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#ifndef _CFG_WFST_COMPOSER_H_
#define _CFG_WFST_COMPOSER_H_
#include <iostream>
#include <vector>
#include <utility>
#include "trule.h"
#include "wordid.h"
class CFG_WFSTComposerImpl;
class Hypergraph;
struct WFSTNode {
virtual ~WFSTNode();
// returns the next states reachable by consuming srcindex (which identifies a word)
// paired with the output string generated by taking that transition.
virtual std::vector<std::pair<const WFSTNode*,TRulePtr> > ExtendInput(unsigned srcindex) const = 0;
};
struct WFST {
virtual ~WFST();
virtual const WFSTNode* Final() const = 0;
virtual const WFSTNode* Initial() const = 0;
};
class CFG_WFSTComposer {
public:
~CFG_WFSTComposer();
explicit CFG_WFSTComposer(const WFST& wfst);
bool Compose(const Hypergraph& in_forest, Hypergraph* trg_forest);
// reads the grammar from a file. There must be a single top-level
// S -> X rule. Anything else is possible. Format is:
// [S] ||| [SS,1]
// [SS] ||| [NP,1] [VP,2] ||| Feature1=0.2 Feature2=-2.3
// [SS] ||| [VP,1] [NP,2] ||| Feature1=0.8
// [NP] ||| [DET,1] [N,2] ||| Feature3=2
// ...
bool Compose(std::istream* grammar_file, Hypergraph* trg_forest);
private:
CFG_WFSTComposerImpl* pimpl_;
};
#endif
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