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const std = @import("std");
pub fn ExactSizeMatcher(comptime max_bytes: usize) type {
const a: u32 = 1000;
switch (max_bytes) {
1, 2, 4, 8, 12 => {},
else => {
@compileError("max_bytes must be 1, 2, 4, 8, or 12.");
},
}
const T = std.meta.Int(
.unsigned,
max_bytes * 8,
);
return struct {
pub fn match(str: anytype) T {
switch (str.len) {
1...max_bytes - 1 => {
var tmp = std.mem.zeroes([max_bytes]u8);
std.mem.copy(u8, &tmp, str[0..str.len]);
return std.mem.readIntNative(T, &tmp);
},
max_bytes => {
return std.mem.readIntSliceNative(T, str);
},
0 => {
return 0;
},
else => {
return std.math.maxInt(T);
},
}
}
pub fn case(comptime str: []const u8) T {
if (str.len < max_bytes) {
var bytes = std.mem.zeroes([max_bytes]u8);
const slice_bytes = std.mem.sliceAsBytes(str);
std.mem.copy(u8, &bytes, slice_bytes);
return std.mem.readIntNative(T, &bytes);
} else if (str.len == max_bytes) {
return std.mem.readIntNative(T, str[0..str.len]);
} else {
@compileError("str: \"" ++ str ++ "\" too long");
}
}
};
}
const eight = ExactSizeMatcher(8);
const expect = std.testing.expect;
test "ExactSizeMatcher 5 letter" {
const word = "yield";
try expect(eight.match(word) == eight.case("yield"));
try expect(eight.match(word) != eight.case("yields"));
}
test "ExactSizeMatcher 4 letter" {
const Four = ExactSizeMatcher(4);
const word = "from";
try expect(Four.match(word) == Four.case("from"));
try expect(Four.match(word) != Four.case("fro"));
}
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