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NAME
====

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

SYNOPSIS
========

```raku
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␤
```

DESCRIPTION
===========

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.

EXPORTED SUBROUTINES
====================

lines-containing
----------------

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 `Pair`s 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.

has-word
--------

The `has-word` subroutine, as provided by the version of [has-word](https://raku.land/zef:lizmat/has-word) that is used.

AUTHOR
======

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](https://github.com/sponsors/lizmat/) would mean a great deal to me!

COPYRIGHT AND LICENSE
=====================

Copyright 2022 Elizabeth Mattijsen

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