From a046b8f93de5d89e6f57c3e5b710026d87c044b0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juan=20Mart=C3=ADn=20Sotuyo=20Dodero?= <jmsotuyo@monits.com>
Date: Thu, 13 Oct 2016 14:14:34 -0300
Subject: [PATCH 1/2] Simplify lambda parsing

 - Handle less scenarios
 - Have scenarios be defined more broadly (ie: allow more than 3 params)
 - This improves parsing performance by roughly ~10%
---
 pmd-java/etc/grammar/Java.jjt | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/pmd-java/etc/grammar/Java.jjt b/pmd-java/etc/grammar/Java.jjt
index 5b2b631c37..7588c36ce9 100644
--- a/pmd-java/etc/grammar/Java.jjt
+++ b/pmd-java/etc/grammar/Java.jjt
@@ -1,4 +1,8 @@
 /**
+ * Improve lambda detection in PrimaryPrefix to improve parsing performance.
+ *
+ * Juan Martin Sotuyo Dodero 10/2016
+ *====================================================================
  * Fix for an expression within an additive expression that was
  * wrongly taken as a cast expression.
  * Bug #1484
@@ -1809,12 +1813,9 @@ void PrimaryPrefix() :
 | LOOKAHEAD(2) "this" {jjtThis.setUsesThisModifier();}
 | "super" {jjtThis.setUsesSuperModifier();}
 | LOOKAHEAD( "(" ")" "->" ) LambdaExpression()
-| LOOKAHEAD( <IDENTIFIER> "->" ) LambdaExpression()
-| LOOKAHEAD( "(" VariableDeclaratorId() ")" "->" ) LambdaExpression()
-| LOOKAHEAD( "(" VariableDeclaratorId() "," VariableDeclaratorId() ["," VariableDeclaratorId()] ")" "->" ) LambdaExpression()
-| LOOKAHEAD( "(" FormalParameter() ")" "->" ) LambdaExpression()
-| LOOKAHEAD( "(" FormalParameter() "," FormalParameter() ["," FormalParameter() ] ")" "->" ) LambdaExpression()
-| LOOKAHEAD( LambdaExpression() ) LambdaExpression()
+| LOOKAHEAD( VariableDeclaratorId() "->" ) LambdaExpression()
+| LOOKAHEAD( "(" VariableDeclaratorId() ( "," VariableDeclaratorId() )* ")" "->" ) LambdaExpression()
+| LOOKAHEAD( FormalParameters() "->" ) LambdaExpression()
 | LOOKAHEAD(3) "(" Expression() ")"
 | AllocationExpression()
 | LOOKAHEAD( ResultType() "." "class" ) ResultType() "." "class"

From 478ed3463c1563c6eecce1ed629fa8fc547dd1a1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juan=20Mart=C3=ADn=20Sotuyo=20Dodero?= <jmsotuyo@monits.com>
Date: Fri, 14 Oct 2016 09:24:06 -0300
Subject: [PATCH 2/2] Simplify lambda pursing even further

 - Remove a redundant case
 - Restrict grammar according to spec with a simpler scenario
---
 pmd-java/etc/grammar/Java.jjt | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/pmd-java/etc/grammar/Java.jjt b/pmd-java/etc/grammar/Java.jjt
index 7588c36ce9..65f9f91c4f 100644
--- a/pmd-java/etc/grammar/Java.jjt
+++ b/pmd-java/etc/grammar/Java.jjt
@@ -1812,8 +1812,7 @@ void PrimaryPrefix() :
   Literal()
 | LOOKAHEAD(2) "this" {jjtThis.setUsesThisModifier();}
 | "super" {jjtThis.setUsesSuperModifier();}
-| LOOKAHEAD( "(" ")" "->" ) LambdaExpression()
-| LOOKAHEAD( VariableDeclaratorId() "->" ) LambdaExpression()
+| LOOKAHEAD( <IDENTIFIER> "->" ) LambdaExpression()
 | LOOKAHEAD( "(" VariableDeclaratorId() ( "," VariableDeclaratorId() )* ")" "->" ) LambdaExpression()
 | LOOKAHEAD( FormalParameters() "->" ) LambdaExpression()
 | LOOKAHEAD(3) "(" Expression() ")"