cleaned up TemplateParameterManager a bit

2 files changed, 48 insertions, 45 deletions

diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/GNUCPPSourceParser.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/GNUCPPSourceParser.java
index 047110410fd..48f2efbb731 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/GNUCPPSourceParser.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/GNUCPPSourceParser.java
@@ -175,7 +175,7 @@ public class GNUCPPSourceParser extends AbstractGNUSourceCodeParser {
 
     protected CPPASTTranslationUnit translationUnit;
     
-    private static class ScopeStack {
+    private final static class ScopeStack {
         private int[] stack;
 
         private int index = -1;
@@ -190,27 +190,28 @@ public class GNUCPPSourceParser extends AbstractGNUSourceCodeParser {
             stack = newStack;
         }
 
-        final public void push(int i) {
+        public void push(int i) {
             if (++index == stack.length)
                 grow();
             stack[index] = i;
         }
 
-        final public int pop() {
+        public int pop() {
             if (index >= 0)
                 return stack[index--];
             return -1;
         }
 
-        final public int peek() {
+        public int peek() {
             if (index >= 0)
                 return stack[index];
             return -1;
         }
 
-        final public int size() {
+        public int size() {
             return index + 1;
         }
+        
     }
 
     /**
@@ -822,8 +823,7 @@ public class GNUCPPSourceParser extends AbstractGNUSourceCodeParser {
      * @param expression
      * @throws BacktrackException
      */
-    protected IASTExpression multiplicativeExpression()
-            throws BacktrackException, EndOfFileException {
+    protected IASTExpression multiplicativeExpression() throws BacktrackException, EndOfFileException {
         IASTExpression firstExpression = pmExpression();
         for (;;) {
             switch (LT(1)) {
@@ -858,8 +858,7 @@ public class GNUCPPSourceParser extends AbstractGNUSourceCodeParser {
      * @param expression
      * @throws BacktrackException
      */
-    protected IASTExpression pmExpression() throws EndOfFileException,
-            BacktrackException {
+    protected IASTExpression pmExpression() throws EndOfFileException, BacktrackException {
 
         IASTExpression firstExpression = castExpression();
         for (;;) {
@@ -890,15 +889,16 @@ public class GNUCPPSourceParser extends AbstractGNUSourceCodeParser {
     /**
      * castExpression : unaryExpression | "(" typeId ")" castExpression
      */
-    protected IASTExpression castExpression() throws EndOfFileException,
-    				BacktrackException {
+    protected IASTExpression castExpression() throws EndOfFileException, BacktrackException {
 // 		TO DO: we need proper symbol checkint to ensure type name
     	if (LT(1) == IToken.tLPAREN) {
     		IToken la = LA(1);
     		int startingOffset = la.getOffset();
     		IToken mark = mark();
     		consume();
-    		if (templateIdScopes.size() > 0) { templateIdScopes.push(IToken.tLPAREN); }
+    		
+    		if (templateIdScopes.size() > 0)  
+    			templateIdScopes.push(IToken.tLPAREN); 
     		
     		boolean popped = false;
     		IASTTypeId typeId = null;
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/TemplateParameterManager.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/TemplateParameterManager.java
index 9efa9fd8081..b97c2626f31 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/TemplateParameterManager.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/TemplateParameterManager.java
@@ -14,66 +14,72 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
+import org.eclipse.cdt.core.dom.ast.IASTNode;
 
-public final class TemplateParameterManager
-{	
-	protected void reset()
-	{
-		list = Collections.EMPTY_LIST;
+/**
+ * Manages lists of template parameter nodes during the parsing
+ * of names. The purpose of this class is performance, as these
+ * lists are managed using lazy initialization and object pooling.
+ * This class is basically as substitute for List<List<IASTNode>>.
+ * 
+ * When using the object pool code must be wrapped in a try-finally
+ * block to ensure the object is returned to the pool.
+ * 
+ * TODO: How much of a performance improvement are we talking about here?
+ * It might make sense just to get rid of this class. The extra complexity
+ * might not be worth it.
+ */
+public final class TemplateParameterManager {
+	
+	protected void reset() {
+		list = Collections.emptyList();
 		emptySegmentCount = 0;
 	}
 	
-	private TemplateParameterManager(int i)
-	{
+	private TemplateParameterManager(int i) {
 		reset();
 		counterId = i;
 	}
 	
 	private final int counterId;
-	private List list;
+	private List<List<IASTNode>> list;
 	private int emptySegmentCount;
 
-	public List getTemplateArgumentsList()
-	{
+	public List<List<IASTNode>> getTemplateArgumentsList() {
 		return list;
 	}
 	
-	public void addSegment( List inputSegment )
-	{
-		if( inputSegment == null )
-		{
-			if( list == Collections.EMPTY_LIST )
+	public void addSegment(List<IASTNode> inputSegment) {
+		// avoid creating an actual ArrayList instance for as long as possible
+		if(inputSegment == null) {
+			if(list.isEmpty())
 				++emptySegmentCount;
 			else
 				list.add( null );
 		}
-		else
-		{
-			if( list == Collections.EMPTY_LIST )
-			{
-				list = new ArrayList();
+		else {
+			if(list.isEmpty()) {
+				list = new ArrayList<List<IASTNode>>();
 				for( int i = 0; i < emptySegmentCount; ++i )
 					list.add( null );
 			}
 			list.add( inputSegment );
 		}
 	}
+	
+	
+	// An object pool
 
 	private static final int NUMBER_OF_INSTANCES = 8;
 	private static final boolean [] instancesUsed = new boolean[ NUMBER_OF_INSTANCES ];
 	private static final TemplateParameterManager [] counters = new TemplateParameterManager[ NUMBER_OF_INSTANCES ];
 	private static int counter = 8;
-	static
-	{
-		for( int i = 0; i < NUMBER_OF_INSTANCES; ++i )
-		{
-			instancesUsed[ i ] = false;
+	static {
+		for( int i = 0; i < NUMBER_OF_INSTANCES; ++i ) {
 			counters[ i ] = new TemplateParameterManager( i );
 		}
 	}
-	/**
-	 * @return
-	 */
+
 	public synchronized static TemplateParameterManager getInstance() {
 		int index = findFreeCounter();
 		if( index == -1 )
@@ -82,16 +88,13 @@ public final class TemplateParameterManager
 		return counters[ index ];
 	}
 
-	public synchronized static void returnInstance( TemplateParameterManager c )
-	{
+	public synchronized static void returnInstance( TemplateParameterManager c ) {
 		if( c.counterId > 0 && c.counterId < NUMBER_OF_INSTANCES )
 			instancesUsed[ c.counterId ] = false;
 		c.reset();
 	}
 	
-	/**
-	 * @return
-	 */
+	
 	private static int findFreeCounter() {
 		for( int i = 0; i < NUMBER_OF_INSTANCES; ++i )
 			if( instancesUsed[i] == false )