diff
Version:
A JavaScript text diff implementation.
258 lines (257 loc) • 12.9 kB
JavaScript
import { hasOnlyWinLineEndings, hasOnlyUnixLineEndings } from '../util/string.js';
import { isWin, isUnix, unixToWin, winToUnix } from './line-endings.js';
import { parsePatch } from './parse.js';
import distanceIterator from '../util/distance-iterator.js';
/**
* attempts to apply a unified diff patch.
*
* Hunks are applied first to last.
* `applyPatch` first tries to apply the first hunk at the line number specified in the hunk header, and with all context lines matching exactly.
* If that fails, it tries scanning backwards and forwards, one line at a time, to find a place to apply the hunk where the context lines match exactly.
* If that still fails, and `fuzzFactor` is greater than zero, it increments the maximum number of mismatches (missing, extra, or changed context lines) that there can be between the hunk context and a region where we are trying to apply the patch such that the hunk will still be considered to match.
* Regardless of `fuzzFactor`, lines to be deleted in the hunk *must* be present for a hunk to match, and the context lines *immediately* before and after an insertion must match exactly.
*
* Once a hunk is successfully fitted, the process begins again with the next hunk.
* Regardless of `fuzzFactor`, later hunks must be applied later in the file than earlier hunks.
*
* If a hunk cannot be successfully fitted *anywhere* with fewer than `fuzzFactor` mismatches, `applyPatch` fails and returns `false`.
*
* If a hunk is successfully fitted but not at the line number specified by the hunk header, all subsequent hunks have their target line number adjusted accordingly.
* (e.g. if the first hunk is applied 10 lines below where the hunk header said it should fit, `applyPatch` will *start* looking for somewhere to apply the second hunk 10 lines below where its hunk header says it goes.)
*
* If the patch was applied successfully, returns a string containing the patched text.
* If the patch could not be applied (because some hunks in the patch couldn't be fitted to the text in `source`), `applyPatch` returns false.
*
* @param patch a string diff or the output from the `parsePatch` or `structuredPatch` methods.
*/
export function applyPatch(source, patch, options = {}) {
let patches;
if (typeof patch === 'string') {
patches = parsePatch(patch);
}
else if (Array.isArray(patch)) {
patches = patch;
}
else {
patches = [patch];
}
if (patches.length > 1) {
throw new Error('applyPatch only works with a single input.');
}
return applyStructuredPatch(source, patches[0], options);
}
function applyStructuredPatch(source, patch, options = {}) {
if (options.autoConvertLineEndings || options.autoConvertLineEndings == null) {
if (hasOnlyWinLineEndings(source) && isUnix(patch)) {
patch = unixToWin(patch);
}
else if (hasOnlyUnixLineEndings(source) && isWin(patch)) {
patch = winToUnix(patch);
}
}
// Apply the diff to the input
const lines = source.split('\n'), hunks = patch.hunks, compareLine = options.compareLine || ((lineNumber, line, operation, patchContent) => line === patchContent), fuzzFactor = options.fuzzFactor || 0;
let minLine = 0;
if (fuzzFactor < 0 || !Number.isInteger(fuzzFactor)) {
throw new Error('fuzzFactor must be a non-negative integer');
}
// Special case for empty patch.
if (!hunks.length) {
return source;
}
// Before anything else, handle EOFNL insertion/removal. If the patch tells us to make a change
// to the EOFNL that is redundant/impossible - i.e. to remove a newline that's not there, or add a
// newline that already exists - then we either return false and fail to apply the patch (if
// fuzzFactor is 0) or simply ignore the problem and do nothing (if fuzzFactor is >0).
// If we do need to remove/add a newline at EOF, this will always be in the final hunk:
let prevLine = '', removeEOFNL = false, addEOFNL = false;
for (let i = 0; i < hunks[hunks.length - 1].lines.length; i++) {
const line = hunks[hunks.length - 1].lines[i];
if (line[0] == '\\') {
if (prevLine[0] == '+') {
removeEOFNL = true;
}
else if (prevLine[0] == '-') {
addEOFNL = true;
}
}
prevLine = line;
}
if (removeEOFNL) {
if (addEOFNL) {
// This means the final line gets changed but doesn't have a trailing newline in either the
// original or patched version. In that case, we do nothing if fuzzFactor > 0, and if
// fuzzFactor is 0, we simply validate that the source file has no trailing newline.
if (!fuzzFactor && lines[lines.length - 1] == '') {
return false;
}
}
else if (lines[lines.length - 1] == '') {
lines.pop();
}
else if (!fuzzFactor) {
return false;
}
}
else if (addEOFNL) {
if (lines[lines.length - 1] != '') {
lines.push('');
}
else if (!fuzzFactor) {
return false;
}
}
/**
* Checks if the hunk can be made to fit at the provided location with at most `maxErrors`
* insertions, substitutions, or deletions, while ensuring also that:
* - lines deleted in the hunk match exactly, and
* - wherever an insertion operation or block of insertion operations appears in the hunk, the
* immediately preceding and following lines of context match exactly
*
* `toPos` should be set such that lines[toPos] is meant to match hunkLines[0].
*
* If the hunk can be applied, returns an object with properties `oldLineLastI` and
* `replacementLines`. Otherwise, returns null.
*/
function applyHunk(hunkLines, toPos, maxErrors, hunkLinesI = 0, lastContextLineMatched = true, patchedLines = [], patchedLinesLength = 0) {
let nConsecutiveOldContextLines = 0;
let nextContextLineMustMatch = false;
for (; hunkLinesI < hunkLines.length; hunkLinesI++) {
const hunkLine = hunkLines[hunkLinesI], operation = (hunkLine.length > 0 ? hunkLine[0] : ' '), content = (hunkLine.length > 0 ? hunkLine.substr(1) : hunkLine);
if (operation === '-') {
if (compareLine(toPos + 1, lines[toPos], operation, content)) {
toPos++;
nConsecutiveOldContextLines = 0;
}
else {
if (!maxErrors || lines[toPos] == null) {
return null;
}
patchedLines[patchedLinesLength] = lines[toPos];
return applyHunk(hunkLines, toPos + 1, maxErrors - 1, hunkLinesI, false, patchedLines, patchedLinesLength + 1);
}
}
if (operation === '+') {
if (!lastContextLineMatched) {
return null;
}
patchedLines[patchedLinesLength] = content;
patchedLinesLength++;
nConsecutiveOldContextLines = 0;
nextContextLineMustMatch = true;
}
if (operation === ' ') {
nConsecutiveOldContextLines++;
patchedLines[patchedLinesLength] = lines[toPos];
if (compareLine(toPos + 1, lines[toPos], operation, content)) {
patchedLinesLength++;
lastContextLineMatched = true;
nextContextLineMustMatch = false;
toPos++;
}
else {
if (nextContextLineMustMatch || !maxErrors) {
return null;
}
// Consider 3 possibilities in sequence:
// 1. lines contains a *substitution* not included in the patch context, or
// 2. lines contains an *insertion* not included in the patch context, or
// 3. lines contains a *deletion* not included in the patch context
// The first two options are of course only possible if the line from lines is non-null -
// i.e. only option 3 is possible if we've overrun the end of the old file.
return (lines[toPos] && (applyHunk(hunkLines, toPos + 1, maxErrors - 1, hunkLinesI + 1, false, patchedLines, patchedLinesLength + 1) || applyHunk(hunkLines, toPos + 1, maxErrors - 1, hunkLinesI, false, patchedLines, patchedLinesLength + 1)) || applyHunk(hunkLines, toPos, maxErrors - 1, hunkLinesI + 1, false, patchedLines, patchedLinesLength));
}
}
}
// Before returning, trim any unmodified context lines off the end of patchedLines and reduce
// toPos (and thus oldLineLastI) accordingly. This allows later hunks to be applied to a region
// that starts in this hunk's trailing context.
patchedLinesLength -= nConsecutiveOldContextLines;
toPos -= nConsecutiveOldContextLines;
patchedLines.length = patchedLinesLength;
return {
patchedLines,
oldLineLastI: toPos - 1
};
}
const resultLines = [];
// Search best fit offsets for each hunk based on the previous ones
let prevHunkOffset = 0;
for (let i = 0; i < hunks.length; i++) {
const hunk = hunks[i];
let hunkResult;
const maxLine = lines.length - hunk.oldLines + fuzzFactor;
let toPos;
for (let maxErrors = 0; maxErrors <= fuzzFactor; maxErrors++) {
toPos = hunk.oldStart + prevHunkOffset - 1;
const iterator = distanceIterator(toPos, minLine, maxLine);
for (; toPos !== undefined; toPos = iterator()) {
hunkResult = applyHunk(hunk.lines, toPos, maxErrors);
if (hunkResult) {
break;
}
}
if (hunkResult) {
break;
}
}
if (!hunkResult) {
return false;
}
// Copy everything from the end of where we applied the last hunk to the start of this hunk
for (let i = minLine; i < toPos; i++) {
resultLines.push(lines[i]);
}
// Add the lines produced by applying the hunk:
for (let i = 0; i < hunkResult.patchedLines.length; i++) {
const line = hunkResult.patchedLines[i];
resultLines.push(line);
}
// Set lower text limit to end of the current hunk, so next ones don't try
// to fit over already patched text
minLine = hunkResult.oldLineLastI + 1;
// Note the offset between where the patch said the hunk should've applied and where we
// applied it, so we can adjust future hunks accordingly:
prevHunkOffset = toPos + 1 - hunk.oldStart;
}
// Copy over the rest of the lines from the old text
for (let i = minLine; i < lines.length; i++) {
resultLines.push(lines[i]);
}
return resultLines.join('\n');
}
/**
* applies one or more patches.
*
* `patch` may be either an array of structured patch objects, or a string representing a patch in unified diff format (which may patch one or more files).
*
* This method will iterate over the contents of the patch and apply to data provided through callbacks. The general flow for each patch index is:
*
* - `options.loadFile(index, callback)` is called. The caller should then load the contents of the file and then pass that to the `callback(err, data)` callback. Passing an `err` will terminate further patch execution.
* - `options.patched(index, content, callback)` is called once the patch has been applied. `content` will be the return value from `applyPatch`. When it's ready, the caller should call `callback(err)` callback. Passing an `err` will terminate further patch execution.
*
* Once all patches have been applied or an error occurs, the `options.complete(err)` callback is made.
*/
export function applyPatches(uniDiff, options) {
const spDiff = typeof uniDiff === 'string' ? parsePatch(uniDiff) : uniDiff;
let currentIndex = 0;
function processIndex() {
const index = spDiff[currentIndex++];
if (!index) {
return options.complete();
}
options.loadFile(index, function (err, data) {
if (err) {
return options.complete(err);
}
const updatedContent = applyPatch(data, index, options);
options.patched(index, updatedContent, function (err) {
if (err) {
return options.complete(err);
}
processIndex();
});
});
}
processIndex();
}