[Qemu-devel] [PATCH v6 01/12] qapi: Use predicate callback to determine visit filtering

[Eric Blake <eblake@redhat.com>]

Previously, qapi-types and qapi-visit filtered out implicit
objects during visit_object_type() by using 'info' (works since
implicit objects do not [yet] have associated info); meanwhile
qapi-introspect filtered out all schema types on the first pass
by returning a python type from visit_begin(), which was then
used in QAPISchema.visit().  Rather than keeping these ad hoc
approaches, add a new visitor callback visit_predicate() which
returns False to skip a given entity, and which defaults to
True unless overridden.  Use the new mechanism to simplify all
three visitors that need filtering.  No change to the generated
code.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>

---
v6: new patch
---
 scripts/qapi-introspect.py |  5 ++++-
 scripts/qapi-types.py      | 18 ++++++++++--------
 scripts/qapi-visit.py      | 16 +++++++++-------
 scripts/qapi.py            | 11 +++++++----
 4 files changed, 30 insertions(+), 20 deletions(-)

diff --git a/scripts/qapi-introspect.py b/scripts/qapi-introspect.py
index 7d39320..f30fac3 100644
--- a/scripts/qapi-introspect.py
+++ b/scripts/qapi-introspect.py
@@ -54,7 +54,6 @@ class QAPISchemaGenIntrospectVisitor(QAPISchemaVisitor):
         self._jsons = []
         self._used_types = []
         self._name_map = {}
-        return QAPISchemaType   # don't visit types for now

     def visit_end(self):
         # visit the types that are actually used
@@ -82,6 +81,10 @@ const char %(c_name)s[] = %(c_string)s;
         self._used_types = None
         self._name_map = None

+    def visit_predicate(self, entity):
+        # Ignore types on first pass; visit_end() will pick up used types
+        return not isinstance(entity, QAPISchemaType)
+
     def _name(self, name):
         if self._unmask:
             return name
diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py
index d405f8d..c5b71b0 100644
--- a/scripts/qapi-types.py
+++ b/scripts/qapi-types.py
@@ -233,6 +233,9 @@ class QAPISchemaGenTypeVisitor(QAPISchemaVisitor):
         self.decl = self._btin + self.decl
         self._btin = None

+    def visit_predicate(self, entity):
+        return not isinstance(entity, QAPISchemaObjectType) or entity.info
+
     def _gen_type_cleanup(self, name):
         self.decl += gen_type_cleanup_decl(name)
         self.defn += gen_type_cleanup(name)
@@ -254,14 +257,13 @@ class QAPISchemaGenTypeVisitor(QAPISchemaVisitor):
             self._gen_type_cleanup(name)

     def visit_object_type(self, name, info, base, members, variants):
-        if info:
-            self._fwdecl += gen_fwd_object_or_array(name)
-            if variants:
-                assert not members      # not implemented
-                self.decl += gen_union(name, base, variants)
-            else:
-                self.decl += gen_struct(name, base, members)
-            self._gen_type_cleanup(name)
+        self._fwdecl += gen_fwd_object_or_array(name)
+        if variants:
+            assert not members      # not implemented
+            self.decl += gen_union(name, base, variants)
+        else:
+            self.decl += gen_struct(name, base, members)
+        self._gen_type_cleanup(name)

     def visit_alternate_type(self, name, info, variants):
         self._fwdecl += gen_fwd_object_or_array(name)
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 4f97781..0f47614 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -333,6 +333,9 @@ class QAPISchemaGenVisitVisitor(QAPISchemaVisitor):
         self.decl = self._btin + self.decl
         self._btin = None

+    def visit_predicate(self, entity):
+        return not isinstance(entity, QAPISchemaObjectType) or entity.info
+
     def visit_enum_type(self, name, info, values, prefix):
         self.decl += gen_visit_decl(name, scalar=True)
         self.defn += gen_visit_enum(name)
@@ -349,13 +352,12 @@ class QAPISchemaGenVisitVisitor(QAPISchemaVisitor):
             self.defn += defn

     def visit_object_type(self, name, info, base, members, variants):
-        if info:
-            self.decl += gen_visit_decl(name)
-            if variants:
-                assert not members      # not implemented
-                self.defn += gen_visit_union(name, base, variants)
-            else:
-                self.defn += gen_visit_struct(name, base, members)
+        self.decl += gen_visit_decl(name)
+        if variants:
+            assert not members      # not implemented
+            self.defn += gen_visit_union(name, base, variants)
+        else:
+            self.defn += gen_visit_struct(name, base, members)

     def visit_alternate_type(self, name, info, variants):
         self.decl += gen_visit_decl(name)
diff --git a/scripts/qapi.py b/scripts/qapi.py
index 26cff3f..7d359c8 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -811,6 +811,9 @@ class QAPISchemaVisitor(object):
     def visit_end(self):
         pass

+    def visit_predicate(self, entity):
+        return True
+
     def visit_builtin_type(self, name, info, json_type):
         pass

@@ -1304,10 +1307,10 @@ class QAPISchema(object):
             ent.check(self)

     def visit(self, visitor):
-        ignore = visitor.visit_begin(self)
-        for name in sorted(self._entity_dict.keys()):
-            if not ignore or not isinstance(self._entity_dict[name], ignore):
-                self._entity_dict[name].visit(visitor)
+        visitor.visit_begin(self)
+        for (name, entity) in sorted(self._entity_dict.items()):
+            if visitor.visit_predicate(entity):
+                entity.visit(visitor)
         visitor.visit_end()


-- 
2.4.3