Read functions from QgsExpression. Updated FunctionDef to store group name and help text. Add comments to code

NOTE: Reading functions list not working yet.

Author: NathanW2

src/core/qgsexpression.cpp

@@ -346,36 +346,36 @@ typedef QgsExpression::FunctionDef FnDef;
 FnDef QgsExpression::BuiltinFunctions[] =
 {
   // math
-  FnDef( "sqrt", 1, fcnSqrt ),
-  FnDef( "sin", 1, fcnSin ),
-  FnDef( "cos", 1, fcnCos ),
-  FnDef( "tan", 1, fcnTan ),
-  FnDef( "asin", 1, fcnAsin ),
-  FnDef( "acos", 1, fcnAcos ),
-  FnDef( "atan", 1, fcnAtan ),
-  FnDef( "atan2", 2, fcnAtan2 ),
+  FnDef( "sqrt", 1, fcnSqrt, "Math"),
+  FnDef( "sin", 1, fcnSin, "Math" ),
+  FnDef( "cos", 1, fcnCos, "Math"),
+  FnDef( "tan", 1, fcnTan, "Math" ),
+  FnDef( "asin", 1, fcnAsin, "Math" ),
+  FnDef( "acos", 1, fcnAcos, "Math" ),
+  FnDef( "atan", 1, fcnAtan, "Math" ),
+  FnDef( "atan2", 2, fcnAtan2, "Math" ),
   // casts
-  FnDef( "toint", 1, fcnToInt ),
-  FnDef( "toreal", 1, fcnToReal ),
-  FnDef( "tostring", 1, fcnToString ),
+  FnDef( "toint", 1, fcnToInt, "Conversions" ),
+  FnDef( "toreal", 1, fcnToReal, "Conversions" ),
+  FnDef( "tostring", 1, fcnToString, "Conversions" ),
   // string manipulation
-  FnDef( "lower", 1, fcnLower ),
-  FnDef( "upper", 1, fcnUpper ),
-  FnDef( "length", 1, fcnLength ),
-  FnDef( "replace", 3, fcnReplace ),
-  FnDef( "regexp_replace", 3, fcnRegexpReplace ),
-  FnDef( "substr", 3, fcnSubstr ),
+  FnDef( "lower", 1, fcnLower, "String" ),
+  FnDef( "upper", 1, fcnUpper, "String" ),
+  FnDef( "length", 1, fcnLength, "String" ),
+  FnDef( "replace", 3, fcnReplace, "String" ),
+  FnDef( "regexp_replace", 3, fcnRegexpReplace, "String" ),
+  FnDef( "substr", 3, fcnSubstr, "String" ),
   // geometry accessors
-  FnDef( "xat", 1, fcnXat, true ),
-  FnDef( "yat", 1, fcnYat, true ),
+  FnDef( "xat", 1, fcnXat, "Geometry", "", true ),
+  FnDef( "yat", 1, fcnYat, "Geometry", "", true ),
+  FnDef( "$area", 0, fcnGeomArea, "Geometry", "", true ),
+  FnDef( "$length", 0, fcnGeomLength, "Geometry", "", true ),
+  FnDef( "$perimeter", 0, fcnGeomPerimeter, "Geometry", "", true ),
+  FnDef( "$x", 0, fcnX, "Geometry", "", true ),
+  FnDef( "$y", 0, fcnY, "Geometry", "" , true ),
   // special columns
-  FnDef( "$rownum", 0, fcnRowNumber ),
-  FnDef( "$area", 0, fcnGeomArea, true ),
-  FnDef( "$length", 0, fcnGeomLength, true ),
-  FnDef( "$perimeter", 0, fcnGeomPerimeter, true ),
-  FnDef( "$x", 0, fcnX, true ),
-  FnDef( "$y", 0, fcnY, true ),
-  FnDef( "$id", 0, fcnFeatureId ),
+  FnDef( "$rownum", 0, fcnRowNumber, "Record" ),
+  FnDef( "$id", 0, fcnFeatureId, "Record")
 };
 
 
@@ -386,7 +386,7 @@ bool QgsExpression::isFunctionName( QString name )
 
 int QgsExpression::functionIndex( QString name )
 {
-  int count = sizeof( BuiltinFunctions ) / sizeof( FunctionDef );
+  int count = sizeof( BuiltinFunctions ) / sizeof( FunctionDef);
   for ( int i = 0; i < count; i++ )
   {
     if ( QString::compare( name, BuiltinFunctions[i].mName, Qt::CaseInsensitive ) == 0 )

src/core/qgsexpression.h

@@ -30,7 +30,7 @@ The expressions try to follow both syntax and semantics of SQL expressions.
 
 Usage:
 
-  QgsExpression exp("gid*2 > 10 and type not in ('D','F');
+  QgsExpression exp("gid*2 > 10 and type not in ('D','F'));
   if (exp.hasParserError())
   {
     // show error message with parserErrorString() and exit
@@ -170,12 +170,20 @@ class CORE_EXPORT QgsExpression
 
     struct FunctionDef
     {
-      FunctionDef( QString fnname, int params, FcnEval fcn, bool usesGeometry = false )
-          : mName( fnname ), mParams( params ), mFcn( fcn ), mUsesGeometry( usesGeometry ) {}
+      FunctionDef( QString fnname, int params, FcnEval fcn, QString group, QString helpText = "", bool usesGeometry = false )
+          : mName( fnname ), mParams( params ), mFcn( fcn ), mUsesGeometry( usesGeometry ), mGroup( group ), mHelpText( helpText ) {}
+      /** The name of the function. */
       QString mName;
+      /** The number of parameters this function takes. */
       int mParams;
+      /** Pointer to fucntion. */
       FcnEval mFcn;
+      /** Does this function use a geometry object. */
       bool mUsesGeometry;
+      /** The group the function belongs to. */
+      QString mGroup;
+      /** The help text for the function. */
+      QString mHelpText;
     };
 
     static FunctionDef BuiltinFunctions[];

src/gui/qgsexpressionbuilder.cpp

@@ -15,6 +15,7 @@
 
 #include "qgsexpressionbuilder.h"
 #include "qgslogger.h"
+#include "qgsexpression.h"
 
 QgsExpressionBuilderWidget::QgsExpressionBuilderWidget(QgsVectorLayer *layer)
     : QWidget(),
@@ -40,34 +41,15 @@ QgsExpressionBuilderWidget::QgsExpressionBuilderWidget(QgsVectorLayer *layer)
                                                 "<br> Joins two values together into a string " \
                                                 "<br> <i>Usage:</i><br>'Dia' || Diameter");
 
-    this->registerItem("Geometry","Area"," $area ","<b>$area</b> <br> Returns the area the object." \
-                                                                "<br> Only applies to polygons.");
-    this->registerItem("Geometry","Length"," $length ","<b>$length</b> <br> Returns the length the object. <br> Only applies to polylines.");
-    this->registerItem("Geometry","Perimeter"," $perimeter ");
-    this->registerItem("Geometry","X"," $x ");
-    this->registerItem("Geometry","Y"," $y ");
-    this->registerItem("Geometry","XAt"," xat( ");
-    this->registerItem("Geometry","YAt"," yat(  ");
-
-    this->registerItem("String","Lower Case"," lower( ");
-    this->registerItem("String","Upper Case"," upper( ");
-    this->registerItem("String","Length"," length( ");
-    this->registerItem("String","Replace"," replace(,,, ");
-    this->registerItem("String","Regex Replace"," regexp_replace(,,, ");
-    this->registerItem("String","Substring"," substr(,,, ");
-
-    this->registerItem("Math","Square Root"," sqrt( ");
-    this->registerItem("Math","SIN"," sin( ");
-    this->registerItem("Math","COS"," cos( ");
-    this->registerItem("Math","TAN"," tan( ");
-    this->registerItem("Math","ASIN"," asin( ");
-    this->registerItem("Math","ACOS"," acos( ");
-    this->registerItem("Math","ATAN"," atan( ");
-    this->registerItem("Math","ATAN2"," atan2(, ");
-
-    this->registerItem("Casting","To integer"," toint( ");
-    this->registerItem("Casting","To real"," toreal( ");
-    this->registerItem("Casting","To string"," tostring( ");
+    int count = sizeof( QgsExpression::BuiltinFunctions ) / sizeof( QgsExpression::FunctionDef);
+    for ( int i = 0; i < count; i++ )
+    {
+        QgsExpression::FunctionDef func = QgsExpression::BuiltinFunctions[i];
+        QString name = func.mName;
+        if ( func.mParams >= 1 )
+            name + "(";
+        this->registerItem(func.mGroup,func.mName, " " + name + " ", func.mHelpText);
+    };
 }
 
 QgsExpressionBuilderWidget::~QgsExpressionBuilderWidget()
@@ -191,3 +173,26 @@ void QgsExpressionBuilderWidget::setExpressionString(const QString expressionStr
     this->txtExpressionString->setPlainText(expressionString);
 }
 
+bool QgsExpressionBuilderWidget::hasExpressionError()
+{
+    QString text = this->txtExpressionString->toPlainText();
+    QgsExpression exp( text );
+    return exp.hasParserError();
+}
+
+void QgsExpressionBuilderWidget::on_txtExpressionString_textChanged()
+{
+    QString text = this->txtExpressionString->toPlainText();
+    QgsExpression exp( text );
+    if ( exp.hasParserError())
+    {
+        this->txtExpressionString->setStyleSheet("background-color: rgba(255, 6, 10, 75);");
+    }
+    else
+    {
+        this->txtExpressionString->setStyleSheet("");
+    }
+}
+
+
+

src/gui/qgsexpressionbuilder.h

@@ -33,15 +33,20 @@ class QgsExpressionItem : public QStandardItem
             ExpressionNode
         };
 
-        QgsExpressionItem(QString label, QString expressionText, QString helpText, QgsExpressionItem::ItemType itemType = ExpressionNode)
+        QgsExpressionItem(QString label,
+                          QString expressionText,
+                          QString helpText,
+                          QgsExpressionItem::ItemType itemType = ExpressionNode)
             : QStandardItem(label)
         {
             mExpressionText = expressionText;
             mHelpText = helpText;
             mType = itemType;
         }
 
-        QgsExpressionItem(QString label, QString expressionText, QgsExpressionItem::ItemType itemType = ExpressionNode)
+        QgsExpressionItem(QString label,
+                          QString expressionText,
+                          QgsExpressionItem::ItemType itemType = ExpressionNode)
             : QStandardItem(label)
         {
             mExpressionText = expressionText;
@@ -51,7 +56,10 @@ class QgsExpressionItem : public QStandardItem
         QString getExpressionText() {   return mExpressionText;  }
 
         QString getHelpText() {  return mHelpText;  }
-
+        /** Set the help text for the current item
+          *
+          * @note The help text can be set as a html string.
+          */
         void setHelpText(QString helpText) { mHelpText = helpText; }
 
         QgsExpressionItem::ItemType getItemType() { return mType ; }
@@ -68,19 +76,41 @@ class QgsExpressionBuilderWidget : public QWidget, private Ui::QgsExpressionBuil
     QgsExpressionBuilderWidget(QgsVectorLayer * layer);
     ~QgsExpressionBuilderWidget();
 
+    /** Loads all the field names from the layer.
+      * @remarks Should this really be public couldn't we just do this for the user?
+      */
     void loadFieldNames();
-    void fillFieldValues(int fieldIndex, int countLimit);
+
+    /** Gets the expression string that has been set in the expression area.
+      * @returns The expression as a string. */
     QString getExpressionString();
+
+    /** Sets the expression string for the widget */
     void setExpressionString(const QString expressionString);
+
+    /** Registers a node item for the expression builder.
+      * @param group The group the item will be show in the tree view.  If the group doesn't exsit it will be created.
+      * @param label The label that is show to the user for the item in the tree.
+      * @param expressionText The text that is inserted into the expression area when the user double clicks on the item.
+      * @param helpText The help text that the user will see when item is selected.
+      * @param type The type of the expression item.
+      */
     void registerItem(QString group, QString label,QString expressionText,
-                      QString helpText = "",QgsExpressionItem::ItemType type = QgsExpressionItem::ExpressionNode);
+                      QString helpText = "",
+                      QgsExpressionItem::ItemType type = QgsExpressionItem::ExpressionNode);
+
+    /** Does the expression used in the widget have any errors */
+    bool hasExpressionError();
 
 public slots:
     void on_mAllPushButton_clicked();
     void on_expressionTree_clicked(const QModelIndex &index);
     void on_expressionTree_doubleClicked(const QModelIndex &index);
+    void on_txtExpressionString_textChanged();
 
 private:
+    void fillFieldValues(int fieldIndex, int countLimit);
+
     QgsVectorLayer *mLayer;
     QStandardItemModel *mModel;
     QMap<QString, QgsExpressionItem*> mExpressionGroups;