--js-transform option for emcc

emcc

@@ -138,6 +138,20 @@ Options that are modified or new in %s include:
                               generated code!
   --closure <on>           0: No closure compiler (default in -O0, -O1)
                            1: Run closure compiler (default in -O2, -O3)
+  --js-transform <cmd>     <cmd> will be called on the generated code
+                           before it is optimized. This lets you modify
+                           the JavaScript, for example adding some code
+                           or removing some code, in a way that those
+                           modifications will be optimized together with
+                           the generated code properly. <cmd> will be
+                           called with the filename of the generated
+                           code as a parameter; to modify the code, you
+                           can read the original data and then append to
+                           it or overwrite it with the modified data.
+                           <cmd> is interpreted as a space-separated
+                           list of arguments, for example, <cmd> of
+                           "python processor.py" will cause a python
+                           script to be run.
 
 The target file, if specified (-o <target>), defines what will
 be generated:
@@ -254,6 +268,7 @@ try:
   opt_level = 0
   llvm_opt_level = None
   closure = None
+  js_transform = None
 
   def check_bad_eq(arg):
     assert '=' not in arg, 'Invalid parameter (do not use "=" with "--" options)'
@@ -277,6 +292,11 @@ try:
       closure = int(newargs[i+1])
       newargs[i] = ''
       newargs[i+1] = ''
+    elif newargs[i].startswith('--js-transform'):
+      check_bad_eq(newargs[i])
+      js_transform = newargs[i+1]
+      newargs[i] = ''
+      newargs[i+1] = ''
     elif newargs[i] == '-MF': # clang cannot handle this, so we fake it
       f = open(newargs[i+1], 'w')
       f.write('\n')
@@ -478,12 +498,11 @@ try:
   if DEBUG: save_intermediate('original')
 
   # Apply a source code transformation, if requested
-  source_transform = os.environ.get('EMCC_JS_PROCESSOR')
-  if source_transform:
-    exec source_transform in locals()
+  if js_transform:
     shutil.copyfile(final, final + '.tr.js')
     final += '.tr.js'
-    process(final)
+    if DEBUG: print >> sys.stderr, 'emcc: applying transform: %s' % js_transform
+    Popen(js_transform.split(' ') + [os.path.abspath(final)]).communicate()
     if DEBUG: save_intermediate('transformed')
 
   if opt_level >= 1:

tests/runner.py

@@ -105,14 +105,20 @@ class RunnerCore(unittest.TestCase):
         shutil.copyfile(filename + '.o.js', filename + '.o.js.prepost.js')
         process(filename + '.o.js')
     else:
-      if post_build is not None:
-        os.environ['EMCC_JS_PROCESSOR'] = post_build
-      else:
-        try:
-          del os.environ['EMCC_JS_PROCESSOR']
-        except:
-          pass
-      Building.emcc(filename + '.o.ll', Settings.serialize() + self.emcc_args, filename + '.o.js')
+      transform_args = []
+      if post_build:
+        transform_filename = os.path.join(self.get_dir(), 'transform.py')
+        transform = open(transform_filename, 'w')
+        transform.write('''
+import sys
+''')
+        transform.write(post_build)
+        transform.write('''
+process(sys.argv[1])
+''')
+        transform.close()
+        transform_args = ['--js-transform', "python %s" % transform_filename]
+      Building.emcc(filename + '.o.ll', Settings.serialize() + self.emcc_args + transform_args, filename + '.o.js')
 
   # Build JavaScript code from source code
   def build(self, src, dirname, filename, output_processor=None, main_file=None, additional_files=[], libraries=[], includes=[], build_ll_hook=None, extra_emscripten_args=[], post_build=None):
@@ -5275,8 +5281,21 @@ Options that are modified or new in %s include:
           assert os.path.exists('combined.bc'), '\n'.join(output)
           self.assertContained('side got: hello from main, over', self.run_llvm_interpreter(['combined.bc']))
 
-      # TODO: Add an argument for EMCC_JS_PROCESSOR to make it simpler to use, other simplifications there (allow non-py, just run it if not .py)
-      #       Add in files test a clear example of using disablePermissions, and link to it from the wiki
+        # --js-transform <transform>
+        clear()
+        trans = os.path.join(self.get_dir(), 't.py')
+        trans_file = open(trans, 'w')
+        trans_file.write('''
+import sys
+f = open(sys.argv[1], 'w')
+f.write('transformed!')
+f.close()
+''')
+        trans_file.close()
+        output = Popen([compiler, path_from_root('tests', 'hello_world' + suffix), '--js-transform', 'python t.py'], stdout=PIPE, stderr=PIPE).communicate()
+        assert open('a.out.js').read() == 'transformed!', 'Transformed output must be as expected'
+
+      # TODO: Add in files test a clear example of using disablePermissions, and link to it from the wiki
       # TODO: test normal project linking, static and dynamic: get_library should not need to be told what to link!
       # TODO: deprecate llvm optimizations, dlmalloc, etc. in emscripten.py.