// © 2016 and later: Unicode, Inc. and others.

// License & terms of use: http://www.unicode.org/copyright.html

/*

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

*   Copyright (c) 2001-2016, International Business Machines

*   Corporation and others.  All Rights Reserved.

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

*   Date        Name        Description

*   11/19/2001  aliu        Creation.

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

*/

#include "unicode/uchar.h"

#include "unicode/utf16.h"

#include "patternprops.h"

#include "util.h"

U_NAMESPACE_BEGIN

/**

 * Parse an integer at pos, either of the form \d+ or of the form

 * 0x[0-9A-Fa-f]+ or 0[0-7]+, that is, in standard decimal, hex,

 * or octal format.

 * @param pos INPUT-OUTPUT parameter.  On input, the first

 * character to parse.  On output, the character after the last

 * parsed character.

 */

int32_t ICU_Utility::parseInteger(const UnicodeString& rule, int32_t& pos, int32_t limit) {

    int32_t count = 0;

    int32_t value = 0;

    int32_t p = pos;

    int8_t radix = 10;

    if (p < limit && rule.charAt(p) == 48 /*0*/) {

        if (p+1 < limit && (rule.charAt(p+1) == 0x78 /*x*/ || rule.charAt(p+1) == 0x58 /*X*/)) {

            p += 2;

            radix = 16;

        }

        else {

            p++;

            count = 1;

            radix = 8;

        }

    }

    while (p < limit) {

        int32_t d = u_digit(rule.charAt(p++), radix);

        if (d < 0) {

            --p;

            break;

        }

        ++count;

        int32_t v = (value * radix) + d;

        if (v <= value) {

            // If there are too many input digits, at some point

            // the value will go negative, e.g., if we have seen

            // "0x8000000" already and there is another '0', when

            // we parse the next 0 the value will go negative.

            return 0;

        }

        value = v;

    }

    if (count > 0) {

        pos = p;

    }

    return value;

}

/**

 * Parse a pattern string starting at offset pos.  Keywords are

 * matched case-insensitively.  Spaces may be skipped and may be

 * optional or required.  Integer values may be parsed, and if

 * they are, they will be returned in the given array.  If

 * successful, the offset of the next non-space character is

 * returned.  On failure, -1 is returned.

 * @param pattern must only contain lowercase characters, which

 * will match their uppercase equivalents as well.  A space

 * character matches one or more required spaces.  A '~' character

 * matches zero or more optional spaces.  A '#' character matches

 * an integer and stores it in parsedInts, which the caller must

 * ensure has enough capacity.

 * @param parsedInts array to receive parsed integers.  Caller

 * must ensure that parsedInts.length is >= the number of '#'

 * signs in 'pattern'.

 * @return the position after the last character parsed, or -1 if

 * the parse failed

 */

int32_t ICU_Utility::parsePattern(const UnicodeString& rule, int32_t pos, int32_t limit,

                              const UnicodeString& pattern, int32_t* parsedInts) {

    // TODO Update this to handle surrogates

    int32_t p;

    int32_t intCount = 0; // number of integers parsed

    for (int32_t i=0; i<pattern.length(); ++i) {

        UChar cpat = pattern.charAt(i);

        UChar c;

        switch (cpat) {

        case 32 /*' '*/:

            if (pos >= limit) {

                return -1;

            }

            c = rule.charAt(pos++);

            if (!PatternProps::isWhiteSpace(c)) {

                return -1;

            }

            // FALL THROUGH to skipWhitespace

            U_FALLTHROUGH;

        case 126 /*'~'*/:

            pos = skipWhitespace(rule, pos);

            break;

        case 35 /*'#'*/:

            p = pos;

            parsedInts[intCount++] = parseInteger(rule, p, limit);

            if (p == pos) {

                // Syntax error; failed to parse integer

                return -1;

            }

            pos = p;

            break;

        default:

            if (pos >= limit) {

                return -1;

            }

            c = (UChar) u_tolower(rule.charAt(pos++));

            if (c != cpat) {

                return -1;

            }

            break;

        }

    }

    return pos;

}

/**

 * Parse a Unicode identifier from the given string at the given

 * position.  Return the identifier, or an empty string if there

 * is no identifier.

 * @param str the string to parse

 * @param pos INPUT-OUPUT parameter.  On INPUT, pos is the

 * first character to examine.  It must be less than str.length(),

 * and it must not point to a whitespace character.  That is, must

 * have pos < str.length().  On

 * OUTPUT, the position after the last parsed character.

 * @return the Unicode identifier, or an empty string if there is

 * no valid identifier at pos.

 */

UnicodeString ICU_Utility::parseUnicodeIdentifier(const UnicodeString& str, int32_t& pos) {

    // assert(pos < str.length());

    UnicodeString buf;

    int p = pos;

    while (p < str.length()) {

        UChar32 ch = str.char32At(p);

        if (buf.length() == 0) {

            if (u_isIDStart(ch)) {

                buf.append(ch);

            } else {

                buf.truncate(0);

                return buf;

            }

        } else {

            if (u_isIDPart(ch)) {

                buf.append(ch);

            } else {

                break;

            }

        }

        p += U16_LENGTH(ch);

    }

    pos = p;

    return buf;

}

/**

 * Parse an unsigned 31-bit integer at the given offset.  Use

 * UCharacter.digit() to parse individual characters into digits.

 * @param text the text to be parsed

 * @param pos INPUT-OUTPUT parameter.  On entry, pos[0] is the

 * offset within text at which to start parsing; it should point

 * to a valid digit.  On exit, pos[0] is the offset after the last

 * parsed character.  If the parse failed, it will be unchanged on

 * exit.  Must be >= 0 on entry.

 * @param radix the radix in which to parse; must be >= 2 and <=

 * 36.

 * @return a non-negative parsed number, or -1 upon parse failure.

 * Parse fails if there are no digits, that is, if pos[0] does not

 * point to a valid digit on entry, or if the number to be parsed

 * does not fit into a 31-bit unsigned integer.

 */

int32_t ICU_Utility::parseNumber(const UnicodeString& text,

                                 int32_t& pos, int8_t radix) {

    // assert(pos[0] >= 0);

    // assert(radix >= 2);

    // assert(radix <= 36);

    int32_t n = 0;

    int32_t p = pos;

    while (p < text.length()) {

        UChar32 ch = text.char32At(p);

        int32_t d = u_digit(ch, radix);

        if (d < 0) {

            break;

        }

        n = radix*n + d;

        // ASSUME that when a 32-bit integer overflows it becomes

        // negative.  E.g., 214748364 * 10 + 8 => negative value.

        if (n < 0) {

            return -1;

        }

        ++p;

    }

    if (p == pos) {

        return -1;

    }

    pos = p;

    return n;

}

U_NAMESPACE_END