Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
tree: 8ba922c739
Fetching contributors…

Cannot retrieve contributors at this time

136 lines (120 sloc) 6.234 kb
; Copyright (c) Richard Lyman. All rights reserved.
; The use and distribution terms for this software are covered by the
; Eclipse Public License 1.0 (http://www.eclipse.org/legal/epl-v10.html)
; which can be found in the file epl-v10.html at the root of this distribution.
; By using this software in any fashion, you are agreeing to be bound by
; the terms of this license.
; You must not remove this notice, or any other, from this software.
(ns com.lithinos.amotoen.core)
(declare pegasus)
(def ^:dynamic *currentK* (ref nil))
(defprotocol IPosition
(psdebug [t] "Some form of helpful debug info")
(in [t] "Indent - for debugging")
(de [t] "Dedent - for debugging")
(clone [t] "")
(gp [t] "Get pos") ; E.V.I.L. ... maybe
(sp [t j] "Set pos") ; E.V.I.L. ... maybe
(end [t] "End of input")
(m [t] "Returns the 'c' then (inc pos)")
(c [t] "The character at pos"))
(defn gen-ps
([s] (gen-ps s 0))
([s j]
(let [j (ref j)
indent (ref 0)]
(reify IPosition
(psdebug [t]
(let [indent-string (apply str (take @indent (repeat " ")))
padding (apply str (take 60 (repeat " ")))
x (str "'" (pr-str (try (subs s (max 0 (- @j 30)) (max 0 @j)) (catch Exception e ""))) "'")
y (str " " (pr-str (c t)) " ")
z (str "'" (pr-str (try (subs s (inc @j) (min (+ @j 30) (count s))) (catch Exception e ""))) "'")]
(str (subs (str (if (< @j 0) (str "<-" (subs s 0 20)) (str x y z)) padding) 0 60) indent-string)))
(in [t] (dosync (alter indent inc)))
(de [t] (dosync (alter indent dec)))
(gp [t] @j)
(sp [t k] (dosync (ref-set j k)))
(clone [t] (gen-ps s @j))
(end [t] (= @j (count s)))
(m [t] (let [r (c t)] (dosync (alter j inc)) r))
(c [t] (try (.charAt s @j) (catch Exception e nil)))))))
(defn lpegs [t s] (reverse (into '() (cons t (seq s))))) ; This doesn't need to be fast, but shouldn't the following work? (list (cons t (seq s)))
(defn pegs [s] (vec (seq s)))
(def ^:dynamic *debug* (ref false))
(defn- debug [w & args] (when @*debug* (print (psdebug w)) (print @*currentK* " ") (apply println args) (flush)))
(def #^{:private true} grammar-grammar {
:Whitespace '(| \space \newline \tab \,)
:_* '(* :Whitespace)
:_ [:Whitespace '(* :Whitespace)]
:Grammar [\{ :_* :Rule '(* [:_ :Rule]) :_* \}]
:Rule [:Keyword :_ :Body]
:Keyword [\: :ValidKeywordChar '(* :ValidKeywordChar)]
:Body '(| :Keyword :Char :Grouping)
:Grouping '(| :Sequence :Either :ZeroOrMore :AnyNot)
:Sequence [\[ :_* :Body '(* [:_* :Body]) :_* \]]
:Either [\( \| :_ :Body '(* [:_* :Body]) :_* \)]
:ZeroOrMore [\( \* :_ :Body :_* \)]
:AnyNot [\( \% :_ :Body :_* \)]
:Char [\\ (list '| (pegs "tab") (pegs "space") (pegs "newline") '(% \space))]
:ValidKeywordChar (lpegs '| "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789:/*+!_?-")
})
(defn- either [n g w] (let [original (gp w)] (first (keep #(do (sp w original) (pegasus % g w)) (rest n)))))
(defn- any-not [b g w]
(let [c (c w) p (gp w)]
(if (pegasus b g w)
(do (sp w p) nil) ; If we succeed, then we fail - that's the point of AnyNot... and rollback
(do (debug w "AnyNot MATCH:" (pr-str b) c) (m w) c)))); If we fail, then we accept the current char
(defn- typed-list [n g w]
(let [t (first n)
b (second n)
result (cond (= t '|) (let [temp (either n g w)] #_(debug w "Either returning:" (pr-str temp)) temp)
(= t '%) (any-not b g w)
(= t '*) (doall (take-while #(if (keyword? b) (b %) %)
(repeatedly #(pegasus b g w)))))]
(if (and (seq? result) (= 1 (count result)))
(first result)
result)))
(defn- try-char [n w]
(if (= n (c w))
(do (debug w (str "MATCH: '" (pr-str n) "' with '" (pr-str (c w)) "'"))
(m w))
(do #_(debug w (str "FAIL: '" (pr-str n) "' with '" (pr-str (c w)) "'"))
nil)))
(defn- peg-vec [n g w]
(loop [remaining n
result []]
(if (empty? remaining)
result
(let [temp (pegasus (first remaining) g w)]
(if temp (recur (rest remaining)
(conj result temp)))))))
(defn- p [w s n] (debug w s (pr-str n)))
; Accept a 'debug limit' - if 0 then always dump everything. If more than 0, only keep limit number of lines of debug and print out at end
(defn pegasus [n g w]
(in w)
(when (keyword? n) (dosync (ref-set *currentK* n)))
(let [result (cond
(keyword? n)(do (p w "k:" n) (let [temp (pegasus (n g) g w)] (if temp {n temp} nil)))
(vector? n) (do #_(p w "v:" n) (peg-vec n g w))
(list? n) (do #_(p w "l:" n) (typed-list n g w))
(char? n) (do #_(p w "c:" n) (try-char n w))
true (throw (Error. (str "Unknown type: " n))))]
(when (keyword? n) (dosync (ref-set *currentK* n)))
(de w)
result))
; If pegasus is given a keyword, but it doesn't exist in the given grammar, a useful error should be thrown
(defn validate ([g] (validate g false))
([g d]
(dosync (ref-set *debug* d))
(let [w (gen-ps (pr-str g))]
(if (or (nil? (pegasus :Grammar grammar-grammar w))
(not (end w)))
(println "Fail")
(println "Pass")))
(dosync (ref-set *debug* false))))
(defn self-check [] (validate grammar-grammar))
; TODO
;
; When processing the elements of a vector - the keyword needs to return to whatever it was each time an element is processed...
;
Jump to Line
Something went wrong with that request. Please try again.