}
}
// make sure there's always enough room for another maximum length UTF-8 codepoint
if (u8len + 4 > buf.len) {
try writer.writeAll(buf[0..u8len]);
u8len = 0;
}
}
if (cont_bytes_needed != 0) {
// we know there's enough room because we always flush
// if there's less than 4 bytes remaining in the buffer.
u8len += utf8Encode(replacement_character, buf[u8len..]) catch unreachable;
}
try writer.writeAll(buf[0..u8len]);
}
/// Return a Formatter for a (potentially ill-formed) UTF-8 string.
/// Ill-formed UTF-8 byte sequences are replaced by the replacement character (U+FFFD)
/// according to "U+FFFD Substitution of Maximal Subparts" from Chapter 3 of
/// the Unicode standard, and as specified by https://encoding.spec.whatwg.org/#utf-8-decoder
pub fn fmtUtf8(utf8: []const u8) std.fmt.Formatter(formatUtf8) {
return .{ .data = utf8 };
}
test fmtUtf8 {
const expectFmt = testing.expectFmt;
try expectFmt("", "{}", .{fmtUtf8("")});
try expectFmt("foo", "{}", .{fmtUtf8("foo")});
try expectFmt("𐐷", "{}", .{fmtUtf8("𐐷")});
// Table 3-8. U+FFFD for Non-Shortest Form Sequences
try expectFmt("<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>A", "{}", .{fmtUtf8("\xC0\xAF\xE0\x80\xBF\xF0\x81\x82A")});
// Table 3-9. U+FFFD for Ill-Formed Sequences for Surrogates
try expectFmt("<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>A", "{}", .{fmtUtf8("\xED\xA0\x80\xED\xBF\xBF\xED\xAFA")});
// Table 3-10. U+FFFD for Other Ill-Formed Sequences
try expectFmt("<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>A<EFBFBD><EFBFBD>B", "{}", .{fmtUtf8("\xF4\x91\x92\x93\xFFA\x80\xBFB")});
// Table 3-11. U+FFFD for Truncated Sequences
try expectFmt("<EFBFBD><EFBFBD><EFBFBD><EFBFBD>A", "{}", .{fmtUtf8("\xE1\x80\xE2\xF0\x91\x92\xF1\xBFA")});
}
fn utf16LeToUtf8ArrayListImpl(
result: *std.ArrayList(u8),
utf16le: []const u16,
comptime surrogates: Surrogates,
) (switch (surrogates) {
.cannot_encode_surrogate_half => Utf16LeToUtf8AllocError,
.can_encode_surrogate_half => mem.Allocator.Error,
})!void {
assert(result.unusedCapacitySlice().len >= utf16le.len);
var remaining = utf16le;
vectorized: {
const chunk_len = std.simd.suggestVectorLength(u16) orelse break :vectorized;
const Chunk = @Vector(chunk_len, u16);
// Fast path. Check for and encode ASCII characters at the start of the input.
while (remaining.len >= chunk_len) {
const chunk: Chunk = remaining[0..chunk_len].*;
const mask: Chunk = @splat(mem.nativeToLittle(u16, 0x7F));
if (@reduce(.Or, chunk | mask != mask)) {
// found a non ASCII code unit
break;
}
const ascii_chunk: @Vector(chunk_len, u8) = @truncate(mem.nativeToLittle(Chunk, chunk));
// We allocated enough space to encode every UTF-16 code unit
// as ASCII, so if the entire string is ASCII then we are
// guaranteed to have enough space allocated
result.addManyAsArrayAssumeCapacity(chunk_len).* = ascii_chunk;
remaining = remaining[chunk_len..];
}
}
switch (surrogates) {
.cannot_encode_surrogate_half => {
var it = Utf16LeIterator.init(remaining);
while (try it.nextCodepoint()) |codepoint| {
const utf8_len = utf8CodepointSequenceLength(codepoint) catch unreachable;
assert((utf8Encode(codepoint, try result.addManyAsSlice(utf8_len)) catch unreachable) == utf8_len);
}
},
.can_encode_surrogate_half => {
var it = Wtf16LeIterator.init(remaining);
while (it.nextCodepoint()) |codepoint| {
const utf8_len = utf8CodepointSequenceLength(codepoint) catch unreachable;
assert((wtf8Encode(codepoint, try result.addManyAsSlice(utf8_len)) catch unreachable) == utf8_len);
}
},
}
}
pub const Utf16LeToUtf8AllocError = mem.Allocator.Error || Utf16LeToUtf8Error;
pub fn utf16LeToUtf8ArrayList(result: *std.ArrayList(u8), utf16le: []const u16) Utf16LeToUtf8AllocError!void {
try result.ensureUnusedCapacity(utf16le.len);
return utf16LeToUtf8ArrayListImpl(result, utf16le, .cannot_encode_surrogate_half);
}
pub const utf16leToUtf8Alloc = @compileError("deprecated; renamed to utf16LeToUtf8Alloc");
/// Caller must free returned memory.
pub fn utf16LeToUtf8Alloc(allocator: mem.Allocator, utf16le: []const u16) Utf16LeToUtf8AllocError![]u8 {
// optimistically guess that it will all be ascii.
var result = try std.ArrayList(u8).initCapacity(allocator, utf16le.len);
errdefer result.deinit();
try utf16LeToUtf8ArrayListImpl(&result, utf16le, .cannot_encode_surrogate_half);
return result.toOwnedSlice();
}
pub const utf16leToUtf8AllocZ = @compileError("deprecated; renamed to utf16LeToUtf8AllocZ");
/// Caller must free returned memory.
pub fn utf16LeToUtf8AllocZ(allocator: mem.Allocator, utf16le: []const u16) Utf16LeToUtf8AllocError![:0]u8 {
// optimistically guess that it will all be ascii (and allocate space for the null terminator)
var result = try std.ArrayList(u8).initCapacity(allocator, utf16le.len + 1);
errdefer result.deinit();
try utf16LeToUtf8ArrayListImpl(&result, utf16le, .cannot_encode_surrogate_half);
return result.toOwnedSliceSentinel(0);
}
pub const Utf16LeToUtf8Error = Utf16LeIterator.NextCodepointError;
/// Asserts that the output buffer is big enough.
/// Returns end byte index into utf8.
fn utf16LeToUtf8Impl(utf8: []u8, utf16le: []const u16, comptime surrogates: Surrogates) (switch (surrogates) {
.cannot_encode_surrogate_half => Utf16LeToUtf8Error,
.can_encode_surrogate_half => error{},
})!usize {
var dest_index: usize = 0;
var remaining = utf16le;
vectorized: {
const chunk_len = std.simd.suggestVectorLength(u16) orelse break :vectorized;
const Chunk = @Vector(chunk_len, u16);
// Fast path. Check for and encode ASCII characters at the start of the input.
while (remaining.len >= chunk_len) {
const chunk: Chunk = remaining[0..chunk_len].*;
const mask: Chunk = @splat(mem.nativeToLittle(u16, 0x7F));
if (@reduce(.Or, chunk | mask != mask)) {
// found a non ASCII code unit
break;
}
const ascii_chunk: @Vector(chunk_len, u8) = @truncate(mem.nativeToLittle(Chunk, chunk));
utf8[dest_index..][0..chunk_len].* = ascii_chunk;
dest_index += chunk_len;
remaining = remaining[chunk_len..];
}
}
switch (surrogates) {
.cannot_encode_surrogate_half => {
var it = Utf16LeIterator.init(remaining);
while (try it.nextCodepoint()) |codepoint| {
dest_index += utf8Encode(codepoint, utf8[dest_index..]) catch |err| switch (err) {
// The maximum possible codepoint encoded by UTF-16 is U+10FFFF,
// which is within the valid codepoint range.
error.CodepointTooLarge => unreachable,
// We know the codepoint was valid in UTF-16, meaning it is not
// an unpaired surrogate codepoint.
error.Utf8CannotEncodeSurrogateHalf => unreachable,
};
}
},
.can_encode_surrogate_half => {
var it = Wtf16LeIterator.init(remaining);
while (it.nextCodepoint()) |codepoint| {
dest_index += wtf8Encode(codepoint, utf8[dest_index..]) catch |err| switch (err) {
// The maximum possible codepoint encoded by UTF-16 is U+10FFFF,
// which is within the valid codepoint range.
error.CodepointTooLarge => unreachable,
};
}
},
}
return dest_index;
}
pub const utf16leToUtf8 = @compileError("deprecated; renamed to utf16LeToUtf8");
pub fn utf16LeToUtf8(utf8: []u8, utf16le: []const u16) Utf16LeToUtf8Error!usize {
return utf16LeToUtf8Impl(utf8, utf16le, .cannot_encode_surrogate_half);
}
test utf16LeToUtf8 {
var utf16le: [2]u16 = undefined;
const utf16le_as_bytes = mem.sliceAsBytes(utf16le[0..]);
{
mem.writeInt(u16, utf16le_as_bytes[0..2], 'A', .little);
mem.writeInt(u16, utf16le_as_bytes[2..4], 'a', .little);
const utf8 = try utf16LeToUtf8Alloc(testing.allocator, &utf16le);
defer testing.allocator.free(utf8);
try testing.expect(mem.eql(u8, utf8, "Aa"));
}
{
mem.writeInt(u16, utf16le_as_bytes[0..2], 0x80, .little);
mem.writeInt(u16, utf16le_as_bytes[2..4], 0xffff, .little);
const utf8 = try utf16LeToUtf8Alloc(testing.allocator, &utf16le);
defer testing.allocator.free(utf8);
try testing.expect(mem.eql(u8, utf8, "\xc2\x80" ++ "\xef\xbf\xbf"));
}
{
// the values just outside the surrogate half range
mem.writeInt(u16, utf16le_as_bytes[0..2], 0xd7ff, .little);
mem.writeInt(u16, utf16le_as_bytes[2..4], 0xe000, .little);
const utf8 = try utf16LeToUtf8Alloc(testing.allocator, &utf16le);
defer testing.allocator.free(utf8);
try testing.expect(mem.eql(u8, utf8, "\xed\x9f\xbf" ++ "\xee\x80\x80"));
}
{
// smallest surrogate pair
mem.writeInt(u16, utf16le_as_bytes[0..2], 0xd800, .little);
mem.writeInt(u16, utf16le_as_bytes[2..4], 0xdc00, .little);
const utf8 = try utf16LeToUtf8Alloc(testing.allocator, &utf16le);
defer testing.allocator.free(utf8);
try testing.expect(mem.eql(u8, utf8, "\xf0\x90\x80\x80"));
}
{
// largest surrogate pair
mem.writeInt(u16, utf16le_as_bytes[0..2], 0xdbff, .little);
mem.writeInt(u16, utf16le_as_bytes[2..4], 0xdfff, .little);
const utf8 = try utf16LeToUtf8Alloc(testing.allocator, &utf16le);
defer testing.allocator.free(utf8);
try testing.expect(mem.eql(u8, utf8, "\xf4\x8f\xbf\xbf"));
}
{
mem.writeInt(u16, utf16le_as_bytes[0..2], 0xdbff, .little);
mem.writeInt(u16, utf16le_as_bytes[2..4], 0xdc00, .little);
const utf8 = try utf16LeToUtf8Alloc(testing.allocator, &utf16le);
defer testing.allocator.free(utf8);
try testing.expect(mem.eql(u8, utf8, "\xf4\x8f\xb0\x80"));
}
{
mem.writeInt(u16, utf16le_as_bytes[0..2], 0xdcdc, .little);
mem.writeInt(u16, utf16le_as_bytes[2..4], 0xdcdc, .little);
const result = utf16LeToUtf8Alloc(testing.allocator, &utf16le);
try testing.expectError(error.UnexpectedSecondSurrogateHalf, result);
}
}
fn utf8ToUtf16LeArrayListImpl(result: *std.ArrayList(u16), utf8: []const u8, comptime surrogates: Surrogates) !void {
assert(result.unusedCapacitySlice().len >= utf8.len);
var remaining = utf8;
vectorized: {
const chunk_len = std.simd.suggestVectorLength(u16) orelse break :vectorized;
const Chunk = @Vector(chunk_len, u8);
// Fast path. Check for and encode ASCII characters at the start of the input.
while (remaining.len >= chunk_len) {
const chunk: Chunk = remaining[0..chunk_len].*;
const mask: Chunk = @splat(0x80);
if (@reduce(.Or, chunk & mask == mask)) {
// found a non ASCII code unit
break;
}
const utf16_chunk = mem.nativeToLittle(@Vector(chunk_len, u16), chunk);
result.addManyAsArrayAssumeCapacity(chunk_len).* = utf16_chunk;
remaining = remaining[chunk_len..];
}
}
const view = switch (surrogates) {
.cannot_encode_surrogate_half => try Utf8View.init(remaining),
.can_encode_surrogate_half => try Wtf8View.init(remaining),
};
var it = view.iterator();
while (it.nextCodepoint()) |codepoint| {
if (codepoint < 0x10000) {
try result.append(mem.nativeToLittle(u16, @intCast(codepoint)));
} else {
const high = @as(u16, @intCast((codepoint - 0x10000) >> 10)) + 0xD800;
const low = @as(u16, @intCast(codepoint & 0x3FF)) + 0xDC00;
try result.appendSlice(&.{ mem.nativeToLittle(u16, high), mem.nativeToLittle(u16, low) });
}
}
}
pub fn utf8ToUtf16LeArrayList(result: *std.ArrayList(u16), utf8: []const u8) error{ InvalidUtf8, OutOfMemory }!void {
try result.ensureUnusedCapacity(utf8.len);
return utf8ToUtf16LeArrayListImpl(result, utf8, .cannot_encode_surrogate_half);
}
pub fn utf8ToUtf16LeAlloc(allocator: mem.Allocator, utf8: []const u8) error{ InvalidUtf8, OutOfMemory }![]u16 {
// optimistically guess that it will not require surrogate pairs
var result = try std.ArrayList(u16).initCapacity(allocator, utf8.len);
errdefer result.deinit();
try utf8ToUtf16LeArrayListImpl(&result, utf8, .cannot_encode_surrogate_half);
return result.toOwnedSlice();
}
pub const utf8ToUtf16LeWithNull = @compileError("deprecated; renamed to utf8ToUtf16LeAllocZ");
pub fn utf8ToUtf16LeAllocZ(allocator: mem.Allocator, utf8: []const u8) error{ InvalidUtf8, OutOfMemory }![:0]u16 {
// optimistically guess that it will not require surrogate pairs
var result = try std.ArrayList(u16).initCapacity(allocator, utf8.len + 1);
errdefer result.deinit();
try utf8ToUtf16LeArrayListImpl(&result, utf8, .cannot_encode_surrogate_half);
return result.toOwnedSliceSentinel(0);
}
/// Returns index of next character. If exact fit, returned index equals output slice length.
/// Assumes there is enough space for the output.
pub fn utf8ToUtf16Le(utf16le: []u16, utf8: []const u8) error{InvalidUtf8}!usize {
return utf8ToUtf16LeImpl(utf16le, utf8, .cannot_encode_surrogate_half);
}
pub fn utf8ToUtf16LeImpl(utf16le: []u16, utf8: []const u8, comptime surrogates: Surrogates) !usize {
var dest_index: usize = 0;
var remaining = utf8;
vectorized: {
const chunk_len = std.simd.suggestVectorLength(u16) orelse break :vectorized;
const Chunk = @Vector(chunk_len, u8);
// Fast path. Check for and encode ASCII characters at the start of the input.
while (remaining.len >= chunk_len) {
const chunk: Chunk = remaining[0..chunk_len].*;
const mask: Chunk = @splat(0x80);
if (@reduce(.Or, chunk & mask == mask)) {
// found a non ASCII code unit
break;
}
const utf16_chunk = mem.nativeToLittle(@Vector(chunk_len, u16), chunk);
utf16le[dest_index..][0..chunk_len].* = utf16_chunk;
dest_index += chunk_len;
remaining = remaining[chunk_len..];
}
}
const view = switch (surrogates) {
.cannot_encode_surrogate_half => try Utf8View.init(remaining),
.can_encode_surrogate_half => try Wtf8View.init(remaining),
};
var it = view.iterator();
while (it.nextCodepoint()) |codepoint| {
if (codepoint < 0x10000) {
utf16le[dest_index] = mem.nativeToLittle(u16, @intCast(codepoint));
dest_index += 1;
} else {
const high = @as(u16, @intCast((codepoint - 0x10000) >> 10)) + 0xD800;
const low = @as(u16, @intCast(codepoint & 0x3FF)) + 0xDC00;
utf16le[dest_index..][0..2].* = .{ mem.nativeToLittle(u16, high), mem.nativeToLittle(u16, low) };
dest_index += 2;
}
}
return dest_index;
}
test utf8ToUtf16Le {
var utf16le: [128]u16 = undefined;
{
const length = try utf8ToUtf16Le(utf16le[0..], "𐐷");
try testing.expectEqualSlices(u8, "\x01\xd8\x37\xdc", mem.sliceAsBytes(utf16le[0..length]));
}
{
const length = try utf8ToUtf16Le(utf16le[0..], "\u{10FFFF}");
try testing.expectEqualSlices(u8, "\xff\xdb\xff\xdf", mem.sliceAsBytes(utf16le[0..length]));
}
{
const result = utf8ToUtf16Le(utf16le[0..], "\xf4\x90\x80\x80");
try testing.expectError(error.InvalidUtf8, result);
}
{
const length = try utf8ToUtf16Le(utf16le[0..], "This string has been designed to test the vectorized implementat" ++
"ion by beginning with one hundred twenty-seven ASCII characters¡");
try testing.expectEqualSlices(u8, &.{
'T', 0, 'h', 0, 'i', 0, 's', 0, ' ', 0, 's', 0, 't', 0, 'r', 0, 'i', 0, 'n', 0, 'g', 0, ' ', 0, 'h', 0, 'a', 0, 's', 0, ' ', 0,
'b', 0, 'e', 0, 'e', 0, 'n', 0, ' ', 0, 'd', 0, 'e', 0, 's', 0, 'i', 0, 'g', 0, 'n', 0, 'e', 0, 'd', 0, ' ', 0, 't', 0, 'o', 0,
' ', 0, 't', 0, 'e', 0, 's', 0, 't', 0, ' ', 0, 't', 0, 'h', 0, 'e', 0, ' ', 0, 'v', 0, 'e', 0, 'c', 0, 't', 0, 'o', 0, 'r', 0,
'i', 0, 'z', 0, 'e', 0, 'd', 0, ' ', 0, 'i', 0, 'm', 0, 'p', 0, 'l', 0, 'e', 0, 'm', 0, 'e', 0, 'n', 0, 't', 0, 'a', 0, 't', 0,
'i', 0, 'o', 0, 'n', 0, ' ', 0, 'b', 0, 'y', 0, ' ', 0, 'b', 0, 'e', 0, 'g', 0, 'i', 0, 'n', 0, 'n', 0, 'i', 0, 'n', 0, 'g', 0,
' ', 0, 'w', 0, 'i', 0, 't', 0, 'h', 0, ' ', 0, 'o', 0, 'n', 0, 'e', 0, ' ', 0, 'h', 0, 'u', 0, 'n', 0, 'd', 0, 'r', 0, 'e', 0,
'd', 0, ' ', 0, 't', 0, 'w', 0, 'e', 0, 'n', 0, 't', 0, 'y', 0, '-', 0, 's', 0, 'e', 0, 'v', 0, 'e', 0, 'n', 0, ' ', 0, 'A', 0,
'S', 0, 'C', 0, 'I', 0, 'I', 0, ' ', 0, 'c', 0, 'h', 0, 'a', 0, 'r', 0, 'a', 0, 'c', 0, 't', 0, 'e', 0, 'r', 0, 's', 0, '¡', 0,
}, mem.sliceAsBytes(utf16le[0..length]));
}
}
test utf8ToUtf16LeArrayList {
{
var list = std.ArrayList(u16).init(testing.allocator);
defer list.deinit();
try utf8ToUtf16LeArrayList(&list, "𐐷");
try testing.expectEqualSlices(u8, "\x01\xd8\x37\xdc", mem.sliceAsBytes(list.items));
}
{
var list = std.ArrayList(u16).init(testing.allocator);
defer list.deinit();
try utf8ToUtf16LeArrayList(&list, "\u{10FFFF}");
try testing.expectEqualSlices(u8, "\xff\xdb\xff\xdf", mem.sliceAsBytes(list.items));
}
{
var list = std.ArrayList(u16).init(testing.allocator);
defer list.deinit();
const result = utf8ToUtf16LeArrayList(&list, "\xf4\x90\x80\x80");
try testing.expectError(error.InvalidUtf8, result);
}
}
test utf8ToUtf16LeAlloc {
{
const utf16 = try utf8ToUtf16LeAlloc(testing.allocator, "𐐷");
defer testing.allocator.free(utf16);
try testing.expectEqualSlices(u8, "\x01\xd8\x37\xdc", mem.sliceAsBytes(utf16[0..]));
}
{
const utf16 = try utf8ToUtf16LeAlloc(testing.allocator, "\u{10FFFF}");
defer testing.allocator.free(utf16);
try testing.expectEqualSlices(u8, "\xff\xdb\xff\xdf", mem.sliceAsBytes(utf16[0..]));
}
{
const result = utf8ToUtf16LeAlloc(testing.allocator, "\xf4\x90\x80\x80");
try testing.expectError(error.InvalidUtf8, result);
}
}
test utf8ToUtf16LeAllocZ {
{
const utf16 = try utf8ToUtf16LeAllocZ(testing.allocator, "𐐷");
defer testing.allocator.free(utf16);
try testing.expectEqualSlices(u8, "\x01\xd8\x37\xdc", mem.sliceAsBytes(utf16));
try testing.expect(utf16[2] == 0);
}
{
const utf16 = try utf8ToUtf16LeAllocZ(testing.allocator, "\u{10FFFF}");
defer testing.allocator.free(utf16);
try testing.expectEqualSlices(u8, "\xff\xdb\xff\xdf", mem.sliceAsBytes(utf16));
try testing.expect(utf16[2] == 0);
}
{
const result = utf8ToUtf16LeAllocZ(testing.allocator, "\xf4\x90\x80\x80");
try testing.expectError(error.InvalidUtf8, result);
}
{
const utf16 = try utf8ToUtf16LeAllocZ(testing.allocator, "This string has been designed to test the vectorized implementat" ++
"ion by beginning with one hundred twenty-seven ASCII characters¡");
defer testing.allocator.free(utf16);
try testing.expectEqualSlices(u8, &.{
'T', 0, 'h', 0, 'i', 0, 's', 0, ' ', 0, 's', 0, 't', 0, 'r', 0, 'i', 0, 'n', 0, 'g', 0, ' ', 0, 'h', 0, 'a', 0, 's', 0, ' ', 0,
'b', 0, 'e', 0, 'e', 0, 'n', 0, ' ', 0, 'd', 0, 'e', 0, 's', 0, 'i', 0, 'g', 0, 'n', 0, 'e', 0, 'd', 0, ' ', 0, 't', 0, 'o', 0,
' ', 0, 't', 0, 'e', 0, 's', 0, 't', 0, ' ', 0, 't', 0, 'h', 0, 'e', 0, ' ', 0, 'v', 0, 'e', 0, 'c', 0, 't', 0, 'o', 0, 'r', 0,
'i', 0, 'z', 0, 'e', 0, 'd', 0, ' ', 0, 'i', 0, 'm', 0, 'p', 0, 'l', 0, 'e', 0, 'm', 0, 'e', 0, 'n', 0, 't', 0, 'a', 0, 't', 0,
'i', 0, 'o', 0, 'n', 0, ' ', 0, 'b', 0, 'y', 0, ' ', 0, 'b', 0, 'e', 0, 'g', 0, 'i', 0, 'n', 0, 'n', 0, 'i', 0, 'n', 0, 'g', 0,
' ', 0, 'w', 0, 'i', 0, 't', 0, 'h', 0, ' ', 0, 'o', 0, 'n', 0, 'e', 0, ' ', 0, 'h', 0, 'u', 0, 'n', 0, 'd', 0, 'r', 0, 'e', 0,
'd', 0, ' ', 0, 't', 0, 'w', 0, 'e', 0, 'n', 0, 't', 0, 'y', 0, '-', 0, 's', 0, 'e', 0, 'v', 0, 'e', 0, 'n', 0, ' ', 0, 'A', 0,
'S', 0, 'C', 0, 'I', 0, 'I', 0, ' ', 0, 'c', 0, 'h', 0, 'a', 0, 'r', 0, 'a', 0, 'c', 0, 't', 0, 'e', 0, 'r', 0, 's', 0, '¡', 0,
}, mem.sliceAsBytes(utf16));
}
}
test "ArrayList functions on a re-used list" {
// utf8ToUtf16LeArrayList
{
var list = std.ArrayList(u16).init(testing.allocator);
defer list.deinit();
const init_slice = utf8ToUtf16LeStringLiteral("abcdefg");
try list.ensureTotalCapacityPrecise(init_slice.len);
list.appendSliceAssumeCapacity(init_slice);
try utf8ToUtf16LeArrayList(&list, "hijklmnopqrstuvwyxz");
try testing.expectEqualSlices(u16, utf8ToUtf16LeStringLiteral("abcdefghijklmnopqrstuvwyxz"), list.items);
}
// utf16LeToUtf8ArrayList
{
var list = std.ArrayList(u8).init(testing.allocator);
defer list.deinit();
const init_slice = "abcdefg";
try list.ensureTotalCapacityPrecise(init_slice.len);
list.appendSliceAssumeCapacity(init_slice);
try utf16LeToUtf8ArrayList(&list, utf8ToUtf16LeStringLiteral("hijklmnopqrstuvwyxz"));
try testing.expectEqualStrings("abcdefghijklmnopqrstuvwyxz", list.items);
}
// wtf8ToWtf16LeArrayList
{
var list = std.ArrayList(u16).init(testing.allocator);
defer list.deinit();
const init_slice = utf8ToUtf16LeStringLiteral("abcdefg");
try list.ensureTotalCapacityPrecise(init_slice.len);
list.appendSliceAssumeCapacity(init_slice);
try wtf8ToWtf16LeArrayList(&list, "hijklmnopqrstuvwyxz");
try testing.expectEqualSlices(u16, utf8ToUtf16LeStringLiteral("abcdefghijklmnopqrstuvwyxz"), list.items);
}
// wtf16LeToWtf8ArrayList
{
var list = std.ArrayList(u8).init(testing.allocator);
defer list.deinit();
const init_slice = "abcdefg";
try list.ensureTotalCapacityPrecise(init_slice.len);
list.appendSliceAssumeCapacity(init_slice);
try wtf16LeToWtf8ArrayList(&list, utf8ToUtf16LeStringLiteral("hijklmnopqrstuvwyxz"));
try testing.expectEqualStrings("abcdefghijklmnopqrstuvwyxz", list.items);
}
}
fn utf8ToUtf16LeStringLiteralImpl(comptime utf8: []const u8, comptime surrogates: Surrogates) *const [calcUtf16LeLenImpl(utf8, surrogates) catch |err| @compileError(err):0]u16 {
return comptime blk: {
const len: usize = calcUtf16LeLenImpl(utf8, surrogates) catch unreachable;
var utf16le: [len:0]u16 = [_:0]u16{0} ** len;
const utf16le_len = utf8ToUtf16LeImpl(&utf16le, utf8[0..], surrogates) catch |err| @compileError(err);
assert(len == utf16le_len);
const final = utf16le;
break :blk &final;
};
}
/// Converts a UTF-8 string literal into a UTF-16LE string literal.
pub fn utf8ToUtf16LeStringLiteral(comptime utf8: []const u8) *const [calcUtf16LeLen(utf8) catch |err| @compileError(err):0]u16 {
return utf8ToUtf16LeStringLiteralImpl(utf8, .cannot_encode_surrogate_half);
}
/// Converts a WTF-8 string literal into a WTF-16LE string literal.
pub fn wtf8ToWtf16LeStringLiteral(comptime wtf8: []const u8) *const [calcWtf16LeLen(wtf8) catch |err| @compileError(err):0]u16 {
return utf8ToUtf16LeStringLiteralImpl(wtf8, .can_encode_surrogate_half);
}
pub fn calcUtf16LeLenImpl(utf8: []const u8, comptime surrogates: Surrogates) !usize {
const utf8DecodeImpl = switch (surrogates) {
.cannot_encode_surrogate_half => utf8Decode,
.can_encode_surrogate_half => wtf8Decode,
};
var src_i: usize = 0;
var dest_len: usize = 0;
while (src_i < utf8.len) {
const n = try utf8ByteSequenceLength(utf8[src_i]);
const next_src_i = src_i + n;
const codepoint = try utf8DecodeImpl(utf8[src_i..next_src_i]);
if (codepoint < 0x10000) {
dest_len += 1;
} else {
dest_len += 2;
}
src_i = next_src_i;
}
return dest_len;
}
const CalcUtf16LeLenError = Utf8DecodeError || error{Utf8InvalidStartByte};
/// Returns length in UTF-16LE of UTF-8 slice as length of []u16.
/// Length in []u8 is 2*len16.
pub fn calcUtf16LeLen(utf8: []const u8) CalcUtf16LeLenError!usize {
return calcUtf16LeLenImpl(utf8, .cannot_encode_surrogate_half);
}
const CalcWtf16LeLenError = Wtf8DecodeError || error{Utf8InvalidStartByte};
/// Returns length in WTF-16LE of WTF-8 slice as length of []u16.
/// Length in []u8 is 2*len16.
pub fn calcWtf16LeLen(wtf8: []const u8) CalcWtf16LeLenError!usize {
return calcUtf16LeLenImpl(wtf8, .can_encode_surrogate_half);
}
fn testCalcUtf16LeLenImpl(calcUtf16LeLenImpl_: anytype) !void {
try testing.expectEqual(@as(usize, 1), try calcUtf16LeLenImpl_("a"));
try testing.expectEqual(@as(usize, 10), try calcUtf16LeLenImpl_("abcdefghij"));
try testing.expectEqual(@as(usize, 10), try calcUtf16LeLenImpl_("äåéëþüúíóö"));
try testing.expectEqual(@as(usize, 5), try calcUtf16LeLenImpl_("こんにちは"));
}
test calcUtf16LeLen {
try testCalcUtf16LeLenImpl(calcUtf16LeLen);
try comptime testCalcUtf16LeLenImpl(calcUtf16LeLen);
}
test calcWtf16LeLen {
try testCalcUtf16LeLenImpl(calcWtf16LeLen);
try comptime testCalcUtf16LeLenImpl(calcWtf16LeLen);
}
/// Print the given `utf16le` string, encoded as UTF-8 bytes.
/// Unpaired surrogates are replaced by the replacement character (U+FFFD).
fn formatUtf16Le(
utf16le: []const u16,
comptime fmt: []const u8,
options: std.fmt.FormatOptions,
writer: anytype,
) !void {
_ = fmt;
_ = options;
var buf: [300]u8 = undefined; // just an arbitrary size
var it = Utf16LeIterator.init(utf16le);
var u8len: usize = 0;
while (it.nextCodepoint() catch replacement_character) |codepoint| {
u8len += utf8Encode(codepoint, buf[u8len..]) catch
utf8Encode(replacement_character, buf[u8len..]) catch unreachable;
// make sure there's always enough room for another maximum length UTF-8 codepoint
if (u8len + 4 > buf.len) {
try writer.writeAll(buf[0..u8len]);
u8len = 0;
}
}
try writer.writeAll(buf[0..u8len]);
}
pub const fmtUtf16le = @compileError("deprecated; renamed to fmtUtf16Le");
/// Return a Formatter for a (potentially ill-formed) UTF-16 LE string,
/// which will be converted to UTF-8 during formatting.
/// Unpaired surrogates are replaced by the replacement character (U+FFFD).
pub fn fmtUtf16Le(utf16le: []const u16) std.fmt.Formatter(formatUtf16Le) {
return .{ .data = utf16le };
}
test fmtUtf16Le {
const expectFmt = testing.expectFmt;
try expectFmt("", "{}", .{fmtUtf16Le(utf8ToUtf16LeStringLiteral(""))});
try expectFmt("", "{}", .{fmtUtf16Le(wtf8ToWtf16LeStringLiteral(""))});
try expectFmt("foo", "{}", .{fmtUtf16Le(utf8ToUtf16LeStringLiteral("foo"))});
try expectFmt("foo", "{}", .{fmtUtf16Le(wtf8ToWtf16LeStringLiteral("foo"))});
try expectFmt("𐐷", "{}", .{fmtUtf16Le(wtf8ToWtf16LeStringLiteral("𐐷"))});
try expectFmt("", "{}", .{fmtUtf16Le(&[_]u16{mem.readInt(u16, "\xff\xd7", native_endian)})});
try expectFmt("<EFBFBD>", "{}", .{fmtUtf16Le(&[_]u16{mem.readInt(u16, "\x00\xd8", native_endian)})});
try expectFmt("<EFBFBD>", "{}", .{fmtUtf16Le(&[_]u16{mem.readInt(u16, "\xff\xdb", native_endian)})});
try expectFmt("<EFBFBD>", "{}", .{fmtUtf16Le(&[_]u16{mem.readInt(u16, "\x00\xdc", native_endian)})});
try expectFmt("<EFBFBD>", "{}", .{fmtUtf16Le(&[_]u16{mem.readInt(u16, "\xff\xdf", native_endian)})});
try expectFmt("", "{}", .{fmtUtf16Le(&[_]u16{mem.readInt(u16, "\x00\xe0", native_endian)})});
}
fn testUtf8ToUtf16LeStringLiteral(utf8ToUtf16LeStringLiteral_: anytype) !void {
{
const bytes = [_:0]u16{
mem.nativeToLittle(u16, 0x41),
};
const utf16 = utf8ToUtf16LeStringLiteral_("A");
try testing.expectEqualSlices(u16, &bytes, utf16);
try testing.expect(utf16[1] == 0);
}
{
const bytes = [_:0]u16{
mem.nativeToLittle(u16, 0xD801),
mem.nativeToLittle(u16, 0xDC37),
};
const utf16 = utf8ToUtf16LeStringLiteral_("𐐷");
try testing.expectEqualSlices(u16, &bytes, utf16);
try testing.expect(utf16[2] == 0);
}
{
const bytes = [_:0]u16{
mem.nativeToLittle(u16, 0x02FF),
};
const utf16 = utf8ToUtf16LeStringLiteral_("\u{02FF}");
try testing.expectEqualSlices(u16, &bytes, utf16);
try testing.expect(utf16[1] == 0);
}
{
const bytes = [_:0]u16{
mem.nativeToLittle(u16, 0x7FF),
};
const utf16 = utf8ToUtf16LeStringLiteral_("\u{7FF}");
try testing.expectEqualSlices(u16, &bytes, utf16);
try testing.expect(utf16[1] == 0);
}
{
const bytes = [_:0]u16{
mem.nativeToLittle(u16, 0x801),
};
const utf16 = utf8ToUtf16LeStringLiteral_("\u{801}");
try testing.expectEqualSlices(u16, &bytes, utf16);
try testing.expect(utf16[1] == 0);
}
{
const bytes = [_:0]u16{
mem.nativeToLittle(u16, 0xDBFF),
mem.nativeToLittle(u16, 0xDFFF),
};
const utf16 = utf8ToUtf16LeStringLiteral_("\u{10FFFF}");
try testing.expectEqualSlices(u16, &bytes, utf16);
try testing.expect(utf16[2] == 0);
}
}
test utf8ToUtf16LeStringLiteral {
try testUtf8ToUtf16LeStringLiteral(utf8ToUtf16LeStringLiteral);
}
test wtf8ToWtf16LeStringLiteral {
try testUtf8ToUtf16LeStringLiteral(wtf8ToWtf16LeStringLiteral);
}
fn testUtf8CountCodepoints() !void {
try testing.expectEqual(@as(usize, 10), try utf8CountCodepoints("abcdefghij"));
try testing.expectEqual(@as(usize, 10), try utf8CountCodepoints("äåéëþüúíóö"));
try testing.expectEqual(@as(usize, 5), try utf8CountCodepoints("こんにちは"));
// testing.expectError(error.Utf8EncodesSurrogateHalf, utf8CountCodepoints("\xED\xA0\x80"));
}
test "utf8 count codepoints" {
try testUtf8CountCodepoints();
try comptime testUtf8CountCodepoints();
}
fn testUtf8ValidCodepoint() !void {
try testing.expect(utf8ValidCodepoint('e'));
try testing.expect(utf8ValidCodepoint('ë'));
try testing.expect(utf8ValidCodepoint('は'));
try testing.expect(utf8ValidCodepoint(0xe000));
try testing.expect(utf8ValidCodepoint(0x10ffff));
try testing.expect(!utf8ValidCodepoint(0xd800));
try testing.expect(!utf8ValidCodepoint(0xdfff));
try testing.expect(!utf8ValidCodepoint(0x110000));
}
test "utf8 valid codepoint" {
try testUtf8ValidCodepoint();
try comptime testUtf8ValidCodepoint();
}
/// Returns true if the codepoint is a surrogate (U+DC00 to U+DFFF)
pub fn isSurrogateCodepoint(c: u21) bool {
return switch (c) {
0xD800...0xDFFF => true,
else => false,
};
}
/// Encodes the given codepoint into a WTF-8 byte sequence.
/// c: the codepoint.
/// out: the out buffer to write to. Must have a len >= utf8CodepointSequenceLength(c).
/// Errors: if c cannot be encoded in WTF-8.
/// Returns: the number of bytes written to out.
pub fn wtf8Encode(c: u21, out: []u8) error{CodepointTooLarge}!u3 {
return utf8EncodeImpl(c, out, .can_encode_surrogate_half);
}
const Wtf8DecodeError = Utf8Decode2Error || Utf8Decode3AllowSurrogateHalfError || Utf8Decode4Error;
/// Deprecated. This function has an awkward API that is too easy to use incorrectly.
pub fn wtf8Decode(bytes: []const u8) Wtf8DecodeError!u21 {
return switch (bytes.len) {
1 => bytes[0],
2 => utf8Decode2(bytes[0..2].*),
3 => utf8Decode3AllowSurrogateHalf(bytes[0..3].*),
4 => utf8Decode4(bytes[0..4].*),
else => unreachable,
};
}
/// Returns true if the input consists entirely of WTF-8 codepoints
/// (all the same restrictions as UTF-8, but allows surrogate codepoints
/// U+D800 to U+DFFF).
/// Does not check for well-formed WTF-8, meaning that this function
/// does not check that all surrogate halves are unpaired.
pub fn wtf8ValidateSlice(input: []const u8) bool {
return utf8ValidateSliceImpl(input, .can_encode_surrogate_half);
}
test "validate WTF-8 slice" {
try testValidateWtf8Slice();
try comptime testValidateWtf8Slice();
// We skip a variable (based on recommended vector size) chunks of
// ASCII characters. Let's make sure we're chunking correctly.
const str = [_]u8{'a'} ** 550 ++ "\xc0";
for (0..str.len - 3) |i| {
try testing.expect(!wtf8ValidateSlice(str[i..]));
}
}
fn testValidateWtf8Slice() !void {
// These are valid/invalid under both UTF-8 and WTF-8 rules.
try testing.expect(wtf8ValidateSlice("abc"));
try testing.expect(wtf8ValidateSlice("abc\xdf\xbf"));
try testing.expect(wtf8ValidateSlice(""));
try testing.expect(wtf8ValidateSlice("a"));
try testing.expect(wtf8ValidateSlice("abc"));
try testing.expect(wtf8ValidateSlice("Ж"));
try testing.expect(wtf8ValidateSlice("ЖЖ"));
try testing.expect(wtf8ValidateSlice("брэд-ЛГТМ"));
try testing.expect(wtf8ValidateSlice("☺☻☹"));
try testing.expect(wtf8ValidateSlice("a\u{fffdb}"));
try testing.expect(wtf8ValidateSlice("\xf4\x8f\xbf\xbf"));
try testing.expect(wtf8ValidateSlice("abc\xdf\xbf"));
try testing.expect(!wtf8ValidateSlice("abc\xc0"));
try testing.expect(!wtf8ValidateSlice("abc\xc0abc"));
try testing.expect(!wtf8ValidateSlice("aa\xe2"));
try testing.expect(!wtf8ValidateSlice("\x42\xfa"));
try testing.expect(!wtf8ValidateSlice("\x42\xfa\x43"));
try testing.expect(!wtf8ValidateSlice("abc\xc0"));
try testing.expect(!wtf8ValidateSlice("abc\xc0abc"));
try testing.expect(!wtf8ValidateSlice("\xf4\x90\x80\x80"));
try testing.expect(!wtf8ValidateSlice("\xf7\xbf\xbf\xbf"));
try testing.expect(!wtf8ValidateSlice("\xfb\xbf\xbf\xbf\xbf"));
try testing.expect(!wtf8ValidateSlice("\xc0\x80"));
// But surrogate codepoints are only valid in WTF-8.
try testing.expect(wtf8ValidateSlice("\xed\xa0\x80"));
try testing.expect(wtf8ValidateSlice("\xed\xbf\xbf"));
}
/// Wtf8View iterates the code points of a WTF-8 encoded string,
/// including surrogate halves.
///
/// ```
/// var wtf8 = (try std.unicode.Wtf8View.init("hi there")).iterator();
/// while (wtf8.nextCodepointSlice()) |codepoint| {
/// // note: codepoint could be a surrogate half which is invalid
/// // UTF-8, avoid printing or otherwise sending/emitting this directly
/// }
/// ```
pub const Wtf8View = struct {
bytes: []const u8,
pub fn init(s: []const u8) error{InvalidWtf8}!Wtf8View {
if (!wtf8ValidateSlice(s)) {
return error.InvalidWtf8;
}
return initUnchecked(s);
}
pub fn initUnchecked(s: []const u8) Wtf8View {
return Wtf8View{ .bytes = s };
}
pub inline fn initComptime(comptime s: []const u8) Wtf8View {
return comptime if (init(s)) |r| r else |err| switch (err) {
error.InvalidWtf8 => {
@compileError("invalid wtf8");
},
};
}
pub fn iterator(s: Wtf8View) Wtf8Iterator {
return Wtf8Iterator{
.bytes = s.bytes,
.i = 0,
};
}
};
/// Asserts that `bytes` is valid WTF-8
pub const Wtf8Iterator = struct {
bytes: []const u8,
i: usize,
pub fn nextCodepointSlice(it: *Wtf8Iterator) ?[]const u8 {
if (it.i >= it.bytes.len) {
return null;
}
const cp_len = utf8ByteSequenceLength(it.bytes[it.i]) catch unreachable;
it.i += cp_len;
return it.bytes[it.i - cp_len .. it.i];
}
pub fn nextCodepoint(it: *Wtf8Iterator) ?u21 {
const slice = it.nextCodepointSlice() orelse return null;
return wtf8Decode(slice) catch unreachable;
}
/// Look ahead at the next n codepoints without advancing the iterator.
/// If fewer than n codepoints are available, then return the remainder of the string.
pub fn peek(it: *Wtf8Iterator, n: usize) []const u8 {
const original_i = it.i;
defer it.i = original_i;
var end_ix = original_i;
var found: usize = 0;
while (found < n) : (found += 1) {
const next_codepoint = it.nextCodepointSlice() orelse return it.bytes[original_i..];
end_ix += next_codepoint.len;
}
return it.bytes[original_i..end_ix];
}
};
pub fn wtf16LeToWtf8ArrayList(result: *std.ArrayList(u8), utf16le: []const u16) mem.Allocator.Error!void {
try result.ensureUnusedCapacity(utf16le.len);
return utf16LeToUtf8ArrayListImpl(result, utf16le, .can_encode_surrogate_half);
}
/// Caller must free returned memory.
pub fn wtf16LeToWtf8Alloc(allocator: mem.Allocator, wtf16le: []const u16) mem.Allocator.Error![]u8 {
// optimistically guess that it will all be ascii.
var result = try std.ArrayList(u8).initCapacity(allocator, wtf16le.len);
errdefer result.deinit();
try utf16LeToUtf8ArrayListImpl(&result, wtf16le, .can_encode_surrogate_half);
return result.toOwnedSlice();
}
/// Caller must free returned memory.
pub fn wtf16LeToWtf8AllocZ(allocator: mem.Allocator, wtf16le: []const u16) mem.Allocator.Error![:0]u8 {
// optimistically guess that it will all be ascii (and allocate space for the null terminator)
var result = try std.ArrayList(u8).initCapacity(allocator, wtf16le.len + 1);
errdefer result.deinit();
try utf16LeToUtf8ArrayListImpl(&result, wtf16le, .can_encode_surrogate_half);
return result.toOwnedSliceSentinel(0);
}
pub fn wtf16LeToWtf8(wtf8: []u8, wtf16le: []const u16) usize {
return utf16LeToUtf8Impl(wtf8, wtf16le, .can_encode_surrogate_half) catch |err| switch (err) {};
}
pub fn wtf8ToWtf16LeArrayList(result: *std.ArrayList(u16), wtf8: []const u8) error{ InvalidWtf8, OutOfMemory }!void {
try result.ensureUnusedCapacity(wtf8.len);
return utf8ToUtf16LeArrayListImpl(result, wtf8, .can_encode_surrogate_half);
}
pub fn wtf8ToWtf16LeAlloc(allocator: mem.Allocator, wtf8: []const u8) error{ InvalidWtf8, OutOfMemory }![]u16 {
// optimistically guess that it will not require surrogate pairs
var result = try std.ArrayList(u16).initCapacity(allocator, wtf8.len);
errdefer result.deinit();
try utf8ToUtf16LeArrayListImpl(&result, wtf8, .can_encode_surrogate_half);
return result.toOwnedSlice();
}
pub fn wtf8ToWtf16LeAllocZ(allocator: mem.Allocator, wtf8: []const u8) error{ InvalidWtf8, OutOfMemory }![:0]u16 {
// optimistically guess that it will not require surrogate pairs
var result = try std.ArrayList(u16).initCapacity(allocator, wtf8.len + 1);
errdefer result.deinit();
try utf8ToUtf16LeArrayListImpl(&result, wtf8, .can_encode_surrogate_half);
return result.toOwnedSliceSentinel(0);
}
/// Returns index of next character. If exact fit, returned index equals output slice length.
/// Assumes there is enough space for the output.
pub fn wtf8ToWtf16Le(wtf16le: []u16, wtf8: []const u8) error{InvalidWtf8}!usize {
return utf8ToUtf16LeImpl(wtf16le, wtf8, .can_encode_surrogate_half);
}
fn checkUtf8ToUtf16LeOverflowImpl(utf8: []const u8, utf16le: []const u16, comptime surrogates: Surrogates) !bool {
// Each u8 in UTF-8/WTF-8 correlates to at most one u16 in UTF-16LE/WTF-16LE.
if (utf16le.len >= utf8.len) return false;
const utf16_len = calcUtf16LeLenImpl(utf8, surrogates) catch {
return switch (surrogates) {
.cannot_encode_surrogate_half => error.InvalidUtf8,
.can_encode_surrogate_half => error.InvalidWtf8,
};
};
return utf16_len > utf16le.len;
}
/// Checks if calling `utf8ToUtf16Le` would overflow. Might fail if utf8 is not
/// valid UTF-8.
pub fn checkUtf8ToUtf16LeOverflow(utf8: []const u8, utf16le: []const u16) error{InvalidUtf8}!bool {
return checkUtf8ToUtf16LeOverflowImpl(utf8, utf16le, .cannot_encode_surrogate_half);
}
/// Checks if calling `utf8ToUtf16Le` would overflow. Might fail if wtf8 is not
/// valid WTF-8.
pub fn checkWtf8ToWtf16LeOverflow(wtf8: []const u8, wtf16le: []const u16) error{InvalidWtf8}!bool {
return checkUtf8ToUtf16LeOverflowImpl(wtf8, wtf16le, .can_encode_surrogate_half);
}
/// Surrogate codepoints (U+D800 to U+DFFF) are replaced by the Unicode replacement
/// character (U+FFFD).
/// All surrogate codepoints and the replacement character are encoded as three
/// bytes, meaning the input and output slices will always be the same length.
/// In-place conversion is supported when `utf8` and `wtf8` refer to the same slice.
/// Note: If `wtf8` is entirely composed of well-formed UTF-8, then no conversion is necessary.
/// `utf8ValidateSlice` can be used to check if lossy conversion is worthwhile.
/// If `wtf8` is not valid WTF-8, then `error.InvalidWtf8` is returned.
pub fn wtf8ToUtf8Lossy(utf8: []u8, wtf8: []const u8) error{InvalidWtf8}!void {
assert(utf8.len >= wtf8.len);
const in_place = utf8.ptr == wtf8.ptr;
const replacement_char_bytes = comptime blk: {
var buf: [3]u8 = undefined;
assert((utf8Encode(replacement_character, &buf) catch unreachable) == 3);
break :blk buf;
};
var dest_i: usize = 0;
const view = try Wtf8View.init(wtf8);
var it = view.iterator();
while (it.nextCodepointSlice()) |codepoint_slice| {
// All surrogate codepoints are encoded as 3 bytes
if (codepoint_slice.len == 3) {
const codepoint = wtf8Decode(codepoint_slice) catch unreachable;
if (isSurrogateCodepoint(codepoint)) {
@memcpy(utf8[dest_i..][0..replacement_char_bytes.len], &replacement_char_bytes);
dest_i += replacement_char_bytes.len;
continue;
}
}
if (!in_place) {
@memcpy(utf8[dest_i..][0..codepoint_slice.len], codepoint_slice);
}
dest_i += codepoint_slice.len;
}
}
pub fn wtf8ToUtf8LossyAlloc(allocator: mem.Allocator, wtf8: []const u8) error{ InvalidWtf8, OutOfMemory }![]u8 {
const utf8 = try allocator.alloc(u8, wtf8.len);
errdefer allocator.free(utf8);
try wtf8ToUtf8Lossy(utf8, wtf8);
return utf8;
}
pub fn wtf8ToUtf8LossyAllocZ(allocator: mem.Allocator, wtf8: []const u8) error{ InvalidWtf8, OutOfMemory }![:0]u8 {
const utf8 = try allocator.allocSentinel(u8, wtf8.len, 0);
errdefer allocator.free(utf8);
try wtf8ToUtf8Lossy(utf8, wtf8);
return utf8;
}
test wtf8ToUtf8Lossy {
var buf: [32]u8 = undefined;
const invalid_utf8 = "\xff";
try testing.expectError(error.InvalidWtf8, wtf8ToUtf8Lossy(&buf, invalid_utf8));
const ascii = "abcd";
try wtf8ToUtf8Lossy(&buf, ascii);
try testing.expectEqualStrings("abcd", buf[0..ascii.len]);
const high_surrogate_half = "ab\xed\xa0\xbdcd";
try wtf8ToUtf8Lossy(&buf, high_surrogate_half);
try testing.expectEqualStrings("ab\u{FFFD}cd", buf[0..high_surrogate_half.len]);
const low_surrogate_half = "ab\xed\xb2\xa9cd";
try wtf8ToUtf8Lossy(&buf, low_surrogate_half);
try testing.expectEqualStrings("ab\u{FFFD}cd", buf[0..low_surrogate_half.len]);
// If the WTF-8 is not well-formed, each surrogate half is converted into a separate
// replacement character instead of being interpreted as a surrogate pair.
const encoded_surrogate_pair = "ab\xed\xa0\xbd\xed\xb2\xa9cd";
try wtf8ToUtf8Lossy(&buf, encoded_surrogate_pair);
try testing.expectEqualStrings("ab\u{FFFD}\u{FFFD}cd", buf[0..encoded_surrogate_pair.len]);
// in place
@memcpy(buf[0..low_surrogate_half.len], low_surrogate_half);
const slice = buf[0..low_surrogate_half.len];
try wtf8ToUtf8Lossy(slice, slice);
try testing.expectEqualStrings("ab\u{FFFD}cd", slice);
}
test wtf8ToUtf8LossyAlloc {
const invalid_utf8 = "\xff";
try testing.expectError(error.InvalidWtf8, wtf8ToUtf8LossyAlloc(testing.allocator, invalid_utf8));
{
const ascii = "abcd";
const utf8 = try wtf8ToUtf8LossyAlloc(testing.allocator, ascii);
defer testing.allocator.free(utf8);
try testing.expectEqualStrings("abcd", utf8);
}
{
const surrogate_half = "ab\xed\xa0\xbdcd";
const utf8 = try wtf8ToUtf8LossyAlloc(testing.allocator, surrogate_half);
defer testing.allocator.free(utf8);
try testing.expectEqualStrings("ab\u{FFFD}cd", utf8);
}
{
// If the WTF-8 is not well-formed, each surrogate half is converted into a separate
// replacement character instead of being interpreted as a surrogate pair.
const encoded_surrogate_pair = "ab\xed\xa0\xbd\xed\xb2\xa9cd";
const utf8 = try wtf8ToUtf8LossyAlloc(testing.allocator, encoded_surrogate_pair);
defer testing.allocator.free(utf8);
try testing.expectEqualStrings("ab\u{FFFD}\u{FFFD}cd", utf8);
}
}
test wtf8ToUtf8LossyAllocZ {
const invalid_utf8 = "\xff";
try testing.expectError(error.InvalidWtf8, wtf8ToUtf8LossyAllocZ(testing.allocator, invalid_utf8));
{
const ascii = "abcd";
const utf8 = try wtf8ToUtf8LossyAllocZ(testing.allocator, ascii);
defer testing.allocator.free(utf8);
try testing.expectEqualStrings("abcd", utf8);
}
{
const surrogate_half = "ab\xed\xa0\xbdcd";
const utf8 = try wtf8ToUtf8LossyAllocZ(testing.allocator, surrogate_half);
defer testing.allocator.free(utf8);
try testing.expectEqualStrings("ab\u{FFFD}cd", utf8);
}
{
// If the WTF-8 is not well-formed, each surrogate half is converted into a separate
// replacement character instead of being interpreted as a surrogate pair.
const encoded_surrogate_pair = "ab\xed\xa0\xbd\xed\xb2\xa9cd";
const utf8 = try wtf8ToUtf8LossyAllocZ(testing.allocator, encoded_surrogate_pair);
defer testing.allocator.free(utf8);
try testing.expectEqualStrings("ab\u{FFFD}\u{FFFD}cd", utf8);
}
}
pub const Wtf16LeIterator = struct {
bytes: []const u8,
i: usize,
pub fn init(s: []const u16) Wtf16LeIterator {
return Wtf16LeIterator{
.bytes = mem.sliceAsBytes(s),
.i = 0,
};
}
/// If the next codepoint is encoded by a surrogate pair, returns the
/// codepoint that the surrogate pair represents.
/// If the next codepoint is an unpaired surrogate, returns the codepoint
/// of the unpaired surrogate.
pub fn nextCodepoint(it: *Wtf16LeIterator) ?u21 {
assert(it.i <= it.bytes.len);
if (it.i == it.bytes.len) return null;
var code_units: [2]u16 = undefined;
code_units[0] = mem.readInt(u16, it.bytes[it.i..][0..2], .little);
it.i += 2;
surrogate_pair: {
if (utf16IsHighSurrogate(code_units[0])) {
if (it.i >= it.bytes.len) break :surrogate_pair;
code_units[1] = mem.readInt(u16, it.bytes[it.i..][0..2], .little);
const codepoint = utf16DecodeSurrogatePair(&code_units) catch break :surrogate_pair;
it.i += 2;
return codepoint;
}
}
return code_units[0];
}
};
test "non-well-formed WTF-8 does not roundtrip" {
// This encodes the surrogate pair U+D83D U+DCA9.
// The well-formed version of this would be U+1F4A9 which is \xF0\x9F\x92\xA9.
const non_well_formed_wtf8 = "\xed\xa0\xbd\xed\xb2\xa9";
var wtf16_buf: [2]u16 = undefined;
const wtf16_len = try wtf8ToWtf16Le(&wtf16_buf, non_well_formed_wtf8);
const wtf16 = wtf16_buf[0..wtf16_len];
try testing.expectEqualSlices(u16, &[_]u16{
mem.nativeToLittle(u16, 0xD83D), // high surrogate
mem.nativeToLittle(u16, 0xDCA9), // low surrogate
}, wtf16);
var wtf8_buf: [4]u8 = undefined;
const wtf8_len = wtf16LeToWtf8(&wtf8_buf, wtf16);
const wtf8 = wtf8_buf[0..wtf8_len];
// Converting to WTF-16 and back results in well-formed WTF-8,
// but it does not match the input WTF-8
try testing.expectEqualSlices(u8, "\xf0\x9f\x92\xa9", wtf8);
}
fn testRoundtripWtf8(wtf8: []const u8) !void {
// Buffer
{
var wtf16_buf: [32]u16 = undefined;
const wtf16_len = try wtf8ToWtf16Le(&wtf16_buf, wtf8);
try testing.expectEqual(wtf16_len, calcWtf16LeLen(wtf8));
try testing.expectEqual(false, checkWtf8ToWtf16LeOverflow(wtf8, &wtf16_buf));
const wtf16 = wtf16_buf[0..wtf16_len];
var roundtripped_buf: [32]u8 = undefined;
const roundtripped_len = wtf16LeToWtf8(&roundtripped_buf, wtf16);
const roundtripped = roundtripped_buf[0..roundtripped_len];
try testing.expectEqualSlices(u8, wtf8, roundtripped);
}
// Alloc
{
const wtf16 = try wtf8ToWtf16LeAlloc(testing.allocator, wtf8);
defer testing.allocator.free(wtf16);
const roundtripped = try wtf16LeToWtf8Alloc(testing.allocator, wtf16);
defer testing.allocator.free(roundtripped);
try testing.expectEqualSlices(u8, wtf8, roundtripped);
}
// AllocZ
{
const wtf16 = try wtf8ToWtf16LeAllocZ(testing.allocator, wtf8);
defer testing.allocator.free(wtf16);
const roundtripped = try wtf16LeToWtf8AllocZ(testing.allocator, wtf16);
defer testing.allocator.free(roundtripped);
try testing.expectEqualSlices(u8, wtf8, roundtripped);
}
}
test "well-formed WTF-8 roundtrips" {
try testRoundtripWtf8("\xed\x9f\xbf"); // not a surrogate half
try testRoundtripWtf8("\xed\xa0\xbd"); // high surrogate
try testRoundtripWtf8("\xed\xb2\xa9"); // low surrogate
try testRoundtripWtf8("\xed\xa0\xbd \xed\xb2\xa9"); // <high surrogate><space><low surrogate>
try testRoundtripWtf8("\xed\xa0\x80\xed\xaf\xbf"); // <high surrogate><high surrogate>
try testRoundtripWtf8("\xed\xa0\x80\xee\x80\x80"); // <high surrogate><not surrogate>
try testRoundtripWtf8("\xed\x9f\xbf\xed\xb0\x80"); // <not surrogate><low surrogate>
try testRoundtripWtf8("a\xed\xb0\x80"); // <not surrogate><low surrogate>
try testRoundtripWtf8("\xf0\x9f\x92\xa9"); // U+1F4A9, encoded as a surrogate pair in WTF-16
}
fn testRoundtripWtf16(wtf16le: []const u16) !void {
// Buffer
{
var wtf8_buf: [32]u8 = undefined;
const wtf8_len = wtf16LeToWtf8(&wtf8_buf, wtf16le);
const wtf8 = wtf8_buf[0..wtf8_len];
var roundtripped_buf: [32]u16 = undefined;
const roundtripped_len = try wtf8ToWtf16Le(&roundtripped_buf, wtf8);
const roundtripped = roundtripped_buf[0..roundtripped_len];
try testing.expectEqualSlices(u16, wtf16le, roundtripped);
}
// Alloc
{
const wtf8 = try wtf16LeToWtf8Alloc(testing.allocator, wtf16le);
defer testing.allocator.free(wtf8);
const roundtripped = try wtf8ToWtf16LeAlloc(testing.allocator, wtf8);
defer testing.allocator.free(roundtripped);
try testing.expectEqualSlices(u16, wtf16le, roundtripped);
}
// AllocZ
{
const wtf8 = try wtf16LeToWtf8AllocZ(testing.allocator, wtf16le);
defer testing.allocator.free(wtf8);
const roundtripped = try wtf8ToWtf16LeAllocZ(testing.allocator, wtf8);
defer testing.allocator.free(roundtripped);
try testing.expectEqualSlices(u16, wtf16le, roundtripped);
}
}
test "well-formed WTF-16 roundtrips" {
try testRoundtripWtf16(&[_]u16{
mem.nativeToLittle(u16, 0xD83D), // high surrogate
mem.nativeToLittle(u16, 0xDCA9), // low surrogate
});
try testRoundtripWtf16(&[_]u16{
mem.nativeToLittle(u16, 0xD83D), // high surrogate
mem.nativeToLittle(u16, ' '), // not surrogate
mem.nativeToLittle(u16, 0xDCA9), // low surrogate
});
try testRoundtripWtf16(&[_]u16{
mem.nativeToLittle(u16, 0xD800), // high surrogate
mem.nativeToLittle(u16, 0xDBFF), // high surrogate
});
try testRoundtripWtf16(&[_]u16{
mem.nativeToLittle(u16, 0xD800), // high surrogate
mem.nativeToLittle(u16, 0xE000), // not surrogate
});
try testRoundtripWtf16(&[_]u16{
mem.nativeToLittle(u16, 0xD7FF), // not surrogate
mem.nativeToLittle(u16, 0xDC00), // low surrogate
});
try testRoundtripWtf16(&[_]u16{
mem.nativeToLittle(u16, 0x61), // not surrogate
mem.nativeToLittle(u16, 0xDC00), // low surrogate
});
try testRoundtripWtf16(&[_]u16{
mem.nativeToLittle(u16, 0xDC00), // low surrogate
});
}
/// Returns the length, in bytes, that would be necessary to encode the
/// given WTF-16 LE slice as WTF-8.
pub fn calcWtf8Len(wtf16le: []const u16) usize {
var it = Wtf16LeIterator.init(wtf16le);
var num_wtf8_bytes: usize = 0;
while (it.nextCodepoint()) |codepoint| {
// Note: If utf8CodepointSequenceLength is ever changed to error on surrogate
// codepoints, then it would no longer be eligible to be used in this context.
num_wtf8_bytes += utf8CodepointSequenceLength(codepoint) catch |err| switch (err) {
error.CodepointTooLarge => unreachable,
};
}
return num_wtf8_bytes;
}
fn testCalcWtf8Len() !void {
const L = utf8ToUtf16LeStringLiteral;
try testing.expectEqual(@as(usize, 1), calcWtf8Len(L("a")));
try testing.expectEqual(@as(usize, 10), calcWtf8Len(L("abcdefghij")));
// unpaired surrogate
try testing.expectEqual(@as(usize, 3), calcWtf8Len(&[_]u16{
mem.nativeToLittle(u16, 0xD800),
}));
try testing.expectEqual(@as(usize, 15), calcWtf8Len(L("こんにちは")));
// First codepoints that are encoded as 1, 2, 3, and 4 bytes
try testing.expectEqual(@as(usize, 1 + 2 + 3 + 4), calcWtf8Len(L("\u{0}\u{80}\u{800}\u{10000}")));
}
test "calculate wtf8 string length of given wtf16 string" {
try testCalcWtf8Len();
try comptime testCalcWtf8Len();
}