meta::parser::state Class Reference

Represents the current parser state of a shift-reduce parser. More...

#include <state.h>

Public Types
using	stack_type = util::persistent_stack< std::unique_ptr< node >>
	A persistent stack of partial parse trees.
using	queue_type = std::vector< std::unique_ptr< leaf_node >>
	The underlying queue type.

Public Member Functions
	state (const parse_tree &tree)
	Constructs a state from a parse tree. More...
	state (const sequence::sequence &sentence)
	Constructs a state from a POS-tagged sequence. More...
state	advance (const transition &trans) const
	Advances the current state by taking the given transition. More...
bool	legal (const transition &trans) const
	Checks if a transition is legal from a current state. More...
transition	emergency_transition () const
	Returns a transition used in situations where there is not a transition in the model satisfying the constraints given in the original paper so that the parser can at least make progress.
const node *	stack_item (size_t depth) const
const leaf_node *	queue_item (ssize_t depth) const
size_t	stack_size () const
size_t	queue_size () const
bool	finalized () const

Private Member Functions
	state (stack_type stack, std::shared_ptr< queue_type > queue, size_t q_idx, bool done)

Private Attributes
stack_type	stack_
	The stack of partial parse trees.
std::shared_ptr< queue_type >	queue_
	The queue of preterminals.
size_t	q_idx_
	The index of the front of the queue.
bool	done_
	Whether or not this state has finished parsing.

Detailed Description

Represents the current parser state of a shift-reduce parser.

Parser states consist of a stack of partial parse trees, a queue of pre-terminals, and whether or not the state is "finished".

The stack is represented using a persistent stack structure to ensure that updates to the parser state occur in O(1) time. The queue is static, so it can be represented as a vector + an index and updated in O(1) time.

Constructor & Destructor Documentation

meta::parser::state::state

(

const parse_tree &

tree

)

Constructs a state from a parse tree.

This is used to generate the starting state for parsing during training.

meta::parser::state::state

(

const sequence::sequence &

sentence

)

Constructs a state from a POS-tagged sequence.

This generates teh starting state for parsing during test time.

Member Function Documentation

state meta::parser::state::advance

(

const transition &

trans

)

const

Advances the current state by taking the given transition.

Parameters

trans

The transition to take to move the state forward

bool meta::parser::state::legal

(

const transition &

trans

)

const

Checks if a transition is legal from a current state.

See also

http://www.aclweb.org/anthology/W09-3825 Appendix

Parameters

trans

The transition to check

Returns

whether that transition is legal

const node * meta::parser::state::stack_item

(

size_t

depth

)

const

Parameters

depth

The depth to seek to in the stack

Returns

the node on the stack at the given depth

const leaf_node * meta::parser::state::queue_item

(

ssize_t

depth

)

const

Parameters

depth

The depth to seek to in the queue

Returns

the node on teh queue at the given depth

size_t meta::parser::state::stack_size

(

)

const

Returns

the number of partial parse trees on the stack.

size_t meta::parser::state::queue_size

(

)

const

Returns

the number of preterminals on the queue.

bool meta::parser::state::finalized

(

)

const

Returns

whether or not this state has finished parsing.

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

• /home/chase/projects/meta/include/parser/state.h
• /home/chase/projects/meta/src/parser/state.cpp