forked from Fediversity/fediversity.eu
73 lines
2.2 KiB
JavaScript
73 lines
2.2 KiB
JavaScript
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import { isScalar, isCollection } from '../nodes/identity.js';
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import { visit } from '../visit.js';
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/**
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* Verify that the input string is a valid anchor.
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*
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* Will throw on errors.
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*/
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function anchorIsValid(anchor) {
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if (/[\x00-\x19\s,[\]{}]/.test(anchor)) {
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const sa = JSON.stringify(anchor);
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const msg = `Anchor must not contain whitespace or control characters: ${sa}`;
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throw new Error(msg);
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}
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return true;
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}
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function anchorNames(root) {
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const anchors = new Set();
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visit(root, {
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Value(_key, node) {
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if (node.anchor)
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anchors.add(node.anchor);
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}
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});
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return anchors;
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}
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/** Find a new anchor name with the given `prefix` and a one-indexed suffix. */
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function findNewAnchor(prefix, exclude) {
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for (let i = 1; true; ++i) {
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const name = `${prefix}${i}`;
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if (!exclude.has(name))
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return name;
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}
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}
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function createNodeAnchors(doc, prefix) {
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const aliasObjects = [];
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const sourceObjects = new Map();
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let prevAnchors = null;
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return {
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onAnchor: (source) => {
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aliasObjects.push(source);
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if (!prevAnchors)
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prevAnchors = anchorNames(doc);
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const anchor = findNewAnchor(prefix, prevAnchors);
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prevAnchors.add(anchor);
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return anchor;
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},
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/**
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* With circular references, the source node is only resolved after all
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* of its child nodes are. This is why anchors are set only after all of
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* the nodes have been created.
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*/
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setAnchors: () => {
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for (const source of aliasObjects) {
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const ref = sourceObjects.get(source);
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if (typeof ref === 'object' &&
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ref.anchor &&
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(isScalar(ref.node) || isCollection(ref.node))) {
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ref.node.anchor = ref.anchor;
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}
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else {
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const error = new Error('Failed to resolve repeated object (this should not happen)');
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error.source = source;
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throw error;
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}
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}
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},
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sourceObjects
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};
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}
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export { anchorIsValid, anchorNames, createNodeAnchors, findNewAnchor };
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