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more readtable customization

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svn: r6924

original commit: 67941597640f6cd2805b92b5895d89896ca9d8f7
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Eli Barzilay 2007-07-16 16:55:12 +00:00
parent fb3077b79f
commit b1e8c2cace
1 changed files with 56 additions and 15 deletions
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collects/scribble/doc.txt
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@ -645,25 +645,66 @@ in reading.
> (read-inside [input-port])
> (read-inside-syntax [source-name] [input-port])
These `-inner' variants parse as if starting inside a "@{...}", and
These `-inside' variants parse as if starting inside a "@{...}", and
they return a (syntactic) list. Useful for implementing languages
that are textual by default (see "docreader.ss" for example).
> (make-at-readtable [readtable])
> (make-at-readtable [keyword-args...])
Constructs an @-readtable, based on the input argument if given, or
`current-readtable' otherwise.
Constructs an @-readtable. The keyword arguments can customize the
resulting reader in several ways.
> (use-at-readtable)
* #:readtable -- a readtable to base the @-readtable on. Defaults to
the current readtable.
* #:command-char -- the character used for @-forms; defaults to `#\@'.
* #:datum-readtable -- determines the readtable used for reading the
datum part. The default (#t) is to use the @-readtable, otherwise
it can be a readtable, or a readtable-to-readtable function that
will construct one from the @-readtable. The idea is that you may
want to have completely different uses for the datum part, for
example, introducing an easy syntax for `key=val' attributes.
* #:syntax-post-processor -- a function that is applied on each
resulting syntax value after it has been parsed (but before it is
wrapped quoting punctuations). You can use this to further control
uses of @-forms, for example, making the command be the head of a
list:
(use-at-readtable
#:syntax-post-processor
(lambda (stx)
(syntax-case stx ()
[(cmd rest ...) #'(list 'cmd rest ...)]
[_else (error "@ forms must have a body")])))
Beware that the syntax may contain placeholder values at this stage
(e.g: the command part), so you can `plant' your own form that will
do some plain processing later. For example, here's a setup that
uses a `mk-' prefix for all command names:
(use-at-readtable
#:syntax-post-processor
(lambda (stx)
(syntax-case stx ()
[(cmd rest ...) #'(add-mk cmd rest ...)]
[_else (error "@ forms must have a body")])))
(define-syntax (add-mk stx)
(syntax-case stx ()
[(_ cmd rest ...)
(identifier? #'cmd)
(with-syntax ([mk-cmd (datum->syntax-object
#'cmd
(string->symbol
(format "mk-~a" (syntax-e #'cmd)))
#'cmd)])
(syntax/loc stx (mk-cmd rest ...)))]))
* #:start-inside? -- used internally by the above `-inside' variants.
> (use-at-readtable [keyword-args])
Installs the Scribble readtable as the default. Useful for REPL
experimentation. (Note: enables line and column tracking.)
> datum-readtable
A parameter that determines the readtable used for reading the datum
part. The default (#t) is to use the current readtable (usually a
result of `make-at-readtable'), otherwise it can be a readtable, or a
readtable-to-readtable function that will construct one. (The idea is
that you may want to have completely different uses for the datum
part.)
experimentation. (Note: enables line and column tracking.) The given
keyword arguments are used with `make-at-readtable'.