mundy::StringLiteral< StrSize > Struct Template Reference

Literal class type that wraps a constant expression string. More...

#include <StringLiteral.hpp>

Inheritance diagram for mundy::StringLiteral< StrSize >:

Public Member Functions
constexpr	StringLiteral ()
	Default constructor that initializes the string literal to an empty string.
constexpr	StringLiteral (const char(&str)[StrSize])
	Constructor that copies the string literal into the struct.
std::string	to_string () const
	Convert the string literal to a std::string.
template<size_t OtherStrSize>
constexpr StringLiteral< StrSize+OtherStrSize - 1 >	operator+ (const StringLiteral< OtherStrSize > &rhs) const
	Compile-time concatenation with another StringLiteral.
template<size_t OtherStrSize>
constexpr StringLiteral< StrSize+OtherStrSize - 1 >	operator+ (const char(&rhs)[OtherStrSize]) const
	Compile-time concatenation with a char array.

Public Attributes
char	value [StrSize]
	The string literal's content.

Static Public Attributes
static constexpr size_t	size = StrSize
	The string literal's size.

Detailed Description

template<size_t StrSize>
struct mundy::StringLiteral< StrSize >

The StringLiteral struct allows templates to accept constant strings, effectively turning them into compile-time constants. This can result in performance benefits as computations using these strings can be performed at compile time.

How It Works: The constexpr keyword is used to ensure that all computations involving StringLiteral are done at compile time. The StringLiteral struct takes in the string and its size as template parameters and stores them. The string can then be accessed with the value member, and the size with the size member.

Example Usage:

template <StringLiteral StrLit>
void Print() {
  // The size of the string is available as a constant expression.
  constexpr auto size = StrLit.size;
 
  // and so is the string's content.
  constexpr auto contents = StrLit.value;
 
  std::cout << "Size: " << size << ", Contents: " << contents << std::endl;
}
 
int main() {
  Print<make_string_literal("literal string")>();  // Prints "Size: 15, Contents: literal string"
}

Credit where credit is due: This design entirely originates from Kevin Hartman's Passing String Literals as Template Parameters in C++20 blog post: https://ctrpeach.io/posts/cpp20-string-literal-template-parameters/#:~:text=This%20would%20work%20by%20wrapping,e.g.%20char%5BN%5D%20).

Template Parameters

StrSize

The size of the string literal

Constructor & Destructor Documentation

StringLiteral() [1/2]

template<size_t StrSize>

mundy::StringLiteral< StrSize >::StringLiteral ( )

inlineconstexpr

StringLiteral() [2/2]

template<size_t StrSize>

mundy::StringLiteral< StrSize >::StringLiteral ( const char(&) str[StrSize] )

inlineexplicitconstexpr

Parameters

str	The string literal to copy

Member Function Documentation

to_string()

template<size_t StrSize>

std::string mundy::StringLiteral< StrSize >::to_string ( ) const

inline

operator+() [1/2]

template<size_t StrSize>

template<size_t OtherStrSize>

StringLiteral< StrSize+OtherStrSize - 1 > mundy::StringLiteral< StrSize >::operator+ ( const StringLiteral< OtherStrSize > & rhs ) const

inlineconstexpr

Parameters

rhs	The right-hand side of the concatenation

Returns

A new StringLiteral with the combined content of the two input StringLiterals

operator+() [2/2]

template<size_t StrSize>

template<size_t OtherStrSize>

StringLiteral< StrSize+OtherStrSize - 1 > mundy::StringLiteral< StrSize >::operator+ ( const char(&) rhs[OtherStrSize] ) const

inlineconstexpr

Parameters

rhs	The right-hand side of the concatenation

Returns

A new StringLiteral with the combined content of the input StringLiteral and char array

Member Data Documentation

value

template<size_t StrSize>

char mundy::StringLiteral< StrSize >::value[StrSize]

size

template<size_t StrSize>

size_t mundy::StringLiteral< StrSize >::size = StrSize

staticconstexpr