public void parser(List <token_table> list)
{
token_table token = getnexttoken(list);
if (token.token != "program")
{
error.Add("缺少关键字program");
}
token = getnexttoken(list);
if (token.type != 34)
{
error.Add("缺少程序名字");
}
token = getnexttoken(list);
if (token.token != ";")
{
error.Add("缺少';'");
}
token = getnexttoken(list);
if (token.token == "const")
{
con_st(list);
}
if (token.token == "var")
{
varst(list);
}
token = getnexttoken(list);
if (token.token == "begin")
{
ST_SORT(list);
}
}
private void ST_SORT(List <token_table> list)
{
token_table token = getnexttoken(list);
if (token.token == "if")
{
ifs(list); //if语句分析模块
}
else if (token.token == "while")
{
whiles(list); //while语句
}
else if (token.token == "repeat")
{
repeats(list); //repeat语句
}
else if (token.token == "for")
{
fors(list); //for语句
}
else
{
assign(list); //赋值语句
}
}
private token_table getnexttoken(List <token_table> list)
{
token_table token = new token_table(0, "", 0);
if (i < list.Count)
{
token = list[i];
i++;
}
return(token);
}
private void varst(List <token_table> list)
{
token_table token = getnexttoken(list);
while (true)
{
if (token.type != 34)
{
error.Add("行" + token.lineno + "\t语法错误:var之后不是标识符");
}
token = getnexttoken(list);
if (token.token == ",")
{
token = getnexttoken(list);
}
else if (token.token == ":")
{
break;
}
else
{
error.Add("行" + token.lineno + "\t错误:变量名后只能出现:和，");
}
}
token = getnexttoken(list);
if (token.token != "int" && token.token != "char" && token.token != "real" && token.token != "bool")
{
error.Add("行" + token.lineno + "\t错误:变量声明错误");
}
token = getnexttoken(list);
if (token.token != ";")
{
error.Add("行" + token.lineno + "\t错误:缺少;");
}
token = getnexttoken(list);
if (token.type == 34)
{
i--;
varst(list);
}
else if (token.token == "begin")
{
i--;
return;
}
else
{
error.Add("行" + token.lineno + "\t语法错误:缺少begin，或变量声明错误");
}
}
public void bexp(List <token_table> list)
{
bt(list);//单个布尔量
i--;
token_table token = getnexttoken(list);
if (token.token == "or")
{
bexp(list);
}
else
{
return;
}
}
private void bt(List <token_table> list)
{
bf(list);
i--;
token_table token = getnexttoken(list);
token = getnexttoken(list);
if (token.token == "and")
{
bexp(list);
}
else
{
return;
}
}
private void con_st(List <token_table> list)
{
token_table token = getnexttoken(list);
if (token.type == 34)
{
token = getnexttoken(list);
if (token.token == "=")
{
token = getnexttoken(list);
if (token.type >= 35 && token.type <= 39)
{
token = getnexttoken(list);
if (token.token == ";")
{
token = getnexttoken(list);
if (token.type == 34)
{
i--;
con_st(list);
}
else if (token.token == "var")
{
varst(list);
}
}
else
{
error.Add("行" + token.lineno + "\t错误:缺少';'");
}
}
else
{
error.Add("行" + token.lineno + "\t错误:'='后面必须跟常量");
}
}
else
{
error.Add("行" + token.lineno + "\t错误:标识符后面必须跟'='");
}
}
else
{
error.Add("行" + token.lineno + "\t错误:const后面必须跟标识符");
}
}
private void ifs(List <token_table> list)
{
bexp(list);
i--;
token_table token = getnexttoken(list);
if (token.token != "then")
{
error.Add("行" + token.lineno + "\t语法错误:缺少'then'");
}
ST_SORT(list);
token = getnexttoken(list);
if (token.token == "else")
{
ST_SORT(list);
}
}
private void assign(List <token_table> list)
{
i--;
token_table token = getnexttoken(list);
if (token.type == 34)
{
token = getnexttoken(list);
if (token.token == "=")
{
aexpr(list);
token = getnexttoken(list);
if (token.token != ";")
{
error.Add("行" + list[i - 1].lineno + "\t错误:缺少';'");
}
else
{
token = getnexttoken(list);
if (token.token == "end")
{
return;
}
else
{
i--;
ST_SORT(list);
}
}
}
else
{
error.Add("行" + token.lineno + "\t赋值语句错误:缺少'='");
}
}
else
{
error.Add("行" + token.lineno + "\t赋值语句错误:缺少变量");
}
}
private void aexpr(List <token_table> list)
{
token_table token = getnexttoken(list);
char state = '0';
while (state != '2')
{
switch (state)
{
case '0':
if (token.type >= 34 && token.type <= 39)
{
state = '1';
token = getnexttoken(list);
}
else
{
state = '2';
error.Add("行" + token.lineno + "\t错误:缺少常量");
}
break;
case '1':
if (isOperator(token.token))
{
state = '0';
token = getnexttoken(list);
}
else
{
state = '2';
i--;
}
break;
}
}
}
private void bf(List <token_table> list)
{
i--;
token_table token = getnexttoken(list);
if (token.token == "not")
{
bf(list);
}
else if (token.token == "(")
{
bexp(list);
token = getnexttoken(list);
if (token.token != ")")
{
error.Add("行" + token.lineno + "\t'（'不匹配");
}
else
{
aexpr(list);
token = getnexttoken(list);
if (token.token == ">" || token.token == ">=" || token.token == "<" || token.token == "<=" || token.token == "=" || token.token == "<>")
{
aexpr(list);
}
}
}
else
{
aexpr(list);
token = getnexttoken(list);
if (token.token == ">" || token.token == ">=" || token.token == "<" || token.token == "<=" || token.token == "=" || token.token == "<>")
{
aexpr(list);
}
}
}
private void con_st(token_table token)
{
throw new NotImplementedException();
}
