//条件部分
private void Condition(int level, List <LexicalAnalysis.SY> followSet)
{
if (tmpword.Sym == LexicalAnalysis.SY.ODDSY)
{
Getsym();
Expression(level, followSet);
ipt.AddPcode(Pcode.PC.OPR, 0, 6); //OPR 0 6;栈顶元素的奇偶判断
}
else
{
List <LexicalAnalysis.SY> next = new List <LexicalAnalysis.SY>();
next.Clear();
next.AddRange(followSet);
next.Add(LexicalAnalysis.SY.EQUSY);
next.Add(LexicalAnalysis.SY.UNEQUSY);
next.Add(LexicalAnalysis.SY.LESSSY);
next.Add(LexicalAnalysis.SY.LESY);
next.Add(LexicalAnalysis.SY.GRTSY);
next.Add(LexicalAnalysis.SY.GESY);
Expression(level, next);
//当前符号是否为=,<>,<,<=,>,>=中的一种
if (tmpword.Sym == LexicalAnalysis.SY.EQUSY || tmpword.Sym == LexicalAnalysis.SY.UNEQUSY || tmpword.Sym == LexicalAnalysis.SY.LESSSY ||
tmpword.Sym == LexicalAnalysis.SY.LESY || tmpword.Sym == LexicalAnalysis.SY.GRTSY || tmpword.Sym == LexicalAnalysis.SY.GESY)
{
LexicalAnalysis.SY op = tmpword.Sym;
Getsym();
Expression(level, followSet);
ipt.AddPcode(Pcode.PC.OPR, 0, GetOperator(op));
}
else
{
err.AddError(20, tmpword.LineID, tmpword.token);
}
}
}
//项部分
private void Term(int level, List <LexicalAnalysis.SY> followSet)
{
List <LexicalAnalysis.SY> next = new List <LexicalAnalysis.SY>();
next.Clear();
next.AddRange(followSet);
next.Add(LexicalAnalysis.SY.STARSY);
next.Add(LexicalAnalysis.SY.DIVISY);
Factor(level, next);
while (tmpword.Sym == LexicalAnalysis.SY.STARSY || tmpword.Sym == LexicalAnalysis.SY.DIVISY)
{
LexicalAnalysis.SY op = tmpword.Sym;
Getsym();
Factor(level, next);
ipt.AddPcode(Pcode.PC.OPR, 0, GetOperator(op));
}
}
//表达式部分
private void Expression(int level, List <LexicalAnalysis.SY> followSet)
{
if (tmpword.Sym == LexicalAnalysis.SY.PLUSSY || tmpword.Sym == LexicalAnalysis.SY.MINUSSY)
{
LexicalAnalysis.SY op = tmpword.Sym;
Getsym();
List <LexicalAnalysis.SY> next = new List <LexicalAnalysis.SY>();
next.Clear();
next.AddRange(followSet);
next.Add(LexicalAnalysis.SY.PLUSSY);
next.Add(LexicalAnalysis.SY.MINUSSY);
Term(level, next);
if (op == LexicalAnalysis.SY.MINUSSY)
{
ipt.AddPcode(Pcode.PC.OPR, 0, 1); //OPR 0 1;栈顶元素取反
}
}
else
{
List <LexicalAnalysis.SY> next = new List <LexicalAnalysis.SY>();
next.Clear();
next.AddRange(followSet);
next.Add(LexicalAnalysis.SY.PLUSSY);
next.Add(LexicalAnalysis.SY.MINUSSY);
Term(level, next);
}
while (tmpword.Sym == LexicalAnalysis.SY.PLUSSY || tmpword.Sym == LexicalAnalysis.SY.MINUSSY)
{
LexicalAnalysis.SY op = tmpword.Sym;
Getsym();
List <LexicalAnalysis.SY> next = new List <LexicalAnalysis.SY>();
next.Clear();
next.AddRange(followSet);
next.Add(LexicalAnalysis.SY.PLUSSY);
next.Add(LexicalAnalysis.SY.MINUSSY);
Term(level, next);
ipt.AddPcode(Pcode.PC.OPR, 0, GetOperator(op));
}
}
//转换为pcode中对应的操作码值
private int GetOperator(LexicalAnalysis.SY x)
{
switch (x)
{
case LexicalAnalysis.SY.PLUSSY:
return(2);
case LexicalAnalysis.SY.MINUSSY:
return(3);
case LexicalAnalysis.SY.STARSY:
return(4);
case LexicalAnalysis.SY.DIVISY:
return(5);
case LexicalAnalysis.SY.EQUSY:
return(8);
case LexicalAnalysis.SY.UNEQUSY:
return(9);
case LexicalAnalysis.SY.LESSSY:
return(10);
case LexicalAnalysis.SY.GESY:
return(11);
case LexicalAnalysis.SY.GRTSY:
return(12);
case LexicalAnalysis.SY.LESY:
return(13);
}
return(0);
}
