fn:matches function
The fn:matches function determines whether a string matches a given pattern.
Syntax
>>-fn:matches(source-string,pattern-+--------+-)--------------->< '-,flags-'
- source-string
- A string that is compared to a pattern.
source-string is a literal string, or an XQuery expression that resolves to an xs:string value or the empty sequence.
- pattern
- A regular expression that is compared to source-string.
A regular expression is a set of characters, pattern-matching characters,
and operators that define a string or group of strings in a search
pattern.
pattern is string literal.
- flags
- A string literal that can contain any of the following values
that control matching of pattern to source-string:
- s
- Indicates that the dot (.) matches any character.
If the s flag is not specified, the dot (.) matches any character except the new line character (#x0A).
- m
- Indicates that the caret (^) matches the start of any line (the
position after a new line character), and the dollar sign ($) matches
the end of any line (the position before a new line character).
If the m flag is not specified, the caret (^) matches the start of the entire string, and the dollar sign ($) matches the end of the entire string.
- i
- Indicates that matching is case-insensitive for the letters "a"
through "z" and "A" through "Z".
If the i flag is not specified, case-sensitive matching is done.
- x
- Indicates that whitespace characters (#x09, #x0A, #x0D, and #x20)
within pattern are ignored, unless they are within
a character class. Whitespace characters in a character class are
never ignored.
If the x flag is not specified, whitespace characters are used for matching.
Returned value
If source-string is not the empty sequence, the returned value is an xs:boolean value that is true if source-string matches pattern. The returned value is false if source-string does not match pattern.
The rules for matching are:
- If pattern does not contain the string-starting or line-starting character caret (^), or the string-ending or line-ending character dollar sign ($), source-string matches pattern if any substring of source-string matches pattern.
- If pattern contains the string-starting or line-starting character caret (^), source-string matches pattern only if source-string matches pattern from the beginning of source-string or the beginning of a line in source-string.
- If pattern contains the string-ending or line-ending character dollar sign ($), source-string matches pattern only if source-string matches pattern at the end of source-string or at the end of a line of source-string.
- The m flag determines:
- Whether a match occurs from the beginning of the string or the beginning of a line
- Whether a match occurs from the end of the string or the end of a line.
If source-string is the empty sequence, source-string is considered to be a string of length 0, and source-string matches pattern if pattern matches a string of length 0.
Examples
fn:matches("abbcacadbdcd","(ac)|(bd)")
The returned value is true.
fn:matches("bd","^(ac)|(bd)$")
The returned value is true.