From 355b2427118dbb94aee678019e5ef051bc01b802 Mon Sep 17 00:00:00 2001
From: Andrew John Hughes <gnu_andrew@member.fsf.org>
Date: Sun, 15 Jun 2008 21:33:56 +0000
Subject: 2008-06-15  Andrew John Hughes  <gnu_andrew@member.fsf.org>

	PR classpath/36477:
	* gnu/java/lang/CPStringBuilder.java,
	(setLength(int)): Don't ensure capacity when
	new length is 0.
	(ensureCapacity(int)): Allocate double the minimum
	capacity rather than double the array length when
	allocating a new array after a write.
---
 gnu/java/lang/CPStringBuilder.java | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

(limited to 'gnu/java/lang/CPStringBuilder.java')

diff --git a/gnu/java/lang/CPStringBuilder.java b/gnu/java/lang/CPStringBuilder.java
index 688f36dbc..27e7d2cc7 100644
--- a/gnu/java/lang/CPStringBuilder.java
+++ b/gnu/java/lang/CPStringBuilder.java
@@ -204,8 +204,11 @@ public final class CPStringBuilder
     int valueLength = value.length;
 
     /* Always call ensureCapacity in order to preserve
-       copy-on-write semantics.  */
-    ensureCapacity(newLength);
+       copy-on-write semantics, except when the position
+       is simply being reset
+    */
+    if (newLength > 0)
+      ensureCapacity(newLength);
 
     if (newLength < valueLength)
       {
@@ -1036,18 +1039,24 @@ public final class CPStringBuilder
    * Increase the capacity of this <code>StringBuilder</code>. This will
    * ensure that an expensive growing operation will not occur until either
    * <code>minimumCapacity</code> is reached or the array has been allocated.
-   * The buffer is grown to the larger of <code>minimumCapacity</code> and
+   * The buffer is grown to either <code>minimumCapacity * 2</code>, if
+   * the array has been allocated or the larger of <code>minimumCapacity</code> and 
    * <code>capacity() * 2 + 2</code>, if it is not already large enough.
    *
    * @param minimumCapacity the new capacity
-   * @see #capacity()
+   * @see #length()
    */
   public void ensureCapacity(int minimumCapacity)
   {
     if (allocated || minimumCapacity > value.length)
       {
-        int max = value.length * 2 + 2;
-        minimumCapacity = (minimumCapacity < max ? max : minimumCapacity);
+	if (minimumCapacity > value.length)
+	  {
+	    int max = value.length * 2 + 2;
+	    minimumCapacity = (minimumCapacity < max ? max : minimumCapacity);
+	  }
+	else
+	  minimumCapacity *= 2;
 	allocateArray(minimumCapacity);
       }
   }
-- 
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