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

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

/*

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

* Copyright (c) 2003-2011, International Business Machines

* Corporation and others.  All Rights Reserved.

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

* Author: Alan Liu

* Created: September 24 2003

* Since: ICU 2.8

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

*/

#include "ruleiter.h"

#include "unicode/parsepos.h"

#include "unicode/symtable.h"

#include "unicode/unistr.h"

#include "unicode/utf16.h"

#include "patternprops.h"

/* \U87654321 or \ud800\udc00 */

#define MAX_U_NOTATION_LEN 12

U_NAMESPACE_BEGIN

RuleCharacterIterator::RuleCharacterIterator(const UnicodeString& theText, const SymbolTable* theSym,

                      ParsePosition& thePos) :

    text(theText),

    pos(thePos),

    sym(theSym),

    buf(0),

    bufPos(0)

{}

UBool RuleCharacterIterator::atEnd() const {

    return buf == 0 && pos.getIndex() == text.length();

}

UChar32 RuleCharacterIterator::next(int32_t options, UBool& isEscaped, UErrorCode& ec) {

    if (U_FAILURE(ec)) return DONE;

    UChar32 c = DONE;

    isEscaped = FALSE;

    for (;;) {

        c = _current();

        _advance(U16_LENGTH(c));

        if (c == SymbolTable::SYMBOL_REF && buf == 0 &&

            (options & PARSE_VARIABLES) != 0 && sym != 0) {

            UnicodeString name = sym->parseReference(text, pos, text.length());

            // If name is empty there was an isolated SYMBOL_REF;

            // return it.  Caller must be prepared for this.

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

                break;

            }

            bufPos = 0;

            buf = sym->lookup(name);

            if (buf == 0) {

                ec = U_UNDEFINED_VARIABLE;

                return DONE;

            }

            // Handle empty variable value

            if (buf->length() == 0) {

                buf = 0;

            }

            continue;

        }

        if ((options & SKIP_WHITESPACE) != 0 && PatternProps::isWhiteSpace(c)) {

            continue;

        }

        if (c == 0x5C /*'\\'*/ && (options & PARSE_ESCAPES) != 0) {

            UnicodeString tempEscape;

            int32_t offset = 0;

            c = lookahead(tempEscape, MAX_U_NOTATION_LEN).unescapeAt(offset);

            jumpahead(offset);

            isEscaped = TRUE;

            if (c < 0) {

                ec = U_MALFORMED_UNICODE_ESCAPE;

                return DONE;

            }

        }

        break;

    }

    return c;

}

void RuleCharacterIterator::getPos(RuleCharacterIterator::Pos& p) const {

    p.buf = buf;

    p.pos = pos.getIndex();

    p.bufPos = bufPos;

}

void RuleCharacterIterator::setPos(const RuleCharacterIterator::Pos& p) {

    buf = p.buf;

    pos.setIndex(p.pos);

    bufPos = p.bufPos;

}

void RuleCharacterIterator::skipIgnored(int32_t options) {

    if ((options & SKIP_WHITESPACE) != 0) {

        for (;;) {

            UChar32 a = _current();

            if (!PatternProps::isWhiteSpace(a)) break;

            _advance(U16_LENGTH(a));

        }

    }

}

UnicodeString& RuleCharacterIterator::lookahead(UnicodeString& result, int32_t maxLookAhead) const {

    if (maxLookAhead < 0) {

        maxLookAhead = 0x7FFFFFFF;

    }

    if (buf != 0) {

        buf->extract(bufPos, maxLookAhead, result);

    } else {

        text.extract(pos.getIndex(), maxLookAhead, result);

    }

    return result;

}

void RuleCharacterIterator::jumpahead(int32_t count) {

    _advance(count);

}

/*

UnicodeString& RuleCharacterIterator::toString(UnicodeString& result) const {

    int32_t b = pos.getIndex();

    text.extract(0, b, result);

    return result.append((UChar) 0x7C).append(text, b, 0x7FFFFFFF); // Insert '|' at index

}

*/

UChar32 RuleCharacterIterator::_current() const {

    if (buf != 0) {

        return buf->char32At(bufPos);

    } else {

        int i = pos.getIndex();

        return (i < text.length()) ? text.char32At(i) : (UChar32)DONE;

    }

}

void RuleCharacterIterator::_advance(int32_t count) {

    if (buf != 0) {

        bufPos += count;

        if (bufPos == buf->length()) {

            buf = 0;

        }

    } else {

        pos.setIndex(pos.getIndex() + count);

        if (pos.getIndex() > text.length()) {

            pos.setIndex(text.length());

        }

    }

}

U_NAMESPACE_END

//eof