Add a proper LocalColorSpaceCache class, rather than piggybacking on the image one (PR 12001 follow-up)

This will allow caching of ColorSpaces by either `Name` *or* `Ref`, which doesn't really make sense for images, thus allowing (better) caching for ColorSpaces used with e.g. Images and Patterns.

src/core/evaluator.js

@@ -73,13 +73,13 @@ import {
 } from "./standard_fonts.js";
 import { getTilingPatternIR, Pattern } from "./pattern.js";
 import { Lexer, Parser } from "./parser.js";
+import { LocalColorSpaceCache, LocalImageCache } from "./image_utils.js";
 import { bidi } from "./bidi.js";
 import { ColorSpace } from "./colorspace.js";
 import { DecodeStream } from "./stream.js";
 import { getGlyphsUnicode } from "./glyphlist.js";
 import { getMetrics } from "./metrics.js";
 import { isPDFFunction } from "./function.js";
-import { LocalImageCache } from "./image_utils.js";
 import { MurmurHash3_64 } from "./murmurhash3.js";
 import { OperatorList } from "./operator_list.js";
 import { PDFImage } from "./image.js";
@@ -1224,7 +1224,7 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
       var xref = this.xref;
       let parsingText = false;
       const localImageCache = new LocalImageCache();
-      const localColorSpaceCache = new LocalImageCache();
+      const localColorSpaceCache = new LocalColorSpaceCache();
 
       var xobjs = resources.get("XObject") || Dict.empty;
       var patterns = resources.get("Pattern") || Dict.empty;

src/core/image_utils.js

@@ -14,11 +14,14 @@
  */
 /* eslint no-var: error */
 
-import { assert, info, shadow } from "../shared/util.js";
+import { assert, info, shadow, unreachable } from "../shared/util.js";
 import { RefSetCache } from "./primitives.js";
 
-class LocalImageCache {
+class BaseLocalCache {
   constructor() {
+    if (this.constructor === BaseLocalCache) {
+      unreachable("Cannot initialize BaseLocalCache.");
+    }
     this._nameRefMap = new Map();
     this._imageMap = new Map();
     this._imageCache = new RefSetCache();
@@ -36,6 +39,12 @@ class LocalImageCache {
     return this._imageCache.get(ref) || null;
   }
 
+  set(name, ref, data) {
+    unreachable("Abstract method `set` called.");
+  }
+}
+
+class LocalImageCache extends BaseLocalCache {
   set(name, ref = null, data) {
     if (!name) {
       throw new Error('LocalImageCache.set - expected "name" argument.');
@@ -56,6 +65,32 @@ class LocalImageCache {
   }
 }
 
+class LocalColorSpaceCache extends BaseLocalCache {
+  set(name = null, ref = null, data) {
+    if (!name && !ref) {
+      throw new Error(
+        'LocalColorSpaceCache.set - expected "name" and/or "ref" argument.'
+      );
+    }
+    if (ref) {
+      if (this._imageCache.has(ref)) {
+        return;
+      }
+      if (name) {
+        // Optional when `ref` is defined.
+        this._nameRefMap.set(name, ref);
+      }
+      this._imageCache.put(ref, data);
+      return;
+    }
+    // name
+    if (this._imageMap.has(name)) {
+      return;
+    }
+    this._imageMap.set(name, data);
+  }
+}
+
 class GlobalImageCache {
   static get NUM_PAGES_THRESHOLD() {
     return shadow(this, "NUM_PAGES_THRESHOLD", 2);
@@ -149,4 +184,4 @@ class GlobalImageCache {
   }
 }
 
-export { LocalImageCache, GlobalImageCache };
+export { LocalImageCache, LocalColorSpaceCache, GlobalImageCache };