parse.hpp

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// Copyright 2010 Complete Genomics, Inc.
//
// Licensed 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.

#ifndef CGATOOLS_UTIL_PARSE_HPP_
#define CGATOOLS_UTIL_PARSE_HPP_ 1


#include "cgatools/core.hpp"
#include "cgatools/util/Exception.hpp"
#include <string>
#include <boost/static_assert.hpp>

namespace cgatools { namespace util {

    template <typename Value, bool IsSigned>
    struct ValueParser
    {
        static Value parse(const char* first, const char* last)
        {
            // You need to use one of the specializations of this
            // class. This assertion should fail whenever this class is
            // instantiated.
            BOOST_STATIC_ASSERT(0 == sizeof(Value));
        }
    };

    template <typename Value>
    struct ValueParser<Value, true>
    {
        static Value parse(const char* first, const char* last)
        {
            if (first == last)
                throw Exception("failed to parse int: empty string");

            bool neg = '-' == *first;

            const char* current = first;
            if (neg)
                ++current;

            if (current == last)
                throw Exception("failed to parse int: empty string");

            Value val(0);
            Value maxVal = std::numeric_limits<Value>::max() / 10;
            for(; current<last; current++)
            {
                if (*current < '0' || *current > '9')
                    throw Exception("failed to parse int: "+std::string(first, last));
                Value digit = *current - '0';
                if (val >= maxVal)
                {
                    Value maxDigit = std::numeric_limits<Value>::max() % 10;
                    if (neg && current+1 == last)
                        maxDigit++;
                    if (val > maxVal || digit > maxDigit)
                        throw Exception("failed to parse int: overflow: "+std::string(first, last));
                }
                val = val*10 + digit;
            }
            if (neg)
                val = -val;
            return val;
        }
    };

    template <typename Value>
    struct ValueParser<Value, false>
    {
        static Value parse(const char* first, const char* last)
        {
            if (first == last)
                throw Exception("failed to parse int: empty string");

            Value val(0);
            Value maxVal = std::numeric_limits<Value>::max() / 10;
            for(const char* current=first; current<last; current++)
            {
                if (*current < '0' || *current > '9')
                    throw Exception("failed to parse int: "+std::string(first, last));
                Value digit = *current - '0';
                if (val >= maxVal)
                {
                    Value maxDigit = std::numeric_limits<Value>::max() % 10;
                    if (val > maxVal || digit > maxDigit)
                        throw Exception("failed to parse int: overflow: "+std::string(first, last));
                }
                val = val*10 + digit;
            }
            return val;
        }
    };

    float  parseFloat (const char* first, const char* last);
    double parseDouble(const char* first, const char* last);

    template <>
    struct ValueParser<float, true>
    {
        static float parse(const char* first, const char* last)
        {
            return parseFloat(first, last);
        }
    };

    template <>
    struct ValueParser<double, true>
    {
        static double parse(const char* first, const char* last)
        {
            return parseDouble(first, last);
        }
    };

    template <typename Value>
    Value parseValue(const char* first, const char* last)
    {
        return ValueParser<Value, std::numeric_limits<Value>::is_signed>::parse(first, last);
    }

    template <typename Value> Value parseValue(const char* str)
    {
        const char* strEnd = str + std::strlen(str);
        return parseValue<Value>(str, strEnd);
    }

    template <typename Value> Value parseValue(const std::string& str)
    {
        return parseValue<Value>(str.c_str(), str.c_str()+str.length());
    }

} } // cgatools::util

#endif // CGATOOLS_UTIL_PARSE_HPP_

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