//<过程调用语句> ::= call<标识符>
private void CallState(int level, List <LexicalAnalysis.SY> followSet)
{
Getsym();
if (tmpword.Sym == LexicalAnalysis.SY.IDSY)
{
int idx = symtable.Position(tmpword.token);
if (idx > 0)
{
SymbolTable.Item item = symtable.table[idx];
if (item.type == 2) //类型为子程序
{
Console.WriteLine(item.name + item.address);
ipt.AddPcode(Pcode.PC.CAL, level - item.level, item.address);
}
else
{
err.AddError(15, tmpword.LineID, tmpword.token); //call不能调用常量或者变量
}
}
else
{
err.AddError(11, tmpword.LineID, tmpword.token); //标识符未说明
}
Getsym();
}
else
{
err.AddError(14, tmpword.LineID, tmpword.token); //call后应为标识符
}
}
//ident赋值模块
private void IdentState(int level, List <LexicalAnalysis.SY> followSet)
{
int idx = symtable.Position(tmpword.token);
if (idx <= 0)
{
err.AddError(11, tmpword.LineID, tmpword.token); //标识符未说明
}
else if (symtable.table[idx].type != 1)
{
err.AddError(12, tmpword.LineID, tmpword.token); //赋值语句中，赋值号左部标识符属性应是变量
idx = -1;
}
Getsym();
if (tmpword.Sym == LexicalAnalysis.SY.ASSIGNSY)
{
Getsym();
}
else
{
err.AddError(13, tmpword.LineID, tmpword.token); // 赋值语句左部标识符后应是赋值运算符\":=\
}
Expression(level, followSet);
if (idx > 0)
{
SymbolTable.Item item = symtable.table[idx];
ipt.AddPcode(Pcode.PC.STO, level - item.level, item.address);
}
}
//read模块
private void ReadState(int level, List <LexicalAnalysis.SY> followSet)
{
Getsym();
if (tmpword.Sym == LexicalAnalysis.SY.LPARSY)
{
int idx = -1;
do
{
Getsym();
if (tmpword.Sym == LexicalAnalysis.SY.IDSY)
{
idx = symtable.Position(tmpword.token);
}
if (idx < 0)
{
err.AddError(11, tmpword.LineID, tmpword.token); //标识符未说明
}
else
{
SymbolTable.Item item = symtable.table[idx];
if (item.type == 1) //类型为变量
{
ipt.AddPcode(Pcode.PC.RED, level - item.level, item.address);
//ipt.AddPcode(Pcode.PC.STO, level - item.level, item.address);
}
else
{
err.AddError(31, tmpword.LineID, tmpword.token); // read括号内应该是变量标识符
}
}
Getsym();
} while (tmpword.Sym == LexicalAnalysis.SY.COMMASY);
}
else
{
err.AddError(40, tmpword.LineID, tmpword.token); // 应为左括号
}
if (tmpword.Sym == LexicalAnalysis.SY.RPARSY)
{
Getsym();
}
else
{
err.AddError(22, tmpword.LineID, tmpword.token); //表达式中漏掉右括号
}
}
//因子部分
private void Factor(int level, List <LexicalAnalysis.SY> followSet)
{
Test(factorPre, followSet, 24); //判断表达式开始符号
if (factorPre.Contains(tmpword.Sym) == true)
{
if (tmpword.Sym == LexicalAnalysis.SY.IDSY)
{
int idx = symtable.Position(tmpword.token);
if (idx >= 0)
{
SymbolTable.Item item = symtable.table[idx];
switch (item.type)
{
case 0: //取常量值于栈顶
ipt.AddPcode(Pcode.PC.LIT, 0, item.value);
break;
case 1: //取变量值于栈顶
ipt.AddPcode(Pcode.PC.LOD, level - item.level, item.address);
break;
case 2:
err.AddError(21, tmpword.LineID, tmpword.token); //表达式中不能有过程标识符
break;
}
}
else
{
err.AddError(11, tmpword.LineID, tmpword.token); //标识符未说明
}
Getsym();
}
else if (tmpword.Sym == LexicalAnalysis.SY.INTSY)
{
int num = int.Parse(tmpword.token);
ipt.AddPcode(Pcode.PC.LIT, 0, num);
Getsym();
}
else if (tmpword.Sym == LexicalAnalysis.SY.LPARSY) //左括号
{
Getsym();
List <LexicalAnalysis.SY> next = new List <LexicalAnalysis.SY>();
next.Clear();
next.AddRange(followSet);
next.Add(LexicalAnalysis.SY.RPARSY);
Expression(level, next);
if (tmpword.Sym == LexicalAnalysis.SY.RPARSY) //判断下一个符号是否为右括号
{
Getsym();
}
else
{
err.AddError(22, tmpword.LineID, tmpword.token);
}
}
List <LexicalAnalysis.SY> next1 = new List <LexicalAnalysis.SY>();
next1.Clear();
next1.Add(LexicalAnalysis.SY.LPARSY);
Test(followSet, next1, 23); //判断是否有非法符号
}
}