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According to Eric Blake on 12/21/2006 7:15 AM:
>
> Still more progress. The regexp tests are beefed up to catch more
> regression scenarios.
Also substr and patsubst.
2006-12-27 Eric Blake <[EMAIL PROTECTED]>
* doc/m4.texinfo (Substr, Patsubst): Merge more sections from the
branch.
* modules/m4.c (substr): Merge from branch.
- --
Life is short - so eat dessert first!
Eric Blake [EMAIL PROTECTED]
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Index: doc/m4.texinfo
===================================================================
RCS file: /sources/m4/m4/doc/m4.texinfo,v
retrieving revision 1.86
diff -u -p -r1.86 m4.texinfo
--- doc/m4.texinfo 26 Dec 2006 21:05:53 -0000 1.86
+++ doc/m4.texinfo 27 Dec 2006 14:12:17 -0000
@@ -5269,7 +5269,7 @@ Expands to the index of the first occurr
@var{substring} does not occur in @var{string}, @code{index} expands to
@samp{-1}.
-The builtin macro @code{index} is recognized only when given arguments.
+The macro @code{index} is recognized only with parameters.
@end deffn
@example
@@ -5392,21 +5392,36 @@ regexp(`GNUs not Unix', `\w\(\w+\)$', `P
@cindex extracting substrings
@cindex substrings, extracting
+Substrings are extracted with @code{substr}:
+
@deffn {Builtin (m4)} substr (@var{string}, @var{from}, @ovar{length})
-Substrings are extracted with @code{substr}, which expands to the
-substring of @var{string}, which starts at index @var{from}, and extends
-for @var{length} characters, or to the end of @var{string}, if
[EMAIL PROTECTED] is omitted. The starting index of a string is always 0.
+Expands to the substring of @var{string}, which starts at index
[EMAIL PROTECTED], and extends for @var{length} characters, or to the end of
[EMAIL PROTECTED], if @var{length} is omitted. The starting index of a
+is always 0. The expansion is empty if there is an error parsing
[EMAIL PROTECTED] or @var{length}, if @var{from} is beyond the end of
[EMAIL PROTECTED], or if @var{length} is negative.
+
+The macro @code{substr} is recognized only with parameters.
[EMAIL PROTECTED] deffn
@example
-substr(`gnus, gnats, and armadillos', 6)
+substr(`gnus, gnats, and armadillos', `6')
@result{}gnats, and armadillos
-substr(`gnus, gnats, and armadillos', 6, 5)
+substr(`gnus, gnats, and armadillos', `6', `5')
@result{}gnats
@end example
-The builtin macro @code{substr} is recognized only when given arguments.
[EMAIL PROTECTED] deffn
+Omitting @var{from} evokes a warning, but still produces output.
+
[EMAIL PROTECTED]
+substr(`abc')
[EMAIL PROTECTED]:stdin:1: Warning: substr: too few arguments: 1 < 2
[EMAIL PROTECTED]
+substr(`abc',)
[EMAIL PROTECTED]:stdin:2: Warning: substr: empty string treated as 0
[EMAIL PROTECTED]
[EMAIL PROTECTED] example
@node Translit
@section Translating characters
@@ -5415,7 +5430,7 @@ The builtin macro @code{substr} is recog
@cindex characters, translating
Character translation is done with @code{translit}:
[EMAIL PROTECTED] {Builtin (m4)} translit (@var{string}, @var{chars},
@var{replacement})
[EMAIL PROTECTED] {Builtin (m4)} translit (@var{string}, @var{chars},
@ovar{replacement})
Expands to @var{string}, with each character that occurs in
@var{chars} translated into the character from @var{replacement} with
the same index.
@@ -5481,17 +5496,20 @@ translit(`abc')
@cindex regular expressions
@cindex pattern substitution
@cindex substitution by regular expression
[EMAIL PROTECTED] GNU extensions
[EMAIL PROTECTED] @acronym{GNU} extensions
+Global substitution in a string is done by @code{patsubst}:
+
@deffn {Builtin (gnu)} patsubst (@var{string}, @var{regexp}, @
@ovar{replacement}, @ovar{resyntax})
-Global substitution in a string is done by @code{patsubst}, which
-searches @var{string} for matches of @var{regexp}, and substitutes
+Searches @var{string} for matches of @var{regexp}, and substitutes
@var{replacement} for each match.
-If @var{resyntax} is given, the particular flavor of regular
-expression understood with respect to @var{regexp} can be changed from
-the current default. @xref{Changeresyntax}, for details of the values
-that can be given for this parameter.
+If @var{resyntax} is given, the particular flavor of regular expression
+understood with respect to @var{regexp} can be changed from the current
+default. @xref{Changeresyntax}, for details of the values that can be
+given for this argument. Unlike @var{regexp}, if exactly three
+arguments given, the third argument is always treated as
[EMAIL PROTECTED], even if it matches a known syntax name.
The parts of @var{string} that are not covered by any match of
@var{regexp} are copied to the expansion. Whenever a match is found, the
@@ -5502,18 +5520,21 @@ to avoid infinite loops.
When a replacement is to be made, @var{replacement} is inserted into
the expansion, with @[EMAIL PROTECTED] substituted by the text matched by
-the @var{n}th parenthesized sub-expression of @var{regexp}, @samp{\&}
-being the text the entire regular expression matched.
+the @var{n}th parenthesized sub-expression of @var{patsubst}, for up to
+nine sub-expressions. The escape @samp{\&} is replaced by the text of
+the entire regular expression matched. For all other characters,
[EMAIL PROTECTED] treats the next character literally. A warning is issued if
+there were fewer sub-expressions than the @[EMAIL PROTECTED] requested, or
+if there is a trailing @samp{\}.
The @var{replacement} argument can be omitted, in which case the text
matched by @var{regexp} is deleted.
-The builtin macro @code{patsubst} is recognized only when given
-arguments.
+The macro @code{patsubst} is recognized only with parameters.
@end deffn
-When used with two arguments, while @code{regexp} returns the position
-of the match, @code{patsubst} deletes it:
+When used with two arguments, @code{regexp} returns the position of the
+match, but @code{patsubst} deletes the match:
@example
patsubst(`GNUs not Unix', `^', `OBS: ')
@@ -5526,14 +5547,26 @@ patsubst(`GNUs not Unix', `\w+', `(\&)')
@result{}(GNUs) (not) (Unix)
patsubst(`GNUs not Unix', `[A-Z][a-z]+')
@result{}GN [EMAIL PROTECTED] }
+patsubst(`GNUs not Unix', `not', `NOT\')
[EMAIL PROTECTED]:stdin:6: Warning: patsubst: trailing \ ignored in replacement
[EMAIL PROTECTED] NOT Unix
@end example
Here is a slightly more realistic example, which capitalizes individual
words or whole sentences, by substituting calls of the macros
@code{upcase} and @code{downcase} into the strings.
[EMAIL PROTECTED] Composite upcase (@var{text})
[EMAIL PROTECTED] Composite downcase (@var{text})
[EMAIL PROTECTED] Composite capitalize (@var{text})
+Expand to @var{text}, but with capitalization changed: @code{upcase}
+changes all letters to upper case, @code{downcase} changes all letters
+to lower case, and @code{capitalize} changes the first character of each
+word to upper case and the remaining characters to lower case.
[EMAIL PROTECTED] deffn
+
@example
-define(`upcase', `translit(`$*', `a-z', `A-Z')')dnl
+define(`upcase', `translit(`$*', `a-z', `A-Z')')dnl
define(`downcase', `translit(`$*', `A-Z', `a-z')')dnl
define(`capitalize1',
`regexp(`$1', `^\(\w\)\(\w*\)',
@@ -5559,7 +5592,7 @@ patsubst(`bar foo baz Foo', `\(\w*\) \(f
While @code{regexp} replaces the whole input with the replacement as
soon as there is a match, @code{patsubst} replaces each
[EMAIL PROTECTED] of a match and preserves non matching pieces:
[EMAIL PROTECTED] of a match and preserves non-matching pieces:
@example
define(`patreg',
@@ -5573,6 +5606,14 @@ patreg(`aba abb 121', `\(.\)\(.\)\1', `\
@result{}bab
@end example
+Omitting @var{regexp} evokes a warning, but still produces output.
+
[EMAIL PROTECTED]
+patsubst(`abc')
[EMAIL PROTECTED]:stdin:1: Warning: patsubst: too few arguments: 1 < 2
[EMAIL PROTECTED]
[EMAIL PROTECTED] example
+
@node Format
@section Formatting strings (printf-like)
Index: modules/m4.c
===================================================================
RCS file: /sources/m4/m4/modules/m4.c,v
retrieving revision 1.97
diff -u -p -r1.97 m4.c
--- modules/m4.c 23 Dec 2006 00:02:20 -0000 1.97
+++ modules/m4.c 27 Dec 2006 14:12:17 -0000
@@ -938,7 +938,15 @@ M4BUILTIN_HANDLER (index)
substring extends to the end of the first argument. */
M4BUILTIN_HANDLER (substr)
{
- int start, length, avail;
+ int start = 0;
+ int length;
+ int avail;
+
+ if (argc <= 2)
+ {
+ obstack_grow (obs, M4ARG (1), strlen (M4ARG (1)));
+ return;
+ }
length = avail = strlen (M4ARG (1));
if (!m4_numeric_arg (context, argc, argv, 2, &start))
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