From 0672abbaed506d96ffa5f3a6d3e51109e442ec5b Mon Sep 17 00:00:00 2001
From: Nyall Dawson <nyall.dawson@gmail.com>
Date: Fri, 15 Apr 2016 05:47:47 +1000
Subject: [PATCH] [FEATURE] Compilation support for unary - operation

---
 src/core/qgssqlexpressioncompiler.cpp          | 14 +++++++++++++-
 src/core/qgssqlexpressioncompiler.h            |  1 +
 src/providers/ogr/qgsogrexpressioncompiler.cpp |  3 ++-
 tests/src/python/providertestbase.py           |  5 +++++
 tests/src/python/test_provider_shapefile.py    |  7 ++++++-
 5 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/src/core/qgssqlexpressioncompiler.cpp b/src/core/qgssqlexpressioncompiler.cpp
index cdc4f1e2e3c..9cba8b2fe73 100644
--- a/src/core/qgssqlexpressioncompiler.cpp
+++ b/src/core/qgssqlexpressioncompiler.cpp
@@ -93,7 +93,19 @@ QgsSqlExpressionCompiler::Result QgsSqlExpressionCompiler::compileNode( const Qg
         }
 
         case QgsExpression::uoMinus:
-          break;
+        {
+          if ( mFlags.testFlag( NoUnaryMinus ) )
+            return Fail;
+
+          QString right;
+          if ( compileNode( n->operand(), right ) == Complete )
+          {
+            result = "( - (" + right + "))";
+            return Complete;
+          }
+
+          return Fail;
+        }
       }
 
       break;
diff --git a/src/core/qgssqlexpressioncompiler.h b/src/core/qgssqlexpressioncompiler.h
index 5e0da3b0902..1974217960b 100644
--- a/src/core/qgssqlexpressioncompiler.h
+++ b/src/core/qgssqlexpressioncompiler.h
@@ -50,6 +50,7 @@ class CORE_EXPORT QgsSqlExpressionCompiler
       CaseInsensitiveStringMatch = 0x01,  //!< Provider performs case-insensitive string matching for all strings
       LikeIsCaseInsensitive = 0x02, //!< Provider treats LIKE as case-insensitive
       NoNullInBooleanLogic = 0x04, //!< Provider does not support using NULL with boolean logic, eg "(...) OR NULL"
+      NoUnaryMinus = 0x08, //!< Provider does not unary minus, eg " -( 100 * 2 ) = ..."
     };
     Q_DECLARE_FLAGS( Flags, Flag )
 
diff --git a/src/providers/ogr/qgsogrexpressioncompiler.cpp b/src/providers/ogr/qgsogrexpressioncompiler.cpp
index db88da24e9f..8baac96ce01 100644
--- a/src/providers/ogr/qgsogrexpressioncompiler.cpp
+++ b/src/providers/ogr/qgsogrexpressioncompiler.cpp
@@ -17,7 +17,8 @@
 #include "qgsogrprovider.h"
 
 QgsOgrExpressionCompiler::QgsOgrExpressionCompiler( QgsOgrFeatureSource* source )
-    : QgsSqlExpressionCompiler( source->mFields, QgsSqlExpressionCompiler::CaseInsensitiveStringMatch | QgsSqlExpressionCompiler::NoNullInBooleanLogic )
+    : QgsSqlExpressionCompiler( source->mFields, QgsSqlExpressionCompiler::CaseInsensitiveStringMatch | QgsSqlExpressionCompiler::NoNullInBooleanLogic
+                                | QgsSqlExpressionCompiler::NoUnaryMinus )
     , mSource( source )
 {
 }
diff --git a/tests/src/python/providertestbase.py b/tests/src/python/providertestbase.py
index a3eb06558fc..2f4e2c20885 100644
--- a/tests/src/python/providertestbase.py
+++ b/tests/src/python/providertestbase.py
@@ -119,7 +119,9 @@ class ProviderTestCase(object):
         self.assert_query(provider, 'name ILIKE \'aPple\'', [2])
         self.assert_query(provider, 'name ILIKE \'%pp%\'', [2])
         self.assert_query(provider, 'cnt > 0', [1, 2, 3, 4])
+        self.assert_query(provider, '-cnt > 0', [5])
         self.assert_query(provider, 'cnt < 0', [5])
+        self.assert_query(provider, '-cnt < 0', [1, 2, 3, 4])
         self.assert_query(provider, 'cnt >= 100', [1, 2, 3, 4])
         self.assert_query(provider, 'cnt <= 100', [1, 5])
         self.assert_query(provider, 'pk IN (1, 2, 4, 8)', [1, 2, 4])
@@ -127,6 +129,9 @@ class ProviderTestCase(object):
         self.assert_query(provider, 'cnt = 99 + 1', [1])
         self.assert_query(provider, 'cnt = 101 - 1', [1])
         self.assert_query(provider, 'cnt - 1 = 99', [1])
+        self.assert_query(provider, '-cnt - 1 = -101', [1])
+        self.assert_query(provider, '-(-cnt) = 100', [1])
+        self.assert_query(provider, '-(cnt) = -(100)', [1])
         self.assert_query(provider, 'cnt + 1 = 101', [1])
         self.assert_query(provider, 'cnt = 1100 % 1000', [1])
         self.assert_query(provider, '"name" || \' \' || "name" = \'Orange Orange\'', [1])
diff --git a/tests/src/python/test_provider_shapefile.py b/tests/src/python/test_provider_shapefile.py
index a6e70a7c163..aafaaece04b 100644
--- a/tests/src/python/test_provider_shapefile.py
+++ b/tests/src/python/test_provider_shapefile.py
@@ -99,7 +99,12 @@ class TestPyQgsShapefileProvider(unittest.TestCase, ProviderTestCase):
                     'not name = \'Apple\' or not name = \'Apple\'',
                     'not name = \'Apple\' and pk = 4',
                     'not name = \'Apple\' and not pk = 4',
-                    'num_char IN (2, 4, 5)'])
+                    'num_char IN (2, 4, 5)',
+                    '-cnt > 0',
+                    '-cnt < 0',
+                    '-cnt - 1 = -101',
+                    '-(-cnt) = 100',
+                    '-(cnt) = -(100)'])
 
     def partiallyCompiledFilters(self):
         return set(['name = \'Apple\'',