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initial commit of Str.trimLeft

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This commit is contained in:
Michael Downey 2021-11-09 14:25:24 -05:00
parent 35df58c18f
commit 1bc278d962
13 changed files with 159 additions and 7 deletions
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111
compiler/builtins/bitcode/src/str.zig
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@ -1547,6 +1547,46 @@ pub fn strTrim(string: RocStr) callconv(.C) RocStr {
return RocStr.empty();
}
pub fn strTrimLeft(string: RocStr) callconv(.C) RocStr {
if (string.str_bytes) |bytes_ptr| {
const leading_bytes = countLeadingWhitespaceBytes(string);
const original_len = string.len();
if (original_len == leading_bytes) {
string.deinit();
return RocStr.empty();
}
const new_len = original_len - leading_bytes;
const small_or_shared = new_len <= SMALL_STR_MAX_LENGTH or !string.isRefcountOne();
if (small_or_shared) {
return RocStr.init(string.asU8ptr() + leading_bytes, new_len);
}
// nonempty, large, and unique:
if (leading_bytes > 0) {
var i: usize = 0;
while (i < new_len) : (i += 1) {
if (i >= leading_bytes - 1) {
const dest = bytes_ptr + i;
const source = dest + leading_bytes;
@memcpy(dest, source, 1);
}
}
}
var new_string = string;
new_string.str_len = new_len;
return new_string;
}
return RocStr.empty();
}
fn countLeadingWhitespaceBytes(string: RocStr) usize {
var byte_count: usize = 0;
@ -1712,6 +1752,77 @@ test "strTrim: small to small" {
try expect(trimmed.isSmallStr());
}
test "strTrimLeft: empty" {
const trimmedEmpty = strTrim(RocStr.empty());
try expect(trimmedEmpty.eq(RocStr.empty()));
}
test "strTrimLeft: blank" {
const original_bytes = " ";
const original = RocStr.init(original_bytes, original_bytes.len);
defer original.deinit();
const trimmed = strTrim(original);
try expect(trimmed.eq(RocStr.empty()));
}
test "strTrimLeft: large to large" {
const original_bytes = " hello giant world ";
const original = RocStr.init(original_bytes, original_bytes.len);
defer original.deinit();
try expect(!original.isSmallStr());
const expected_bytes = "hello giant world ";
const expected = RocStr.init(expected_bytes, expected_bytes.len);
defer expected.deinit();
try expect(!expected.isSmallStr());
const trimmed = strTrim(original);
try expect(trimmed.eq(expected));
}
test "strTrimLeft: large to small" {
const original_bytes = " hello world ";
const original = RocStr.init(original_bytes, original_bytes.len);
defer original.deinit();
try expect(!original.isSmallStr());
const expected_bytes = "hello world ";
const expected = RocStr.init(expected_bytes, expected_bytes.len);
defer expected.deinit();
try expect(expected.isSmallStr());
const trimmed = strTrim(original);
try expect(trimmed.eq(expected));
try expect(trimmed.isSmallStr());
}
test "strTrimLeft: small to small" {
const original_bytes = " hello world ";
const original = RocStr.init(original_bytes, original_bytes.len);
defer original.deinit();
try expect(original.isSmallStr());
const expected_bytes = "hello world ";
const expected = RocStr.init(expected_bytes, expected_bytes.len);
defer expected.deinit();
try expect(expected.isSmallStr());
const trimmed = strTrim(original);
try expect(trimmed.eq(expected));
try expect(trimmed.isSmallStr());
}
test "ReverseUtf8View: hello world" {
const original_bytes = "hello world";
const expected_bytes = "dlrow olleh";