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add count_substring expression

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Tudor Barascu 2025-09-18 02:08:40 +03:00 committed by GitHub
parent 762c57032b
commit 0936526ba7
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3 changed files with 104 additions and 0 deletions
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57
resources/function_help/json/substr_count Normal file
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@ -0,0 +1,57 @@
{
"name": "substr_count",
"type": "function",
"groups": [
"String"
],
"description": "Counts the number of occurrences of a substring within a string. By default, the function counts non-overlapping occurrences (like in Python). If the third argument is set to true, the function counts overlapping occurrences (like in QT).",
"arguments": [
{
"arg": "input",
"description": "The input string to search in."
},
{
"arg": "substring",
"description": "The substring to search for."
},
{
"arg": "overlapping",
"description": "Optional flag to control whether overlapping occurrences should be counted. Defaults to false (non-overlapping counting). Set to true to count overlapping occurrences."
}
],
"examples": [
{
"expression": "substr_count('banana', 'an')",
"returns": "2",
"description": "Counts non-overlapping occurrences of 'an' in 'banana'."
},
{
"expression": "substr_count('Funniness', 'n')",
"returns": "3",
"description": "Counts non-overlapping occurrences of 'n' in 'Funniness'."
},
{
"expression": "substr_count('aaaaa', 'aa')",
"returns": "2",
"description": "Counts non-overlapping occurrences of 'aa' in 'aaaaa'."
},
{
"expression": "substr_count('aaaaa', 'aa', true)",
"returns": "4",
"description": "Counts overlapping occurrences of 'aa' in 'aaaaa'. The substring 'aa' appears four times in an overlapping fashion."
},
{
"expression": "substr_count('BANANA', 'an')",
"returns": "0",
"description": "Counts non-overlapping occurrences of 'an' in 'BANANA'. Case-sensitive, so no match."
}
],
"tags": [
"text",
"find",
"string",
"substring",
"count",
"occurrence"
]
}

41
src/core/expression/qgsexpressionfunction.cpp
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@ -2698,6 +2698,41 @@ static QVariant fcnRight( const QVariantList &values, const QgsExpressionContext
return string.right( pos );
}
static QVariant fcnSubstrCount( const QVariantList &values, const QgsExpressionContext *, QgsExpression *parent, const QgsExpressionNodeFunction * )
{
if ( values.length() < 2 || values.length() > 3 )
return QVariant();
const QString input = QgsExpressionUtils::getStringValue( values.at( 0 ), parent );
const QString substring = QgsExpressionUtils::getStringValue( values.at( 1 ), parent );
bool overlapping = false;
if ( values.length() == 3 )
{
overlapping = values.at( 2 ).toBool();
}
if ( substring.isEmpty() )
return QVariant( 0 );
int count = 0;
if ( overlapping )
{
count = input.count( substring );
}
else
{
int pos = 0;
while ( ( pos = input.indexOf( substring, pos ) ) != -1 )
{
count++;
pos += substring.length();
}
}
return QVariant( count );
}
static QVariant fcnLeft( const QVariantList &values, const QgsExpressionContext *, QgsExpression *parent, const QgsExpressionNodeFunction * )
{
QString string = QgsExpressionUtils::getStringValue( values.at( 0 ), parent );
@ -8714,6 +8749,12 @@ const QList<QgsExpressionFunction *> &QgsExpression::Functions()
<< new QgsStaticExpressionFunction( QStringLiteral( "set_timezone" ), { QgsExpressionFunction::Parameter( QStringLiteral( "datetime" ) ), QgsExpressionFunction::Parameter( QStringLiteral( "timezone" ) ) }, fcnSetTimeZone, QStringLiteral( "Date and Time" ) )
<< new QgsStaticExpressionFunction( QStringLiteral( "convert_timezone" ), { QgsExpressionFunction::Parameter( QStringLiteral( "datetime" ) ), QgsExpressionFunction::Parameter( QStringLiteral( "timezone" ) ) }, fcnConvertTimeZone, QStringLiteral( "Date and Time" ) )
<< new QgsStaticExpressionFunction( QStringLiteral( "lower" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "string" ) ), fcnLower, QStringLiteral( "String" ) )
<< new QgsStaticExpressionFunction( QStringLiteral( "substr_count" ), QgsExpressionFunction::ParameterList()
<< QgsExpressionFunction::Parameter( QStringLiteral( "input" ) )
<< QgsExpressionFunction::Parameter( QStringLiteral( "substring" ) )
<< QgsExpressionFunction::Parameter( QStringLiteral( "overlapping" ), true, false ), // Optional parameter with default value of false
fcnSubstrCount,
QStringLiteral( "String" ) )
<< new QgsStaticExpressionFunction( QStringLiteral( "upper" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "string" ) ), fcnUpper, QStringLiteral( "String" ) )
<< new QgsStaticExpressionFunction( QStringLiteral( "title" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "string" ) ), fcnTitle, QStringLiteral( "String" ) )
<< new QgsStaticExpressionFunction( QStringLiteral( "trim" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "string" ) ), fcnTrim, QStringLiteral( "String" ) )

6
tests/src/core/testqgsexpression.cpp
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@ -1841,6 +1841,12 @@ class TestQgsExpression : public QObject
QTest::newRow( "regexp_replace non greedy" ) << "regexp_replace('HeLLo','(?<=H).*?L', '-')" << false << QVariant( "H-Lo" );
QTest::newRow( "regexp_replace cap group" ) << "regexp_replace('HeLLo','(eL)', 'x\\\\1x')" << false << QVariant( "HxeLxLo" );
QTest::newRow( "regexp_replace invalid" ) << "regexp_replace('HeLLo','[[[', '-')" << true << QVariant();
QTest::newRow( "substr_count basic" ) << "substr_count('banana', 'an')" << false << QVariant( 2 );
QTest::newRow( "substr_count basic funny" ) << "substr_count('Funniness', 'n')" << false << QVariant( 3 );
QTest::newRow( "substr_count non-overlapping counted" ) << "substr_count('aaaaa', 'aa')" << false << QVariant( 2 );
QTest::newRow( "substr_count overlapping counted" ) << "substr_count('aaaaa', 'aa', true)" << false << QVariant( 4 );
QTest::newRow( "substr_count empty needle" ) << "substr_count('abc', '')" << false << QVariant( 0 );
QTest::newRow( "substr_count case sensitivity" ) << "substr_count('BANANA', 'an')" << false << QVariant( 0 );
QTest::newRow( "reverse string" ) << "reverse('HeLLo')" << false << QVariant( "oLLeH" );
QTest::newRow( "reverse empty string" ) << "reverse('')" << false << QVariant( "" );
QTest::newRow( "substr" ) << "substr('HeLLo', 3,2)" << false << QVariant( "LL" );