Allow expression functions to include 0 length parameter lists

This change allows for some cleanups to the built in expression functions, by making it possible to differentiate variables (eg $feature) from functions which don't require parameters (eg uuid(), now()... ). Also adds aliases for uuid(), now(), and pi().
qgis · May 3, 2015 · 96db1bd · 96db1bd
1 parent bd9e02b
commit 96db1bd
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Showing 7 changed files with 25 additions and 39 deletions.
diff --git a/resources/function_help/$now b/resources/function_help/$now
diff --git a/resources/function_help/$pi b/resources/function_help/$pi
diff --git a/resources/function_help/$uuid b/resources/function_help/$uuid
diff --git a/src/core/qgsexpression.cpp b/src/core/qgsexpression.cpp
@@ -1728,7 +1728,7 @@ const QList<QgsExpression::Function*> &QgsExpression::Functions()
     << new StaticFunction( "scale_exp", 6, fcnExpScale, "Math" )
     << new StaticFunction( "floor", 1, fcnFloor, "Math" )
     << new StaticFunction( "ceil", 1, fcnCeil, "Math" )
-    << new StaticFunction( "$pi", 0, fcnPi, "Math" )
+    << new StaticFunction( "pi", 0, fcnPi, "Math", QString(), false, QStringList(), false, QStringList() << "$pi" )
     << new StaticFunction( "to_int", 1, fcnToInt, "Conversions", QString(), false, QStringList(), false, QStringList() << "toint" )
     << new StaticFunction( "to_real", 1, fcnToReal, "Conversions", QString(), false, QStringList(), false, QStringList() << "toreal" )
     << new StaticFunction( "to_string", 1, fcnToString, "Conversions", QString(), false, QStringList(), false, QStringList() << "tostring" )
@@ -1739,7 +1739,7 @@ const QList<QgsExpression::Function*> &QgsExpression::Functions()
     << new StaticFunction( "coalesce", -1, fcnCoalesce, "Conditionals" )
     << new StaticFunction( "if", 3, fcnIf, "Conditionals", "", False, QStringList(), true )
     << new StaticFunction( "regexp_match", 2, fcnRegexpMatch, "Conditionals" )
-    << new StaticFunction( "$now", 0, fcnNow, "Date and Time" )
+    << new StaticFunction( "now", 0, fcnNow, "Date and Time", QString(), false, QStringList(), false, QStringList() << "$now" )
     << new StaticFunction( "age", 2, fcnAge, "Date and Time" )
     << new StaticFunction( "year", 1, fcnYear, "Date and Time" )
     << new StaticFunction( "month", 1, fcnMonth, "Date and Time" )
@@ -1817,7 +1817,7 @@ const QList<QgsExpression::Function*> &QgsExpression::Functions()
     << new StaticFunction( "$id", 0, fcnFeatureId, "Record" )
     << new StaticFunction( "$currentfeature", 0, fcnFeature, "Record" )
     << new StaticFunction( "$scale", 0, fcnScale, "Record" )
-    << new StaticFunction( "$uuid", 0, fcnUuid, "Record" )
+    << new StaticFunction( "uuid", 0, fcnUuid, "Record", QString(), false, QStringList(), false, QStringList() << "$uuid" )
     << new StaticFunction( "get_feature", 3, fcnGetFeature, "Record", QString(), false, QStringList(), false, QStringList() << "getFeature" )
 
     //return all attributes string for referencedColumns - this is caught by

diff --git a/src/core/qgsexpressionparser.yy b/src/core/qgsexpressionparser.yy
@@ -196,6 +196,25 @@ expression:
           delete $1;
         }
 
+    | FUNCTION '(' ')'
+        {
+          int fnIndex = QgsExpression::functionIndex(*$1);
+          if (fnIndex == -1)
+          {
+            // this should not actually happen because already in lexer we check whether an identifier is a known function
+            // (if the name is not known the token is parsed as a column)
+            exp_error(parser_ctx, "Function is not known");
+            YYERROR;
+          }
+          if ( QgsExpression::Functions()[fnIndex]->params() != 0 )
+          {
+            exp_error(parser_ctx, "Function is called with wrong number of arguments");
+            YYERROR;
+          }
+          $$ = new QgsExpression::NodeFunction(fnIndex, new QgsExpression::NodeList());
+          delete $1;
+        }
+
     | expression IN '(' exp_list ')'     { $$ = new QgsExpression::NodeInOperator($1, $4, false);  }
     | expression NOT IN '(' exp_list ')' { $$ = new QgsExpression::NodeInOperator($1, $5, true); }
 

diff --git a/src/gui/qgsexpressionbuilderwidget.cpp b/src/gui/qgsexpressionbuilderwidget.cpp
@@ -408,6 +408,8 @@ void QgsExpressionBuilderWidget::updateFunctionTree()
       continue;
     if ( func->params() != 0 )
       name += "(";
+    else if ( !name.startsWith( "$" ) )
+      name += "()";
     registerItem( func->group(), func->name(), " " + name + " ", func->helptext() );
   }
 

diff --git a/tests/src/core/testqgsexpression.cpp b/tests/src/core/testqgsexpression.cpp
@@ -297,6 +297,7 @@ class TestQgsExpression: public QObject
       QTest::newRow( "concat numbers" ) << "1 || 2" << false << QVariant( "12" );
 
       // math functions
+      QTest::newRow( "pi" ) << "pi()" << false << QVariant( M_PI );
       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. );