/*

 * Copyright (c) 2005, 2009, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

/*

 *******************************************************************************

 * (C) Copyright IBM Corp. and others, 1996-2009 - All Rights Reserved         *

 *                                                                             *

 * The original version of this source code and documentation is copyrighted   *

 * and owned by IBM, These materials are provided under terms of a License     *

 * Agreement between IBM and Sun. This technology is protected by multiple     *

 * US and International patents. This notice and attribution to IBM may not    *

 * to removed.                                                                 *

 *******************************************************************************

 */

package sun.text.normalizer;

public final class Utility {

    /**

     * Convenience utility to compare two Object[]s

     * Ought to be in System.

     * @param len the length to compare.

     * The start indices and start+len must be valid.

     */

    public final static boolean arrayRegionMatches(char[] source, int sourceStart,

                                            char[] target, int targetStart,

                                            int len)

    {

        int sourceEnd = sourceStart + len;

        int delta = targetStart - sourceStart;

        for (int i = sourceStart; i < sourceEnd; i++) {

            if (source[i]!=target[i + delta])

            return false;

        }

        return true;

    }

    /**

     * Convert characters outside the range U+0020 to U+007F to

     * Unicode escapes, and convert backslash to a double backslash.

     */

    public static final String escape(String s) {

        StringBuffer buf = new StringBuffer();

        for (int i=0; i<s.length(); ) {

            int c = UTF16.charAt(s, i);

            i += UTF16.getCharCount(c);

            if (c >= ' ' && c <= 0x007F) {

                if (c == '\\') {

                    buf.append("\\\\"); // That is, "\\"

                } else {

                    buf.append((char)c);

                }

            } else {

                boolean four = c <= 0xFFFF;

                buf.append(four ? "\\u" : "\\U");

                hex(c, four ? 4 : 8, buf);

            }

        }

        return buf.toString();

    }

    /* This map must be in ASCENDING ORDER OF THE ESCAPE CODE */

    static private final char[] UNESCAPE_MAP = {

        /*"   0x22, 0x22 */

        /*'   0x27, 0x27 */

        /*?   0x3F, 0x3F */

        /*\   0x5C, 0x5C */

        /*a*/ 0x61, 0x07,

        /*b*/ 0x62, 0x08,

        /*e*/ 0x65, 0x1b,

        /*f*/ 0x66, 0x0c,

        /*n*/ 0x6E, 0x0a,

        /*r*/ 0x72, 0x0d,

        /*t*/ 0x74, 0x09,

        /*v*/ 0x76, 0x0b

    };

    /**

     * Convert an escape to a 32-bit code point value.  We attempt

     * to parallel the icu4c unescapeAt() function.

     * @param offset16 an array containing offset to the character

     * <em>after</em> the backslash.  Upon return offset16[0] will

     * be updated to point after the escape sequence.

     * @return character value from 0 to 10FFFF, or -1 on error.

     */

    public static int unescapeAt(String s, int[] offset16) {

        int c;

        int result = 0;

        int n = 0;

        int minDig = 0;

        int maxDig = 0;

        int bitsPerDigit = 4;

        int dig;

        int i;

        boolean braces = false;

        /* Check that offset is in range */

        int offset = offset16[0];

        int length = s.length();

        if (offset < 0 || offset >= length) {

            return -1;

        }

        /* Fetch first UChar after '\\' */

        c = UTF16.charAt(s, offset);

        offset += UTF16.getCharCount(c);

        /* Convert hexadecimal and octal escapes */

        switch (c) {

        case 'u':

            minDig = maxDig = 4;

            break;

        case 'U':

            minDig = maxDig = 8;

            break;

        case 'x':

            minDig = 1;

            if (offset < length && UTF16.charAt(s, offset) == 0x7B /*{*/) {

                ++offset;

                braces = true;

                maxDig = 8;

            } else {

                maxDig = 2;

            }

            break;

        default:

            dig = UCharacter.digit(c, 8);

            if (dig >= 0) {

                minDig = 1;

                maxDig = 3;

                n = 1; /* Already have first octal digit */

                bitsPerDigit = 3;

                result = dig;

            }

            break;

        }

        if (minDig != 0) {

            while (offset < length && n < maxDig) {

                c = UTF16.charAt(s, offset);

                dig = UCharacter.digit(c, (bitsPerDigit == 3) ? 8 : 16);

                if (dig < 0) {

                    break;

                }

                result = (result << bitsPerDigit) | dig;

                offset += UTF16.getCharCount(c);

                ++n;

            }

            if (n < minDig) {

                return -1;

            }

            if (braces) {

                if (c != 0x7D /*}*/) {

                    return -1;

                }

                ++offset;

            }

            if (result < 0 || result >= 0x110000) {

                return -1;

            }

            // If an escape sequence specifies a lead surrogate, see

            // if there is a trail surrogate after it, either as an

            // escape or as a literal.  If so, join them up into a

            // supplementary.

            if (offset < length &&

                UTF16.isLeadSurrogate((char) result)) {

                int ahead = offset+1;

                c = s.charAt(offset); // [sic] get 16-bit code unit

                if (c == '\\' && ahead < length) {

                    int o[] = new int[] { ahead };

                    c = unescapeAt(s, o);

                    ahead = o[0];

                }

                if (UTF16.isTrailSurrogate((char) c)) {

                    offset = ahead;

                result = UCharacterProperty.getRawSupplementary(

                                  (char) result, (char) c);

                }

            }

            offset16[0] = offset;

            return result;

        }

        /* Convert C-style escapes in table */

        for (i=0; i<UNESCAPE_MAP.length; i+=2) {

            if (c == UNESCAPE_MAP[i]) {

                offset16[0] = offset;

                return UNESCAPE_MAP[i+1];

            } else if (c < UNESCAPE_MAP[i]) {

                break;

            }

        }

        /* Map \cX to control-X: X & 0x1F */

        if (c == 'c' && offset < length) {

            c = UTF16.charAt(s, offset);

            offset16[0] = offset + UTF16.getCharCount(c);

            return 0x1F & c;

        }

        /* If no special forms are recognized, then consider

         * the backslash to generically escape the next character. */

        offset16[0] = offset;

        return c;

    }

    /**

     * Convert a integer to size width hex uppercase digits.

     * Append the output to the given StringBuffer.

     * If width is too small to fit, nothing will be appended to output.

     */

    public static StringBuffer hex(int ch, int width, StringBuffer output) {

        return appendNumber(output, ch, 16, width);

    }

    /**

     * Convert a integer to size width (minimum) hex uppercase digits.

     * than width digits, more will be used.

     */

    public static String hex(int ch, int width) {

        StringBuffer buf = new StringBuffer();

        return appendNumber(buf, ch, 16, width).toString();

    }

    /**

     * Skip over a sequence of zero or more white space characters

     * at pos.  Return the index of the first non-white-space character

     * at or after pos, or str.length(), if there is none.

     */

    public static int skipWhitespace(String str, int pos) {

        while (pos < str.length()) {

            int c = UTF16.charAt(str, pos);

            if (!UCharacterProperty.isRuleWhiteSpace(c)) {

                break;

            }

            pos += UTF16.getCharCount(c);

        }

        return pos;

    }

    static final char DIGITS[] = {

        '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',

        'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',

        'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',

        'U', 'V', 'W', 'X', 'Y', 'Z'

    };

    /**

     * Append the digits of a positive integer to the given

     * <code>StringBuffer</code> in the given radix. This is

     * done recursively since it is easiest to generate the low-

     * order digit first, but it must be appended last.

     *

     * @param result is the <code>StringBuffer</code> to append to

     * @param n is the positive integer

     * @param radix is the radix, from 2 to 36 inclusive

     * @param minDigits is the minimum number of digits to append.

     */

    private static void recursiveAppendNumber(StringBuffer result, int n,

                                                int radix, int minDigits)

    {

        int digit = n % radix;

        if (n >= radix || minDigits > 1) {

            recursiveAppendNumber(result, n / radix, radix, minDigits - 1);

        }

        result.append(DIGITS[digit]);

    }

    /**

     * Append a number to the given StringBuffer in the given radix.

     * Standard digits '0'-'9' are used and letters 'A'-'Z' for

     * radices 11 through 36.

     * @param result the digits of the number are appended here

     * @param n the number to be converted to digits; may be negative.

     * If negative, a '-' is prepended to the digits.

     * @param radix a radix from 2 to 36 inclusive.

     * @param minDigits the minimum number of digits, not including

     * any '-', to produce.  Values less than 2 have no effect.  One

     * digit is always emitted regardless of this parameter.

     * @return a reference to result

     */

    public static StringBuffer appendNumber(StringBuffer result, int n,

                                             int radix, int minDigits)

        throws IllegalArgumentException

    {

        if (radix < 2 || radix > 36) {

            throw new IllegalArgumentException("Illegal radix " + radix);

        }

        int abs = n;

        if (n < 0) {

            abs = -n;

            result.append("-");

        }

        recursiveAppendNumber(result, abs, radix, minDigits);

        return result;

    }

    /**

     * Return true if the character is NOT printable ASCII.  The tab,

     * newline and linefeed characters are considered unprintable.

     */

    public static boolean isUnprintable(int c) {

        return !(c >= 0x20 && c <= 0x7E);

    }

    /**

     * above.  If the character is printable ASCII, then do nothing

     * and return FALSE.  Otherwise, append the escaped notation and

     * return TRUE.

     */

    public static boolean escapeUnprintable(StringBuffer result, int c) {

        if (isUnprintable(c)) {

            result.append('\\');

            if ((c & ~0xFFFF) != 0) {

                result.append('U');

                result.append(DIGITS[0xF&(c>>28)]);

                result.append(DIGITS[0xF&(c>>24)]);

                result.append(DIGITS[0xF&(c>>20)]);

                result.append(DIGITS[0xF&(c>>16)]);

            } else {

                result.append('u');

            }

            result.append(DIGITS[0xF&(c>>12)]);

            result.append(DIGITS[0xF&(c>>8)]);

            result.append(DIGITS[0xF&(c>>4)]);

            result.append(DIGITS[0xF&c]);

            return true;

        }

        return false;

    }

    /**

    * Similar to StringBuffer.getChars, version 1.3.

    * Since JDK 1.2 implements StringBuffer.getChars differently, this method

    * is here to provide consistent results.

    * To be removed after JDK 1.2 ceased to be the reference platform.

    * @param src source string buffer

    * @param srcBegin offset to the start of the src to retrieve from

    * @param srcEnd offset to the end of the src to retrieve from

    * @param dst char array to store the retrieved chars

    * @param dstBegin offset to the start of the destination char array to

    *                 store the retrieved chars

    */

    public static void getChars(StringBuffer src, int srcBegin, int srcEnd,

                                char dst[], int dstBegin)

    {

        if (srcBegin == srcEnd) {

            return;

        }

        src.getChars(srcBegin, srcEnd, dst, dstBegin);

    }

}