String.h

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#pragma once

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

#include <algorithm>
#include <ostream>

#include <OnixS/CME/MDH/Bootstrap.h>

ONIXS_CMEMDH_NAMESPACE_BEGIN

/// Character type alias.
typedef char Char;

/// Provides efficient way of accessing
/// text-based values without copying
/// content of the text being referred.
class ONIXS_CMEMDH_LTWT StrRef
{
public:
    /// STL-like iterator.
    typedef const Char* Iterator;

    /// Initializes the instance referring to nothing.
    StrRef()
        : items_(ONIXS_CMEMDH_NULLPTR)
        , size_(0)
    {
    }

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

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

    /// Indicates whether the referenced text is empty.
    bool empty() const
    {
        return (0 == size_);
    }

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

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

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

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

    /// Resets the reference to nothing.
    void reset()
    {
        reset(ONIXS_CMEMDH_NULLPTR, 0);
    }

    /// Updates the given instance
    /// to refer to the new text.
    void reset(const Char* chars, size_t size)
    {
        items_ = chars;
        size_ = size;
    }

    /// Provides per-item access.
    const Char& operator[](size_t index) const
    {
        return items_[index];
    }

    /// Provides bound-checked per-item access.
    const Char& at(size_t index) const
    {
        if (index < size_)
            return items_[index];

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

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

        return *this;
    }

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

        std::swap(size_, other.size_);
    }

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)
{
    const int result = memcmp(left.items(), right.items(), left.size() < right.size() ? left.size() : right.size());

    return (0 != result ? (0 > result) : (left.size() < right.size()));
}

/// 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_CMEMDH_NAMESPACE_END