From fbda356a749b3ad4eacd04a74809a1e257928e46 Mon Sep 17 00:00:00 2001
From: Stefanos Natsis <uclaros@gmail.com>
Date: Tue, 27 Apr 2021 07:05:23 +0300
Subject: [PATCH] Order map keys by length before using in replace function

Fix #42940
---
 resources/function_help/json/replace          |  5 +++--
 src/core/expression/qgsexpressionfunction.cpp | 17 ++++++++++++++++-
 tests/src/core/testqgsexpression.cpp          |  1 +
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/resources/function_help/json/replace b/resources/function_help/json/replace
index 2b824fe0974..655ee3f973d 100644
--- a/resources/function_help/json/replace
+++ b/resources/function_help/json/replace
@@ -13,9 +13,10 @@
                     { "expression":"replace('QGIS ABC',array('A','B','C'),array('X','Y','Z'))", "returns":"'QGIS XYZ'"},
                     { "expression":"replace('QGIS',array('Q','S'),'')", "returns":"'GI'"} ] },
   { "variant": "Map variant",
-      "variant_description": "Returns a string with the supplied map keys replaced by paired values.",
+      "variant_description": "Returns a string with the supplied map keys replaced by paired values. Longer map keys are evaluated first.",
       "arguments": [ {"arg":"string","description":"the input string"},
                      {"arg":"map","description":"the map containing keys and values"} ],
-      "examples": [ { "expression":"replace('APP SHOULD ROCK',map('APP','QGIS','SHOULD','DOES'))", "returns":"'QGIS DOES ROCK'"} ]
+      "examples": [ { "expression":"replace('APP SHOULD ROCK',map('APP','QGIS','SHOULD','DOES'))", "returns":"'QGIS DOES ROCK'"},
+                    { "expression":"replace('forty two',map('for','4','two','2','forty two','42'))", "returns":"'42'"} ]
   }]
 }
diff --git a/src/core/expression/qgsexpressionfunction.cpp b/src/core/expression/qgsexpressionfunction.cpp
index c6b580dbc0e..ed7ba5a163b 100644
--- a/src/core/expression/qgsexpressionfunction.cpp
+++ b/src/core/expression/qgsexpressionfunction.cpp
@@ -1367,10 +1367,25 @@ static QVariant fcnReplace( const QVariantList &values, const QgsExpressionConte
   {
     QString str = QgsExpressionUtils::getStringValue( values.at( 0 ), parent );
     QVariantMap map = QgsExpressionUtils::getMapValue( values.at( 1 ), parent );
+    QVector< QPair< QString, QString > > mapItems;
 
     for ( QVariantMap::const_iterator it = map.constBegin(); it != map.constEnd(); ++it )
     {
-      str = str.replace( it.key(), it.value().toString() );
+      mapItems.append( qMakePair( it.key(), it.value().toString() ) );
+    }
+
+    // larger keys should be replaced first since they may contain whole smaller keys
+    std::sort( mapItems.begin(),
+               mapItems.end(),
+               []( const QPair< QString, QString > &pair1,
+                   const QPair< QString, QString > &pair2 )
+    {
+      return ( pair1.first.length() > pair2.first.length() );
+    } );
+
+    for ( auto it = mapItems.constBegin(); it != mapItems.constEnd(); ++it )
+    {
+      str = str.replace( it->first, it->second );
     }
 
     return QVariant( str );
diff --git a/tests/src/core/testqgsexpression.cpp b/tests/src/core/testqgsexpression.cpp
index 1020759f138..266c91f2fdd 100644
--- a/tests/src/core/testqgsexpression.cpp
+++ b/tests/src/core/testqgsexpression.cpp
@@ -1312,6 +1312,7 @@ class TestQgsExpression: public QObject
       QTest::newRow( "replace (unbalanced array, before > after)" ) << "replace('12345', array('1','2','3'), array('6','7'))" << true << QVariant();
       QTest::newRow( "replace (unbalanced array, before < after)" ) << "replace('12345', array('1','2'), array('6','7','8'))" << true << QVariant();
       QTest::newRow( "replace (map)" ) << "replace('APP SHOULD ROCK',map('APP','QGIS','SHOULD','DOES'))" << false << QVariant( "QGIS DOES ROCK" );
+      QTest::newRow( "replace (map with overlapping keys)" ) << "replace('11111',map('1','small','11','large'))" << false << QVariant( "largelargesmall" );
       QTest::newRow( "regexp_replace" ) << "regexp_replace('HeLLo','[eL]+', '-')" << false << QVariant( "H-o" );
       QTest::newRow( "regexp_replace greedy" ) << "regexp_replace('HeLLo','(?<=H).*L', '-')" << false << QVariant( "H-o" );
       QTest::newRow( "regexp_replace non greedy" ) << "regexp_replace('HeLLo','(?<=H).*?L', '-')" << false << QVariant( "H-Lo" );