pull/21/head
Matthew Butterick 6 years ago
parent ac5daac9ea
commit 0a0d5831a7

@ -2,5 +2,5 @@
top : (fun | app)*
fun : /"fun" ID /"(" ID [/"," ID] /")" /"=" expr
expr : ID "+" ID | app
expr : ID /"+" ID | app
app : ID /"(" (ID | INT) [/"," ID] /")"

@ -9,7 +9,7 @@
(:or "fun" "(" ")" "=" "+" ","))
(define tokenize-1
(lexer
(lexer-srcloc
[whitespace (token lexeme #:skip? #t)]
[(from/stop-before "#" "\n") (token 'COMMENT #:skip? #t)]
[reserved-toks lexeme]
@ -23,12 +23,13 @@
[(_ VAR ARG0 ARG1 EXPR) #'(define (VAR ARG0 ARG1) EXPR)])
(define-macro-cases expr
[(_ LEFT "+" RIGHT) #'(+ LEFT RIGHT)]
[(_ LEFT RIGHT) #'(+ LEFT RIGHT)]
[(_ OTHER) #'OTHER])
(define-macro app #'#%app)
(define (read-syntax src ip)
(port-count-lines! ip)
(define parse-tree (parse src (λ () (tokenize-1 ip))))
(strip-bindings
(with-syntax ([PT parse-tree])

@ -3,9 +3,9 @@
top : (fun | app)*
fun : /"fun" var /"(" argvars /")" /"=" expr
/argvars : [var (/"," var)*]
@expr : s-or-d
s-or-d : [s-or-d ("+" | "-")] p-or-q
p-or-q : [p-or-q ("*" | "/")] value
@expr : add-or-sub
add-or-sub : [add-or-sub ("+" | "-")] mult-or-div
mult-or-div : [mult-or-div ("*" | "/")] value
@value : var | INT | app | /"(" expr /")"
app : var /"(" [expr (/"," expr)*] /")"
@var : ID

@ -1,6 +1,6 @@
#lang br/quicklang
(require brag/support "grammar.rkt")
(provide top fun app s-or-d p-or-q)
(provide top fun app add-or-sub mult-or-div)
(module+ reader
(provide read-syntax))
@ -16,20 +16,23 @@
[(:or (from/stop-before "#" "\n")
(from/to "/*" "*/")) (token 'COMMENT #:skip? #t)]
[reserved-toks lexeme]
[(:seq alphabetic (:* (:or alphabetic) digits)) (token 'ID (string->symbol lexeme))]
[(:seq (:? "-") (:+ digits)) (token 'INT (string->number lexeme))]))
[(:seq (:? "-") (:+ (:or alphabetic) digits))
(let ([maybe-num (string->number lexeme)])
(if maybe-num
(token 'INT maybe-num)
(token 'ID (string->symbol lexeme))))]))
(define-macro top #'#%module-begin)
(define-macro (fun VAR (ARGVAR ...) EXPR)
#'(define (VAR ARGVAR ...) EXPR))
(define-macro-cases s-or-d
(define-macro-cases add-or-sub
[(_ LEFT "+" RIGHT) #'(+ LEFT RIGHT)]
[(_ LEFT "-" RIGHT) #'(- LEFT RIGHT)]
[(_ OTHER) #'OTHER])
(define-macro-cases p-or-q
(define-macro-cases mult-or-div
[(_ LEFT "*" RIGHT) #'(* LEFT RIGHT)]
[(_ LEFT "/" RIGHT) #'(/ LEFT RIGHT)]
[(_ OTHER) #'OTHER])
@ -37,6 +40,7 @@
(define-macro app #'#%app)
(define (read-syntax src ip)
(port-count-lines! ip)
(define parse-tree (parse src (λ () (tokenize-1 ip))))
(strip-bindings
(with-syntax ([PT parse-tree])

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