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module Database.ERD
( ERD(..), ERDName, Entity(..), EName, Entity(..)
, Attribute(..), AName, Key(..), Null, Domain(..)
, Relationship(..), REnd(..), RName, Role, Cardinality(..), MaxValue(..)
, readERDTermFile, writeERDTermFile
) where
import Char (isSpace)
import Directory (getAbsolutePath)
import IO
import ReadShowTerm (readUnqualifiedTerm)
import Time
data ERD = ERD ERDName [Entity] [Relationship]
type ERDName = String
data Entity = Entity EName [Attribute]
type EName = String
data Attribute = Attribute AName Domain Key Null
type AName = String
data Key = NoKey
| PKey
| Unique
type Null = Bool
data Domain = IntDom (Maybe Int)
| FloatDom (Maybe Float)
| CharDom (Maybe Char)
| StringDom (Maybe String)
| BoolDom (Maybe Bool)
| DateDom (Maybe CalendarTime)
| UserDefined String (Maybe String)
| KeyDom String
data Relationship = Relationship RName [REnd]
type RName = String
data REnd = REnd EName Role Cardinality
type Role = String
data Cardinality = Exactly Int
| Between Int MaxValue
data MaxValue = Max Int | Infinite
readERDTermFile :: String -> IO ERD
readERDTermFile termfilename = do
putStrLn $ "Reading ERD term from file '" ++ termfilename ++ "'..."
handle <- openFile termfilename ReadMode
line <- skipCommentLines handle
termstring <- hGetContents handle
return (updateERDTerm (readUnqualifiedTerm ["Database.ERD","Prelude"]
(unlines [line,termstring])))
where
h = do
line <- hGetLine h >>= return . dropWhile isSpace
if null line || take 2 line == "--"
then skipCommentLines h
else if take 2 line == "{-"
then skipBracketComment h (drop 2 line)
else return line
h [] = hGetLine h >>= skipBracketComment h
skipBracketComment h [_] = hGetLine h >>= skipBracketComment h
skipBracketComment h (c1:c2:cs) =
if c1=='-' && c2=='}' then return cs
else skipBracketComment h (c2:cs)
updateERDTerm :: ERD -> ERD
updateERDTerm (ERD name es rs) = ERD name es (map updateRel rs)
where
updateRel (Relationship r ends) = Relationship r (map updateEnd ends)
updateEnd (REnd n r c) = REnd n r (updateCard c)
updateCard (Exactly n) = Exactly n
updateCard (Between min (Max m)) =
if min<=m
then Between min (Max m)
else error ("ERD: Illegal cardinality " ++ show (Between min (Max m)))
updateCard (Between min Infinite) = Between min Infinite
writeERDTermFile :: ERD -> IO String
writeERDTermFile erd@(ERD name _ _) = do
let termfile = name ++ ".erdterm"
writeFile termfile (show erd)
getAbsolutePath termfile
|