svn commit: r1292239 - /cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/src/main/java/org/apache/cayenne/exp/Expression.java

[aadamchik]

Author: aadamchik
Date: Wed Feb 22 11:17:45 2012
New Revision: 1292239

URL: http://svn.apache.org/viewvc?rev=1292239&view=rev
Log:
CAY-1667 Expression parser performance optimization

avoid wasting memory on processing buffers larger than the input

Modified:
    
cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/src/main/java/org/apache/cayenne/exp/Expression.java

Modified: 
cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/src/main/java/org/apache/cayenne/exp/Expression.java
URL: 
http://svn.apache.org/viewvc/cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/src/main/java/org/apache/cayenne/exp/Expression.java?rev=1292239&r1=1292238&r2=1292239&view=diff
==============================================================================
--- 
cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/src/main/java/org/apache/cayenne/exp/Expression.java
 (original)
+++ 
cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/src/main/java/org/apache/cayenne/exp/Expression.java
 Wed Feb 22 11:17:45 2012
@@ -32,6 +32,8 @@ import java.util.Map;
 
 import org.apache.cayenne.exp.parser.ASTScalar;
 import org.apache.cayenne.exp.parser.ExpressionParser;
+import org.apache.cayenne.exp.parser.ExpressionParserTokenManager;
+import org.apache.cayenne.exp.parser.JavaCharStream;
 import org.apache.cayenne.exp.parser.ParseException;
 import org.apache.cayenne.util.ConversionUtil;
 import org.apache.cayenne.util.Util;
@@ -117,6 +119,9 @@ public abstract class Expression impleme
     public static final int NOT_LIKE = 37;
     public static final int NOT_LIKE_IGNORE_CASE = 38;
 
+    
+    private static final int PARSE_BUFFER_MAX_SIZE = 4096;
+    
     protected int type;
 
     /**
@@ -131,9 +136,17 @@ public abstract class Expression impleme
             throw new NullPointerException("Null expression string.");
         }
 
+        // optimizing parser buffers per CAY-1667...
+        int bufferSize = expressionString.length() > PARSE_BUFFER_MAX_SIZE
+                ? PARSE_BUFFER_MAX_SIZE
+                : expressionString.length();
         Reader reader = new StringReader(expressionString);
+        JavaCharStream stream = new JavaCharStream(reader, 1, 1, bufferSize);
+        ExpressionParserTokenManager tm = new 
ExpressionParserTokenManager(stream);
+        ExpressionParser parser = new ExpressionParser(tm);
+
         try {
-            return new ExpressionParser(reader).expression();
+            return parser.expression();
         }
         catch (ParseException ex) {
             throw new ExpressionException(ex.getMessage(), ex);