git.iko.soy/elk
on fa9bfb9 help sign in
elk/src/Nitpick/Pattern.hs
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1module Nitpick.Pattern where
3import qualified Data.List as List
4import qualified Data.Set as Set
6import qualified AST.Literal as L
7import qualified AST.Pattern as P
8import qualified AST.Variable as Var
9import qualified Reporting.Annotation as A
12data Pattern
13 = Data Var.Canonical [Pattern]
14 | Record [String]
15 | Alias String Pattern
16 | Var String
17 | Anything
18 | Literal L.Literal
19 | AnythingBut (Set.Set L.Literal)
20 deriving (Show, Eq)
23fromCanonicalPattern :: P.CanonicalPattern -> Pattern
24fromCanonicalPattern (A.A _ pattern) =
25 case pattern of
26 P.Data tag patterns ->
27 Data tag (map fromCanonicalPattern patterns)
29 P.Record fields ->
30 Record fields
32 P.Alias name pattern ->
33 Alias name (fromCanonicalPattern pattern)
35 P.Var name ->
36 Var name
38 P.Anything ->
39 Anything
41 P.Literal literal ->
42 Literal literal
45-- TO STRING
47toString :: Bool -> Pattern -> String
48toString needsParens pattern =
49 case pattern of
50 Data tag [first,rest] | Var.toString tag == "::" ->
51 toString (isCons first) first
52 ++ " :: "
53 ++ toString False rest
55 Data tag args ->
56 if Var.isTuple tag then
57 "(" ++ List.intercalate ", " (map (toString False) args) ++ ")"
59 else
60 addParensIf (needsParens && not (null args)) $
61 List.intercalate " " (Var.toString tag : map (toString True) args)
63 Record fields ->
64 "{ " ++ List.intercalate ", " fields ++ " }"
66 Alias alias realPattern ->
67 addParensIf needsParens $
68 toString False realPattern ++ " as " ++ alias
70 Var name ->
71 name
73 Anything ->
74 "_"
76 Literal literal ->
77 L.toString literal
79 AnythingBut literalSet ->
80 List.intercalate " " ("<values besides:" : map L.toString (Set.toList literalSet) ++ [">"])
83addParensIf :: Bool -> String -> String
84addParensIf needsParens str =
85 if needsParens then
86 "(" ++ str ++ ")"
88 else
89 str
92isCons :: Pattern -> Bool
93isCons pattern =
94 case pattern of
95 Data tag [_,_] ->
96 Var.toString tag == "::"
98 _ ->
99 False