gardhr
commented
4 years ago Try something like this:
function reverse(str) {
var result = "";
var smx = str.length;
var sdx = 0;
/*
Can't start at the end because each segment depends on the
previous one. So build up a list of lengths first instead.
*/
var counts = [];
for (;;) {
var skip = str.codePointAt(sdx) <= 0xffff ? 1 : 2;
counts.push(skip);
sdx += skip;
if (sdx >= smx) break;
}
var cmx = counts.length;
while (cmx--) {
var skip = counts[cmx];
/*
Now we know how much to hop backward for the next grapheme.
Write the first segment, then the second (if present).
*/
var hop = skip;
while (hop) result += str[smx - hop--];
/*
Move on to the next glyph. (Bounds-checking won't be needed
here since the counts array holds an accurate list of widths.)
*/
smx -= skip;
}
return result;
}
kgryte
Checklist
Description
Encountered an error when attempting to use
@stdlib/string/reverseto reverse a string which includes extended grapheme clusters. While the implementation does account for Unicode surrogate pairs and combining marks, extended grapheme clusters do not appear supported.Addressing this issue may require using a Unicode segmentation algorithm, as discussed in the Unicode standard. One can find reference implementations in Rust and elsewhere.
Related Issues
Related issues #295.
Questions
No.
Other
N/A
Demo
N/A
Reproduction
In order to reproduce this bug, do the following:
Expected Results
The reversed string to account for extended grapheme clusters.
Actual Results
N/A
Environments
The following environments are affected: