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Paul Evans


Tickit::Utils - utility functions for Tickit


This module provides a number of utility functions used across Tickit.


$bytes = string_count( $str, $pos, $limit )

Given a string in $str and a Tickit::StringPos instance in $pos, updates the counters in $pos by counting the string, and returns the number of bytes consumed. If $limit is given, then it will count no further than any of the limits given.

$bytes = string_countmore( $str, $pos, $limit, $start )

Similar to string_count but will not zero the counters before it begins. Counters in $pos will still be incremented. If $start is provided it gives the byte offset within $str to begin counting from. This is more efficient than applying substr on the input string to create the starting point.

$cols = textwidth( $str )

Returns the number of screen columns consumed by the given (Unicode) string.

@cols = chars2cols( $text, @chars )

Given a list of increasing character positions, returns a list of column widths of those characters. In scalar context returns the first columns width.

@chars = cols2chars( $text, @cols )

Given a list of increasing column widths, returns a list of character positions at those widths. In scalar context returns the first character position.

$substr = substrwidth $text, $startcol

$substr = substrwidth $text, $startcol, $widthcols

$substr = substrwidth $text, $startcol, $widthcols, $replacement

Similar to substr, but counts start offset and length in screen columns instead of characters

( $before, $alloc, $after ) = align( $value, $total, $alignment )

Returns a list of three integers created by aligning the $value to a position within the $total according to $alignment. The sum of the three returned values will always add to total.

If the value is not larger than the total then the returned allocation will be the entire value, and the remaining space will be divided between before and after according to the given fractional alignment, with more of the remainder being allocated to the $after position in proportion to the alignment.

If the value is larger than the total, then the total is returned as the allocation and the before and after positions will both be given zero.

$val = bound( $min, $val, $max )

Returns the value of $val bounded by the given minimum and maximum. Either limit may be left undefined, causing no limit of that kind to be applied.

distribute( $total, @buckets )

Given a total amount of quota, and a list of buckets, distributes the quota among the buckets according to the values given in them.

Each value in the @buckets list is a HASH reference which will be modified by the function. On entry, the following keys are inspected.

base => INT

If present, this bucket shall be a flexible bucket containing initially this quantity of quota, but may be allocated more, or less, depending on the value of the expand key, and how much spare is remaining.

expand => INT

For a base flexible bucket, the relative distribution of expand value among the flexible buckets determines how the spare quota is distributed among them. If absent, defaults to 0.

fixed => INT

If present, this bucket shall be of the exact fixed size given.

On return, the bucket hashes will be modified to contain two more keys:

value => INT

The amount of quota allocated to this bucket. For fixed buckets, this will be the fixed value. For base buckets, this may include extra spare quota distributed in proportion to the expand value, or may be reduced in order to fit the total.

start => INT

Gives the cumulative amount of quota allocated to each previous bucket. The first bucket's start value will be 0, the second will be the value allocated to the first, and so on.

The bucket hashes will not otherwise be modified; the caller may place any extra keys in the hashes as required.


Paul Evans <leonerd@leonerd.org.uk>