Store the Type1 program privateData in a Map, rather than an Object

This is nicer when checking if fields exist in `Type1Font.prototype.wrap`, and a couple of loops in that method are also "modernized" slightly.

src/core/type1_font.js

@@ -359,9 +359,8 @@ class Type1Font {
 
     const count = glyphs.length;
     const charsetArray = [".notdef"];
-    let i, ii;
-    for (i = 0; i < count; i++) {
-      const glyphName = charstrings[i].glyphName;
+    for (let i = 0; i < count; i++) {
+      const { glyphName } = charstrings[i];
       const index = CFFStandardStrings.indexOf(glyphName);
       if (index === -1) {
         strings.add(glyphName);
@@ -372,7 +371,7 @@ class Type1Font {
 
     const charStringsIndex = new CFFIndex();
     charStringsIndex.add([0x8b, 0x0e]); // .notdef
-    for (i = 0; i < count; i++) {
+    for (let i = 0; i < count; i++) {
       charStringsIndex.add(glyphs[i]);
     }
     cff.charStrings = charStringsIndex;
@@ -395,12 +394,11 @@ class Type1Font {
       "StdHW",
       "StdVW",
     ];
-    for (i = 0, ii = fields.length; i < ii; i++) {
-      const field = fields[i];
-      if (!(field in properties.privateData)) {
+    for (const field of fields) {
+      if (!properties.privateData.has(field)) {
         continue;
       }
-      const value = properties.privateData[field];
+      const value = properties.privateData.get(field);
       if (Array.isArray(value)) {
         // All of the private dictionary array data in CFF must be stored as
         // "delta-encoded" numbers.
@@ -413,8 +411,8 @@ class Type1Font {
     cff.topDict.privateDict = privateDict;
 
     const subrIndex = new CFFIndex();
-    for (i = 0, ii = subrs.length; i < ii; i++) {
-      subrIndex.add(subrs[i]);
+    for (const subr of subrs) {
+      subrIndex.add(subr);
     }
     privateDict.subrsIndex = subrIndex;
 

src/core/type1_parser.js

@@ -557,8 +557,7 @@ class Type1Parser {
 
     const subrs = [],
       charstrings = [];
-    const privateData = Object.create(null);
-    privateData.lenIV = 4;
+    const privateData = new Map([["lenIV", 4]]);
     const program = {
       subrs: [],
       charstrings: [],
@@ -593,7 +592,7 @@ class Type1Parser {
             length = this.readInt();
             this.getToken(); // read in 'RD' or '-|'
             data = length > 0 ? stream.getBytes(length) : new Uint8Array(0);
-            lenIV = program.properties.privateData.lenIV;
+            lenIV = privateData.get("lenIV");
             const encoded = this.readCharStrings(data, lenIV);
             this.nextChar();
             token = this.getToken(); // read in 'ND' or '|-'
@@ -618,7 +617,7 @@ class Type1Parser {
             length = this.readInt();
             this.getToken(); // read in 'RD' or '-|'
             data = length > 0 ? stream.getBytes(length) : new Uint8Array(0);
-            lenIV = program.properties.privateData.lenIV;
+            lenIV = privateData.get("lenIV");
             const encoded = this.readCharStrings(data, lenIV);
             this.nextChar();
             token = this.getToken(); // read in 'NP' or '|'
@@ -640,32 +639,32 @@ class Type1Parser {
             blueArray.length % 2 === 0 &&
             HINTING_ENABLED
           ) {
-            program.properties.privateData[token] = blueArray;
+            privateData.set(token, blueArray);
           }
           break;
         case "StemSnapH":
         case "StemSnapV":
-          program.properties.privateData[token] = this.readNumberArray();
+          privateData.set(token, this.readNumberArray());
           break;
         case "StdHW":
         case "StdVW":
-          program.properties.privateData[token] = this.readNumberArray()[0];
+          privateData.set(token, this.readNumberArray()[0]);
           break;
         case "BlueShift":
         case "lenIV":
         case "BlueFuzz":
         case "BlueScale":
         case "LanguageGroup":
-          program.properties.privateData[token] = this.readNumber();
+          privateData.set(token, this.readNumber());
           break;
         case "ExpansionFactor":
           // Firefox doesn't render correctly a font with a null factor on
           // Windows (see issue 15289), hence we just reset it to its default
           // value (0.06).
-          program.properties.privateData[token] = this.readNumber() || 0.06;
+          privateData.set(token, this.readNumber() || 0.06);
           break;
         case "ForceBold":
-          program.properties.privateData[token] = this.readBoolean();
+          privateData.set(token, this.readBoolean());
           break;
       }
     }

test/unit/type1_parser_spec.js

@@ -94,7 +94,7 @@ describe("Type1Parser", function () {
     const parser = new Type1Parser(stream, false, SEAC_ANALYSIS_ENABLED);
     const program = parser.extractFontProgram({});
     expect(program.charstrings.length).toEqual(1);
-    expect(program.properties.privateData.ExpansionFactor).toEqual(99);
+    expect(program.properties.privateData.get("ExpansionFactor")).toEqual(99);
   });
 
   it("parses font header font matrix", function () {