protected void MemorizeReference(ReferenceExp exp)
{
RefParseInfo pi = (RefParseInfo)refParseInfos[exp];
if (pi == null)
{
refParseInfos[exp] = pi = new RefParseInfo();
}
pi.MemorizeReference(reader);
}
protected virtual ReferenceExp Define()
{
string combine = GetAttribute("combine");
string name = GetAttribute("name");
if (name == null)
{
// error: missing attribute
ReportError(ERR_MISSING_ATTRIBUTE, reader.Name, "name");
reader.Skip();
return(null);
}
Expression body = Group(); // parse the body.
ReferenceExp exp = grammar.GetOrCreate(name);
CombineReferenceExp(exp, body, combine);
return(exp);
}
protected virtual Expression ParentRef()
{
string name = GetRequiredAttribute("name");
EmptyContent();
if (name == null)
{
// error: missing attribute
return(Expression.NotAllowed);
}
if (grammar == null || grammar.Parent == null)
{
// error: no-enclosing grammar
ReportError(ERR_NO_GRAMMAR);
return(Expression.NotAllowed);
}
ReferenceExp exp = grammar.Parent.GetOrCreate(name);
MemorizeReference(exp);
return(exp);
}
protected virtual void CombineReferenceExp(
ReferenceExp r, Expression body, string combine)
{
if (redefiningRefExps.ContainsKey(r))
{
// this pattern is currently being redefined.
redefiningRefExps[r] = true;
return; // ignore the value
}
RefParseInfo pi = (RefParseInfo)refParseInfos[r];
if (pi == null)
{
refParseInfos[r] = pi = new RefParseInfo();
}
if (pi.Combine != null && combine != null && pi.Combine != combine)
{
// error: inconsistent combine method
ReportError(ERR_INCONSISTENT_COMBINE, r.name);
pi.Combine = null;
return;
}
if (combine == null)
{
if (pi.HeadDefined)
{
// error: multiple heads
ReportError(ERR_MULTIPLE_HEADS, r.name);
}
pi.HeadDefined = true;
combine = pi.Combine;
}
else
{
pi.Combine = combine;
}
if (r.exp == null)
{
r.exp = body;
}
else
{
if (combine == "interleave")
{
r.exp = Builder.CreateInterleave(r.exp, body);
}
else
if (combine == "choice")
{
r.exp = Builder.CreateChoice(r.exp, body);
}
else
{
// error: invalid combine value
ReportError(ERR_INVALID_COMBINE, combine);
}
}
}
public virtual Expression OnRef(ReferenceExp exp)
{
return(exp.exp.Visit(this));
}
public void OnRef(ReferenceExp exp)
{
exp.exp.Visit(this);
}
