https://tomcat.apache.org/: Common code shared by multiple Tomcat components 
/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.apache.tomcat.util.buf;

import java.io.IOException;


Utilities to manipulate char chunks. While String is the easiest way to
manipulate chars ( search, substrings, etc), it is known to not be the most
efficient solution - Strings are designed as immutable and secure objects.

Author:dac@sun.com, James Todd [gonzo@sun.com], Costin Manolache, Remy Maucherat
/**
 * Utilities to manipulate char chunks. While String is the easiest way to
 * manipulate chars ( search, substrings, etc), it is known to not be the most
 * efficient solution - Strings are designed as immutable and secure objects.
 *
 * @author dac@sun.com
 * @author James Todd [gonzo@sun.com]
 * @author Costin Manolache
 * @author Remy Maucherat
 */
public final class CharChunk extends AbstractChunk implements CharSequence {

    private static final long serialVersionUID = 1L;

    
Input interface, used when the buffer is empty.

/**
     * Input interface, used when the buffer is empty.
     */
    public static interface CharInputChannel {

        
Read new characters.

Throws:
Returns:The number of characters read
/**
         * Read new characters.
         *
         * @return The number of characters read
         *
         * @throws IOException If an I/O error occurs during reading
         */
        public int realReadChars() throws IOException;
    }

    
When we need more space we'll either grow the buffer ( up to the limit )
or send it to a channel.

/**
     * When we need more space we'll either grow the buffer ( up to the limit )
     * or send it to a channel.
     */
    public static interface CharOutputChannel {

        
Send the bytes ( usually the internal conversion buffer ). Expect 8k
output if the buffer is full.

Params:
  • buf – characters that will be written
  • off – offset in the characters array
  • len – length that will be written
Throws:
  • IOException – If an I/O occurs while writing the characters
/**
         * Send the bytes ( usually the internal conversion buffer ). Expect 8k
         * output if the buffer is full.
         *
         * @param buf characters that will be written
         * @param off offset in the characters array
         * @param len length that will be written
         * @throws IOException If an I/O occurs while writing the characters
         */
        public void realWriteChars(char buf[], int off, int len) throws IOException;
    }

    // --------------------

    // char[]
    private char[] buff;

    // transient as serialization is primarily for values via, e.g. JMX
    private transient CharInputChannel in = null;
    private transient CharOutputChannel out = null;


    
Creates a new, uninitialized CharChunk object.

/**
     * Creates a new, uninitialized CharChunk object.
     */
    public CharChunk() {
    }


    public CharChunk(int initial) {
        allocate(initial, -1);
    }


    // --------------------

    @Override
    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }


    // -------------------- Setup --------------------

    public void allocate(int initial, int limit) {
        if (buff == null || buff.length < initial) {
            buff = new char[initial];
        }
        setLimit(limit);
        start = 0;
        end = 0;
        isSet = true;
        hasHashCode = false;
    }


    
Sets the buffer to the specified subarray of characters.

Params:
  • c – the characters
  • off – the start offset of the characters
  • len – the length of the characters
/**
     * Sets the buffer to the specified subarray of characters.
     *
     * @param c the characters
     * @param off the start offset of the characters
     * @param len the length of the characters
     */
    public void setChars(char[] c, int off, int len) {
        buff = c;
        start = off;
        end = start + len;
        isSet = true;
        hasHashCode = false;
    }


    
Returns:the buffer.
/**
     * @return the buffer.
     */
    public char[] getChars() {
        return getBuffer();
    }


    
Returns:the buffer.
/**
     * @return the buffer.
     */
    public char[] getBuffer() {
        return buff;
    }


    
When the buffer is empty, read the data from the input channel.

Params:
  • in – The input channel
/**
     * When the buffer is empty, read the data from the input channel.
     *
     * @param in The input channel
     */
    public void setCharInputChannel(CharInputChannel in) {
        this.in = in;
    }


    
When the buffer is full, write the data to the output channel. Also used
when large amount of data is appended. If not set, the buffer will grow
to the limit.

Params:
  • out – The output channel
/**
     * When the buffer is full, write the data to the output channel. Also used
     * when large amount of data is appended. If not set, the buffer will grow
     * to the limit.
     *
     * @param out The output channel
     */
    public void setCharOutputChannel(CharOutputChannel out) {
        this.out = out;
    }


    // -------------------- Adding data to the buffer --------------------

    public void append(char b) throws IOException {
        makeSpace(1);
        int limit = getLimitInternal();

        // couldn't make space
        if (end >= limit) {
            flushBuffer();
        }
        buff[end++] = b;
    }


    public void append(CharChunk src) throws IOException {
        append(src.getBuffer(), src.getOffset(), src.getLength());
    }


    
Add data to the buffer.

Params:
  • src – Char array
  • off – Offset
  • len – Length
Throws:
  • IOException – Writing overflow data to the output channel failed
/**
     * Add data to the buffer.
     *
     * @param src Char array
     * @param off Offset
     * @param len Length
     * @throws IOException Writing overflow data to the output channel failed
     */
    public void append(char src[], int off, int len) throws IOException {
        // will grow, up to limit
        makeSpace(len);
        int limit = getLimitInternal();

        // Optimize on a common case.
        // If the buffer is empty and the source is going to fill up all the
        // space in buffer, may as well write it directly to the output,
        // and avoid an extra copy
        if (len == limit && end == start && out != null) {
            out.realWriteChars(src, off, len);
            return;
        }

        // if we are below the limit
        if (len <= limit - end) {
            System.arraycopy(src, off, buff, end, len);
            end += len;
            return;
        }

        // Need more space than we can afford, need to flush buffer.

        // The buffer is already at (or bigger than) limit.

        // Optimization:
        // If len-avail < length (i.e. after we fill the buffer with what we
        // can, the remaining will fit in the buffer) we'll just copy the first
        // part, flush, then copy the second part - 1 write and still have some
        // space for more. We'll still have 2 writes, but we write more on the first.

        if (len + end < 2 * limit) {
            /*
             * If the request length exceeds the size of the output buffer,
             * flush the output buffer and then write the data directly. We
             * can't avoid 2 writes, but we can write more on the second
             */
            int avail = limit - end;
            System.arraycopy(src, off, buff, end, avail);
            end += avail;

            flushBuffer();

            System.arraycopy(src, off + avail, buff, end, len - avail);
            end += len - avail;

        } else { // len > buf.length + avail
            // long write - flush the buffer and write the rest
            // directly from source
            flushBuffer();

            out.realWriteChars(src, off, len);
        }
    }


    
Append a string to the buffer.

Params:
  • s – The string
Throws:
  • IOException – Writing overflow data to the output channel failed
/**
     * Append a string to the buffer.
     *
     * @param s The string
     * @throws IOException Writing overflow data to the output channel failed
     */
    public void append(String s) throws IOException {
        append(s, 0, s.length());
    }


    
Append a string to the buffer.

Params:
  • s – The string
  • off – Offset
  • len – Length
Throws:
  • IOException – Writing overflow data to the output channel failed
/**
     * Append a string to the buffer.
     *
     * @param s The string
     * @param off Offset
     * @param len Length
     * @throws IOException Writing overflow data to the output channel failed
     */
    public void append(String s, int off, int len) throws IOException {
        if (s == null) {
            return;
        }

        // will grow, up to limit
        makeSpace(len);
        int limit = getLimitInternal();

        int sOff = off;
        int sEnd = off + len;
        while (sOff < sEnd) {
            int d = min(limit - end, sEnd - sOff);
            s.getChars(sOff, sOff + d, buff, end);
            sOff += d;
            end += d;
            if (end >= limit) {
                flushBuffer();
            }
        }
    }


    // -------------------- Removing data from the buffer --------------------

    /*
     * @deprecated Use {@link #subtract()}.
     *             This method will be removed in Tomcat 10
     */
    @Deprecated
    public int substract() throws IOException {
        return subtract();
    }

    public int subtract() throws IOException {
        if (checkEof()) {
            return -1;
        }
        return buff[start++];
    }


    /*
     * @deprecated Use {@link #subtract(char[],int,int)}.
     *             This method will be removed in Tomcat 10
     */
    @Deprecated
    public int substract(char dest[], int off, int len) throws IOException {
        return subtract(dest, off, len);
    }

    public int subtract(char dest[], int off, int len) throws IOException {
        if (checkEof()) {
            return -1;
        }
        int n = len;
        if (len > getLength()) {
            n = getLength();
        }
        System.arraycopy(buff, start, dest, off, n);
        start += n;
        return n;
    }


    private boolean checkEof() throws IOException {
        if ((end - start) == 0) {
            if (in == null) {
                return true;
            }
            int n = in.realReadChars();
            if (n < 0) {
                return true;
            }
        }
        return false;
    }


    
Send the buffer to the sink. Called by append() when the limit is
reached. You can also call it explicitly to force the data to be written.

Throws:
  • IOException – Writing overflow data to the output channel failed
/**
     * Send the buffer to the sink. Called by append() when the limit is
     * reached. You can also call it explicitly to force the data to be written.
     *
     * @throws IOException Writing overflow data to the output channel failed
     */
    public void flushBuffer() throws IOException {
        // assert out!=null
        if (out == null) {
            throw new IOException(sm.getString("chunk.overflow",
                    Integer.valueOf(getLimit()), Integer.valueOf(buff.length)));
        }
        out.realWriteChars(buff, start, end - start);
        end = start;
    }


    
Make space for len chars. If len is small, allocate a reserve space too. Never grow bigger than the limit or AbstractChunk.ARRAY_MAX_SIZE. 
Params:
  • count – The size
/**
     * Make space for len chars. If len is small, allocate a reserve space too.
     * Never grow bigger than the limit or {@link AbstractChunk#ARRAY_MAX_SIZE}.
     *
     * @param count The size
     */
    public void makeSpace(int count) {
        char[] tmp = null;

        int limit = getLimitInternal();

        long newSize;
        long desiredSize = end + count;

        // Can't grow above the limit
        if (desiredSize > limit) {
            desiredSize = limit;
        }

        if (buff == null) {
            if (desiredSize < 256) {
                desiredSize = 256; // take a minimum
            }
            buff = new char[(int) desiredSize];
        }

        // limit < buf.length (the buffer is already big)
        // or we already have space XXX
        if (desiredSize <= buff.length) {
            return;
        }
        // grow in larger chunks
        if (desiredSize < 2L * buff.length) {
            newSize = buff.length * 2L;
        } else {
            newSize = buff.length * 2L + count;
        }

        if (newSize > limit) {
            newSize = limit;
        }
        tmp = new char[(int) newSize];

        // Some calling code assumes buffer will not be compacted
        System.arraycopy(buff, 0, tmp, 0, end);
        buff = tmp;
        tmp = null;
    }


    // -------------------- Conversion and getters --------------------

    @Override
    public String toString() {
        if (isNull()) {
            return null;
        } else if (end - start == 0) {
            return "";
        }
        return StringCache.toString(this);
    }


    public String toStringInternal() {
        return new String(buff, start, end - start);
    }


    // -------------------- equals --------------------

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof CharChunk) {
            return equals((CharChunk) obj);
        }
        return false;
    }


    
Compares the message bytes to the specified String object.

Params:
  • s – the String to compare
Returns:true if the comparison succeeded, false
        otherwise
/**
     * Compares the message bytes to the specified String object.
     *
     * @param s the String to compare
     * @return <code>true</code> if the comparison succeeded, <code>false</code>
     *         otherwise
     */
    public boolean equals(String s) {
        char[] c = buff;
        int len = end - start;
        if (c == null || len != s.length()) {
            return false;
        }
        int off = start;
        for (int i = 0; i < len; i++) {
            if (c[off++] != s.charAt(i)) {
                return false;
            }
        }
        return true;
    }


    
Compares the message bytes to the specified String object.

Params:
  • s – the String to compare
Returns:true if the comparison succeeded, false
        otherwise
/**
     * Compares the message bytes to the specified String object.
     *
     * @param s the String to compare
     * @return <code>true</code> if the comparison succeeded, <code>false</code>
     *         otherwise
     */
    public boolean equalsIgnoreCase(String s) {
        char[] c = buff;
        int len = end - start;
        if (c == null || len != s.length()) {
            return false;
        }
        int off = start;
        for (int i = 0; i < len; i++) {
            if (Ascii.toLower(c[off++]) != Ascii.toLower(s.charAt(i))) {
                return false;
            }
        }
        return true;
    }


    public boolean equals(CharChunk cc) {
        return equals(cc.getChars(), cc.getOffset(), cc.getLength());
    }


    public boolean equals(char b2[], int off2, int len2) {
        char b1[] = buff;
        if (b1 == null && b2 == null) {
            return true;
        }

        int len = end - start;
        if (len != len2 || b1 == null || b2 == null) {
            return false;
        }

        int off1 = start;

        while (len-- > 0) {
            if (b1[off1++] != b2[off2++]) {
                return false;
            }
        }
        return true;
    }


    
Params:
  • s – The string
Returns:true if the message bytes starts with the specified
        string.
/**
     * @return <code>true</code> if the message bytes starts with the specified
     *         string.
     * @param s The string
     */
    public boolean startsWith(String s) {
        char[] c = buff;
        int len = s.length();
        if (c == null || len > end - start) {
            return false;
        }
        int off = start;
        for (int i = 0; i < len; i++) {
            if (c[off++] != s.charAt(i)) {
                return false;
            }
        }
        return true;
    }


    
Returns true if the buffer starts with the specified string.

Params:
  • s – the string
  • pos – The position
Returns:true if the start matches
/**
     * Returns true if the buffer starts with the specified string.
     *
     * @param s the string
     * @param pos The position
     *
     * @return <code>true</code> if the start matches
     */
    public boolean startsWithIgnoreCase(String s, int pos) {
        char[] c = buff;
        int len = s.length();
        if (c == null || len + pos > end - start) {
            return false;
        }
        int off = start + pos;
        for (int i = 0; i < len; i++) {
            if (Ascii.toLower(c[off++]) != Ascii.toLower(s.charAt(i))) {
                return false;
            }
        }
        return true;
    }


    
Params:
  • s – The string
Returns:true if the message bytes end with the specified
        string.
/**
     * @return <code>true</code> if the message bytes end with the specified
     *         string.
     * @param s The string
     */
    public boolean endsWith(String s) {
        char[] c = buff;
        int len = s.length();
        if (c == null || len > end - start) {
            return false;
        }
        int off = end - len;
        for (int i = 0; i < len; i++) {
            if (c[off++] != s.charAt(i)) {
                return false;
            }
        }
        return true;
    }


    @Override
    protected int getBufferElement(int index) {
        return buff[index];
    }


    public int indexOf(char c) {
        return indexOf(c, start);
    }


    
Returns the first instance of the given character in this CharChunk
starting at the specified char. If the character is not found, -1 is
returned. 


Params:
  • c – The character
  • starting – The start position
Returns:The position of the first instance of the character or -1 if the
        character is not found.
/**
     * Returns the first instance of the given character in this CharChunk
     * starting at the specified char. If the character is not found, -1 is
     * returned. <br>
     *
     * @param c The character
     * @param starting The start position
     * @return The position of the first instance of the character or -1 if the
     *         character is not found.
     */
    public int indexOf(char c, int starting) {
        int ret = indexOf(buff, start + starting, end, c);
        return (ret >= start) ? ret - start : -1;
    }


    
Returns the first instance of the given character in the given char array
between the specified start and end. 


Params:
  • chars – The array to search
  • start – The point to start searching from in the array
  • end – The point to stop searching in the array
  • s – The character to search for
Returns:The position of the first instance of the character or -1 if the
        character is not found.
/**
     * Returns the first instance of the given character in the given char array
     * between the specified start and end. <br>
     *
     * @param chars The array to search
     * @param start The point to start searching from in the array
     * @param end The point to stop searching in the array
     * @param s The character to search for
     * @return The position of the first instance of the character or -1 if the
     *         character is not found.
     */
    public static int indexOf(char chars[], int start, int end, char s) {
        int offset = start;

        while (offset < end) {
            char c = chars[offset];
            if (c == s) {
                return offset;
            }
            offset++;
        }
        return -1;
    }


    // -------------------- utils
    private int min(int a, int b) {
        if (a < b) {
            return a;
        }
        return b;
    }


    // Char sequence impl

    @Override
    public char charAt(int index) {
        return buff[index + start];
    }


    @Override
    public CharSequence subSequence(int start, int end) {
        try {
            CharChunk result = (CharChunk) this.clone();
            result.setOffset(this.start + start);
            result.setEnd(this.start + end);
            return result;
        } catch (CloneNotSupportedException e) {
            // Cannot happen
            return null;
        }
    }


    @Override
    public int length() {
        return end - start;
    }

    
NO-OP.

Params:
  • optimizedWrite – Ignored
Deprecated:Unused code. This is now a NO-OP and will be removed without
            replacement in Tomcat 10.
/**
     * NO-OP.
     *
     * @param optimizedWrite Ignored
     *
     * @deprecated Unused code. This is now a NO-OP and will be removed without
     *             replacement in Tomcat 10.
     */
    @Deprecated
    public void setOptimizedWrite(boolean optimizedWrite) {
    }
}