From a518e9f639eb2e40c17b18b7b60ebac0973855fb Mon Sep 17 00:00:00 2001
From: Denis Rouzaud <denis.rouzaud@gmail.com>
Date: Thu, 11 Dec 2014 14:04:44 +0100
Subject: [PATCH] [fix #11475] expressions: add left and right associavity for
 dump of binary operators

complete test for left associativity
---
 python/core/qgsexpression.sip        |  2 +
 src/core/qgsexpression.cpp           | 76 +++++++++++++++++++++++++++-
 src/core/qgsexpression.h             |  2 +
 tests/src/core/testqgsexpression.cpp |  3 ++
 4 files changed, 81 insertions(+), 2 deletions(-)

diff --git a/python/core/qgsexpression.sip b/python/core/qgsexpression.sip
index 88138a50789..9333bec3932 100644
--- a/python/core/qgsexpression.sip
+++ b/python/core/qgsexpression.sip
@@ -378,6 +378,8 @@ class QgsExpression
         virtual void accept( QgsExpression::Visitor& v ) const;
 
         int precedence() const;
+        bool leftAssociative() const;
+        bool rightAssociative() const;
     };
 
     class NodeInOperator : QgsExpression::Node
diff --git a/src/core/qgsexpression.cpp b/src/core/qgsexpression.cpp
index 92331502385..491cf56ade8 100644
--- a/src/core/qgsexpression.cpp
+++ b/src/core/qgsexpression.cpp
@@ -2540,15 +2540,87 @@ int QgsExpression::NodeBinaryOperator::precedence() const
   return -1;
 }
 
+bool QgsExpression::NodeBinaryOperator::leftAssociative() const
+{
+  // see left/right in qgsexpressionparser.yy
+  switch ( mOp )
+  {
+    case boOr:
+    case boAnd:
+    case boEQ:
+    case boNE:
+    case boLE:
+    case boGE:
+    case boLT:
+    case boGT:
+    case boRegexp:
+    case boLike:
+    case boILike:
+    case boNotLike:
+    case boNotILike:
+    case boIs:
+    case boIsNot:
+    case boPlus:
+    case boMinus:
+    case boMul:
+    case boDiv:
+    case boIntDiv:
+    case boMod:
+    case boConcat:
+      return true;
+
+    case boPow:
+      return false;
+  }
+  Q_ASSERT( 0 && "unexpected binary operator" );
+  return -1;
+}
+
+bool QgsExpression::NodeBinaryOperator::rightAssociative() const
+{
+  // see left/right in qgsexpressionparser.yy
+  switch ( mOp )
+  {
+    case boOr:
+    case boAnd:
+    case boEQ:
+    case boNE:
+    case boLE:
+    case boGE:
+    case boLT:
+    case boGT:
+    case boRegexp:
+    case boLike:
+    case boILike:
+    case boNotLike:
+    case boNotILike:
+    case boIs:
+    case boIsNot:
+    case boPlus:
+    case boMul:
+    case boMod:
+    case boConcat:
+    case boPow:
+      return true;
+
+    case boMinus:
+    case boDiv:
+    case boIntDiv:
+      return false;
+  }
+  Q_ASSERT( 0 && "unexpected binary operator" );
+  return -1;
+}
+
 QString QgsExpression::NodeBinaryOperator::dump() const
 {
   QgsExpression::NodeBinaryOperator *lOp = dynamic_cast<QgsExpression::NodeBinaryOperator *>( mOpLeft );
   QgsExpression::NodeBinaryOperator *rOp = dynamic_cast<QgsExpression::NodeBinaryOperator *>( mOpRight );
 
   QString fmt;
-  fmt += lOp && lOp->precedence() < precedence() ? "(%1)" : "%1";
+  fmt += lOp && ( lOp->precedence() < precedence() || !lOp->leftAssociative() ) ? "(%1)" : "%1";
   fmt += " %2 ";
-  fmt += rOp && rOp->precedence() <= precedence() ? "(%3)" : "%3";
+  fmt += rOp && ( rOp->precedence() < precedence() || !rOp->rightAssociative() ) ? "(%3)" : "%3";
 
   return fmt.arg( mOpLeft->dump() ).arg( BinaryOperatorText[mOp] ).arg( mOpRight->dump() );
 }
diff --git a/src/core/qgsexpression.h b/src/core/qgsexpression.h
index 9f1c7d69393..066569f7fec 100644
--- a/src/core/qgsexpression.h
+++ b/src/core/qgsexpression.h
@@ -513,6 +513,8 @@ class CORE_EXPORT QgsExpression
         virtual void accept( Visitor& v ) const override { v.visit( *this ); }
 
         int precedence() const;
+        bool leftAssociative() const;
+        bool rightAssociative() const;
 
       protected:
         bool compare( double diff );
diff --git a/tests/src/core/testqgsexpression.cpp b/tests/src/core/testqgsexpression.cpp
index d35936b03fe..d9882f0dd2a 100644
--- a/tests/src/core/testqgsexpression.cpp
+++ b/tests/src/core/testqgsexpression.cpp
@@ -523,6 +523,9 @@ class TestQgsExpression: public QObject
 
       QgsExpression e2( e1.dump() );
       QCOMPARE( e2.evaluate().toInt(), 21 );
+
+      QgsExpression e3( "(2^3)^2" );
+      QCOMPARE( QgsExpression( e3.dump() ).evaluate().toInt(), 64 );
     }
 
     void eval_columns()