devhelpers.md

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devhelpers

devhelper functions to_tml_facts, to_tml_rules and to_dot can convert a parsed forest into various formats.

These functions shouldn't be necessary for your parser's production build but they can be helpful when debugging your implementation of a language parser, since it provides the parsed forest in a human readable forms or in a form which can be processed.

devhelper functions are available only on Debug target when compiling the parser library.

functions

to_dot(...);

template <typename C, typename T = C>
bool to_dot(std::ostream& os,
	const typename parser<C, T>::pforest& f,
	const std::string& inputstr,
	const std::string& grammar_text);

template <typename C, typename T = C, typename P = parser<C, T>::pnode_graph>
bool to_dot(std::ostream& os,
	P& g,
	const std::string& inputstr,
	const std::string& grammar_text);

Takes a forest f (or a graph g) and produces a DOT data streamed into os.

inputstr is meant for an input text and grammar_text is meant for a grammar text. Both texts are added into the DOT data but they can be shortened or customized.

DOT files can be used by dot utility to generate other formats for example for a graphical visualization (PNG, SVG...).

to_tml_facts(...);

template <typename C, typename T = C>
bool to_tml_facts(std::ostream& os,
	const typename parser<C, T>::pforest& f);

Takes a forest f and produces all its nodes and edges as facts in TML to ostream os.

Nodes and edges facts are provided in relations node and edge with following attributes:

node(node_id literal input_from_position input_to_position).
edge(nodeA_id nodeB_id).

Example for a grammar start => 'H' 'i'. and an input text "Hi":

node(0 start 0 2).
node(1 'H' 0 1).
node(2 'i' 1 2).
edge(0 1).
edge(0 2).

to_tml_rules(...);

template <typename C, typename T = C>
bool to_tml_rules(std::ostream& os, const typename parser<C, T>::pforest& f);

template <typename C, typename T = C, typename P = parser<C, T>::pnode_graph>
bool to_tml_rules(std::ostream& os, P& g);

Takes a forest f (or a graph g) and produces its data as TML. Each node of the forest is either printed as a fact if it is a terminal or a rule if it is a non-terminal. Body of such a rule contains children nodes. All produced relations have two attributes: starting and ending positions of a literal in the input.

Example of a produced data when using grammar start => hi | hello. hi => "hi". hello => "hello". and parsing string "hi":

start(0 2) :- hi(0 2).
hi(0 2) :- 'h'(0 1), 'i'(1 2).
'h'(0 1).
'i'(1 2).

to_tml_rule(...);

template<typename C, typename T = C>
std::string to_tml_rule(const typename parser<C, T>::pnode& nd);

Produces a TML statement for a given forest or graph node nd as a TML fact or a TML rule. This method is used by to_tml_rules(...).