// 可能不需要？编译时就确定？
private void BuildGlobalVarsInitFunction()
{
var globalVars = m_Tree.Root.OfType <VariableDeclarationStmt>();
var body = new BlockStmt()
{
Statements = new List <Statement>()
};
var func = new FunctionStmt()
{
Declaration = new FunctionDeclarationStmt
{
Name = "$init",
Signature = new FunctionSignature
{
Arguments = new List <Argument>(),
Return = "void"
}
},
Body = body
};
foreach (var g in globalVars)
{
body.Statements.Add(new ExpressionStmt
{
Expression = new Op2Expr
{
Operator = Op2Expr.Type.Assign,
Left = new VariableValueExpr {
Name = g.Name
},
Right = g.Assignment
}
});
g.Assignment = null;
}
m_Tree.Root.Add(func);
}
private void VisitStmt(Statement stmt, bool root = false)
{
if (stmt == null)
{
return;
}
m_StmtStack.Push(stmt);
Assert(!root || m_CanBeRoot.Contains(stmt.GetType()), $"Only function and variable declaration can be a root statement.");
Assert(root || !m_MustBeRoot.Contains(stmt.GetType()), $"Function defination must be a root statement.");
switch (stmt)
{
case FunctionDeclarationStmt fd:
{
VisitFunctionDeclaration(fd, false);
break;
}
case FunctionStmt f:
{
Assert(root, "Functions can only be the root statements.");
f.Symbol = VisitFunctionDeclaration(f.Declaration, true);
f.ScopeSymbols = f.Body.ScopeSymbols = new SymbolTable(); // function body has the same scope with arguments
foreach (var arg in f.Declaration.Signature.Arguments)
{
if (string.IsNullOrEmpty(arg.Name))
{
continue;
}
var argSym = new VariableSymbol {
Name = arg.Name, Type = arg.Type
};
Assert(f.ScopeSymbols.TryAdd(argSym),
$"Argument name '{arg.Name}' duplicated.");
arg.Symbol = argSym;
}
VisitStmt(f.Body);
break;
}
case BlockStmt block:
{
block.ScopeSymbols = block.ScopeSymbols ?? new SymbolTable(); // initialize a symbol table if not explicitly specified
foreach (var childStmt in block.Statements)
{
VisitStmt(childStmt);
}
break;
}
case VariableDeclarationStmt vd:
{
LinkTypeSymbol(vd.Type);
Assert(vd.Type != "void", $"'void' can't be used as a type.");
var sym = new VariableSymbol {
Name = vd.Name, Type = vd.Type, IsGlobal = root
};
Assert(GetNearestSymbolTable().TryAdd(sym),
$"Variable name '{vd.Name}' duplicated with another symbol under the same scope.");
vd.Symbol = sym;
VisitExpr(vd.Assignment);
if (vd.Assignment != null)
{
vd.Assignment = EliminateImplicitConv(vd.Assignment, vd.Type.Symbol);
}
break;
}
case IfStmt i:
{
VisitExpr(i.Condition);
i.Condition = EliminateImplicitConv(i.Condition, FindSymbol(CPrimitiveType.Int));
i.True.ScopeSymbols = new SymbolTable();
VisitStmt(i.True);
if (i.False != null)
{
i.False.ScopeSymbols = new SymbolTable();
}
VisitStmt(i.False);
break;
}
case ReturnStmt ret:
{
VisitExpr(ret.Value);
FunctionStmt func = null;
foreach (var ss in m_StmtStack.Reverse())
{
if (ss is FunctionStmt)
{
func = (FunctionStmt)ss;
break;
}
}
Assert(func.Declaration.Signature.Return != "void" || ret.Value == null, "This function does not return a value.");
Assert(ret.Value != null, "This function needs to return a value.");
ret.Value = EliminateImplicitConv(ret.Value, func.Declaration.Signature.Return.Symbol);
break;
}
case WhileStmt wh:
{
VisitExpr(wh.Condition);
wh.Condition = EliminateImplicitConv(wh.Condition, FindSymbol(CPrimitiveType.Int));
wh.Body.ScopeSymbols = new SymbolTable();
VisitStmt(wh.Body);
break;
}
case BreakStmt brk:
{
foreach (var st in m_StmtStack)
{
if (st is WhileStmt)
{
brk.Host = st;
break;
}
}
if (brk.Host == null)
{
SemanticsError("A 'break' statement may only be used within a 'while' statement.");
}
break;
}
case ExpressionStmt exprStmt:
{
switch (exprStmt.Expression)
{
case Op2Expr op2 when op2.Operator == Op2Expr.Type.Assign:
case FunctionCallExpr funcCall:
break;
default:
SemanticsError("Only assignment and function call expression can be a statement.");
break;
}
VisitExpr(exprStmt.Expression);
break;
}
default:
{
throw new ArgumentException("Unrecognizable statement type.");
}
}
m_StmtStack.Pop();
}