[antlr-interest] Generating XML from a antlr grammer!

[Johannes Luber]

Oliver Zeigermann wrote:
> 2007/6/11, Johannes Luber <jaluber at gmx.de>:
> 
> He, Johannes!
> 
> Good observation.
> 
> Maybe we can have a version that checks the order using validating
> semantic predicates. That really would be a good example for their
> use.
> 
> What do you think?

I've created an implementation (see grammar below), but the error
reporting AND recovering is weak. For the XML file

<doc>
    <assembly>
        <name>Util</Name>
    </assembly>
</doc>

the following is being output:

"line 3:18 rule endTag failed predicate: {
$ElementScope::currentElementName == input.LA(2).text }?
line 4:4 rule endTag failed predicate: {
$ElementScope::currentElementName == input.LA(2).text }?"

The second message is a conundrum: If the value of currentElementName is
still "name", why does it accept the closing </doc>? Maybe you have
better idea regarding this problem.

Best regards,
Johannes Luber


parser  grammar XMLParser;

options {      tokenVocab=XMLLexer; }

scope ElementScope {
String currentElementName;
}

document  : element ;

element
    : startTag
        (element
        | PCDATA
        )*
        endTag
    | emptyElement
    ;

startTag
scope ElementScope;
	:	TAG_START_OPEN GENERIC_ID (attribute)* TAG_CLOSE {
$ElementScope::currentElementName = $GENERIC_ID.text; }
	;

attribute  : GENERIC_ID ATTR_EQ ATTR_VALUE ;

endTag
scope ElementScope;
	:	{ $ElementScope::currentElementName == input.LT(2).getText() }?
TAG_END_OPEN GENERIC_ID TAG_CLOSE ;

emptyElement : TAG_START_OPEN GENERIC_ID  (attribute)* TAG_EMPTY_CLOSE ;