Function peekStructPointer [src]

Obtains an unaligned pointer to the beginning of the stream, reinterpreted as a pointer to the provided type, without advancing the seek position. Asserts the buffer was initialized with a capacity at least @sizeOf(T). See also: takeStructPointer peekStruct

Prototype

pub fn peekStructPointer(r: *Reader, comptime T: type) Error!*align(1) T

Parameters

r: *ReaderT: type

Possible Errors

EndOfStream

ReadFailed

See the Reader implementation for detailed diagnostics.

Example

 test peekStructPointer {
    var r: Reader = .fixed(&.{ 0x12, 0x00, 0x34, 0x56 });
    const S = extern struct { a: u8, b: u16 };
    switch (native_endian) {
        .little => {
            try testing.expectEqual(@as(S, .{ .a = 0x12, .b = 0x5634 }), (try r.peekStructPointer(S)).*);
            try testing.expectEqual(@as(S, .{ .a = 0x12, .b = 0x5634 }), (try r.peekStructPointer(S)).*);
        },
        .big => {
            try testing.expectEqual(@as(S, .{ .a = 0x12, .b = 0x3456 }), (try r.peekStructPointer(S)).*);
            try testing.expectEqual(@as(S, .{ .a = 0x12, .b = 0x3456 }), (try r.peekStructPointer(S)).*);
        },
    }
}

Source

  pub fn peekStructPointer(r: *Reader, comptime T: type) Error!*align(1) T {
    // Only extern and packed structs have defined in-memory layout.
    comptime assert(@typeInfo(T).@"struct".layout != .auto);
    return @ptrCast(try r.peekArray(@sizeOf(T)));
}  