class ASTWalker(NodeVisitor):
def visit_Assignment(self, n):
if self.st.get_function(n.var):
raise SemanticError("function '%s' is not assignable" % n.var)
left = self.st.get_identifier(n.var)
if left is None:
raise SemanticError("use of undeclared identifier '%s'" % n.var)
right = self.visit(n.expr)
if left.type != right.type:
raise SemanticError("assigning to '%s' from incompatible type '%s'" % (left.type, right.type))
srcId = None
if isinstance(n.expr, (Assignment, Identifier, Constant)):
self.st.update_variable(n.var, left.type, right.value)
srcId = right.name
outasm = []
add(outasm, right.asm)
add(outasm, asm.AssignToVariable(n.var, srcId, self.st))
return Info(name=n.var, type=left.type, value=right.value, asm=outasm)
def visit_BinaryOp(self, n):
left = self.visit(n.lexpr)
right = self.visit(n.rexpr)
id1 = left.name if isinstance(n.lexpr, (Assignment, Identifier, Constant)) else None
id2 = right.name if isinstance(n.rexpr, (Assignment, Identifier, Constant)) else None
operators = {
"+": asm.Plus,
"-": asm.Minus,
"*": asm.Times,
"/": asm.Divide,
"%": asm.Modulo,
"!": asm.Not,
"&&": asm.And,
"||": asm.Or,
"<": asm.Lesser,
">": asm.Greater,
"<=": asm.LesserOrEqual,
">=": asm.GreaterOrEqual,
"==": asm.Equal,
"!=": asm.NotEqual,
}
if left.type in [T.Integer, T.Character, T.String] and right.type in [T.Integer, T.Character, T.String] and left.type != right.type:
raise SemanticError("invalid types of operands to binary expression '%s' ('%s' and '%s')" % (n.op, left.type, right.type))
outasm = []
add(outasm, left.asm)
add(outasm, right.asm)
add(outasm, operators[n.op](id1, id2, self.st))
return Info(type=T.Integer, asm=outasm)
def visit_Break(self, n):
if not self.st.in_loop():
raise SemanticError("'break' statement not in loop statement")
return Info(asm=asm.Break())
def visit_Cast(self, n, internal=False):
cast = self.visit(n.type)
expr = self.visit(n.expr)
id = expr.name if isinstance(n.expr, (Assignment, Identifier, Constant)) else None
if expr.type in [T.Character] and cast.type in [T.Integer, T.Character, T.String]:
pass
elif expr.type in [T.Integer] and cast.type in [T.Integer, T.Character]:
pass
elif expr.type in [T.String] and cast.type in [T.String]:
pass
elif internal and expr.type in [T.String] and cast.type in [T.Integer]:
pass
else:
raise SemanticError("cast from '%s' to '%s' is not allowed" % (expr.type, cast.type))
outasm = []
add(outasm, expr.asm)
add(outasm, asm.Cast(id, cast.type, self.st))
return Info(type=cast.type, value=expr.value, asm=outasm)
def visit_Compound(self, n):
output = []
type = None
for ch in n:
ch_visited = self.visit(ch)
add(output, ch_visited.asm)
if isinstance(ch, Return):
type = ch_visited.type
return Info(type=type, asm=asm.Compound(output))
def visit_Constant(self, n):
def is_int32(value):
return int(value) >= INT.minint and int(value) <= INT.maxint
type = self.visit(n.type)
if type.type in [T.Integer] and not is_int32(n.value):
raise SemanticError("integer constant '%s' is too large for its type" % n.value)
name = self.st.insert_to_global(n.value, type.type)
return Info(name=name, type=type.type, value=n.value)
def visit_Continue(self, n):
if not self.st.in_loop():
raise SemanticError("'continue' statement not in loop statement")
return Info(asm=asm.Continue())
def visit_Empty(self, n):
return Info(asm=asm.Empty())
def visit_For(self, n):
scope = self.st.insert_nonfunction_scope()
self.st.enter_scope(scope)
self.st.enter_loop()
start = self.visit(UnaryOp('+', n.start)) if isinstance(n.start, (Constant, Identifier)) else self.visit(n.start)
test = self.visit_Cast(Cast(Type('int'), n.test), True) if isinstance(n.test, (Assignment, Constant, Identifier)) else self.visit(n.test)
if test.type not in [T.Integer, T.Character, T.String]:
raise SemanticError("statement requires expression of scalar type ('%s' invalid)" % test.type)
next = self.visit(UnaryOp('+', n.next)) if isinstance(n.next, (Constant, Identifier)) else self.visit(n.next)
body = self.visit(n.body)
self.st.leave_loop()
self.st.leave_scope()
start_asm = []
add(start_asm, start.asm)
test_asm = []
add(test_asm, test.asm)
next_asm = []
add(next_asm, next.asm)
return Info(asm=asm.For(start_asm, test_asm, next_asm, body.asm, self.st))
def visit_FunctionCall(self, n):
def fce_param_types(fce_scope):
types = []
for param in sorted(fce_scope):
if param.startswith("#arg#"):
types.append(fce_scope[param].type)
return types
def arg_param_types(args):
types = []
for param in args:
types.append(param.type)
return types
if self.st.get_identifier(n.name):
raise SemanticError("called variable '%s' is not a function" % n.name)
fce = self.st.get_function(n.name)
if fce is None:
raise SemanticError("implicit declaration of function '%s' is invalid in VYPe13" % n.name)
fce_types = fce_param_types(fce.scope)
arg_list = [(arg, self.visit(arg)) for arg in n.args]
arg_types = arg_param_types([arg[1] for arg in arg_list])
if n.name == "print":
if len(n.args) == 0:
raise SemanticError("calling function '%s' with incompatible parameter types" % (n.name))
else:
if fce_types != arg_types:
if fce_types == ['void'] and arg_types == [None]:
pass
else:
raise SemanticError("calling function '%s' with incompatible parameter types" % (n.name))
call_list = []
call_name = []
for arg in arg_list:
add(call_list, arg[1].asm)
if isinstance(arg[0], (Assignment, Identifier, Constant)):
call_name.append(arg[1].name)
else:
call_name.append(None)
add(call_list, asm.Call(n.name, call_name, self.st))
return Info(name=n.name, type=fce.type, asm=call_list)
def visit_FunctionDefinition(self, n):
def fce_param_types(fce_scope):
types = []
for param in sorted(fce_scope):
if param.startswith("#arg#"):
types.append(fce_scope[param].type)
return types
def def_param_types(param_list):
types = []
for param in param_list:
types.append(self.visit(param.type).type)
return types
def def_param_names(param_list):
names = []
for param in param_list:
if param.name is not None:
names.append(param.name)
return names
if self.st.get_identifier(n.name):
raise SemanticError("redefinition of variable '%s' as a function" % n.name)
fce = self.st.get_function(n.name)
type = self.visit(n.type)
if n.name == "main" and type.type != T.Integer:
raise SemanticError("return type of '%s' is not '%s' but '%s'" % (n.name, T.Integer, type.type))
param_names = def_param_names(n.args)
if fce is None:
self.st.insert_function(n.name, type.type)
self.st.enter_scope(n.name)
for arg, i in zip(n.args, range(len(n.args))):
self.visit_FunctionParam(arg, i)
param_names = asm.GetParams(param_names, self.st)
self.st.set_function_def(n.name, False)
if n.code is not None:
code = self.visit(n.code)
self.st.set_function_def(n.name, True)
self.st.leave_scope()
else:
if fce.scope is None:
raise SemanticError("redefinition of '%s' as different kind of symbol" % (n.name))
self.st.enter_scope(n.name)
fce_types = fce_param_types(fce.scope)
def_types = def_param_types(n.args)
if fce_types != def_types or fce.type != type.type:
raise SemanticError("conflicting types for function '%s'" % (n.name))
if n.code is None:
raise SemanticError("redeclaration of function '%s'" % (n.name))
elif fce.defined is False and n.code is not None:
for arg, i in zip(n.args, range(len(n.args))):
self.visit_FunctionParam(arg, i)
param_names = asm.GetParams(param_names, self.st)
code = self.visit(n.code)
self.st.set_function_def(n.name, True)
elif fce.defined is True and n.code is not None:
raise SemanticError("redefinition of function '%s'" % (n.name))
self.st.leave_scope()
if n.code is not None and code.type != type.type:
if code.type is not None:
raise SemanticError("returning '%s' from function '%s' with result type '%s'" % (code.type, n.name, type.type))
if n.code is not None:
return Info(name=n.name, type=type.type, asm=asm.FunctionDefinition(n.name, param_names, code.asm, self.st))
else:
return Info(name=n.name, type=type.type, asm=asm.Empty())
def visit_FunctionParam(self, n, pos = None):
type = self.visit(n.type)
self.st.insert_arg_type(type.type, pos)
if n.name is not None:
self.st.insert_variable(n.name, type.type, position = pos)
return Info(name=n.name, type=type.type)
def visit_Identifier(self, n):
id = self.st.get_identifier(n.name)
if id is None:
raise SemanticError("use of undeclared identifier '%s'" % n.name)
return Info(name=n.name, type=id.type, value=id.value)
def visit_If(self, n):
test = self.visit_Cast(Cast(Type('int'), n.test), True) if isinstance(n.test, (Assignment, Constant, Identifier)) else self.visit(n.test)
if test.type not in [T.Integer, T.Character, T.String]:
raise SemanticError("statement requires expression of scalar type ('%s' invalid)" % test.type)
scope = self.st.insert_nonfunction_scope()
self.st.enter_scope(scope)
true = self.visit(n.true)
self.st.leave_scope()
scope = self.st.insert_nonfunction_scope()
self.st.enter_scope(scope)
false = self.visit(n.false)
self.st.leave_scope()
test_asm = []
add(test_asm, test.asm)
if isinstance(n.false, Empty):
return Info(asm=asm.IfOnly(test_asm, true.asm, self.st))
else:
return Info(asm=asm.IfElse(test_asm, true.asm, false.asm, self.st))
def visit_Program(self, n):
self.st = SymbolTable()
outasm = [self.visit(ch).asm for ch in n]
if self.st.get_function('main') is None:
raise SemanticError("undefined reference to 'main'")
return Info(asm=asm.Program(outasm, self.st.get_globals(finalize=True)))
def visit_Return(self, n):
if n.expr is not None:
expr = self.visit(n.expr)
id = expr.name if isinstance(n.expr, (Assignment, Identifier, Constant)) else None
outasm = []
add(outasm, expr.asm)
add(outasm, asm.Return(id, self.st))
return Info(type=expr.type, value=expr.value, asm=outasm)
else:
return Info(type=T.Void, asm=asm.ReturnEmpty())
def visit_Type(self, n):
if n == Type("int"):
type = T.Integer
elif n == Type("char"):
type = T.Character
elif n == Type("string"):
type = T.String
elif n == Type("void"):
type = T.Void
else:
type = T.Nothing
return Info(type=type)
def visit_UnaryOp(self, n):
expr = self.visit(n.expr)
id = expr.name if isinstance(n.expr, (Assignment, Identifier, Constant)) else None
outasm = []
add(outasm, expr.asm)
if n.op == '-':
add(outasm, asm.UnaryMinus(id, self.st))
elif n.op == '!':
add(outasm, asm.Not(id, self.st))
elif n.op == '+':
add(outasm, asm.UnaryPlus(id, self.st))
return Info(type=expr.type, asm=outasm)
def visit_VariableDeclaration(self, n):
type = self.visit(n.type)
vars = []
for i in n.vardecls:
vars.append(self.visit_VariableInitialize(i, type.type))
vars_asm = []
for var in vars:
add(vars_asm, var.asm)
return Info(type=type.type, asm=vars_asm)
def visit_VariableInitialize(self, n, type):
if self.st.get_function(n.name) or self.st.insert_variable(n.name, type) is False:
raise SemanticError("redefinition of function '%s' as a variable" % (n.name))
value = None
opasm = []
add(opasm, asm.DeclareVariable(n.name, self.st))
expr = self.visit(n.value)
add(opasm, expr.asm)
if n.value is not None:
if expr.type != type:
raise SemanticError("initializing '%s' with an expression of incompatible type '%s'" % (type, expr.type))
if isinstance(n.value, (Identifier, Constant)):
self.st.update_variable(n.name, type, expr.value)
value = expr.value
if isinstance(n.value, Constant):
add(opasm, asm.InitialiseVariable(n.name, expr.name, self.st))
elif isinstance(n.value, Identifier):
add(opasm, asm.InitialiseVariable(n.name, expr.name, self.st))
add(opasm, asm.AssignToVariable(n.name, expr.name, self.st))
else:
add(opasm, asm.AssignToVariable(n.name, None, self.st))
else:
add(opasm, asm.InitialiseVariable(n.name, None, self.st))
return Info(name=n.name, type=type, value=value, asm=opasm)
def visit_While(self, n):
scope = self.st.insert_nonfunction_scope()
self.st.enter_scope(scope)
self.st.enter_loop()
test = self.visit_Cast(Cast(Type('int'), n.test), True) if isinstance(n.test, (Assignment, Constant, Identifier)) else self.visit(n.test)
body = self.visit(n.body)
self.st.leave_loop()
self.st.leave_scope()
if test.type not in [T.Integer, T.Character, T.String]:
raise SemanticError("statement requires expression of scalar type ('%s' invalid)" % test.type)
test_asm = []
add(test_asm, test.asm)
return Info(asm=asm.While(test_asm, body.asm, self.st))
def visit_Program(self, n):
self.st = SymbolTable()
outasm = [self.visit(ch).asm for ch in n]
if self.st.get_function('main') is None:
raise SemanticError("undefined reference to 'main'")
return Info(asm=asm.Program(outasm, self.st.get_globals(finalize=True)))
