public Assigned assigned_transitive(Object variable)
{
Assigned a = assigned(variable);
if (a != null)
{
return(a);
}
if (zuper != null)
{
return(zuper.assigned_transitive(variable));
}
return(null);
}
public Object assign(Object variable, Value value, bool is_final)
{
Assigned t = assigned(variable);
Value a = t != null ? t.value : null; // Existing value
if (a != null && a != value && variable != this)
{
throw new System.ArgumentException(pathname() + zuper_name() + " cannot have two assignments to " + variable.pathname());
}
if (variable.is_syntax)
{
syntax = value as RegexValue;
return(variable); // Not used, but flags that we succeeded
}
else
{
return(new Assignment(this, variable, value, is_final));
}
}
private Object assignment(Object variable)
{
string op;
if ((op = expect("equals")) != null || (op = expect("approx")) != null)
{
bool is_final = op == "=";
opt_white();
Object parent = context.stacktop;
Assigned existing = parent.assigned(variable);
if (existing != null)
{
error("Cannot reassign " + parent.name + "." + variable.name + " from " + existing.ToString());
}
Object controlling_syntax = variable;
Object refine_from = null;
Value val;
if (variable.is_syntax)
{ // Parse a Regular Expression
string regexp_string = expect("regexp");
List <string> path_with_syntax;
Object existing_object;
Assigned assigned_syntax;
if (regexp_string != null)
{
val = new RegexValue(regexp_string);
}
else if ((path_with_syntax = path_name()) != null &&
(existing_object = @context.resolve_name(path_with_syntax)) != null &&
(assigned_syntax = existing_object.assigned(@context.syntax)) != null
)
{
val = assigned_syntax.value as RegexValue;
}
else
{
error("Assignment to Syntax variable requires a regular expression");
val = null; // Will not be reached, but prevents compile error
}
}
else
{
if (variable.is_reference)
{
Assigned overriding = parent.assigned_transitive(variable);
if (overriding == null)
{
overriding = variable.assigned(variable);
}
if (overriding != null && overriding.final) // Final
{
if (overriding.value is ArrayValue) // the Value is an array
{
refine_from = ((overriding.value as ArrayValue).element(0) as ObjectValue).obj;
}
else
{
refine_from = (overriding.value as ObjectValue).obj;
}
}
// Otherwise just refine_from Object
if (refine_from == null)
{
List <Object> st = parent.supertypes;
refine_from = st[st.Count - 1];
}
}
else
{
if (variable.supertypes.Contains(variable.parent) && parent.supertypes.Contains(variable.parent))
{
controlling_syntax = parent;
}
existing = parent.assigned_transitive(variable);
if (existing == null)
{
existing = variable.assigned(variable);
}
if (existing != null && existing.final) // Is Final
{
error("Cannot override final assignment " + parent.name + "." + variable.name + "=" + existing.ToString());
}
}
val = parse_value(controlling_syntax, refine_from);
}
return(parent.assign(variable, val, is_final));
}
return(null);
}
