Ingy döt Net > String-Slice-0.01 > String::Slice



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String::Slice - Shared Memory Slices of Bigger Strings


    use String::Slice;

    my $buffer = fetch_enormous_string;
    my $slice;

    # Make $slice reference chars 101-125 of $buffer
    slice($slice, $buffer, 101, 25);

    # Make $slice reference chars 126-175 of $buffer
    slice($slice, $buffer, 25, 50);

    # Make $slice reference chars 120 to end of $buffer
    slice($slice, $buffer, -6);

    # Look for $pattern in $buffer,
    # at each 100 byte starting point
    $slice = '';    # Reset $slice
    for (my $i = 0; slice($slice, $buffer, $i); $i += 100) {
        if ($slice =~ /^$pattern/) { ... do it ... }


Processing large strings in Perl is inefficient because to access any smaller portion of a buffer you need to make a copy of that portion.

This module lets you make a string scalar point to a portion of the content of another string scalar.

The primary goal of this module is to make the parsing large data much faster in Perl.


String::Slice exports one function: slice. It can be called in a few different ways:

    slice($slice_variable, $big_buffer_variable, $char_offset, $char_length)

This effectively makes $slice_variable a substr of the buffer. The offset defaults to 0, and if no length is given, the slice goes to the end of the buffer. One side effect of this function is that both strings will become readonly, and the memory will not be freed until they both go out of scope.

If $slice is already a slice of $buffer then this call:

    slice($slice, $buffer, $offset, $length)

will move the offset forward by the specified number (or backwards if the offset is negative).

If length is too long, the slice will go to the end of the buffer.

The slice function returns 1 on success and 0 on failure. Failure occurs if the requested offset is invalid (less than the start or greater than or equal to the end of the buffer).


Thanks go out to Jan Dubois and Florian Ragwitz for help on how to do this right.


Ingy döt Net (ingy) <>


Copyright (c) 2012 Ingy döt Net


This library is free software and may be distributed under the same terms as perl itself.

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