qapi: introduce QAPISchemaIfCond.cgen()

Instead of building prepocessor conditions from a list of string, use
the result generated from QAPISchemaIfCond.cgen() and hide the
implementation details.

Note: this patch introduces a minor regression, generating a redundant
pair of parenthesis. This is mostly fixed in a later patch in this
series ("qapi: replace if condition list with dict [..]")

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20210804083105.97531-5-marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Commit message tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>

6 files changed, 46 insertions, 34 deletions

diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py
index 6ad1eeb61d..ba9fe14e4b 100644
--- a/scripts/qapi/common.py
+++ b/scripts/qapi/common.py
@@ -12,7 +12,12 @@
 # See the COPYING file in the top-level directory.
 
 import re
-from typing import Match, Optional, Sequence
+from typing import (
+    List,
+    Match,
+    Optional,
+    Union,
+)
 
 
 #: Magic string that gets removed along with all space to its right.
@@ -194,22 +199,26 @@ def guardend(name: str) -> str:
                  name=c_fname(name).upper())
 
 
-def gen_if(ifcond: Sequence[str]) -> str:
-    ret = ''
-    for ifc in ifcond:
-        ret += mcgen('''
+def cgen_ifcond(ifcond: Union[str, List[str]]) -> str:
+    if not ifcond:
+        return ''
+    return '(' + ') && ('.join(ifcond) + ')'
+
+
+def gen_if(cond: str) -> str:
+    if not cond:
+        return ''
+    return mcgen('''
 #if %(cond)s
-''', cond=ifc)
-    return ret
+''', cond=cond)
 
 
-def gen_endif(ifcond: Sequence[str]) -> str:
-    ret = ''
-    for ifc in reversed(ifcond):
-        ret += mcgen('''
+def gen_endif(cond: str) -> str:
+    if not cond:
+        return ''
+    return mcgen('''
 #endif /* %(cond)s */
-''', cond=ifc)
-    return ret
+''', cond=cond)
 
 
 def must_match(pattern: str, string: str) -> Match[str]:
diff --git a/scripts/qapi/gen.py b/scripts/qapi/gen.py
index 1c5b190276..51a597a025 100644
--- a/scripts/qapi/gen.py
+++ b/scripts/qapi/gen.py
@@ -95,9 +95,9 @@ def _wrap_ifcond(ifcond: QAPISchemaIfCond, before: str, after: str) -> str:
     if added[0] == '\n':
         out += '\n'
         added = added[1:]
-    out += gen_if(ifcond.ifcond)
+    out += gen_if(ifcond.cgen())
     out += added
-    out += gen_endif(ifcond.ifcond)
+    out += gen_endif(ifcond.cgen())
     return out
 
 
diff --git a/scripts/qapi/introspect.py b/scripts/qapi/introspect.py
index e23725e2f9..bd4233ecee 100644
--- a/scripts/qapi/introspect.py
+++ b/scripts/qapi/introspect.py
@@ -124,10 +124,10 @@ def _tree_to_qlit(obj: JSONValue,
         if obj.comment:
             ret += indent(level) + f"/* {obj.comment} */\n"
         if obj.ifcond.is_present():
-            ret += gen_if(obj.ifcond.ifcond)
+            ret += gen_if(obj.ifcond.cgen())
         ret += _tree_to_qlit(obj.value, level)
         if obj.ifcond.is_present():
-            ret += '\n' + gen_endif(obj.ifcond.ifcond)
+            ret += '\n' + gen_endif(obj.ifcond.cgen())
         return ret
 
     ret = ''
diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py
index 86fcd6cbd5..4ea7e88846 100644
--- a/scripts/qapi/schema.py
+++ b/scripts/qapi/schema.py
@@ -19,7 +19,7 @@ import os
 import re
 from typing import Optional
 
-from .common import POINTER_SUFFIX, c_name
+from .common import POINTER_SUFFIX, c_name, cgen_ifcond
 from .error import QAPIError, QAPISemError, QAPISourceError
 from .expr import check_exprs
 from .parser import QAPISchemaParser
@@ -29,6 +29,9 @@ class QAPISchemaIfCond:
     def __init__(self, ifcond=None):
         self.ifcond = ifcond or []
 
+    def cgen(self):
+        return cgen_ifcond(self.ifcond)
+
     def is_present(self):
         return bool(self.ifcond)
 
diff --git a/scripts/qapi/types.py b/scripts/qapi/types.py
index 3673cf0f49..db9ff95bd1 100644
--- a/scripts/qapi/types.py
+++ b/scripts/qapi/types.py
@@ -51,13 +51,13 @@ const QEnumLookup %(c_name)s_lookup = {
 ''',
                 c_name=c_name(name))
     for memb in members:
-        ret += gen_if(memb.ifcond.ifcond)
+        ret += gen_if(memb.ifcond.cgen())
         index = c_enum_const(name, memb.name, prefix)
         ret += mcgen('''
         [%(index)s] = "%(name)s",
 ''',
                      index=index, name=memb.name)
-        ret += gen_endif(memb.ifcond.ifcond)
+        ret += gen_endif(memb.ifcond.cgen())
 
     ret += mcgen('''
     },
@@ -81,12 +81,12 @@ typedef enum %(c_name)s {
                 c_name=c_name(name))
 
     for memb in enum_members:
-        ret += gen_if(memb.ifcond.ifcond)
+        ret += gen_if(memb.ifcond.cgen())
         ret += mcgen('''
     %(c_enum)s,
 ''',
                      c_enum=c_enum_const(name, memb.name, prefix))
-        ret += gen_endif(memb.ifcond.ifcond)
+        ret += gen_endif(memb.ifcond.cgen())
 
     ret += mcgen('''
 } %(c_name)s;
@@ -126,7 +126,7 @@ struct %(c_name)s {
 def gen_struct_members(members: List[QAPISchemaObjectTypeMember]) -> str:
     ret = ''
     for memb in members:
-        ret += gen_if(memb.ifcond.ifcond)
+        ret += gen_if(memb.ifcond.cgen())
         if memb.optional:
             ret += mcgen('''
     bool has_%(c_name)s;
@@ -136,7 +136,7 @@ def gen_struct_members(members: List[QAPISchemaObjectTypeMember]) -> str:
     %(c_type)s %(c_name)s;
 ''',
                      c_type=memb.type.c_type(), c_name=c_name(memb.name))
-        ret += gen_endif(memb.ifcond.ifcond)
+        ret += gen_endif(memb.ifcond.cgen())
     return ret
 
 
@@ -159,7 +159,7 @@ def gen_object(name: str, ifcond: QAPISchemaIfCond,
     ret += mcgen('''
 
 ''')
-    ret += gen_if(ifcond.ifcond)
+    ret += gen_if(ifcond.cgen())
     ret += mcgen('''
 struct %(c_name)s {
 ''',
@@ -193,7 +193,7 @@ struct %(c_name)s {
     ret += mcgen('''
 };
 ''')
-    ret += gen_endif(ifcond.ifcond)
+    ret += gen_endif(ifcond.cgen())
 
     return ret
 
@@ -220,13 +220,13 @@ def gen_variants(variants: QAPISchemaVariants) -> str:
     for var in variants.variants:
         if var.type.name == 'q_empty':
             continue
-        ret += gen_if(var.ifcond.ifcond)
+        ret += gen_if(var.ifcond.cgen())
         ret += mcgen('''
         %(c_type)s %(c_name)s;
 ''',
                      c_type=var.type.c_unboxed_type(),
                      c_name=c_name(var.name))
-        ret += gen_endif(var.ifcond.ifcond)
+        ret += gen_endif(var.ifcond.cgen())
 
     ret += mcgen('''
     } u;
diff --git a/scripts/qapi/visit.py b/scripts/qapi/visit.py
index 67721b2470..56ea516399 100644
--- a/scripts/qapi/visit.py
+++ b/scripts/qapi/visit.py
@@ -79,7 +79,7 @@ bool visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp)
 
     for memb in members:
         deprecated = 'deprecated' in [f.name for f in memb.features]
-        ret += gen_if(memb.ifcond.ifcond)
+        ret += gen_if(memb.ifcond.cgen())
         if memb.optional:
             ret += mcgen('''
     if (visit_optional(v, "%(name)s", &obj->has_%(c_name)s)) {
@@ -112,7 +112,7 @@ bool visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp)
             ret += mcgen('''
     }
 ''')
-        ret += gen_endif(memb.ifcond.ifcond)
+        ret += gen_endif(memb.ifcond.cgen())
 
     if variants:
         tag_member = variants.tag_member
@@ -126,7 +126,7 @@ bool visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp)
         for var in variants.variants:
             case_str = c_enum_const(tag_member.type.name, var.name,
                                     tag_member.type.prefix)
-            ret += gen_if(var.ifcond.ifcond)
+            ret += gen_if(var.ifcond.cgen())
             if var.type.name == 'q_empty':
                 # valid variant and nothing to do
                 ret += mcgen('''
@@ -142,7 +142,7 @@ bool visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp)
                              case=case_str,
                              c_type=var.type.c_name(), c_name=c_name(var.name))
 
-            ret += gen_endif(var.ifcond.ifcond)
+            ret += gen_endif(var.ifcond.cgen())
         ret += mcgen('''
     default:
         abort();
@@ -228,7 +228,7 @@ bool visit_type_%(c_name)s(Visitor *v, const char *name,
                 c_name=c_name(name))
 
     for var in variants.variants:
-        ret += gen_if(var.ifcond.ifcond)
+        ret += gen_if(var.ifcond.cgen())
         ret += mcgen('''
     case %(case)s:
 ''',
@@ -254,7 +254,7 @@ bool visit_type_%(c_name)s(Visitor *v, const char *name,
         ret += mcgen('''
         break;
 ''')
-        ret += gen_endif(var.ifcond.ifcond)
+        ret += gen_endif(var.ifcond.cgen())
 
     ret += mcgen('''
     case QTYPE_NONE: