lal::io::treebank_reader Class Reference

A reader for a single treebank file. More...

#include <treebank_reader.hpp>

Public Member Functions
treebank_error	init (const std::string &file, const std::string &identifier="") noexcept
	Initialises the treebank reader.
bool	end () const noexcept
	Returns whether there is another tree to be processed.
void	next_tree () noexcept
	Retrieves the next tree in the file.
size_t	get_num_trees () const noexcept
	Returns the number of trees processed so far.
const std::string &	get_identifier () const noexcept
	Returns the identifier corresponding of the treebank.
const std::string &	get_treebank_filename () const noexcept
	Returns the name of the treebank file.
graphs::rooted_tree	get_tree () const noexcept
	Returns the current tree.
head_vector	get_head_vector () const noexcept
	Returns the current head vector.
bool	is_open () const noexcept
	Can the treebank be read?
void	set_normalise (bool v) noexcept
	Should trees be normalised?
void	set_calculate_size_subtrees (bool v) noexcept
	Should the size of the subtrees be calculated?
void	set_calculate_tree_type (bool v) noexcept
	Should the tree be classified into types?
void	set_identifier (const std::string &id) noexcept
	Set this treebank's identifier string.

Private Attributes
std::string	m_treebank_identifier = "none"
	Identifier for the treebank.
std::string	m_treebank_file = "none"
	Treebank's file name (with the full path).
std::ifstream	m_treebank
	Handler for main file reading.
size_t	m_num_trees = 0
	Number of trees in the treebank.
std::string	m_file_line
	Current line.
head_vector	m_current_head_vector
	Current head vector.
bool	m_normalise_tree = true
	Normalise the current tree.
bool	m_calculate_size_subtrees = true
	Calculate the size of the subtrees of the generated rooted tree.
bool	m_calculate_tree_type = true
	Calculate the type of tree of the generated tree.
bool	m_no_more_trees = false
	Have all trees in the file been consumed?

Detailed Description

A reader for a single treebank file.

This class, the objects of which will be referred to as the "readers", offers a simple interface for iterating over the trees in a single treebank file, henceforth referred to as the treebank. Each tree is formatted as a list of whole, positive numbers (including zero), each representing a node of the tree. The number 0 denotes the root of the tree, and a number at a certain position indicates its parent node. For example, when number 4 is at position 9 it means that node 9 has parent node 4. Therefore, if number 0 is at position 1 it means that node 1 is the root of the tree. A complete example of such a tree's representation is the following

  0 3 4 1 6 3

which should be interpreted as

(a) predecessor:       0 3 4 1 6 3
(b) node of the tree:  1 2 3 4 5 6

Note that lines like these are not valid:

(1) 0 2 2 2 2 2
(2) 2 0 0

Line (1) is not valid due to a self-reference in the second position, and (2) not being valid due to containing two '0' (i.e., two roots).

In order to use it, this class has to be first initialized with the treebank file and, optionally, a self-descriptive string, i.e., something that identifies the treebank (e.g., an ISO code of a language). Once initialised, the first tree can be retrievend with get_tree. The other trees can be iterated over by calling next_tree. This function can only be called as long as end returns false.

If an object of this class was returned by the class treebank_collection_reader, then methods get_treebank_filename and get_identifier might prove useful for debugging since they return, respectively, the full name (path included) of the treebank and an identifier string.

An example of usage of this class is given in the following piece of code.

lal::io::treebank_reader tbread;
// it is advisable to check for errors
const auto err = tbread.init(main_file);
while (not tbread.end()) {
    const lal::graphs::rooted_tree t = tbread.get_tree();
    // process tree 't'
    // ....
    tbread.next_tree();
}

Member Function Documentation

get_num_trees()

size_t lal::io::treebank_reader::get_num_trees ( ) const

inlinenoexcept

Returns the number of trees processed so far.

When method end returns 'true', this method returns the exact amount of trees in the treebank.

init()

treebank_error lal::io::treebank_reader::init ( const std::string & file, const std::string & identifier = "" )

noexcept

Initialises the treebank reader.

Parameters

file	Treebank file.
identifier	Identifier string for the treebank.

Returns

The type of the error, if any. The list of errors that this method can return is:

• lal::io::treebank_error_type::treebank_file_could_not_be_opened

Postcondition

The amount of trees processed, m_num_trees, is always set to 0.

is_open()

bool lal::io::treebank_reader::is_open ( ) const

inlinenoexcept

Can the treebank be read?

If the init method returned an error different from lal::io::treebank_error_type::no_error then this returns false.

Returns

Whether the treebank is readable or not.

next_tree()

void lal::io::treebank_reader::next_tree ( )

noexcept

Retrieves the next tree in the file.

Postcondition

Increments the amount of trees found.

set_calculate_size_subtrees()

void lal::io::treebank_reader::set_calculate_size_subtrees ( bool v )

inlinenoexcept

Should the size of the subtrees be calculated?

Parameters

v	Boolean value.

set_calculate_tree_type()

void lal::io::treebank_reader::set_calculate_tree_type ( bool v )

inlinenoexcept

Should the tree be classified into types?

See lal::graphs::tree_type for details on the classification.

Parameters

v	Boolean value.

set_identifier()

void lal::io::treebank_reader::set_identifier ( const std::string & id )

inlinenoexcept

Set this treebank's identifier string.

This method overrides the contents of m_treebank_identifier. This method is most useful when, after initialising a treebank reader, the identifier string is to be changed in some way.

Parameters

id	Identifier string.

set_normalise()

void lal::io::treebank_reader::set_normalise ( bool v )

inlinenoexcept

Should trees be normalised?

Parameters

v	Boolean value.

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The documentation for this class was generated from the following file:

• lal/io/treebank_reader.hpp