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()); } }