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Fix redundant iteration while splitting lines #14851

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Merged
rjmholt merged 4 commits into from
Apr 12, 2021
Merged

Fix redundant iteration while splitting lines #14851

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c102315
Fix GenerateLinesWithoutWordWrap()
iSazonov Jan 25, 2021
0bc0827
Work with review feedback
hez2010 Feb 19, 2021
892491c
Apply changes based on review feedback
hez2010 Mar 3, 2021
d1f3d7a
Fix Length(string, int) override implementation
hez2010 Mar 15, 2021
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16 changes: 9 additions & 7 deletions src/System.Management.Automation/FormatAndOutput/common/ComplexWriter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -416,10 +416,12 @@ private static StringCollection GenerateLinesWithoutWordWrap(DisplayCells displa

for (int k = 0; k < lines.Length; k++)
{
if (lines[k] == null || displayCells.Length(lines[k]) <= firstLineLen)
string currentLine = lines[k];

if (currentLine == null || displayCells.Length(currentLine) <= firstLineLen)
{
// we do not need to split further, just add
retVal.Add(lines[k]);
retVal.Add(currentLine);
continue;
}

Expand All @@ -432,15 +434,15 @@ private static StringCollection GenerateLinesWithoutWordWrap(DisplayCells displa

int offset = 0; // offset into the line we are splitting

while (true)
while (offset < currentLine.Length)
{
// acquire the current active display line length (it can very from call to call)
int currentDisplayLen = accumulator.ActiveLen;

// determine if the current tail would fit or not

// for the remaining part of the string, determine its display cell count
int currentCellsToFit = displayCells.Length(lines[k], offset);
int currentCellsToFit = displayCells.Length(currentLine, offset);

// determine if we fit into the line
int excessCells = currentCellsToFit - currentDisplayLen;
Expand All @@ -449,7 +451,7 @@ private static StringCollection GenerateLinesWithoutWordWrap(DisplayCells displa
{
// we are not at the end of the string, select a sub string
// that would fit in the remaining display length
int charactersToAdd = displayCells.GetHeadSplitLength(lines[k], offset, currentDisplayLen);
int charactersToAdd = displayCells.GetHeadSplitLength(currentLine, offset, currentDisplayLen);

if (charactersToAdd <= 0)
{
Expand All @@ -463,7 +465,7 @@ private static StringCollection GenerateLinesWithoutWordWrap(DisplayCells displa
else
{
// of the given length, add it to the accumulator
accumulator.AddLine(lines[k].Substring(offset, charactersToAdd));
accumulator.AddLine(currentLine.Substring(offset, charactersToAdd));
}

// increase the offset by the # of characters added
Expand All @@ -472,7 +474,7 @@ private static StringCollection GenerateLinesWithoutWordWrap(DisplayCells displa
else
{
// we reached the last (partial) line, we add it all
accumulator.AddLine(lines[k].Substring(offset));
accumulator.AddLine(currentLine.Substring(offset));
break;
}
}
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13 changes: 10 additions & 3 deletions src/System.Management.Automation/FormatAndOutput/out-console/ConsoleLineOutput.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -87,8 +87,15 @@ internal DisplayCellsPSHost(PSHostRawUserInterface rawUserInterface)

internal override int Length(string str, int offset)
{
Dbg.Assert(offset >= 0, "offset >= 0");
Dbg.Assert(string.IsNullOrEmpty(str) || (offset < str.Length), "offset < str.Length");
if (string.IsNullOrEmpty(str))
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@xtqqczze xtqqczze Mar 16, 2021

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@iSazonov Why are changes to this method necessary to fix the issue? In particular do we need replace assert with exception in this internal method?

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@iSazonov iSazonov Mar 17, 2021

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The change is not direct fix for the issue. It is related the issue. It makes the code more reliable.
If we don't change the method we will have different behavior for debug and release code that might confuse.

{
return 0;
}

if (offset < 0 || offset >= str.Length)
{
throw PSTraceSource.NewArgumentException(nameof(offset));
}

try
{
Expand All @@ -100,7 +107,7 @@ internal override int Length(string str, int offset)
// we will fallback to the default value.
}

return string.IsNullOrEmpty(str) ? 0 : str.Length - offset;
return str.Length - offset;
}

internal override int Length(string str)
Expand Down