1 files changed, 46 insertions, 0 deletions
diff --git a/gi/pf/cfg_wfst_composer.h b/gi/pf/cfg_wfst_composer.h
new file mode 100644
index 00000000..cf47f459
--- /dev/null
+++ b/gi/pf/cfg_wfst_composer.h
@@ -0,0 +1,46 @@
+#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