[PATCH 2/3] scripts/qapi: add QAPISchemaIfCond.rsgen()

[Paolo Bonzini <pbonzini@redhat.com>]

From: Marc-André Lureau <marcandre.lureau@redhat.com>

Generate Rust #[cfg(...)] guards from QAPI 'if' conditions.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Link: https://lore.kernel.org/r/20210907121943.3498701-15-marcandre.lureau@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 scripts/qapi/common.py | 16 ++++++++++++++++
 scripts/qapi/schema.py |  4 ++++
 2 files changed, 20 insertions(+)

diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py
index d7c8aa3365c..a8ea5792c11 100644
--- a/scripts/qapi/common.py
+++ b/scripts/qapi/common.py
@@ -199,6 +199,22 @@ def guardend(name: str) -> str:
                  name=c_fname(name).upper())
 
 
+def rsgen_ifcond(ifcond: Union[str, Dict[str, Any]]) -> str:
+
+    def cfg(ifcond: Union[str, Dict[str, Any]]):
+        if isinstance(ifcond, str):
+            return ifcond
+        if isinstance(ifcond, list):
+            return ', '.join([cfg(c) for c in ifcond])
+        oper, operands = next(iter(ifcond.items()))
+        operands = cfg(operands)
+        return f'{oper}({operands})'
+
+    if not ifcond:
+        return ''
+    return '#[cfg(%s)]' % cfg(ifcond)
+
+
 def gen_ifcond(ifcond: Optional[Union[str, Dict[str, Any]]],
                cond_fmt: str, not_fmt: str,
                all_operator: str, any_operator: str) -> str:
diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py
index cbe3b5aa91e..0fb151b5d89 100644
--- a/scripts/qapi/schema.py
+++ b/scripts/qapi/schema.py
@@ -39,6 +39,7 @@
     docgen_ifcond,
     gen_endif,
     gen_if,
+    rsgen_ifcond,
 )
 from .error import QAPIError, QAPISemError, QAPISourceError
 from .expr import check_exprs
@@ -65,6 +66,9 @@ def gen_endif(self) -> str:
     def docgen(self) -> str:
         return docgen_ifcond(self.ifcond)
 
+    def rsgen(self) -> str:
+        return rsgen_ifcond(self.ifcond)
+
     def is_present(self) -> bool:
         return bool(self.ifcond)
 
-- 
2.49.0