match. Matching a pattern


The operator searches for a match of a
pattern in a string. Pattern could be a string with PCRE-Perl-compatible regular expression-or regex-object [3.4.0].
Some examples of PCRE are given in "Attachment 4: Perl Compatible Regular Expressions".

The following search
options may be used:

x-ignore "white space" characters and allow #comments till the end of the line;
s-regard $ as the end of the whole text (default);
m-regard $ as the end of the line, but not the whole text;
U-inverts the "greediness" of the quantifiers so that they are not greedy by default, but become greedy if followed by ?; [3.3.0]
-find not only the first, but all occurrences of the pattern;
n-return number of matches instead of table with search results; [3.2.2]
'-evaluate values for prematch, match, postmatch columns.

^ and $ are used in Parser's syntax, that is why if you want to include them in your pattern, they must be given as ^^ and ^$ respectively (see also Literals).

If option
g is specified, a table with the results of the match will be created with one row per each occurrence. If option g is not specified, a table with the results will contain only one record with first occurrence. If substring is not found, the result of operation will be empty table. If option n is specified, a number of matches will be returned instead of table.

A matches' table (object of class table) contain the next columns
1, 2, , n, prematch, match, postmatch, where
prematch is the column with substring coming from the beginning of the string to the place where the pattern-matching substring was found
match is the column with the pattern-matching substring
postmatch is the column with the substring that comes after pattern-matching substring and up to the end of the entire string
1, 2, , n are the columns with pattern-matching substrings enclosed in round brackets, where n is number of the left bracket

Note 1: values for
prematch, match, postmatch columns are evaluated only if option ' is specified.
Note 2: values for
1, 2, , n are evaluated only if round brackets used in pattern.
Note 3: you can use (?:...) instead of (...) in pattern if you don't need some parts of matches in table with results


match found}{match not found}

The code will output:
match found


The example will create a file
match.txt, with the following table:



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