Text::Template::Inline - Easy formatting of hierarchical data


Text-Template-Inline documentation Contained in the Text-Template-Inline distribution.

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NAME

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Text::Template::Inline - Easy formatting of hierarchical data

SYNOPSIS

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 # you can import any name you want instead of "render"
 use Text::Template::Inline 'render';

 # yields "Replace things and stuff."
 render {
    foo => 'things',
    bar => 'stuff',
 }, q<Replace {foo} and {bar}.>;

 # yields "Three Two One Zero"
 render [qw/ Zero One Two Three /], '{3} {2} {1} {0}';

 # for a blessed $obj that has id and name accessors:
 render $obj, '{id} {name}';

 # a "fat comma" can be used as syntactic sugar:
 render $obj => '{id} {name}';

 # it's also possible to traverse heirarchies of data,
 # even of different types.
 # the following yields "one two three"
 render {
    a => { d => 'one' },
    b => { e => 'two' },
    c => { f => [qw/ zero one two three /], },
 } => '{a.d} {b.e} {c.f.3}';

 # there's also an automatic unindent feature that
 # lines up to the least-indented line in the template:
 render {
    a => { d => 'one' },
    b => { e => 'two' },
    c => { f => [qw/ zero one two three /], },
 } => q{
    {a.d}
      {b.e}
        {c.f.3}
 };
 # the above results in this:
 'one
   two
     three
 '

DESCRIPTION

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This module exports a fuction render that substitutes identifiers of the form {key} with corresponding values from a hashref, listref or blessed object. It has features that work well with inline documents like heredocs, such as automatic unindent.

The implementation is very small and simple. The small amount of code is easy to review, and the resource cost of using this module is minimal.

EXPORTED FUNCTION

There is only one function defined by this module. It is exported automatically.

render ( $data, $template )

Each occurrence in $template of the form {key} will be substituted with the corresponding value from $data. If there is no such value, no substitution will be performed.

First $template is intelligently unindented and leading or trailing newlines are trimmed.

If $data is a blessed object, the keys in $template correspond to accessor methods. These methods should return a scalar when called without any arguments (other than the reciever).

if $data is a hash reference, the keys in $template correspond to the keys of that hash. Keys that contain non-word characters are not replaced.

if $data is a list reference, the keys in $template correspond to the indices of that list. Keys that contain non-digit characters are not replaced.

The modified $template string is then returned.

REQUIRES

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Scalar::Util

Test::More and Test::Exception (for installation)

BUGS

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If you find a bug in Text::Template::Inline please report it to the author.

AUTHOR

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 Zack Hobson <zgh@cpan.org>

COPYRIGHT

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Text-Template-Inline documentation Contained in the Text-Template-Inline distribution.

package Text::Template::Inline;
use strict;
use warnings;
use base 'Exporter';
our @EXPORT = qw/ render /;

use Carp qw/ croak /;
use Scalar::Util qw/ blessed reftype /;

our $VERSION = '0.13';

#
# The import function accepts an alternate name for the "render" function,
# then aliases and exports that name instead of the original.
#
sub import {
    my ($package, $func_name) = @_;
    local @EXPORT = @EXPORT;
    if ($func_name) {
        # export the provided name instead of "render"
        @EXPORT = ($func_name);
        no strict 'refs';
        *{$func_name} = *render;
    }
    $package->export_to_level(1,@_);
}

#
# This function is the only external module interface.
# If you don't like the name, just import a better one!
#
sub render ($$) {
    my ($data, $template) = @_;
    return $template unless $template;

    # Trim leading whitespace, preserving relative indent.
    # There's no way to know what your tabstops are, so we have to
    # assume that you indent consistently w/ regards to tabs/spaces.
    my $indent;
    while ($template =~ m/^([\t ]+)/mg) {
        my $lead = length $1;
        $indent = (defined $indent && $lead > $indent) ? $indent : $lead;
    }
    $template =~ s/^[\t ]{$indent}//mg if defined $indent;
    $template =~ s/^\n//; # remove leading newline

    # perform the data substitutions
    $template =~ s/(\{(\w[.\w]*)\})/_traverse_ref_with_path($data,$2,$1)/ge;

    return $template;
}

#
# This function dissects a period-delimited path of keys and follows them,
# traversing $theref. If the appropriate field exists at each level the final
# value is returned. If any field is not found, $default is returned.
#
sub _traverse_ref_with_path {
    my ($theref, $path, $default) = @_;
    my @keys = split /\./, $path;
    my $ref = $theref;
    for my $key (@keys) {
        no warnings 'uninitialized'; # for comparisons involving a non-ref $ref
        if (blessed $ref) {
            return $default unless $ref->can($key);
            $ref = $ref->$key();
        }
        elsif (reftype $ref eq 'HASH') {
            return $default unless exists $ref->{$key};
            $ref = $ref->{$key};
        }
        elsif (reftype $ref eq 'ARRAY') {
            return $default unless $key =~ /^\d+$/ and exists $ref->[$key];
            $ref = $ref->[$key];
        }
        else {
            local $Carp::CarpLevel = 2;
            croak "unable to use scalar '$theref' as template data";
        }
    }
    return $ref;
}

1;
__END__

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