Support string concatenation using the standard sql concatenation operator ||

Developed for Faunalia (http://www.faunalia.it) with funding from Regione Toscana - Sistema Informativo per la Gestione del Territorio e dell' Ambiente [RT-SIGTA].
For the project: "Sviluppo di prodotti software GIS open-source basati sui prodotti QuantumGIS e Postgis (CIG 037728516E)"



git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@13940 c8812cc2-4d05-0410-92ff-de0c093fc19c

Author: wonder

python/core/qgssearchtreenode.sip

@@ -36,9 +36,13 @@ class QgsSearchTreeNode
       opASIN,
       opACOS,
       opATAN,
+
+      // conversion
       opTOINT,
       opTOREAL,
       opTOSTRING,
+
+      // measuring
       opLENGTH,
       opAREA,
 
@@ -50,7 +54,10 @@ class QgsSearchTreeNode
       opGE,   // >=
       opLE,   // <=
       opRegexp, // ~
-      opLike  // LIKE
+      opLike,  // LIKE
+
+      // string handling
+      opCONCAT
     };
 
     //! constructors

src/core/qgssearchstringlexer.ll

@@ -92,6 +92,8 @@ string      "'"{str_char}*"'"
 "to real" { yylval.op = QgsSearchTreeNode::opTOREAL; return FUNCTION;}
 "to string" { yylval.op = QgsSearchTreeNode::opTOSTRING; return FUNCTION;}
 
+"||"   { return CONCAT; }
+
 [+-/*^]    { return yytext[0]; }
 
 [()]      { return yytext[0]; }

src/core/qgssearchstringparser.yy

@@ -62,6 +62,7 @@ void addToTmpNodes(QgsSearchTreeNode* node);
 %token <number> NUMBER
 %token <op> COMPARISON
 %token <op> FUNCTION
+%token CONCAT
 %token IS
 %token AREA
 %token LENGTH
@@ -95,6 +96,8 @@ void addToTmpNodes(QgsSearchTreeNode* node);
 
 %left COMPARISON
 
+%left CONCAT
+
 %left '+' '-'
 %left '*' '/'
 %left '^'
@@ -136,6 +139,7 @@ scalar_exp:
     | '(' scalar_exp ')'          { $$ = $2; }
     | '+' scalar_exp %prec UMINUS { $$ = $2; }
     | '-' scalar_exp %prec UMINUS { $$ = $2; if ($$->type() == QgsSearchTreeNode::tNumber) $$->setNumber(- $$->number()); }
+    | scalar_exp CONCAT scalar_exp { $$ = new QgsSearchTreeNode(QgsSearchTreeNode::opCONCAT, $1, $3); joinTmpNodes($$, $1, $3); }
     | AREA                        { $$ = new QgsSearchTreeNode(QgsSearchTreeNode::opAREA, 0, 0); addToTmpNodes($$); }
     | LENGTH                      { $$ = new QgsSearchTreeNode(QgsSearchTreeNode::opLENGTH, 0, 0); addToTmpNodes($$); }
     | NUMBER                      { $$ = new QgsSearchTreeNode($1); addToTmpNodes($$); }

src/core/qgssearchtreenode.cpp

@@ -214,6 +214,9 @@ QString QgsSearchTreeNode::makeSearchString()
         case opRegexp: str += " ~ "; break;
         case opLike: str += " LIKE "; break;
 
+          // TODO: other opeators / functions
+        case opCONCAT: str += " || "; break;
+
         default: str += " ? ";
       }
 
@@ -548,12 +551,29 @@ QgsSearchTreeValue QgsSearchTreeNode::valueAgainst( const QgsFieldMap& fields, c
       //don't convert to numbers in case of string concatenation
       if ( mLeft && mRight && !value1.isNumeric() && !value2.isNumeric() )
       {
+        // TODO: concatenation using '+' operator should be removed in favor of '||' operator
+        // because it may lead to surprising behavior if numbers are stored in a string
         if ( mOp == opPLUS )
         {
           return QgsSearchTreeValue( value1.string() + value2.string() );
         }
       }
 
+      // string concatenation ||
+      if ( mLeft && mRight && mOp == opCONCAT )
+      {
+        if ( value1.isNumeric() && value2.isNumeric() )
+        {
+          return QgsSearchTreeValue( 5, "Operator doesn't match the argument types." );
+        }
+        else
+        {
+          QString arg1 = value1.isNumeric() ? QString::number( value1.number() ) : value1.string();
+          QString arg2 = value2.isNumeric() ? QString::number( value2.number() ) : value2.string();
+          return QgsSearchTreeValue( arg1 + arg2 );
+        }
+      }
+
       // for other operators, convert strings to numbers if needed
       double val1, val2;
       if ( value1.isNumeric() )

src/core/qgssearchtreenode.h

@@ -72,9 +72,13 @@ class CORE_EXPORT QgsSearchTreeNode
       opASIN,
       opACOS,
       opATAN,
+
+      // conversion
       opTOINT,
       opTOREAL,
       opTOSTRING,
+
+      // measuring
       opLENGTH,
       opAREA,
 
@@ -88,7 +92,10 @@ class CORE_EXPORT QgsSearchTreeNode
       opGE,   // >=
       opLE,   // <=
       opRegexp, // ~
-      opLike  // LIKE
+      opLike,  // LIKE
+
+      // string handling
+      opCONCAT
     };
 
     //! constructors