angular-cn/packages/core/schematics/utils/line_mappings.ts

64 lines
2.0 KiB
TypeScript

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