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;;; srfi-37.scm --- args-fold |
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;; Copyright (C) 2007, 2008, 2013 Free Software Foundation, Inc. |
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;; |
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;; This library is free software; you can redistribute it and/or |
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;; modify it under the terms of the GNU Lesser General Public |
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;; License as published by the Free Software Foundation; either |
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;; version 3 of the License, or (at your option) any later version. |
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;; |
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;; This library is distributed in the hope that it will be useful, |
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of |
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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;; Lesser General Public License for more details. |
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;; |
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;; You should have received a copy of the GNU Lesser General Public |
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;; License along with this library; if not, write to the Free Software |
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;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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;;; Commentary: |
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;; |
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;; To use this module with Guile, use (cdr (program-arguments)) as |
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;; the ARGS argument to `args-fold'. Here is a short example: |
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;; |
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;; (args-fold (cdr (program-arguments)) |
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;; (let ((display-and-exit-proc |
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;; (lambda (msg) |
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;; (lambda (opt name arg) |
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;; (display msg) (quit) (values))))) |
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;; (list (option '(#\v "version") #f #f |
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;; (display-and-exit-proc "Foo version 42.0\n")) |
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;; (option '(#\h "help") #f #f |
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;; (display-and-exit-proc |
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;; "Usage: foo scheme-file ...")))) |
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;; (lambda (opt name arg) |
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;; (error "Unrecognized option `~A'" name)) |
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;; (lambda (op) (load op) (values))) |
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;; |
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;;; Code: |
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;;;; Module definition & exports |
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(define-module (srfi srfi-37) |
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#:use-module (srfi srfi-9) |
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#:export (option option-names option-required-arg? |
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option-optional-arg? option-processor |
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args-fold)) |
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(cond-expand-provide (current-module) '(srfi-37)) |
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;;;; args-fold and periphery procedures |
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;;; An option as answered by `option'. `names' is a list of |
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;;; characters and strings, representing associated short-options and |
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;;; long-options respectively that should use this option's |
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;;; `processor' in an `args-fold' call. |
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;;; |
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;;; `required-arg?' and `optional-arg?' are mutually exclusive |
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;;; booleans and indicate whether an argument must be or may be |
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;;; provided. Besides the obvious, this affects semantics of |
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;;; short-options, as short-options with a required or optional |
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;;; argument cannot be followed by other short options in the same |
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;;; program-arguments string, as they will be interpreted collectively |
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;;; as the option's argument. |
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;;; |
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;;; `processor' is called when this option is encountered. It should |
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;;; accept the containing option, the element of `names' (by `equal?') |
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;;; encountered, the option's argument (or #f if none), and the seeds |
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;;; as variadic arguments, answering the new seeds as values. |
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(define-record-type srfi-37:option |
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(option names required-arg? optional-arg? processor) |
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option? |
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(names option-names) |
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(required-arg? option-required-arg?) |
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(optional-arg? option-optional-arg?) |
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(processor option-processor)) |
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(define (error-duplicate-option option-name) |
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(scm-error 'program-error "args-fold" |
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"Duplicate option name `~A~A'" |
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(list (if (char? option-name) #\- "--") |
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option-name) |
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#f)) |
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(define (build-options-lookup options) |
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"Answer an `equal?' Guile hash-table that maps OPTIONS' names back |
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to the containing options, signalling an error if a name is |
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encountered more than once." |
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(let ((lookup (make-hash-table (* 2 (length options))))) |
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(for-each |
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(lambda (opt) |
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(for-each (lambda (name) |
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(let ((assoc (hash-create-handle! |
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lookup name #f))) |
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(if (cdr assoc) |
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(error-duplicate-option (car assoc)) |
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(set-cdr! assoc opt)))) |
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(option-names opt))) |
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options) |
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lookup)) |
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(define (args-fold args options unrecognized-option-proc |
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operand-proc . seeds) |
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"Answer the results of folding SEEDS as multiple values against the |
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program-arguments in ARGS, as decided by the OPTIONS' |
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`option-processor's, UNRECOGNIZED-OPTION-PROC, and OPERAND-PROC." |
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(let ((lookup (build-options-lookup options))) |
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;; I don't like Guile's `error' here |
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(define (error msg . args) |
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(scm-error 'misc-error "args-fold" msg args #f)) |
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(define (mutate-seeds! procedure . params) |
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(set! seeds (call-with-values |
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(lambda () |
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(apply procedure (append params seeds))) |
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list))) |
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;; Clean up the rest of ARGS, assuming they're all operands. |
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(define (rest-operands) |
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(for-each (lambda (arg) (mutate-seeds! operand-proc arg)) |
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args) |
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(set! args '())) |
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;; Call OPT's processor with OPT, NAME, an argument to be decided, |
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;; and the seeds. Depending on OPT's *-arg? specification, get |
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;; the parameter by calling REQ-ARG-PROC or OPT-ARG-PROC thunks; |
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;; if no argument is allowed, call NO-ARG-PROC thunk. |
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(define (invoke-option-processor |
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opt name req-arg-proc opt-arg-proc no-arg-proc) |
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(mutate-seeds! |
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(option-processor opt) opt name |
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(cond ((option-required-arg? opt) (req-arg-proc)) |
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((option-optional-arg? opt) (opt-arg-proc)) |
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(else (no-arg-proc) #f)))) |
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;; Compute and answer a short option argument, advancing ARGS as |
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;; necessary, for the short option whose character is at POSITION |
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;; in the current ARG. |
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(define (short-option-argument position) |
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(cond ((< (1+ position) (string-length (car args))) |
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(let ((result (substring (car args) (1+ position)))) |
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(set! args (cdr args)) |
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result)) |
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((pair? (cdr args)) |
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(let ((result (cadr args))) |
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(set! args (cddr args)) |
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result)) |
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((pair? args) |
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(set! args (cdr args)) |
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#f) |
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(else #f))) |
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;; Interpret the short-option at index POSITION in (car ARGS), |
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;; followed by the remaining short options in (car ARGS). |
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(define (short-option position) |
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(if (>= position (string-length (car args))) |
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(begin |
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(set! args (cdr args)) |
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(next-arg)) |
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(let* ((opt-name (string-ref (car args) position)) |
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(option-here (hash-ref lookup opt-name))) |
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(cond ((not option-here) |
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(mutate-seeds! unrecognized-option-proc |
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(option (list opt-name) #f #f |
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unrecognized-option-proc) |
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opt-name #f) |
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(short-option (1+ position))) |
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(else |
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(invoke-option-processor |
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option-here opt-name |
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(lambda () |
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(or (short-option-argument position) |
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(error "Missing required argument after `-~A'" opt-name))) |
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(lambda () |
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;; edge case: -xo -zf or -xo -- where opt-name=#\o |
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;; GNU getopt_long resolves these like I do |
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(short-option-argument position)) |
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(lambda () #f)) |
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(if (not (or (option-required-arg? option-here) |
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(option-optional-arg? option-here))) |
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(short-option (1+ position)))))))) |
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;; Process the long option in (car ARGS). We make the |
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;; interesting, possibly non-standard assumption that long option |
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;; names might contain #\=, so keep looking for more #\= in (car |
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;; ARGS) until we find a named option in lookup. |
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(define (long-option) |
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(let ((arg (car args))) |
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(let place-=-after ((start-pos 2)) |
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(let* ((index (string-index arg #\= start-pos)) |
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(opt-name (substring arg 2 (or index (string-length arg)))) |
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(option-here (hash-ref lookup opt-name))) |
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(if (not option-here) |
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;; look for a later #\=, unless there can't be one |
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(if index |
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(place-=-after (1+ index)) |
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(mutate-seeds! |
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unrecognized-option-proc |
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(option (list opt-name) #f #f unrecognized-option-proc) |
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opt-name #f)) |
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(invoke-option-processor |
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option-here opt-name |
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(lambda () |
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(if index |
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(substring arg (1+ index)) |
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(error "Missing required argument after `--~A'" opt-name))) |
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(lambda () (and index (substring arg (1+ index)))) |
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(lambda () |
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(if index |
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(error "Extraneous argument after `--~A'" opt-name)))))))) |
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(set! args (cdr args))) |
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;; Process the remaining in ARGS. Basically like calling |
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;; `args-fold', but without having to regenerate `lookup' and the |
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;; funcs above. |
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(define (next-arg) |
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(if (null? args) |
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(apply values seeds) |
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(let ((arg (car args))) |
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(cond ((or (not (char=? #\- (string-ref arg 0))) |
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(= 1 (string-length arg))) ;"-" |
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(mutate-seeds! operand-proc arg) |
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(set! args (cdr args))) |
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((char=? #\- (string-ref arg 1)) |
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(if (= 2 (string-length arg)) ;"--" |
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(begin (set! args (cdr args)) (rest-operands)) |
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(long-option))) |
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(else (short-option 1))) |
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(next-arg)))) |
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(next-arg))) |
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;;; srfi-37.scm ends here |