2020-04-06 09:26:58 -07:00

58 lines
1.7 KiB
TypeScript

/**
* @license
* Copyright Google Inc. 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
*/
/**
* A marker that indicates the start of a segment in a mapping.
*
* The end of a segment is indicated by the the first segment-marker of another mapping whose start
* is greater or equal to this one.
*/
export interface SegmentMarker {
readonly line: number;
readonly column: number;
readonly position: number;
next: SegmentMarker|undefined;
}
/**
* Compare two segment-markers, for use in a search or sorting algorithm.
*
* @returns a positive number if `a` is after `b`, a negative number if `b` is after `a`
* and zero if they are at the same position.
*/
export function compareSegments(a: SegmentMarker, b: SegmentMarker): number {
return a.position - b.position;
}
/**
* Return a new segment-marker that is offset by the given number of characters.
*
* @param startOfLinePositions the position of the start of each line of content of the source file
* whose segment-marker we are offsetting.
* @param marker the segment to offset.
* @param offset the number of character to offset by.
*/
export function offsetSegment(
startOfLinePositions: number[], marker: SegmentMarker, offset: number): SegmentMarker {
if (offset === 0) {
return marker;
}
let line = marker.line;
const position = marker.position + offset;
while (line < startOfLinePositions.length - 1 && startOfLinePositions[line + 1] <= position) {
line++;
}
while (line > 0 && startOfLinePositions[line] > position) {
line--;
}
const column = position - startOfLinePositions[line];
return {line, column, position, next: undefined};
}