NAME

String::Compile::Tr - compile tr/// expressions

VERSION

Version 0.06

SYNOPSIS

use String::Compile::Tr;

my $search = '/+=';
my $replace = '-_';
my $s = 'De/0xv5y3w8BpLF8ubOo+w==';
trgen($search, $replace, 'd')->($s);
# $s = 'De-0xv5y3w8BpLF8ubOo_w'

DESCRIPTION

The usual approach when operands of a tr/// operator shall be variables is to apply eval on a string to interpolate the operands. The drawback of this approach are possible unwanted side effects induced by the variables' content, e.g.

$search = '//,warn-trapped,$@=~tr/';
eval "tr/$search//d";

String::Compile::Tr offers an alternative where the content of a variable can be used as operand without eval'ing it. Instead the operands of a tr/// operator are overloaded at runtime inside a constant eval '...'.

trgen(*SEARCH*, *REPLACE*, *OPT*) compiles an anonymous sub that performs almost the same operation as tr/*SEARCH*/*REPLACE*/*OPT*, but allows variable operands.

trgen is imported by default by use String::Compile::Tr.

FUNCTIONS

trgen

trgen(search, replace, [options])

trgen returns an anonymous subroutine that performs an almost identical operation as tr/search/replace/options. The tr target may be given as an argument to the generated sub or is the default input $_ otherwise.

ERRORS

trgen will throw an exception if an invalid option is specified or the tr operation cannot be compiled.

EXAMPLES

Proposed usages of this module are:

use String::Compile::Tr;

my $search = 'abc';
my $replace = '123';
my $tr = trgen($search, $replace);
my $s = 'fedcba';
$tr->($s);
# $s is 'fed321' now

my @list = qw(axy bxy cxy);
$tr->() for @list;
# @list is now ('1xy', '2xy', '3xy');

print trgen($search, $replace, 'r')->('fedcba'); # 'fed321'

RESTRICTIONS

Character ranges are not supported in the search and replace lists. All characters are interpreted literally. This is caused by the fact that tr does not support these neither. It's the compiler that expands character ranges in tr's operands before handing them over.

Overloading constants in eval '...' requires perl v5.10.

AUTHOR

Jörg Sommrey, <git at sommrey.de>

LICENSE AND COPYRIGHT

This software is copyright (c) 2025 by Jörg Sommrey.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

SEE ALSO

"tr/*SEARCHLIST*/*REPLACEMENTLIST*/cdsr" in perlop

"eval" in perlfunc

Exporter::Tiny::Manual::Importing

Regexp::Tr provides a similar functionality, though this eval's its oprands.