Make SchemaLoader independent of current working directory.

tools/json_schema_compiler/schema_loader.py

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import os
 import sys
 
 import idl_schema
 import json_schema
 from model import Model
 
 class SchemaLoader(object):
   '''Resolves a type name into the namespace the type belongs to.
   '''
-  def __init__(self, api_path):
+  def __init__(self, root, api_path):
+    self._root = root
     self._api_path = api_path
 
   def ResolveType(self, full_name, default_namespace):
     name_parts = full_name.rsplit('.', 1)
     if len(name_parts) == 1:
       if full_name not in default_namespace.types:
         return None
       return default_namespace
     namespace_name, type_name = name_parts
     real_name = None
     for ext in ['json', 'idl']:
       filename = '%s.%s' % (namespace_name, ext)
-      if os.path.exists(filename):
+      filepath = os.path.join(self._root, self._api_path, filename);
+      if os.path.exists(filepath):
         real_name = filename
         break
     if real_name is None:
       return None
     namespace = Model().AddNamespace(self.LoadSchema(real_name)[0],
                                      os.path.join(self._api_path, real_name))
     if type_name not in namespace.types:
       return None
     return namespace
 
   def LoadSchema(self, schema):
+    '''Load a schema definition. The schema parameter must be a file name
+       without any path component - the file is loaded from the path defined by
+       the root and api_path arguments passed to the constructor.'''
     schema_filename, schema_extension = os.path.splitext(schema)
 
+    schema_path = os.path.join(self._root, self._api_path, schema);

[not at google - send to devlin, 2013/09/19 15:43:34]

can the caller just make sure that the root is properly prepended to api_path?

[msimonides, 2013/09/20 11:32:01]

This would be a problem with line 35-36: Model().AddNamespace(). If I modify the
_api_path as you suggest, the generated header files will have incorrect
#include paths.

[not at google - send to devlin, 2013/09/20 20:37:57]

Ah. So there's a long-standing cleanup where we don't actually need the api path
to be passed into those Namespaces, they should be passed into the code
generators.

But unless you're keen to fix that now (which would be great, but I would
understand if not), I'd still rather pass in 2 separate paths rather than 1 path
and a root.

     if schema_extension == '.json':
-      api_defs = json_schema.Load(schema)
+      api_defs = json_schema.Load(schema_path)
     elif schema_extension == '.idl':
-      api_defs = idl_schema.Load(schema)
+      api_defs = idl_schema.Load(schema_path)
     else:
       sys.exit('Did not recognize file extension %s for schema %s' %
                (schema_extension, schema))
     if len(api_defs) != 1:
       sys.exit('File %s has multiple schemas. Files are only allowed to contain'
                'a single schema.' % schema)
 
     return api_defs