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zig source #1

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Source code

const std = @import("std");

const Writer = struct {
    buffer: []u8,
    tail: usize = 0,
    vtable: *const struct { flush: *const fn (ptr: *Writer) void },
    pub fn write_byte(self: *Writer, byte: u8) void {
        if (self.tail == self.buffer.len) {
            self.vtable.flush(self);
            self.tail = 0;
        }

self.buffer[self.tail] = byte;
        self.tail += 1;
    }
    pub fn flush(self: *Writer) void {
        self.vtable.flush(self);
    }
};

const File = struct { handle: std.posix.fd_t, writer: Writer };
fn flush(ptr: *Writer) void {
    const self: *File = @fieldParentPtr("writer", ptr);
    _ = std.posix.write(self.handle, ptr.buffer[0..ptr.tail]) catch unreachable;
}
pub fn main() !void {
    var buffer: [5]u8 = undefined;
    var stdout: File = .{
        .handle = 1,
        .writer = .{ .vtable = &.{ .flush = flush }, .buffer = buffer[0..] },
    };
    var writer = &stdout.writer;
    writer.write_byte('H');
    writer.write_byte('e');
    writer.write_byte('l');
    writer.write_byte('l');
    writer.write_byte('o');
    writer.write_byte('w');
    writer.write_byte('o');
    writer.write_byte('r');
    writer.write_byte('l');
    writer.write_byte('d');
    writer.write_byte('\n');
    writer.write_byte('w');
    writer.write_byte('o');
    writer.write_byte('r');
    writer.write_byte('w');
    writer.write_byte('w');
    writer.write_byte('w');
    writer.write_byte('o');
    writer.write_byte('r');
    writer.write_byte('o');
    writer.write_byte('r');
    writer.write_byte('o');
    writer.write_byte('r');
    writer.flush();
}

zig source #2

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Source code

const std = @import("std");

const Writer = struct {
    ptr: *anyopaque,
    vtable: *const struct { 
        flush: *const fn (ptr: *anyopaque) void,
        write_byte: *const fn (ptr: *anyopaque, byte: u8) void,
    },
    pub fn write_byte(self: @This(), byte: u8) void {
        self.vtable.write_byte(self.ptr, byte);
    }
    pub fn flush(self: @This()) void {
        self.vtable.flush(self.ptr);
    }
};

const File = struct { 
    handle: std.posix.fd_t,
    buffer: []u8,
    tail: usize = 0,
};
fn flush(ptr: *anyopaque) void {
    const file: *File = @ptrCast(@alignCast(ptr));
    _ = std.posix.write(file.handle, file.buffer[0..file.tail]) catch unreachable;
}
fn write_byte(ptr: *anyopaque, byte: u8) void {
    const file: *File = @ptrCast(@alignCast(ptr));
    if (file.tail == file.buffer.len) {
        flush(ptr);
        file.tail = 0;
    }
    file.buffer[file.tail] = byte;
    file.tail += 1;
}
pub fn main() !void {
    var buffer: [5]u8 = undefined;
    var stdout: File = .{ .handle = 1, .buffer = buffer[0..] };
    const writer: Writer = .{ .ptr = &stdout, .vtable = &.{ .flush = flush, .write_byte = write_byte } };
    writer.write_byte('H');
    writer.write_byte('e');
    writer.write_byte('l');
    writer.write_byte('l');
    writer.write_byte('o');
    writer.write_byte('w');
    writer.write_byte('o');
    writer.write_byte('r');
    writer.write_byte('l');
    writer.write_byte('d');
    writer.write_byte('\n');
    writer.write_byte('w');
    writer.write_byte('o');
    writer.write_byte('r');
    writer.write_byte('w');
    writer.write_byte('w');
    writer.write_byte('w');
    writer.write_byte('o');
    writer.write_byte('r');
    writer.write_byte('o');
    writer.write_byte('r');
    writer.write_byte('o');
    writer.write_byte('r');
    writer.flush();
}

zig source #3

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Source code

const std = @import("std");

const Writer = struct {
    ptr: *Base,
    vtable: *const struct { flush: *const fn (ptr: *Base) void },
    const Base = struct {
        buffer: []u8,
        tail: usize = 0,
    };
    pub fn write_byte(self: Writer, byte: u8) void {
        if (self.ptr.tail == self.ptr.buffer.len) {
            self.vtable.flush(self.ptr);
            self.ptr.tail = 0;
        }

self.ptr.buffer[self.ptr.tail] = byte;
        self.ptr.tail += 1;
    }
    pub fn flush(self: Writer) void {
        self.vtable.flush(self.ptr);
    }
};

const File = struct { handle: std.posix.fd_t, base: Writer.Base };
fn flush(ptr: *Writer.Base) void {
    const self: *File = @fieldParentPtr("base", ptr);
    _ = std.posix.write(self.handle, ptr.buffer[0..ptr.tail]) catch unreachable;
}
pub fn main() !void {
    var buffer: [5]u8 = undefined;
    var stdout: File = .{
        .handle = 1,
        .base = .{ .buffer = buffer[0..] },
    };
    const writer: Writer = .{ .ptr = &stdout.base, .vtable = &.{ .flush = flush } };
    writer.write_byte('H');
    writer.write_byte('e');
    writer.write_byte('l');
    writer.write_byte('l');
    writer.write_byte('o');
    writer.write_byte('w');
    writer.write_byte('o');
    writer.write_byte('r');
    writer.write_byte('l');
    writer.write_byte('d');
    writer.write_byte('\n');
    writer.write_byte('w');
    writer.write_byte('o');
    writer.write_byte('r');
    writer.write_byte('w');
    writer.write_byte('w');
    writer.write_byte('w');
    writer.write_byte('o');
    writer.write_byte('r');
    writer.write_byte('o');
    writer.write_byte('r');
    writer.write_byte('o');
    writer.write_byte('r');
    writer.flush();
}