Hello Wei,
On Apr 20, 2011, at 7:09 AM, Wei wrote:
> Hi, all,
>
> I have made a patch to make clang::PPCallbacks::If() &
> clang::PPCallbacks::Elif() can pass-back a token tree.
> That's what the original FIXME of these 2 functions said: "better to pass in
> a list (or tree!) of Tokens."
>
> This patch has passed all the expected tests in the clang-test. (I use Visual
> C++ 2010 Express as my dev. environment)
> 1> Testing Time: 738.14s
> 1> Expected Passes : 2877
> 1> Expected Failures : 26
> 1> Unsupported Tests : 5
>
> I hope this patch can be merged into clang main trunk, and if you have any
> problems about this patch, please let me know, I'll modify it so that it can
> be merged.
The preprocessor is an extremely performance-sensitive part of Clang, so we
need to be very careful about what computation we perform. Building a tree-like
data structure such as
@@ -264,6 +266,57 @@
};
+class TokenTreeNode {
+ private:
+ llvm::BumpPtrAllocator *Allocator;
+ Token Self;
+
+ typedef llvm::SmallVector<TokenTreeNode*,3> ChildrenTy;
+ typedef ChildrenTy::iterator iterator;
+
+ ChildrenTy Children;
+
+ public:
+ TokenTreeNode(Token &token, llvm::BumpPtrAllocator *allocator) :
+ Allocator(allocator),
+ Self(token) {
+ assert(Allocator != 0);
+ }
+
+ ~TokenTreeNode() {
+ for (iterator iter = Children.begin(); iter != Children.end(); ++iter) {
+ (*iter)->~TokenTreeNode();
+ Allocator->Deallocate(*iter);
+ }
+ }
+
+ inline ChildrenTy &getChildren() {
+ return Children;
+ }
+
+ void addChildren(iterator I, Token &T) {
+ TokenTreeNode *Node = Allocator->Allocate<TokenTreeNode>();
+ new (Node) TokenTreeNode(T, Allocator);
+ Children.insert(I, Node);
+ }
+
+ void addChildren(iterator I, TokenTreeNode *N) {
+ assert(N != 0);
+ Children.insert(I, N);
+ }
+
+ inline void addChildren(Token &T) {
+ addChildren(Children.end(), T);
+ }
+
+ inline void addChildren(TokenTreeNode *N) {
+ assert(N != 0);
+ addChildren(Children.end(), N);
+ }
+
+ void dump(unsigned IndentLevel);
+};
is likely to incur an unacceptable performance penalty. It's probably
reasonable to pass the SourceRange of the expression down to If/ElIf, from
which one could re-lex the tokens if desired.
- Doug
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