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builtins: Support \non-builtin escape. 

* gash/peg.scm (builtin): Add #:prefer-builtin? keyword argument.
  (transform): Support \non-builtin escape.
This commit is contained in:
Jan Nieuwenhuizen 2018-07-14 15:57:02 +02:00
parent e5c6324d82
commit e0169d0acd
1 changed files with 9 additions and 5 deletions
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14
gash/peg.scm
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@ -261,10 +261,15 @@
(('substitution o) `(substitution ,@(transform o)))
(('pipeline o) (pk `(pipeline ,(transform o))))
(('pipeline h t) (pk `(pipeline ,(transform h) ,@(map transform t))))
(('command o ...) (let ((command (map transform o)))
(('command o ...) (let* ((command (map transform o))
(program (car command))
(escape-builtin? (string-prefix? "\\" program))
(program (if escape-builtin? (string-drop program 1) program))
(command (cons program (cdr command))))
(when (> %debug-level 1)
(format (current-error-port) "transform command=~s\n" command))
(or (builtin command)
(or (builtin command #:prefer-builtin? (and %prefer-builtins?
(not escape-builtin?)))
`(command ,@command))))
(('literal o) (transform o))
(('name o) o)
@ -278,7 +283,7 @@
(('else-part o ...) `(begin ,@(map transform o)))
(_ ast)))
(define (builtin ast)
(define* (builtin ast #:key prefer-builtin?)
;; FIXME: distinguish between POSIX compliant builtins and
;; `best-effort'/`fallback'?
"Possibly modify command to use a builtin."
@ -289,11 +294,10 @@
(((and (? string?) command) args ...) (values command args))
(_ (values #f #f)))
(let ((program (and command
(not %prefer-builtins?)
(PATH-search-path command))))
(when (> %debug-level 0)
(format (current-error-port) "command ~a => ~s ~s\n" (or program 'builtin) command args))
(cond (program #f)
(cond ((and program (not prefer-builtin?)) #f)
((and command (assoc-ref %builtin-commands command))
=>
(lambda (command)