108 lines
3.3 KiB
Scheme
108 lines
3.3 KiB
Scheme
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(define-module (potato parse)
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#:use-module (srfi srfi-1)
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#:use-module (ice-9 receive)
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#:use-module (system vm trace)
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#:use-module (potato exceptions)
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#:use-module (potato makevars)
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#:use-module (potato rules)
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#:use-module (potato text)
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#:use-module (potato parse-lib)
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#:export (parse _readline))
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;; A makefile can contain rules, macro definitions, include lines,
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;; and comments.
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(define (parse filename)
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(with-input-from-file filename _eval #:guess-encoding #t))
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(define (_eval)
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(let ((filenames #f)
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(ignoring #f)
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(commands '()))
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(while #t
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(receive (line nlines)
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(read-line-handle-escaped-newline)
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(cond
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((zero? nlines)
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(break))
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((string-starts-with? line #\tab)
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;; Shell-command lines
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(when filenames
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(when ignoring
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(continue))
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(set! commands (append commands (list line)))))
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(else
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(display
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(string-trim-both
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(string-remove-comments
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(string-collapse-continuations line #t))))
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(newline)))))))
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(define (string-parse-variable-definition str i)
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"Parse a string as a variable definition."
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(let loop ((i (string-next-token str)))
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(cond
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((= i (string-length str))
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(values i 'null))
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((char=? (string-ref str i) #\#)
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;; Comments aren't variable definitions.
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(values i 'null))
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((char=? (string-ref str i) #\$)
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;; This begins a variable expansion reference.
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(let* ((openparen (false-if-exception (string-ref str (1+ i))))
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(closeparen (if (eqv? openparen #\()
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#\)
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(if (eqv? openparen #\{)
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#\}
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#f))))
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(if (not closeparen)
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(values i 'null)
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;; else, skip over the matching closeparen
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(begin
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(let ((count 0))
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(while #t
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(set! i (1+ i))
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(when (char=? (string-ref str i) openparen)
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(set! count (1+ count)))
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(when (char=? (string-ref str i) closeparen)
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(set! count (1- count))
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(when (zero? count)
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(set! i (1+ i))
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(break)))))
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;; Any whitespace before the operator?
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(when (char-set-contains? char-set:blank (string-ref str i))
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(set! wspace #t)
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(set! i (string-next-token str i)))
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(cond
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((eqv? (string-ref str i) #\=)
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(values (1+ i) 'recursive))
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((and (eqv? (string-ref str i) #\:)
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(eqv? (string-ref str (1+ i)) #\=))
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(values (+ i 2) 'simple))
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((and (eqv? (string-ref str i) #\+)
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(eqv? (string-ref str (1+ i)) #\=))
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(values (+ i 2) 'append))
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((and (eqv? (string-ref str i) #\?)
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(eqv? (string-ref str (1+ i)) #\=))
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(values (+ i 2) 'conditional))
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(else
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(values i 'null)))))))
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(else
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(values i 'null)))))
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#|
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(define (parse-var-assignment line)
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(let ((i (string-next-token line 0)))
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(if (= i (string-length line))
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#f
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;; else
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(while #t
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|#
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