If in an XSLT 2 regular expression I want to match a literal curly brace,
what do I have to put in the regex?

For example, if my input string is " {some text}"

And I want to match any string that is enclosed in curly braces, with
optional whitespace before and after, I've tried:

matches(., '^\s*{.+}\s*$')
matches(., '^\s*{{.+}}\s*$')
matches(., '^\s*\{.+\}\s*$')
matches(., '^\s*\{{.+\}}\s*$')

There are inside a predicate inside a select attribute in my XSL file. All
are rejected as syntax errors.

What's the right way of doing this?

This
  matches(. , '^\s*\{[^\}]+\}\s*$')
works for me with Saxon and Altova.

	Martin Honnen
	http://msmvps.com/blogs/martin_honnen/