String.h

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#pragma once

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

#include <algorithm>
#include <ostream>

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

ONIXS_CONFLATEDUDP_NAMESPACE_BEGIN

/// Character type alias.
typedef char Char;

/// Provides efficient way of accessing 
/// text-based values without copying 
/// content of the text being referred. 
ONIXS_CONFLATEDUDP_LTWT_CLASS StrRef
{
    // Items being referenced.
    const Char* items_;

    // Number of chars being referenced.
    size_t size_;

public:
    /// STL-like iterator.
    typedef const Char* Iterator;

    /// Initializes the instance referring to nothing.
    StrRef()
        : items_(0)
        , 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(0, 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_);
    }
};

/// 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_CONFLATEDUDP_NAMESPACE_END