Add preload option to clang-query

[steveire]

Summary

This allows loading a file with pre-defined let commands for example.

[klimek]

LG

clang-query/tool/ClangQuery.cpp

static cl::list<std::string> Commands("c", cl::desc("Specify command to run"),
                                       cl::value_desc("command"),
                                       cl::cat(ClangQueryCategory));
 
 static cl::list<std::string> CommandFiles("f",
                                           cl::desc("Read commands from file"),
                                           cl::value_desc("file"),
                                           cl::cat(ClangQueryCategory));
 
+static cl::opt<std::string> PreloadFile(
+    "preload",
+    cl::desc("Preload commands from file and start interactive mode"),
+    cl::value_desc("file"), cl::cat(ClangQueryCategory));
+
 int runCommandsInFile(const char* exeName, std::string const& fileName, QuerySession& QS)
 {
     std::ifstream Input(fileName.c_str());
     if (!Input.is_open()) {
       llvm::errs() << exeName << ": cannot open " << fileName << "\n";
       return 1;
     }
     while (Input.good()) {
int main(int argc, const char **argv) {
 
   CommonOptionsParser OptionsParser(argc, argv, ClangQueryCategory);
 
   if (!Commands.empty() && !CommandFiles.empty()) {
     llvm::errs() << argv[0] << ": cannot specify both -c and -f\n";
     return 1;
   }
 
+  if ((!Commands.empty() || !CommandFiles.empty()) && !PreloadFile.empty()) {
+    llvm::errs() << argv[0]
+                 << ": cannot specify both -c or -f with --preload\n";
+    return 1;
+  }
+
   ClangTool Tool(OptionsParser.getCompilations(),
                  OptionsParser.getSourcePathList());
   std::vector<std::unique_ptr<ASTUnit>> ASTs;
   if (Tool.buildASTs(ASTs) != 0)
     return 1;
 
   QuerySession QS(ASTs);
 
   if (!Commands.empty()) {
     for (auto I = Commands.begin(), E = Commands.end(); I != E; ++I) {
       QueryRef Q = QueryParser::parse(*I, QS);
       if (!Q->run(llvm::outs(), QS))
         return 1;
     }
   } else if (!CommandFiles.empty()) {
     for (auto I = CommandFiles.begin(), E = CommandFiles.end(); I != E; ++I) {
       if (auto err = runCommandsInFile(argv[0], *I, QS))
         return err;
     }
   } else {
+    if (!PreloadFile.empty()) {
+      if (auto err = runCommandsInFile(argv[0], PreloadFile, QS))
+        return err;
+    }
     LineEditor LE("clang-query");
     LE.setListCompleter([&QS](StringRef Line, size_t Pos) {
       return QueryParser::complete(Line, Pos, QS);
     });
     while (llvm::Optional<std::string> Line = LE.readLine()) {
       QueryRef Q = QueryParser::parse(*Line, QS);
       Q->run(llvm::outs(), QS);
       llvm::outs().flush();
       if (QS.Terminate)
         break;
     }
   }
 
   return 0;
 }