115 lines
2.8 KiB
JavaScript
115 lines
2.8 KiB
JavaScript
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/**
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* @typedef {import('vfile').VFile} VFile
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* @typedef {import('vfile').Value} Value
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*/
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/**
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* @typedef Point
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* unist point, where `line` and `column` can be `undefined`.
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* @property {number | undefined} line
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* Line.
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* @property {number | undefined} column
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* Column.
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* @property {number | undefined} [offset]
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* Offset.
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*
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* @typedef PointLike
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* unist point, allowed as input.
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* @property {number | null | undefined} [line]
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* Line.
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* @property {number | null | undefined} [column]
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* Column.
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* @property {number | null | undefined} [offset]
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* Offset.
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*
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* @callback ToPoint
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* Get a line/column-based `point` from `offset`.
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* @param {number | null | undefined} [offset]
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* Something that should be an `offset.
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* @returns {Point}
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* Point, line/column are undefined for invalid or out of bounds input.
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*
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* @callback ToOffset
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* Get an offset from a line/column-based `point`.
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* @param {Point | null | undefined} [point]
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* Something that should be a `point.
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* @returns {number}
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* Offset or `-1` for invalid or out of bounds input.
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*
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* @typedef Location
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* Accessors for index.
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* @property {ToPoint} toPoint
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* Get a line/column-based `point` from `offset`.
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* @property {ToOffset} toOffset
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* Get an offset from a line/column-based `point`.
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*/
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/**
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* Index the given document so you can translate between line/column and offset
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* based positional info.
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*
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* @param {VFile | Value} file
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* File to index.
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* @returns {Location}
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* Accessors for index.
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*/
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export function location(file) {
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const value = String(file)
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/** @type {Array<number>} */
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const indices = []
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const search = /\r?\n|\r/g
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while (search.test(value)) {
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indices.push(search.lastIndex)
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}
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indices.push(value.length + 1)
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return {toPoint, toOffset}
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/** @type {ToPoint} */
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function toPoint(offset) {
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let index = -1
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if (
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typeof offset === 'number' &&
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offset > -1 &&
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offset < indices[indices.length - 1]
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) {
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while (++index < indices.length) {
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if (indices[index] > offset) {
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return {
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line: index + 1,
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column: offset - (index > 0 ? indices[index - 1] : 0) + 1,
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offset
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}
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}
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}
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}
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return {line: undefined, column: undefined, offset: undefined}
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}
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/** @type {ToOffset} */
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function toOffset(point) {
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const line = point && point.line
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const column = point && point.column
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if (
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typeof line === 'number' &&
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typeof column === 'number' &&
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!Number.isNaN(line) &&
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!Number.isNaN(column) &&
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line - 1 in indices
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) {
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const offset = (indices[line - 2] || 0) + column - 1 || 0
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if (offset > -1 && offset < indices[indices.length - 1]) {
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return offset
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}
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}
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return -1
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}
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}
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