qapi: Proper intermediate representation for modules

Modules are represented only by their names so far.  Introduce class
QAPISchemaModule.  So far, it merely wraps the name.  The next patch
will put it to more interesting use.

Once again, arrays spice up the patch a bit.  For any other type,
@info points to the definition, which lets us map from @info to
module.  For arrays, there is no definition, and @info points to the
first use instead.  We have to use the element type's module instead,
which is only available after .check().

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20191120182551.23795-5-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

scripts/qapi/schema.py

@@ -50,9 +50,6 @@ class QAPISchemaEntity(object):
 
     def check(self, schema):
         assert not self._checked
-        if self.info:
-            self._module = os.path.relpath(self.info.fname,
-                                           os.path.dirname(schema.fname))
         seen = {}
         for f in self.features:
             f.check_clash(self.info, seen)
@@ -68,6 +65,13 @@ class QAPISchemaEntity(object):
         if self.doc:
             self.doc.check()
 
+    def _set_module(self, schema, info):
+        assert self._checked
+        self._module = schema.module_by_fname(info and info.fname)
+
+    def set_module(self, schema):
+        self._set_module(schema, self.info)
+
     @property
     def ifcond(self):
         assert self._checked
@@ -75,7 +79,7 @@ class QAPISchemaEntity(object):
 
     @property
     def module(self):
-        assert self._checked
+        assert self._module or not self.info
         return self._module
 
     def is_implicit(self):
@@ -135,15 +139,19 @@ class QAPISchemaVisitor(object):
         pass
 
 
-class QAPISchemaInclude(QAPISchemaEntity):
+class QAPISchemaModule(object):
+    def __init__(self, name):
+        self.name = name
 
-    def __init__(self, fname, info):
+
+class QAPISchemaInclude(QAPISchemaEntity):
+    def __init__(self, sub_module, info):
         QAPISchemaEntity.__init__(self, None, info, None)
-        self.fname = fname
+        self._sub_module = sub_module
 
     def visit(self, visitor):
         QAPISchemaEntity.visit(self, visitor)
-        visitor.visit_include(self.fname, self.info)
+        visitor.visit_include(self._sub_module.name, self.info)
 
 
 class QAPISchemaType(QAPISchemaEntity):
@@ -276,16 +284,14 @@ class QAPISchemaArrayType(QAPISchemaType):
             self.info and self.info.defn_meta)
         assert not isinstance(self.element_type, QAPISchemaArrayType)
 
+    def set_module(self, schema):
+        self._set_module(schema, self.element_type.info)
+
     @property
     def ifcond(self):
         assert self._checked
         return self.element_type.ifcond
 
-    @property
-    def module(self):
-        assert self._checked
-        return self.element_type.module
-
     def is_implicit(self):
         return True
 
@@ -783,6 +789,10 @@ class QAPISchema(object):
         self.docs = parser.docs
         self._entity_list = []
         self._entity_dict = {}
+        self._module_dict = {}
+        self._schema_dir = os.path.dirname(fname)
+        self._make_module(None) # built-ins
+        self._make_module(fname)
         self._predefining = True
         self._def_predefineds()
         self._predefining = False
@@ -826,14 +836,26 @@ class QAPISchema(object):
                 info, "%s uses unknown type '%s'" % (what, name))
         return typ
 
+    def _module_name(self, fname):
+        if fname is None:
+            return None
+        return os.path.relpath(fname, self._schema_dir)
+
+    def _make_module(self, fname):
+        name = self._module_name(fname)
+        if not name in self._module_dict:
+            self._module_dict[name] = QAPISchemaModule(name)
+        return self._module_dict[name]
+
+    def module_by_fname(self, fname):
+        name = self._module_name(fname)
+        assert name in self._module_dict
+        return self._module_dict[name]
+
     def _def_include(self, expr, info, doc):
         include = expr['include']
         assert doc is None
-        main_info = info
-        while main_info.parent:
-            main_info = main_info.parent
-        fname = os.path.relpath(include, os.path.dirname(main_info.fname))
-        self._def_entity(QAPISchemaInclude(fname, info))
+        self._def_entity(QAPISchemaInclude(self._make_module(include), info))
 
     def _def_builtin_type(self, name, json_type, c_type):
         self._def_entity(QAPISchemaBuiltinType(name, json_type, c_type))
@@ -1065,15 +1087,16 @@ class QAPISchema(object):
             ent.check(self)
             ent.connect_doc()
             ent.check_doc()
+        for ent in self._entity_list:
+            ent.set_module(self)
 
     def visit(self, visitor):
         visitor.visit_begin(self)
         module = None
-        visitor.visit_module(module)
         for entity in self._entity_list:
             if visitor.visit_needed(entity):
                 if entity.module != module:
                     module = entity.module
-                    visitor.visit_module(module)
+                    visitor.visit_module(module.name)
                 entity.visit(visitor)
         visitor.visit_end()