[clang-diff] NFC: organise header

include/clang/Tooling/ASTDiff/ASTDiff.h

enum ChangeKind {
   Update,    // (Src, Dst): update the value of node Src to match Dst.
   Insert,    // (Src, Dst, Pos): insert Src as child of Dst at offset Pos.
   Move,      // (Src, Dst, Pos): move Src to be a child of Dst at offset Pos.
   UpdateMove // Same as Move plus Update.
 };
 
 using NodeRef = const Node &;
 
+struct ComparisonOptions {
+  /// During top-down matching, only consider nodes of at least this height.
+  int MinHeight = 2;
+
+  /// During bottom-up matching, match only nodes with at least this value as
+  /// the ratio of their common descendants.
+  double MinSimilarity = 0.5;
+
+  /// Whenever two subtrees are matched in the bottom-up phase, the optimal
+  /// mapping is computed, unless the size of either subtrees exceeds this.
+  int MaxSize = 100;
+
+  bool StopAfterTopDown = false;
+
+  /// Returns false if the nodes should never be matched.
+  bool isMatchingAllowed(NodeRef N1, NodeRef N2) const;
+};
+
 class ASTDiff {
 public:
   ASTDiff(SyntaxTree &Src, SyntaxTree &Dst, const ComparisonOptions &Options);
   ~ASTDiff();
 
   const Node *getMapped(NodeRef N) const;
 
   class Impl;
struct NodeRefIterator {
   NodeRefIterator(SyntaxTree::Impl *Tree, const NodeId *IdPointer)
       : Tree(Tree), IdPointer(IdPointer) {}
   NodeRef operator*() const;
   NodeRefIterator &operator++();
   NodeRefIterator &operator+(int Offset);
   bool operator!=(const NodeRefIterator &Other) const;
 };
 
-struct ComparisonOptions {
-  /// During top-down matching, only consider nodes of at least this height.
-  int MinHeight = 2;
-
-  /// During bottom-up matching, match only nodes with at least this value as
-  /// the ratio of their common descendants.
-  double MinSimilarity = 0.5;
-
-  /// Whenever two subtrees are matched in the bottom-up phase, the optimal
-  /// mapping is computed, unless the size of either subtrees exceeds this.
-  int MaxSize = 100;
-
-  bool StopAfterTopDown = false;
-
-  /// Returns false if the nodes should never be matched.
-  bool isMatchingAllowed(NodeRef N1, NodeRef N2) const {
-    return N1.getType().isSame(N2.getType());
-  }
-};
-
 } // end namespace diff
 } // end namespace clang
 
 #endif

lib/Tooling/ASTDiff/ASTDiff.cpp

 #include <unordered_set>
 
 using namespace llvm;
 using namespace clang;
 
 namespace clang {
 namespace diff {
 
+bool ComparisonOptions::isMatchingAllowed(NodeRef N1, NodeRef N2) const {
+  return N1.getType().isSame(N2.getType());
+}
+
 class ASTDiff::Impl {
 private:
   std::unique_ptr<NodeId[]> SrcToDst, DstToSrc;
 
 public:
   SyntaxTree::Impl &T1, &T2;
 
   Impl(SyntaxTree::Impl &T1, SyntaxTree::Impl &T2,