diff --git a/lib/std/io/in_stream.zig b/lib/std/io/in_stream.zig index 2a03ba3037..6d24508f7b 100644 --- a/lib/std/io/in_stream.zig +++ b/lib/std/io/in_stream.zig @@ -184,35 +184,38 @@ pub fn InStream( return @bitCast(i8, try self.readByte()); } + /// Reads exactly `num_bytes` bytes and returns as an array. + /// `num_bytes` must be comptime-known + pub fn readBytesNoEof(self: Self, comptime num_bytes: usize) ![num_bytes]u8 { + var bytes: [num_bytes]u8 = undefined; + try self.readNoEof(&bytes); + return bytes; + } + /// Reads a native-endian integer pub fn readIntNative(self: Self, comptime T: type) !T { - var bytes: [(T.bit_count + 7) / 8]u8 = undefined; - try self.readNoEof(bytes[0..]); + const bytes = try self.readBytesNoEof((T.bit_count + 7) / 8); return mem.readIntNative(T, &bytes); } /// Reads a foreign-endian integer pub fn readIntForeign(self: Self, comptime T: type) !T { - var bytes: [(T.bit_count + 7) / 8]u8 = undefined; - try self.readNoEof(bytes[0..]); + const bytes = try self.readBytesNoEof((T.bit_count + 7) / 8); return mem.readIntForeign(T, &bytes); } pub fn readIntLittle(self: Self, comptime T: type) !T { - var bytes: [(T.bit_count + 7) / 8]u8 = undefined; - try self.readNoEof(bytes[0..]); + const bytes = try self.readBytesNoEof((T.bit_count + 7) / 8); return mem.readIntLittle(T, &bytes); } pub fn readIntBig(self: Self, comptime T: type) !T { - var bytes: [(T.bit_count + 7) / 8]u8 = undefined; - try self.readNoEof(bytes[0..]); + const bytes = try self.readBytesNoEof((T.bit_count + 7) / 8); return mem.readIntBig(T, &bytes); } pub fn readInt(self: Self, comptime T: type, endian: builtin.Endian) !T { - var bytes: [(T.bit_count + 7) / 8]u8 = undefined; - try self.readNoEof(bytes[0..]); + const bytes = try self.readBytesNoEof((T.bit_count + 7) / 8); return mem.readInt(T, &bytes, endian); } @@ -231,6 +234,18 @@ pub fn InStream( } } + /// Reads `slice.len` bytes from the stream and returns if they are the same as the passed slice + pub fn isBytes(self: Self, slice: []const u8) !bool { + var i: usize = 0; + var matches = true; + while (i < slice.len) : (i += 1) { + if (slice[i] != try self.readByte()) { + matches = false; + } + } + return matches; + } + pub fn readStruct(self: Self, comptime T: type) !T { // Only extern and packed structs have defined in-memory layout. comptime assert(@typeInfo(T).Struct.layout != builtin.TypeInfo.ContainerLayout.Auto); @@ -273,3 +288,9 @@ test "InStream" { }, undefined)) == .c); testing.expectError(error.EndOfStream, in_stream.readByte()); } + +test "InStream.isBytes" { + const in_stream = std.io.fixedBufferStream("foobar").inStream(); + testing.expectEqual(true, try in_stream.isBytes("foo")); + testing.expectEqual(false, try in_stream.isBytes("qux")); +}