/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */


#ifndef MITREXSL_EXPRLEXER_H
#define MITREXSL_EXPRLEXER_H

#include "txCore.h"
#include "nsString.h"

/**
 * A Token class for the ExprLexer.
 *
 * This class was ported from XSL:P, an open source Java based 
 * XSLT processor, written by yours truly.
 */
class Token
{
public:

    /**
     * Token types
     */
    enum Type {
        //-- Trivial Tokens
        NULL_TOKEN = 1,
        LITERAL,
        NUMBER,
        CNAME,
        VAR_REFERENCE,
        PARENT_NODE,
        SELF_NODE,
        R_PAREN,
        R_BRACKET, // 9
        /**
         * start of tokens for 3.7, bullet 1
         * ExprLexer::nextIsOperatorToken bails if the tokens aren't
         * consecutive.
         */
        COMMA,
        AT_SIGN,
        L_PAREN,
        L_BRACKET,
        AXIS_IDENTIFIER,

        // These tokens include their following left parenthesis
        FUNCTION_NAME_AND_PAREN, // 15
        COMMENT_AND_PAREN,
        NODE_AND_PAREN,
        PROC_INST_AND_PAREN,
        TEXT_AND_PAREN,

        /**
         * operators
         */
        //-- boolean ops
        AND_OP, // 20
        OR_OP,

        //-- relational
        EQUAL_OP, // 22
        NOT_EQUAL_OP,
        LESS_THAN_OP,
        GREATER_THAN_OP,
        LESS_OR_EQUAL_OP,
        GREATER_OR_EQUAL_OP,
        //-- additive operators
        ADDITION_OP, // 28
        SUBTRACTION_OP,
        //-- multiplicative
        DIVIDE_OP, // 30
        MULTIPLY_OP,
        MODULUS_OP,
        //-- path operators
        PARENT_OP, // 33
        ANCESTOR_OP,
        UNION_OP,
        /**
         * end of tokens for 3.7, bullet 1 -/
         */
        //-- Special endtoken
        END // 36
    };


    /**
     * Constructors
     */
    typedef nsASingleFragmentString::const_char_iterator iterator;

    Token(iterator aStart, iterator aEnd, Type aType)
        : mStart(aStart),
          mEnd(aEnd),
          mType(aType),
          mNext(nullptr)
    {
    }
    Token(iterator aChar, Type aType)
        : mStart(aChar),
          mEnd(aChar + 1),
          mType(aType),
          mNext(nullptr)
    {
    }

    const nsDependentSubstring Value()
    {
        return Substring(mStart, mEnd);
    }

    iterator mStart, mEnd;
    Type mType;
    Token* mNext;
};

/**
 * A class for splitting an "Expr" String into tokens and
 * performing  basic Lexical Analysis.
 *
 * This class was ported from XSL:P, an open source Java based XSL processor
 */

class txExprLexer
{
public:

    txExprLexer();
    ~txExprLexer();

    /**
     * Parse the given string.
     * returns an error result if lexing failed.
     * The given string must outlive the use of the lexer, as the
     * generated Tokens point to Substrings of it.
     * mPosition points to the offending location in case of an error.
     */
    nsresult parse(const nsASingleFragmentString& aPattern);

    typedef nsASingleFragmentString::const_char_iterator iterator;
    iterator mPosition;

    /**
     * Functions for iterating over the TokenList
     */

    Token* nextToken();
    Token* peek()
    {
        NS_ASSERTION(mCurrentItem, "peek called uninitialized lexer");
        return mCurrentItem;
    }
    Token* peekAhead()
    {
        NS_ASSERTION(mCurrentItem, "peekAhead called on uninitialized lexer");
        // Don't peek past the end node
        return (mCurrentItem && mCurrentItem->mNext) ? mCurrentItem->mNext : mCurrentItem;
    }
    bool hasMoreTokens()
    {
        NS_ASSERTION(mCurrentItem, "HasMoreTokens called on uninitialized lexer");
        return (mCurrentItem && mCurrentItem->mType != Token::END);
    }

    /**
     * Trivial Tokens
     */
    //-- LF, changed to enum
    enum _TrivialTokens {
        D_QUOTE        = '\"',
        S_QUOTE        = '\'',
        L_PAREN        = '(',
        R_PAREN        = ')',
        L_BRACKET      = '[',
        R_BRACKET      = ']',
        L_ANGLE        = '<',
        R_ANGLE        = '>',
        COMMA          = ',',
        PERIOD         = '.',
        ASTERISK       = '*',
        FORWARD_SLASH  = '/',
        EQUAL          = '=',
        BANG           = '!',
        VERT_BAR       = '|',
        AT_SIGN        = '@',
        DOLLAR_SIGN    = '$',
        PLUS           = '+',
        HYPHEN         = '-',
        COLON          = ':',
        //-- whitespace tokens
        SPACE          = ' ',
        TX_TAB            = '\t',
        TX_CR             = '\n',
        TX_LF             = '\r'
    };

private:

    Token* mCurrentItem;
    Token* mFirstItem;
    Token* mLastItem;

    int mTokenCount;

    void addToken(Token* aToken);

    /**
     * Returns true if the following Token should be an operator.
     * This is a helper for the first bullet of [XPath 3.7]
     *  Lexical Structure
     */
    bool nextIsOperatorToken(Token* aToken);

    /**
     * Returns true if the given character represents a numeric letter (digit)
     * Implemented in ExprLexerChars.cpp
     */
    static bool isXPathDigit(char16_t ch)
    {
        return (ch >= '0' && ch <= '9');
    }
};

#endif