/*
* @(#)StringBuffer.java 1.35 98/04/22
*
* Copyright 1994-1997 by Sun Microsystems, Inc.,
* 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
* All rights reserved.
*
* This software is the confidential and proprietary information
* of Sun Microsystems, Inc. ("Confidential Information"). You
* shall not disclose such Confidential Information and shall use
* it only in accordance with the terms of the license agreement
* you entered into with Sun.
*/
package arlut.csd.Util;
/**
* A hack on java.lang.StringBuffer to allow an instance of
* StringBuffer to be effectively re-used without as much overhead.
* Also provides a public getValue() method to allow
* reusedStringBuffer's to be written out to disk without forcing a
* duplication of the char array.
*
* @author Arthur van Hoff, Jonathan Abbey (jonabbey@arlut.utexas.edu)
* @see java.io.ByteArrayOutputStream
* @see java.lang.String
*/
public final class SharedStringBuffer implements java.io.Serializable {
static final long serialVersionUID = 6662274466893884738L;
private static final int DEFAULTSIZE = 32;
/** The value is used for character storage. */
private char value[];
/** The count is the number of characters in the buffer. */
private int count;
/**
* Constructs a string buffer with no characters in it and an
* initial capacity of 16 characters.
*
*/
public SharedStringBuffer()
{
this(DEFAULTSIZE);
}
/**
* Constructs a string buffer with no characters in it and an
* initial capacity specified by the <code>length</code> argument.
*
* @param length the initial capacity.
* @exception NegativeArraySizeException if the <code>length</code>
* argument is less than <code>0</code>.
*/
public SharedStringBuffer(int length)
{
value = new char[length];
}
/**
* Constructs a string buffer so that it represents the same
* sequence of characters as the string argument. The initial
* capacity of the string buffer is <code>16</code> plus the length
* of the string argument.
*
* @param str the initial contents of the buffer.
*/
public SharedStringBuffer(String str)
{
this(str.length() + 16);
append(str);
}
/**
* Returns the length (character count) of this string buffer.
*
* @return the number of characters in this string buffer.
*/
public synchronized int length()
{
return count;
}
/**
* Returns the current capacity of the String buffer. The capacity
* is the amount of storage available for newly inserted
* characters; beyond which an allocation will occur.
*
* @return the current capacity of this string buffer.
*/
public synchronized int capacity()
{
return value.length;
}
/**
* Copies the buffer value. This is normally only called when shared
* is true. It should only be called from a synchronized method.
*/
private final void copy()
{
char newValue[] = new char[value.length];
System.arraycopy(value, 0, newValue, 0, count);
value = newValue;
}
/**
* Ensures that the capacity of the buffer is at least equal to the
* specified minimum.
* If the current capacity of this string buffer is less than the
* argument, then a new internal buffer is allocated with greater
* capacity. The new capacity is the larger of:
* <ul>
* <li>The <code>minimumCapacity</code> argument.
* <li>Twice the old capacity, plus <code>2</code>.
* </ul>
* If the <code>minimumCapacity</code> argument is nonpositive, this
* method takes no action and simply returns.
*
* @param minimumCapacity the minimum desired capacity.
*/
public synchronized void ensureCapacity(int minimumCapacity)
{
if (minimumCapacity > value.length)
{
expandCapacity(minimumCapacity);
}
}
/**
* This implements the expansion semantics of ensureCapacity but is
* unsynchronized for use internally by methods which are already
* synchronized.
*
* @see arlut.csd.Util.SharedStringBuffer#ensureCapacity(int)
*/
private void expandCapacity(int minimumCapacity)
{
int newCapacity = (value.length + 1) * 2;
if (minimumCapacity > newCapacity)
{
newCapacity = minimumCapacity;
}
char newValue[] = new char[newCapacity];
System.arraycopy(value, 0, newValue, 0, count);
value = newValue;
}
/**
* Sets the length of this String buffer.
* If the <code>newLength</code> argument is less than the current
* length of the string buffer, the string buffer is truncated to
* contain exactly the number of characters given by the
* <code>newLength</code> argument.
* <p>
* If the <code>newLength</code> argument is greater than or equal
* to the current length, sufficient null characters
* (<code>'\u0000'</code>) are appended to the string buffer so that
* length becomes the <code>newLength</code> argument.
* <p>
* The <code>newLength</code> argument must be greater than or equal
* to <code>0</code>.
*
* @param newLength the new length of the buffer.
* @exception StringIndexOutOfBoundsException if the
* <code>newLength</code> argument is invalid.
* @see arlut.csd.Util.SharedStringBuffer#length()
*/
public synchronized void setLength(int newLength)
{
if (newLength < 0)
{
throw new StringIndexOutOfBoundsException(newLength);
}
if (newLength > value.length)
{
expandCapacity(newLength);
}
if (newLength > count)
{
for (; count < newLength; count++)
{
value[count] = '\0';
}
}
else if (newLength == 0)
{
// let's not keep a huge sized buffer around needlessly
if (value.length > 4096)
{
value = new char[DEFAULTSIZE];
}
count = 0;
}
else
{
count = newLength;
}
}
/**
* Returns the character at a specific index in this string buffer.
* <p>
* The first character of a string buffer is at index
* <code>0</code>, the next at index <code>1</code>, and so on, for
* array indexing.
* <p>
* The index argument must be greater than or equal to
* <code>0</code>, and less than the length of this string buffer.
*
* @param index the index of the desired character.
* @return the character at the specified index of this string buffer.
* @exception StringIndexOutOfBoundsException if the index is invalid.
* @see arlut.csd.Util.SharedStringBuffer#length()
*/
public synchronized char charAt(int index)
{
if ((index < 0) || (index >= count))
{
throw new StringIndexOutOfBoundsException(index);
}
return value[index];
}
/**
* Characters are copied from this string buffer into the
* destination character array <code>dst</code>. The first character to
* be copied is at index <code>srcBegin</code>; the last character to
* be copied is at index <code>srcEnd-1.</code> The total number of
* characters to be copied is <code>srcEnd-srcBegin</code>. The
* characters are copied into the subarray of <code>dst</code> starting
* at index <code>dstBegin</code> and ending at index:
* <p><blockquote><pre>
* dstbegin + (srcEnd-srcBegin) - 1
* </pre></blockquote>
*
* @param srcBegin start copying at this offset in the string buffer.
* @param srcEnd stop copying at this offset in the string buffer.
* @param dst the array to copy the data into.
* @param dstBegin offset into <code>dst</code>.
* @exception StringIndexOutOfBoundsException if there is an invalid
* index into the buffer.
*/
public synchronized void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin)
{
if ((srcBegin < 0) || (srcBegin >= count))
{
throw new StringIndexOutOfBoundsException(srcBegin);
}
if ((srcEnd < 0) || (srcEnd > count))
{
throw new StringIndexOutOfBoundsException(srcEnd);
}
if (srcBegin < srcEnd)
{
System.arraycopy(value, srcBegin, dst, dstBegin, srcEnd - srcBegin);
}
}
/**
* The character at the specified index of this string buffer is set
* to <code>ch</code>.
* <p>
* The offset argument must be greater than or equal to
* <code>0</code>, and less than the length of this string buffer.
*
* @param index the index of the character to modify.
* @param ch the new character.
* @exception StringIndexOutOfBoundsException if the index is invalid.
* @see arlut.csd.Util.SharedStringBuffer#length()
*/
public synchronized void setCharAt(int index, char ch)
{
if ((index < 0) || (index >= count))
{
throw new StringIndexOutOfBoundsException(index);
}
value[index] = ch;
}
/**
* Appends the string representation of the <code>Object</code>
* argument to this string buffer.
* <p>
* The argument is converted to a string as if by the method
* <code>String.valueOf</code>, and the characters of that
* string are then appended to this string buffer.
*
* @param obj an <code>Object</code>.
* @return this string buffer.
* @see java.lang.String#valueOf(java.lang.Object)
* @see arlut.csd.Util.SharedStringBuffer#append(java.lang.String)
*/
public synchronized SharedStringBuffer append(Object obj)
{
return append(String.valueOf(obj));
}
/**
* Appends the string to this string buffer.
* <p>
* The characters of the <code>String</code> argument are appended, in
* order, to the contents of this string buffer, increasing the
* length of this string buffer by the length of the argument.
*
* @param str a string.
* @return this string buffer.
*/
public synchronized SharedStringBuffer append(String str)
{
if (str == null)
{
str = "null";
}
int len = str.length();
int newcount = count + len;
if (newcount > value.length)
{
expandCapacity(newcount);
}
str.getChars(0, len, value, count);
count = newcount;
return this;
}
/**
* Appends the string representation of the <code>char</code> array
* argument to this string buffer.
* <p>
* The characters of the array argument are appended, in order, to
* the contents of this string buffer. The length of this string
* buffer increases by the length of the argument.
*
* @param str the characters to be appended.
* @return this string buffer.
*/
public synchronized SharedStringBuffer append(char str[])
{
int len = str.length;
int newcount = count + len;
if (newcount > value.length)
{
expandCapacity(newcount);
}
System.arraycopy(str, 0, value, count, len);
count = newcount;
return this;
}
/**
* Appends the string representation of a subarray of the
* <code>char</code> array argument to this string buffer.
* <p>
* Characters of the character array <code>str</code>, starting at
* index <code>offset</code>, are appended, in order, to the contents
* of this string buffer. The length of this string buffer increases
* by the value of <code>len</code>.
*
* @param str the characters to be appended.
* @param offset the index of the first character to append.
* @param len the number of characters to append.
* @return this string buffer.
*/
public synchronized SharedStringBuffer append(char str[], int offset, int len)
{
int newcount = count + len;
if (newcount > value.length)
{
expandCapacity(newcount);
}
System.arraycopy(str, offset, value, count, len);
count = newcount;
return this;
}
/**
* Appends the string representation of the <code>boolean</code>
* argument to the string buffer.
* <p>
* The argument is converted to a string as if by the method
* <code>String.valueOf</code>, and the characters of that
* string are then appended to this string buffer.
*
* @param b a <code>boolean</code>.
* @return this string buffer.
* @see java.lang.String#valueOf(boolean)
* @see arlut.csd.Util.SharedStringBuffer#append(java.lang.String)
*/
public SharedStringBuffer append(boolean b)
{
return append(String.valueOf(b));
}
/**
* Appends the string representation of the <code>char</code>
* argument to this string buffer.
* <p>
* The argument is appended to the contents of this string buffer.
* The length of this string buffer increases by <code>1</code>.
*
* @param c a <code>char</code>.
* @return this string buffer.
*/
public synchronized SharedStringBuffer append(char c)
{
int newcount = count + 1;
if (newcount > value.length)
{
expandCapacity(newcount);
}
value[count++] = c;
return this;
}
/**
* Appends the string representation of the <code>int</code>
* argument to this string buffer.
* <p>
* The argument is converted to a string as if by the method
* <code>String.valueOf</code>, and the characters of that
* string are then appended to this string buffer.
*
* @param i an <code>int</code>.
* @return this string buffer.
* @see java.lang.String#valueOf(int)
* @see arlut.csd.Util.SharedStringBuffer#append(java.lang.String)
*/
public SharedStringBuffer append(int i)
{
return append(String.valueOf(i));
}
/**
* Appends the string representation of the <code>long</code>
* argument to this string buffer.
* <p>
* The argument is converted to a string as if by the method
* <code>String.valueOf</code>, and the characters of that
* string are then appended to this string buffer.
*
* @param l a <code>long</code>.
* @return this string buffer.
* @see java.lang.String#valueOf(long)
* @see arlut.csd.Util.SharedStringBuffer#append(java.lang.String)
*/
public SharedStringBuffer append(long l)
{
return append(String.valueOf(l));
}
/**
* Appends the string representation of the <code>float</code>
* argument to this string buffer.
* <p>
* The argument is converted to a string as if by the method
* <code>String.valueOf</code>, and the characters of that
* string are then appended to this string buffer.
*
* @param f a <code>float</code>.
* @return this string buffer.
* @see java.lang.String#valueOf(float)
* @see arlut.csd.Util.SharedStringBuffer#append(java.lang.String)
*/
public SharedStringBuffer append(float f)
{
return append(String.valueOf(f));
}
/**
* Appends the string representation of the <code>double</code>
* argument to this string buffer.
* <p>
* The argument is converted to a string as if by the method
* <code>String.valueOf</code>, and the characters of that
* string are then appended to this string buffer.
*
* @param d a <code>double</code>.
* @return this string buffer.
* @see java.lang.String#valueOf(double)
* @see arlut.csd.Util.SharedStringBuffer#append(java.lang.String)
*/
public SharedStringBuffer append(double d)
{
return append(String.valueOf(d));
}
/**
* Inserts the string representation of the <code>Object</code>
* argument into this string buffer.
* <p>
* The second argument is converted to a string as if by the method
* <code>String.valueOf</code>, and the characters of that
* string are then inserted into this string buffer at the indicated
* offset.
* <p>
* The offset argument must be greater than or equal to
* <code>0</code>, and less than or equal to the length of this
* string buffer.
*
* @param offset the offset.
* @param obj an <code>Object</code>.
* @return this string buffer.
* @exception StringIndexOutOfBoundsException if the offset is invalid.
* @see java.lang.String#valueOf(java.lang.Object)
* @see arlut.csd.Util.SharedStringBuffer#insert(int, java.lang.String)
* @see arlut.csd.Util.SharedStringBuffer#length()
*/
public synchronized SharedStringBuffer insert(int offset, Object obj)
{
return insert(offset, String.valueOf(obj));
}
/**
* Inserts the string into this string buffer.
* <p>
* The characters of the <code>String</code> argument are inserted, in
* order, into this string buffer at the indicated offset. The length
* of this string buffer is increased by the length of the argument.
* <p>
* The offset argument must be greater than or equal to
* <code>0</code>, and less than or equal to the length of this
* string buffer.
*
* @param offset the offset.
* @param str a string.
* @return this string buffer.
* @exception StringIndexOutOfBoundsException if the offset is invalid.
* @see arlut.csd.Util.SharedStringBuffer#length()
*/
public synchronized SharedStringBuffer insert(int offset, String str)
{
if ((offset < 0) || (offset > count))
{
throw new StringIndexOutOfBoundsException();
}
int len = str.length();
int newcount = count + len;
if (newcount > value.length)
{
expandCapacity(newcount);
}
System.arraycopy(value, offset, value, offset + len, count - offset);
str.getChars(0, len, value, offset);
count = newcount;
return this;
}
/**
* Inserts the string representation of the <code>char</code> array
* argument into this string buffer.
* <p>
* The characters of the array argument are inserted into the
* contents of this string buffer at the position indicated by
* <code>offset</code>. The length of this string buffer increases by
* the length of the argument.
*
* @param offset the offset.
* @param str a character array.
* @return this string buffer.
* @exception StringIndexOutOfBoundsException if the offset is invalid.
*/
public synchronized SharedStringBuffer insert(int offset, char str[])
{
if ((offset < 0) || (offset > count))
{
throw new StringIndexOutOfBoundsException();
}
int len = str.length;
int newcount = count + len;
if (newcount > value.length)
{
expandCapacity(newcount);
}
System.arraycopy(value, offset, value, offset + len, count - offset);
System.arraycopy(str, 0, value, offset, len);
count = newcount;
return this;
}
/**
* Inserts the string representation of the <code>boolean</code>
* argument into this string buffer.
* <p>
* The second argument is converted to a string as if by the method
* <code>String.valueOf</code>, and the characters of that
* string are then inserted into this string buffer at the indicated
* offset.
* <p>
* The offset argument must be greater than or equal to
* <code>0</code>, and less than or equal to the length of this
* string buffer.
*
* @param offset the offset.
* @param b a <code>boolean</code>.
* @return this string buffer.
* @exception StringIndexOutOfBoundsException if the offset is invalid.
* @see java.lang.String#valueOf(boolean)
* @see arlut.csd.Util.SharedStringBuffer#insert(int, java.lang.String)
* @see arlut.csd.Util.SharedStringBuffer#length()
*/
public SharedStringBuffer insert(int offset, boolean b)
{
return insert(offset, String.valueOf(b));
}
/**
* Inserts the string representation of the <code>char</code>
* argument into this string buffer.
* <p>
* The second argument is inserted into the contents of this string
* buffer at the position indicated by <code>offset</code>. The length
* of this string buffer increases by one.
* <p>
* The offset argument must be greater than or equal to
* <code>0</code>, and less than or equal to the length of this
* string buffer.
*
* @param offset the offset.
* @param c a <code>char</code>.
* @return this string buffer.
* @exception StringIndexOutOfBoundsException if the offset is invalid.
* @see arlut.csd.Util.SharedStringBuffer#length()
*/
public synchronized SharedStringBuffer insert(int offset, char c)
{
int newcount = count + 1;
if (newcount > value.length)
{
expandCapacity(newcount);
}
System.arraycopy(value, offset, value, offset + 1, count - offset);
value[offset] = c;
count = newcount;
return this;
}
/**
* Inserts the string representation of the second <code>int</code>
* argument into this string buffer.
* <p>
* The second argument is converted to a string as if by the method
* <code>String.valueOf</code>, and the characters of that
* string are then inserted into this string buffer at the indicated
* offset.
* <p>
* The offset argument must be greater than or equal to
* <code>0</code>, and less than or equal to the length of this
* string buffer.
*
* @param offset the offset.
* @param i an <code>int</code>.
* @return this string buffer.
* @exception StringIndexOutOfBoundsException if the offset is invalid.
* @see java.lang.String#valueOf(int)
* @see arlut.csd.Util.SharedStringBuffer#insert(int, java.lang.String)
* @see arlut.csd.Util.SharedStringBuffer#length()
*/
public SharedStringBuffer insert(int offset, int i)
{
return insert(offset, String.valueOf(i));
}
/**
* Inserts the string representation of the <code>long</code>
* argument into this string buffer.
* <p>
* The second argument is converted to a string as if by the method
* <code>String.valueOf</code>, and the characters of that
* string are then inserted into this string buffer at the indicated
* offset.
* <p>
* The offset argument must be greater than or equal to
* <code>0</code>, and less than or equal to the length of this
* string buffer.
*
* @param offset the offset.
* @param l a <code>long</code>.
* @return this string buffer.
* @exception StringIndexOutOfBoundsException if the offset is invalid.
* @see java.lang.String#valueOf(long)
* @see arlut.csd.Util.SharedStringBuffer#insert(int, java.lang.String)
* @see arlut.csd.Util.SharedStringBuffer#length()
*/
public SharedStringBuffer insert(int offset, long l)
{
return insert(offset, String.valueOf(l));
}
/**
* Inserts the string representation of the <code>float</code>
* argument into this string buffer.
* <p>
* The second argument is converted to a string as if by the method
* <code>String.valueOf</code>, and the characters of that
* string are then inserted into this string buffer at the indicated
* offset.
* <p>
* The offset argument must be greater than or equal to
* <code>0</code>, and less than or equal to the length of this
* string buffer.
*
* @param offset the offset.
* @param f a <code>float</code>.
* @return this string buffer.
* @exception StringIndexOutOfBoundsException if the offset is invalid.
* @see java.lang.String#valueOf(float)
* @see arlut.csd.Util.SharedStringBuffer#insert(int, java.lang.String)
* @see arlut.csd.Util.SharedStringBuffer#length()
*/
public SharedStringBuffer insert(int offset, float f)
{
return insert(offset, String.valueOf(f));
}
/**
* Inserts the string representation of the <code>double</code>
* argument into this string buffer.
* <p>
* The second argument is converted to a string as if by the method
* <code>String.valueOf</code>, and the characters of that
* string are then inserted into this string buffer at the indicated
* offset.
* <p>
* The offset argument must be greater than or equal to
* <code>0</code>, and less than or equal to the length of this
* string buffer.
*
* @param offset the offset.
* @param d a <code>double</code>.
* @return this string buffer.
* @exception StringIndexOutOfBoundsException if the offset is invalid.
* @see java.lang.String#valueOf(double)
* @see arlut.csd.Util.SharedStringBuffer#insert(int, java.lang.String)
* @see arlut.csd.Util.SharedStringBuffer#length()
*/
public SharedStringBuffer insert(int offset, double d)
{
return insert(offset, String.valueOf(d));
}
/**
* The character sequence contained in this string buffer is
* replaced by the reverse of the sequence.
*
* @return this string buffer.
*/
public synchronized SharedStringBuffer reverse()
{
int n = count - 1;
for (int j = (n-1) >> 1; j >= 0; --j)
{
char temp = value[j];
value[j] = value[n - j];
value[n - j] = temp;
}
return this;
}
/**
* Converts to a string representing the data in this string buffer.
* A new <code>String</code> object is allocated and initialized to
* contain the character sequence currently represented by this
* string buffer. This <code>String</code> is then returned. Subsequent
* changes to the string buffer do not affect the contents of the
* <code>String</code>.
*
* @return a string representation of the string buffer.
*/
public String toString()
{
return new String(value, 0, count);
}
/**
*
* Return direct access to the char[] array in this object. It is
* the responsibility of the calling code to make sure that it is
* executing in a context in which no other code will touch this
* array or SharedStringBuffer while the the reference to this
* array is in use.
*
*/
public final char[] getValue()
{
return value.clone();
}
}