From 729bdbe347c7c250ef4e6d97b7dca718d07a3152 Mon Sep 17 00:00:00 2001
From: Bogdan Chadkin <trysound@yandex.ru>
Date: Thu, 2 Sep 2021 02:17:56 +0300
Subject: [PATCH] Refactor cleanupIDs

I still did get how id generation works but data flow is clear now at
least.

- covered with types
- migrated to visitor plugin api
- got rid of traverse api
---
 plugins/cleanupIDs.js | 503 ++++++++++++++++++++++--------------------
 tsconfig.json         |   1 -
 2 files changed, 261 insertions(+), 243 deletions(-)

diff --git a/plugins/cleanupIDs.js b/plugins/cleanupIDs.js
index b47e5a79e..45bfe2812 100644
--- a/plugins/cleanupIDs.js
+++ b/plugins/cleanupIDs.js
@@ -1,259 +1,103 @@
 'use strict';
 
-const { traverse, traverseBreak } = require('../lib/xast.js');
-const { parseName } = require('../lib/svgo/tools.js');
-
-exports.name = 'cleanupIDs';
+/**
+ * @typedef {import('../lib/types').XastElement} XastElement
+ */
 
-exports.type = 'full';
+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';
 
-exports.params = {
-  remove: true,
-  minify: true,
-  prefix: '',
-  preserve: [],
-  preservePrefixes: [],
-  force: false,
-};
-
-var referencesProps = new Set(require('./_collections').referencesProps),
-  regReferencesUrl = /\burl\(("|')?#(.+?)\1\)/,
-  regReferencesHref = /^#(.+?)$/,
-  regReferencesBegin = /(\w+)\./,
-  styleOrScript = ['style', 'script'],
-  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',
-  ],
-  maxIDindex = generateIDchars.length - 1;
+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;
 
 /**
- * Remove unused and minify used IDs
- * (only if there are no any <style> or <script>).
- *
- * @param {Object} item current iteration item
- * @param {Object} params plugin params
+ * Check if an ID starts with any one of a list of strings.
  *
- * @author Kir Belevich
+ * @type {(string: string, prefixes: Array<string>) => boolean}
  */
-exports.fn = function (root, params) {
-  var currentID,
-    currentIDstring,
-    IDs = new Map(),
-    referencesIDs = new Map(),
-    hasStyleOrScript = false,
-    preserveIDs = new Set(
-      Array.isArray(params.preserve)
-        ? params.preserve
-        : params.preserve
-        ? [params.preserve]
-        : []
-    ),
-    preserveIDPrefixes = new Set(
-      Array.isArray(params.preservePrefixes)
-        ? params.preservePrefixes
-        : params.preservePrefixes
-        ? [params.preservePrefixes]
-        : []
-    ),
-    idValuePrefix = '#',
-    idValuePostfix = '.';
-
-  traverse(root, (node) => {
-    if (hasStyleOrScript === true) {
-      return traverseBreak;
-    }
-
-    // quit if <style> or <script> present ('force' param prevents quitting)
-    if (!params.force) {
-      if (node.isElem(styleOrScript) && node.children.length !== 0) {
-        hasStyleOrScript = true;
-        return;
-      }
-
-      // Don't remove IDs if the whole SVG consists only of defs.
-      if (node.type === 'element' && 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 traverseBreak;
-        }
-      }
-    }
-
-    // …and don't remove any ID if yes
-    if (node.type === 'element') {
-      for (const [name, value] of Object.entries(node.attributes)) {
-        let key;
-        let match;
-
-        // save IDs
-        if (name === 'id') {
-          key = value;
-          if (IDs.has(key)) {
-            delete node.attributes.id; // remove repeated id
-          } else {
-            IDs.set(key, node);
-          }
-        } else {
-          // save references
-          const { local } = parseName(name);
-          if (
-            referencesProps.has(name) &&
-            (match = value.match(regReferencesUrl))
-          ) {
-            key = match[2]; // url() reference
-          } else if (
-            (local === 'href' && (match = value.match(regReferencesHref))) ||
-            (name === 'begin' && (match = value.match(regReferencesBegin)))
-          ) {
-            key = match[1]; // href reference
-          }
-          if (key) {
-            const refs = referencesIDs.get(key) || [];
-            refs.push({ element: node, name, value });
-            referencesIDs.set(key, refs);
-          }
-        }
-      }
-    }
-  });
-
-  if (hasStyleOrScript) {
-    return root;
-  }
-
-  const idPreserved = (id) =>
-    preserveIDs.has(id) || idMatchesPrefix(preserveIDPrefixes, id);
-
-  for (const [key, refs] of referencesIDs) {
-    if (IDs.has(key)) {
-      // replace referenced IDs with the minified ones
-      if (params.minify && !idPreserved(key)) {
-        do {
-          currentIDstring = getIDstring(
-            (currentID = generateID(currentID)),
-            params
-          );
-        } while (idPreserved(currentIDstring));
-
-        IDs.get(key).attributes.id = currentIDstring;
-
-        for (const { element, name, value } of refs) {
-          element.attributes[name] = value.includes(idValuePrefix)
-            ? value.replace(
-                idValuePrefix + key,
-                idValuePrefix + currentIDstring
-              )
-            : value.replace(
-                key + idValuePostfix,
-                currentIDstring + idValuePostfix
-              );
-        }
-      }
-      // don't remove referenced IDs
-      IDs.delete(key);
+const hasStringPrefix = (string, prefixes) => {
+  for (const prefix of prefixes) {
+    if (string.startsWith(prefix)) {
+      return true;
     }
   }
-  // remove non-referenced IDs attributes from elements
-  if (params.remove) {
-    for (var keyElem of IDs) {
-      if (!idPreserved(keyElem[0])) {
-        delete keyElem[1].attributes.id;
-      }
-    }
-  }
-  return root;
-};
-
-/**
- * Check if an ID starts with any one of a list of strings.
- *
- * @param {Array} of prefix strings
- * @param {String} current ID
- * @return {Boolean} if currentID starts with one of the strings in prefixArray
- */
-function idMatchesPrefix(prefixArray, currentID) {
-  if (!currentID) return false;
-
-  for (var prefix of prefixArray) if (currentID.startsWith(prefix)) return true;
   return false;
-}
+};
 
 /**
  * Generate unique minimal ID.
  *
- * @param {Array} [currentID] current ID
- * @return {Array} generated ID array
+ * @type {(currentID: null | Array<number>) => Array<number>}
  */
-function generateID(currentID) {
-  if (!currentID) return [0];
-
-  currentID[currentID.length - 1]++;
-
-  for (var i = currentID.length - 1; i > 0; i--) {
+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]++;
       }
@@ -264,15 +108,190 @@ function generateID(currentID) {
     currentID.unshift(0);
   }
   return currentID;
-}
+};
 
 /**
  * Get string from generated ID array.
  *
- * @param {Array} arr input ID array
- * @return {String} output ID string
+ * @type {(arr: Array<number>, prefix: string) => string}
  */
-function getIDstring(arr, params) {
-  var str = params.prefix;
-  return str + arr.map((i) => generateIDchars[i]).join('');
-}
+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;
+            }
+          }
+        }
+      },
+    },
+  };
+};
diff --git a/tsconfig.json b/tsconfig.json
index b93c989c7..f4841c8c1 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -13,7 +13,6 @@
   "include": ["plugins/**/*", "lib/xast.test.js", "lib/path.test.js"],
   "exclude": [
     "plugins/_applyTransforms.js",
-    "plugins/cleanupIDs.js",
     "plugins/collapseGroups.js",
     "plugins/convertPathData.js",
     "plugins/convertStyleToAttrs.js",