//执行某个具体的stmt，
// stmt → if_stmt| while_stmt|read_stmt| write_stmt|assign_stmt|declare_stmt| →compound_stmt|return_stmt|expr_stmt
// while_substmt →while_if_stmt| while_stmt|read_stmt| write_stmt|assign_stmt|declare_stmt| →while_compound_stmt|return_stmt|expr_stmt | break_stmt | continue_stmt
// 有三种可能，return了一个值，return;，或者真的没有return语句，分别对应Value，NullValue，Null
private static Value executeStmt(NonterminalStackElement specific_stmt_node, List <Dictionary <string, Value> > binding_stack)
{
string message = "";
//if_stmt→if(expr)compound_stmt more_ifelse
if (specific_stmt_node.name == "if_stmt")
{
NonterminalStackElement expr_node = (NonterminalStackElement)specific_stmt_node.branches[2];
Value expr_value = Evaluator.eval_expr(expr_node, binding_stack);
if (expr_value.getBoolean())
{
NonterminalStackElement compound_stmt = (NonterminalStackElement)specific_stmt_node.branches[4];
return(executeStmt(compound_stmt, binding_stack));
}
else
{
//more_ifelse→ε|else else_stmt
NonterminalStackElement more_if_else_node = (NonterminalStackElement)specific_stmt_node.branches[5];
if (more_if_else_node.branches.Count == 0)
{
return(null);
}
else
{
//else_stmt→if_stmt|compound_stmt
NonterminalStackElement else_stmt = (NonterminalStackElement)more_if_else_node.branches[1];
NonterminalStackElement specific_else_stmt = (NonterminalStackElement)else_stmt.branches[0];
return(executeStmt(specific_else_stmt, binding_stack));
}
}
//emmm突然优雅起来了？？？
}
//while_stmt→while(expr) while_compound_stmt
else if (specific_stmt_node.name == "while_stmt")
{
NonterminalStackElement expr_node = (NonterminalStackElement)specific_stmt_node.branches[2];
Value expr_value = Evaluator.eval_expr(expr_node, binding_stack);
Dictionary <string, Value> new_bindings = new Dictionary <string, Value>();
binding_stack.Add(new_bindings);
Executor.while_indexes.Add(binding_stack.Count);
//while_compound_stmt→{while_stmt_lst}|{}
//while_stmt_lst →while_substmt while_stmt_lst | while_substmt
NonterminalStackElement while_compound_stmt_node = (NonterminalStackElement)specific_stmt_node.branches[4];
while (expr_value.getBoolean())
{
if (while_compound_stmt_node.branches.Count == 2)
{
//do nothing
}
//while_compound_stmt→{while_stmt_lst}
else
{
NonterminalStackElement while_stmt_lst_node = (NonterminalStackElement)while_compound_stmt_node.branches[1];
Value v = executeStmtLst(while_stmt_lst_node, binding_stack);
//若提前执行return语句，直接结束while循环
if (v != null)
{
binding_stack.RemoveAt(binding_stack.Count - 1);
return(v);
}
}
expr_value = Evaluator.eval_expr(expr_node, binding_stack);
}
binding_stack.RemoveAt(binding_stack.Count - 1);
return(null);
}
//read_stmt→read identifier;| read identifier [ simple_expr ] ;
else if (specific_stmt_node.name == "read_stmt")
{
IdentifierStackElement identifier_node = (IdentifierStackElement)specific_stmt_node.branches[1];
if (specific_stmt_node.branches.Count == 3)
{
Dictionary <string, Value> bindings = findBindings(binding_stack, identifier_node.content);
if (bindings != null)
{
string type = bindings[identifier_node.content].type;
if (type.Contains("func") || type.Contains("bool"))
{
throw new ExecutorException("请检查您的读入目标是否有误，不可读入函数或者布尔类型值", specific_stmt_node.linenum);
}
else if (type.Contains("Array"))
{
int len = bindings[identifier_node.content].getArrayLen();
bindings[identifier_node.content] = ReaderHelper.read_array_value(type, identifier_node.linenum, len);
}
else
{
bindings[identifier_node.content] = ReaderHelper.read_single_value(type, identifier_node.linenum);
}
}
else
{
throw new ExecutorException("未定义的标识符" + identifier_node.content, identifier_node.linenum);
}
}
else
{
Dictionary <string, Value> bindings = findBindings(binding_stack, identifier_node.content);
if (bindings != null)
{
string type = bindings[identifier_node.content].type;
if (!type.Contains("Array"))
{
throw new ExecutorException("请检查您的读入目标是否有误，该标识符并不对应数组", specific_stmt_node.linenum);
}
NonterminalStackElement simple_expr_node = (NonterminalStackElement)specific_stmt_node.branches[3];
int index = get_array_len_from_simple_expr(simple_expr_node, binding_stack);
type = type.Substring(0, type.Length - 5);
Value read_value = ReaderHelper.read_single_value(type, identifier_node.linenum);
bindings[identifier_node.content].changeValueOfArray(index, read_value.getString());
}
else
{
throw new ExecutorException("未定义的标识符" + identifier_node.content, identifier_node.linenum);
}
}
return(null);
}
//write_stmt→write expr;
else if (specific_stmt_node.name == "write_stmt")
{
NonterminalStackElement expr_node = (NonterminalStackElement)specific_stmt_node.branches[1];
Value v = Evaluator.eval_expr(expr_node, binding_stack);
if (v.type == "func")
{
throw new ExecutorException("不支持write函数", specific_stmt_node.linenum);
}
WriterHelper.write_value(v, specific_stmt_node.linenum);
return(null);
}
//assign_stmt→identifier other_assign
else if (specific_stmt_node.name == "assign_stmt")
{
IdentifierStackElement identifier_node = (IdentifierStackElement)specific_stmt_node.branches[0];
NonterminalStackElement other_assign_node = (NonterminalStackElement)specific_stmt_node.branches[1];
//other_assign→= expr; | [simple_expr] = expr;
if (other_assign_node.branches.Count == 3)
{
NonterminalStackElement expr_node = (NonterminalStackElement)other_assign_node.branches[1];
Dictionary <string, Value> bindings = findBindings(binding_stack, identifier_node.content);
if (bindings != null)
{
string type = bindings[identifier_node.content].type;
if (type.Contains("func"))
{
throw new ExecutorException("不可给函数赋值", identifier_node.linenum);
}
else if (type.Contains("Array"))
{
throw new ExecutorException("不可给数组类型赋单个的值", identifier_node.linenum);
}
else
{
Value v = Evaluator.eval_expr(expr_node, binding_stack);
bindings[identifier_node.content] = adjustType(type, v);
}
}
else
{
throw new ExecutorException("未定义的标识符" + identifier_node.content, identifier_node.linenum);
}
}
//other_assign → [simple_expr] = expr;
else
{
NonterminalStackElement simple_expr_node = (NonterminalStackElement)other_assign_node.branches[1];
NonterminalStackElement expr_node = (NonterminalStackElement)other_assign_node.branches[4];
Dictionary <string, Value> bindings = findBindings(binding_stack, identifier_node.content);
if (bindings != null)
{
string type = bindings[identifier_node.content].type;
if (type.Contains("func"))
{
throw new ExecutorException("不可给函数赋值", specific_stmt_node.linenum);
}
else if (type.Contains("Array"))
{
Value v = Evaluator.eval_expr(expr_node, binding_stack);
type = type.Substring(0, type.Length - 5);
//检查赋值的类型和变量类型是否相符
v = adjustType(type, v);
int index = get_array_len_from_simple_expr(simple_expr_node, binding_stack);
bindings[identifier_node.content].changeValueOfArray(index, v.getString());
}
else
{
throw new ExecutorException("该变量并不是数组类型，无法赋值", identifier_node.linenum);
}
}
else
{
throw new ExecutorException("未定义的标识符" + identifier_node.content, identifier_node.linenum);
}
}
return(null);
}
//declare_stmt→type declaratee_lst;
else if (specific_stmt_node.name == "declare_stmt")
{
Executor.declareVaraible(specific_stmt_node, binding_stack);
return(null);
}
// compound_stmt→{stmt_lst}|{}
else if (specific_stmt_node.name == "compound_stmt")
{
if (specific_stmt_node.branches.Count == 2)
{
return(null);
}
//{stmt_lst}执行完就要出栈bindings
else
{
Dictionary <string, Value> new_local_bindings = new Dictionary <string, Value>();
binding_stack.Add(new_local_bindings);
//stmt_lst → stmt stmt_lst | stmt
NonterminalStackElement stmt_lst_node = (NonterminalStackElement)specific_stmt_node.branches[1];
Value v = executeStmtLst(stmt_lst_node, binding_stack);
//{stmt_lst}执行完就要出栈bindings
binding_stack.RemoveAt(binding_stack.Count - 1);
return(v);
}
}
// return_stmt→return expr; | return;
else if (specific_stmt_node.name == "return_stmt")
{
// return_stmt→ return;
if (specific_stmt_node.branches.Count == 2)
{
return(new NullValue(specific_stmt_node.linenum));
}
// return_stmt→return expr;
else
{
NonterminalStackElement expr_node = (NonterminalStackElement)specific_stmt_node.branches[1];
Value v = Evaluator.eval_expr(expr_node, binding_stack);
return(v);
}
}
//expr_stmt→expr;
else if (specific_stmt_node.name == "expr_stmt")
{
NonterminalStackElement expr_node = (NonterminalStackElement)specific_stmt_node.branches[0];
Value v = Evaluator.eval_expr(expr_node, binding_stack);
if (v == null)
{
return(null);
}
if (v.type == "func")
{
throw new ExecutorException("函数调用格式错误", specific_stmt_node.linenum);
}
else
{
return(null);
}
}
//while_if_stmt→if(expr)while_compound_stmt while_more_ifelse
else if (specific_stmt_node.name == "while_if_stmt")
{
NonterminalStackElement expr_node = (NonterminalStackElement)specific_stmt_node.branches[2];
Value expr_value = Evaluator.eval_expr(expr_node, binding_stack);
if (expr_value.getBoolean())
{
NonterminalStackElement compound_stmt = (NonterminalStackElement)specific_stmt_node.branches[4];
return(executeStmt(compound_stmt, binding_stack));
}
else
{
NonterminalStackElement more_if_else_node = (NonterminalStackElement)specific_stmt_node.branches[5];
//while_more_ifelse→ε|else while_else_stmt
if (more_if_else_node.branches.Count == 0)
{
return(null);
}
else
{
//while_else_stmt→while_if_stmt | while_compound_stmt
NonterminalStackElement else_stmt = (NonterminalStackElement)more_if_else_node.branches[1];
NonterminalStackElement specific_else_stmt = (NonterminalStackElement)else_stmt.branches[0];
return(executeStmt(specific_else_stmt, binding_stack));
}
}
}
//while_compound_stmt→{while_stmt_lst}|{}
else if (specific_stmt_node.name == "while_compound_stmt")
{
if (specific_stmt_node.branches.Count == 2)
{
return(null);
}
//{stmt_lst}执行完就要出栈bindings
else
{
Dictionary <string, Value> new_local_bindings = new Dictionary <string, Value>();
binding_stack.Add(new_local_bindings);
NonterminalStackElement stmt_lst_node = (NonterminalStackElement)specific_stmt_node.branches[1];
//while_stmt_lst →while_substmt while_stmt_lst | while_substmt
Value v = executeStmtLst(stmt_lst_node, binding_stack);
//{stmt_lst}执行完就要出栈bindings
binding_stack.RemoveAt(binding_stack.Count - 1);
return(v);
}
}
//break_stmt→break;
else if (specific_stmt_node.name == "break_stmt")
{
throw new ExecutorException("暂不实现");
}
//continue_stmt→continue;
else if (specific_stmt_node.name == "continue_stmt")
{
throw new ExecutorException("暂不实现");
}
else
{
throw new ExecutorException("Stmt/While_sub_stmt应该只有这些");
}
}
