StringUtils: new #trim method

In [1] we could use a "trim" function to remove leading/trailing '/'
from paths.

[1] https://gerrithub.io/q/I1f2a07327d1a1d8149ee482bc2529b7e1a5303db

Change-Id: I490e6afe5c8e6c164d07442b1b388f8a131b4c50

2 files changed, 57 insertions, 0 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/StringUtilsTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/StringUtilsTest.java
index 015da164c3..9a1c710752 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/StringUtilsTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/StringUtilsTest.java
@@ -12,6 +12,7 @@ package org.eclipse.jgit.util;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertThrows;
 import static org.junit.Assert.assertTrue;
 
@@ -172,4 +173,22 @@ public class StringUtilsTest {
 		assertEquals("foo bar ",
 				StringUtils.commonPrefix("foo bar 42", "foo bar 24"));
 	}
+
+	@Test
+	public void testTrim() {
+		assertEquals("a", StringUtils.trim("a", '/'));
+		assertEquals("aaaa", StringUtils.trim("aaaa", '/'));
+		assertEquals("aaa", StringUtils.trim("/aaa", '/'));
+		assertEquals("aaa", StringUtils.trim("aaa/", '/'));
+		assertEquals("aaa", StringUtils.trim("/aaa/", '/'));
+		assertEquals("aa/aa", StringUtils.trim("/aa/aa/", '/'));
+		assertEquals("aa/aa", StringUtils.trim("aa/aa", '/'));
+
+		assertEquals("", StringUtils.trim("", '/'));
+		assertEquals("", StringUtils.trim("/", '/'));
+		assertEquals("", StringUtils.trim("//", '/'));
+		assertEquals("", StringUtils.trim("///", '/'));
+
+		assertNull(StringUtils.trim(null, '/'));
+	}
 }
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/util/StringUtils.java b/org.eclipse.jgit/src/org/eclipse/jgit/util/StringUtils.java
index 2fbd12dcc5..e381a3bcc9 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/util/StringUtils.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/util/StringUtils.java
@@ -278,6 +278,44 @@ public final class StringUtils {
 	}
 
 	/**
+	 * Remove the specified character from beginning and end of a string
+	 * <p>
+	 * If the character repeats, all copies
+	 *
+	 * @param str input string
+	 * @param c character to remove
+	 * @return the input string with c
+	 * @since 7.2
+	 */
+	public static String trim(String str, char c) {
+		if (str == null || str.length() == 0) {
+			return str;
+		}
+
+		int endPos = str.length()-1;
+		while (endPos >= 0 && str.charAt(endPos) == c) {
+			endPos--;
+		}
+
+		// Whole string is c
+		if (endPos == -1) {
+			return EMPTY;
+		}
+
+		int startPos = 0;
+		while (startPos < endPos && str.charAt(startPos) == c) {
+			startPos++;
+		}
+
+		if (startPos == 0 && endPos == str.length()-1) {
+			// No need to copy
+			return str;
+		}
+
+		return str.substring(startPos, endPos+1);
+	}
+
+	/**
 	 * Appends {@link Constants#DOT_GIT_EXT} unless the given name already ends
 	 * with that suffix.
 	 *