package VCP::Filter::map;

=head1 NAME

VCP::Filter::map - rewrite name and branch number.

=head1 SYNOPSIS

  ## From the command line:
   vcp <source> map: p1 r1   p2 r2 -- <dest>

  ## In a .vcp file:

    Map:
            path_glob_1<branch_1> path_out_1<branch_result_1>
            path_glob_2<branch_2> path_out_2<branch_result_2>
            # ... etc ...

=head1 DESCRIPTION

Maps source files, revisions, and branches to destination files and
branches while copying a repository.  This is done by rewriting the name
and branch_id of revisions according to a list of rules.

=head2 Rules

A rule is a pair of expressions specifying a pattern to match against
the each incoming revision's name and branch_id and a result to use to
replace the revision's name and branch_id.

The list of rules is evaluated top down; the last rule in the list that
matches is used to generate the new name and branch_id.  There is a
default rule that applies to all files

Note that sorting is performed in the destination, so the map will
affect the sort order and the original file name and branch_id are lost.

=head2 Patterns and Rule Expressions

Patterns and rules are composed of two subexpressions, the
C<path_expr> and the C<branch_expr> like so:

    path_expr<branch_expr>

The C<< <branch_expr> >> (including angle brackets) is optional and may
be forbidden by some sources or destinations that embed the concept of a
branch in the path_part.  (See L<VCP::Dest::p4|VCP::Dest::p4> for an
example, though this may be changed in the future).

For now, the symbols C<#> and C<@> are reserved for future used in all
expressions and must be escaped using C<\>, and various shell-like
wildcards are implemented in pattern expressions.

=head2 Pattern Expressions

Both the C<path_expr> and C<branch_expr> specify patterns using shell
regular expression syntax with the extension that parenthesese are used
to extract portions of the match in to numbered variables which may be
used in the result construction, like Perl regular expressions:

   ?      Matches one character other than "/"
   *      Matches zero or more characters other than "/"
   ...    Matches zero or more characters, including "/"
   (foo)  Matches "foo" and stores it in the $1, $2, etc

Some example pattern C<path_expr>s are:

   Pattern
   path_expr  Matches
   =========  =======
   foo        the top level file "foo"
   foo/bar    the file "foo/bar"
   ...        all files (like a missing path_expr)
   foo/...    all files under "foo/"
   .../bar    all files named "bar" anywhere
   */bar      all files named "bar" one dir down
   ....pm     all files ending in ".pm"
   ?.pm       all top level 4 char files ending in ".pm"
   \?.pm      the top level file "?.pm"
   (*)/...    all files in subdirs, puts the top level dirname in $1

Unix-style slashes are used, even on operating systems where that may
not be the preferred local custom.  The characters C<#>, C<@>, C<[>,
C<]>, C<{>, C<}>, C<E<gt>>, C<E<lt>> and C<$> are not permitted in
pattern expressions and must be escaped using a C<\>, as must any
wildcard characters meant to be taken literally (this is true in result
expressions as well).

Relative paths are taken relative to the rev_root indicated in the
source specification for pattern C<path_expr>s (or in the destination
specification for result C<path_expr>s).  For now, a relative path is a
path that does not begin with the character C</>, so be aware that the
pattern C<(/)> is relative.  This is a limitation of the implementation
and may change, until it does, don't rely on a leading "(" making a path
relative and use multiple rules to match multiple absolute paths.

If no C<path_expr> is provided, C<...> is assumed and the pattern will
match on all filenames.

Some example pattern C<branch_expr>s are:

    Pattern
    branch_expr  Matches files on
    ===========  ================
    <>           no branch
    <...>        all branches (like a missing <branch_expr>
    <foo>        branch "foo"
    <R...>       branches beginning with "R"
    <R(...)>     branches beginning with "R", the other chars in $1

If no C<branch_expr> is provided, files on all branches are matched.
C<*> and C<...> still match differently in pattern C<branch_expr>s, as
in <path_expr> patterns, but this is likely to make no difference, as
I've not yet seen a branch label with a "/" in it.  Still, it is wise
to avoid "*" in C<branch_expr> patterns.

Some example composite patterns are (any $ variables set
are given in parenthesis):

    Pattern            Matches
    =======            =======
    foo<>              top level files named "foo" not on a branch
    (...)<>            all files not on a branch ($1)
    (...)/(...)<>      all files not on a branch ($1,$2)
    ...<R1>            all files on branch "R1"
    .../foo<R...>      all files "foo" on branches beginning with "R"
    (...)/foo<R(...)>  all files "foo" on branches beginning with "R" ($1, $2)

=head2 Result Expressions

Result expressions look a lot like patthern expressions except that
wildcards are not allowed and C<$1> and C<${1}> style variable
interpolation is.  The characters C<@>, C<#>, C<E<gt>>, C<E<lt>> must be
escaped, and C<$> must be escaped if meant to be taken literally.

=head2 Command Line Parsing

For large maps or repeated use, the map is best specified in a .vcp
file.  For quick one-offs or scripted situations, however, the map:
scheme may be used on the command line.  In this case, each parameter
is a "word" and every pair of words is a ( pattern, result ) pair.

Because L<vcp|vcp> command line parsing is performed incrementally and
the next filter or destination specifications can look exactly like
a pattern or result, the special token "--" is used to terminate the
list of patterns if map: is from on the command line.  This may also
be the last word in the C<Map:> section of a .vcp file, but that is
superfluous.  It is an error to use "--" before the last word in a .vcp
file.

=for test_script t/61map.t

=cut

$VERSION = 1 ;

use strict ;
use VCP::Filter;
use Getopt::Long;
use base qw( VCP::Filter );

use fields (
   'MAP_RULES',   ## The rules to apply
);

sub new {
   my $class = shift ;
   $class = ref $class || $class ;

   my $self = $class->SUPER::new( @_ ) ;

   ## Parse the options
   my ( $spec, $options ) = @_ ;

   {
      local *ARGV = $options ;
      GetOptions(
         "NoFreakinOptionsAllowed" => \undef,
      )
	 or $self->usage_and_exit ;
   }

   while ( @$options && $options->[0] ne "--" ) {
   }

   return $self ;
}


sub handle_rev {
   my VCP::Filter::map $self = shift;

   $self->dest->handle_rev( @_ );
}


=head1 AUTHOR

Barrie Slaymaker <barries@slaysys.com>

=head1 COPYRIGHT

Copyright (c) 2000, 2001, 2002 Perforce Software, Inc.
All rights reserved.

See L<VCP::License|VCP::License> (C<vcp help license>) for the terms of use.

=cut

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