Tracing V2: Field number constants for protobuf plugin.

components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc

Index: components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc
diff --git a/components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc b/components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc
index 2165673b362eeefc3bbb110ca2e0be0fa6aac01c..055cbe759dda51227492034c18fdb1919a2dbb44 100644
--- a/components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc
+++ b/components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc
@@ -26,6 +26,7 @@ using google::protobuf::compiler::GeneratorContext;
 using google::protobuf::io::Printer;
 using google::protobuf::io::ZeroCopyOutputStream;
 
+using google::protobuf::LowerString;
 using google::protobuf::Split;
 using google::protobuf::StripPrefixString;
 using google::protobuf::StripString;
@@ -38,6 +39,93 @@ inline std::string ProtoStubName(const FileDescriptor* proto) {
   return StripSuffixString(proto->name(), ".proto") + ".pbzero";
 }
 
+enum CharCase {
+  UPPER,
+  LOWER,
+  DIGIT,
+  SYMBOL,
+  UNDEFINED,
+};
+
+inline CharCase GetCaseOfChar(char x) {
+  if ('A' <= x && x <= 'Z')
+    return CharCase::UPPER;

[Primiano Tucci (use gerrit), 2016/08/05 08:52:05]

I think here you are reinventing cctype's isupper(), isalpha(), isdigit() etc.

[kraynov, 2016/08/05 11:05:53]

Acknowledged.

+  else if ('a' <= x && x <= 'z')
+    return CharCase::LOWER;
+  else if ('0' <= x && x <= '9')
+    return CharCase::DIGIT;
+  else
+    return CharCase::SYMBOL;
+}
+
+std::string ExtractWord(const std::string& source, size_t* offset) {
+  std::string word;
+  CharCase start_case = CharCase::UNDEFINED;
+  CharCase end_case = CharCase::UNDEFINED;
+
+  while (*offset < source.size()) {
+    char current = source.at(*offset);
+    CharCase current_case = GetCaseOfChar(current);
+
+    // Skip underscores.
+    if (current_case == CharCase::SYMBOL) {
+      while (current_case == CharCase::SYMBOL) {
+        (*offset)++;
+        if (*offset == source.size())
+          return word;
+        current = source.at(*offset);
+        current_case = GetCaseOfChar(current);
+      }
+      if (!word.empty())
+        return word;
+    }
+    // Current case must be UPPER, LOWER or DIGIT below this line.
+
+    // Detect word's case.
+    if (word.empty()) {
+      start_case = current_case;
+      if (start_case == CharCase::LOWER || start_case == CharCase::DIGIT) {
+        end_case = start_case;
+      }
+    } else if (end_case == CharCase::UNDEFINED) {
+      // Must be a second character in this condition.
+      // Word starting with upper letter has two options (e.g. FOO or Bar).
+      end_case = current_case;
+    }
+
+    // Finish the word if case changes.
+    if (current_case != end_case && end_case != CharCase::UNDEFINED) {
+      if (end_case == CharCase::UPPER && current_case == CharCase::LOWER) {
+        // Rollback one character.
+        // E.g. [URL]Encoder, not [URLE]ncoder.
+        (*offset)--;
+        word.erase(word.size() - 1, 1);
+      }
+      return word;
+    }
+
+    word.push_back(current);
+    (*offset)++;
+  }
+  return word;
+}
+
+std::string NameToCamelCase(const std::string& name) {
+  std::string camel;
+  size_t offset = 0;
+  while (offset < name.size()) {
+    // Offset is mutable by ExtractWord function.
+    std::string word = ExtractWord(name, &offset);
+    if (word.empty())
+      continue;
+    LowerString(&word);
+    if (GetCaseOfChar(word.at(0)) == LOWER)
+      word.at(0) -= ('a' - 'A');
+    camel += word;
+  }
+  return camel;
+}
+
 class GeneratorJob {
  public:
   GeneratorJob(const FileDescriptor *file,
@@ -463,7 +551,27 @@ class GeneratorJob {
       }
     }
 
-    // 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 = NameToCamelCase(field->name());

[Primiano Tucci (use gerrit), 2016/08/05 08:52:05]

can you not just use field->camelcase_name()

[kraynov, 2016/08/05 11:05:53]

Acknowledged.

+        if (name.empty())
+          Abort("Empty field name in camel case notation.");
+
+        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()) {