Commit 7481582774

Jonathan Marler <johnnymarler@gmail.com>
2020-06-08 08:33:02
support Writer instead of OutStream
Start implementing https://github.com/ziglang/zig/issues/4917 which is to rename instream/outstream to reader/writer. This first change allows code to use Writer/writer instead of OutStream/outStream, but still maintains the old outstream names with "Deprecated" comments.
1 parent f5b584c
lib/std/fs/file.zig
@@ -648,9 +648,17 @@ pub const File = struct {
         return .{ .context = file };
     }
 
-    pub const OutStream = io.OutStream(File, WriteError, write);
+    pub const Writer = io.Writer(File, WriteError, write);
 
-    pub fn outStream(file: File) OutStream {
+    /// Deprecated: use `Writer`
+    pub const OutStream = Writer;
+
+    pub fn writer(file: File) Writer {
+        return .{ .context = file };
+    }
+
+    /// Deprecated: use `writer`
+    pub fn outStream(file: File) Writer {
         return .{ .context = file };
     }
 
lib/std/io/bit_out_stream.zig
@@ -1,197 +1,5 @@
-const std = @import("../std.zig");
-const builtin = std.builtin;
-const io = std.io;
-const testing = std.testing;
-const assert = std.debug.assert;
-const trait = std.meta.trait;
-const meta = std.meta;
-const math = std.math;
+/// Deprecated: use `std.io.bit_writer.BitWriter`
+pub const BitOutStream = @import("./bit_writer.zig").BitWriter;
 
-/// Creates a stream which allows for writing bit fields to another stream
-pub fn BitOutStream(endian: builtin.Endian, comptime OutStreamType: type) type {
-    return struct {
-        out_stream: OutStreamType,
-        bit_buffer: u8,
-        bit_count: u4,
-
-        pub const Error = OutStreamType.Error;
-        pub const OutStream = io.OutStream(*Self, Error, write);
-
-        const Self = @This();
-        const u8_bit_count = comptime meta.bitCount(u8);
-        const u4_bit_count = comptime meta.bitCount(u4);
-
-        pub fn init(out_stream: OutStreamType) Self {
-            return Self{
-                .out_stream = out_stream,
-                .bit_buffer = 0,
-                .bit_count = 0,
-            };
-        }
-
-        /// Write the specified number of bits to the stream from the least significant bits of
-        ///  the specified unsigned int value. Bits will only be written to the stream when there
-        ///  are enough to fill a byte.
-        pub fn writeBits(self: *Self, value: var, bits: usize) Error!void {
-            if (bits == 0) return;
-
-            const U = @TypeOf(value);
-            comptime assert(trait.isUnsignedInt(U));
-
-            //by extending the buffer to a minimum of u8 we can cover a number of edge cases
-            // related to shifting and casting.
-            const u_bit_count = comptime meta.bitCount(U);
-            const buf_bit_count = bc: {
-                assert(u_bit_count >= bits);
-                break :bc if (u_bit_count <= u8_bit_count) u8_bit_count else u_bit_count;
-            };
-            const Buf = std.meta.Int(false, buf_bit_count);
-            const BufShift = math.Log2Int(Buf);
-
-            const buf_value = @intCast(Buf, value);
-
-            const high_byte_shift = @intCast(BufShift, buf_bit_count - u8_bit_count);
-            var in_buffer = switch (endian) {
-                .Big => buf_value << @intCast(BufShift, buf_bit_count - bits),
-                .Little => buf_value,
-            };
-            var in_bits = bits;
-
-            if (self.bit_count > 0) {
-                const bits_remaining = u8_bit_count - self.bit_count;
-                const n = @intCast(u3, if (bits_remaining > bits) bits else bits_remaining);
-                switch (endian) {
-                    .Big => {
-                        const shift = @intCast(BufShift, high_byte_shift + self.bit_count);
-                        const v = @intCast(u8, in_buffer >> shift);
-                        self.bit_buffer |= v;
-                        in_buffer <<= n;
-                    },
-                    .Little => {
-                        const v = @truncate(u8, in_buffer) << @intCast(u3, self.bit_count);
-                        self.bit_buffer |= v;
-                        in_buffer >>= n;
-                    },
-                }
-                self.bit_count += n;
-                in_bits -= n;
-
-                //if we didn't fill the buffer, it's because bits < bits_remaining;
-                if (self.bit_count != u8_bit_count) return;
-                try self.out_stream.writeByte(self.bit_buffer);
-                self.bit_buffer = 0;
-                self.bit_count = 0;
-            }
-            //at this point we know bit_buffer is empty
-
-            //copy bytes until we can't fill one anymore, then leave the rest in bit_buffer
-            while (in_bits >= u8_bit_count) {
-                switch (endian) {
-                    .Big => {
-                        const v = @intCast(u8, in_buffer >> high_byte_shift);
-                        try self.out_stream.writeByte(v);
-                        in_buffer <<= @intCast(u3, u8_bit_count - 1);
-                        in_buffer <<= 1;
-                    },
-                    .Little => {
-                        const v = @truncate(u8, in_buffer);
-                        try self.out_stream.writeByte(v);
-                        in_buffer >>= @intCast(u3, u8_bit_count - 1);
-                        in_buffer >>= 1;
-                    },
-                }
-                in_bits -= u8_bit_count;
-            }
-
-            if (in_bits > 0) {
-                self.bit_count = @intCast(u4, in_bits);
-                self.bit_buffer = switch (endian) {
-                    .Big => @truncate(u8, in_buffer >> high_byte_shift),
-                    .Little => @truncate(u8, in_buffer),
-                };
-            }
-        }
-
-        /// Flush any remaining bits to the stream.
-        pub fn flushBits(self: *Self) Error!void {
-            if (self.bit_count == 0) return;
-            try self.out_stream.writeByte(self.bit_buffer);
-            self.bit_buffer = 0;
-            self.bit_count = 0;
-        }
-
-        pub fn write(self: *Self, buffer: []const u8) Error!usize {
-            // TODO: I'm not sure this is a good idea, maybe flushBits should be forced
-            if (self.bit_count > 0) {
-                for (buffer) |b, i|
-                    try self.writeBits(b, u8_bit_count);
-                return buffer.len;
-            }
-
-            return self.out_stream.write(buffer);
-        }
-
-        pub fn outStream(self: *Self) OutStream {
-            return .{ .context = self };
-        }
-    };
-}
-
-pub fn bitOutStream(
-    comptime endian: builtin.Endian,
-    underlying_stream: var,
-) BitOutStream(endian, @TypeOf(underlying_stream)) {
-    return BitOutStream(endian, @TypeOf(underlying_stream)).init(underlying_stream);
-}
-
-test "api coverage" {
-    var mem_be = [_]u8{0} ** 2;
-    var mem_le = [_]u8{0} ** 2;
-
-    var mem_out_be = io.fixedBufferStream(&mem_be);
-    var bit_stream_be = bitOutStream(.Big, mem_out_be.outStream());
-
-    try bit_stream_be.writeBits(@as(u2, 1), 1);
-    try bit_stream_be.writeBits(@as(u5, 2), 2);
-    try bit_stream_be.writeBits(@as(u128, 3), 3);
-    try bit_stream_be.writeBits(@as(u8, 4), 4);
-    try bit_stream_be.writeBits(@as(u9, 5), 5);
-    try bit_stream_be.writeBits(@as(u1, 1), 1);
-
-    testing.expect(mem_be[0] == 0b11001101 and mem_be[1] == 0b00001011);
-
-    mem_out_be.pos = 0;
-
-    try bit_stream_be.writeBits(@as(u15, 0b110011010000101), 15);
-    try bit_stream_be.flushBits();
-    testing.expect(mem_be[0] == 0b11001101 and mem_be[1] == 0b00001010);
-
-    mem_out_be.pos = 0;
-    try bit_stream_be.writeBits(@as(u32, 0b110011010000101), 16);
-    testing.expect(mem_be[0] == 0b01100110 and mem_be[1] == 0b10000101);
-
-    try bit_stream_be.writeBits(@as(u0, 0), 0);
-
-    var mem_out_le = io.fixedBufferStream(&mem_le);
-    var bit_stream_le = bitOutStream(.Little, mem_out_le.outStream());
-
-    try bit_stream_le.writeBits(@as(u2, 1), 1);
-    try bit_stream_le.writeBits(@as(u5, 2), 2);
-    try bit_stream_le.writeBits(@as(u128, 3), 3);
-    try bit_stream_le.writeBits(@as(u8, 4), 4);
-    try bit_stream_le.writeBits(@as(u9, 5), 5);
-    try bit_stream_le.writeBits(@as(u1, 1), 1);
-
-    testing.expect(mem_le[0] == 0b00011101 and mem_le[1] == 0b10010101);
-
-    mem_out_le.pos = 0;
-    try bit_stream_le.writeBits(@as(u15, 0b110011010000101), 15);
-    try bit_stream_le.flushBits();
-    testing.expect(mem_le[0] == 0b10000101 and mem_le[1] == 0b01100110);
-
-    mem_out_le.pos = 0;
-    try bit_stream_le.writeBits(@as(u32, 0b1100110100001011), 16);
-    testing.expect(mem_le[0] == 0b00001011 and mem_le[1] == 0b11001101);
-
-    try bit_stream_le.writeBits(@as(u0, 0), 0);
-}
+/// Deprecated: use `std.io.bit_writer.bitWriter`
+pub const bitOutStream = @import("./bit_writer.zig").bitWriter;
lib/std/io/bit_writer.zig
@@ -0,0 +1,203 @@
+const std = @import("../std.zig");
+const builtin = std.builtin;
+const io = std.io;
+const testing = std.testing;
+const assert = std.debug.assert;
+const trait = std.meta.trait;
+const meta = std.meta;
+const math = std.math;
+
+/// Creates a stream which allows for writing bit fields to another stream
+pub fn BitWriter(endian: builtin.Endian, comptime WriterType: type) type {
+    return struct {
+        forward_writer: WriterType,
+        bit_buffer: u8,
+        bit_count: u4,
+
+        pub const Error = WriterType.Error;
+        pub const Writer = io.Writer(*Self, Error, write);
+        /// Deprecated: use `Writer`
+        pub const OutStream = io.OutStream(*Self, Error, write);
+
+        const Self = @This();
+        const u8_bit_count = comptime meta.bitCount(u8);
+        const u4_bit_count = comptime meta.bitCount(u4);
+
+        pub fn init(forward_writer: WriterType) Self {
+            return Self{
+                .forward_writer = forward_writer,
+                .bit_buffer = 0,
+                .bit_count = 0,
+            };
+        }
+
+        /// Write the specified number of bits to the stream from the least significant bits of
+        ///  the specified unsigned int value. Bits will only be written to the stream when there
+        ///  are enough to fill a byte.
+        pub fn writeBits(self: *Self, value: var, bits: usize) Error!void {
+            if (bits == 0) return;
+
+            const U = @TypeOf(value);
+            comptime assert(trait.isUnsignedInt(U));
+
+            //by extending the buffer to a minimum of u8 we can cover a number of edge cases
+            // related to shifting and casting.
+            const u_bit_count = comptime meta.bitCount(U);
+            const buf_bit_count = bc: {
+                assert(u_bit_count >= bits);
+                break :bc if (u_bit_count <= u8_bit_count) u8_bit_count else u_bit_count;
+            };
+            const Buf = std.meta.Int(false, buf_bit_count);
+            const BufShift = math.Log2Int(Buf);
+
+            const buf_value = @intCast(Buf, value);
+
+            const high_byte_shift = @intCast(BufShift, buf_bit_count - u8_bit_count);
+            var in_buffer = switch (endian) {
+                .Big => buf_value << @intCast(BufShift, buf_bit_count - bits),
+                .Little => buf_value,
+            };
+            var in_bits = bits;
+
+            if (self.bit_count > 0) {
+                const bits_remaining = u8_bit_count - self.bit_count;
+                const n = @intCast(u3, if (bits_remaining > bits) bits else bits_remaining);
+                switch (endian) {
+                    .Big => {
+                        const shift = @intCast(BufShift, high_byte_shift + self.bit_count);
+                        const v = @intCast(u8, in_buffer >> shift);
+                        self.bit_buffer |= v;
+                        in_buffer <<= n;
+                    },
+                    .Little => {
+                        const v = @truncate(u8, in_buffer) << @intCast(u3, self.bit_count);
+                        self.bit_buffer |= v;
+                        in_buffer >>= n;
+                    },
+                }
+                self.bit_count += n;
+                in_bits -= n;
+
+                //if we didn't fill the buffer, it's because bits < bits_remaining;
+                if (self.bit_count != u8_bit_count) return;
+                try self.forward_writer.writeByte(self.bit_buffer);
+                self.bit_buffer = 0;
+                self.bit_count = 0;
+            }
+            //at this point we know bit_buffer is empty
+
+            //copy bytes until we can't fill one anymore, then leave the rest in bit_buffer
+            while (in_bits >= u8_bit_count) {
+                switch (endian) {
+                    .Big => {
+                        const v = @intCast(u8, in_buffer >> high_byte_shift);
+                        try self.forward_writer.writeByte(v);
+                        in_buffer <<= @intCast(u3, u8_bit_count - 1);
+                        in_buffer <<= 1;
+                    },
+                    .Little => {
+                        const v = @truncate(u8, in_buffer);
+                        try self.forward_writer.writeByte(v);
+                        in_buffer >>= @intCast(u3, u8_bit_count - 1);
+                        in_buffer >>= 1;
+                    },
+                }
+                in_bits -= u8_bit_count;
+            }
+
+            if (in_bits > 0) {
+                self.bit_count = @intCast(u4, in_bits);
+                self.bit_buffer = switch (endian) {
+                    .Big => @truncate(u8, in_buffer >> high_byte_shift),
+                    .Little => @truncate(u8, in_buffer),
+                };
+            }
+        }
+
+        /// Flush any remaining bits to the stream.
+        pub fn flushBits(self: *Self) Error!void {
+            if (self.bit_count == 0) return;
+            try self.forward_writer.writeByte(self.bit_buffer);
+            self.bit_buffer = 0;
+            self.bit_count = 0;
+        }
+
+        pub fn write(self: *Self, buffer: []const u8) Error!usize {
+            // TODO: I'm not sure this is a good idea, maybe flushBits should be forced
+            if (self.bit_count > 0) {
+                for (buffer) |b, i|
+                    try self.writeBits(b, u8_bit_count);
+                return buffer.len;
+            }
+
+            return self.forward_writer.write(buffer);
+        }
+
+        pub fn writer(self: *Self) Writer {
+            return .{ .context = self };
+        }
+        /// Deprecated: use `writer`
+        pub fn outStream(self: *Self) OutStream {
+            return .{ .context = self };
+        }
+    };
+}
+
+pub fn bitWriter(
+    comptime endian: builtin.Endian,
+    underlying_stream: var,
+) BitWriter(endian, @TypeOf(underlying_stream)) {
+    return BitWriter(endian, @TypeOf(underlying_stream)).init(underlying_stream);
+}
+
+test "api coverage" {
+    var mem_be = [_]u8{0} ** 2;
+    var mem_le = [_]u8{0} ** 2;
+
+    var mem_out_be = io.fixedBufferStream(&mem_be);
+    var bit_stream_be = bitWriter(.Big, mem_out_be.writer());
+
+    try bit_stream_be.writeBits(@as(u2, 1), 1);
+    try bit_stream_be.writeBits(@as(u5, 2), 2);
+    try bit_stream_be.writeBits(@as(u128, 3), 3);
+    try bit_stream_be.writeBits(@as(u8, 4), 4);
+    try bit_stream_be.writeBits(@as(u9, 5), 5);
+    try bit_stream_be.writeBits(@as(u1, 1), 1);
+
+    testing.expect(mem_be[0] == 0b11001101 and mem_be[1] == 0b00001011);
+
+    mem_out_be.pos = 0;
+
+    try bit_stream_be.writeBits(@as(u15, 0b110011010000101), 15);
+    try bit_stream_be.flushBits();
+    testing.expect(mem_be[0] == 0b11001101 and mem_be[1] == 0b00001010);
+
+    mem_out_be.pos = 0;
+    try bit_stream_be.writeBits(@as(u32, 0b110011010000101), 16);
+    testing.expect(mem_be[0] == 0b01100110 and mem_be[1] == 0b10000101);
+
+    try bit_stream_be.writeBits(@as(u0, 0), 0);
+
+    var mem_out_le = io.fixedBufferStream(&mem_le);
+    var bit_stream_le = bitWriter(.Little, mem_out_le.writer());
+
+    try bit_stream_le.writeBits(@as(u2, 1), 1);
+    try bit_stream_le.writeBits(@as(u5, 2), 2);
+    try bit_stream_le.writeBits(@as(u128, 3), 3);
+    try bit_stream_le.writeBits(@as(u8, 4), 4);
+    try bit_stream_le.writeBits(@as(u9, 5), 5);
+    try bit_stream_le.writeBits(@as(u1, 1), 1);
+
+    testing.expect(mem_le[0] == 0b00011101 and mem_le[1] == 0b10010101);
+
+    mem_out_le.pos = 0;
+    try bit_stream_le.writeBits(@as(u15, 0b110011010000101), 15);
+    try bit_stream_le.flushBits();
+    testing.expect(mem_le[0] == 0b10000101 and mem_le[1] == 0b01100110);
+
+    mem_out_le.pos = 0;
+    try bit_stream_le.writeBits(@as(u32, 0b1100110100001011), 16);
+    testing.expect(mem_le[0] == 0b00001011 and mem_le[1] == 0b11001101);
+
+    try bit_stream_le.writeBits(@as(u0, 0), 0);
+}
lib/std/io/buffered_atomic_file.zig
@@ -34,7 +34,7 @@ pub const BufferedAtomicFile = struct {
         errdefer self.atomic_file.deinit();
 
         self.file_stream = self.atomic_file.file.outStream();
-        self.buffered_stream = .{ .unbuffered_out_stream = self.file_stream };
+        self.buffered_stream = .{ .unbuffered_writer = self.file_stream };
         return self;
     }
 
lib/std/io/buffered_out_stream.zig
@@ -1,41 +1,5 @@
-const std = @import("../std.zig");
-const io = std.io;
+/// Deprecated: use `std.io.buffered_writer.BufferedWriter`
+pub const BufferedOutStream = @import("./buffered_writer.zig").BufferedWriter;
 
-pub fn BufferedOutStream(comptime buffer_size: usize, comptime OutStreamType: type) type {
-    return struct {
-        unbuffered_out_stream: OutStreamType,
-        fifo: FifoType = FifoType.init(),
-
-        pub const Error = OutStreamType.Error;
-        pub const OutStream = io.OutStream(*Self, Error, write);
-
-        const Self = @This();
-        const FifoType = std.fifo.LinearFifo(u8, std.fifo.LinearFifoBufferType{ .Static = buffer_size });
-
-        pub fn flush(self: *Self) !void {
-            while (true) {
-                const slice = self.fifo.readableSlice(0);
-                if (slice.len == 0) break;
-                try self.unbuffered_out_stream.writeAll(slice);
-                self.fifo.discard(slice.len);
-            }
-        }
-
-        pub fn outStream(self: *Self) OutStream {
-            return .{ .context = self };
-        }
-
-        pub fn write(self: *Self, bytes: []const u8) Error!usize {
-            if (bytes.len >= self.fifo.writableLength()) {
-                try self.flush();
-                return self.unbuffered_out_stream.write(bytes);
-            }
-            self.fifo.writeAssumeCapacity(bytes);
-            return bytes.len;
-        }
-    };
-}
-
-pub fn bufferedOutStream(underlying_stream: var) BufferedOutStream(4096, @TypeOf(underlying_stream)) {
-    return .{ .unbuffered_out_stream = underlying_stream };
-}
+/// Deprecated: use `std.io.buffered_writer.bufferedWriter`
+pub const bufferedOutStream = @import("./buffered_writer.zig").bufferedWriter
lib/std/io/buffered_writer.zig
@@ -0,0 +1,48 @@
+const std = @import("../std.zig");
+const io = std.io;
+
+pub fn BufferedWriter(comptime buffer_size: usize, comptime WriterType: type) type {
+    return struct {
+        unbuffered_writer: WriterType,
+        fifo: FifoType = FifoType.init(),
+
+        pub const Error = WriterType.Error;
+        pub const Writer = io.Writer(*Self, Error, write);
+        /// Deprecated: use `Writer`
+        pub const OutStream = Writer;
+
+        const Self = @This();
+        const FifoType = std.fifo.LinearFifo(u8, std.fifo.LinearFifoBufferType{ .Static = buffer_size });
+
+        pub fn flush(self: *Self) !void {
+            while (true) {
+                const slice = self.fifo.readableSlice(0);
+                if (slice.len == 0) break;
+                try self.unbuffered_writer.writeAll(slice);
+                self.fifo.discard(slice.len);
+            }
+        }
+
+        pub fn writer(self: *Self) Writer {
+            return .{ .context = self };
+        }
+
+        /// Deprecated: use writer
+        pub fn outStream(self: *Self) Writer {
+            return .{ .context = self };
+        }
+
+        pub fn write(self: *Self, bytes: []const u8) Error!usize {
+            if (bytes.len >= self.fifo.writableLength()) {
+                try self.flush();
+                return self.unbuffered_writer.write(bytes);
+            }
+            self.fifo.writeAssumeCapacity(bytes);
+            return bytes.len;
+        }
+    };
+}
+
+pub fn bufferedWriter(underlying_stream: var) BufferedWriter(4096, @TypeOf(underlying_stream)) {
+    return .{ .unbuffered_writer = underlying_stream };
+}
lib/std/io/c_out_stream.zig
@@ -1,44 +1,5 @@
-const std = @import("../std.zig");
-const builtin = std.builtin;
-const io = std.io;
-const testing = std.testing;
+/// Deprecated: use `std.io.c_writer.CWriter`
+pub const COutStream = @import("./c_writer.zig").CWriter;
 
-pub const COutStream = io.OutStream(*std.c.FILE, std.fs.File.WriteError, cOutStreamWrite);
-
-pub fn cOutStream(c_file: *std.c.FILE) COutStream {
-    return .{ .context = c_file };
-}
-
-fn cOutStreamWrite(c_file: *std.c.FILE, bytes: []const u8) std.fs.File.WriteError!usize {
-    const amt_written = std.c.fwrite(bytes.ptr, 1, bytes.len, c_file);
-    if (amt_written >= 0) return amt_written;
-    switch (std.c._errno().*) {
-        0 => unreachable,
-        os.EINVAL => unreachable,
-        os.EFAULT => unreachable,
-        os.EAGAIN => unreachable, // this is a blocking API
-        os.EBADF => unreachable, // always a race condition
-        os.EDESTADDRREQ => unreachable, // connect was never called
-        os.EDQUOT => return error.DiskQuota,
-        os.EFBIG => return error.FileTooBig,
-        os.EIO => return error.InputOutput,
-        os.ENOSPC => return error.NoSpaceLeft,
-        os.EPERM => return error.AccessDenied,
-        os.EPIPE => return error.BrokenPipe,
-        else => |err| return os.unexpectedErrno(@intCast(usize, err)),
-    }
-}
-
-test "" {
-    if (!builtin.link_libc) return error.SkipZigTest;
-
-    const filename = "tmp_io_test_file.txt";
-    const out_file = std.c.fopen(filename, "w") orelse return error.UnableToOpenTestFile;
-    defer {
-        _ = std.c.fclose(out_file);
-        std.fs.cwd().deleteFileZ(filename) catch {};
-    }
-
-    const out_stream = cOutStream(out_file);
-    try out_stream.print("hi: {}\n", .{@as(i32, 123)});
-}
+/// Deprecated: use `std.io.c_writer.cWriter`
+pub const cOutStream = @import("./c_writer.zig").cWriter;
lib/std/io/c_writer.zig
@@ -0,0 +1,44 @@
+const std = @import("../std.zig");
+const builtin = std.builtin;
+const io = std.io;
+const testing = std.testing;
+
+pub const CWriter = io.Writer(*std.c.FILE, std.fs.File.WriteError, cWriterWrite);
+
+pub fn cWriter(c_file: *std.c.FILE) CWriter {
+    return .{ .context = c_file };
+}
+
+fn cWriterWrite(c_file: *std.c.FILE, bytes: []const u8) std.fs.File.WriteError!usize {
+    const amt_written = std.c.fwrite(bytes.ptr, 1, bytes.len, c_file);
+    if (amt_written >= 0) return amt_written;
+    switch (std.c._errno().*) {
+        0 => unreachable,
+        os.EINVAL => unreachable,
+        os.EFAULT => unreachable,
+        os.EAGAIN => unreachable, // this is a blocking API
+        os.EBADF => unreachable, // always a race condition
+        os.EDESTADDRREQ => unreachable, // connect was never called
+        os.EDQUOT => return error.DiskQuota,
+        os.EFBIG => return error.FileTooBig,
+        os.EIO => return error.InputOutput,
+        os.ENOSPC => return error.NoSpaceLeft,
+        os.EPERM => return error.AccessDenied,
+        os.EPIPE => return error.BrokenPipe,
+        else => |err| return os.unexpectedErrno(@intCast(usize, err)),
+    }
+}
+
+test "" {
+    if (!builtin.link_libc) return error.SkipZigTest;
+
+    const filename = "tmp_io_test_file.txt";
+    const out_file = std.c.fopen(filename, "w") orelse return error.UnableToOpenTestFile;
+    defer {
+        _ = std.c.fclose(out_file);
+        std.fs.cwd().deleteFileZ(filename) catch {};
+    }
+
+    const writer = cWriter(out_file);
+    try writer.print("hi: {}\n", .{@as(i32, 123)});
+}
lib/std/io/counting_out_stream.zig
@@ -1,39 +1,5 @@
-const std = @import("../std.zig");
-const io = std.io;
-const testing = std.testing;
+/// Deprecated: use `std.io.counting_writer.CountingWriter`
+pub const CountingOutStream = @import("./counting_writer.zig").CountingWriter;
 
-/// An OutStream that counts how many bytes has been written to it.
-pub fn CountingOutStream(comptime OutStreamType: type) type {
-    return struct {
-        bytes_written: u64,
-        child_stream: OutStreamType,
-
-        pub const Error = OutStreamType.Error;
-        pub const OutStream = io.OutStream(*Self, Error, write);
-
-        const Self = @This();
-
-        pub fn write(self: *Self, bytes: []const u8) Error!usize {
-            const amt = try self.child_stream.write(bytes);
-            self.bytes_written += amt;
-            return amt;
-        }
-
-        pub fn outStream(self: *Self) OutStream {
-            return .{ .context = self };
-        }
-    };
-}
-
-pub fn countingOutStream(child_stream: var) CountingOutStream(@TypeOf(child_stream)) {
-    return .{ .bytes_written = 0, .child_stream = child_stream };
-}
-
-test "io.CountingOutStream" {
-    var counting_stream = countingOutStream(std.io.null_out_stream);
-    const stream = counting_stream.outStream();
-
-    const bytes = "yay" ** 100;
-    stream.writeAll(bytes) catch unreachable;
-    testing.expect(counting_stream.bytes_written == bytes.len);
-}
+/// Deprecated: use `std.io.counting_writer.countingWriter`
+pub const countingOutStream = @import("./counting_writer.zig").countingWriter;
lib/std/io/counting_writer.zig
@@ -0,0 +1,46 @@
+const std = @import("../std.zig");
+const io = std.io;
+const testing = std.testing;
+
+/// A Writer that counts how many bytes has been written to it.
+pub fn CountingWriter(comptime WriterType: type) type {
+    return struct {
+        bytes_written: u64,
+        child_stream: WriterType,
+
+        pub const Error = WriterType.Error;
+        pub const Writer = io.Writer(*Self, Error, write);
+        /// Deprecated: use `Writer`
+        pub const OutStream = Writer;
+
+        const Self = @This();
+
+        pub fn write(self: *Self, bytes: []const u8) Error!usize {
+            const amt = try self.child_stream.write(bytes);
+            self.bytes_written += amt;
+            return amt;
+        }
+
+        pub fn writer(self: *Self) Writer {
+            return .{ .context = self };
+        }
+
+        /// Deprecated: use `writer`
+        pub fn outStream(self: *Self) OutStream {
+            return .{ .context = self };
+        }
+    };
+}
+
+pub fn countingWriter(child_stream: var) CountingWriter(@TypeOf(child_stream)) {
+    return .{ .bytes_written = 0, .child_stream = child_stream };
+}
+
+test "io.CountingWriter" {
+    var counting_stream = countingWriter(std.io.null_writer);
+    const stream = counting_stream.writer();
+
+    const bytes = "yay" ** 100;
+    stream.writeAll(bytes) catch unreachable;
+    testing.expect(counting_stream.bytes_written == bytes.len);
+}
lib/std/io/fixed_buffer_stream.zig
@@ -18,7 +18,9 @@ pub fn FixedBufferStream(comptime Buffer: type) type {
         pub const GetSeekPosError = error{};
 
         pub const InStream = io.InStream(*Self, ReadError, read);
-        pub const OutStream = io.OutStream(*Self, WriteError, write);
+        pub const Writer = io.Writer(*Self, WriteError, write);
+        /// Deprecated: use `Writer`
+        pub const OutStream = Writer;
 
         pub const SeekableStream = io.SeekableStream(
             *Self,
@@ -36,6 +38,11 @@ pub fn FixedBufferStream(comptime Buffer: type) type {
             return .{ .context = self };
         }
 
+        pub fn writer(self: *Self) Writer {
+            return .{ .context = self };
+        }
+
+        /// Deprecated: use `writer`
         pub fn outStream(self: *Self) OutStream {
             return .{ .context = self };
         }
@@ -126,7 +133,7 @@ fn NonSentinelSpan(comptime T: type) type {
 test "FixedBufferStream output" {
     var buf: [255]u8 = undefined;
     var fbs = fixedBufferStream(&buf);
-    const stream = fbs.outStream();
+    const stream = fbs.writer();
 
     try stream.print("{}{}!", .{ "Hello", "World" });
     testing.expectEqualSlices(u8, "HelloWorld!", fbs.getWritten());
@@ -136,19 +143,19 @@ test "FixedBufferStream output 2" {
     var buffer: [10]u8 = undefined;
     var fbs = fixedBufferStream(&buffer);
 
-    try fbs.outStream().writeAll("Hello");
+    try fbs.writer().writeAll("Hello");
     testing.expect(mem.eql(u8, fbs.getWritten(), "Hello"));
 
-    try fbs.outStream().writeAll("world");
+    try fbs.writer().writeAll("world");
     testing.expect(mem.eql(u8, fbs.getWritten(), "Helloworld"));
 
-    testing.expectError(error.NoSpaceLeft, fbs.outStream().writeAll("!"));
+    testing.expectError(error.NoSpaceLeft, fbs.writer().writeAll("!"));
     testing.expect(mem.eql(u8, fbs.getWritten(), "Helloworld"));
 
     fbs.reset();
     testing.expect(fbs.getWritten().len == 0);
 
-    testing.expectError(error.NoSpaceLeft, fbs.outStream().writeAll("Hello world!"));
+    testing.expectError(error.NoSpaceLeft, fbs.writer().writeAll("Hello world!"));
     testing.expect(mem.eql(u8, fbs.getWritten(), "Hello worl"));
 }
 
lib/std/io/multi_out_stream.zig
@@ -1,51 +1,5 @@
-const std = @import("../std.zig");
-const io = std.io;
-const testing = std.testing;
+/// Deprecated: use `std.io.multi_writer.MultiWriter`
+pub const MultiOutStream = @import("./multi_writer.zig").MultiWriter;
 
-/// Takes a tuple of streams, and constructs a new stream that writes to all of them
-pub fn MultiOutStream(comptime OutStreams: type) type {
-    comptime var ErrSet = error{};
-    inline for (@typeInfo(OutStreams).Struct.fields) |field| {
-        const StreamType = field.field_type;
-        ErrSet = ErrSet || StreamType.Error;
-    }
-
-    return struct {
-        const Self = @This();
-
-        streams: OutStreams,
-
-        pub const Error = ErrSet;
-        pub const OutStream = io.OutStream(*Self, Error, write);
-        pub fn outStream(self: *Self) OutStream {
-            return .{ .context = self };
-        }
-
-        pub fn write(self: *Self, bytes: []const u8) Error!usize {
-            var batch = std.event.Batch(Error!void, self.streams.len, .auto_async).init();
-            comptime var i = 0;
-            inline while (i < self.streams.len) : (i += 1) {
-                const stream = self.streams[i];
-                // TODO: remove ptrCast: https://github.com/ziglang/zig/issues/5258
-                batch.add(@ptrCast(anyframe->Error!void, &async stream.writeAll(bytes)));
-            }
-            try batch.wait();
-            return bytes.len;
-        }
-    };
-}
-
-pub fn multiOutStream(streams: var) MultiOutStream(@TypeOf(streams)) {
-    return .{ .streams = streams };
-}
-
-test "MultiOutStream" {
-    var buf1: [255]u8 = undefined;
-    var fbs1 = io.fixedBufferStream(&buf1);
-    var buf2: [255]u8 = undefined;
-    var fbs2 = io.fixedBufferStream(&buf2);
-    var stream = multiOutStream(.{ fbs1.outStream(), fbs2.outStream() });
-    try stream.outStream().print("HI", .{});
-    testing.expectEqualSlices(u8, "HI", fbs1.getWritten());
-    testing.expectEqualSlices(u8, "HI", fbs2.getWritten());
-}
+/// Deprecated: use `std.io.multi_writer.multiWriter`
+pub const multiOutStream = @import("./multi_writer.zig").multiWriter;
lib/std/io/multi_writer.zig
@@ -0,0 +1,59 @@
+const std = @import("../std.zig");
+const io = std.io;
+const testing = std.testing;
+
+/// Takes a tuple of streams, and constructs a new stream that writes to all of them
+pub fn MultiWriter(comptime Writers: type) type {
+    comptime var ErrSet = error{};
+    inline for (@typeInfo(Writers).Struct.fields) |field| {
+        const StreamType = field.field_type;
+        ErrSet = ErrSet || StreamType.Error;
+    }
+
+    return struct {
+        const Self = @This();
+
+        streams: Writers,
+
+        pub const Error = ErrSet;
+        pub const Writer = io.Writer(*Self, Error, write);
+        /// Deprecated: use `Writer`
+        pub const OutStream = Writer;
+
+        pub fn writer(self: *Self) Writer {
+            return .{ .context = self };
+        }
+
+        /// Deprecated: use `writer`
+        pub fn outStream(self: *Self) OutStream {
+            return .{ .context = self };
+        }
+
+        pub fn write(self: *Self, bytes: []const u8) Error!usize {
+            var batch = std.event.Batch(Error!void, self.streams.len, .auto_async).init();
+            comptime var i = 0;
+            inline while (i < self.streams.len) : (i += 1) {
+                const stream = self.streams[i];
+                // TODO: remove ptrCast: https://github.com/ziglang/zig/issues/5258
+                batch.add(@ptrCast(anyframe->Error!void, &async stream.writeAll(bytes)));
+            }
+            try batch.wait();
+            return bytes.len;
+        }
+    };
+}
+
+pub fn multiWriter(streams: var) MultiWriter(@TypeOf(streams)) {
+    return .{ .streams = streams };
+}
+
+test "MultiWriter" {
+    var buf1: [255]u8 = undefined;
+    var fbs1 = io.fixedBufferStream(&buf1);
+    var buf2: [255]u8 = undefined;
+    var fbs2 = io.fixedBufferStream(&buf2);
+    var stream = multiWriter(.{ fbs1.writer(), fbs2.writer() });
+    try stream.writer().print("HI", .{});
+    testing.expectEqualSlices(u8, "HI", fbs1.getWritten());
+    testing.expectEqualSlices(u8, "HI", fbs2.getWritten());
+}
lib/std/io/out_stream.zig
@@ -1,85 +1,2 @@
-const std = @import("../std.zig");
-const builtin = std.builtin;
-const mem = std.mem;
-
-pub fn OutStream(
-    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: var) 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;
-            mem.set(u8, bytes[0..], byte);
-
-            var remaining: usize = n;
-            while (remaining > 0) {
-                const to_write = std.math.min(remaining, bytes.len);
-                try self.writeAll(bytes[0..to_write]);
-                remaining -= to_write;
-            }
-        }
-
-        /// Write a native-endian integer.
-        /// TODO audit non-power-of-two int sizes
-        pub fn writeIntNative(self: Self, comptime T: type, value: T) Error!void {
-            var bytes: [(T.bit_count + 7) / 8]u8 = undefined;
-            mem.writeIntNative(T, &bytes, value);
-            return self.writeAll(&bytes);
-        }
-
-        /// Write a foreign-endian integer.
-        /// TODO audit non-power-of-two int sizes
-        pub fn writeIntForeign(self: Self, comptime T: type, value: T) Error!void {
-            var bytes: [(T.bit_count + 7) / 8]u8 = undefined;
-            mem.writeIntForeign(T, &bytes, value);
-            return self.writeAll(&bytes);
-        }
-
-        /// TODO audit non-power-of-two int sizes
-        pub fn writeIntLittle(self: Self, comptime T: type, value: T) Error!void {
-            var bytes: [(T.bit_count + 7) / 8]u8 = undefined;
-            mem.writeIntLittle(T, &bytes, value);
-            return self.writeAll(&bytes);
-        }
-
-        /// TODO audit non-power-of-two int sizes
-        pub fn writeIntBig(self: Self, comptime T: type, value: T) Error!void {
-            var bytes: [(T.bit_count + 7) / 8]u8 = undefined;
-            mem.writeIntBig(T, &bytes, value);
-            return self.writeAll(&bytes);
-        }
-
-        /// TODO audit non-power-of-two int sizes
-        pub fn writeInt(self: Self, comptime T: type, value: T, endian: builtin.Endian) Error!void {
-            var bytes: [(T.bit_count + 7) / 8]u8 = undefined;
-            mem.writeInt(T, &bytes, value, endian);
-            return self.writeAll(&bytes);
-        }
-    };
-}
+/// Deprecated: use `std.io.writer.Writer`
+pub const OutStream = @import("./writer.zig").Writer;
lib/std/io/writer.zig
@@ -0,0 +1,85 @@
+const std = @import("../std.zig");
+const builtin = std.builtin;
+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: var) 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;
+            mem.set(u8, bytes[0..], byte);
+
+            var remaining: usize = n;
+            while (remaining > 0) {
+                const to_write = std.math.min(remaining, bytes.len);
+                try self.writeAll(bytes[0..to_write]);
+                remaining -= to_write;
+            }
+        }
+
+        /// Write a native-endian integer.
+        /// TODO audit non-power-of-two int sizes
+        pub fn writeIntNative(self: Self, comptime T: type, value: T) Error!void {
+            var bytes: [(T.bit_count + 7) / 8]u8 = undefined;
+            mem.writeIntNative(T, &bytes, value);
+            return self.writeAll(&bytes);
+        }
+
+        /// Write a foreign-endian integer.
+        /// TODO audit non-power-of-two int sizes
+        pub fn writeIntForeign(self: Self, comptime T: type, value: T) Error!void {
+            var bytes: [(T.bit_count + 7) / 8]u8 = undefined;
+            mem.writeIntForeign(T, &bytes, value);
+            return self.writeAll(&bytes);
+        }
+
+        /// TODO audit non-power-of-two int sizes
+        pub fn writeIntLittle(self: Self, comptime T: type, value: T) Error!void {
+            var bytes: [(T.bit_count + 7) / 8]u8 = undefined;
+            mem.writeIntLittle(T, &bytes, value);
+            return self.writeAll(&bytes);
+        }
+
+        /// TODO audit non-power-of-two int sizes
+        pub fn writeIntBig(self: Self, comptime T: type, value: T) Error!void {
+            var bytes: [(T.bit_count + 7) / 8]u8 = undefined;
+            mem.writeIntBig(T, &bytes, value);
+            return self.writeAll(&bytes);
+        }
+
+        /// TODO audit non-power-of-two int sizes
+        pub fn writeInt(self: Self, comptime T: type, value: T, endian: builtin.Endian) Error!void {
+            var bytes: [(T.bit_count + 7) / 8]u8 = undefined;
+            mem.writeInt(T, &bytes, value, endian);
+            return self.writeAll(&bytes);
+        }
+    };
+}
lib/std/zig/render.zig
@@ -49,7 +49,7 @@ pub fn render(allocator: *mem.Allocator, stream: var, tree: *ast.Tree) (@TypeOf(
         .source_index = 0,
         .source = tree.source,
     };
-    const my_stream_stream: std.io.OutStream(*MyStream, MyStream.StreamError, MyStream.write) = .{
+    const my_stream_stream: std.io.Writer(*MyStream, MyStream.StreamError, MyStream.write) = .{
         .context = &my_stream,
     };
 
lib/std/debug.zig
@@ -53,7 +53,7 @@ pub const LineInfo = struct {
 /// Tries to write to stderr, unbuffered, and ignores any error returned.
 /// Does not append a newline.
 var stderr_file: File = undefined;
-var stderr_file_out_stream: File.OutStream = undefined;
+var stderr_file_writer: File.Writer = undefined;
 
 var stderr_stream: ?*File.OutStream = null;
 var stderr_mutex = std.Mutex.init();
@@ -70,8 +70,8 @@ pub fn getStderrStream() *File.OutStream {
         return st;
     } else {
         stderr_file = io.getStdErr();
-        stderr_file_out_stream = stderr_file.outStream();
-        const st = &stderr_file_out_stream;
+        stderr_file_writer = stderr_file.outStream();
+        const st = &stderr_file_writer;
         stderr_stream = st;
         return st;
     }
lib/std/io.zig
@@ -102,11 +102,17 @@ pub fn getStdIn() File {
 }
 
 pub const InStream = @import("io/in_stream.zig").InStream;
-pub const OutStream = @import("io/out_stream.zig").OutStream;
+pub const Writer = @import("io/writer.zig").Writer;
+/// Deprecated: use `Writer`
+pub const OutStream = Writer;
 pub const SeekableStream = @import("io/seekable_stream.zig").SeekableStream;
 
-pub const BufferedOutStream = @import("io/buffered_out_stream.zig").BufferedOutStream;
-pub const bufferedOutStream = @import("io/buffered_out_stream.zig").bufferedOutStream;
+pub const BufferedWriter = @import("io/buffered_writer.zig").BufferedWriter;
+pub const bufferedWriter = @import("io/buffered_writer.zig").bufferedWriter;
+/// Deprecated: use `BufferedWriter`
+pub const BufferedOutStream = BufferedWriter;
+/// Deprecated: use `bufferedWriter`
+pub const bufferedOutStream = bufferedWriter;
 
 pub const BufferedInStream = @import("io/buffered_in_stream.zig").BufferedInStream;
 pub const bufferedInStream = @import("io/buffered_in_stream.zig").bufferedInStream;
@@ -117,20 +123,36 @@ pub const peekStream = @import("io/peek_stream.zig").peekStream;
 pub const FixedBufferStream = @import("io/fixed_buffer_stream.zig").FixedBufferStream;
 pub const fixedBufferStream = @import("io/fixed_buffer_stream.zig").fixedBufferStream;
 
-pub const COutStream = @import("io/c_out_stream.zig").COutStream;
-pub const cOutStream = @import("io/c_out_stream.zig").cOutStream;
-
-pub const CountingOutStream = @import("io/counting_out_stream.zig").CountingOutStream;
-pub const countingOutStream = @import("io/counting_out_stream.zig").countingOutStream;
-
-pub const MultiOutStream = @import("io/multi_out_stream.zig").MultiOutStream;
-pub const multiOutStream = @import("io/multi_out_stream.zig").multiOutStream;
+pub const CWriter = @import("io/c_writer.zig").CWriter;
+pub const cWriter = @import("io/c_writer.zig").cWriter;
+/// Deprecated: use `CWriter`
+pub const COutStream = CWriter;
+/// Deprecated: use `cWriter`
+pub const cOutStream = cWriter;
+
+pub const CountingWriter = @import("io/counting_writer.zig").CountingWriter;
+pub const countingWriter = @import("io/counting_writer.zig").countingWriter;
+/// Deprecated: use `CountingWriter`
+pub const CountingOutStream = CountingWriter;
+/// Deprecated: use `countingWriter`
+pub const countingOutStream = countingWriter;
+
+pub const MultiWriter = @import("io/multi_writer.zig").MultiWriter;
+pub const multiWriter = @import("io/multi_writer.zig").multiWriter;
+/// Deprecated: use `MultiWriter`
+pub const MultiOutStream = MultiWriter;
+/// Deprecated: use `multiWriter`
+pub const multiOutStream = multiWriter;
 
 pub const BitInStream = @import("io/bit_in_stream.zig").BitInStream;
 pub const bitInStream = @import("io/bit_in_stream.zig").bitInStream;
 
-pub const BitOutStream = @import("io/bit_out_stream.zig").BitOutStream;
-pub const bitOutStream = @import("io/bit_out_stream.zig").bitOutStream;
+pub const BitWriter = @import("io/bit_writer.zig").BitWriter;
+pub const bitWriter = @import("io/bit_writer.zig").bitWriter;
+/// Deprecated: use `BitWriter`
+pub const BitOutStream = BitWriter;
+/// Deprecated: use `bitWriter`
+pub const bitOutStream = bitWriter;
 
 pub const Packing = @import("io/serialization.zig").Packing;
 
@@ -144,29 +166,34 @@ pub const BufferedAtomicFile = @import("io/buffered_atomic_file.zig").BufferedAt
 
 pub const StreamSource = @import("io/stream_source.zig").StreamSource;
 
-/// An OutStream that doesn't write to anything.
-pub const null_out_stream = @as(NullOutStream, .{ .context = {} });
+/// A Writer that doesn't write to anything.
+pub const null_writer = @as(NullWriter, .{ .context = {} });
+
+/// Deprecated: use `null_writer`
+pub const null_out_stream = null_writer;
 
-const NullOutStream = OutStream(void, error{}, dummyWrite);
+const NullWriter = Writer(void, error{}, dummyWrite);
+/// Deprecated: use NullWriter
+const NullOutStream = NullWriter;
 fn dummyWrite(context: void, data: []const u8) error{}!usize {
     return data.len;
 }
 
-test "null_out_stream" {
-    null_out_stream.writeAll("yay" ** 10) catch |err| switch (err) {};
+test "null_writer" {
+    null_writer.writeAll("yay" ** 10) catch |err| switch (err) {};
 }
 
 test "" {
     _ = @import("io/bit_in_stream.zig");
-    _ = @import("io/bit_out_stream.zig");
+    _ = @import("io/bit_writer.zig");
     _ = @import("io/buffered_atomic_file.zig");
     _ = @import("io/buffered_in_stream.zig");
-    _ = @import("io/buffered_out_stream.zig");
-    _ = @import("io/c_out_stream.zig");
-    _ = @import("io/counting_out_stream.zig");
+    _ = @import("io/buffered_writer.zig");
+    _ = @import("io/c_writer.zig");
+    _ = @import("io/counting_writer.zig");
     _ = @import("io/fixed_buffer_stream.zig");
     _ = @import("io/in_stream.zig");
-    _ = @import("io/out_stream.zig");
+    _ = @import("io/writer.zig");
     _ = @import("io/peek_stream.zig");
     _ = @import("io/seekable_stream.zig");
     _ = @import("io/serialization.zig");