var MAX_MATRIX_SIZE = 256 * 256;
- function levenshteinMatrix(s, t) {
+ function levenshteinMatrix(s, t, ins, del, sub) {
/** Calculate the Levenshtein edit distance matrix for two strings
- The matrix is returned as a flat unsigned typed array.
+ The matrix is returned as a flat typed array.
Following http://en.wikipedia.org/wiki/Levenshtein_distance
*/
if (s[i - 1] === t[j - 1])
d[n * i + j] = d[n * (i - 1) + j - 1];
else
- d[n * i + j] = 1 + Math.min(d[n * (i - 1) + j ],
- d[n * i + j - 1],
- d[n * (i - 1) + j - 1]);
+ d[n * i + j] = Math.min(del + d[n * (i - 1) + j ],
+ ins + d[n * i + j - 1],
+ sub + d[n * (i - 1) + j - 1]);
return d;
}
function diff(s, t) {
/** Create a diff between string s and t */
- return editPath(levenshteinMatrix(s, t), t);
+ return editPath(levenshteinMatrix(s, t, 2, 2, 3), t);
}
function patch(edits, s) {
/** Apply the list of edits to s */
+ var edit;
var i;
- for (i = 0; i < edits.length; ++i) {
- var edit = edits[i];
- switch (edit[0]) {
- case "sub":
- s = s.slice(0, edit[1]) + edit[2] + s.slice(edit[1] + 1);
- break;
- case "ins":
- s = s.slice(0, edit[1]) + edit[2] + s.slice(edit[1]);
- break;
- case "del":
- s = s.slice(0, edit[1]) + s.slice(edit[1] + 1);
- break;
+
+ if (Array.isArray(s)) {
+ for (i = 0; i < edits.length; ++i) {
+ edit = edits[i];
+ switch (edit[0]) {
+ case "sub":
+ s[edit[1]] = edit[2];
+ break;
+ case "ins":
+ s.splice(edit[1], 0, edit[2]);
+ break;
+ case "del":
+ s.splice(edit[1], 1);
+ break;
+ }
+ }
+ } else {
+ for (i = 0; i < edits.length; ++i) {
+ edit = edits[i];
+ switch (edit[0]) {
+ case "sub":
+ s = s.slice(0, edit[1]) + edit[2] + s.slice(edit[1] + 1);
+ break;
+ case "ins":
+ s = s.slice(0, edit[1]) + edit[2] + s.slice(edit[1]);
+ break;
+ case "del":
+ s = s.slice(0, edit[1]) + s.slice(edit[1] + 1);
+ break;
+ }
}
}
return s;
}
+ var MULTI = /[\uD800-\uDBFF][\uDC00-\uDFFF]|[\u0300-\u036F\u1DC0-\u1DFF\u20D0-\u20FF\uFE20-\uFE2F]/;
+
+ var GLYPH = /([\0-\u02FF\u0370-\u1DBF\u1E00-\u20CF\u2100-\uD7FF\uDC00-\uFE1F\uFE30-\uFFFF]|[\uD800-\uDBFF][\uDC00-\uDFFF]|[\uD800-\uDBFF])([\u0300-\u036F\u1DC0-\u1DFF\u20D0-\u20FF\uFE20-\uFE2F]*)/g;
+
function diffLerp(a, b, p) {
- /** Interpolate between two strings based on edit distance
+ /** Interpolate between two strings based on edit operations
This interpolation algorithm applys a partial edit of one
string into the other. This produces nice looking results,
longer than a few hundred characters.
*/
+ // If given strings with astral codepoints or combining
+ // characters, split them into arrays of "glyphs" first,
+ // do the edit on the list of "glyphs", and rejoin them.
+ //
+ // This split is not perfect for all languages, but at least
+ // it won't create invalid surrogate pairs or orphaned
+ // combining characters.
+ if (a.match && a.match(MULTI) || b.match && b.match(MULTI)) {
+ var ca = a.match(GLYPH) || [];
+ var cb = b.match(GLYPH) || [];
+ return diffLerp(ca, cb, p).join("");
+ }
+
// The edit path works from the string end, forwards, because
// that's how Levenshtein edits work. To match LTR reading
// direction (and the behavior of fastLerp), swap the strings
is clamped to an integer.
For example, numericLerp("0.0", "100", 0.123) === "12.3"
- because the "." in "0.0" is intepreted as a decimal point.
- But numericLerp("0.", "100.", 0.123) === "12." because the
- strings are interpreted as integers followed by a full
- stop.
+ because the "." in "0.0" is interpreted as a decimal
+ point. But numericLerp("0.", "100.", 0.123) === "12."
+ because the strings are interpreted as integers followed
+ by a full stop.
Calling this functions on strings that differ in more than
numerals gives undefined results.
front of one string with another. This approach is fast
but does not look good when the strings are similar.
*/
- var alen = Math.round(a.length * p);
- var blen = Math.round(b.length * p);
- return b.substring(0, blen) + a.substring(alen, a.length);
+
+ // TODO: Consider fast-pathing this even more for very large
+ // strings, e.g. in the megabyte range. These are large enough
+ // that
+ if (a.match(MULTI) || b.match(MULTI)) {
+ var ca = a.match(GLYPH) || [];
+ var cb = b.match(GLYPH) || [];
+ var calen = Math.round(ca.length * p);
+ var cblen = Math.round(cb.length * p);
+ var r = cb.slice(0, cblen);
+ r.push.apply(r, ca.slice(calen, ca.length));
+ return r.join("");
+ } else {
+ var alen = Math.round(a.length * p);
+ var blen = Math.round(b.length * p);
+ return b.substring(0, blen) + a.substring(alen, a.length);
+ }
}
function lerp(a, b, p) {
projects / string-lerp.git / blobdiff