anchors.js•2.29 kB
import { isScalar, isCollection } from '../nodes/identity.js';
import { visit } from '../visit.js';
/**
* Verify that the input string is a valid anchor.
*
* Will throw on errors.
*/
function anchorIsValid(anchor) {
if (/[\x00-\x19\s,[\]{}]/.test(anchor)) {
const sa = JSON.stringify(anchor);
const msg = `Anchor must not contain whitespace or control characters: ${sa}`;
throw new Error(msg);
}
return true;
}
function anchorNames(root) {
const anchors = new Set();
visit(root, {
Value(_key, node) {
if (node.anchor)
anchors.add(node.anchor);
}
});
return anchors;
}
/** Find a new anchor name with the given `prefix` and a one-indexed suffix. */
function findNewAnchor(prefix, exclude) {
for (let i = 1; true; ++i) {
const name = `${prefix}${i}`;
if (!exclude.has(name))
return name;
}
}
function createNodeAnchors(doc, prefix) {
const aliasObjects = [];
const sourceObjects = new Map();
let prevAnchors = null;
return {
onAnchor: (source) => {
aliasObjects.push(source);
if (!prevAnchors)
prevAnchors = anchorNames(doc);
const anchor = findNewAnchor(prefix, prevAnchors);
prevAnchors.add(anchor);
return anchor;
},
/**
* With circular references, the source node is only resolved after all
* of its child nodes are. This is why anchors are set only after all of
* the nodes have been created.
*/
setAnchors: () => {
for (const source of aliasObjects) {
const ref = sourceObjects.get(source);
if (typeof ref === 'object' &&
ref.anchor &&
(isScalar(ref.node) || isCollection(ref.node))) {
ref.node.anchor = ref.anchor;
}
else {
const error = new Error('Failed to resolve repeated object (this should not happen)');
error.source = source;
throw error;
}
}
},
sourceObjects
};
}
export { anchorIsValid, anchorNames, createNodeAnchors, findNewAnchor };