//logical_expr→relational_expr logical_expr_more
// logical_expr_more→ ε | logical_op relational_expr logical_expr_more
public static Value eval_logical_expr(NonterminalStackElement logical_expr_node, List <Dictionary <string, Value> > bindings_stack)
{
if (logical_expr_node.branches.Count != 2)
{
throw new ExecutorException("文法发生了变化", logical_expr_node.linenum);
}
else
{
NonterminalStackElement relational_expr_node = (NonterminalStackElement)logical_expr_node.branches[0];
NonterminalStackElement logical_expr_more_node = (NonterminalStackElement)logical_expr_node.branches[1];
Value first_relational_expr_value = eval_relational_expr(relational_expr_node, bindings_stack);
//逐个迭代，很自然的左结合
while (logical_expr_more_node.branches.Count == 3)
{
NonterminalStackElement logical_op_node = (NonterminalStackElement)logical_expr_more_node.branches[0];
NonterminalStackElement second_relational_expr_node = (NonterminalStackElement)logical_expr_more_node.branches[1];
OtherTerminalStackElement logical_op = (OtherTerminalStackElement)logical_op_node.branches[0];
if (logical_op.content == "&&")
{
//short circuit evaluation短路求值
if (!first_relational_expr_value.getBoolean())
{
return(new BoolValue("bool", true, false, logical_op.linenum));
}
//短路求值！
Value second_relational_expr_value = eval_relational_expr(second_relational_expr_node, bindings_stack);
first_relational_expr_value = new BoolValue("bool", true, second_relational_expr_value.getBoolean(), logical_op.linenum);
}
else
{
//short circuit evaluation短路求值
if (first_relational_expr_value.getBoolean())
{
return(new BoolValue("bool", true, true, logical_op.linenum));
}
//短路求值！
Value second_relational_expr_value = eval_relational_expr(second_relational_expr_node, bindings_stack);
first_relational_expr_value = new BoolValue("bool", true, second_relational_expr_value.getBoolean(), logical_op.linenum);
}
logical_expr_more_node = (NonterminalStackElement)logical_expr_more_node.branches[2];
}
return(first_relational_expr_value);
}
}
//falsey的几种情况，根据C语言测试： \0的char类型，0的int/real，然后我再加一条string为""时，数组均返回true
public bool getBoolean()
{
if (type == "char")
{
CharValue v = (CharValue)this;
return(v.value != "\0");
}
else if (type == "string")
{
StringValue v = (StringValue)this;
return(v.value != "");
}
else if (type == "int")
{
IntValue v = (IntValue)this;
return(v.value != 0);
}
else if (type == "real")
{
RealValue v = (RealValue)this;
return(v.value != 0);
}
else if (type.Contains("Array"))
{
return(true);
}
else if (type == "func")
{
throw new ExecutorException("类型错误，出现了错误的类型：函数", line_num);
}
else if (type == "bool")
{
BoolValue v = (BoolValue)this;
return(v.value);
}
else
{
throw new ExecutorException("文法发生了变化", line_num);
}
}
internal static void write_value(Value v, int linenum)
{
if (v.type == "int")
{
IntValue value = (IntValue)v;
MessageBox.Show(value.value.ToString());
}
else if (v.type == "real")
{
RealValue value = (RealValue)v;
MessageBox.Show(value.value.ToString());
}
else if (v.type == "number")
{
NumberValue value = (NumberValue)v;
MessageBox.Show(value.value.ToString());
}
else if (v.type == "char")
{
CharValue value = (CharValue)v;
MessageBox.Show(value.value);
}
else if (v.type == "string")
{
StringValue value = (StringValue)v;
MessageBox.Show(value.value);
}
else if (v.type == "bool")
{
BoolValue value = (BoolValue)v;
MessageBox.Show(value.value.ToString());
}
else if (v.type == "intArray")
{
IntArrayValue value = (IntArrayValue)v;
string text = "";
for (int i = 0; i < value.array_elements.Length; i++)
{
text += value.array_elements[i];
text += "|";
}
MessageBox.Show(text);
}
else if (v.type == "realArray")
{
RealArrayValue value = (RealArrayValue)v;
string text = "";
for (int i = 0; i < value.array_elements.Length; i++)
{
text += value.array_elements[i];
text += "|";
}
MessageBox.Show(text);
}
else if (v.type == "charArray")
{
CharArrayValue value = (CharArrayValue)v;
string text = "";
for (int i = 0; i < value.array_elements.Length; i++)
{
text += value.array_elements[i];
text += "|";
}
MessageBox.Show(text);
}
else if (v.type == "stringArray")
{
StringArrayValue value = (StringArrayValue)v;
string text = "";
for (int i = 0; i < value.array_elements.Length; i++)
{
text += value.array_elements[i];
text += "|";
}
MessageBox.Show(text);
}
else
{
throw new ExecutorException("出现了没有考虑到的新类型", linenum);
}
}
//因为3>2>0这里3>2会evaluate成1
public IntValue compareWith(Value v, string op = "")
{
//直接比较是否相等
if (op == "")
{
if (this.type != v.type)
{
if (type == "int" && v.type == "number")
{
IntValue v1 = (IntValue)this;
NumberValue v2 = (NumberValue)v;
if (v1.value == v2.value)
{
return(new IntValue("int", true, "1", line_num));
}
else
{
return(new IntValue("int", true, "0", line_num));
}
}
else if (type == "real" && v.type == "number")
{
RealValue v1 = (RealValue)this;
NumberValue v2 = (NumberValue)v;
if (v1.value == v2.value)
{
return(new IntValue("int", true, "1", line_num));
}
else
{
return(new IntValue("int", true, "0", line_num));
}
}
else if (type == "number" && v.type == "int")
{
NumberValue v1 = (NumberValue)this;
IntValue v2 = (IntValue)v;
if (v1.value == v2.value)
{
return(new IntValue("int", true, "1", line_num));
}
else
{
return(new IntValue("int", true, "0", line_num));
}
}
else if (type == "number" && v.type == "real")
{
NumberValue v1 = (NumberValue)this;
RealValue v2 = (RealValue)v;
if (v1.value == v2.value)
{
return(new IntValue("int", true, "1", line_num));
}
else
{
return(new IntValue("int", true, "0", line_num));
}
}
else if (type == "int" && v.type == "real")
{
IntValue v1 = (IntValue)this;
RealValue v2 = (RealValue)v;
if (v1.value == v2.value)
{
return(new IntValue("int", true, "1", line_num));
}
else
{
return(new IntValue("int", true, "0", line_num));
}
}
else if (type == "real" && v.type == "int")
{
RealValue v1 = (RealValue)this;
IntValue v2 = (IntValue)v;
if (v1.value == v2.value)
{
return(new IntValue("int", true, "1", line_num));
}
else
{
return(new IntValue("int", true, "0", line_num));
}
}
else
{
//类型不同比较直接不同
return(new IntValue("int", true, "0", line_num));
}
}
else
{
if (type == "int")
{
IntValue v1 = (IntValue)this;
IntValue v2 = (IntValue)v;
if (v1.value == v2.value)
{
return(new IntValue("int", true, "1", line_num));
}
else
{
return(new IntValue("int", true, "0", line_num));
}
}
else if (type == "real")
{
RealValue v1 = (RealValue)this;
RealValue v2 = (RealValue)v;
if (v1.value == v2.value)
{
return(new IntValue("int", true, "1", line_num));
}
else
{
return(new IntValue("int", true, "0", line_num));
}
}
else if (type == "char")
{
CharValue v1 = (CharValue)this;
CharValue v2 = (CharValue)v;
if (v1.value == v2.value)
{
return(new IntValue("int", true, "1", line_num));
}
else
{
return(new IntValue("int", true, "0", line_num));
}
}
else if (type == "string")
{
StringValue v1 = (StringValue)this;
StringValue v2 = (StringValue)v;
if (v1.value == v2.value)
{
return(new IntValue("int", true, "1", line_num));
}
else
{
return(new IntValue("int", true, "0", line_num));
}
}
else if (type == "bool")
{
BoolValue v1 = (BoolValue)this;
BoolValue v2 = (BoolValue)v;
if (v1.value == v2.value)
{
return(new IntValue("int", true, "1", line_num));
}
else
{
return(new IntValue("int", true, "0", line_num));
}
}
else
{
throw new ExecutorException("暂不实现数组类型比较", line_num);
}
}
}
//若是大小比较，那么就只有real/int这些number可以compare，其他的不能
else if (computable_types.Contains(v.type) && computable_types.Contains(type))
{
double v1 = 0, v2 = 0;
bool result;
if (type == "int")
{
v1 = ((IntValue)this).value;
}
else if (type == "real")
{
v1 = ((RealValue)this).value;
}
else
{
v1 = ((NumberValue)this).value;
}
if (v.type == "int")
{
v2 = ((IntValue)v).value;
}
else if (v.type == "real")
{
v2 = ((RealValue)v).value;
}
else
{
v2 = ((NumberValue)v).value;
}
if (op == ">")
{
result = v1 > v2;
}
else if (op == "<")
{
result = v1 < v2;
}
else if (op == ">=")
{
result = v1 >= v2;
}
else if (op == "<=")
{
result = v1 <= v2;
}
else
{
throw new ExecutorException("出现了文法中未定义的判断符" + op, line_num);
}
if (result)
{
return(new IntValue("int", true, "1", line_num));
}
else
{
return(new IntValue("int", true, "0", line_num));
}
}
else
{
throw new ExecutorException("无法直接比较大小的类型", line_num);
}
}