Files
gf-core/src-3.0/GF/UseGrammar/MatchTerm.hs

51 lines
1.4 KiB
Haskell

----------------------------------------------------------------------
-- |
-- Module : MatchTerm
-- Maintainer : AR
-- Stability : (stable)
-- Portability : (portable)
--
--
-- functions for matching with terms. AR 16/3/2006
-----------------------------------------------------------------------------
module GF.UseGrammar.MatchTerm where
import GF.Data.Operations
import GF.Data.Zipper
import GF.Grammar.Grammar
import GF.Grammar.PrGrammar
import GF.Infra.Ident
import GF.Grammar.Values
import GF.Grammar.Macros
import GF.Grammar.MMacros
import Control.Monad
import Data.List
-- test if a term has duplicated idents, either any or just atoms
hasDupIdent, hasDupAtom :: Exp -> Bool
hasDupIdent = (>1) . maximum . map length . group . sort . allConstants True
hasDupAtom = (>1) . maximum . map length . group . sort . allConstants False
-- test if a certain ident occurs in term
grepIdent :: Ident -> Exp -> Bool
grepIdent c = elem c . allConstants True
-- form the list of all constants, optionally ignoring all but atoms
allConstants :: Bool -> Exp -> [Ident]
allConstants alsoApp = err (const []) snd . flip appSTM [] . collect where
collect e = case e of
Q _ c -> add c e
QC _ c -> add c e
Cn c -> add c e
App f a | not alsoApp -> case f of
App g b -> collect b >> collect a
_ -> collect a
_ -> composOp collect e
add c e = updateSTM (c:) >> return e