cleanup, document and export the completion API

1 files changed, 24 insertions, 17 deletions

diff --git a/src-3.0/PGF/Parsing/FCFG/Incremental.hs b/src-3.0/PGF/Parsing/FCFG/Incremental.hs
index f88af3d35..99387890c 100644
--- a/src-3.0/PGF/Parsing/FCFG/Incremental.hs
+++ b/src-3.0/PGF/Parsing/FCFG/Incremental.hs
@@ -1,6 +1,6 @@
 {-# LANGUAGE BangPatterns #-}

 module PGF.Parsing.FCFG.Incremental

-          ( State

+          ( ParseState

           , initState

           , nextState

           , getCompletions

@@ -10,7 +10,7 @@ module PGF.Parsing.FCFG.Incremental
 

 import Data.Array

 import Data.Array.Base (unsafeAt)

-import Data.List (isPrefixOf)

+import Data.List (isPrefixOf, foldl')

 import Data.Maybe (fromMaybe)

 import qualified Data.Map as Map

 import qualified Data.IntMap as IntMap

@@ -26,12 +26,9 @@ import PGF.Parsing.FCFG.Utilities
 import Debug.Trace

 

 parse :: ParserInfo -> CId -> [FToken] -> [Exp]

-parse pinfo start toks = go (initState pinfo start) toks

-  where

-    go st []     = extractExps pinfo start st

-    go st (t:ts) = go (nextState pinfo t st) ts

+parse pinfo start toks = extractExps (foldl' nextState (initState pinfo start) toks) start

 

-initState :: ParserInfo -> CId -> State

+initState :: ParserInfo -> CId -> ParseState

 initState pinfo start = 

   let items = do

         c <- Map.findWithDefault [] start (startupCats pinfo)

@@ -46,39 +43,47 @@ initState pinfo start =
                   Just ((fid,_), _) -> fid+1

                   Nothing           -> 0

 

-  in State (Chart MM.empty [] Map.empty forest max_fid 0)

+  in State pinfo

+           (Chart MM.empty [] Map.empty forest max_fid 0)

            (Set.fromList items)

 

-nextState :: ParserInfo -> FToken -> State -> State

-nextState pinfo t (State chart items) =

+-- | From the current state and the next token

+-- 'nextState' computes a new state where the token

+-- is consumed and the current position shifted by one.

+nextState :: ParseState -> String -> ParseState

+nextState (State pinfo chart items) t =

   let (items1,chart1) = process add (allRules pinfo) (Set.toList items) (Set.empty,chart)

       chart2 = chart1{ active =MM.empty

                      , actives=active chart1 : actives chart1

                      , passive=Map.empty

                      , offset =offset chart1+1

                      }

-  in State chart2 items1

+  in State pinfo chart2 items1

   where

     add tok item set

       | tok == t  = Set.insert item set

       | otherwise = set

 

-getCompletions :: ParserInfo -> FToken -> State -> Map.Map FToken State

-getCompletions pinfo w (State chart items) =

+-- | If the next token is not known but only its prefix (possible empty prefix)

+-- then the 'getCompletions' function can be used to calculate the possible

+-- next words and the consequent states. This is used for word completions in

+-- the GF interpreter.

+getCompletions :: ParseState -> String -> Map.Map String ParseState

+getCompletions (State pinfo chart items) w =

   let (map',chart1) = process add (allRules pinfo) (Set.toList items) (MM.empty,chart)

       chart2 = chart1{ active =MM.empty

                      , actives=active chart1 : actives chart1

                      , passive=Map.empty

                      , offset =offset chart1+1

                      }

-  in fmap (State chart2) map'

+  in fmap (State pinfo chart2) map'

   where

     add tok item map

       | isPrefixOf w tok = fromMaybe map (MM.insert' tok item map)

       | otherwise        = map

 

-extractExps :: ParserInfo -> CId -> State -> [Exp]

-extractExps pinfo start (State chart items) = exps

+extractExps :: ParseState -> CId -> [Exp]

+extractExps (State pinfo chart items) start = exps

   where

     (_,st) = process (\_ _ -> id) (allRules pinfo) (Set.toList items) ((),chart)

 

@@ -160,7 +165,9 @@ data PassiveKey
   deriving (Eq,Ord,Show)

 

 

-data State = State Chart (Set.Set Active)

+-- | An abstract data type whose values represent

+-- the current state in an incremental parser.

+data ParseState = State ParserInfo Chart (Set.Set Active)

 

 data Chart

   = Chart