String.h

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// Copyright Onix Solutions Limited [OnixS]. All rights reserved.
//
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// protected by copyright law and international copyright treaties.
//
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// agreements granting a non-assignable, non-transferable and non-exclusive license 
// to use the software for it's own data processing purposes under the terms defined 
// in the Agreement.
//
// Except as otherwise granted within the terms of the Agreement, copying or 
// reproduction of any part of this source code or associated reference material 
// to any other location for further reproduction or redistribution, and any 
// amendments to this copyright notice, are expressly prohibited.
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#pragma once

#include <cstddef>
#include <cstring>
#include <string>
#include <stdexcept>

#include <algorithm>
#include <ostream>

#include <OnixS/eSpeed/MarketData/Itch/Bootstrap.h>
#include <OnixS/eSpeed/MarketData/Itch/Compiler.h>

ONIXS_ESPEED_ITCH_NAMESPACE_BEGIN

/// Character type alias.
typedef char Char;

/// Provides efficient way of accessing text-based FIX field values.
class StrRef
{
public:
    /// STL-like iterator.
    typedef const Char* Iterator;

    /// Initializes blank instance.
    ONIXS_ESPEED_ITCH_CONSTEXPR
    StrRef()
    ONIXS_ESPEED_ITCH_NOTHROW
        : items_(ONIXS_ESPEED_ITCH_NULLPTR)
        , size_(0)
    {
    }

    /// Full initialization.
    StrRef(
        const Char* chars,
        size_t size)
    ONIXS_ESPEED_ITCH_NOTHROW
        : items_(chars)
        , size_(size)
    {
    }

    /// Full initialization.
    template <size_t Size>
    explicit
    ONIXS_ESPEED_ITCH_CONSTEXPR
    StrRef(const char (&value)[Size])
    ONIXS_ESPEED_ITCH_NOTHROW
        : items_(value)
        , size_(Size - 1)
    {
    }

    /// Full initialization.
    explicit
    StrRef(
        const std::string& string)
    ONIXS_ESPEED_ITCH_NOTHROW
        : items_(string.c_str())
        , size_(string.size())
    {
    }

    /// Initializes as clone of other instance.
    /// Data referenced by clone is not copied.
    /// Instead both instances will refer to same
    /// text segment.
    StrRef(
        const StrRef& other)
    ONIXS_ESPEED_ITCH_NOTHROW
        : items_(other.items_)
        , size_(other.size_)
    {
    }

#if defined(ONIXS_ESPEED_ITCH_COMPILER_CXX_RVALUE_REFERENCES) && ONIXS_ESPEED_ITCH_COMPILER_CXX_RVALUE_REFERENCES

    ONIXS_ESPEED_ITCH_CONSTEXPR
    StrRef(
        StrRef&& other)
    ONIXS_ESPEED_ITCH_NOTHROW
        : items_(std::move(other.items_))
        , size_(std::move(other.size_))
    {
    }

    StrRef& operator= (StrRef&& other)
    ONIXS_ESPEED_ITCH_NOTHROW
    {
        if (this == &other)
            return *this;

        items_ = std::move(other.items_);
        size_ = std::move(other.size_);

        return *this;
    }

#endif

    /// Indicates whether array of zero length.
    bool empty() const
    ONIXS_ESPEED_ITCH_NOTHROW
    {
        return (0 == size_);
    }

    /// Read-only content.
    const Char* items() const
    ONIXS_ESPEED_ITCH_NOTHROW
    {
        return items_;
    }

    /// Number of chars.
    size_t size() const
    ONIXS_ESPEED_ITCH_NOTHROW
    {
        return size_;
    }

    /// STL-like begin().
    Iterator begin() const
    ONIXS_ESPEED_ITCH_NOTHROW
    {
        return items_;
    }

    /// STL-like end().
    Iterator end() const
    ONIXS_ESPEED_ITCH_NOTHROW
    {
        return (items_ + size_);
    }

    /// Resets reference to nothing.
    void reset()
    ONIXS_ESPEED_ITCH_NOTHROW
    {
        reset(ONIXS_ESPEED_ITCH_NULLPTR, 0);
    }

    /// Updates data being referenced.
    void
    reset(
        const Char* chars,
        size_t size)
    ONIXS_ESPEED_ITCH_NOTHROW
    {
        items_ = chars;
        size_ = size;
    }

    const Char&
    operator [](
        size_t index) const
    {
        return items_[index];
    }

    const Char&
    at(
        size_t index) const
    {
        if (index < size_)
            return items_[index];

        throw std::invalid_argument("index");
    }

    /// Reinitializes from another instance.
    StrRef&
    operator =(
        const StrRef& other)
    ONIXS_ESPEED_ITCH_NOTHROW
    {
        items_ = other.items_;
        size_ = other.size_;

        return *this;
    }

    /// Swaps content with other instance.
    void
    swap(
        StrRef& other)
    ONIXS_ESPEED_ITCH_NOTHROW
    {
        std::swap(items_, other.items_);
        std::swap(size_, other.size_);
    }

    // Get trimmed presentation of the current string
    StrRef trim() const
    ONIXS_ESPEED_ITCH_NOTHROW
    {
        size_t length = size();

        while(length > 0 && isspace(operator[](length - 1)))
            --length;

        return StrRef(items(), length);
    }

private:
    /// Items being referenced.
    const Char* items_;

    /// Number of chars being referenced.
    size_t size_;
};

/// Constructs StrRef instance over std::string content.
inline
    StrRef
    toStrRef(
        const std::string& str)
{
    return StrRef(str.data(), str.size());
}

/// Initializes instance from zero-terminated/C-like string.
inline
    StrRef
    toStrRef(
        const Char* cStr)
{
    return
        StrRef(
            cStr,
            cStr
            ? strlen(cStr)
            : 0
        );
}

/// Constructs std::string instance from StrRef one. 
inline
    std::string
    toStr(
        const StrRef& ref)
{
    return std::string(ref.items(), ref.size());
}

/// Appends text referenced by StrRef to given std::string instance. 
inline
    void
    toStr(
        std::string& str,
        const StrRef& ref)
{
    str.append(ref.items(), ref.size());
}

/// Constructs std::string from a character. 
inline
    std::string
    toStr(
        Char character)
{
    return std::string(1, character);
}

/// Appends character to given std::string instance. 
inline
    void
    toStr(
        std::string& str,
        Char character)
{
    str.append(1, character);
}

/// Appends one string another one. 
inline
    void
    toStr(
        std::string& str,
        const std::string& value)
{
    str.append(value);
}

/// Compares StrRef instance with another one.
inline
    bool
    operator ==(
        const StrRef& left,
        const StrRef& right)
{
    return (
        left.size() == right.size()
        &&
        0 == memcmp(
            left.items(), right.items(), left.size()));
}

/// Compares with another instance.
inline
    bool
    operator !=(
        const StrRef& left,
        const StrRef& right)
{
    return !(left == right);
}

/// Compares StrRef with std::string. 
inline
    bool
    operator ==(
        const StrRef& ref,
        const std::string& str)
{
    return ref == toStrRef(str);
}

/// Compares StrRef with std::string. 
inline
    bool
    operator !=(
        const StrRef& ref,
        const std::string& str)
{
    return ref != toStrRef(str);
}

/// Compares StrRef with std::string. 
inline
    bool
    operator ==(
        const std::string& str,
        const StrRef& ref)
{
    return ref == toStrRef(str);
}

/// Compares StrRef with std::string. 
inline
    bool
    operator !=(
        const std::string& str,
        const StrRef& ref)
{
    return ref != toStrRef(str);
}

/// Compares StrRef with zero-terminated/C-like string. 
inline
    bool
    operator ==(
        const StrRef& ref,
        const Char* str)
{
    return ref == toStrRef(str);
}

/// Compares StrRef with zero-terminated/C-like string. 
inline
    bool
    operator !=(
        const StrRef& ref,
        const Char* str)
{
    return ref != toStrRef(str);
}

/// Compares StrRef with zero-terminated/C-like string. 
inline
    bool
    operator ==(
        const Char* str,
        const StrRef& ref)
{
    return ref == toStrRef(str);
}

/// Compares StrRef with zero-terminated/C-like string. 
inline
    bool
    operator !=(
        const Char* str,
        const StrRef& ref)
{
    return ref != toStrRef(str);
}

/// Establishes order over string refs.
inline
    bool
    operator <(
        const StrRef& left,
        const StrRef& right)
{
    ptrdiff_t
        compareResult =
        memcmp(
            left.items(),
            right.items(),
            left.size() < right.size()
            ? left.size()
            : right.size());

    if (0 == compareResult)
    {
        compareResult =
            static_cast<ptrdiff_t>(
                left.size() - right.size());
    }

    return (0 > compareResult);
}

/// Establishes order over string refs.
inline
    bool
    operator >(
        const StrRef& left,
        const StrRef& right)
{
    return (right < left);
}

/// StrRef serialization operator.
inline
    std::ostream&
    operator <<(
        std::ostream& stream,
        const StrRef& text)
{
    stream.write(text.items(), text.size());

    return stream;
}

ONIXS_ESPEED_ITCH_NAMESPACE_END