activemq-cpp/src/main/decaf/internal/util/HexStringParser.cpp

/*
 *  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.
 */

#include "HexStringParser.h"

#include <decaf/lang/Character.h>
#include <decaf/lang/Integer.h>
#include <decaf/lang/Long.h>
#include <decaf/lang/Double.h>
#include <decaf/lang/Float.h>
#include <decaf/util/StringTokenizer.h>
#include <decaf/lang/exceptions/NumberFormatException.h>

using namespace decaf;
using namespace decaf::util;
using namespace decaf::lang;
using namespace decaf::lang::exceptions;
using namespace decaf::internal;
using namespace decaf::internal::util;

////////////////////////////////////////////////////////////////////////////////
const std::string HexStringParser::HEX_SIGNIFICANT =
    "0[xX](\\p{XDigit}+\\.?|\\p{XDigit}*\\.\\p{XDigit}+)";
const std::string HexStringParser::BINARY_EXPONENT =
    "[pP]([+-]?\\d+)";
const std::string HexStringParser::FLOAT_TYPE_SUFFIX =
    "[fFdD]?";
const std::string HexStringParser::HEX_PATTERN =
    "[\\x00-\\x20]*([+-]?)" + HEX_SIGNIFICANT + BINARY_EXPONENT + FLOAT_TYPE_SUFFIX + "[\\x00-\\x20]*";

////////////////////////////////////////////////////////////////////////////////
HexStringParser::HexStringParser(int exponentWidth, int mantissaWidth) : EXPONENT_WIDTH(exponentWidth),
                                                                         MANTISSA_WIDTH(mantissaWidth),
                                                                         EXPONENT_BASE(0),
                                                                         MAX_EXPONENT(0),
                                                                         MIN_EXPONENT(),
                                                                         MANTISSA_MASK(),
                                                                         sign(0),
                                                                         exponent(0),
                                                                         mantissa(0),
                                                                         abandonedNumber() {
    this->EXPONENT_BASE = ~(-1 << (exponentWidth - 1));
    this->MAX_EXPONENT = ~(-1 << exponentWidth);
    this->MIN_EXPONENT = -(MANTISSA_WIDTH + 1);
    this->MANTISSA_MASK = ~(-1 << mantissaWidth);
}

////////////////////////////////////////////////////////////////////////////////
double HexStringParser::parseDouble(const std::string& hexString) {

    HexStringParser parser(DOUBLE_EXPONENT_WIDTH, DOUBLE_MANTISSA_WIDTH);
    long long result = parser.parse(hexString);
    return Double::longBitsToDouble(result);
}

////////////////////////////////////////////////////////////////////////////////
float HexStringParser::parseFloat(const std::string& hexString) {

    HexStringParser parser(FLOAT_EXPONENT_WIDTH, FLOAT_MANTISSA_WIDTH);
    int result = (int) parser.parse(hexString);
    return Float::intBitsToFloat(result);
}

////////////////////////////////////////////////////////////////////////////////
long long HexStringParser::parse(const std::string& hexString) {

    std::string* hexSegments = getSegmentsFromHexString(hexString);
    std::string signStr = hexSegments[0];
    std::string significantStr = hexSegments[1];
    std::string exponentStr = hexSegments[2];
    delete hexSegments;

    parseHexSign(signStr);
    parseExponent(exponentStr);
    parseMantissa(significantStr);

    sign <<= (MANTISSA_WIDTH + EXPONENT_WIDTH);
    exponent <<= MANTISSA_WIDTH;
    return sign | exponent | mantissa;
}

////////////////////////////////////////////////////////////////////////////////
std::string* HexStringParser::getSegmentsFromHexString(DECAF_UNUSED const std::string& hexString) {

//    apr_pool_t* thePool = NULL;
//    apr_pool_create( &thePool, NULL );
//    apr_strmatch_pattern* pattern =
//        apr_strmatch_precompile( thePool, HEX_PATTERN.c_str(), 0 );
//
//    std::vector<std::string> hexSegments;
//

// TODO
//    Matcher matcher = PATTERN.matcher(hexString);
//    if( !matcher.matches() ) {
//        throw NumberFormatException(
//            __FILE__, __LINE__,
//            "HexStringParser::getSegmentsFromHexString"
//            "Invalid hex string:", hexString.c_str() );
//    }
//
//    std::string* hexSegments = new std::string[3];
//    hexSegments[0] = matcher.group(1);
//    hexSegments[1] = matcher.group(2);
//    hexSegments[2] = matcher.group(3);
//
//    return hexSegments;

    return NULL;
}

////////////////////////////////////////////////////////////////////////////////
void HexStringParser::parseExponent(const std::string& exponentStr) {

    std::string newExponentStr = exponentStr;

    char leadingChar = newExponentStr.at(0);
    int expSign = (leadingChar == '-' ? -1 : 1);
    if (!Character::isDigit(leadingChar)) {
        newExponentStr = newExponentStr.substr(1, newExponentStr.size());
    }

    try {
        exponent = expSign * Long::parseLong(exponentStr);
        checkedAddExponent(EXPONENT_BASE);
    } catch (exceptions::NumberFormatException& e) {
        exponent = expSign * Long::MAX_VALUE;
    }
}

////////////////////////////////////////////////////////////////////////////////
void HexStringParser::parseMantissa(const std::string& significantStr) {

    StringTokenizer tokenizer(significantStr, "\\.");
    std::vector<std::string> strings;

    tokenizer.toArray(strings);

    std::string strIntegerPart = strings[0];
    std::string strDecimalPart = strings.size() > 1 ? strings[1] : "";

    std::string significand = getNormalizedSignificand(strIntegerPart, strDecimalPart);

    if (significand == "0") {
        setZero();
        return;
    }

    int offset = getOffset(strIntegerPart, strDecimalPart);
    checkedAddExponent(offset);

    if (exponent >= MAX_EXPONENT) {
        setInfinite();
        return;
    }

    if (exponent <= MIN_EXPONENT) {
        setZero();
        return;
    }

    if (significand.length() > MAX_SIGNIFICANT_LENGTH) {
        abandonedNumber = significand.substr(MAX_SIGNIFICANT_LENGTH);
        significand = significand.substr(0, MAX_SIGNIFICANT_LENGTH);
    }

    mantissa = Long::parseLong(significand, HEX_RADIX);

    if (exponent >= 1) {
        processNormalNumber();
    } else {
        processSubNormalNumber();
    }

}

////////////////////////////////////////////////////////////////////////////////
void HexStringParser::checkedAddExponent(long long offset) {

    long long result = exponent + offset;
    int expSign = Long::signum(exponent);

    if (expSign * Long::signum(offset) > 0 && expSign * Long::signum(result) < 0) {

        exponent = expSign * Long::MAX_VALUE;
    } else {
        exponent = result;
    }
}

////////////////////////////////////////////////////////////////////////////////
void HexStringParser::processNormalNumber() {
    int desiredWidth = MANTISSA_WIDTH + 2;
    fitMantissaInDesiredWidth(desiredWidth);
    round();
    mantissa = mantissa & MANTISSA_MASK;
}

////////////////////////////////////////////////////////////////////////////////
void HexStringParser::processSubNormalNumber() {
    int desiredWidth = MANTISSA_WIDTH + 1;
    desiredWidth += (int) exponent; //lends bit from mantissa to exponent
    exponent = 0;
    fitMantissaInDesiredWidth(desiredWidth);
    round();
    mantissa = mantissa & MANTISSA_MASK;
}

////////////////////////////////////////////////////////////////////////////////
void HexStringParser::fitMantissaInDesiredWidth(int desiredWidth) {
    int bitLength = countBitsLength(mantissa);
    if (bitLength > desiredWidth) {
        discardTrailingBits(bitLength - desiredWidth);
    } else {
        mantissa <<= (desiredWidth - bitLength);
    }
}

////////////////////////////////////////////////////////////////////////////////
void HexStringParser::discardTrailingBits(long long num) {
    long long mask = ~(-1L << num);
    abandonedNumber += (char) (mantissa & mask);
    mantissa >>= num;
}

////////////////////////////////////////////////////////////////////////////////
void HexStringParser::round() {

    std::string result = abandonedNumber;
    replaceAll(result, "0+", "");

    bool moreThanZero = (result.length() > 0 ? true : false);

    int lastDiscardedBit = (int) (mantissa & 1L);
    mantissa >>= 1;
    int tailBitInMantissa = (int) (mantissa & 1L);

    if (lastDiscardedBit == 1 && (moreThanZero || tailBitInMantissa == 1)) {

        int oldLength = countBitsLength(mantissa);
        mantissa += 1L;
        int newLength = countBitsLength(mantissa);

        //Rounds up to exponent when whole bits of mantissa are one-bits.
        if (oldLength >= MANTISSA_WIDTH && newLength > oldLength) {
            checkedAddExponent(1);
        }
    }
}

////////////////////////////////////////////////////////////////////////////////
std::string HexStringParser::getNormalizedSignificand(const std::string& strIntegerPart, const std::string& strDecimalPart) {

    std::string significand = strIntegerPart + strDecimalPart;

    replaceFirst(significand, "^0x", "");

    if (significand.length() == 0) {
        significand = "0";
    }
    return significand;
}

////////////////////////////////////////////////////////////////////////////////
int HexStringParser::getOffset(const std::string& strIntegerPart, const std::string& strDecimalPart) {

    std::string strIntegerPart2 = strIntegerPart;

    replaceFirst(strIntegerPart2, "^0+", "");

    //If the Integer part is a nonzero number.
    if (strIntegerPart.length() != 0) {
        std::string leadingNumber = strIntegerPart.substr(0, 1);
        return (int) ((strIntegerPart.length() - 1) * 4 + countBitsLength(Long::parseLong(leadingNumber, HEX_RADIX)) - 1);
    }

    //If the Integer part is a zero number.
    int i;
    for (i = 0; (std::size_t) i < strDecimalPart.length() && strDecimalPart.at(i) == '0'; i++) {
    };

    if ((std::size_t) i == strDecimalPart.length()) {
        return 0;
    }

    std::string leadingNumber = strDecimalPart.substr(i, i + 1);

    return (-i - 1) * 4 + countBitsLength(Long::parseLong(leadingNumber, HEX_RADIX)) - 1;
}

////////////////////////////////////////////////////////////////////////////////
int HexStringParser::countBitsLength(long long value) {
    int leadingZeros = Long::numberOfLeadingZeros(value);
    return Long::SIZE - leadingZeros;
}