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Rx documentation touch-ups (bug#46910)

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* doc/lispref/searching.texi (Rx Constructs, Rx Functions):
Add clarifications and improve naming of arguments.  Add examples
illustrating the differences between `rx` and `rx-to-string`.
This commit is contained in:
Mattias Engdegård 2021-09-26 14:36:02 +02:00
parent c51b1c02db
commit 6e1de14e51
1 changed files with 24 additions and 6 deletions
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doc/lispref/searching.texi
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@ -1060,7 +1060,8 @@ customization.
The various forms in @code{rx} regexps are described below. The
shorthand @var{rx} represents any @code{rx} form, and @var{rx}@dots{}
means zero or more @code{rx} forms. Where the corresponding string
means zero or more @code{rx} forms. These are all valid arguments to
the @code{rx} macro. Where the corresponding string
regexp syntax is given, @var{A}, @var{B}, @dots{} are string regexp
subexpressions.
@ -1356,7 +1357,8 @@ names:
For details, @pxref{Syntax Class Table}. Please note that
@code{(syntax punctuation)} is @emph{not} equivalent to the character class
@code{punctuation}.@*
Corresponding string regexp: @samp{\s@var{code}}
Corresponding string regexp: @samp{\s@var{char}} where @var{char} is the
syntax character.
@item @code{(category @var{category})}
@cindex @code{category} in rx
@ -1413,7 +1415,8 @@ the names below or its category character.
For more information about currently defined categories, run the
command @kbd{M-x describe-categories @key{RET}}. For how to define
new categories, @pxref{Categories}.@*
Corresponding string regexp: @samp{\c@var{code}}
Corresponding string regexp: @samp{\c@var{char}} where @var{char} is the
category character.
@end table
@subsubheading Zero-width assertions
@ -1543,11 +1546,18 @@ in the current global environment.
@node Rx Functions
@subsubsection Functions and macros using @code{rx} regexps
@defmac rx rx-expr@dots{}
Translate the @var{rx-expr}s to a string regexp, as if they were the
@defmac rx rx-form@dots{}
Translate the @var{rx-form}s to a string regexp, as if they were the
body of a @code{(seq @dots{})} form. The @code{rx} macro expands to a
string constant, or, if @code{literal} or @code{regexp} forms are
used, a Lisp expression that evaluates to a string.
used, a Lisp expression that evaluates to a string. Example:
@example
@group
(rx (+ alpha) "=" (+ digit))
@result{} "[[:alpha:]]+=[[:digit:]]+"
@end group
@end example
@end defmac
@defun rx-to-string rx-expr &optional no-group
@ -1555,6 +1565,14 @@ Translate @var{rx-expr} to a string regexp which is returned.
If @var{no-group} is absent or nil, bracket the result in a
non-capturing group, @samp{\(?:@dots{}\)}, if necessary to ensure that
a postfix operator appended to it will apply to the whole expression.
Example:
@example
@group
(rx-to-string '(seq (+ alpha) "=" (+ digit)) t)
@result{} "[[:alpha:]]+=[[:digit:]]+"
@end group
@end example
Arguments to @code{literal} and @code{regexp} forms in @var{rx-expr}
must be string literals.