public ParserReduce(ParserAction action,int depth,Production prod) : base(action) {m_depth=depth; m_prod = prod; }
public bool Lookback(Production pr,ParseState p) { return new Path(this,pr.Prefix(pr.m_rhs.Count)).Top==this; }
public ProdItem(Production prod, int pos)
{
m_prod=prod;
m_pos=pos;
m_done=false;
}
public Precedence.PrecType ShiftPrecedence(Production prod,ParseState ps) // 4.5h
{
if (prod==null) // no reduce available
return Precedence.PrecType.left; // shift // 4.5h
if (!((SymbolSet)prod.m_lhs.m_follow).Contains(this)) // if this is not a follow symbol of the prod's lhs, there is no conflict
return Precedence.PrecType.left; // shift // 4.5h
if (m_prec==null)
{ // no precedence information
Console.WriteLine("Shift/Reduce conflict {0} on reduction {1} in state {2}", yytext, prod.m_pno,ps.m_state);
return Precedence.PrecType.left; // shift anyway // 4.5h
}
if (m_prec.m_type==Precedence.PrecType.nonassoc) // 4.5h
return Precedence.PrecType.nonassoc; // 4.5h
int p = Precedence.Check(this,prod,0);
if (p==0)
{
if (Precedence.Check(m_prec,Precedence.PrecType.right,0)!=0)
{ // equal precedence but right associative: shift
return Precedence.PrecType.left; // 4.5h
}
return Precedence.PrecType.right; // don't shift // 4.5h
}
return (p>0)?Precedence.PrecType.left:Precedence.PrecType.right; // shift if symbol has higher precedence than production, else reduce // 4.5h
}
public static void Check(Production p)
{
int efflen = p.m_rhs.Count;
while (efflen>1 && ((CSymbol)p.m_rhs[efflen-1]).IsAction())
efflen--;
if (efflen==3)
{
CSymbol op = (CSymbol)p.m_rhs[1];
int b = CheckType(op.m_prec, PrecType.left, 0);
if (b!=0 && ((CSymbol)p.m_rhs[2])==p.m_lhs)
// allow operators such as E : V = E here
p.m_prec = b;
}
else if (efflen==2)
{
if ((CSymbol)p.m_rhs[0]==p.m_lhs)
{
int aft = Check(((CSymbol)p.m_rhs[1]).m_prec, PrecType.after,0);
if (aft!=0)
p.m_prec = aft;
}
else if ((CSymbol)p.m_rhs[1]==p.m_lhs)
{
int bef = Check(((CSymbol)p.m_rhs[0]).m_prec, PrecType.before,0);
if (bef!=0)
p.m_prec = bef;
}
}
}
public static int Check(CSymbol s, Production p, int d)
{
if (s.m_prec==null)
return 0;
int a = CheckType(s.m_prec, PrecType.after,d+1);
int b = CheckType(s.m_prec, PrecType.left,d+1);
if (a>b)
return a - p.m_prec;
else
return b - p.m_prec;
}
/// <exclude/>
public ProdItem()
{
m_prod = null;
m_pos = 0;
m_done=false;
}