292 lines
8.2 KiB
Plaintext
292 lines
8.2 KiB
Plaintext
/**
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* @typedef {import('unist').Node} Node
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* @typedef {import('unist').Parent} Parent
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*/
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/**
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* @template Fn
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* @template Fallback
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* @typedef {Fn extends (value: any) => value is infer Thing ? Thing : Fallback} Predicate
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*/
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/**
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* @callback Check
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* Check that an arbitrary value is a node.
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* @param {unknown} this
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* The given context.
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* @param {unknown} [node]
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* Anything (typically a node).
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* @param {number | null | undefined} [index]
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* The node’s position in its parent.
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* @param {Parent | null | undefined} [parent]
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* The node’s parent.
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* @returns {boolean}
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* Whether this is a node and passes a test.
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*
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* @typedef {Record<string, unknown> | Node} Props
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* Object to check for equivalence.
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*
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* Note: `Node` is included as it is common but is not indexable.
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*
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* @typedef {Array<Props | TestFunction | string> | Props | TestFunction | string | null | undefined} Test
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* Check for an arbitrary node.
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*
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* @callback TestFunction
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* Check if a node passes a test.
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* @param {unknown} this
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* The given context.
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* @param {Node} node
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* A node.
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* @param {number | undefined} [index]
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* The node’s position in its parent.
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* @param {Parent | undefined} [parent]
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* The node’s parent.
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* @returns {boolean | undefined | void}
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* Whether this node passes the test.
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*
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* Note: `void` is included until TS sees no return as `undefined`.
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*/
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/**
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* Check if `node` is a `Node` and whether it passes the given test.
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*
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* @param {unknown} node
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* Thing to check, typically `Node`.
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* @param {Test} test
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* A check for a specific node.
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* @param {number | null | undefined} index
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* The node’s position in its parent.
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* @param {Parent | null | undefined} parent
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* The node’s parent.
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* @param {unknown} context
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* Context object (`this`) to pass to `test` functions.
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* @returns {boolean}
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* Whether `node` is a node and passes a test.
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*/
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export const is =
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// Note: overloads in JSDoc can’t yet use different `@template`s.
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/**
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* @type {(
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* (<Condition extends string>(node: unknown, test: Condition, index?: number | null | undefined, parent?: Parent | null | undefined, context?: unknown) => node is Node & {type: Condition}) &
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* (<Condition extends Props>(node: unknown, test: Condition, index?: number | null | undefined, parent?: Parent | null | undefined, context?: unknown) => node is Node & Condition) &
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* (<Condition extends TestFunction>(node: unknown, test: Condition, index?: number | null | undefined, parent?: Parent | null | undefined, context?: unknown) => node is Node & Predicate<Condition, Node>) &
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* ((node?: null | undefined) => false) &
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* ((node: unknown, test?: null | undefined, index?: number | null | undefined, parent?: Parent | null | undefined, context?: unknown) => node is Node) &
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* ((node: unknown, test?: Test, index?: number | null | undefined, parent?: Parent | null | undefined, context?: unknown) => boolean)
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* )}
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*/
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(
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/**
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* @param {unknown} [node]
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* @param {Test} [test]
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* @param {number | null | undefined} [index]
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* @param {Parent | null | undefined} [parent]
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* @param {unknown} [context]
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* @returns {boolean}
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*/
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// eslint-disable-next-line max-params
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function (node, test, index, parent, context) {
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const check = convert(test)
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if (
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index !== undefined &&
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index !== null &&
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(typeof index !== 'number' ||
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index < 0 ||
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index === Number.POSITIVE_INFINITY)
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) {
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throw new Error('Expected positive finite index')
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}
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if (
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parent !== undefined &&
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parent !== null &&
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(!is(parent) || !parent.children)
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) {
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throw new Error('Expected parent node')
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}
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if (
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(parent === undefined || parent === null) !==
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(index === undefined || index === null)
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) {
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throw new Error('Expected both parent and index')
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}
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return looksLikeANode(node)
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? check.call(context, node, index, parent)
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: false
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}
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)
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/**
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* Generate an assertion from a test.
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*
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* Useful if you’re going to test many nodes, for example when creating a
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* utility where something else passes a compatible test.
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*
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* The created function is a bit faster because it expects valid input only:
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* a `node`, `index`, and `parent`.
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*
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* @param {Test} test
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* * when nullish, checks if `node` is a `Node`.
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* * when `string`, works like passing `(node) => node.type === test`.
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* * when `function` checks if function passed the node is true.
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* * when `object`, checks that all keys in test are in node, and that they have (strictly) equal values.
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* * when `array`, checks if any one of the subtests pass.
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* @returns {Check}
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* An assertion.
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*/
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export const convert =
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// Note: overloads in JSDoc can’t yet use different `@template`s.
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/**
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* @type {(
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* (<Condition extends string>(test: Condition) => (node: unknown, index?: number | null | undefined, parent?: Parent | null | undefined, context?: unknown) => node is Node & {type: Condition}) &
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* (<Condition extends Props>(test: Condition) => (node: unknown, index?: number | null | undefined, parent?: Parent | null | undefined, context?: unknown) => node is Node & Condition) &
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* (<Condition extends TestFunction>(test: Condition) => (node: unknown, index?: number | null | undefined, parent?: Parent | null | undefined, context?: unknown) => node is Node & Predicate<Condition, Node>) &
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* ((test?: null | undefined) => (node?: unknown, index?: number | null | undefined, parent?: Parent | null | undefined, context?: unknown) => node is Node) &
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* ((test?: Test) => Check)
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* )}
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*/
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(
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/**
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* @param {Test} [test]
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* @returns {Check}
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*/
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function (test) {
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if (test === null || test === undefined) {
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return ok
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}
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if (typeof test === 'function') {
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return castFactory(test)
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}
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if (typeof test === 'object') {
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return Array.isArray(test) ? anyFactory(test) : propsFactory(test)
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}
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if (typeof test === 'string') {
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return typeFactory(test)
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}
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throw new Error('Expected function, string, or object as test')
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}
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)
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/**
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* @param {Array<Props | TestFunction | string>} tests
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* @returns {Check}
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*/
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function anyFactory(tests) {
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/** @type {Array<Check>} */
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const checks = []
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let index = -1
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while (++index < tests.length) {
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checks[index] = convert(tests[index])
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}
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return castFactory(any)
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/**
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* @this {unknown}
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* @type {TestFunction}
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*/
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function any(...parameters) {
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let index = -1
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while (++index < checks.length) {
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if (checks[index].apply(this, parameters)) return true
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}
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return false
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}
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}
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/**
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* Turn an object into a test for a node with a certain fields.
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*
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* @param {Props} check
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* @returns {Check}
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*/
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function propsFactory(check) {
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const checkAsRecord = /** @type {Record<string, unknown>} */ (check)
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return castFactory(all)
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/**
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* @param {Node} node
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* @returns {boolean}
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*/
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function all(node) {
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const nodeAsRecord = /** @type {Record<string, unknown>} */ (
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/** @type {unknown} */ (node)
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)
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/** @type {string} */
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let key
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for (key in check) {
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if (nodeAsRecord[key] !== checkAsRecord[key]) return false
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}
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return true
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}
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}
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/**
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* Turn a string into a test for a node with a certain type.
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*
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* @param {string} check
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* @returns {Check}
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*/
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function typeFactory(check) {
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return castFactory(type)
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/**
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* @param {Node} node
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*/
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function type(node) {
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return node && node.type === check
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}
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}
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/**
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* Turn a custom test into a test for a node that passes that test.
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*
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* @param {TestFunction} testFunction
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* @returns {Check}
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*/
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function castFactory(testFunction) {
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return check
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/**
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* @this {unknown}
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* @type {Check}
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*/
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function check(value, index, parent) {
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return Boolean(
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looksLikeANode(value) &&
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testFunction.call(
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this,
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value,
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typeof index === 'number' ? index : undefined,
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parent || undefined
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)
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)
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}
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}
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function ok() {
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return true
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}
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/**
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* @param {unknown} value
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* @returns {value is Node}
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*/
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function looksLikeANode(value) {
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return value !== null && typeof value === 'object' && 'type' in value
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}
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