tdf#59820 - Search for the longest substring in a multiline string

In order to determine the optimal column width of imported ASCII files
in the simple text mode, search for the longest substring in a multiline
string which is determined by a line break.

Change-Id: I2c606dd97549455009b9f8fad2b8ec4386b7b7db
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/120772
Tested-by: Jenkins
Reviewed-by: Eike Rathke <erack@redhat.com>

1 files changed, 53 insertions, 4 deletions

diff --git a/sc/source/core/data/column2.cxx b/sc/source/core/data/column2.cxx
index e3f8284d5061..93e16239dfca 100644
--- a/sc/source/core/data/column2.cxx
+++ b/sc/source/core/data/column2.cxx
@@ -614,6 +614,45 @@ class MaxStrLenFinder
     OUString maMaxLenStr;
     sal_Int32 mnMaxLen;
 
+    // tdf#59820 - search for the longest substring in a multiline string
+    void checkLineBreak(const OUString& aStrVal)
+    {
+        sal_Int32 nFromIndex = 0;
+        sal_Int32 nToIndex = aStrVal.indexOf('\n', nFromIndex);
+        // if there is no line break, just take the length of the entire string
+        if (nToIndex == -1)
+        {
+            mnMaxLen = aStrVal.getLength();
+            maMaxLenStr = aStrVal;
+        }
+        else
+        {
+            sal_Int32 nMaxLen = 0;
+            // search for the longest substring in the multiline string
+            while (nToIndex != -1)
+            {
+                if (nMaxLen < nToIndex - nFromIndex)
+                {
+                    nMaxLen = nToIndex - nFromIndex;
+                }
+                nFromIndex = nToIndex + 1;
+                nToIndex = aStrVal.indexOf('\n', nFromIndex);
+            }
+            // take into consideration the last part of multiline string
+            nToIndex = aStrVal.getLength() - nFromIndex;
+            if (nMaxLen < nToIndex)
+            {
+                nMaxLen = nToIndex;
+            }
+            // assign new maximum including its substring
+            if (mnMaxLen < nMaxLen)
+            {
+                mnMaxLen = nMaxLen;
+                maMaxLenStr = aStrVal.subView(nFromIndex);
+            }
+        }
+    }
+
     void checkLength(const ScRefCellValue& rCell)
     {
         const Color* pColor;
@@ -623,8 +662,19 @@ class MaxStrLenFinder
 
         if (aValStr.getLength() > mnMaxLen)
         {
-            mnMaxLen = aValStr.getLength();
-            maMaxLenStr = aValStr;
+            switch (rCell.meType)
+            {
+                case CELLTYPE_NONE:
+                case CELLTYPE_VALUE:
+                    mnMaxLen = aValStr.getLength();
+                    maMaxLenStr = aValStr;
+                    break;
+                case CELLTYPE_EDIT:
+                case CELLTYPE_STRING:
+                case CELLTYPE_FORMULA:
+                default:
+                    checkLineBreak(aValStr);
+            }
         }
     }
 
@@ -642,8 +692,7 @@ public:
     {
         if (rSS.getLength() > mnMaxLen)
         {
-            mnMaxLen = rSS.getLength();
-            maMaxLenStr = rSS.getString();
+            checkLineBreak(rSS.getString());
         }
     }