64 lines
2.0 KiB
TypeScript
64 lines
2.0 KiB
TypeScript
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/**
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* @license
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* Copyright Google Inc. All Rights Reserved.
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*
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* Use of this source code is governed by an MIT-style license that can be
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* found in the LICENSE file at https://angular.io/license
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*/
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const LF_CHAR = 10;
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const CR_CHAR = 13;
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const LINE_SEP_CHAR = 8232;
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const PARAGRAPH_CHAR = 8233;
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/** Gets the line and character for the given position from the line starts map. */
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export function getLineAndCharacterFromPosition(lineStartsMap: number[], position: number) {
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const lineIndex = findClosestLineStartPosition(lineStartsMap, position);
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return {character: position - lineStartsMap[lineIndex], line: lineIndex};
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}
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/**
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* Computes the line start map of the given text. This can be used in order to
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* retrieve the line and character of a given text position index.
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*/
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export function computeLineStartsMap(text: string): number[] {
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const result: number[] = [0];
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let pos = 0;
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while (pos < text.length) {
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const char = text.charCodeAt(pos++);
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// Handles the "CRLF" line break. In that case we peek the character
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// after the "CR" and check if it is a line feed.
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if (char === CR_CHAR) {
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if (text.charCodeAt(pos) === LF_CHAR) {
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pos++;
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}
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result.push(pos);
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} else if (char === LF_CHAR || char === LINE_SEP_CHAR || char === PARAGRAPH_CHAR) {
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result.push(pos);
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}
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}
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result.push(pos);
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return result;
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}
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/** Finds the closest line start for the given position. */
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function findClosestLineStartPosition<T>(
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linesMap: T[], position: T, low = 0, high = linesMap.length - 1) {
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while (low <= high) {
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const pivotIdx = Math.floor((low + high) / 2);
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const pivotEl = linesMap[pivotIdx];
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if (pivotEl === position) {
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return pivotIdx;
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} else if (position > pivotEl) {
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low = pivotIdx + 1;
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} else {
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high = pivotIdx - 1;
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}
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}
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// In case there was no exact match, return the closest "lower" line index. We also
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// subtract the index by one because want the index of the previous line start.
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return low - 1;
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}
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