nanopb: update generator to emit optional enum->string mapping function

Google-Bug-Id: 28000875
Signed-off-by: William A. Kennington III <wak@google.com>
Change-Id: I1bffd39168abe04593588291b0ebbe5199a00138

2 files changed, 27 insertions, 0 deletions

diff --git a/generator/nanopb_generator.py b/generator/nanopb_generator.py
index 9ccb9b93..36cbbdfa 100755
--- a/generator/nanopb_generator.py
+++ b/generator/nanopb_generator.py
@@ -207,6 +207,27 @@ class Enum:
             for i, x in enumerate(self.values):
                 result += '\n#define %s %s' % (self.value_longnames[i], x[0])
 
+        if self.options.enum_to_string:
+            result += '\nconst char *%s_Name(%s v);\n' % (self.names, self.names)
+
+        return result
+
+    def enum_definition(self):
+        if not self.options.enum_to_string:
+            return ""
+
+        result = 'const char *%s_Name(%s v) {\n' % (self.names, self.names)
+        result += '    switch (v) {\n'
+
+        for ((enumname, _), strname) in zip(self.values, self.value_longnames):
+            # Strip off the leading type name from the string value.
+            strval = str(strname)[len(str(self.names)) + 1:]
+            result += '    case %s: return "%s";\n' % (enumname, strval)
+
+        result += '    }\n'
+        result += '    return "unknown";\n'
+        result += '}\n'
+
         return result
 
 class FieldMaxSize:
@@ -1220,6 +1241,9 @@ class ProtoFile:
         for ext in self.extensions:
             yield ext.extension_def() + '\n'
 
+        for enum in self.enums:
+            yield enum.enum_definition() + '\n'
+
         # Add checks for numeric limits
         if self.messages:
             largest_msg = max(self.messages, key = lambda m: m.count_required_fields())
diff --git a/generator/proto/nanopb.proto b/generator/proto/nanopb.proto
index b9961c88..f6fe4a20 100644
--- a/generator/proto/nanopb.proto
+++ b/generator/proto/nanopb.proto
@@ -69,6 +69,9 @@ message NanoPBOptions {
 
   // Proto3 singular field does not generate a "has_" flag
   optional bool proto3 = 12 [default = false];
+
+  // Generate an enum->string mapping function (can take up lots of space).
+  optional bool enum_to_string = 13 [default = false];
 }
 
 // Extensions to protoc 'Descriptor' type in order to define options