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add substringUnsafe in zig

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Folkert 2022-07-03 15:10:14 +02:00
parent 3cd56c3184
commit 45eb8b9d77
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42
crates/compiler/builtins/bitcode/src/str.zig
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@ -1188,6 +1188,48 @@ pub fn countBytes(string: RocStr) callconv(.C) usize {
return string.len();
}
pub fn substringUnsafe(string: RocStr, start: usize, length: usize) callconv(.C) RocStr {
const slice = string.asSlice()[start .. start + length];
return RocStr.fromSlice(slice);
}
test "substringUnsafe: start" {
const str = RocStr.fromSlice("abcdef");
defer str.deinit();
const expected = RocStr.fromSlice("abc");
defer expected.deinit();
const actual = substringUnsafe(str, 0, 3);
try expect(RocStr.eq(actual, expected));
}
test "substringUnsafe: middle" {
const str = RocStr.fromSlice("abcdef");
defer str.deinit();
const expected = RocStr.fromSlice("bcd");
defer expected.deinit();
const actual = substringUnsafe(str, 1, 3);
try expect(RocStr.eq(actual, expected));
}
test "substringUnsafe: end" {
const str = RocStr.fromSlice("a string so long it is heap-allocated");
defer str.deinit();
const expected = RocStr.fromSlice("heap-allocated");
defer expected.deinit();
const actual = substringUnsafe(str, 23, 37 - 23);
try expect(RocStr.eq(actual, expected));
}
// Str.startsWith
pub fn startsWith(string: RocStr, prefix: RocStr) callconv(.C) bool {
const bytes_len = string.len();