mirror of
https://github.com/idris-lang/Idris2.git
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ce44d3b50a
* Add trailing newline on non-empty list in unlines There are several reasons to do that: * a line in a text file is something which ends with newline, and the last line is not special * `unlines []` should be different from `unlines [""]` * `unlines (a ++ b) = unlines a ++ unlines b` * Haskell does it * Change lines function behaviour
390 lines
11 KiB
Idris
390 lines
11 KiB
Idris
module Data.String
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import Data.List
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import Data.List1
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%default total
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export
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singleton : Char -> String
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singleton c = strCons c ""
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||| Create a string by using n copies of a character
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export
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replicate : Nat -> Char -> String
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replicate n c = pack (replicate n c)
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||| Indent a given string by `n` spaces.
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public export
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indent : (n : Nat) -> String -> String
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indent n x = replicate n ' ' ++ x
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||| Pad a string on the left
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export
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padLeft : Nat -> Char -> String -> String
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padLeft n c str = replicate (minus n (String.length str)) c ++ str
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||| Pad a string on the right
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export
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padRight : Nat -> Char -> String -> String
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padRight n c str = str ++ replicate (minus n (String.length str)) c
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partial
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foldr1 : (a -> a -> a) -> List a -> a
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foldr1 _ [x] = x
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foldr1 f (x::xs) = f x (foldr1 f xs)
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partial
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foldl1 : (a -> a -> a) -> List a -> a
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foldl1 f (x::xs) = foldl f x xs
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-- This uses fastConcat internally so it won't compute at compile time.
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export
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fastUnlines : List String -> String
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fastUnlines = fastConcat . unlines'
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where unlines' : List String -> List String
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unlines' [] = []
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unlines' (x :: xs) = x :: "\n" :: unlines' xs
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-- This is a deprecated alias for fastConcat for backwards compatibility
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-- (unfortunately, we don't have %deprecated yet).
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export
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fastAppend : List String -> String
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fastAppend = fastConcat
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||| Splits a character list into a list of whitespace separated character lists.
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|||
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||| ```idris example
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||| words' (unpack " A B C D E ")
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||| ```
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covering
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words' : List Char -> List (List Char)
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words' s = case dropWhile isSpace s of
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[] => []
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s' => let (w, s'') = break isSpace s'
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in w :: words' s''
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||| Splits a string into a list of whitespace separated strings.
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|||
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||| ```idris example
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||| words " A B C D E "
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||| ```
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export
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covering
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words : String -> List String
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words s = map pack (words' (unpack s))
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||| Joins the character lists by spaces into a single character list.
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|||
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||| ```idris example
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||| unwords' [['A'], ['B', 'C'], ['D'], ['E']]
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||| ```
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unwords' : List (List Char) -> List Char
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unwords' [] = []
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unwords' ws = assert_total (foldr1 addSpace ws) where
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addSpace : List Char -> List Char -> List Char
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addSpace w s = w ++ (' ' :: s)
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||| Joins the strings by spaces into a single string.
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|||
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||| ```idris example
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||| unwords ["A", "BC", "D", "E"]
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||| ```
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export
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unwords : List String -> String
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unwords = pack . unwords' . map unpack
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||| Splits a character list into a list of newline separated character lists.
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|||
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||| ```idris example
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||| lines' (unpack "\rA BC\nD\r\nE\n")
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||| ```
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export
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lines' : List Char -> List (List Char)
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lines' s = linesHelp [] s
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where linesHelp : List Char -> List Char -> List (List Char)
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linesHelp [] [] = []
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linesHelp acc [] = [reverse acc]
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linesHelp acc ('\n' :: xs) = reverse acc :: linesHelp [] xs
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linesHelp acc ('\r' :: '\n' :: xs) = reverse acc :: linesHelp [] xs
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linesHelp acc ('\r' :: xs) = reverse acc :: linesHelp [] xs
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linesHelp acc (c :: xs) = linesHelp (c :: acc) xs
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||| Splits a string into a list of newline separated strings.
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|||
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||| ```idris example
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||| lines "\rA BC\nD\r\nE\n"
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||| ```
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export
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lines : String -> List String
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lines s = map pack (lines' (unpack s))
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||| Joins the character lists by a single character list by appending a newline
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||| to each line.
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|||
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||| ```idris example
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||| unlines' [['l','i','n','e'], ['l','i','n','e','2'], ['l','n','3'], ['D']]
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||| ```
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export
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unlines' : List (List Char) -> List Char
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unlines' [] = []
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unlines' (l::ls) = l ++ '\n' :: unlines' ls
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||| Joins the strings into a single string by appending a newline to each string.
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|||
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||| ```idris example
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||| unlines ["line", "line2", "ln3", "D"]
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||| ```
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export
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unlines : List String -> String
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unlines = pack . unlines' . map unpack
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%transform "fastUnlines" unlines = fastUnlines
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||| A view checking whether a string is empty
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||| and, if not, returning its head and tail
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public export
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data StrM : String -> Type where
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StrNil : StrM ""
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StrCons : (x : Char) -> (xs : String) -> StrM (strCons x xs)
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||| To each string we can associate its StrM view
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public export
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strM : (x : String) -> StrM x
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strM "" = StrNil
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strM x
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-- Using primitives, so `assert_total` and `believe_me` needed
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= assert_total $ believe_me $
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StrCons (prim__strHead x) (prim__strTail x)
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||| A view of a string as a lazy linked list of characters
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public export
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data AsList : String -> Type where
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Nil : AsList ""
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(::) : (c : Char) -> {str : String} -> Lazy (AsList str) -> AsList (strCons c str)
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||| To each string we can associate the lazy linked list of characters
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||| it corresponds to once unpacked.
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public export
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asList : (str : String) -> AsList str
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asList str with (strM str)
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asList "" | StrNil = []
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asList str@(strCons x xs) | StrCons _ _ = x :: asList (assert_smaller str xs)
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||| Trim whitespace on the left of the string
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export
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ltrim : String -> String
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ltrim str with (asList str)
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ltrim "" | [] = ""
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ltrim str@_ | x :: xs = if isSpace x then ltrim _ | xs else str
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||| Trim whitespace on both sides of the string
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export
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trim : String -> String
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trim = ltrim . reverse . ltrim . reverse
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||| Splits the string into a part before the predicate
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||| returns False and the rest of the string.
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|||
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||| ```idris example
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||| span (/= 'C') "ABCD"
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||| ```
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||| ```idris example
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||| span (/= 'C') "EFGH"
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||| ```
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export
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span : (Char -> Bool) -> String -> (String, String)
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span p xs
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= case span p (unpack xs) of
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(x, y) => (pack x, pack y)
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||| Splits the string into a part before the predicate
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||| returns True and the rest of the string.
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|||
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||| ```idris example
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||| break (== 'C') "ABCD"
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||| ```
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||| ```idris example
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||| break (== 'C') "EFGH"
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||| ```
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public export
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break : (Char -> Bool) -> String -> (String, String)
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break p = span (not . p)
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||| Splits the string into parts with the predicate
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||| indicating separator characters.
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|||
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||| ```idris example
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||| split (== '.') ".AB.C..D"
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||| ```
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public export
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split : (Char -> Bool) -> String -> List1 String
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split p xs = map pack (split p (unpack xs))
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export
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stringToNatOrZ : String -> Nat
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stringToNatOrZ = fromInteger . prim__cast_StringInteger
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export
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toUpper : String -> String
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toUpper str = pack (map toUpper (unpack str))
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export
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toLower : String -> String
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toLower str = pack (map toLower (unpack str))
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export partial
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strIndex : String -> Int -> Char
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strIndex = prim__strIndex
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export partial
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strLength : String -> Int
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strLength = prim__strLength
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export partial
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strSubstr : Int -> Int -> String -> String
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strSubstr = prim__strSubstr
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export partial
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strTail : String -> String
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strTail = prim__strTail
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export
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isPrefixOf : String -> String -> Bool
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isPrefixOf a b = isPrefixOf (unpack a) (unpack b)
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export
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isSuffixOf : String -> String -> Bool
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isSuffixOf a b = isSuffixOf (unpack a) (unpack b)
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export
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isInfixOf : String -> String -> Bool
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isInfixOf a b = isInfixOf (unpack a) (unpack b)
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parseNumWithoutSign : List Char -> Integer -> Maybe Integer
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parseNumWithoutSign [] acc = Just acc
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parseNumWithoutSign (c :: cs) acc =
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if (c >= '0' && c <= '9')
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then parseNumWithoutSign cs ((acc * 10) + (cast ((ord c) - (ord '0'))))
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else Nothing
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||| Convert a positive number string to a Num.
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||| ```idris example
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||| parsePositive "123"
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||| ```
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||| ```idris example
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||| parsePositive {a=Int} " +123"
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||| ```
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public export
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parsePositive : Num a => String -> Maybe a
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parsePositive s = parsePosTrimmed (trim s)
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where
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parsePosTrimmed : String -> Maybe a
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parsePosTrimmed s with (strM s)
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parsePosTrimmed "" | StrNil = Nothing
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parsePosTrimmed (strCons '+' xs) | (StrCons '+' xs) =
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map fromInteger (parseNumWithoutSign (unpack xs) 0)
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parsePosTrimmed (strCons x xs) | (StrCons x xs) =
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if (x >= '0' && x <= '9')
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then map fromInteger (parseNumWithoutSign (unpack xs) (cast (ord x - ord '0')))
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else Nothing
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||| Convert a number string to a Num.
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||| ```idris example
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||| parseInteger " 123"
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||| ```
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||| ```idris example
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||| parseInteger {a=Int} " -123"
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||| ```
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public export
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parseInteger : (Num a, Neg a) => String -> Maybe a
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parseInteger s = parseIntTrimmed (trim s)
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where
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parseIntTrimmed : String -> Maybe a
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parseIntTrimmed s with (strM s)
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parseIntTrimmed "" | StrNil = Nothing
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parseIntTrimmed (strCons x xs) | (StrCons x xs) =
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if (x == '-')
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then map (\y => negate (fromInteger y)) (parseNumWithoutSign (unpack xs) 0)
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else if (x == '+')
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then map fromInteger (parseNumWithoutSign (unpack xs) (cast {from=Int} 0))
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else if (x >= '0' && x <= '9')
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then map fromInteger (parseNumWithoutSign (unpack xs) (cast (ord x - ord '0')))
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else Nothing
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||| Convert a number string to a Double.
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||| ```idris example
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||| parseDouble "+123.123e-2"
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||| ```
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||| ```idris example
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||| parseDouble {a=Int} " -123.123E+2"
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||| ```
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||| ```idris example
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||| parseDouble {a=Int} " +123.123"
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||| ```
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export -- it's a bit too slow at compile time
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covering
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parseDouble : String -> Maybe Double
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parseDouble = mkDouble . wfe . trim
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where
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intPow : Integer -> Integer -> Double
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intPow base exp = assert_total $ if exp > 0 then (num base exp) else 1 / (num base exp)
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where
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num : Integer -> Integer -> Double
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num base 0 = 1
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num base e = if e < 0
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then cast base * num base (e + 1)
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else cast base * num base (e - 1)
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natpow : Double -> Nat -> Double
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natpow x Z = 1
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natpow x (S n) = x * (natpow x n)
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mkDouble : Maybe (Double, Double, Integer) -> Maybe Double
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mkDouble (Just (w, f, e)) = let ex = intPow 10 e in
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Just $ (w * ex + f * ex)
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mkDouble Nothing = Nothing
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wfe : String -> Maybe (Double, Double, Integer)
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wfe cs = case split (== '.') cs of
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(wholeAndExp ::: []) =>
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case split (\c => c == 'e' || c == 'E') wholeAndExp of
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(whole:::exp::[]) =>
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do
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w <- cast {from=Integer} <$> parseInteger whole
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e <- parseInteger exp
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pure (w, 0, e)
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(whole:::[]) =>
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do
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w <- cast {from=Integer} <$> parseInteger whole
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pure (w, 0, 0)
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_ => Nothing
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(whole:::fracAndExp::[]) =>
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case split (\c => c == 'e' || c == 'E') fracAndExp of
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("":::exp::[]) => Nothing
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(frac:::exp::[]) =>
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do
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w <- cast {from=Integer} <$> parseInteger whole
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f <- (/ (natpow 10 (length frac))) <$>
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(cast <$> parseNumWithoutSign (unpack frac) 0)
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e <- parseInteger exp
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pure (w, if w < 0 then (-f) else f, e)
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(frac:::[]) =>
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do
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w <- cast {from=Integer} <$> parseInteger whole
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f <- (/ (natpow 10 (length frac))) <$>
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(cast <$> parseNumWithoutSign (unpack frac) 0)
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pure (w, if w < 0 then (-f) else f, 0)
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_ => Nothing
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_ => Nothing
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public export
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null : String -> Bool
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null = (== "")
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