SQLParserInfoType.curry 5.6 KB
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--- This module defines the structure of the parser information
--- used to pass information of the data model from an ERD-term to
--- the SQL-Translator which is part of currypp.
--- It consists of a tuple of the path to the corresponding database as string,
--- and the name of the corresponding CDBI-module as String,
--- a list or tupels mapping relationships to their types,
--- a list of tupels representing column names and a nullable flag,
--- a list of tupels of table name and list of corresponding column names,
--- a list of tupels representing column name and its type as string.
--- Furthermore a getter function for each part of the information
--- is defined returning it as FM instead of a list. A lookup function for 
--- relationships is provided either.
---@author: Julia Krone
-- ----------------------------------------------------------------------------
module SQLParserInfoType 
 (dbName, getRelations, getNullables, getAttrList, RelationType(..), 
  ParserInfo(..), getTypes, lookupRel, RelationFM, cdbiModule,
  NullableFM, AttributesFM, AttrTypeFM)
where 

import Char(toLower)
import FiniteMap
import List(partition)

--- Type synonyms for all parts of the parser information
type RelationFM = FM String (FM String [(String, RelationType)])
type RelationTypes = [((String, String, String), RelationType)]

type NullableFlags =  [(String, Bool)]
type NullableFM = FM String Bool

type AttributeLists =  [(String,(String, [String]))]
type AttributesFM = FM String (String, [String]) 

type AttributeTypes = [(String, String)] 
type AttrTypeFM = FM String String 

--- Basic data type for parser information.
data ParserInfo = PInfo (String, String) 
                        RelationTypes
                        NullableFlags
                        AttributeLists
                        AttributeTypes 
                      
--- Data type representing possible relationships in the relational model.                        
data RelationType = MtoN String 
                   | NtoOne String 
                   | OnetoN String 

--- Getter for path to used database.
dbName :: ParserInfo -> String
dbName (PInfo (db,_) _ _ _ _ ) = db

--- Getter for CDBI-module-name
cdbiModule :: ParserInfo -> String
cdbiModule (PInfo (_, cdbi) _ _ _ _) = cdbi

--- Getter for relationships represented as nested FM for faster access.
getRelations :: ParserInfo -> RelationFM 
getRelations (PInfo _ rels _ _ _) = splitRelations rels

--- Getter for nullable-flag returned as a FM
getNullables :: ParserInfo -> NullableFM 
getNullables (PInfo _ _ nulls _ _) =  listToFM (>) nulls

--- Getter for for lists of attributes (columns)
--- returned as FM.
getAttrList :: ParserInfo -> AttributesFM
getAttrList (PInfo _ _ _ attrs _ ) = listToFM (>) attrs

--- Getter for column types returnd as FM.
getTypes :: ParserInfo -> AttrTypeFM 
getTypes (PInfo _ _ _ _ types) = listToFM (>) types

--- Lookup function for RelationFM.
--- In case of success return tuple of relation type
--- and original notation.
lookupRel :: (String, String, String) -> 
             RelationFM -> 
             Maybe (RelationType, String)
lookupRel (e1,rel,e2) fm = 
  case lookupFM fm e1 of
    Nothing  -> Nothing
    Just fm2 -> case lookupFM fm2 e2 of
                   Nothing -> Nothing
                   Just rels -> fetchRel rel rels
  where fetchRel _ [] = Nothing
        fetchRel rName ((relName, relType):rs) = 
              if (toLowerCase rName) == (toLowerCase relName)
                then (Just (relType, relName))
                else fetchRel rName rs     

                
-- auxiliary functions for the transformation of a list of tupels to
-- a nested FM

splitRelations ::  [((String, String, String), RelationType)] -> RelationFM  
splitRelations [] = emptyFM (>)
splitRelations (r:rels) = 
  let (frst, rest) = selectFirstEntity (frsEnt r) (r:rels)
   in plusFM (createFM frst) (splitRelations rest)

frsEnt :: ((String, String, String), RelationType) ->  String
frsEnt ((ent, _ , _ ),_) = ent 

sndEnt :: ((String, String, String), RelationType) ->  String 
sndEnt (( _ , _ , ent ),_) = ent 

selectFirstEntity :: String -> [((String, String, String), RelationType)]
                            -> ([((String,String, String), RelationType)],
                                [((String, String, String), RelationType)]) 
selectFirstEntity name rels = partition (\(( n, _, _),_) -> n == name) rels

createFM :: [((String, String, String), RelationType)] -> RelationFM
createFM [] = emptyFM (>)
createFM (e:elems) = unitFM (>) (frsEnt e) (insertElems (e:elems))

insertElems :: [((String, String, String), RelationType)] ->
               (FM String [(String, RelationType)])
insertElems [] = emptyFM (>)
insertElems (e:elems) = let (snds, rest) = (selectSecondEntity (sndEnt e) 
                                                               (e:elems))  
                         in plusFM snds (insertElems rest)

selectSecondEntity :: String -> 
                      [((String, String, String), RelationType)] ->
                      ((FM String [(String, RelationType)]),
                          [((String, String, String), RelationType)])
selectSecondEntity name rels = 
  let (fit, nfit) = partition (\((_ , _, n),_) -> n == name) rels
   in ((createSubFM fit), nfit)
  where createSubFM [] = emptyFM (>)
        createSubFM (((_,r,e2),rt):rs) = unitFM (>) 
                                                e2 
                                                ((r,rt):(map selectRelation rs))

selectRelation :: ((String, String, String), RelationType) -> 
                  (String, RelationType)
selectRelation ((_ , r, _), rt) = (r, rt)
    

toLowerCase :: String -> String
toLowerCase str = map toLower str