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U4-2635 Skip past replaced word when checking

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Avoids infinite loop if search and replacement are equal
This commit is contained in:
John
2014-04-29 13:54:26 +02:00
parent 74dd1f9181
commit b4127294e5
2 changed files with 9 additions and 4 deletions
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10
src/Umbraco.Core/StringExtensions.cs
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@@ -1191,11 +1191,13 @@ namespace Umbraco.Core
/// <returns>Updated string</returns>
public static string Replace(this string source, string oldString, string newString, StringComparison stringComparison)
{
// Initialised to zero so it can be used as startIndex on first iteration.
int index = 0;
// This initialisation ensures the first check starts at index zero of the source. On successive checks for
// a match, the source is skipped to immediately after the last replaced occurrence for efficiency
// and to avoid infinite loops when oldString and newString compare equal.
int index = -1 * newString.Length;
// Determine if there are any matches left in source, starting from last found match.
while((index = source.IndexOf(oldString, index, stringComparison)) >= 0)
// Determine if there are any matches left in source, starting from just after the result of replacing the last match.
while((index = source.IndexOf(oldString, index + newString.Length, stringComparison)) >= 0)
{
// Remove the old text.
source = source.Remove(index, oldString.Length);

3
src/Umbraco.Tests/CoreStrings/StringExtensionsTests.cs
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@@ -83,6 +83,9 @@ namespace Umbraco.Tests.CoreStrings
[TestCase("Hello this is my string", "hello", "replaced", "replaced this is my string", StringComparison.CurrentCultureIgnoreCase)]
[TestCase("Hello this is hello my string", "hello", "replaced", "replaced this is replaced my string", StringComparison.CurrentCultureIgnoreCase)]
[TestCase("Hello this is my string", "nonexistent", "replaced", "Hello this is my string", StringComparison.CurrentCultureIgnoreCase)]
[TestCase("Hellohello this is my string", "hello", "replaced", "replacedreplaced this is my string", StringComparison.CurrentCultureIgnoreCase)]
// Ensure replacing with the same string doesn't cause infinite loop.
[TestCase("Hello this is my string", "hello", "hello", "hello this is my string", StringComparison.CurrentCultureIgnoreCase)]
public void ReplaceWithStringComparison(string input, string oldString, string newString, string shouldBe, StringComparison stringComparison)
{
var replaced = input.Replace(oldString, newString, stringComparison);