private Expr doShift(Expr left, int level)
{
string op = lookahead.Text;
EatToken();
Expr right = factor();
Precedence next;
while ((next = nextOperator()) != null && rightIsExpr(level, next))
{
right = doShift(right, next.Level);
}
BinaryExpr exp = new BinaryExpr();
exp.Left = left;
exp.Right = right;
exp.Op = op;
return(exp);
}
private void GenStmt(Stmt stmt, Env table, ILGenerator il)
{
if (stmt is Sequence)
{
Sequence seq = (Sequence)stmt;
GenStmt(seq.First, table, il);
GenStmt(seq.Second, table, il);
}
else if (stmt is ImportStmt)
{
// 只能导入.Net模块
ImportStmt import = (ImportStmt)stmt;
Reflect.Assembly asm = null;
if (import.Name == "System")
{
// 首先在核心模块中查找
// 获取int类型所在的程序集(mscorlib.dll)
asm = Reflect.Assembly.GetAssembly(typeof(int));
}
else
{
string root = Framework.GetFrameworkDirectory();
string assembly = IO.Path.Combine(root, import.Name + ".dll");
asm = Reflect.Assembly.LoadFile(assembly); // TODO 错误处理
}
table.AddModule(new Module(import.Name, asm));
}
else if (stmt is DeclareVar)
{
DeclareVar declare = (DeclareVar)stmt;
Type type = declare.Type;
if (type == null)
{
type = TypeOfExpr(declare.Expr, table);
}
if (table.IsDeclared(declare.Name))
{
throw new Exception(String.Format("A local variable named '{0}' is already defined in this scope", declare.Name));
}
// TODO 保存本地变量的位置索引
table[declare.Name] = new LocalVariable(il.DeclareLocal(type));
// set the initial value
BinaryExpr be = new BinaryExpr();
Variable var = new Variable();
var.Name = declare.Name;
be.Left = var;
be.Op = "=";
if (declare.Expr is Undefined)
{
// FIXME 根据所声明变量的类型赋初值
IntLiteral expr = new IntLiteral();
expr.Value = 0;
be.Right = expr;
}
else
{
be.Right = declare.Expr;
}
GenExpr(be, table, il);
}
else if (stmt is Return)
{
Return ret = (Return)stmt;
GenExpr(ret.Expr, table, il);
}
else if (stmt is Function)
{
// 定义全局函数
DefineGlobalMethod((Function)stmt, table);
}
else if (stmt is Print)
{
Print print = (Print)stmt;
GenExpr(print.Expr, table, il);
Reflect.MethodInfo mi = typeof(Console).GetMethod("WriteLine", new Type[] { TypeOfExpr(print.Expr, table) });
il.Emit(OpCodes.Call, mi);
}
else if (stmt is IfStmt)
{
IfStmt ifStmt = (IfStmt)stmt;
// 代码块的结束位置
Label End = il.DefineLabel();
// 生成条件表达式
GenExpr(ifStmt.Cond, table, il);
il.Emit(OpCodes.Brfalse, End);
// then代码块
//il.BeginScope();
GenStmt(ifStmt.Then, table, il);
//il.EndScope();
il.MarkLabel(End);
}
else if (stmt is IfElseStmt)
{
IfElseStmt ifElseStmt = (IfElseStmt)stmt;
// 分支标签
Label ThenEnd = il.DefineLabel();
Label End = il.DefineLabel();
// 条件表达式
GenExpr(ifElseStmt.Cond, table, il);
il.Emit(OpCodes.Brfalse, ThenEnd);
// then分支
GenStmt(ifElseStmt.Then, table, il);
il.Emit(OpCodes.Br, End);
il.MarkLabel(ThenEnd);
// else分支
GenStmt(ifElseStmt.Else, table, il);
il.MarkLabel(End);
}
else if (stmt is WhileLoop)
{
WhileLoop whileLoop = (WhileLoop)stmt;
Label LoopStart = il.DefineLabel();
Label LoopEnd = il.DefineLabel();
il.MarkLabel(LoopStart);
GenExpr(whileLoop.Cond, table, il);
il.Emit(OpCodes.Brfalse, LoopEnd);
GenStmt(whileLoop.Body, table, il);
il.Emit(OpCodes.Br, LoopStart);
il.MarkLabel(LoopEnd);
}
//else if (stmt is ForLoop)
//{
// ForLoop forLoop = (ForLoop)stmt;
// Assign assign = new Assign();
// assign.Ident = forLoop.Name;
// assign.Expr = forLoop.From;
// GenStmt(assign, table, il);
// // jump to the test
// Label test = il.DefineLabel();
// il.Emit(OpCodes.Br, test);
// // statements in the body of the for loop
// Label body = il.DefineLabel();
// il.MarkLabel(body);
// GenStmt(forLoop.Body, table, il);
// // to (increment the value of x)
// il.Emit(OpCodes.Ldloc, table[forLoop.Name]);
// il.Emit(OpCodes.Ldc_I4, 1);
// il.Emit(OpCodes.Add);
// Store(forLoop.Name, table, il);
// // **test** does x equal 100? (do the test)
// il.MarkLabel(test);
// il.Emit(OpCodes.Ldloc, table[forLoop.Name]);
// GenExpr(forLoop.To, table, il);
// il.Emit(OpCodes.Blt, body);
//}
//else if (stmt is Expr)
//{
// GenExpr((Expr)stmt, table, il);
//}
else if (stmt is Simple)
{
Simple simple = (Simple)stmt;
GenExpr(simple.Expr, table, il);
// TODO 无括号的函数调用
}
else if (stmt is EmptyStmt)
{
// empty statement
// do nothing
}
else
{
throw new Exception("don't know how to gen a " + stmt.GetType().Name);
}
}
private void GenExpr(Expr expr, Env table, ILGenerator il)
{
if (expr is StrLiteral)
{
il.Emit(OpCodes.Ldstr, ((StrLiteral)expr).Value);
}
else if (expr is IntLiteral)
{
il.Emit(OpCodes.Ldc_I4, ((IntLiteral)expr).Value);
}
else if (expr is BoolLiteral)
{
il.Emit(OpCodes.Ldc_I4, ((BoolLiteral)expr).Value);
}
else if (expr is Variable)
{
string name = ((Variable)expr).Name;
Load(name, table, il);
}
else if (expr is PrimaryExpr)
{
PrimaryExpr pe = (PrimaryExpr)expr;
//GenExpr(pe.Lhs, table, il);
if (pe.Lhs is Variable) // LHS此时可能是命名空间、类型名、实例变量（包括函数名）等
{
string name = ((Variable)pe.Lhs).Name;
if (pe.Postfix is CallExpr)
{
// TODO 目前不考虑链式调用
CallExpr ce = (CallExpr)pe.Postfix;
// 函数调用
if (globalFunctions.ContainsKey(name))
{
// 载入参数
foreach (var arg in ce.Args)
{
GenExpr(arg, table, il);
}
// 调用函数
Reflect.MethodInfo mi = globalFunctions[name];
il.Emit(OpCodes.Call, mi);
}
else if (table.HasInstance(name))
{
throw new Exception(String.Format("'{0}'是变量，不是函数", name));
}
else
{
throw new Exception(String.Format("当前上下文中不存在名称'{0}'", name));
}
}
else if (pe.Postfix is MemberAccessExpr)
{
// 目前只实现了导入模块，还没有实现Class
MemberAccessExpr mae = (MemberAccessExpr)pe.Postfix;
if (mae.Postfix is MemberAccessExpr)
{
string ns = ns = name + "." + mae.Ident;;
// 合并命名空间(CLR的类型名在运行时是命名空间的一部分)
PrimaryExpr exp = new PrimaryExpr();
Variable var = new Variable();
var.Name = ns;
exp.Lhs = var;
exp.Postfix = mae.Postfix;
// 递归生成合并后的表达式
GenExpr(exp, table, il);
}
else if (mae.Postfix is CallExpr)
{
// 调用C#模块中的方法
CallExpr ce = (CallExpr)mae.Postfix;
// 在所有模块中间查找类型和方法
Type type = FirstMatchType(name, table);
if (type != null)
{
// 载入参数
List <Type> typelist = new List <Type>();
foreach (var arg in ce.Args)
{
typelist.Add(TypeOfExpr(arg, table));
GenExpr(arg, table, il);
}
// 调用函数
Reflect.MethodInfo mi = type.GetMethod(mae.Ident, typelist.ToArray());
if (mi != null)
{
il.Emit(OpCodes.Call, mi);
}
else
{
throw new Exception(String.Format("方法{0}未发现", mae.Ident));
}
}
else
{
throw new Exception(String.Format("类型{0}未发现", name));
}
}
else
{
//此时 Postfix == null
// 访问属性
// 例如 a.Length
throw new NotImplementedException();
}
}
}
else
{
// TODO OO语言中，可以考虑在字面量上访问方法
// 例如 10.to_s() => "10"
throw new NotImplementedException();
}
}
else if (expr is BinaryExpr)
{
BinaryExpr be = (BinaryExpr)expr;
// 赋值
if (be.Op.Equals("="))
{
GenExpr(be.Right, table, il);
if (be.Left is Variable)
{
Store(((Variable)be.Left).Name, table, il);
}
else
{
throw new Exception("except a lvalue at assign");
}
}
else
{
// 算术运算
// FIXME IL没有一些条件运算，需要单独提出来实现
GenExpr(be.Left, table, il);
GenExpr(be.Right, table, il);
switch (be.Op)
{
case "+":
il.Emit(OpCodes.Add);
break;
case "-":
il.Emit(OpCodes.Sub);
break;
case "*":
il.Emit(OpCodes.Mul);
break;
case "/":
il.Emit(OpCodes.Div);
break;
case "%":
il.Emit(OpCodes.Rem);
break;
case "<":
il.Emit(OpCodes.Clt);
break;
case ">":
il.Emit(OpCodes.Cgt);
break;
case "==":
il.Emit(OpCodes.Ceq);
break;
case "<=":
//il.Emit(OpCodes.Cgt); // FIXME
//break;
case ">=":
//il.Emit(OpCodes.Clt); // FIXME
//break;
case "!=":
//il.Emit(OpCodes.Ceq); // FIXME
//break;
default:
throw new Exception("Unrecognized operator: " + be.Op);
}
}
}
else if (expr is Undefined)
{
return;
}
else
{
throw new Exception("don't know how to generate " + expr.GetType().Name);
}
}