[Qemu-devel] [PATCH v3 04/50] qapi: add 'if' to top-level expressions

[Marc-André Lureau]

Accept 'if' key in top-level elements, accepted as string or list of
string type. The following patches will modify the test visitor to
check the value is correctly saved, and generate #if/#endif code (as a
single #if/endif line or a series for a list).

Example of 'if' key:
{ 'struct': 'TestIfStruct', 'data': { 'foo': 'int' },
  'if': 'defined(TEST_IF_STRUCT)' }

The generated code is for now *unconditional*. Later patches generate
the conditionals.

A following patch for qapi-code-gen.txt will provide more complete
documentation for 'if' usage.

Signed-off-by: Marc-André Lureau <address@hidden>
---
 scripts/qapi.py                         | 35 +++++++++++++++++++++++++++------
 tests/test-qmp-commands.c               |  6 ++++++
 tests/qapi-schema/qapi-schema-test.json | 20 +++++++++++++++++++
 tests/qapi-schema/qapi-schema-test.out  | 22 +++++++++++++++++++++
 4 files changed, 77 insertions(+), 6 deletions(-)

diff --git a/scripts/qapi.py b/scripts/qapi.py
index 62dc52ed6e..20c1abf915 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -639,6 +639,26 @@ def add_name(name, info, meta, implicit=False):
     all_names[name] = meta
 
 
+def check_if(expr, info):
+
+    def check_if_str(ifcond, info):
+        if ifcond == '':
+            raise QAPISemError(info, "'if' condition '' makes no sense")
+
+    ifcond = expr['if']
+    if isinstance(ifcond, str):
+        check_if_str(ifcond, info)
+    elif (isinstance(ifcond, list)
+          and all(isinstance(elt, str) for elt in ifcond)):
+        if ifcond == []:
+            raise QAPISemError(info, "'if' condition [] is useless")
+        for elt in ifcond:
+            check_if_str(elt, info)
+    else:
+        raise QAPISemError(
+            info, "'if' condition must be a string or a list of strings")
+
+
 def check_type(info, source, value, allow_array=False,
                allow_dict=False, allow_optional=False,
                allow_metas=[]):
@@ -878,6 +898,8 @@ def check_keys(expr_elem, meta, required, optional=[]):
             raise QAPISemError(info,
                                "'%s' of %s '%s' should only use true value"
                                % (key, meta, name))
+        if key == 'if':
+            check_if(expr, info)
     for key in required:
         if key not in expr:
             raise QAPISemError(info, "Key '%s' is missing from %s '%s'"
@@ -903,27 +925,28 @@ def check_exprs(exprs):
 
         if 'enum' in expr:
             meta = 'enum'
-            check_keys(expr_elem, 'enum', ['data'], ['prefix'])
+            check_keys(expr_elem, 'enum', ['data'], ['if', 'prefix'])
             enum_types[expr[meta]] = expr
         elif 'union' in expr:
             meta = 'union'
             check_keys(expr_elem, 'union', ['data'],
-                       ['base', 'discriminator'])
+                       ['base', 'discriminator', 'if'])
             union_types[expr[meta]] = expr
         elif 'alternate' in expr:
             meta = 'alternate'
-            check_keys(expr_elem, 'alternate', ['data'])
+            check_keys(expr_elem, 'alternate', ['data'], ['if'])
         elif 'struct' in expr:
             meta = 'struct'
-            check_keys(expr_elem, 'struct', ['data'], ['base'])
+            check_keys(expr_elem, 'struct', ['data'], ['base', 'if'])
             struct_types[expr[meta]] = expr
         elif 'command' in expr:
             meta = 'command'
             check_keys(expr_elem, 'command', [],
-                       ['data', 'returns', 'gen', 'success-response', 'boxed'])
+                       ['data', 'returns', 'gen', 'success-response', 'boxed',
+                        'if'])
         elif 'event' in expr:
             meta = 'event'
-            check_keys(expr_elem, 'event', [], ['data', 'boxed'])
+            check_keys(expr_elem, 'event', [], ['data', 'boxed', 'if'])
         else:
             raise QAPISemError(expr_elem['info'],
                                "Expression is missing metatype")
diff --git a/tests/test-qmp-commands.c b/tests/test-qmp-commands.c
index 904c89d4d4..9b9a7ffee7 100644
--- a/tests/test-qmp-commands.c
+++ b/tests/test-qmp-commands.c
@@ -10,6 +10,12 @@
 
 static QmpCommandList qmp_commands;
 
+/* #if defined(TEST_IF_CMD) */
+void qmp_TestIfCmd(TestIfStruct *foo, Error **errp)
+{
+}
+/* #endif */
+
 void qmp_user_def_cmd(Error **errp)
 {
 }
diff --git a/tests/qapi-schema/qapi-schema-test.json 
b/tests/qapi-schema/qapi-schema-test.json
index c72dbd8050..dc2c444fc1 100644
--- a/tests/qapi-schema/qapi-schema-test.json
+++ b/tests/qapi-schema/qapi-schema-test.json
@@ -188,3 +188,23 @@
   'data': { 'a': ['__org.qemu_x-Enum'], 'b': ['__org.qemu_x-Struct'],
             'c': '__org.qemu_x-Union2', 'd': '__org.qemu_x-Alt' },
   'returns': '__org.qemu_x-Union1' }
+
+# test 'if' condition handling
+
+{ 'struct': 'TestIfStruct', 'data': { 'foo': 'int' },
+  'if': 'defined(TEST_IF_STRUCT)' }
+
+{ 'enum': 'TestIfEnum', 'data': [ 'foo', 'bar' ],
+  'if': 'defined(TEST_IF_ENUM)' }
+
+{ 'union': 'TestIfUnion', 'data': { 'foo': 'TestStruct' },
+  'if': 'defined(TEST_IF_UNION) && defined(TEST_IF_STRUCT)' }
+
+{ 'alternate': 'TestIfAlternate', 'data': { 'foo': 'int', 'bar': 'TestStruct' 
},
+  'if': 'defined(TEST_IF_ALT) && defined(TEST_IF_STRUCT)' }
+
+{ 'command': 'TestIfCmd', 'data': { 'foo': 'TestIfStruct' },
+  'if': 'defined(TEST_IF_CMD) && defined(TEST_IF_STRUCT)' }
+
+{ 'event': 'TestIfEvent', 'data': { 'foo': 'TestIfStruct' },
+  'if': 'defined(TEST_IF_EVT) && defined(TEST_IF_STRUCT)' }
diff --git a/tests/qapi-schema/qapi-schema-test.out 
b/tests/qapi-schema/qapi-schema-test.out
index 3b1e9082d3..7fbaea19bc 100644
--- a/tests/qapi-schema/qapi-schema-test.out
+++ b/tests/qapi-schema/qapi-schema-test.out
@@ -52,6 +52,22 @@ enum QEnumTwo ['value1', 'value2']
     prefix QENUM_TWO
 enum QType ['none', 'qnull', 'qnum', 'qstring', 'qdict', 'qlist', 'qbool']
     prefix QTYPE
+alternate TestIfAlternate
+    tag type
+    case foo: int
+    case bar: TestStruct
+command TestIfCmd q_obj_TestIfCmd-arg -> None
+   gen=True success_response=True boxed=False
+enum TestIfEnum ['foo', 'bar']
+event TestIfEvent q_obj_TestIfEvent-arg
+   boxed=False
+object TestIfStruct
+    member foo: int optional=False
+object TestIfUnion
+    member type: TestIfUnionKind optional=False
+    tag type
+    case foo: q_obj_TestStruct-wrapper
+enum TestIfUnionKind ['foo']
 object TestStruct
     member integer: int optional=False
     member boolean: bool optional=False
@@ -172,6 +188,12 @@ object q_obj_EVENT_D-arg
     member b: str optional=False
     member c: str optional=True
     member enum3: EnumOne optional=True
+object q_obj_TestIfCmd-arg
+    member foo: TestIfStruct optional=False
+object q_obj_TestIfEvent-arg
+    member foo: TestIfStruct optional=False
+object q_obj_TestStruct-wrapper
+    member data: TestStruct optional=False
 object q_obj_UserDefFlatUnion2-base
     member integer: int optional=True
     member string: str optional=False
-- 
2.14.1.146.gd35faa819