First revision of the dynamic ASTMatcher library.

This library supports all the features of the compile-time based ASTMatcher
library, but allows the user to specify and construct the matchers at runtime.
It contains the following modules:
 - A variant type, to be used by the matcher factory.
 - A registry, where the matchers are indexed by name and have a factory method
   with a generic signature.
 - A simple matcher expression parser, that can be used to convert a matcher
   expression string into actual matchers that can be used with the AST at
   runtime.

Many features where omitted from this first revision to simplify this code
review. The main ideas are still represented in this change and it already has
support working use cases.
Things that are missing:
 - Support for polymorphic matchers. These requires supporting code in the
   registry, the marshallers and the variant type.
 - Support for numbers, char and bool arguments to the matchers. This requires
   supporting code in the parser and the variant type.
 - A command line program putting everything together and providing an already
   functional tool.

Patch by Samuel Benzaquen.

llvm-svn: 181768

1 files changed, 105 insertions, 0 deletions

diff --git a/clang/lib/ASTMatchers/Dynamic/VariantValue.cpp b/clang/lib/ASTMatchers/Dynamic/VariantValue.cpp
new file mode 100644
index 00000000000..e310fbfc58f
--- /dev/null
+++ b/clang/lib/ASTMatchers/Dynamic/VariantValue.cpp
@@ -0,0 +1,105 @@
+//===--- VariantValue.cpp - Polymorphic value type -*- C++ -*-===/
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief Polymorphic value type.
+///
+//===----------------------------------------------------------------------===//
+
+#include "clang/ASTMatchers/Dynamic/VariantValue.h"
+
+namespace clang {
+namespace ast_matchers {
+namespace dynamic {
+
+VariantValue::VariantValue(const VariantValue &Other) : Type(VT_Nothing) {
+  *this = Other;
+}
+
+VariantValue::VariantValue(const DynTypedMatcher &Matcher) : Type(VT_Nothing) {
+  setMatcher(Matcher);
+}
+
+VariantValue::VariantValue(const std::string &String) : Type(VT_Nothing) {
+  setString(String);
+}
+
+VariantValue::~VariantValue() { reset(); }
+
+VariantValue &VariantValue::operator=(const VariantValue &Other) {
+  if (this == &Other) return *this;
+  reset();
+  switch (Other.Type) {
+  case VT_String:
+    setString(Other.getString());
+    break;
+  case VT_Matcher:
+    setMatcher(Other.getMatcher());
+    break;
+  case VT_Nothing:
+    Type = VT_Nothing;
+    break;
+  }
+  return *this;
+}
+
+void VariantValue::reset() {
+  switch (Type) {
+  case VT_String:
+    delete Value.String;
+    break;
+  case VT_Matcher:
+    delete Value.Matcher;
+    break;
+  // Cases that do nothing.
+  case VT_Nothing:
+    break;
+  }
+  Type = VT_Nothing;
+}
+
+bool VariantValue::isString() const {
+  return Type == VT_String;
+}
+
+const std::string &VariantValue::getString() const {
+  assert(isString());
+  return *Value.String;
+}
+
+void VariantValue::setString(const std::string &NewValue) {
+  reset();
+  Type = VT_String;
+  Value.String = new std::string(NewValue);
+}
+
+bool VariantValue::isMatcher() const {
+  return Type == VT_Matcher;
+}
+
+const DynTypedMatcher &VariantValue::getMatcher() const {
+  assert(isMatcher());
+  return *Value.Matcher;
+}
+
+void VariantValue::setMatcher(const DynTypedMatcher &NewValue) {
+  reset();
+  Type = VT_Matcher;
+  Value.Matcher = NewValue.clone();
+}
+
+void VariantValue::takeMatcher(DynTypedMatcher *NewValue) {
+  reset();
+  Type = VT_Matcher;
+  Value.Matcher = NewValue;
+}
+
+} // end namespace dynamic
+} // end namespace ast_matchers
+} // end namespace clang