qapi: add 'if' to top-level expressions

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.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20180703155648.11933-2-marcandre.lureau@redhat.com>
[Commit message and Documentation improved]
Signed-off-by: Markus Armbruster <armbru@redhat.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/tests/qapi-schema/qapi-schema-test.json b/tests/qapi-schema/qapi-schema-test.json
index 7b59817f04..16209b57b3 100644
--- a/tests/qapi-schema/qapi-schema-test.json
+++ b/tests/qapi-schema/qapi-schema-test.json
@@ -56,6 +56,9 @@
   'data': { 'string0': 'str',
             'dict1': 'UserDefTwoDict' } }
 
+{ 'struct': 'UserDefThree',
+  'data': { 'string0': 'str' } }
+
 # dummy struct to force generation of array types not otherwise mentioned
 { 'struct': 'ForceArrays',
   'data': { 'unused1':['UserDefOne'], 'unused2':['UserDefTwo'],
@@ -193,3 +196,26 @@
   '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' },
+  'returns': 'UserDefThree',
+  'if': ['defined(TEST_IF_CMD)', 'defined(TEST_IF_STRUCT)'] }
+
+{ 'command': 'TestCmdReturnDefThree', 'returns': 'UserDefThree' }
+
+{ 'event': 'TestIfEvent', 'data': { 'foo': 'TestIfStruct' },
+  'if': 'defined(TEST_IF_EVT) && defined(TEST_IF_STRUCT)' }