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Add type-erased writer and GenericWriter

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This is a companion to #17344 to apply the same change to the
`std.io.Writer` interface.
This commit is contained in:
Ian Johnson 2023-10-09 00:10:30 -04:00
parent 4dfca01de4
commit e392c1a0b3
4 changed files with 123 additions and 70 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
CMakeLists.txt
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@ -265,7 +265,7 @@ set(ZIG_STAGE2_SOURCES
"${CMAKE_SOURCE_DIR}/lib/std/io/limited_reader.zig"
"${CMAKE_SOURCE_DIR}/lib/std/io/Reader.zig"
"${CMAKE_SOURCE_DIR}/lib/std/io/seekable_stream.zig"
"${CMAKE_SOURCE_DIR}/lib/std/io/writer.zig"
"${CMAKE_SOURCE_DIR}/lib/std/io/Writer.zig"
"${CMAKE_SOURCE_DIR}/lib/std/json.zig"
"${CMAKE_SOURCE_DIR}/lib/std/json/stringify.zig"
"${CMAKE_SOURCE_DIR}/lib/std/leb128.zig"

64
lib/std/io.zig
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@ -333,13 +333,73 @@ pub fn GenericReader(
};
}
pub fn GenericWriter(
comptime Context: type,
comptime WriteError: type,
comptime writeFn: fn (context: Context, bytes: []const u8) WriteError!usize,
) type {
return struct {
context: Context,
const Self = @This();
pub const Error = WriteError;
pub inline fn write(self: Self, bytes: []const u8) Error!usize {
return writeFn(self.context, bytes);
}
pub inline fn writeAll(self: Self, bytes: []const u8) Error!void {
return @errorCast(self.any().writeAll(bytes));
}
pub inline fn print(self: Self, comptime format: []const u8, args: anytype) Error!void {
return @errorCast(self.any().print(format, args));
}
pub inline fn writeByte(self: Self, byte: u8) Error!void {
return @errorCast(self.any().writeByte(byte));
}
pub inline fn writeByteNTimes(self: Self, byte: u8, n: usize) Error!void {
return @errorCast(self.any().writeByteNTimes(byte, n));
}
pub inline fn writeBytesNTimes(self: Self, bytes: []const u8, n: usize) Error!void {
return @errorCast(self.any().writeBytesNTimes(bytes, n));
}
pub inline fn writeInt(self: Self, comptime T: type, value: T, endian: std.builtin.Endian) Error!void {
return @errorCast(self.any().writeInt(T, value, endian));
}
pub inline fn writeStruct(self: Self, value: anytype) Error!void {
return @errorCast(self.any().writeStruct(value));
}
pub inline fn any(self: *const Self) AnyWriter {
return .{
.context = @ptrCast(&self.context),
.writeFn = typeErasedWriteFn,
};
}
fn typeErasedWriteFn(context: *const anyopaque, bytes: []const u8) anyerror!usize {
const ptr: *const Context = @alignCast(@ptrCast(context));
return writeFn(ptr.*, bytes);
}
};
}
/// Deprecated; consider switching to `AnyReader` or use `GenericReader`
/// to use previous API.
pub const Reader = GenericReader;
/// Deprecated; consider switching to `AnyWriter` or use `GenericWriter`
/// to use previous API.
pub const Writer = GenericWriter;
pub const AnyReader = @import("io/Reader.zig");
pub const AnyWriter = @import("io/Writer.zig");
pub const Writer = @import("io/writer.zig").Writer;
pub const SeekableStream = @import("io/seekable_stream.zig").SeekableStream;
pub const BufferedWriter = @import("io/buffered_writer.zig").BufferedWriter;
@ -652,6 +712,7 @@ pub fn PollFiles(comptime StreamEnum: type) type {
test {
_ = AnyReader;
_ = AnyWriter;
_ = @import("io/bit_reader.zig");
_ = @import("io/bit_writer.zig");
_ = @import("io/buffered_atomic_file.zig");
@ -661,7 +722,6 @@ test {
_ = @import("io/counting_writer.zig");
_ = @import("io/counting_reader.zig");
_ = @import("io/fixed_buffer_stream.zig");
_ = @import("io/writer.zig");
_ = @import("io/peek_stream.zig");
_ = @import("io/seekable_stream.zig");
_ = @import("io/stream_source.zig");

60
lib/std/io/Writer.zig Normal file
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@ -0,0 +1,60 @@
const std = @import("../std.zig");
const assert = std.debug.assert;
const mem = std.mem;
context: *const anyopaque,
writeFn: *const fn (context: *const anyopaque, bytes: []const u8) anyerror!usize,
const Self = @This();
pub const Error = anyerror;
pub fn write(self: Self, bytes: []const u8) anyerror!usize {
return self.writeFn(self.context, bytes);
}
pub fn writeAll(self: Self, bytes: []const u8) anyerror!void {
var index: usize = 0;
while (index != bytes.len) {
index += try self.write(bytes[index..]);
}
}
pub fn print(self: Self, comptime format: []const u8, args: anytype) anyerror!void {
return std.fmt.format(self, format, args);
}
pub fn writeByte(self: Self, byte: u8) anyerror!void {
const array = [1]u8{byte};
return self.writeAll(&array);
}
pub fn writeByteNTimes(self: Self, byte: u8, n: usize) anyerror!void {
var bytes: [256]u8 = undefined;
@memset(bytes[0..], byte);
var remaining: usize = n;
while (remaining > 0) {
const to_write = @min(remaining, bytes.len);
try self.writeAll(bytes[0..to_write]);
remaining -= to_write;
}
}
pub fn writeBytesNTimes(self: Self, bytes: []const u8, n: usize) anyerror!void {
var i: usize = 0;
while (i < n) : (i += 1) {
try self.writeAll(bytes);
}
}
pub inline fn writeInt(self: Self, comptime T: type, value: T, endian: std.builtin.Endian) anyerror!void {
var bytes: [@divExact(@typeInfo(T).Int.bits, 8)]u8 = undefined;
mem.writeInt(std.math.ByteAlignedInt(@TypeOf(value)), &bytes, value, endian);
return self.writeAll(&bytes);
}
pub fn writeStruct(self: Self, value: anytype) anyerror!void {
// Only extern and packed structs have defined in-memory layout.
comptime assert(@typeInfo(@TypeOf(value)).Struct.layout != .Auto);
return self.writeAll(mem.asBytes(&value));
}

67
lib/std/io/writer.zig
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@ -1,67 +0,0 @@
const std = @import("../std.zig");
const assert = std.debug.assert;
const mem = std.mem;
pub fn Writer(
comptime Context: type,
comptime WriteError: type,
comptime writeFn: fn (context: Context, bytes: []const u8) WriteError!usize,
) type {
return struct {
context: Context,
const Self = @This();
pub const Error = WriteError;
pub fn write(self: Self, bytes: []const u8) Error!usize {
return writeFn(self.context, bytes);
}
pub fn writeAll(self: Self, bytes: []const u8) Error!void {
var index: usize = 0;
while (index != bytes.len) {
index += try self.write(bytes[index..]);
}
}
pub fn print(self: Self, comptime format: []const u8, args: anytype) Error!void {
return std.fmt.format(self, format, args);
}
pub fn writeByte(self: Self, byte: u8) Error!void {
const array = [1]u8{byte};
return self.writeAll(&array);
}
pub fn writeByteNTimes(self: Self, byte: u8, n: usize) Error!void {
var bytes: [256]u8 = undefined;
@memset(bytes[0..], byte);
var remaining: usize = n;
while (remaining > 0) {
const to_write = @min(remaining, bytes.len);
try self.writeAll(bytes[0..to_write]);
remaining -= to_write;
}
}
pub fn writeBytesNTimes(self: Self, bytes: []const u8, n: usize) Error!void {
var i: usize = 0;
while (i < n) : (i += 1) {
try self.writeAll(bytes);
}
}
pub inline fn writeInt(self: Self, comptime T: type, value: T, endian: std.builtin.Endian) Error!void {
var bytes: [@divExact(@typeInfo(T).Int.bits, 8)]u8 = undefined;
mem.writeInt(std.math.ByteAlignedInt(@TypeOf(value)), &bytes, value, endian);
return self.writeAll(&bytes);
}
pub fn writeStruct(self: Self, value: anytype) Error!void {
// Only extern and packed structs have defined in-memory layout.
comptime assert(@typeInfo(@TypeOf(value)).Struct.layout != .Auto);
return self.writeAll(mem.asBytes(&value));
}
};
}