improve performance, alternative approach (+149% throughput and more) #38
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,105 +1,164 @@ | ||
| import ansiStyles from 'ansi-styles'; | ||
| import isFullwidthCodePoint from 'is-fullwidth-code-point'; | ||
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| // \x1b and \x9b | ||
| const ESCAPES = new Set([27, 155]); | ||
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| const CHAR_CODE_0 = '0'.charCodeAt(0); | ||
| const CHAR_CODE_9 = '9'.charCodeAt(0); | ||
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| const endCodesSet = new Set(); | ||
| const endCodesMap = new Map(); | ||
| for (const [start, end] of ansiStyles.codes) { | ||
| endCodesSet.add(ansiStyles.color.ansi(end)); | ||
| endCodesMap.set(ansiStyles.color.ansi(start), ansiStyles.color.ansi(end)); | ||
| } | ||
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| function getEndCode(code) { | ||
| if (endCodesSet.has(code)) { | ||
| return code; | ||
| } | ||
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| if (endCodesMap.has(code)) { | ||
| return endCodesMap.get(code); | ||
| } | ||
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| code = code.slice(2); | ||
| if (code.includes(';')) { | ||
| code = code[0] + '0'; | ||
| } | ||
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| const returnValue = ansiStyles.codes.get(Number.parseInt(code, 10)); | ||
| if (returnValue) { | ||
| return ansiStyles.color.ansi(returnValue); | ||
| } | ||
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| return ansiStyles.reset.open; | ||
| } | ||
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| function findNumberIndex(string) { | ||
| for (let index = 0; index < string.length; index++) { | ||
| const charCode = string.charCodeAt(index); | ||
| if (charCode >= CHAR_CODE_0 && charCode <= CHAR_CODE_9) { | ||
| return index; | ||
| } | ||
| } | ||
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| return -1; | ||
| } | ||
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| function parseAnsiCode(string, offset) { | ||
| string = string.slice(offset, offset + 19); | ||
| const startIndex = findNumberIndex(string); | ||
| if (startIndex !== -1) { | ||
| let endIndex = string.indexOf('m', startIndex); | ||
| if (endIndex === -1) { | ||
| endIndex = string.length; | ||
| } | ||
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| return string.slice(0, endIndex + 1); | ||
| } | ||
| } | ||
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| function tokenize(string, endChar = Number.POSITIVE_INFINITY) { | ||
| const returnValue = []; | ||
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| let index = 0; | ||
| let visibleCount = 0; | ||
| while (index < string.length) { | ||
| const codePoint = string.codePointAt(index); | ||
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| if (ESCAPES.has(codePoint)) { | ||
| const code = parseAnsiCode(string, index); | ||
| if (code) { | ||
| returnValue.push({ | ||
| type: 'ansi', | ||
| code, | ||
| endCode: getEndCode(code) | ||
| }); | ||
| index += code.length; | ||
| continue; | ||
| } | ||
| } | ||
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| const isFullWidth = isFullwidthCodePoint(codePoint); | ||
| const character = String.fromCodePoint(codePoint); | ||
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| returnValue.push({ | ||
| type: 'character', | ||
| value: character, | ||
| isFullWidth | ||
| }); | ||
| index += character.length; | ||
| visibleCount += isFullWidth ? 2 : character.length; | ||
| if (visibleCount >= endChar) { | ||
| break; | ||
| } | ||
| } | ||
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| return returnValue; | ||
| } | ||
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| function reduceAnsiCodes(codes) { | ||
| let returnValue = []; | ||
| for (const code of codes) { | ||
| if (code.code === ansiStyles.reset.open) { | ||
| // Reset code, disable all codes | ||
| returnValue = []; | ||
| } else if (endCodesSet.has(code.code)) { | ||
| // This is an end code, disable all matching start codes | ||
| returnValue = returnValue.filter(returnValueCode => returnValueCode.endCode !== code.code); | ||
| } else { | ||
| // This is a start code. Disable all styles this "overrides", then enable it | ||
| returnValue = returnValue.filter(returnValueCode => returnValueCode.endCode !== code.endCode); | ||
| returnValue.push(code); | ||
| } | ||
| } | ||
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| return returnValue; | ||
| } | ||
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| function undoAnsiCodes(codes) { | ||
| const reduced = reduceAnsiCodes(codes); | ||
| const endCodes = reduced.map(({endCode}) => endCode); | ||
| return endCodes.reverse().join(''); | ||
| } | ||
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| export default function sliceAnsi(string, begin, end) { | ||
| const tokens = tokenize(string, end); | ||
| let activeCodes = []; | ||
| let position = 0; | ||
| let returnValue = ''; | ||
| let include = false; | ||
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| for (const token of tokens) { | ||
| if (end !== undefined && position >= end) { | ||
| break; | ||
| } | ||
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| if (token.type === 'ansi') { | ||
| activeCodes.push(token); | ||
| if (include) { | ||
| returnValue += token.code; | ||
| } | ||
| } else { | ||
| // Char | ||
| if (!include && position >= begin) { | ||
| include = true; | ||
| // Simplify active codes | ||
| activeCodes = reduceAnsiCodes(activeCodes); | ||
| returnValue = activeCodes.map(({code}) => code).join(''); | ||
| } | ||
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| if (include) { | ||
| returnValue += token.value; | ||
| } | ||
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| position += token.isFullWidth ? 2 : token.value.length; | ||
| } | ||
| } | ||
|
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| // Disable active codes at the end | ||
| returnValue += undoAnsiCodes(activeCodes); | ||
| return returnValue; | ||
| } |
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after this change, the start codes get undone in the same order as in the input string.