Add simple version

Does not "parse" any more structure than needed to get the coding C
from a (declare-file (coding C) ...) form. The coding must be the
first declaration inside the declare-file. This version does not check
that the rest of the declare-file form is valid.
This commit is contained in:
Lassi Kortela 2019-05-13 00:36:37 +03:00
parent d5ea8c21ec
commit 7f70dd8906
1 changed files with 61 additions and 0 deletions

View File

@ -0,0 +1,61 @@
(import (scheme base) (scheme char) (scheme file)
(scheme read) (scheme write))
(define (read-declarations-from-file filename)
(let ((bytes (let ((bytes (call-with-port
(open-binary-input-file filename)
(lambda (port) (read-bytevector 1000 port)))))
(if (eof-object? bytes) (make-bytevector 0) bytes)))
(i 0))
(define (peek-next-ascii-byte)
(if (not (< i (bytevector-length bytes)))
(eof-object)
(let ((next-byte (bytevector-u8-ref bytes i)))
(if (<= 1 next-byte 126)
next-byte
(begin (set! i (+ i 1))
(peek-next-ascii-byte))))))
(define (read-char? k)
(let* ((next-byte (peek-next-ascii-byte))
(next-char (if (eof-object? next-byte)
next-byte (integer->char next-byte)))
(consume? (cond ((procedure? k) (k next-char))
((char? k) (eqv? k next-char))
(else #f))))
(cond (consume? (set! i (+ i 1)) next-char)
(else #f))))
(define (read-char* k)
(let loop ((chars '()))
(let ((c (read-char? k)))
(if c (loop (append chars (list c)))
(if (null? chars) #f (list->string chars))))))
(define (symbol-char? c)
(not (or (eof-object? c) (char-whitespace? c)
(eqv? c #\") (eqv? c #\() (eqv? c #\)))))
(define (read->eol)
(read-char* (lambda (c) (not (eqv? c #\newline)))))
(define (skip-white-comm)
(cond ((read-char? #\;) (read->eol) (skip-white-comm))
((read-char* char-whitespace?) (skip-white-comm))
(else #f)))
(define (read-lexeme)
(skip-white-comm)
(cond ((read-char? #\()) ((read-char? #\))) ((read-char* symbol-char?))
(else #f)))
(let* ((shebang (and (read-char? #\#) (read-char? #\!) (read->eol))))
(cons shebang
(and (eqv? (read-lexeme) #\() (equal? (read-lexeme) "declare-file")
(eqv? (read-lexeme) #\() (equal? (read-lexeme) "coding")
(let ((coding (read-lexeme)))
(and (string? coding) (eqv? (read-lexeme) #\))
(string-downcase coding))))))))
(define (writeln x)
(write x)
(newline))
(writeln (read-declarations-from-file "test-big5.scm"))
(writeln (read-declarations-from-file "test-euc-jp.scm"))
(writeln (read-declarations-from-file "test-shift-jis.scm"))
(writeln (read-declarations-from-file "test-utf16-be.scm"))
(writeln (read-declarations-from-file "test-utf16-le.scm"))