[TxMt] Search and replace matching brackets?

[Robin Houston]

Excellent, glad it was helpful.

It really ought to be possible to combine subexpression calls and back
references to do things like matching well-formed XML elements.
Unfortunately this doesn't work with the Onigurama engine, because
subexpression calls mess up back referencing. That's a real shame: it
does work in PCRE.

If you change \k<name> to \g<name> in the code below, then it will
work (but then of course it doesn't check that the closing tag has the
same name as the opening one).

Robin


(?x) # Enable layout and comments

(?<element>
	(?<stag>
		<
		(?<name>
			# An XML name begins with a letter, underscore or colon:
			[[:alpha:]_:]
			# followed by a sequence of NameChars (see the XML definition):
			[[:alnum:].\-_:]*
		)
		(?<attr>
			# In XML, the whitespace chars are space, tab, CR and LF.
			(?<space>[\ \t\r\n]+)
			\g<name>\g<space>?=\g<space>?
			(?<attrval>
				'[^']*' | "[^"]*"
			)
		)*
		\g<space>?
		>
	)
	(?<content>
		[^<]  # This is not quite technically correct, but is probably good enough
		|
		\g<element>
	)*
	(?<etag>
		</ \k<name> \g<space>? >
	)
	|
	(?<emptyelemtag>
		< \g<name> \g<attr>* \g<space>? />
	)
)