language-servers/roc
1
0
Fork 0
mirror of https://github.com/roc-lang/roc.git synced 2025-09-26 21:39:07 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 6

use nullable index for reverse iterator

Browse source
This commit is contained in:
Dan Knutson 2021-10-25 19:39:38 -05:00
parent 6f49f355dd
commit bf1b597369
1 changed files with 22 additions and 19 deletions
Download patch file Download diff file Expand all files Collapse all files

41
compiler/builtins/bitcode/src/str.zig
View file

@ -1582,7 +1582,7 @@ const ReverseUtf8View = struct {
pub fn iterator(s: ReverseUtf8View) ReverseUtf8Iterator {
return ReverseUtf8Iterator{
.bytes = s.bytes,
.i = s.bytes.len,
.i = if (s.bytes.len > 0) s.bytes.len - 1 else null,
};
}
};
@ -1590,28 +1590,31 @@ const ReverseUtf8View = struct {
/// A backwards version of Utf8Iterator from std.unicode
const ReverseUtf8Iterator = struct {
bytes: []const u8,
// NOTE
// i points to one after the current begin byte,
// and 0 signifies 'done'
i: usize,
// NOTE null signifies complete/empty
i: ?usize,
pub fn nextCodepointSlice(it: *ReverseUtf8Iterator) ?[]const u8 {
if (it.i == 0) {
if (it.i) |index| {
var i = index;
// NOTE this relies on the string being valid utf8 to not run off the end
while (!utf8BeginByte(it.bytes[i])) {
i -= 1;
}
const cp_len = unicode.utf8ByteSequenceLength(it.bytes[i]) catch unreachable;
const slice = it.bytes[i .. i + cp_len];
if (i == 0) {
it.i = null;
} else {
it.i = i - 1;
}
return slice;
} else {
return null;
}
// NOTE this relies on the string being valid utf8 to not run off the end
while (!utf8BeginByte(it.bytes[it.i - 1])) {
it.i -= 1;
}
const begin_byte = it.i - 1;
const cp_len = unicode.utf8ByteSequenceLength(it.bytes[begin_byte]) catch unreachable;
const slice = it.bytes[begin_byte .. begin_byte + cp_len];
it.i -= 1;
return slice;
}
pub fn nextCodepoint(it: *ReverseUtf8Iterator) ?u21 {