Fix "implements in RHS file"

Recent CL broke run-bindings-tests on my machine:
Move modules-dependent IDL statements out of core by supporting 'implements' in RHS interface
https://codereview.chromium.org/270573005/

This is due to depending on order of files;
this is fixed by doing the moving/merging in a separate, global phase
(which we're already doing).

Also:
* Adds a test case.
* Fixes unaddressed nits.

R=haraken
BUG=358074

Review URL: https://codereview.chromium.org/270823002

git-svn-id: svn://svn.chromium.org/blink/trunk@173613 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/bindings/scripts/compute_interfaces_info.py

@@ -173,11 +173,16 @@ def compute_individual_info(idl_filename):
     # If not a partial interface, the basename is the interface name
     interface_name, _ = os.path.splitext(os.path.basename(idl_filename))
 
+    # 'implements' statements can be included in either the file for the
+    # implement*ing* interface (lhs of 'implements') or implement*ed* interface
+    # (rhs of 'implements'). Store both for now, then merge to implement*ing*
+    # interface later.
     left_interfaces, right_interfaces = get_implements_from_idl(idl_file_contents, interface_name)
 
     interfaces_info[interface_name] = {
         'full_path': full_path,
         'implemented_as': implemented_as,
+        'implemented_by_interfaces': left_interfaces,  # private, merged to next
         'implements_interfaces': right_interfaces,
         'include_path': this_include_path,
         # FIXME: temporary private field, while removing old treatement of
@@ -193,10 +198,6 @@ def compute_individual_info(idl_filename):
         'referenced_interfaces': get_put_forward_interfaces_from_idl(idl_file_contents),
     }
 
-    for left_interface_name in left_interfaces:
-        interface_info = interfaces_info[left_interface_name]
-        interface_info['implements_interfaces'].append(interface_name)
-
     # Record inheritance information
     inherited_extended_attributes_by_interface[interface_name] = dict(
             (key, value)
@@ -246,6 +247,15 @@ def compute_interfaces_info(idl_files):
         compute_inheritance_info(interface_name)
 
     # Compute dependencies
+    # Move implements info from implement*ed* interface (rhs of 'implements')
+    # to implement*ing* interface (lhs of 'implements').
+    # Note that moving an 'implements' statement between implementing and
+    # implemented files does not change the info (or hence cause a rebuild)!
+    for right_interface_name, interface_info in interfaces_info.iteritems():
+        for left_interface_name in interface_info['implemented_by_interfaces']:
+            interfaces_info[left_interface_name]['implements_interfaces'].append(right_interface_name)
+        del interface_info['implemented_by_interfaces']
+
     # An IDL file's dependencies are partial interface files that extend it,
     # and files for other interfaces that this interfaces implements.
     for interface_name, interface_info in interfaces_info.iteritems():

third_party/WebKit/Source/bindings/scripts/utilities.py

@@ -59,27 +59,38 @@ def get_partial_interface_name_from_idl(file_contents):
 
 
 def get_implements_from_idl(file_contents, interface_name):
-    # Rule is: identifier-A implements identifier-B;
-    # http://www.w3.org/TR/WebIDL/#idl-implements-statements
-    # Returns two lists of interfaces that contain identifier-As and identifier-Bs.
-    # The 'implements' statements are supported in both identifier-A IDL and identifier-B IDL
-    # to avoid potential layering violation.
+    """Returns lists of implementing and implemented interfaces.
+
+    Rule is: identifier-A implements identifier-B;
+    i.e., implement*ing* implements implement*ed*;
+    http://www.w3.org/TR/WebIDL/#idl-implements-statements
+
+    Returns two lists of interfaces: identifier-As and identifier-Bs.
+    An 'implements' statements can be present in the IDL file for either the
+    implementing or the implemented interface, but not other files.
+    """
     implements_re = (r'^\s*'
                      r'(\w+)\s+'
                      r'implements\s+'
                      r'(\w+)\s*'
                      r';')
     implements_matches = re.finditer(implements_re, file_contents, re.MULTILINE)
-    implements_pairs = [(match.group(1), match.group(2))
-                        for match in implements_matches]
-    A_interfaces = []
-    B_interfaces = []
-    for left, right in implements_pairs:
-        if left == interface_name:
-            B_interfaces.append(right)
-        elif right == interface_name:
-            A_interfaces.append(left)
-    return (A_interfaces, B_interfaces)
+    implements_pairs = [match.groups() for match in implements_matches]
+
+    foreign_implements = [pair for pair in implements_pairs
+                          if interface_name not in pair]
+    if foreign_implements:
+        left, right = foreign_implements.pop()
+        raise IdlBadFilenameError(
+                'implements statement found in unrelated IDL file.\n'
+                'Statement is:\n'
+                '    %s implements %s;\n'
+                'but filename is unrelated "%s.idl"' %
+                (left, right, interface_name))
+
+    return (
+        [left for left, right in implements_pairs if right == interface_name],
+        [right for left, right in implements_pairs if left == interface_name])
 
 
 def is_callback_interface_from_idl(file_contents):

third_party/WebKit/Source/bindings/tests/idls/TestImplements2.idl

@@ -37,3 +37,5 @@
     attribute DOMString implements2StringAttribute;
     void implements2VoidMethod();
 };
+
+TestInterface implements TestImplements2;

third_party/WebKit/Source/bindings/tests/idls/TestInterface.idl

@@ -72,5 +72,5 @@
 };
 
 TestInterface implements TestImplements;
-TestInterface implements TestImplements2;
+// TestInterface implements TestImplements2; // at implement*ed* interface
 TestInterface implements TestImplements3;