Optimization: Add syntax check cache

index.js

@@ -19,6 +19,7 @@ var isarray = require('isarray');
 var defined = require('defined');
 var has = require('has');
 var sanitize = require('htmlescape').sanitize;
+var shasum = require('shasum');
 
 var bresolve = require('browser-resolve');
 var resolve = require('resolve');
@@ -68,6 +69,7 @@ function Browserify (files, opts) {
         }
         : bresolve
     ;
+    self._syntaxCache = {};
 
     var ignoreTransform = [].concat(opts.ignoreTransform).filter(Boolean);
     self._filterTransform = function (tr) {
@@ -623,9 +625,14 @@ Browserify.prototype._unshebang = function () {
 };
 
 Browserify.prototype._syntax = function () {
+    var self = this;
     return through.obj(function (row, enc, next) {
-        var err = syntaxError(row.source, row.file || row.id);
-        if (err) return this.emit('error', err);
+        var h = shasum(row.source);
+        if (typeof self._syntaxCache[h] === 'undefined') {
+            var err = syntaxError(row.source, row.file || row.id);
+            if (err) return this.emit('error', err);
+            self._syntaxCache[h] = true;
+        }
         this.push(row);
         next();
     });

test/syntax_cache.js

@@ -0,0 +1,47 @@
+var Seq = require('seq');
+var browserify = require('../');
+var test = require('tap').test;
+var shasum = require('shasum');
+
+test('syntax cache - valid', function (t) {
+    t.plan(2);
+
+    var expectedCache = {}
+    var cacheKey;
+
+    var b = browserify(__dirname + '/syntax_cache/valid.js');    
+    b.once('dep', function(row) {
+        cacheKey = shasum(row.source);
+        expectedCache[cacheKey] = true;
+    });
+
+    Seq()
+        .seq(function() { b.bundle(this); })
+        .seq(function() {
+            t.deepEqual(b._syntaxCache, expectedCache);
+            b._syntaxCache[cacheKey] = expectedCache[cacheKey] = 'beep';
+            b.bundle(function(err, src) {
+                // if the cache worked, the "cacheKey"
+                // should not be reset to "true"
+                t.deepEqual(b._syntaxCache, expectedCache);
+            });
+        });
+});
+
+test('syntax cache - skip invalid', function (t) {
+    t.plan(5);
+
+    var b = browserify(__dirname + '/syntax_cache/invalid.js');
+
+    Seq()
+        .seq(function() { b.bundle(this); })
+        .catch(function(lastErr) {
+            t.deepEqual(b._syntaxCache, {});
+            t.similar(String(lastErr), /ParseError/);
+            b.bundle(function(err, src) {
+                t.deepEqual(b._syntaxCache, {});
+                t.similar(String(err), /ParseError/);
+                t.notEqual(lastErr, err, 'errors should be unique');
+            });
+        });
+});

test/syntax_cache/invalid.js

@@ -0,0 +1,2 @@
+var x = {
+var y = 6;

test/syntax_cache/valid.js

@@ -0,0 +1,2 @@
+var x = {};
+var y = 6;