[clang-doc] integrate the JSON generator with Mustache templates

This patch changes the HTML Mustache generator to use the JSON generator
and consume its output to generate its templates.

Author: evelez7

clang-tools-extra/clang-doc/BitcodeReader.cpp

@@ -384,6 +384,8 @@ static llvm::Error parseRecord(const Record &R, unsigned ID,
     return decodeRecord(R, I->Path, Blob);
   case REFERENCE_FIELD:
     return decodeRecord(R, F, Blob);
+  case REFERENCE_FILE:
+    return decodeRecord(R, I->DocumentationFileName, Blob);
   default:
     return llvm::createStringError(llvm::inconvertibleErrorCode(),
                                    "invalid field for Reference");

clang-tools-extra/clang-doc/BitcodeWriter.cpp

@@ -210,6 +210,7 @@ static const llvm::IndexedMap<RecordIdDsc, RecordIdToIndexFunctor>
           {REFERENCE_TYPE, {"RefType", &genIntAbbrev}},
           {REFERENCE_PATH, {"Path", &genStringAbbrev}},
           {REFERENCE_FIELD, {"Field", &genIntAbbrev}},
+          {REFERENCE_FILE, {"File", &genStringAbbrev}},
           {TEMPLATE_PARAM_CONTENTS, {"Contents", &genStringAbbrev}},
           {TEMPLATE_SPECIALIZATION_OF,
            {"SpecializationOf", &genSymbolIdAbbrev}},
@@ -286,7 +287,7 @@ static const std::vector<std::pair<BlockId, std::vector<RecordId>>>
         // Reference Block
         {BI_REFERENCE_BLOCK_ID,
          {REFERENCE_USR, REFERENCE_NAME, REFERENCE_QUAL_NAME, REFERENCE_TYPE,
-          REFERENCE_PATH, REFERENCE_FIELD}},
+          REFERENCE_PATH, REFERENCE_FIELD, REFERENCE_FILE}},
         // Template Blocks.
         {BI_TEMPLATE_BLOCK_ID, {}},
         {BI_TEMPLATE_PARAM_BLOCK_ID, {TEMPLATE_PARAM_CONTENTS}},
@@ -479,6 +480,7 @@ void ClangDocBitcodeWriter::emitBlock(const Reference &R, FieldId Field) {
   emitRecord((unsigned)R.RefType, REFERENCE_TYPE);
   emitRecord(R.Path, REFERENCE_PATH);
   emitRecord((unsigned)Field, REFERENCE_FIELD);
+  emitRecord(R.DocumentationFileName, REFERENCE_FILE);
 }
 
 void ClangDocBitcodeWriter::emitBlock(const FriendInfo &R) {

clang-tools-extra/clang-doc/BitcodeWriter.h

@@ -140,6 +140,7 @@ enum RecordId {
   REFERENCE_TYPE,
   REFERENCE_PATH,
   REFERENCE_FIELD,
+  REFERENCE_FILE,
   TEMPLATE_PARAM_CONTENTS,
   TEMPLATE_SPECIALIZATION_OF,
   TYPEDEF_USR,