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(;module:
[lux #- not]
(lux (control functor
applicative
[monad #+ do Monad]
["p" parser])
(data [text "text/" Monoid<Text>]
[product]
[maybe]
["R" result]
(coll [list "L/" Functor<List>]))))
(type: Offset Nat)
(def: start-offset Offset +0)
(type: #export Lexer
(p;Parser [Offset Text]))
(def: (remaining offset tape)
(-> Offset Text Text)
(|> tape (text;split offset) assume product;right))
(def: cannot-lex-error Text "Cannot lex from empty text.")
(def: (unconsumed-input-error offset tape)
(-> Offset Text Text)
($_ text/append "Unconsumed input: " (remaining offset tape)))
(def: #export (run input lexer)
(All [a] (-> Text (Lexer a) (R;Result a)))
(case (lexer [start-offset input])
(#R;Error msg)
(#R;Error msg)
(#R;Success [[end-offset _] output])
(if (n.= end-offset (text;size input))
(#R;Success output)
(#R;Error (unconsumed-input-error end-offset input)))
))
(def: #export any
{#;doc "Just returns the next character without applying any logic."}
(Lexer Text)
(function [[offset tape]]
(case (text;nth offset tape)
(#;Some output)
(#R;Success [[(n.inc offset) tape] (text;from-code output)])
_
(#R;Error cannot-lex-error))
))
(def: #export (not p)
{#;doc "Produce a character if the lexer fails."}
(All [a] (-> (Lexer a) (Lexer Text)))
(function [input]
(case (p input)
(#R;Error msg)
(any input)
_
(#R;Error "Expected to fail; yet succeeded."))))
(def: #export (this reference)
{#;doc "Lex a text if it matches the given sample."}
(-> Text (Lexer Unit))
(function [[offset tape]]
(case (text;index-of reference offset tape)
(^multi (#;Some where) (n.= offset where))
(#R;Success [[(n.+ (text;size reference) offset) tape] []])
_
(#R;Error ($_ text/append "Could not match: " (text;encode reference) " @ " tape)))))
(def: #export (this? reference)
{#;doc "Lex a text if it matches the given sample."}
(-> Text (Lexer Bool))
(function [(^@ input [offset tape])]
(case (text;index-of reference offset tape)
(^multi (#;Some where) (n.= offset where))
(#R;Success [[(n.+ (text;size reference) offset) tape] true])
_
(#R;Success [input false]))))
(def: #export end
{#;doc "Ensure the lexer's input is empty."}
(Lexer Unit)
(function [(^@ input [offset tape])]
(if (n.= offset (text;size tape))
(#R;Success [input []])
(#R;Error (unconsumed-input-error offset tape)))))
(def: #export end?
{#;doc "Ask if the lexer's input is empty."}
(Lexer Bool)
(function [(^@ input [offset tape])]
(#R;Success [input (n.= offset (text;size tape))])))
(def: #export peek
{#;doc "Lex the next character (without consuming it from the input)."}
(Lexer Text)
(function [(^@ input [offset tape])]
(case (text;nth offset tape)
(#;Some output)
(#R;Success [input (text;from-code output)])
_
(#R;Error cannot-lex-error))
))
(def: #export get-input
{#;doc "Get all of the remaining input (without consuming it)."}
(Lexer Text)
(function [(^@ input [offset tape])]
(#R;Success [input (remaining offset tape)])))
(def: #export (range bottom top)
{#;doc "Only lex characters within a range."}
(-> Nat Nat (Lexer Text))
(do p;Monad<Parser>
[char any
#let [char' (assume (text;nth +0 char))]
_ (p;assert ($_ text/append "Character is not within range: " (text;from-code bottom) "-" (text;from-code top))
(and (n.>= bottom char')
(n.<= top char')))]
(wrap char)))
(do-template [<name> <bottom> <top> <desc>]
[(def: #export <name>
{#;doc (#;TextA ($_ text/append "Only lex " <desc> " characters."))}
(Lexer Text)
(range (char <bottom>) (char <top>)))]
[upper "A" "Z" "uppercase"]
[lower "a" "z" "lowercase"]
[decimal "0" "9" "decimal"]
[octal "0" "7" "octal"]
)
(def: #export alpha
{#;doc "Only lex alphabetic characters."}
(Lexer Text)
(p;either lower upper))
(def: #export alpha-num
{#;doc "Only lex alphanumeric characters."}
(Lexer Text)
(p;either alpha decimal))
(def: #export hexadecimal
{#;doc "Only lex hexadecimal digits."}
(Lexer Text)
($_ p;either
decimal
(range (char "a") (char "f"))
(range (char "A") (char "F"))))
(def: #export (one-of options)
{#;doc "Only lex characters that are part of a piece of text."}
(-> Text (Lexer Text))
(function [[offset tape]]
(case (text;nth offset tape)
(#;Some output)
(let [output (text;from-code output)]
(if (text;contains? output options)
(#R;Success [[(n.inc offset) tape] output])
(#R;Error ($_ text/append "Character (" output ") is not one of: " options))))
_
(#R;Error cannot-lex-error))))
(def: #export (none-of options)
{#;doc "Only lex characters that are not part of a piece of text."}
(-> Text (Lexer Text))
(function [[offset tape]]
(case (text;nth offset tape)
(#;Some output)
(let [output (text;from-code output)]
(if (;not (text;contains? output options))
(#R;Success [[(n.inc offset) tape] output])
(#R;Error ($_ text/append "Character (" output ") is one of: " options))))
_
(#R;Error cannot-lex-error))))
(def: #export (satisfies p)
{#;doc "Only lex characters that satisfy a predicate."}
(-> (-> Nat Bool) (Lexer Text))
(function [[offset tape]]
(case (text;nth offset tape)
(#;Some output)
(if (p output)
(#R;Success [[(n.inc offset) tape] (text;from-code output)])
(#R;Error ($_ text/append "Character does not satisfy predicate: " (text;from-code output))))
_
(#R;Error cannot-lex-error))))
(def: #export space
{#;doc "Only lex white-space."}
(Lexer Text)
(satisfies text;space?))
(def: #export (seq left right)
(-> (Lexer Text) (Lexer Text) (Lexer Text))
(do p;Monad<Parser>
[=left left
=right right]
(wrap ($_ text/append =left =right))))
(do-template [<name> <base> <doc>]
[(def: #export (<name> p)
{#;doc <doc>}
(-> (Lexer Text) (Lexer Text))
(|> p <base> (:: p;Monad<Parser> map text;concat)))]
[some p;some "Lex some characters as a single continuous text."]
[many p;many "Lex many characters as a single continuous text."]
)
(do-template [<name> <base> <doc>]
[(def: #export (<name> n p)
{#;doc <doc>}
(-> Nat (Lexer Text) (Lexer Text))
(do p;Monad<Parser>
[]
(|> p (<base> n) (:: @ map text;concat))))]
[exactly p;exactly "Lex exactly N characters."]
[at-most p;at-most "Lex at most N characters."]
[at-least p;at-least "Lex at least N characters."]
)
(def: #export (between from to p)
{#;doc "Lex between N and M characters."}
(-> Nat Nat (Lexer Text) (Lexer Text))
(|> p (p;between from to) (:: p;Monad<Parser> map text;concat)))
(def: #export (enclosed [start end] lexer)
(All [a] (-> [Text Text] (Lexer a) (Lexer a)))
(|> lexer
(p;before (this end))
(p;after (this start))))
(def: #export (local local-input lexer)
{#;doc "Run a lexer with the given input, instead of the real one."}
(All [a] (-> Text (Lexer a) (Lexer a)))
(function [real-input]
(case (run local-input lexer)
(#R;Error error)
(#R;Error error)
(#R;Success value)
(#R;Success [real-input value]))))
|
