Editing Wikiq (section)

=== Pattern matching arguments ===

Users can now search for patterns in edit revision text, with a list of matches for each edit being output in columns (a column for each pattern indicated by the pattern arguments below). Users may provide multiple revision patterns and accompanying labels. The patterns and the labels must be provided in the same order for wikiq to be able to correctly label the output columns.

<code>-RP</code> <code>--revision-pattern</code>: a regular expression

<code>-RPl</code> <code>--revision-pattern-label</code>: a label for the columns output based on matching revisions against the pattern.

In addition to revisions, we also wish to support pattern matching against revision ''summaries'' (comments). Therefore we also have corresponding command line arguments.

<code>-CP</code> <code>--comment-pattern</code>: a regular expression 

<code>-CPl</code> <code>--comment-pattern-label</code>: a label for the columns output based on matching revisions against the pattern.

==== A note on named capture groups in pattern matching ====

The regular expressions in <code>-RP</code> and <code>-CP</code> may include one or more [https://docs.python.org/3.7/howto/regex.html#non-capturing-and-named-groups named capture groups]. If the `pattern` matches, it will then also capture values for each named capture group. If a <code>pattern</code> has one or more ''named capture groups'' wikiq will output a new column for each named capture group to store these values, with the column getting named: <code>&lt;pattern-label&gt;_&lt;capture-group-name&gt;</code>. Since a `pattern` can match a revision more than once it is possible that more than one value should go in this column (regardless of named capture group or not).

For cases in which the <code>-RP</code> or <code>-CP</code> have more than one named capture group and part of the searched string being searched matches for more than one capture group, only the first capture group will indicate a match because matching consumes characters in Python. For example, if a regular expression is <code>r"(?P<3_letters>\b\w{3}\b)|(?P<number>\b\d+\b)"</code> and the test string being searched is <code>dog and 500 bits of kibble</code>, we note that <code>500</code> works for both the <code>3_letters</code> and <code>number</code>. However, the capture group listed first (<code>3_letters</code>) consumes '500' when it matches, so the <code>3_letters</code> column will contain the list <code>[dog, and, 500]</code> while the <code>number</code> column will simple have <code>None</code>. As a result, one should consider the order of capture groups or create separate regular expression and label pairs.