appendingstringbuffer.java

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	 * equal to the length of this string buffer.
	 * 
	 * @param offset
	 *            the offset.
	 * @param d
	 *            a <code>double</code>.
	 * @return a reference to this <code>AppendingStringBuffer</code> object.
	 * @exception StringIndexOutOfBoundsException
	 *                if the offset is invalid.
	 * @see java.lang.String#valueOf(double)
	 * @see java.lang.StringBuffer#insert(int, java.lang.String)
	 * @see java.lang.StringBuffer#length()
	 */
	public AppendingStringBuffer insert(int offset, double d)
	{
		return insert(offset, String.valueOf(d));
	}

	/**
	 * Returns the index within this string of the first occurrence of the specified substring. The
	 * integer returned is the smallest value <i>k</i> such that: <blockquote>
	 * 
	 * <pre>
	 *       this.toString().startsWith(str, &lt;i&gt;k&lt;/i&gt;)
	 * </pre>
	 * 
	 * </blockquote> is <code>true</code>.
	 * 
	 * @param str
	 *            any string.
	 * @return if the string argument occurs as a substring within this object, then the index of
	 *         the first character of the first such substring is returned; if it does not occur as
	 *         a substring, <code>-1</code> is returned.
	 * @exception java.lang.NullPointerException
	 *                if <code>str</code> is <code>null</code>.
	 * @since 1.4
	 */
	public int indexOf(String str)
	{
		return indexOf(str, 0);
	}

	/**
	 * Returns the index within this string of the first occurrence of the specified substring,
	 * starting at the specified index. The integer returned is the smallest value <tt>k</tt> for
	 * which: <blockquote>
	 * 
	 * <pre>
	 * k &gt;= Math.min(fromIndex, str.length()) &amp;&amp; this.toString().startsWith(str, k)
	 * </pre>
	 * 
	 * </blockquote> If no such value of <i>k</i> exists, then -1 is returned.
	 * 
	 * @param str
	 *            the substring for which to search.
	 * @param fromIndex
	 *            the index from which to start the search.
	 * @return the index within this string of the first occurrence of the specified substring,
	 *         starting at the specified index.
	 * @exception java.lang.NullPointerException
	 *                if <code>str</code> is <code>null</code>.
	 * @since 1.4
	 */
	public int indexOf(String str, int fromIndex)
	{
		return indexOf(value, 0, count, str.toCharArray(), 0, str.length(), fromIndex);
	}

	static int indexOf(char[] source, int sourceOffset, int sourceCount, char[] target,
			int targetOffset, int targetCount, int fromIndex)
	{
		if (fromIndex >= sourceCount)
		{
			return (targetCount == 0 ? sourceCount : -1);
		}
		if (fromIndex < 0)
		{
			fromIndex = 0;
		}
		if (targetCount == 0)
		{
			return fromIndex;
		}

		char first = target[targetOffset];
		int i = sourceOffset + fromIndex;
		int max = sourceOffset + (sourceCount - targetCount);

		startSearchForFirstChar : while (true)
		{
			/* Look for first character. */
			while (i <= max && source[i] != first)
			{
				i++;
			}
			if (i > max)
			{
				return -1;
			}

			/* Found first character, now look at the rest of v2 */
			int j = i + 1;
			int end = j + targetCount - 1;
			int k = targetOffset + 1;
			while (j < end)
			{
				if (source[j++] != target[k++])
				{
					i++;
					/* Look for str's first char again. */
					continue startSearchForFirstChar;
				}
			}
			return i - sourceOffset; /* Found whole string. */
		}
	}

	/**
	 * Returns the index within this string of the rightmost occurrence of the specified substring.
	 * The rightmost empty string "" is considered to occur at the index value
	 * <code>this.length()</code>. The returned index is the largest value <i>k</i> such that
	 * <blockquote>
	 * 
	 * <pre>
	 * this.toString().startsWith(str, k)
	 * </pre>
	 * 
	 * </blockquote> is true.
	 * 
	 * @param str
	 *            the substring to search for.
	 * @return if the string argument occurs one or more times as a substring within this object,
	 *         then the index of the first character of the last such substring is returned. If it
	 *         does not occur as a substring, <code>-1</code> is returned.
	 * @exception java.lang.NullPointerException
	 *                if <code>str</code> is <code>null</code>.
	 * @since 1.4
	 */
	public int lastIndexOf(String str)
	{
		return lastIndexOf(str, count);
	}

	/**
	 * Returns the index within this string of the last occurrence of the specified substring. The
	 * integer returned is the largest value <i>k</i> such that: <blockquote>
	 * 
	 * <pre>
	 * k &lt;= Math.min(fromIndex, str.length()) &amp;&amp; this.toString().startsWith(str, k)
	 * </pre>
	 * 
	 * </blockquote> If no such value of <i>k</i> exists, then -1 is returned.
	 * 
	 * @param str
	 *            the substring to search for.
	 * @param fromIndex
	 *            the index to start the search from.
	 * @return the index within this string of the last occurrence of the specified substring.
	 * @exception java.lang.NullPointerException
	 *                if <code>str</code> is <code>null</code>.
	 * @since 1.4
	 */
	public int lastIndexOf(String str, int fromIndex)
	{
		return lastIndexOf(value, 0, count, str.toCharArray(), 0, str.length(), fromIndex);
	}

	static int lastIndexOf(char[] source, int sourceOffset, int sourceCount, char[] target,
			int targetOffset, int targetCount, int fromIndex)
	{
		/*
		 * Check arguments; return immediately where possible. For consistency, don't check for null
		 * str.
		 */
		int rightIndex = sourceCount - targetCount;
		if (fromIndex < 0)
		{
			return -1;
		}
		if (fromIndex > rightIndex)
		{
			fromIndex = rightIndex;
		}
		/* Empty string always matches. */
		if (targetCount == 0)
		{
			return fromIndex;
		}

		int strLastIndex = targetOffset + targetCount - 1;
		char strLastChar = target[strLastIndex];
		int min = sourceOffset + targetCount - 1;
		int i = min + fromIndex;

		startSearchForLastChar : while (true)
		{
			while (i >= min && source[i] != strLastChar)
			{
				i--;
			}
			if (i < min)
			{
				return -1;
			}
			int j = i - 1;
			int start = j - (targetCount - 1);
			int k = strLastIndex - 1;

			while (j > start)
			{
				if (source[j--] != target[k--])
				{
					i--;
					continue startSearchForLastChar;
				}
			}
			return start - sourceOffset + 1;
		}
	}

	/**
	 * Tests if this AppendingStringBuffer starts with the specified prefix beginning a specified
	 * index.
	 * 
	 * @param prefix
	 *            the prefix.
	 * @param toffset
	 *            where to begin looking in the string.
	 * @return <code>true</code> if the character sequence represented by the argument is a prefix
	 *         of the substring of this object starting at index <code>toffset</code>;
	 *         <code>false</code> otherwise. The result is <code>false</code> if
	 *         <code>toffset</code> is negative or greater than the length of this
	 *         <code>String</code> object; otherwise the result is the same as the result of the
	 *         expression
	 * 
	 * <pre>
	 * this.subString(toffset).startsWith(prefix)
	 * </pre>
	 */
	public boolean startsWith(CharSequence prefix, int toffset)
	{
		char ta[] = value;
		int to = toffset;
		int po = 0;
		int pc = prefix.length();
		// Note: toffset might be near -1>>>1.
		if ((toffset < 0) || (toffset > count - pc))
		{
			return false;
		}
		while (--pc >= 0)
		{
			if (ta[to++] != prefix.charAt(po++))
			{
				return false;
			}
		}
		return true;
	}

	/**
	 * Tests if this AppendingStringBuffer starts with the specified prefix.
	 * 
	 * @param prefix
	 *            the prefix.
	 * @return <code>true</code> if the character sequence represented by the argument is a prefix
	 *         of the character sequence represented by this AppendingStringBuffer;
	 *         <code>false</code> otherwise. Note also that <code>true</code> will be returned
	 *         if the argument is an empty string or is equal to this
	 *         <code>AppendingStringBuffer</code> object as determined by the
	 *         {@link #equals(Object)} method.
	 * @since 1. 0
	 */
	public boolean startsWith(CharSequence prefix)
	{
		return startsWith(prefix, 0);
	}

	/**
	 * Tests if this AppendingStringBuffer ends with the specified suffix.
	 * 
	 * @param suffix
	 *            the suffix.
	 * @return <code>true</code> if the character sequence represented by the argument is a suffix
	 *         of the character sequence represented by this AppendingStringBuffer;
	 *         <code>false</code> otherwise. Note that the result will be <code>true</code> if
	 *         the argument is the empty string or is equal to this
	 *         <code>AppendingStringBuffer</code> object as determined by the
	 *         {@link #equals(Object)} method.
	 */
	public boolean endsWith(CharSequence suffix)
	{
		return startsWith(suffix, count - suffix.length());
	}

	/**
	 * Converts to a string representing the data in this AppendingStringBuffer. 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>.
	 * <p>
	 * Implementation advice: This method can be coded so as to create a new <code>String</code>
	 * object without allocating new memory to hold a copy of the character sequence. Instead, the
	 * string can share the memory used by the string buffer. Any subsequent operation that alters
	 * the content or capacity of the string buffer must then make a copy of the internal buffer at
	 * that time. This strategy is effective for reducing the amount of memory allocated by a string
	 * concatenation operation when it is implemented using a string buffer.
	 * 
	 * @return a string representation of the string buffer.
	 */
	public String toString()
	{
		return new String(this.value, 0, count);
	}

	/**
	 * This method returns the internal char array. So it is not
	 * 
	 * @return The internal char array
	 */
	public final char[] getValue()
	{
		return value;
	}


	/**
	 * readObject is called to restore the state of the AppendingStringBuffer from a stream.
	 * 
	 * @param s
	 * @throws ClassNotFoundException
	 * @throws IOException
	 */
	private void readObject(java.io.ObjectInputStream s) throws IOException, ClassNotFoundException
	{
		s.defaultReadObject();
		value = (char[])value.clone();
	}

	/**
	 * Compares this AppendingStringBuffer to the specified object. The result is <code>true</code>
	 * if and only if the argument is not <code>null</code> and is a
	 * <code>AppendingStringBuffer</code> object or another charsequence object! that represents
	 * the same sequence of characters as this object.
	 * 
	 * @param anObject
	 *            the object to compare this <code>AppendingStringBuffer</code> against.
	 * @return <code>true</code> if the <code>AppendingStringBuffer</code>are equal;
	 *         <code>false</code> otherwise.
	 */
	public boolean equals(Object anObject)
	{
		if (this == anObject)
		{
			return true;
		}
		if (anObject instanceof AppendingStringBuffer)
		{
			AppendingStringBuffer anotherString = (AppendingStringBuffer)anObject;
			int n = count;
			if (n == anotherString.count)
			{
				char v1[] = value;
				char v2[] = anotherString.value;
				int i = 0;
				while (n-- != 0)
				{
					if (v1[i] != v2[i++])
					{
						return false;
					}
				}
				return true;
			}
		}
		else if (anObject instanceof CharSequence)
		{
			CharSequence sequence = (CharSequence)anObject;
			int n = count;
			if (sequence.length() == count)
			{
				char v1[] = value;
				int i = 0;
				while (n-- != 0)
				{
					if (v1[i] != sequence.charAt(i++))
					{
						return false;
					}
				}
				return true;
			}
		}
		return false;
	}

	/**
	 * Returns a hash code for this AppendingStringBuffer. The hash code for a
	 * <code>AppendingStringBuffer</code> object is computed as <blockquote>
	 * 
	 * <pre>
	 *    s[0]*31&circ;(n-1) + s[1]*31&circ;(n-2) + ... + s[n-1]
	 * </pre>
	 * 
	 * </blockquote> using <code>int</code> arithmetic, where <code>s[i]</code> is the <i>i</i>th
	 * character of the AppendingStringBuffer, <code>n</code> is the length of the
	 * AppendingStringBuffer, and <code>^</code> indicates exponentiation. (The hash value of the
	 * empty AppendingStringBuffer is zero.)
	 * 
	 * @return a hash code value for this object.
	 */
	public int hashCode()
	{
		int h = 0;
		if (h == 0)
		{
			int off = 0;
			char val[] = value;
			int len = count;

			for (int i = 0; i < len; i++)
			{
				h = 31 * h + val[off++];
			}
		}
		return h;
	}

	/**
	 * Clears the buffer contents, but leaves the allocated size intact
	 */
	public void clear()
	{
		count = 0;
	}
}