Tracing V2: Field number constants for protobuf plugin.

components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "proto_zero_generator.h"
 
 #include <map>
 #include <memory>
 #include <set>
 #include <string>
@@ skipping 75 matching lines @@
   // prohibited but not recommended in order to avoid name collisions.
   template <class T>
   inline std::string GetCppClassName(const T* descriptor, bool full = false) {
     std::string name = GetDescriptorName(descriptor);
     StripString(&name, ".", '_');
     if (full)
       name = full_namespace_prefix_ + name;
     return name;
   }
 
+  template <class T>
+  inline std::string GetCamelCaseName(const T* descriptor, bool capitalize) {

[Primiano Tucci (use gerrit), 2016/08/05 11:34:18]

looks like capitalize is always = true.
Unless you plan to use this argument in next CLs please drop it.

+    std::string camel_name = descriptor->camelcase_name();
+    if (capitalize && !camel_name.empty())
+      camel_name.at(0) = toupper(camel_name.at(0));
+    return camel_name;
+  }
+
   // Small enums can be written faster without involving VarInt encoder.
   inline bool IsTinyEnumField(const FieldDescriptor* field) {
     if (field->type() != FieldDescriptor::TYPE_ENUM)
       return false;
     const EnumDescriptor* enumeration = field->enum_type();
 
     for (int i = 0; i < enumeration->value_count(); ++i) {
       int32_t value = enumeration->value(i)->number();
       if (value < 0 || value > 0x7F)
         return false;
@@ skipping 350 matching lines @@
       for (int j = 0; j < nested_enum->value_count(); ++j) {
         const EnumValueDescriptor* value = nested_enum->value(j);
         stub_h_->Print(
             "static const $class$ $name$ = $full_name$;\n",
             "class", nested_enum->name(),
             "name", value->name(),
             "full_name", value_name_prefix + value->name());
       }
     }
 
-    // Fields descriptors.
+    // Field numbers.
+    if (message->field_count() > 0) {
+      stub_h_->Print("enum : int32_t {\n");
+      stub_h_->Indent();
+
+      for (int i = 0; i < message->field_count(); ++i) {
+        const FieldDescriptor* field = message->field(i);
+        std::string name = GetCamelCaseName(field, true);
+        if (name.empty()) {
+          // Protoc allows fields like: 'bool _ = 1'.
+          Abort("Empty field name in camel case notation.");

[Primiano Tucci (use gerrit), 2016/08/05 11:34:18]

lol, TIL

+        }
+
+        stub_h_->Print(
+            "k$name$FieldNumber = $id$,\n",
+            "name", name,
+            "id", std::to_string(field->number()));
+      }
+      stub_h_->Outdent();
+      stub_h_->Print("};\n");
+    }
+
+    // Field descriptors.
     for (int i = 0; i < message->field_count(); ++i) {
       const FieldDescriptor* field = message->field(i);
       if (field->is_packed()) {
         Abort("Packed repeated fields are not supported.");
         return;
       }
       if (field->type() != FieldDescriptor::TYPE_MESSAGE) {
         GenerateSimpleFieldDescriptor(field);
       } else {
         GenerateNestedMessageFieldDescriptor(field);
@@ skipping 54 matching lines @@
   GeneratorJob job(file, &stub_h_printer, &stub_cc_printer);
   if (!job.GenerateStubs()) {
     *error = job.GetFirstError();
     return false;
   }
   return true;
 }
 
 }  // namespace proto
 }  // namespace tracing