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FileNode Class Reference
Public Types | Public Member Functions

FileNode Class Reference
[XML/YAML Persistence]

File Storage Node class. More...

#include <persistence.hpp>

Public Types

enum  Type {
  NONE = 0, INT = 1, REAL = 2, FLOAT = REAL,
  STR = 3, STRING = STR, REF = 4, SEQ = 5,
  MAP = 6 , FLOW = 8, USER = 16, EMPTY = 32,
  NAMED = 64
}
 

type of the file storage node

More...

Public Member Functions

CV_WRAP FileNode ()
 The constructors.
 FileNode (const CvFileStorage *fs, const CvFileNode *node)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
 FileNode (const FileNode &node)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
FileNode operator[] (const String &nodename) const
 Returns element of a mapping node or a sequence node.
CV_WRAP FileNode operator[] (const char *nodename) const
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
CV_WRAP FileNode operator[] (int i) const
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
CV_WRAP int type () const
 Returns type of the node.
CV_WRAP bool empty () const
 returns true if the node is empty
CV_WRAP bool isNone () const
 returns true if the node is a "none" object
CV_WRAP bool isSeq () const
 returns true if the node is a sequence
CV_WRAP bool isMap () const
 returns true if the node is a mapping
CV_WRAP bool isInt () const
 returns true if the node is an integer
CV_WRAP bool isReal () const
 returns true if the node is a floating-point number
CV_WRAP bool isString () const
 returns true if the node is a text string
CV_WRAP bool isNamed () const
 returns true if the node has a name
CV_WRAP String name () const
 returns the node name or an empty string if the node is nameless
CV_WRAP size_t size () const
 returns the number of elements in the node, if it is a sequence or mapping, or 1 otherwise.
 operator int () const
 returns the node content as an integer. If the node stores floating-point number, it is rounded.
 operator float () const
 returns the node content as float
 operator double () const
 returns the node content as double
 operator String () const
 returns the node content as text string
CvFileNode * operator* ()
 returns pointer to the underlying file node
const CvFileNode * operator* () const
 returns pointer to the underlying file node
FileNodeIterator begin () const
 returns iterator pointing to the first node element
FileNodeIterator end () const
 returns iterator pointing to the element following the last node element
void readRaw (const String &fmt, uchar *vec, size_t len) const
 Reads node elements to the buffer with the specified format.
void * readObj () const
 reads the registered object and returns pointer to it

Related Functions

(Note that these are not member functions.)


template<typename _Tp >
static void operator>> (const FileNode &n, _Tp &value)
 Reads data from a file storage.
template<typename _Tp >
static void operator>> (const FileNode &n, std::vector< _Tp > &vec)
 Reads data from a file storage.

Detailed Description

File Storage Node class.

The node is used to store each and every element of the file storage opened for reading. When XML/YAML file is read, it is first parsed and stored in the memory as a hierarchical collection of nodes. Each node can be a “leaf” that is contain a single number or a string, or be a collection of other nodes. There can be named collections (mappings) where each element has a name and it is accessed by a name, and ordered collections (sequences) where elements do not have names but rather accessed by index. Type of the file node can be determined using FileNode::type method.

Note that file nodes are only used for navigating file storages opened for reading. When a file storage is opened for writing, no data is stored in memory after it is written.

Definition at line 454 of file persistence.hpp.

Member Enumeration Documentation

enum Type

type of the file storage node

Enumerator:
NONE 

empty node

INT 

an integer

REAL 

floating-point number

FLOAT 

synonym or REAL

STR 

text string in UTF-8 encoding

STRING 

synonym for STR

REF 

integer of size size_t. Typically used for storing complex dynamic structures where some elements reference the others

SEQ 

sequence

MAP 

mapping

FLOW 

compact representation of a sequence or mapping. Used only by YAML writer

USER 

a registered object (e.g. a matrix)

EMPTY 

empty structure (sequence or mapping)

NAMED 

the node has a name (i.e. it is element of a mapping)

Definition at line 458 of file persistence.hpp.

Constructor & Destructor Documentation

CV_WRAP FileNode (  )

The constructors.

These constructors are used to create a default file node, construct it from obsolete structures or from the another file node.

FileNode ( const CvFileStorage *  fs,
const CvFileNode *  node 
)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters:
fsPointer to the obsolete file storage structure.
nodeFile node to be used as initialization for the created file node.
FileNode ( const FileNode &  node )

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters:
nodeFile node to be used as initialization for the created file node.

Member Function Documentation

FileNodeIterator begin (  ) const

returns iterator pointing to the first node element

CV_WRAP bool empty (  ) const

returns true if the node is empty

FileNodeIterator end (  ) const

returns iterator pointing to the element following the last node element

CV_WRAP bool isInt (  ) const

returns true if the node is an integer

CV_WRAP bool isMap (  ) const

returns true if the node is a mapping

CV_WRAP bool isNamed (  ) const

returns true if the node has a name

CV_WRAP bool isNone (  ) const

returns true if the node is a "none" object

CV_WRAP bool isReal (  ) const

returns true if the node is a floating-point number

CV_WRAP bool isSeq (  ) const

returns true if the node is a sequence

CV_WRAP bool isString (  ) const

returns true if the node is a text string

CV_WRAP String name (  ) const

returns the node name or an empty string if the node is nameless

operator double (  ) const

returns the node content as double

operator float (  ) const

returns the node content as float

operator int (  ) const

returns the node content as an integer. If the node stores floating-point number, it is rounded.

operator String (  ) const

returns the node content as text string

CvFileNode* operator* (  )

returns pointer to the underlying file node

const CvFileNode* operator* (  ) const

returns pointer to the underlying file node

CV_WRAP FileNode operator[] ( int  i ) const

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters:
iIndex of an element in the sequence node.
CV_WRAP FileNode operator[] ( const char *  nodename ) const

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters:
nodenameName of an element in the mapping node.
FileNode operator[] ( const String &  nodename ) const

Returns element of a mapping node or a sequence node.

Parameters:
nodenameName of an element in the mapping node.
Returns:
Returns the element with the given identifier.
void* readObj (  ) const

reads the registered object and returns pointer to it

void readRaw ( const String &  fmt,
uchar *  vec,
size_t  len 
) const

Reads node elements to the buffer with the specified format.

Usually it is more convenient to use operator `>>` instead of this method.

Parameters:
fmtSpecification of each array element. See format specification
vecPointer to the destination array.
lenNumber of elements to read. If it is greater than number of remaining elements then all of them will be read.
CV_WRAP size_t size (  ) const

returns the number of elements in the node, if it is a sequence or mapping, or 1 otherwise.

CV_WRAP int type (  ) const

Returns type of the node.

Returns:
Type of the node. See FileNode::Type

Friends And Related Function Documentation

static void operator>> ( const FileNode &  n,
_Tp &  value 
) [related]

Reads data from a file storage.

Definition at line 1119 of file persistence.hpp.

static void operator>> ( const FileNode &  n,
std::vector< _Tp > &  vec 
) [related]

Reads data from a file storage.

Definition at line 1127 of file persistence.hpp.

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