public BinaryExpression(ExpSyntaxTree left_, Token op_, ExpSyntaxTree right_)
{
left = left_;
op = op_;
right = right_;
_line = op_.m_line;
}
TableAccess ParseTableAccessor(ExpSyntaxTree table)
{
NextToken();// skip '[' or '.'
var index_access = new TableAccess(_current.m_line);
index_access.table = table;
if (_current.m_type == (int)'[')
{
index_access.index = ParseExp();
if (NextToken().m_type != (int)']')
{
throw NewParserException("expect ']'", _current);
}
}
else
{
if (!NextToken().IsLiteralString())
{
throw NewParserException("expect <id> after '.'", _current);
}
index_access.index = new Terminator(_current.ConvertToStringToken());
}
return(index_access);
}
FuncCall ParseFunctionCall(ExpSyntaxTree caller)
{
Debug.Assert(LookAhead().Match('('));// 基本的函数调用只支持语法 f(arg,...)，后面可以安排写语法糖什么的。
var func_call = new FuncCall(LookAhead().m_line);
func_call.caller = caller;
func_call.args = ParseArgs();
return(func_call);
}
ExpSyntaxTree ParseTailExp(ExpSyntaxTree exp)
{
// table index or func call
for (; ;)
{
if (LookAhead().Match('[') || LookAhead().Match('.'))
{
exp = ParseTableAccessor(exp);
}
else if (LookAhead().Match('('))
{
exp = ParseFunctionCall(exp);
}
else
{
break;
}
}
return(exp);
}
SyntaxTree ParseOtherStatement()
{
// 没什么限制，基本可以随意写些MainExp
// 重点处理的是一些赋值类语句，赋值类语句的左值必须是var类型的
// SS还增加几个语法支持，+=，-=，++，--
if (IsMainExpNext() == false)
{
return(null);
}
ExpSyntaxTree exp = ParseMainExp();
if (LookAhead().Match('=') || LookAhead().Match(','))
{
// assign statement
if (!IsVar(exp))
{
throw NewParserException("expect var for assign statement", _current);
}
var assign_statement = new AssignStatement(LookAhead().m_line);
assign_statement.var_list.Add(exp);
while (LookAhead().m_type != (int)'=')
{
if (NextToken().m_type != (int)',')
{
throw NewParserException("expect ',' to split var-list", _current);
}
if (LookAhead().m_type != (int)TokenType.NAME)
{
throw NewParserException("expect 'id' to start var", _look_ahead);
}
exp = ParseMainExp();
if (!IsVar(exp))
{
throw NewParserException("expect var for assign statement", _current);
}
assign_statement.var_list.Add(exp);
}
NextToken();// skip '='
assign_statement.exp_list = ParseExpList();
return(assign_statement);
}
var type = (TokenType)LookAhead().m_type;
if (SpecialAssginStatement.NeedWork(type))
{
if (!IsVar(exp))
{
throw NewParserException("expect var here", _current);
}
var special_statement = new SpecialAssginStatement(_current.m_line);
special_statement.var = exp;
special_statement.op = type;
if (SpecialAssginStatement.IsSelfMode(type))
{
special_statement.exp = ParseExp();
}
return(special_statement);
}
return(exp);// 不限制了
}
