Lines::Containing - look for lines containing a given needle

use Lines::Containing;

# lines with an "a"
.say for lines-containing("foo\nbar\nbaz", "a")  # bar␤baz␤

# lines ending on "r", with their line number
.say for lines-containing("foo\nbar\nbaz", / r $/, :kv);  # 1␤bar␤

# line numbers of lines starting with "f", starting at 1
.say for lines-containing("foo\nbar", *.starts-with("b"), :k, :offset(1));  # 2␤

# number of lines starting with "b", with their line number
.say for lines-containing("foo\nbar\nbaz", *.starts-with("b"), :count-only);  # 2␤

Lines::Containing provides a single subroutine lines-containing that allows searching for a string in an object that can produce something akin to lines of text.

The lines-containing subroutine can either take a Seq or Iterator producing lines, an array with lines, a Hash (or Map) with lines as values, or any other object that supports a lines method producing lines (such as Str, IO::Path, IO::Handle, Supply) as the source to check.

As the second parameter, it takes either a Cool object, a regular expression, or a Callable as the needle to search for.

It returns a (potentially lazy) Seq of the lines that contained the needle.

If a Callable was specified as the second parameter, then the following rules apply:

• if Bool was returned

Produce if True, or if :invert-match is specified, if False.

• if Empty was returned

Always produce the original line.

• anything else

Produce whatever was returned by the Callable otherwise.

Additionally, it supports the following named arguments:

• :count-only

Only produce a count of lines that have a match.

• :k

Produce line numbers only, or keys only in case of a Hash.

• :kv

Produce line number (or key in case of a Hash) and line alternately.

• :i or :ignorecase

Ignore case (only if the needle is a Str).

• :invert-match

Only produce lines that do NOT match.

• :m or :ignoremark

Ignore mark (only if the needle is a Str).

• :max-count=N

Maximum number of matches that will be produced. Defaults to Any, which indicates that all matches must be produced.

• :offset=N

The line number of the first line in the source (defaults to 0).

• :p

Produce Pairs with the line number (or the key in case of a Hash) as the key.

• :type=words|starts-with|ends-with|contains

Only makes sense if the needle is a Cool object. With words specified, will look for needle as a word in a line, with starts-with will look for the needle at the beginning of a line, with ends-with will look for the needle at the end of a line, with contains will look for the needle at any position in a line. Which is the default.

• :v (default)

Produce lines only.

The has-word subroutine, as provided by the version of has-word that is used.

Elizabeth Mattijsen liz@raku.rocks

Source can be located at: https://github.com/lizmat/Lines-Containing . Comments and Pull Requests are welcome.

If you like this module, or what I’m doing more generally, committing to a small sponsorship would mean a great deal to me!

Copyright 2022 Elizabeth Mattijsen

This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.