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Date: Sun, 6 Sep 2009 21:58:57 -0700 (PDT)
From: "Henri Yandell (JIRA)" <jira@apache.org>
To: issues@commons.apache.org
Subject: [jira] Commented: (LANG-502) new method
 StringUtils.replaceIgnoreCase (with patch)
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    [ https://issues.apache.org/jira/browse/LANG-502?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12752010#action_12752010 ] 

Henri Yandell commented on LANG-502:
------------------------------------

Given that we have a fast replace method; one question would be whether to add a private underlying method and a last argument of boolean ignoreCase. Then have it make a couple of string variable copies and if true make the copies lowercase. A very slight performance hit for the current replace (two variable declarations to existing objects and an if statement on a boolean) and not much increase in terms of maintenance.

Other option would be to decide this isn't a common enough need for performance to be critical and using regex with /i is the way to go.

> new method StringUtils.replaceIgnoreCase (with patch)
> -----------------------------------------------------
>
>                 Key: LANG-502
>                 URL: https://issues.apache.org/jira/browse/LANG-502
>             Project: Commons Lang
>          Issue Type: Improvement
>         Environment: all
>            Reporter: Flo
>            Priority: Minor
>             Fix For: 3.0
>
>
> Method implementation:
> 	/**
> 	 * Searches for all appearances of <code>searchString</code> (ignoring case) in <code>text</code> and replaces them by <code>replacement</code>.
> 	 * The difference to {@link String#replace(CharSequence, CharSequence)} and {@link StringUtils#replace(String, String, String)} is that this implementation ignores case.
> 	 *  
> 	 * @param text The text in which to do replacements.
> 	 * @param searchString The string to remove from the text (ignoring case).
> 	 * @param replacement The string to put instead of the searchString.
> 	 * @return A new string with all searchString replaced by replacement.
> 	 * @author frickert
> 	 */
> 	public static String replaceIgnoreCase(String text, String searchString, String replacement)
> 	{
> 		String lowerCaseText = text.toLowerCase();
> 		String lowerCaseSearchString = searchString.toLowerCase();
> 		StringBuilder sb = new StringBuilder(text);
> 		int searchStart = 0;
> 		final int modifierPerReplacement = replacement.length() - searchString.length();
> 		int sbDrift = 0; // by doing replacements in sb, sb and the text drift off in length and index in case the searchString and the replacement are of different length
> 		int finding = lowerCaseText.indexOf(lowerCaseSearchString, searchStart);
> 		while (finding >= 0)
> 		{
> 			sb.replace(finding + sbDrift, finding + sbDrift + searchString.length(), replacement);
> 			sbDrift += modifierPerReplacement;
> 			searchStart = finding + searchString.length();
> 			finding = lowerCaseText.indexOf(lowerCaseSearchString, searchStart);
> 		}
> 		return sb.toString();
> 	}
> test cases:
>     public void testReplaceIgnoreCase() throws Throwable {
>         String is;
>         is = CommonHelpers.replaceIgnoreCase("bobOBOBobOB", "Bob", "Flo");
>         assertEquals("search really ignores case", "FloOFlooFlo", is);
>         is = CommonHelpers.replaceIgnoreCase("bobOBOBobOB", "Bob", "Flo");
>         assertEquals("replacement does care about case", "FloOFlooFlo", is);
>         is = CommonHelpers.replaceIgnoreCase("bob bob bob", "Bob", "Florian");
>         assertEquals("length difference of searchString and replacement > 0", "Florian Florian Florian", is);
>         is = CommonHelpers.replaceIgnoreCase("bob bob bob", "Bob", "Ed");
>         assertEquals("length difference of searchString and replacement < 0", "Ed Ed Ed", is);
>         is = CommonHelpers.replaceIgnoreCase("GROSS und klein", "und", "&");
>         assertEquals("originals case is preserved in not replace chars", "GROSS & klein", is);
>     }

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