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'use strict';
/** * @typedef {import('../lib/types').XastElement} XastElement */
const { visitSkip } = require('../lib/xast.js'); const { referencesProps } = require('./_collections.js');
exports.type = 'visitor'; exports.name = 'cleanupIDs'; exports.active = true; exports.description = 'removes unused IDs and minifies used';
const regReferencesUrl = /\burl\(("|')?#(.+?)\1\)/; const regReferencesHref = /^#(.+?)$/; const regReferencesBegin = /(\w+)\./; const generateIDchars = [ 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', ]; const maxIDindex = generateIDchars.length - 1;
/** * Check if an ID starts with any one of a list of strings. * * @type {(string: string, prefixes: Array<string>) => boolean} */ const hasStringPrefix = (string, prefixes) => { for (const prefix of prefixes) { if (string.startsWith(prefix)) { return true; } } return false; };
/** * Generate unique minimal ID. * * @type {(currentID: null | Array<number>) => Array<number>} */ const generateID = (currentID) => { if (currentID == null) { return [0]; } currentID[currentID.length - 1] += 1; for (let i = currentID.length - 1; i > 0; i--) { if (currentID[i] > maxIDindex) { currentID[i] = 0; if (currentID[i - 1] !== undefined) { currentID[i - 1]++; } } } if (currentID[0] > maxIDindex) { currentID[0] = 0; currentID.unshift(0); } return currentID; };
/** * Get string from generated ID array. * * @type {(arr: Array<number>, prefix: string) => string} */ const getIDstring = (arr, prefix) => { return prefix + arr.map((i) => generateIDchars[i]).join(''); };
/** * Remove unused and minify used IDs * (only if there are no any <style> or <script>). * * @author Kir Belevich * * @type {import('../lib/types').Plugin<{ * remove?: boolean, * minify?: boolean, * prefix?: string, * preserve?: Array<string>, * preservePrefixes?: Array<string>, * force?: boolean, * }>} */ exports.fn = (_root, params) => { const { remove = true, minify = true, prefix = '', preserve = [], preservePrefixes = [], force = false, } = params; const preserveIDs = new Set( Array.isArray(preserve) ? preserve : preserve ? [preserve] : [] ); const preserveIDPrefixes = Array.isArray(preservePrefixes) ? preservePrefixes : preservePrefixes ? [preservePrefixes] : []; /** * @type {Map<string, XastElement>} */ const nodeById = new Map(); /** * @type {Map<string, Array<{element: XastElement, name: string, value: string }>>} */ const referencesById = new Map(); let deoptimized = false;
return { element: { enter: (node) => { if (force == false) { // deoptimize if style or script elements are present
if ( (node.name === 'style' || node.name === 'script') && node.children.length !== 0 ) { deoptimized = true; return; }
// avoid removing IDs if the whole SVG consists only of defs
if (node.name === 'svg') { let hasDefsOnly = true; for (const child of node.children) { if (child.type !== 'element' || child.name !== 'defs') { hasDefsOnly = false; break; } } if (hasDefsOnly) { return visitSkip; } } }
for (const [name, value] of Object.entries(node.attributes)) { if (name === 'id') { // collect all ids
const id = value; if (nodeById.has(id)) { delete node.attributes.id; // remove repeated id
} else { nodeById.set(id, node); } } else { // collect all references
/** * @type {null | string} */ let id = null; if (referencesProps.includes(name)) { const match = value.match(regReferencesUrl); if (match != null) { id = match[2]; // url() reference
} } if (name === 'href' || name.endsWith(':href')) { const match = value.match(regReferencesHref); if (match != null) { id = match[1]; // href reference
} } if (name === 'begin') { const match = value.match(regReferencesBegin); if (match != null) { id = match[1]; // href reference
} } if (id != null) { let refs = referencesById.get(id); if (refs == null) { refs = []; referencesById.set(id, refs); } refs.push({ element: node, name, value }); } } } }, },
root: { exit: () => { if (deoptimized) { return; } /** * @type {(id: string) => boolean} **/ const isIdPreserved = (id) => preserveIDs.has(id) || hasStringPrefix(id, preserveIDPrefixes); /** * @type {null | Array<number>} */ let currentID = null; for (const [id, refs] of referencesById) { const node = nodeById.get(id); if (node != null) { // replace referenced IDs with the minified ones
if (minify && isIdPreserved(id) === false) { /** * @type {null | string} */ let currentIDString = null; do { currentID = generateID(currentID); currentIDString = getIDstring(currentID, prefix); } while (isIdPreserved(currentIDString)); node.attributes.id = currentIDString; for (const { element, name, value } of refs) { if (value.includes('#')) { // replace id in href and url()
element.attributes[name] = value.replace( `#${id}`, `#${currentIDString}` ); } else { // replace id in begin attribute
element.attributes[name] = value.replace( `${id}.`, `${currentIDString}.` ); } } } // keep referenced node
nodeById.delete(id); } } // remove non-referenced IDs attributes from elements
if (remove) { for (const [id, node] of nodeById) { if (isIdPreserved(id) === false) { delete node.attributes.id; } } } }, }, }; };
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