[gentoo-commits] proj/libbash:master commit in: bashast/

[Petteri Räty]

commit:     cab98c13280a953bc5cedb911dae493b74c8093c
Author:     Mu Qiao <qiaomuf <AT> gentoo <DOT> org>
AuthorDate: Sun Apr 24 12:28:21 2011 +0000
Commit:     Petteri Räty <betelgeuse <AT> gentoo <DOT> org>
CommitDate: Mon Apr 25 10:07:50 2011 +0000
URL:        http://git.overlays.gentoo.org/gitweb/?p=proj/libbash.git;a=commit;h=cab98c13

Walker: change the implementation of index searching

We used recursive counting algorithm to find the index of LT(2).
Now it's changed to recurrence algorithm that directly traverse the
input stream. This can benefit function definition and compound
command.

---
 bashast/libbashWalker.g |   40 ++++++++++++++++++++--------------------
 1 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/bashast/libbashWalker.g b/bashast/libbashWalker.g
index b6123d9..a3bf40d 100644
--- a/bashast/libbashWalker.g
+++ b/bashast/libbashWalker.g
@@ -64,24 +64,27 @@ options
 		index = value;
 	}
 
-	// Recursively count number of nodes of curr
-	static int count_nodes(pANTLR3_BASE_TREE_ADAPTOR adaptor, pANTLR3_BASE_TREE curr)
+	// seek to LT(2) and consume
+	static void seek_to_next_tree(plibbashWalker ctx)
 	{
-		int child_count = adaptor->getChildCount(adaptor, curr);
-		if(child_count == 0)
-		{
-			// Leaf node
-			return 1;
-		}
-		else
+		// We start from LA(1)
+		int index = 1;
+		// Current depth of the tree we are traversing
+		int depth = 1;
+
+		for(index = 1; depth != 0; ++index)
 		{
-			int result = 0;
-			// Count every child
-			for(int i = 0; i != child_count; ++i)
-				result += count_nodes(adaptor, (pANTLR3_BASE_TREE)(adaptor->getChild(adaptor, curr, i)));
-			// Add itself, DOWN and UP
-			return result + 3;
+			// Go one level done if we encounter DOWN
+			if(LA(index) == DOWN)
+				++depth;
+			// Go one level up if we encounter UP. When depth==0, we finishe one node
+			else if(LA(index) == UP)
+				--depth;
 		}
+
+		// Seek to the correct offset and consume.
+		SEEK(INDEX() + index - 3);
+		CONSUME();
 	}
 
 }
@@ -324,11 +327,8 @@ function_def returns[int placeholder]
 	:^(FUNCTION ^(STRING name) {
 		// Define the function with current index
 		walker->define_function($name.libbash_value, INDEX());
-		// Skip the AST for function body, minus one is needed to make the offset right.
-		// LT(1) is the function body. It should match the compound_command rule.
-		SEEK(INDEX() + count_nodes(ADAPTOR, LT(1)) - 1);
-		// After seeking ahead, we need to call CONSUME to eat all the nodes we've skipped.
-		CONSUME();
+		// Skip the AST for function body
+		seek_to_next_tree(ctx);
 	});
 
 // Only used in arithmetic expansion