1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
|
----------------------------------------------------------------------
-- |
-- Module : Parsers
-- Maintainer : Aarne Ranta
-- Stability : Almost Obsolete
-- Portability : Haskell 98
--
-- > CVS $Date: 2005/02/24 11:46:35 $
-- > CVS $Author: peb $
-- > CVS $Revision: 1.5 $
--
-- some parser combinators a la Wadler and Hutton.
-- no longer used in many places in GF
-- (only used in module "EBNF")
-----------------------------------------------------------------------------
module Parsers (-- * Main types and functions
Parser, parseResults, parseResultErr,
-- * Basic combinators (on any token type)
(...), (.>.), (|||), (+||), literal, (***),
succeed, fails, (+..), (..+), (<<<), (|>),
many, some, longestOfMany, longestOfSome,
closure,
-- * Specific combinators (for @Char@ token type)
pJunk, pJ, jL, pTList, pTJList, pElem,
(....), item, satisfy, literals, lits,
pParenth, pCommaList, pOptCommaList,
pArgList, pArgList2,
pIdent, pLetter, pDigit, pLetters,
pAlphanum, pAlphaPlusChar,
pQuotedString, pIntc
) where
import Operations
import Char
infixr 2 |||, +||
infixr 3 ***
infixr 5 .>.
infixr 5 ...
infixr 5 ....
infixr 5 +..
infixr 5 ..+
infixr 6 |>
infixr 3 <<<
type Parser a b = [a] -> [(b,[a])]
parseResults :: Parser a b -> [a] -> [b]
parseResults p s = [x | (x,r) <- p s, null r]
parseResultErr :: Parser a b -> [a] -> Err b
parseResultErr p s = case parseResults p s of
[x] -> return x
[] -> Bad "no parse"
_ -> Bad "ambiguous"
(...) :: Parser a b -> Parser a c -> Parser a (b,c)
(p ... q) s = [((x,y),r) | (x,t) <- p s, (y,r) <- q t]
(.>.) :: Parser a b -> (b -> Parser a c) -> Parser a c
(p .>. f) s = [(c,r) | (x,t) <- p s, (c,r) <- f x t]
(|||) :: Parser a b -> Parser a b -> Parser a b
(p ||| q) s = p s ++ q s
(+||) :: Parser a b -> Parser a b -> Parser a b
p1 +|| p2 = take 1 . (p1 ||| p2)
literal :: (Eq a) => a -> Parser a a
literal x (c:cs) = [(x,cs) | x == c]
literal _ _ = []
(***) :: Parser a b -> (b -> c) -> Parser a c
(p *** f) s = [(f x,r) | (x,r) <- p s]
succeed :: b -> Parser a b
succeed v s = [(v,s)]
fails :: Parser a b
fails s = []
(+..) :: Parser a b -> Parser a c -> Parser a c
p1 +.. p2 = p1 ... p2 *** snd
(..+) :: Parser a b -> Parser a c -> Parser a b
p1 ..+ p2 = p1 ... p2 *** fst
(<<<) :: Parser a b -> c -> Parser a c -- return
p <<< v = p *** (\x -> v)
(|>) :: Parser a b -> (b -> Bool) -> Parser a b
p |> b = p .>. (\x -> if b x then succeed x else fails)
many :: Parser a b -> Parser a [b]
many p = (p ... many p *** uncurry (:)) +|| succeed []
some :: Parser a b -> Parser a [b]
some p = (p ... many p) *** uncurry (:)
longestOfMany :: Parser a b -> Parser a [b]
longestOfMany p = p .>. (\x -> longestOfMany p *** (x:)) +|| succeed []
closure :: (b -> Parser a b) -> (b -> Parser a b)
closure p v = p v .>. closure p ||| succeed v
pJunk :: Parser Char String
pJunk = longestOfMany (satisfy (\x -> elem x "\n\t "))
pJ :: Parser Char a -> Parser Char a
pJ p = pJunk +.. p ..+ pJunk
pTList :: String -> Parser Char a -> Parser Char [a]
pTList t p = p .... many (jL t +.. p) *** (\ (x,y) -> x:y) -- mod. AR 5/1/1999
pTJList :: String -> String -> Parser Char a -> Parser Char [a]
pTJList t1 t2 p = p .... many (literals t1 +.. jL t2 +.. p) *** (uncurry (:))
pElem :: [String] -> Parser Char String
pElem l = foldr (+||) fails (map literals l)
(....) :: Parser Char b -> Parser Char c -> Parser Char (b,c)
p1 .... p2 = p1 ... pJunk +.. p2
item :: Parser a a
item (c:cs) = [(c,cs)]
item [] = []
satisfy :: (a -> Bool) -> Parser a a
satisfy b = item |> b
literals :: (Eq a,Show a) => [a] -> Parser a [a]
literals l = case l of
[] -> succeed []
a:l -> literal a ... literals l *** (\ (x,y) -> x:y)
lits :: (Eq a,Show a) => [a] -> Parser a [a]
lits ts = literals ts
jL :: String -> Parser Char String
jL = pJ . lits
pParenth :: Parser Char a -> Parser Char a
pParenth p = literal '(' +.. pJunk +.. p ..+ pJunk ..+ literal ')'
-- | p,...,p
pCommaList :: Parser Char a -> Parser Char [a]
pCommaList p = pTList "," (pJ p)
-- | the same or nothing
pOptCommaList :: Parser Char a -> Parser Char [a]
pOptCommaList p = pCommaList p ||| succeed []
-- | (p,...,p), poss. empty
pArgList :: Parser Char a -> Parser Char [a]
pArgList p = pParenth (pCommaList p) ||| succeed []
-- | min. 2 args
pArgList2 :: Parser Char a -> Parser Char [a]
pArgList2 p = pParenth (p ... jL "," +.. pCommaList p) *** uncurry (:)
longestOfSome :: Parser a b -> Parser a [b]
longestOfSome p = (p ... longestOfMany p) *** (\ (x,y) -> x:y)
pIdent :: Parser Char String
pIdent = pLetter ... longestOfMany pAlphaPlusChar *** uncurry (:)
where alphaPlusChar c = isAlphaNum c || c=='_' || c=='\''
pLetter, pDigit :: Parser Char Char
pLetter = satisfy (`elem` (['A'..'Z'] ++ ['a'..'z'] ++
['À' .. 'Û'] ++ ['à' .. 'û'])) -- no such in Char
pDigit = satisfy isDigit
pLetters :: Parser Char String
pLetters = longestOfSome pLetter
pAlphanum, pAlphaPlusChar :: Parser Char Char
pAlphanum = pDigit ||| pLetter
pAlphaPlusChar = pAlphanum ||| satisfy (`elem` "_'")
pQuotedString :: Parser Char String
pQuotedString = literal '"' +.. pEndQuoted where
pEndQuoted =
literal '"' *** (const [])
+|| (literal '\\' +.. item .>. \ c -> pEndQuoted *** (c:))
+|| item .>. \ c -> pEndQuoted *** (c:)
pIntc :: Parser Char Int
pIntc = some (satisfy numb) *** read
where numb x = elem x ['0'..'9']
|
