public override string ToString()
{
string text = "";
if (type_code == 1)
{
IdentifierStackElement e = (IdentifierStackElement)this;
text += "第" + e.linenum + "行标识符";
text += e.content;
}
else if (type_code == 2)
{
IntStackElement e = (IntStackElement)this;
text += "第" + e.linenum + "行整数";
text += e.content;
}
else if (type_code == 3)
{
NonterminalStackElement e = (NonterminalStackElement)this;
text += "非终结符";
text += e.name;
//递归调用
foreach (StackElement s in e.branches)
{
text += Environment.NewLine;
for (int i = 1; i < s.layers; i++)
{
text += " ";
}
text += s.ToString();
}
}
else if (type_code == 4)
{
OtherTerminalStackElement e = (OtherTerminalStackElement)this;
text += "第" + e.linenum + "行终结符";
text += e.content;
}
else if (type_code == 5)
{
RealStackElement e = (RealStackElement)this;
text += "第" + e.linenum + "行实数";
text += e.content;
}
else if (type_code == 7)
{
CharStackElement e = (CharStackElement)this;
text += "第" + e.linenum + "行字符";
text += e.content;
}
else if (type_code == 8)
{
StringStackElement e = (StringStackElement)this;
text += "第" + e.linenum + "行字符串";
text += e.content;
}
else
{
StateStackElement e = (StateStackElement)this;
text += "状态" + e.state;
}
return(text);
}
//这里情况就不同了，上面是对应着+-*/四则运算的，所以char/string/数组 都不应该直接进行这些运算，但是他们可以被访问赋值，因此这里不做过多限制
/*
* factor→+factor |-factor|number|identifier more_identifier|(expr)|"string"|'char'
* more_identifier→ ε | [simple_expr] | () | (param_values)
* number→real_number |integer
*/
public static Value eval_factor(NonterminalStackElement factor_node, List <Dictionary <string, Value> > bindings_stack)
{
StackElement first_child = (StackElement)factor_node.branches[0];
//factor → number | "string" | 'char'
if (factor_node.branches.Count == 1)
{
//char
if (first_child.type_code == 7)
{
CharStackElement char_node = (CharStackElement)first_child;
return(new CharValue("char", true, char_node.content, char_node.linenum));
}
//string
else if (first_child.type_code == 8)
{
StringStackElement string_node = (StringStackElement)first_child;
return(new StringValue("string", true, string_node.content, string_node.linenum));
}
//number
else if (first_child.type_code == 3)
{
NonterminalStackElement number_node = (NonterminalStackElement)first_child;
return(eval_number(number_node));
}
else
{
throw new ExecutorException("eval_factor运行中发现factor文法发生了意想不到的变化");
}
}
//factor→+factor |-factor | identifier more_identifier
else if (factor_node.branches.Count == 2)
{
//+ - factor
if (first_child.type_code == 4)
{
int linenum = ((OtherTerminalStackElement)first_child).linenum;
OtherTerminalStackElement positive_or_negative = (OtherTerminalStackElement)first_child;
NonterminalStackElement child_factor_node = (NonterminalStackElement)factor_node.branches[1];
if (positive_or_negative.content == "+")
{
return(eval_factor(child_factor_node, bindings_stack));
}
//负号就要把值的符号颠倒
else
{
Value child_factor_node_value = eval_factor(child_factor_node, bindings_stack);
if (!Value.computable_types.Contains(child_factor_node_value.type))
{
throw new ExecutorException("不可在非数值类型前加上正号或者负号", linenum);
}
if (child_factor_node_value.type == "real")
{
RealValue value = (RealValue)child_factor_node_value;
value.value = -value.value;
return(value);
}
else if (child_factor_node_value.type == "int")
{
IntValue value = (IntValue)child_factor_node_value;
value.value = -value.value;
return(value);
}
else if (child_factor_node_value.type == "number")
{
NumberValue value = (NumberValue)child_factor_node_value;
value.value = -value.value;
return(value);
}
else
{
throw new ExecutorException("eval_factor运行中发现factor文法发生了意想不到的变化");
}
}
}
//factor→ identifier more_identifier
// more_identifier→ε | [simple_expr] | () | (param_values)
else
{
IdentifierStackElement identifier_node = (IdentifierStackElement)factor_node.branches[0];
int linenum = identifier_node.linenum;
NonterminalStackElement more_identifier_node = (NonterminalStackElement)factor_node.branches[1];
//检查是否定义
Dictionary <string, Value> bindings = ExecutorTools.findBindings(bindings_stack, identifier_node.content);
if (bindings != null)
{
//只是访问一个identifier 即 factor→ identifier
// more_identifier→ε
if (more_identifier_node.branches.Count == 0)
{
Value identifier_value = bindings[identifier_node.content];
return(identifier_value);
}
//应该是调用了一个不接受任何参数的函数比如foo()这样， more_identifier→ ()
else if (more_identifier_node.branches.Count == 2)
{
Value identifier_value = bindings[identifier_node.content];
if (identifier_value.type != "func")
{
throw new ExecutorException("标识符后带()应该是调用函数，但该标识符" + identifier_node.content + "对应函数并不存在", linenum);
}
FuncValue relevant_fucntion = (FuncValue)identifier_value;
Value return_value = relevant_fucntion.executeFunction();
return(return_value);
}
// 应该是调用了一个带参数的函数，或者是访问数组的某个元素 more_identifier → [simple_expr] | (param_values)
else if (more_identifier_node.branches.Count == 3)
{
Value identifier_value = bindings[identifier_node.content];
NonterminalStackElement second_element = (NonterminalStackElement)more_identifier_node.branches[1];
// more_identifier → [simple_expr] 要检查：第一，数组访问越界了没有；第二，访问的数组元素类型是否与要求的类型type相符合
if (second_element.name == "simple_expr")
{
//类型错误
if (!identifier_value.type.Contains("Array"))
{
throw new ExecutorException("标识符后带[ ]应该是访问数组某个元素，但该标识符" + identifier_node.content + "对应的并不是数组", linenum);
}
string array_type = identifier_value.type.Substring(0, identifier_value.type.Length - 5);
NonterminalStackElement simple_expr_node = second_element;
int index_to_access = ExecutorTools.get_array_len_from_simple_expr(simple_expr_node, bindings_stack);
//越界错误
if (index_to_access >= identifier_value.getArrayLen())
{
throw new ExecutorException("访问数组" + identifier_node.content + "时出现越界访问错误，数组长度只有" + identifier_value.getArrayLen(), linenum);
}
//eval要求就是获取到值，所以这里直接获取数组中元素的值，再转换为Value类型
else
{
if (identifier_value.type.Contains("int"))
{
return(new IntValue("int", false, identifier_value.getIntArrayElement(index_to_access).ToString(), linenum));
}
else if (identifier_value.type.Contains("real"))
{
return(new RealValue("real", false, identifier_value.getRealArrayElement(index_to_access).ToString(), linenum));
}
else if (identifier_value.type.Contains("int"))
{
return(new CharValue("char", false, identifier_value.getCharArrayElement(index_to_access).ToString(), linenum));
}
else
{
return(new StringValue("string", false, identifier_value.getStringArrayElement(index_to_access).ToString(), linenum));
}
}
}
// more_identifier → (param_values) 要检查：第一，函数签名是否符合（类型，次序）；第二，函数返回类型是否与要求的类型type相符合
else if (second_element.name == "param_values")
{
//类型错误
if (!identifier_value.type.Contains("func"))
{
throw new ExecutorException(identifier_node.content + "对应的并不是函数，无法调用", linenum);
}
FuncValue func_value = (FuncValue)identifier_value;
List <Value> args = new List <Value>();
NonterminalStackElement expr_node;
//param_values →expr,param_values|expr
NonterminalStackElement param_values_node = second_element;
while (param_values_node.branches.Count == 3)
{
expr_node = (NonterminalStackElement)param_values_node.branches[0];
param_values_node = (NonterminalStackElement)param_values_node.branches[2];
args.Add(eval_expr(expr_node, bindings_stack));
}
expr_node = (NonterminalStackElement)param_values_node.branches[0];
args.Add(eval_expr(expr_node, bindings_stack));
return(ExecutorTools.executeFunction(func_value, args, linenum));
}
else
{
throw new ExecutorException("文法发生了变化", linenum);
}
}
else
{
//Value relevant_value = Frame.curr_frame.local_bindings[identifier_node.content];
throw new ExecutorException("怎么到这的？", linenum);
}
}
throw new ExecutorException("语句中访问未定义的标识符" + identifier_node.content, linenum);
}
}
//factor→ ( expr )
else if (factor_node.branches.Count == 3)
{
NonterminalStackElement expr_node = (NonterminalStackElement)factor_node.branches[1];
return(eval_expr(expr_node, bindings_stack));
}
else
{
throw new ExecutorException("文法发生了变化", factor_node.linenum);
}
}
private void recursiveAddNodes(StackElement e, TreeViewItem newItem)
{
try
{
if (e.type_code == 6)
{
throw new ParserException("这个表示状态的栈元素不应该出现在Tree的递归子结点中！");
}
else if (e.type_code == 1)
{
IdentifierStackElement ele = (IdentifierStackElement)e;
newItem.Header = "第" + ele.linenum + "行的标识符：" + ele.content;
}
else if (e.type_code == 2)
{
IntStackElement ele = (IntStackElement)e;
newItem.Header = "第" + ele.linenum + "行的整数：" + ele.content;
}
else if (e.type_code == 3)
{
NonterminalStackElement ele = (NonterminalStackElement)e;
newItem.Header = "非终结符：" + ele.name;
}
else if (e.type_code == 4)
{
OtherTerminalStackElement ele = (OtherTerminalStackElement)e;
newItem.Header = "第" + ele.linenum + "行的终结符：" + ele.content;
}
else if (e.type_code == 5)
{
RealStackElement ele = (RealStackElement)e;
newItem.Header = "第" + ele.linenum + "行的实数：" + ele.content;
}
else if (e.type_code == 7)
{
CharStackElement ele = (CharStackElement)e;
newItem.Header = "第" + ele.linenum + "行的字符：" + ele.content;
}
else if (e.type_code == 8)
{
StringStackElement ele = (StringStackElement)e;
newItem.Header = "第" + ele.linenum + "行的字符串：" + ele.content;
}
else
{
throw new ParserException("这是啥栈元素？");
}
//若是终结符，branches就是空，若不是非终结符，它也终究会走到末端叶子节点，也就是非终结符，然后递归终止
if (e.branches.Count != 0)
{
foreach (StackElement ele in e.branches)
{
TreeViewItem new_node = new TreeViewItem();
newItem.Items.Add(new_node);
recursiveAddNodes(ele, new_node);
}
}
}
catch (ParserException pe)
{
MessageBox.Show(pe.err_msg);
}
catch (Exception ee)
{
MessageBox.Show(ee.ToString());
}
}