Add js_interface_generator for generating extensions interfaces

tools/json_schema_compiler/compiler.py

Index: tools/json_schema_compiler/compiler.py
diff --git a/tools/json_schema_compiler/compiler.py b/tools/json_schema_compiler/compiler.py
index 1ed407bef6f9bf6ac77db9117bf60838a499b5cd..01bdc09240202ba30f92fff3c8af961e4460889c 100755
--- a/tools/json_schema_compiler/compiler.py
+++ b/tools/json_schema_compiler/compiler.py
@@ -25,6 +25,7 @@ from cpp_bundle_generator import CppBundleGenerator
 from cpp_generator import CppGenerator
 from cpp_type_generator import CppTypeGenerator
 from js_externs_generator import JsExternsGenerator
+from js_interface_generator import JsInterfaceGenerator
 import json_schema
 from cpp_namespace_environment import CppNamespaceEnvironment
 from model import Model
@@ -32,7 +33,9 @@ from schema_loader import SchemaLoader
 
 # Names of supported code generators, as specified on the command-line.
 # First is default.
-GENERATORS = ['cpp', 'cpp-bundle-registration', 'cpp-bundle-schema', 'externs']
+GENERATORS = [
+  'cpp', 'cpp-bundle-registration', 'cpp-bundle-schema', 'externs', 'interface'
+]
 
 def GenerateSchema(generator_name,
                    file_paths,
@@ -122,6 +125,10 @@ def GenerateSchema(generator_name,
     generators = [
       ('%s_externs.js' % namespace.unix_name, JsExternsGenerator())
     ]
+  elif generator_name == 'interface':
+    generators = [
+      ('%s_interface.js' % namespace.unix_name, JsInterfaceGenerator())
+    ]
   else:
     raise Exception('Unrecognised generator %s' % generator_name)
 
@@ -139,7 +146,10 @@ def GenerateSchema(generator_name,
         os.makedirs(output_dir)
       with open(os.path.join(output_dir, filename), 'w') as f:
         f.write(code)
-    output_code += [filename, '', code, '']
+    if len(generators) > 1:
+      output_code += [filename, '', code, '']

[michaelpg, 2015/12/04 21:02:19]

is this where the silly filename at the beginning of extern output comes from?
can we just... not?

[stevenjb, 2015/12/07 18:31:24]

It is. And this is correct: If we are writing a single file to std:out, we want
to skip the "sill" filename at the beginning. However if we generate, e.g., a
.cc and a .h to stdout then the filename separators are helpful.
Added a comment.

[michaelpg, 2015/12/07 18:46:53]

ah, I didn't realize that's what |generators| represented. Yay, thanks!
Does any *nix utility do this? it's wildly unexpected behavior and goes against
the "philosophy" of text-transforming tools IMO. Not a reason to change it now,
though.

[stevenjb, 2015/12/07 19:49:32]

So, I *think* that the intention is to specify an output directory and the
.cc/.h files will be placed there (see if destdir: above). I seem to recall
problems with specifying an output directory for the JS externs (or maybe
decided it was too much hassle?). Either way, this is at least an improvement to
the way we've been generating externs (and now interfaces) without affecting
existing behavior for other generators.

+    else:
+      output_code += [code]
 
   return '\n'.join(output_code)