[svn:perl6-synopsis] r7860 - doc/trunk/design/syn
Author: larry
Date: Fri Feb 24 16:04:13 2006
New Revision: 7860
Modified:
doc/trunk/design/syn/S05.pod
Log:
* Added $() access to result object.
* Added ( pat ) matcher to capture simple result object.
* Changed old (...) assertion to ?{...} and !{...},
which is more consistent with other callouts to code.
Modified: doc/trunk/design/syn/S05.pod
==
--- doc/trunk/design/syn/S05.pod(original)
+++ doc/trunk/design/syn/S05.podFri Feb 24 16:04:13 2006
@@ -13,9 +13,9 @@
Maintainer: Patrick Michaud [EMAIL PROTECTED]
Date: 24 Jun 2002
- Last Modified: 24 Feb 2006
+ Last Modified: 25 Feb 2006
Number: 5
- Version: 10
+ Version: 11
This document summarizes Apocalypse 5, which is about the new regex
syntax. We now try to call them rules because they haven't been
@@ -613,24 +613,40 @@
=item *
-A leading C( indicates a code assertion:
+A leading C?{ or C!{indicates a code assertion:
- / (\d**{1..3}) ( $0 256 ) /
+ / (\d**{1..3}) ?{ $0 256 } /
+ / (\d**{1..3}) !{ $0 256 } /
Similar to:
/ (\d**{1..3}) { $0 256 or fail } /
+ / (\d**{1..3}) { $0 256 and fail } /
Unlike closures, code assertions are not guaranteed to be run at the
canonical time if the optimizer can prove something later can't match.
So you can sneak in a call to a non-canonical closure that way:
- /^foo .* ( do { say Got here! } or 1 ) .* bar$/
+ /^foo .* ?{ do { say Got here! } or 1 } .* bar$/
The Cdo block is unlikely to run unless the string ends with Cbar.
=item *
+A leading C( indicates the start of a result capture:
+
+/ foo ( \d+ ) bar /
+
+is equivalent to:
+
+/ before foo \d+ after bar /
+
+except that the scan for foo can be done in the forward direction,
+when a lookbehind assertion would scan for \d+ and then match foo
+backwards.
+
+=item *
+
A leading C[ or C+ indicates an enumerated character class. Ranges
in enumerated character classes are indicated with C...
@@ -1041,14 +1057,19 @@
=item *
-A match always returns a match object, which is also available as
-(lexical) C$/ (except within a closure lexically embedded in a rule,
-where C$/ always refers to the current match, not any submatch done
-within the closure).
+A match always returns a match object, which is also available
+as C$/, which is an environmental lexical declared in the outer
+subroutine that is calling the rule. (A closure lexically embedded
+in a rule does not redeclare C$/, so C$/ always refers to the
+current match, not any prior submatch done within the closure).
=item *
-The match object evaluates differently in different contexts:
+Notionally, a match object contains (among other things) a boolean
+success value, a scalar result object, an array of ordered submatch
+objects, and a hash of named submatch objects. To provide convenient
+access to these various values, the match object evaluates differently
+in different contexts:
=over
@@ -1083,7 +1104,7 @@
=item *
-When used as a closure, a Match object evaluates to its underlying
+When called as a closure, a Match object evaluates to its underlying
result object. Usually this is just the entire match string, but
you can override that by calling Creturn inside a rule:
@@ -1093,6 +1114,18 @@
# match succeeds -- ignore the rest of the rule
}.();
+C$() is a shorthand for C$/.() or C$/(). The result object
+may contain any object, not just a string.
+
+You may also capture a subset of the match as the result object using
+the C (...) construct:
+
+foo123bar ~~ / foo ( \d+ \ bar /
+say $();# says 123
+
+In this case the result object is always a string when doing string
+matching, and a list of one or more elements when doing array matching.
+
=item *
When used as an array, a Match object pretends to be an array of all
@@ -1175,9 +1208,19 @@
incomplete CMatch object (which can be modified via the internal C$/.
For example:
- $str ~~ / foo# Match 'foo'
+$str ~~ / foo# Match 'foo'
{ $/ = 'bar' } # But pretend we matched 'bar'
/;
+say $/; # says 'bar'
+
+This is slightly dangerous, insofar as you might return something that
+does not behave like a CMatch object to some context that requires
+one. Fortunately, you normally just want to return a result object instead:
+
+$str ~~ / foo # Match 'foo'
+ { return 'bar' } # But pretend we matched 'bar'
+ /;
+say $(); # says 'bar'
=back
[svn:perl6-synopsis] r7863 - doc/trunk/design/syn
Author: larry
Date: Sat Feb 25 00:29:54 2006
New Revision: 7863
Modified:
doc/trunk/design/syn/S02.pod
doc/trunk/design/syn/S03.pod
doc/trunk/design/syn/S04.pod
doc/trunk/design/syn/S05.pod
Log:
Various tweaks and comments from TheDamian.
Modified: doc/trunk/design/syn/S02.pod
==
--- doc/trunk/design/syn/S02.pod(original)
+++ doc/trunk/design/syn/S02.podSat Feb 25 00:29:54 2006
@@ -12,9 +12,9 @@
Maintainer: Larry Wall [EMAIL PROTECTED]
Date: 10 Aug 2004
- Last Modified: 16 Feb 2006
+ Last Modified: 25 Feb 2006
Number: 2
- Version: 16
+ Version: 17
This document summarizes Apocalypse 2, which covers small-scale
lexical items and typological issues. (These Synopses also contain
@@ -111,7 +111,7 @@
=item *
In support of OO encapsulation, there is a new fundamental datatype:
-Bopaque. External access to opaque objects is always through method
+BP6opaque. External access to opaque objects is always through method
calls, even for attributes.
=item *
@@ -211,9 +211,11 @@
=item *
-Perl 6 intrinsically supports big integers and rationals through
-its system of type declarations. CInt automatically supports
-promotion to arbitrary precision. CRat supports arbitrary precision
+Perl 6 intrinsically supports big integers and rationals through its
+system of type declarations. CInt automatically supports promotion
+to arbitrary precision. (CNum may support arbitrary-precision
+floating-point arithmatic, but is not required to unless we can do
+so portably and efficiently.) CRat supports arbitrary precision
rational arithmetic. Value types like Cint and Cnum imply
the natural machine representation for integers and floating-point
numbers, respectively, and do not promote to arbitrary precision.
Modified: doc/trunk/design/syn/S03.pod
==
--- doc/trunk/design/syn/S03.pod(original)
+++ doc/trunk/design/syn/S03.podSat Feb 25 00:29:54 2006
@@ -12,9 +12,9 @@
Maintainer: Larry Wall [EMAIL PROTECTED]
Date: 8 Mar 2004
- Last Modified: 1 Feb 2006
+ Last Modified: 25 Feb 2006
Number: 3
- Version: 12
+ Version: 13
=head1 Operator renaming
@@ -107,10 +107,10 @@
of semantics. Anywhere you used C=~ before you now use C~~, but C~~ is
much more general now. See LSynopsis 4 for details. (To catch brainos,
the Perl 6 parser defines an C infix:=~ macro which always fails at
-compile time with a message directing the user either to use C~~ instead,
+compile time with a message directing the user either to use C~~ or C~=
instead,
or to put a space between if they really wanted to assign a stringified value.)
-=item * Unary C. calls its single argument (which must be a method, or an
+=item * Unary C. calls its single argument (which must be a method, or a
dereferencer for a hash or array) on C$_.
=item * The C.. range operator has variants with C^ on either
@@ -118,10 +118,18 @@
produces a Range object. Range objects are lazy iterators, and can
be interrogated for their current C.min and C.max values (which
change as they are iterated). Ranges are not autoreversing: C2..1
-is always a null range, as is C1^..^2. However, smart matching
-against a Range object smartmatches the endpoints in the domain of
-the object being matched, so C 1.5 ~~ 1^..^2 is true.
-(But C 2.1 ~~ 1..2 is false.)
+is always a null range, as is C1^..^2. To reverse a range use:
+
+2..1:by(-1)
+reverse 1..2
+
+(The Creverse is preferred because it works for alphabetic ranges
+as well.)
+
+Because CRange objects are lazy, they do not automatically generate
+a list. So smart matching against a Range object smartmatches the
+endpoints in the domain of the object being matched, so C 1.5 ~~
+1^..^2 is true. (But C 2.1 ~~ 1..2 is false.)
=item * The unary C^ operator generates a range from C0 up to
one less than its argument. so C^4 is short for C0..^4 or C0..3.
@@ -133,7 +141,7 @@
=item * However, C... as a term is the yada, yada, yada operator,
which is used as the body in function prototypes. It complains
-bitterly if it is ever executed. Actually, it calls Cfail. Variant
+bitterly (by calling Cfail) if it is ever executed. Variant
C??? calls Cwarn, and C!!! calls Cdie.
=item * In addition, to the ordinary C. method invocation, there are
@@ -432,7 +440,7 @@
=head1 Precedence
-Perl 6 has 22 precedence levels (fewer than Perl 5):
+Perl 6 has 22 precedence levels (which is fewer than Perl 5):
terms 42 eek $x /abc/ (1+2) a(1) :by(2) .meth listop
method postfix . .+ .? .* .() .[] .{} .«» .=
Modified: doc/trunk/design/syn/S04.pod
==
--- doc/trunk/design/syn/S04.pod(original)
+++ doc/trunk/design/syn/S04.podSat Feb 25 00:29:54 2006
@@ -12,9 +12,9
[svn:perl6-synopsis] r7867 - doc/trunk/design/syn
Author: autrijus
Date: Sat Feb 25 01:59:19 2006
New Revision: 7867
Modified:
doc/trunk/design/syn/S05.pod
Log:
* S05: Fix the (...) typo (was spelled (...\) and
make the moose example slightly more idiomatic.
Modified: doc/trunk/design/syn/S05.pod
==
--- doc/trunk/design/syn/S05.pod(original)
+++ doc/trunk/design/syn/S05.podSat Feb 25 01:59:19 2006
@@ -1115,17 +1115,17 @@
my $moose = m:{
antler body
-{ return Moose.new( body = $body.attach(:$antler) ) }
+{ return Moose.new( body = $body().attach($antler()) ) }
# match succeeds -- ignore the rest of the rule
}.();
C$() is a shorthand for C$/.() or C$/(). The result object
-may contain any object, not just a string.
+may be of any type, not just a string.
You may also capture a subset of the match as the result object using
the C (...) construct:
-foo123bar ~~ / foo ( \d+ \ bar /
+foo123bar ~~ / foo ( \d+ ) bar /
say $();# says 123
In this case the result object is always a string when doing string
[svn:perl6-synopsis] r7866 - doc/trunk/design/syn
Author: larry Date: Sat Feb 25 01:58:24 2006 New Revision: 7866 Modified: doc/trunk/design/syn/S05.pod Log: Fixed and clarified (...) definition. Modified: doc/trunk/design/syn/S05.pod == --- doc/trunk/design/syn/S05.pod(original) +++ doc/trunk/design/syn/S05.podSat Feb 25 01:58:24 2006 @@ -639,11 +639,16 @@ is equivalent to: -/ before foo \d+ after bar / +/ after foo \d+ before bar / except that the scan for foo can be done in the forward direction, -when a lookbehind assertion would scan for \d+ and then match foo -backwards. +while a lookbehind assertion would presumably scan for \d+ and then +match foo backwards. The use of C (...) affects only the +meaning of the result object and the positions of the beginning and +ending of the match. That is, after the match above, C$() contains +only the digits matched, and C.pos is pointing to after the digits. +Other captures (named or numbered) are unaffected and may be accessed +through C$/. =item *
[svn:perl6-synopsis] r7869 - doc/trunk/design/syn
Author: larry
Date: Sat Feb 25 02:30:24 2006
New Revision: 7869
Modified:
doc/trunk/design/syn/S04.pod
Log:
Example was still in superpositional Perl[5|6]. dconway++ lwall--
Modified: doc/trunk/design/syn/S04.pod
==
--- doc/trunk/design/syn/S04.pod(original)
+++ doc/trunk/design/syn/S04.podSat Feb 25 02:30:24 2006
@@ -210,9 +210,10 @@
The list is evaluated lazily by default, so instead of using a Cwhile
to read a file a line at a time as you would in Perl 5:
-while my $line = $*IN {...}
+while (my $line = STDIN) {...}
-in Perl 6 you should use a Cfor instead:
+in Perl 6 you should use a Cfor (plus a unary C= iterate the
+iterator operator) instead:
for =$*IN - $line {...}
