1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
|
#include "parser.ih"
NonTerminal *Parser::requireNonTerminal(string const &name)
{
string stype;
Symbol *sp = d_symtab.lookup(name);
if (sp)
{
if (sp->isNonTerminal()) // Only ok if already defined
return NonTerminal::downcast(sp); // as non-terminal
if (sp->isUndetermined()) // assumed terminal earlier,
{ // turns out to be nonterm.
stype = sp->sType();
d_symtab.erase(d_symtab.find(name));
// now all occurrences of the terminal in existing production rules
// must be changed into nonterminals. Also, sp must be removed from rule's
// terminal vector d_terminal
}
else
{
multiplyDefined(sp);
return 0;
}
}
NonTerminal *np = new NonTerminal(name, stype);
// If not yet defined, define
// it now as a non-terminal
d_symtab.insert
(
Symtab::value_type
(
name,
d_rules.insert(np)
)
);
if (sp)
d_rules.termToNonterm(sp, np);
return np;
}
|
