[Pkg-javascript-commits] [pdf.js] 11/109: cmaps: Use cmap.forEach instead of Array.forEach

[David Prévot]

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commit b0a8c0fa400d6e236c16f0c733eb0324d38e430f
Author: Rob Wu <rob at robwu.nl>
Date:   Sat Aug 8 01:16:05 2015 +0200

    cmaps: Use cmap.forEach instead of Array.forEach
    
    CMaps may be sparse. Array.prototype.forEach is terribly slow in Chrome
    (and also in Firefox) when the sparse array contains a key with a high
    value. E.g.
    
        console.time('forEach sparse')
        var a = [];
        a[0xFFFFFF] = 1;
        a.forEach(function(){});
        console.timeEnd('forEach sparse');
    
        // Chrome: 2890ms
        // Firefox: 1345ms
    
    Switching to CMap.prototype.forEach, which is optimized for such
    scenarios fixes the problem.
---
 src/core/evaluator.js | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/core/evaluator.js b/src/core/evaluator.js
index ed137f8..9eb9c63 100644
--- a/src/core/evaluator.js
+++ b/src/core/evaluator.js
@@ -1370,11 +1370,11 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
         if (cmap instanceof IdentityCMap) {
           return new IdentityToUnicodeMap(0, 0xFFFF);
         }
-        cmap = cmap.getMap();
+        var map = [];
         // Convert UTF-16BE
         // NOTE: cmap can be a sparse array, so use forEach instead of for(;;)
         // to iterate over all keys.
-        cmap.forEach(function(token, i) {
+        cmap.forEach(function(charCode, token) {
           var str = [];
           for (var k = 0; k < token.length; k += 2) {
             var w1 = (token.charCodeAt(k) << 8) | token.charCodeAt(k + 1);
@@ -1386,9 +1386,9 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
             var w2 = (token.charCodeAt(k) << 8) | token.charCodeAt(k + 1);
             str.push(((w1 & 0x3ff) << 10) + (w2 & 0x3ff) + 0x10000);
           }
-          cmap[i] = String.fromCharCode.apply(String, str);
+          map[charCode] = String.fromCharCode.apply(String, str);
         });
-        return new ToUnicodeMap(cmap);
+        return new ToUnicodeMap(map);
       }
       return null;
     },

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