thunderbird-patch-review

Easy-to-use patch review interface for Thunderbird

Contribute: ~marcc/thunderbird-review-plugin@lists.sr.ht

git clone git://mccd.space/thunderbird-patch-review

intraline.js (2653B)

 // Intra-line ("word level") diff highlighting: within a replacement block —
 // a run of deleted lines followed by a run of added lines — pair the lines
 // index-wise and mark the span that actually changed, computed as everything
 // between the common prefix and common suffix of the pair.
 
 /**
  * Changed spans for one del/add line pair, as ranges over the line text
  * (without the +/- prefix). Returns null when the lines share too little
  * (under ~25% of the longer line) for a partial highlight to mean anything.
  * A side whose range is empty (pure insertion/removal) should not be
  * highlighted; computeIntraline already filters those out.
  */
 export function pairRanges(delText, addText) {
   const max = Math.min(delText.length, addText.length);
   let prefix = 0;
   while (prefix < max && delText[prefix] === addText[prefix]) {
     prefix++;
   }
   let suffix = 0;
   while (
     suffix < max - prefix &&
     delText[delText.length - 1 - suffix] === addText[addText.length - 1 - suffix]
   ) {
     suffix++;
   }
   if ((prefix + suffix) * 4 < Math.max(delText.length, addText.length)) {
     return null;
   }
   return {
     del: [prefix, delText.length - suffix],
     add: [prefix, addText.length - suffix],
   };
 }
 
 const isNoNewlineMarker = (line) => line.origin === "ctx" && line.raw.startsWith("\\");
 
 /**
  * @param {Array<{origin: string, text: string, raw: string}>} lines hunk lines
  * @returns {Array<{start: number, end: number}|null>} per-line changed range
  *          over line.text, null where nothing (or everything) changed
  */
 export function computeIntraline(lines) {
   const result = new Array(lines.length).fill(null);
 
   let i = 0;
   while (i < lines.length) {
     if (lines[i].origin !== "del") {
       i++;
       continue;
     }
     const dels = [];
     while (i < lines.length && lines[i].origin === "del") {
       dels.push(i);
       i++;
     }
     // A "\ No newline at end of file" marker may sit between the runs.
     let j = i;
     while (j < lines.length && isNoNewlineMarker(lines[j])) {
       j++;
     }
     const adds = [];
     while (j < lines.length && lines[j].origin === "add") {
       adds.push(j);
       j++;
     }
 
     const pairs = Math.min(dels.length, adds.length);
     for (let k = 0; k < pairs; k++) {
       const ranges = pairRanges(lines[dels[k]].text, lines[adds[k]].text);
       if (!ranges) {
         continue;
       }
       if (ranges.del[1] > ranges.del[0]) {
         result[dels[k]] = { start: ranges.del[0], end: ranges.del[1] };
       }
       if (ranges.add[1] > ranges.add[0]) {
         result[adds[k]] = { start: ranges.add[0], end: ranges.add[1] };
       }
     }
   }
 
   return result;
 }