Add abs function

nyalldawson · nyalldawson · commit ff92b029cfa5 · 2013-05-13T08:14:37.000+10:00
diff --git a/resources/function_help/abs-en_US b/resources/function_help/abs-en_US
@@ -0,0 +1,12 @@
+<h3>abs() function</h3>
+Returns the absolute value of a number.<br>
+
+
+<h4>Syntax</h4>
+abs(<i>value</i>)<br>
+
+<h4>Arguments</h4>
+<code>value</code> - a number.<br>
+
+<h4>Example</h4>
+<code>abs(-2) &rarr; 2</code><br>
diff --git a/src/core/qgsexpression.cpp b/src/core/qgsexpression.cpp
@@ -347,6 +347,13 @@ static QVariant fcnSqrt( const QVariantList& values, QgsFeature* /*f*/, QgsExpre
   double x = getDoubleValue( values.at( 0 ), parent );
   return QVariant( sqrt( x ) );
 }
+
+static QVariant fcnAbs( const QVariantList& values, QgsFeature*, QgsExpression* parent )
+{
+  double val = getDoubleValue( values.at( 0 ), parent );
+  return QVariant( fabs( val ) );
+}
+
 static QVariant fcnSin( const QVariantList& values, QgsFeature* , QgsExpression* parent )
 {
   double x = getDoubleValue( values.at( 0 ), parent );
@@ -1299,7 +1306,7 @@ const QStringList &QgsExpression::BuiltinFunctions()
   if ( gmBuiltinFunctions.isEmpty() )
   {
     gmBuiltinFunctions
-    << "sqrt" << "cos" << "sin" << "tan"
+    << "abs" << "sqrt" << "cos" << "sin" << "tan"
     << "asin" << "acos" << "atan" << "atan2"
     << "exp" << "ln" << "log10" << "log"
     << "round" << "rand" << "randf" << "max" << "min"
@@ -1331,6 +1338,7 @@ const QList<QgsExpression::Function*> &QgsExpression::Functions()
   {
     gmFunctions
     << new StaticFunction( "sqrt", 1, fcnSqrt, QObject::tr( "Math" ) )
+    << new StaticFunction( "abs", 1, fcnAbs, QObject::tr( "Math" ) )
     << new StaticFunction( "cos", 1, fcnCos, QObject::tr( "Math" ) )
     << new StaticFunction( "sin", 1, fcnSin, QObject::tr( "Math" ) )
     << new StaticFunction( "tan", 1, fcnTan, QObject::tr( "Math" ) )
diff --git a/tests/src/core/testqgsexpression.cpp b/tests/src/core/testqgsexpression.cpp
@@ -229,6 +229,9 @@ class TestQgsExpression: public QObject
 
       // math functions
       QTest::newRow( "sqrt" ) << "sqrt(16)" << false << QVariant( 4. );
+      QTest::newRow( "abs(0.1)" ) << "abs(0.1)" << false << QVariant( 0.1 );
+      QTest::newRow( "abs(0)" ) << "abs(0)" << false << QVariant( 0. );
+      QTest::newRow( "abs(-0.1)" ) << "abs(-0.1)" << false << QVariant( 0.1 );
       QTest::newRow( "invalid sqrt value" ) << "sqrt('a')" << true << QVariant();
       QTest::newRow( "sin 0" ) << "sin(0)" << false << QVariant( 0. );
       QTest::newRow( "cos 0" ) << "cos(0)" << false << QVariant( 1. );
