You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
96 lines
3.0 KiB
Racket
96 lines
3.0 KiB
Racket
7 years ago
|
#lang br/quicklang
|
||
|
|
(require "grammar.rkt" brag/support racket/pretty racket/stxparam)
|
||
|
|
(provide (except-out (all-from-out br/quicklang) for if print) (all-defined-out) pretty-print)
|
||
|
|
|
||
|
|
(module+ reader
|
||
|
|
(provide read-syntax))
|
||
|
|
|
||
|
|
(define-lex-abbrev reserved-terms
|
||
|
|
(:or "=" "def" "(" ")" ":" ","
|
||
|
|
"return" "for" "in"
|
||
|
|
"+" "-" "*" "/" "<" ">" "\""
|
||
|
|
"if" "else" "print"))
|
||
|
|
(define-lex-abbrev indent (:: (:+ "\n") (:* " ")))
|
||
|
|
|
||
|
|
(define prev-indent 0)
|
||
|
|
(define pending-dedents 0)
|
||
|
|
|
||
|
|
(define (lex ip)
|
||
|
|
(define inner-lex
|
||
|
|
(lexer
|
||
|
|
[(eof) (cond
|
||
|
|
[(> prev-indent 0)
|
||
|
|
(set! pending-dedents prev-indent)
|
||
|
|
(set! prev-indent 0)
|
||
|
|
(lex input-port)]
|
||
|
|
[else eof])]
|
||
|
|
[(from/stop-before "#" "\n") (token 'COMMENT #:skip? #t)]
|
||
|
|
[indent
|
||
|
|
(match-let* ([(list _ spaces) (regexp-match #rx"^\n+( *)$" lexeme)]
|
||
|
|
[this-indent (/ (string-length spaces) 2)])
|
||
|
|
(define tok
|
||
|
|
(cond
|
||
|
|
[(> (- this-indent prev-indent) 1) (error 'only-one-indent-please)]
|
||
|
|
[(> this-indent prev-indent) (token 'INDENT)]
|
||
|
|
[(< this-indent prev-indent)
|
||
|
|
(set! pending-dedents (- prev-indent this-indent))
|
||
|
|
(lex input-port)]
|
||
|
|
[(= this-indent prev-indent) (token lexeme #:skip? #t)]))
|
||
|
|
(set! prev-indent this-indent)
|
||
|
|
tok)]
|
||
|
|
[(:+ whitespace) (token lexeme #:skip? #t)]
|
||
|
|
[reserved-terms (token lexeme (string->symbol lexeme))]
|
||
|
|
[(:+ (:- (:or alphabetic punctuation) reserved-terms))
|
||
|
|
(token 'ID (string->symbol lexeme))]
|
||
|
|
[(:+ (char-set "0123456789"))
|
||
|
|
(token 'INTEGER (string->number lexeme))]))
|
||
|
|
(cond
|
||
|
|
[(equal? (peek-char ip) #\") (token 'STRING (read ip))]
|
||
|
|
[(> pending-dedents 0)
|
||
|
|
(set! pending-dedents (sub1 pending-dedents))
|
||
|
|
(token 'DEDENT)]
|
||
|
|
[else (inner-lex ip)]))
|
||
|
|
|
||
|
|
(define-macro top #'begin)
|
||
|
|
(define-macro (assignment ID EXPR)
|
||
|
|
#'(define ID EXPR))
|
||
|
|
|
||
|
|
(define-macro-cases comparison
|
||
|
|
[(_ ARG) #'ARG]
|
||
|
|
[(_ LARG OP RARG) #'(OP LARG RARG)])
|
||
|
|
|
||
|
|
(define-macro sum #'comparison)
|
||
|
|
(define-macro product #'comparison)
|
||
|
|
|
||
|
|
(define-macro (func-def ID ID-ARGS STMT ...)
|
||
|
|
#'(define (ID . ID-ARGS)
|
||
|
|
(let/cc return-cc
|
||
|
|
(syntax-parameterize ([return (make-rename-transformer #'return-cc)])
|
||
|
|
STMT ... (void)))))
|
||
|
|
|
||
|
|
(define-syntax-parameter return (λ (stx) (error 'not-parameterized)))
|
||
|
|
(define-macro func-app #'#%app)
|
||
|
|
|
||
|
|
(provide (rename-out [my-for for]))
|
||
|
|
(define-macro (my-for ID EXPR . STMTS)
|
||
|
|
#'(for ([ID (in-list EXPR)])
|
||
|
|
. STMTS))
|
||
|
|
|
||
|
|
(define-macro block #'begin)
|
||
|
|
|
||
|
|
(provide (rename-out [my-if if]))
|
||
|
|
(define-macro-cases my-if
|
||
|
|
[(_ COND TBLOCK) #'(when COND TRUE-BLOCK)]
|
||
|
|
[(_ COND TBLOCK FBLOCK) #'(if COND (let () TBLOCK) (let () FBLOCK))])
|
||
|
|
|
||
|
|
(provide (rename-out [my-print print]))
|
||
|
|
(define-macro (my-print EXPR)
|
||
|
|
#'(display EXPR))
|
||
|
|
|
||
|
|
(define (read-syntax src ip)
|
||
|
|
(define parse-tree (parse (λ () (lex ip))))
|
||
|
|
(strip-context
|
||
|
|
(with-syntax ([PT parse-tree])
|
||
|
|
#'(module _ pythonesque-demo
|
||
|
|
#;(pretty-print 'PT)
|
||
|
|
PT))))
|