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GenericStringRef< CharType > Struct Template Reference
Public Types | Public Member Functions | Data Fields | Related Functions

GenericStringRef< CharType > Struct Template Reference

Reference to a constant string (not taking a copy) More...

#include <document.h>

Public Types

typedef CharType Ch
 character type of the string

Public Member Functions

template<SizeType N>
 GenericStringRef (const CharType(&str)[N]) RAPIDJSON_NOEXCEPT
 Create string reference from const character array.
 GenericStringRef (const CharType *str)
 Explicitly create string reference from const character pointer.
 GenericStringRef (const CharType *str, SizeType len)
 Create constant string reference from pointer and length.
 operator const Ch * () const
 implicit conversion to plain CharType pointer

Data Fields

const Ch *const s
 plain CharType pointer
const SizeType length
 length of the string (excluding the trailing NULL terminator)

Related Functions

(Note that these are not member functions.)


template<typename CharType >
GenericStringRef< CharType > StringRef (const CharType *str)
 Mark a character pointer as constant string.
template<typename CharType >
GenericStringRef< CharType > StringRef (const CharType *str, size_t length)
 Mark a character pointer as constant string.
template<typename CharType >
GenericStringRef< CharType > StringRef (const std::basic_string< CharType > &str)
 Mark a string object as constant string.

Detailed Description

template<typename CharType>
struct GenericStringRef< CharType >

Reference to a constant string (not taking a copy)

Template Parameters:
CharTypecharacter type of the string

This helper class is used to automatically infer constant string references for string literals, especially from const (!) character arrays.

The main use is for creating JSON string values without copying the source string via an Allocator. This requires that the referenced string pointers have a sufficient lifetime, which exceeds the lifetime of the associated GenericValue.

Example 

    Value v("foo");   // ok, no need to copy & calculate length
    const char foo[] = "foo";
    v.SetString(foo); // ok

    const char* bar = foo;
    // Value x(bar); // not ok, can't rely on bar's lifetime
    Value x(StringRef(bar)); // lifetime explicitly guaranteed by user
    Value y(StringRef(bar, 3));  // ok, explicitly pass length
See also:
StringRef, GenericValue::SetString

Definition at line 249 of file document.h.

Member Typedef Documentation

typedef CharType Ch

character type of the string

Definition at line 250 of file document.h.

Constructor & Destructor Documentation

GenericStringRef ( const CharType(&)  str[N] )

Create string reference from const character array.

This constructor implicitly creates a constant string reference from a const character array. It has better performance than StringRef(const CharType*) by inferring the string length from the array length, and also supports strings containing null characters.

Template Parameters:
Nlength of the string, automatically inferred
Parameters:
strConstant character array, lifetime assumed to be longer than the use of the string in e.g. a GenericValue
Postcondition:
s == str
Note:
Constant complexity.
There is a hidden, private overload to disallow references to non-const character arrays to be created via this constructor. By this, e.g. function-scope arrays used to be filled via snprintf are excluded from consideration. In such cases, the referenced string should be copied to the GenericValue instead.

Definition at line 278 of file document.h.

GenericStringRef ( const CharType *  str ) [explicit]

Explicitly create string reference from const character pointer.

This constructor can be used to explicitly create a reference to a constant string pointer.

See also:
StringRef(const CharType*)
Parameters:
strConstant character pointer, lifetime assumed to be longer than the use of the string in e.g. a GenericValue
Postcondition:
s == str
Note:
There is a hidden, private overload to disallow references to non-const character arrays to be created via this constructor. By this, e.g. function-scope arrays used to be filled via snprintf are excluded from consideration. In such cases, the referenced string should be copied to the GenericValue instead.

Definition at line 302 of file document.h.

GenericStringRef ( const CharType *  str,
SizeType  len 
)

Create constant string reference from pointer and length.

Parameters:
strconstant string, lifetime assumed to be longer than the use of the string in e.g. a GenericValue
lenlength of the string, excluding the trailing NULL terminator
Postcondition:
s == str && length == len
Note:
Constant complexity.

Definition at line 314 of file document.h.

Member Function Documentation

operator const Ch * (  ) const

implicit conversion to plain CharType pointer

Definition at line 320 of file document.h.

Friends And Related Function Documentation

GenericStringRef< CharType > StringRef ( const CharType *  str ) [related]

Mark a character pointer as constant string.

Mark a plain character pointer as a "string literal". This function can be used to avoid copying a character string to be referenced as a value in a JSON GenericValue object, if the string's lifetime is known to be valid long enough.

Template Parameters:
CharTypeCharacter type of the string
Parameters:
strConstant string, lifetime assumed to be longer than the use of the string in e.g. a GenericValue
Returns:
GenericStringRef string reference object
See also:
GenericValue::GenericValue(StringRefType), GenericValue::operator=(StringRefType), GenericValue::SetString(StringRefType), GenericValue::PushBack(StringRefType, Allocator&), GenericValue::AddMember

Definition at line 346 of file document.h.

GenericStringRef< CharType > StringRef ( const std::basic_string< CharType > &  str ) [related]

Mark a string object as constant string.

Mark a string object (e.g. std::string) as a "string literal". This function can be used to avoid copying a string to be referenced as a value in a JSON GenericValue object, if the string's lifetime is known to be valid long enough.

Template Parameters:
CharTypecharacter type of the string
Parameters:
strConstant string, lifetime assumed to be longer than the use of the string in e.g. a GenericValue
Returns:
GenericStringRef string reference object
Note:
Requires the definition of the preprocessor symbol RAPIDJSON_HAS_STDSTRING.

Definition at line 384 of file document.h.

GenericStringRef< CharType > StringRef ( const CharType *  str,
size_t  length 
) [related]

Mark a character pointer as constant string.

Mark a plain character pointer as a "string literal". This function can be used to avoid copying a character string to be referenced as a value in a JSON GenericValue object, if the string's lifetime is known to be valid long enough.

This version has better performance with supplied length, and also supports string containing null characters.

Template Parameters:
CharTypecharacter type of the string
Parameters:
strConstant string, lifetime assumed to be longer than the use of the string in e.g. a GenericValue
lengthThe length of source string.
Returns:
GenericStringRef string reference object

Definition at line 366 of file document.h.

Field Documentation

const SizeType length

length of the string (excluding the trailing NULL terminator)

Definition at line 323 of file document.h.

const Ch* const s

plain CharType pointer

Definition at line 322 of file document.h.

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