122 lines
3.1 KiB
JavaScript
122 lines
3.1 KiB
JavaScript
/**
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* @typedef {import('vfile').VFile} VFile
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* @typedef {import('vfile').Value} Value
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* @typedef {import('unist').Point} UnistPoint
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*/
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/**
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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 the line/column based `Point` for `offset` in the bound indices.
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*
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* Returns `undefined` when given out of bounds input.
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*
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* Also implemented in Rust in [`wooorm/markdown-rs`][markdown-rs].
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*
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* [markdown-rs]: https://github.com/wooorm/markdown-rs/blob/main/src/util/location.rs
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* @param {number | null | undefined} [offset]
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* Something that should be an `offset.
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* @returns {UnistPoint | undefined}
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* Point, if `offset` is valid and in-bounds input.
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*
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* @callback ToOffset
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* Get the `offset` from a line/column based `Point` in the bound indices.
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* @param {PointLike | null | undefined} [point]
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* Something that should be a `point.
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* @returns {number | undefined}
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* Offset (`number`) or `undefined` 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 the line/column based `Point` for `offset` in the bound indices.
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* @property {ToOffset} toOffset
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* Get the `offset` from a line/column based `Point` in the bound indices.
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*/
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const search = /\r?\n|\r/g
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/**
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* Create an index of the given document to translate between line/column and
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* offset based positional info.
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*
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* Also implemented in Rust in [`wooorm/markdown-rs`][markdown-rs].
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*
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* [markdown-rs]: https://github.com/wooorm/markdown-rs/blob/main/src/util/location.rs
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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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/**
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* List, where each index is a line number (0-based), and each value is the
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* byte index *after* where the line ends.
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*
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* @type {Array<number>}
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*/
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const indices = []
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search.lastIndex = 0
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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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}
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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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}
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}
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