/
diffLines.ts
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/
diffLines.ts
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/**
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
import * as diff from 'diff-sequences'
import { DIFF_DELETE, DIFF_EQUAL, DIFF_INSERT, Diff } from './cleanupSemantic'
import {
joinAlignedDiffsExpand,
joinAlignedDiffsNoExpand,
} from './joinAlignedDiffs'
import { normalizeDiffOptions } from './normalizeDiffOptions'
import type { DiffOptions, DiffOptionsNormalized } from './types'
function isEmptyString(lines: Array<string>) {
return lines.length === 1 && lines[0].length === 0
}
interface ChangeCounts {
a: number
b: number
}
function countChanges(diffs: Array<Diff>): ChangeCounts {
let a = 0
let b = 0
diffs.forEach((diff) => {
switch (diff[0]) {
case DIFF_DELETE:
a += 1
break
case DIFF_INSERT:
b += 1
break
}
})
return { a, b }
}
function printAnnotation({
aAnnotation,
aColor,
aIndicator,
bAnnotation,
bColor,
bIndicator,
includeChangeCounts,
omitAnnotationLines,
}: DiffOptionsNormalized,
changeCounts: ChangeCounts): string {
if (omitAnnotationLines)
return ''
let aRest = ''
let bRest = ''
if (includeChangeCounts) {
const aCount = String(changeCounts.a)
const bCount = String(changeCounts.b)
// Padding right aligns the ends of the annotations.
const baAnnotationLengthDiff = bAnnotation.length - aAnnotation.length
const aAnnotationPadding = ' '.repeat(Math.max(0, baAnnotationLengthDiff))
const bAnnotationPadding = ' '.repeat(Math.max(0, -baAnnotationLengthDiff))
// Padding left aligns the ends of the counts.
const baCountLengthDiff = bCount.length - aCount.length
const aCountPadding = ' '.repeat(Math.max(0, baCountLengthDiff))
const bCountPadding = ' '.repeat(Math.max(0, -baCountLengthDiff))
aRest = `${aAnnotationPadding} ${aIndicator} ${aCountPadding}${aCount}`
bRest = `${bAnnotationPadding} ${bIndicator} ${bCountPadding}${bCount}`
}
const a = `${aIndicator} ${aAnnotation}${aRest}`
const b = `${bIndicator} ${bAnnotation}${bRest}`
return `${aColor(a)}\n${bColor(b)}\n\n`
}
export function printDiffLines(diffs: Array<Diff>,
options: DiffOptionsNormalized): string {
return printAnnotation(options, countChanges(diffs))
+ (options.expand
? joinAlignedDiffsExpand(diffs, options)
: joinAlignedDiffsNoExpand(diffs, options))
}
// Compare two arrays of strings line-by-line. Format as comparison lines.
export function diffLinesUnified(aLines: Array<string>,
bLines: Array<string>,
options?: DiffOptions): string {
return printDiffLines(
diffLinesRaw(
isEmptyString(aLines) ? [] : aLines,
isEmptyString(bLines) ? [] : bLines,
),
normalizeDiffOptions(options),
)
}
// Given two pairs of arrays of strings:
// Compare the pair of comparison arrays line-by-line.
// Format the corresponding lines in the pair of displayable arrays.
export function diffLinesUnified2(aLinesDisplay: Array<string>,
bLinesDisplay: Array<string>,
aLinesCompare: Array<string>,
bLinesCompare: Array<string>,
options?: DiffOptions): string {
if (isEmptyString(aLinesDisplay) && isEmptyString(aLinesCompare)) {
aLinesDisplay = []
aLinesCompare = []
}
if (isEmptyString(bLinesDisplay) && isEmptyString(bLinesCompare)) {
bLinesDisplay = []
bLinesCompare = []
}
if (
aLinesDisplay.length !== aLinesCompare.length
|| bLinesDisplay.length !== bLinesCompare.length
) {
// Fall back to diff of display lines.
return diffLinesUnified(aLinesDisplay, bLinesDisplay, options)
}
const diffs = diffLinesRaw(aLinesCompare, bLinesCompare)
// Replace comparison lines with displayable lines.
let aIndex = 0
let bIndex = 0
diffs.forEach((diff: Diff) => {
switch (diff[0]) {
case DIFF_DELETE:
diff[1] = aLinesDisplay[aIndex]
aIndex += 1
break
case DIFF_INSERT:
diff[1] = bLinesDisplay[bIndex]
bIndex += 1
break
default:
diff[1] = bLinesDisplay[bIndex]
aIndex += 1
bIndex += 1
}
})
return printDiffLines(diffs, normalizeDiffOptions(options))
}
// Compare two arrays of strings line-by-line.
export function diffLinesRaw(aLines: Array<string>,
bLines: Array<string>): Array<Diff> {
const aLength = aLines.length
const bLength = bLines.length
const isCommon = (aIndex: number, bIndex: number) =>
aLines[aIndex] === bLines[bIndex]
const diffs: Array<Diff> = []
let aIndex = 0
let bIndex = 0
const foundSubsequence = (
nCommon: number,
aCommon: number,
bCommon: number,
) => {
for (; aIndex !== aCommon; aIndex += 1)
diffs.push(new Diff(DIFF_DELETE, aLines[aIndex]))
for (; bIndex !== bCommon; bIndex += 1)
diffs.push(new Diff(DIFF_INSERT, bLines[bIndex]))
for (; nCommon !== 0; nCommon -= 1, aIndex += 1, bIndex += 1)
diffs.push(new Diff(DIFF_EQUAL, bLines[bIndex]))
}
// @ts-expect-error wrong bundling
const diffSequences = diff.default.default || diff.default
diffSequences(aLength, bLength, isCommon, foundSubsequence)
// After the last common subsequence, push remaining change items.
for (; aIndex !== aLength; aIndex += 1)
diffs.push(new Diff(DIFF_DELETE, aLines[aIndex]))
for (; bIndex !== bLength; bIndex += 1)
diffs.push(new Diff(DIFF_INSERT, bLines[bIndex]))
return diffs
}