[clang-scan-deps] NFC, refactor the DependencyScanningWorker to use a consumer

to report the dependencies to the client

This will allow the scanner to report modular dependencies to the consumer.
This will also allow the scanner to accept regular cc1 clang invocations, e.g.
in an implementation of a libclang C API for clang-scan-deps, that I will add
follow-up patches for in the future.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@370425 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 57 insertions, 1 deletions

diff --git a/tools/clang-scan-deps/ClangScanDeps.cpp b/tools/clang-scan-deps/ClangScanDeps.cpp
index 5e567fef9d..bee4b479b2 100644
--- a/tools/clang-scan-deps/ClangScanDeps.cpp
+++ b/tools/clang-scan-deps/ClangScanDeps.cpp
@@ -51,11 +51,67 @@ public:
                          SharedStream &OS, SharedStream &Errs)
       : Worker(Service), Compilations(Compilations), OS(OS), Errs(Errs) {}
 
+  /// Print out the dependency information into a string using the dependency
+  /// file format that is specified in the options (-MD is the default) and
+  /// return it.
+  ///
+  /// \returns A \c StringError with the diagnostic output if clang errors
+  /// occurred, dependency file contents otherwise.
+  llvm::Expected<std::string> getDependencyFile(const std::string &Input,
+                                                StringRef CWD) {
+    /// Prints out all of the gathered dependencies into a string.
+    class DependencyPrinterConsumer : public DependencyConsumer {
+    public:
+      void handleFileDependency(const DependencyOutputOptions &Opts,
+                                StringRef File) override {
+        if (!this->Opts)
+          this->Opts = std::make_unique<DependencyOutputOptions>(Opts);
+        Dependencies.push_back(File);
+      }
+
+      void printDependencies(std::string &S) {
+        if (!Opts)
+          return;
+
+        class DependencyPrinter : public DependencyFileGenerator {
+        public:
+          DependencyPrinter(DependencyOutputOptions &Opts,
+                            ArrayRef<std::string> Dependencies)
+              : DependencyFileGenerator(Opts) {
+            for (const auto &Dep : Dependencies)
+              addDependency(Dep);
+          }
+
+          void printDependencies(std::string &S) {
+            llvm::raw_string_ostream OS(S);
+            outputDependencyFile(OS);
+          }
+        };
+
+        DependencyPrinter Generator(*Opts, Dependencies);
+        Generator.printDependencies(S);
+      }
+
+    private:
+      std::unique_ptr<DependencyOutputOptions> Opts;
+      std::vector<std::string> Dependencies;
+    };
+
+    DependencyPrinterConsumer Consumer;
+    auto Result =
+        Worker.computeDependencies(Input, CWD, Compilations, Consumer);
+    if (Result)
+      return std::move(Result);
+    std::string Output;
+    Consumer.printDependencies(Output);
+    return Output;
+  }
+
   /// Computes the dependencies for the given file and prints them out.
   ///
   /// \returns True on error.
   bool runOnFile(const std::string &Input, StringRef CWD) {
-    auto MaybeFile = Worker.getDependencyFile(Input, CWD, Compilations);
+    auto MaybeFile = getDependencyFile(Input, CWD);
     if (!MaybeFile) {
       llvm::handleAllErrors(
           MaybeFile.takeError(), [this, &Input](llvm::StringError &Err) {