João Salavisa
68 lines
2.5 KiB
JavaScript
68 lines
2.5 KiB
JavaScript
/**
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* Parse `git diff --unified=0` into the set of line numbers a change ADDED, so a
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* lint finding can be attributed to the change that introduced it rather than to
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* the file it happens to live in.
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*
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* This is what lets the i18n literal guard apply repo-wide to new code without
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* demanding that the surrounding legacy file be migrated first — the same model
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* as `golangci-lint --new-from-rev`, which this repo already uses for Go.
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*/
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/** Hunk header: `@@ -oldStart[,oldCount] +newStart[,newCount] @@ optional context` */
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const HUNK = /^@@ -\d+(?:,\d+)? \+(\d+)(?:,(\d+))? @@/;
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/**
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* Map of repo-relative path -> array of inclusive `[start, end]` line ranges that
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* the diff added, in the NEW file's numbering.
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*
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* Deleted files and pure-deletion hunks contribute nothing: there is no new line
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* to attribute a finding to.
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*
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* @param {string} diffText output of `git diff --unified=0 <base>...<head>`
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* @returns {Map<string, Array<[number, number]>>}
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*/
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export function parseAddedLineRanges(diffText) {
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const ranges = new Map();
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let current = null;
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for (const line of diffText.split("\n")) {
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// Every file entry starts here, so reset first. Entries that emit no `+++`
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// header at all — a 100%-similarity rename, a binary file, a mode-only
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// change — would otherwise leave the PREVIOUS file selected, and any hunk
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// that followed would be attributed to it. Not reachable with today's git
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// output, but it is a one-line invariant instead of a standing assumption.
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if (line.startsWith("diff --git ")) {
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current = null;
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continue;
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}
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if (line.startsWith("+++ ")) {
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const target = line.slice(4).trim();
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// `+++ /dev/null` marks a deletion; `+++ b/path` is the new file.
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current = target === "/dev/null" ? null : target.replace(/^b\//, "");
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if (current && !ranges.has(current)) ranges.set(current, []);
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continue;
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}
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if (!current || !line.startsWith("@@")) continue;
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const match = HUNK.exec(line);
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if (!match) continue;
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const start = Number(match[1]);
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// A missing count means exactly one line; an explicit 0 means deletion-only.
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const count = match[2] === undefined ? 1 : Number(match[2]);
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if (count > 0) ranges.get(current).push([start, start + count - 1]);
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}
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return ranges;
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}
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/**
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* Whether `line` falls inside any of `ranges`.
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*
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* @param {Array<[number, number]>} ranges
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* @param {number} line
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*/
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export function lineInRanges(ranges, line) {
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if (!ranges) return false;
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return ranges.some(([start, end]) => line >= start && line <= end);
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}
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