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;; Copyright (c) Eduardo Julian. All rights reserved.
;; This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
;; If a copy of the MPL was not distributed with this file,
;; You can obtain one at http://mozilla.org/MPL/2.0/.
(ns lux.lexer
(:require (clojure [template :refer [do-template]]
[string :as string])
(lux [base :as & :refer [defvariant |do return* return fail fail* |case]]
[reader :as &reader])
[lux.analyser.module :as &module]))
;; [Tags]
(defvariant
("White_Space" 1)
("Comment" 1)
("Bool" 1)
("Nat" 1)
("Int" 1)
("Frac" 1)
("Real" 1)
("Char" 1)
("Text" 1)
("Symbol" 1)
("Tag" 1)
("Open_Paren" 0)
("Close_Paren" 0)
("Open_Bracket" 0)
("Close_Bracket" 0)
("Open_Brace" 0)
("Close_Brace" 0)
)
;; [Utils]
(defn ^:private escape-char [escaped]
"(-> Text (Lux Text))"
(cond (.equals ^Object escaped "\\t") (return "\t")
(.equals ^Object escaped "\\b") (return "\b")
(.equals ^Object escaped "\\n") (return "\n")
(.equals ^Object escaped "\\r") (return "\r")
(.equals ^Object escaped "\\f") (return "\f")
(.equals ^Object escaped "\\\"") (return "\"")
(.equals ^Object escaped "\\\\") (return "\\")
:else
(&/fail-with-loc (str "[Lexer Error] Unknown escape character: " escaped))))
(defn ^:private escape-char* [escaped]
"(-> Text Text)"
(cond (.equals ^Object escaped "\\t") "\t"
(.equals ^Object escaped "\\b") "\b"
(.equals ^Object escaped "\\n") "\n"
(.equals ^Object escaped "\\r") "\r"
(.equals ^Object escaped "\\f") "\f"
(.equals ^Object escaped "\\\"") "\""
(.equals ^Object escaped "\\\\") "\\"
:else
(assert false (str "[Lexer Error] Unknown escape character: " escaped))))
(defn ^:private clean-line [^String raw-line]
"(-> Text Text)"
(let [line-length (.length raw-line)
buffer (new StringBuffer line-length)]
(loop [idx 0]
(if (< idx line-length)
(let [current-char (.charAt raw-line idx)]
(if (= \\ current-char)
(do (assert (< (+ 1 idx) line-length) (str "[Lexer Error] Text is too short for escaping: " raw-line " " idx))
(case (.charAt raw-line (+ 1 idx))
\t (do (.append buffer "\t")
(recur (+ 2 idx)))
\b (do (.append buffer "\b")
(recur (+ 2 idx)))
\n (do (.append buffer "\n")
(recur (+ 2 idx)))
\r (do (.append buffer "\r")
(recur (+ 2 idx)))
\f (do (.append buffer "\f")
(recur (+ 2 idx)))
\" (do (.append buffer "\"")
(recur (+ 2 idx)))
\\ (do (.append buffer "\\")
(recur (+ 2 idx)))
\u (do (assert (< (+ 5 idx) line-length) (str "[Lexer Error] Text is too short for unicode-escaping: " raw-line " " idx))
(.append buffer (char (Integer/valueOf (.substring raw-line (+ 2 idx) (+ 6 idx)) 16)))
(recur (+ 6 idx)))
;; else
(assert false (str "[Lexer Error] Invalid escaping syntax: " raw-line " " idx))))
(do (.append buffer current-char)
(recur (+ 1 idx)))))
(.toString buffer)))))
(defn ^:private lex-text-body [multi-line? offset]
(|do [[_ eol? ^String pre-quotes**] (&reader/read-regex #"^([^\"]*)")
^String pre-quotes* (if multi-line?
(|do [:let [empty-line? (and eol? (= "" pre-quotes**))]
_ (&/assert! (or empty-line?
(>= (.length pre-quotes**) offset))
"Each line of a multi-line text must have an appropriate offset!")]
(return (if empty-line?
"\n"
(str "\n" (.substring pre-quotes** offset)))))
(return pre-quotes**))
[pre-quotes post-quotes] (if (.endsWith pre-quotes* "\\")
(if eol?
(&/fail-with-loc "[Lexer Error] Can't leave dangling back-slash \\")
(if (if-let [^String back-slashes (re-find #"\\+$" pre-quotes*)]
(odd? (.length back-slashes)))
(|do [[_ eol?* _] (&reader/read-regex #"^([\"])")
next-part (lex-text-body eol?* offset)]
(return (&/T [(.substring pre-quotes* 0 (dec (.length pre-quotes*)))
(str "\"" next-part)])))
(|do [post-quotes* (lex-text-body false offset)]
(return (&/T [pre-quotes* post-quotes*])))))
(if eol?
(|do [next-part (lex-text-body true offset)]
(return (&/T [pre-quotes*
next-part])))
(return (&/T [pre-quotes* ""]))))]
(return (str (clean-line pre-quotes) post-quotes))))
(def lex-text
(|do [[meta _ _] (&reader/read-text "\"")
:let [[_ _ _column] meta]
token (lex-text-body false (inc _column))
_ (&reader/read-text "\"")]
(return (&/T [meta ($Text token)]))))
(def +ident-re+
#"^([^0-9\[\]\{\}\(\)\s\"#;][^\[\]\{\}\(\)\s\"#;]*)")
;; [Lexers]
(def ^:private lex-white-space
(|do [[meta _ white-space] (&reader/read-regex #"^(\s+|$)")]
(return (&/T [meta ($White_Space white-space)]))))
(def ^:private lex-single-line-comment
(|do [_ (&reader/read-text "##")
[meta _ comment] (&reader/read-regex #"^(.*)$")]
(return (&/T [meta ($Comment comment)]))))
(defn ^:private lex-multi-line-comment [_]
(|do [_ (&reader/read-text "#(")
[meta comment] (&/try-all% (&/|list (|do [[meta comment] (&reader/read-regex+ #"(?is)^(?!#\()((?!\)#).)*")]
(return (&/T [meta comment])))
(|do [[meta pre] (&reader/read-regex+ #"(?is)^((?!#\().)*")
[_ ($Comment inner)] (lex-multi-line-comment nil)
[_ post] (&reader/read-regex+ #"(?is)^((?!\)#).)*")]
(return (&/T [meta (str pre "#(" inner ")#" post)])))))
_ (&reader/read-text ")#")]
(return (&/T [meta ($Comment comment)]))))
(def ^:private lex-comment
(&/try-all% (&/|list lex-single-line-comment
(lex-multi-line-comment nil))))
(do-template [<name> <tag> <regex>]
(def <name>
(|do [[meta _ token] (&reader/read-regex <regex>)]
(return (&/T [meta (<tag> token)]))))
lex-bool $Bool #"^(true|false)"
)
(do-template [<name> <tag> <regex>]
(def <name>
(|do [[meta _ token] (&reader/read-regex <regex>)]
(return (&/T [meta (<tag> (string/replace token #"_" ""))]))))
lex-nat $Nat #"^\+(0|[1-9][0-9_]*)"
lex-int $Int #"^-?(0|[1-9][0-9_]*)"
lex-frac $Frac #"^(\.[0-9_]+)"
lex-real $Real #"^-?(0\.[0-9_]+|[1-9][0-9_]*\.[0-9_]+)(e-?[1-9][0-9_]*)?"
)
(def lex-char
(|do [[meta _ _] (&reader/read-text "#\"")
token (&/try-all% (&/|list (|do [[_ _ escaped] (&reader/read-regex #"^(\\.)")]
(escape-char escaped))
(|do [[_ _ ^String unicode] (&reader/read-regex #"^(\\u[0-9a-fA-F]{4})")]
(return (str (char (Integer/valueOf (.substring unicode 2) 16)))))
(|do [[_ _ char] (&reader/read-regex #"^(.)")]
(return char))))
_ (&reader/read-text "\"")]
(return (&/T [meta ($Char token)]))))
(def ^:private lex-ident
(&/try-all-% "[Reader Error]"
(&/|list (|do [[meta _ token] (&reader/read-regex +ident-re+)
[_ _ got-it?] (&reader/read-text? ";")]
(|case got-it?
(&/$Some _)
(|do [[_ _ local-token] (&reader/read-regex +ident-re+)
? (&module/exists? token)]
(if ?
(return (&/T [meta (&/T [token local-token])]))
(|do [unaliased (&module/dealias token)]
(return (&/T [meta (&/T [unaliased local-token])])))))
(&/$None)
(return (&/T [meta (&/T ["" token])]))))
(|do [[meta _ _] (&reader/read-text ";;")
[_ _ token] (&reader/read-regex +ident-re+)
module-name &/get-module-name]
(return (&/T [meta (&/T [module-name token])])))
(|do [[meta _ _] (&reader/read-text ";")
[_ _ token] (&reader/read-regex +ident-re+)]
(return (&/T [meta (&/T ["lux" token])])))
)))
(def ^:private lex-symbol
(|do [[meta ident] lex-ident]
(return (&/T [meta ($Symbol ident)]))))
(def ^:private lex-tag
(|do [[meta _ _] (&reader/read-text "#")
[_ ident] lex-ident]
(return (&/T [meta ($Tag ident)]))))
(do-template [<name> <text> <tag>]
(def <name>
(|do [[meta _ _] (&reader/read-text <text>)]
(return (&/T [meta <tag>]))))
^:private lex-open-paren "(" $Open_Paren
^:private lex-close-paren ")" $Close_Paren
^:private lex-open-bracket "[" $Open_Bracket
^:private lex-close-bracket "]" $Close_Bracket
^:private lex-open-brace "{" $Open_Brace
^:private lex-close-brace "}" $Close_Brace
)
(def ^:private lex-delimiter
(&/try-all% (&/|list lex-open-paren
lex-close-paren
lex-open-bracket
lex-close-bracket
lex-open-brace
lex-close-brace)))
;; [Exports]
(def lex
(&/try-all-% "[Reader Error]"
(&/|list lex-white-space
lex-comment
lex-bool
lex-nat
lex-real
lex-frac
lex-int
lex-char
lex-text
lex-symbol
lex-tag
lex-delimiter)))
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