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andreasneumannandreasneumann
committedAug 6, 2017
[FEATURE] array_slice expression function
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ltr-3_40final-3_0_0
1 parent 5bd2e88 commit 8978469

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‎resources/function_help/json/array_slice

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@@ -0,0 +1,51 @@
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{
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"name": "array_get",
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"type": "function",
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"description": "Returns a portion of the array. The slice is defined by the startPos and endPos arguments. A slice that ",
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"arguments": [{
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"arg": "array",
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"description": "an array"
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},
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{
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"arg": "startPos",
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"description": "the index of the start position of the slice (0 based). The startPos index is included in the slice. If you use a negative startPos, the index is counted from the end of the list (-1 based)."
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},
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{
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"arg": "endPos",
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"description": "the index of the start position of the slice (0 based). The endPos index is included in the slice. If you use a negative endPos, the index is counted from the end of the list (-1 based)."
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}
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],
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"examples": [{
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"expression": "array_slice(array(1,2,3,4,5),0,3)",
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"returns": "array: 1,2,3,4"
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},
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{
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"expression": "array_slice(array(1,2,3,4,5),0,-1)",
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"returns": "array: 1,2,3,4,5"
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},
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{
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"expression": "array_slice(array(1,2,3,4,5),-5,-1)",
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"returns": "array: 1,2,3,4,5"
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},
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{
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"expression": "array_slice(array(1,2,3,4,5),0,0)",
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"returns": "array: 1"
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},
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{
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"expression": "array_slice(array(1,2,3,4,5),-2,-1)",
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"returns": "array: 4,5"
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},
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{
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"expression": "array_slice(array(1,2,3,4,5),-1,-1)",
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"returns": "array: 5"
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},
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{
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"expression": "array_slice(array('Dufour','Valmiera','Chugiak','Brighton'),1,2)",
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"returns": "array: 'Valmiera','Chugiak'"
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},
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{
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"expression": "array_slice(array_slice(array('Dufour','Valmiera','Chugiak','Brighton'),-2,-1)",
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"returns": "array: 'Chugiak','Brighton'"
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}
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]
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}

‎src/core/expression/qgsexpressionfunction.cpp

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@@ -3602,6 +3602,30 @@ static QVariant fcnArrayCat( const QVariantList &values, const QgsExpressionCont
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return convertToSameType( list, values.at( 0 ).type() );
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}
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static QVariant fcnArraySlice( const QVariantList &values, const QgsExpressionContext *, QgsExpression *parent )
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{
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QVariantList list = QgsExpressionUtils::getListValue( values.at( 0 ), parent );
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qlonglong startPos = QgsExpressionUtils::getIntValue( values.at( 1 ), parent );
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const qlonglong endPos = QgsExpressionUtils::getIntValue( values.at( 2 ), parent );
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qlonglong sliceLength = 0;
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// negative positions means positions taken relative to the end of the array
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if( startPos < 0 ) {
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startPos = list.length() + startPos;
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}
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if( endPos >= 0 ) {
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sliceLength = endPos - startPos + 1;
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}
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else {
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sliceLength = list.length() + endPos - startPos + 1;
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}
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//avoid negative lengths in QList.mid function
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if (sliceLength < 0) {
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sliceLength = 0;
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}
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list = list.mid(startPos,sliceLength);
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return list;
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}
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static QVariant fcnArrayReverse( const QVariantList &values, const QgsExpressionContext *, QgsExpression *parent )
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{
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QVariantList list = QgsExpressionUtils::getListValue( values.at( 0 ), parent );
@@ -4263,6 +4287,7 @@ const QList<QgsExpressionFunction *> &QgsExpression::Functions()
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<< new QgsStaticExpressionFunction( QStringLiteral( "array_remove_at" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "array" ) ) << QgsExpressionFunction::Parameter( QStringLiteral( "pos" ) ), fcnArrayRemoveAt, QStringLiteral( "Arrays" ) )
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<< new QgsStaticExpressionFunction( QStringLiteral( "array_remove_all" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "array" ) ) << QgsExpressionFunction::Parameter( QStringLiteral( "value" ) ), fcnArrayRemoveAll, QStringLiteral( "Arrays" ) )
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<< new QgsStaticExpressionFunction( QStringLiteral( "array_cat" ), -1, fcnArrayCat, QStringLiteral( "Arrays" ) )
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<< new QgsStaticExpressionFunction( QStringLiteral( "array_slice" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "array" ) ) << QgsExpressionFunction::Parameter( QStringLiteral( "startPos" ) ) << QgsExpressionFunction::Parameter( QStringLiteral( "endPos" ) ), fcnArraySlice, QStringLiteral( "Arrays" ) )
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<< new QgsStaticExpressionFunction( QStringLiteral( "array_reverse" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "array" ) ), fcnArrayReverse, QStringLiteral( "Arrays" ) )
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<< new QgsStaticExpressionFunction( QStringLiteral( "array_intersect" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "array1" ) ) << QgsExpressionFunction::Parameter( QStringLiteral( "array2" ) ), fcnArrayIntersect, QStringLiteral( "Arrays" ) )
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<< new QgsStaticExpressionFunction( QStringLiteral( "array_distinct" ), 1, fcnArrayDistinct, QStringLiteral( "Arrays" ) )

‎tests/src/core/testqgsexpression.cpp

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@@ -2422,6 +2422,9 @@ class TestQgsExpression: public QObject
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QCOMPARE( QgsExpression( "array_intersect(array('1', '2', '3', '4'), array('0', '5'))" ).evaluate( &context ), QVariant( false ) );
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QCOMPARE( QgsExpression( "array_reverse(array('Dufour','Valmiera','Chugiak','Wien','Pisa','Lyon','Essen','Nødebo','Las Palmas')) = array('Las Palmas','Nødebo','Essen','Lyon','Pisa','Wien','Chugiak','Valmiera','Dufour')" ).evaluate( &context ), QVariant( true ) );
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QCOMPARE( QgsExpression( "array_slice(array('Dufour','Valmiera','Chugiak','Brighton'),1,2) = array('Valmiera','Chugiak')" ).evaluate( &context ), QVariant( true ) );
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QCOMPARE( QgsExpression( "array_slice(array('Dufour','Valmiera','Chugiak','Brighton'),-2,-1) = array('Chugiak','Brighton')" ).evaluate( &context ), QVariant( true ) );
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}
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void eval_int_array()
@@ -2486,6 +2489,13 @@ class TestQgsExpression: public QObject
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QCOMPARE( QgsExpression( "array_reverse(array(2,4,0,10)) = array(10,0,4,2)" ).evaluate( &context ), QVariant( true ) );
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QCOMPARE( QgsExpression( "array_slice(array(1,2,3,4,5),0,3) = array(1,2,3,4)" ).evaluate( &context ), QVariant( true ) );
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QCOMPARE( QgsExpression( "array_slice(array(1,2,3,4,5),0,-1) = array(1,2,3,4,5)" ).evaluate( &context ), QVariant( true ) );
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QCOMPARE( QgsExpression( "array_slice(array(1,2,3,4,5),-5,-1) = array(1,2,3,4,5)" ).evaluate( &context ), QVariant( true ) );
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QCOMPARE( QgsExpression( "array_slice(array(1,2,3,4,5),0,0) = array(1)" ).evaluate( &context ), QVariant( true ) );
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QCOMPARE( QgsExpression( "array_slice(array(1,2,3,4,5),-2,-1) = array(4,5)" ).evaluate( &context ), QVariant( true ) );
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QCOMPARE( QgsExpression( "array_slice(array(1,2,3,4,5),-1,-1) = array(5)" ).evaluate( &context ), QVariant( true ) );
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QgsExpression badArray( QStringLiteral( "array_get('not an array', 0)" ) );
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QCOMPARE( badArray.evaluate( &context ), QVariant() );
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QVERIFY( badArray.hasEvalError() );

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