def eq_type(self, t1, t2):
"""
Helper function to check if two given type node is that of the
same type. Precondition is that both t1 and t2 are that of class Type
"""
t1_is_type = isinstance(t1, ast.Type) or isinstance(
t1, ast.Array_Type) or isinstance(t1, ast.Dict_Type)
t2_is_type = isinstance(t2, ast.Type) or isinstance(
t2, ast.Array_Type) or isinstance(t2, ast.Dict_Type)
if not (t1_is_type and t2_is_type):
raise ParseError(
f"eq_type invoked on non-type objects, {t1.__class__} and {t2.__class__}"
)
# {} <- type name dict
# {} <- ast.dict_type(None, None)
if isinstance(t1, ast.Type) and isinstance(t2, ast.Type):
return t1.name == t2.name
elif isinstance(t1, ast.Array_Type) and isinstance(t2, ast.Array_Type):
return self.eq_type(t1.innerType, t2.innerType)
elif isinstance(t1, ast.Dict_Type) and isinstance(t2, ast.Dict_Type):
t2_is_empty_dict = self.eq_type(
t2.key_type, ast.Type("NullType")) and self.eq_type(
t2.val_type, ast.Type("NullType"))
if t2_is_empty_dict:
return True
return self.eq_type(t1.key_type, t2.key_type) and self.eq_type(
t1.val_type, t2.val_type)
else:
return False
def check_ArrayBuiltinCall(self, node: ast.ArrayBuiltinCall,
st: SymbolTable):
"""
builtinFunction is one of .pop, .append, or .remove.
"""
# first, verify that variable is an array
array_type = st.lookup_variable(node.arrayID, node.coord)
if not isinstance(array_type, ast.Array_Type):
raise ParseError(
f"Tried to call {node.builtinFunction} on non array variable of type {array_type.name}",
node.coord,
)
# check if argumentExpression is of the right type.
inner_type = array_type.innerType
argument_expr_type = self.typecheck(node.argumentExpression)
if node.builtinFunction == ".pop":
if not self.eq_type(argument_expr_type, ast.Type("int")):
raise ParseError(
f"Tried to pop from array with non integer index of type {argument_expr_type.name}",
node.coord,
)
else:
return inner_type
else:
if not self.eq_type(argument_expr_type, inner_type):
raise ParseError(
f"Mismatch of types on call of {node.builtinFunction}, expected {inner_type.name}"
)
else:
return ast.Type("NullType")
def check_StmtList(self, node: ast.StmtList, st):
"""
Iterates through a StmtList, and determines the type of each statement.
Used for every scope be it if statements, while loops, etc...
"""
retTypeFound = False
retType = ast.Type("NullType")
for stmt in node.stmt_lst:
if retTypeFound:
raise ParseError(
f"Found extra statement(s) after function returned",
node.coord)
elif isinstance(stmt, ast.RetStmt) or isinstance(
stmt, ast.BreakStmt):
retTypeFound = True
retType = self.typecheck(stmt, st)
elif isinstance(stmt, ast.IfStmt):
ifStmtType = self.typecheck(stmt, st)
if not self.eq_type(ifStmtType, ast.Type("NullType")):
retTypeFound = True
retType = ifStmtType
else:
stmtType = self.typecheck(stmt, st)
return retType
def check_WhileStmt(self, node: ast.WhileStmt, st: SymbolTable):
cond_type = self.typecheck(node.cond, st)
if not self.eq_type(cond_type, ast.Type("bool")):
raise ParseError("Condition in While Statement not of type bool.",
node.coord)
st.push_while_scope()
self.typecheck(node.body, st)
st.pop_while_scope()
return ast.Type("NullType")
def check_ElifStmt(self, node: ast.ElifStmt, st: SymbolTable):
cond_type = self.typecheck(node.cond, st)
if not self.eq_type(cond_type, ast.Type("bool")):
raise ParseError("Condition in Elif not of type bool.", node.coord)
trueBodyType = self.typecheck(node.true_body, st)
if node.false_body is not None:
falseBodyType = self.typecheck(node.false_body, st)
if not node.false_body or self.eq_type(falseBodyType,
ast.Type("NullType")):
return ast.Type("NullType")
return trueBodyType
def check_DictBuiltinCall(self, node: ast.DictBuiltinCall,
st: SymbolTable):
# Check that ID is actually dict
# idType = st.lookup_variable(node.dictID, node.coord)
# if not self.eq_type(idType, ast.Type("dict")):
# raise ParseError(
# f"Tried to call {node.builtinFunction} on non dictionary variable of type {idType}",
# node.coord,
# )
key_type, val_type = st.lookup_dict(node.dictID, node.coord)
arg_type = self.typecheck(node.argumentExpression.exprs[0], st)
if not self.eq_type(key_type, arg_type):
raise ParseError(
f"Expected Key Type: {key_type}, but recieved Type {arg_type} for dict {node.dictID}",
node.coord,
)
if node.builtinFunction == ".get":
return val_type
elif node.builtinFunction == ".set":
if len(node.argumentExpression.exprs) != 2:
raise ParseError(
f"Builtin function 'set' requires 2 arguments.",
node.coord)
real_val_type = self.typecheck(node.argumentExpression.exprs[1],
st)
if not self.eq_type(val_type, real_val_type):
raise ParseError(
f"Expected Value Type: {val_type}, but recieved Type {real_val_type} for dict {node.dictID}",
node.coord,
)
return ast.Type("NullType")
def check_IfStmt(self, node: ast.IfStmt, st: SymbolTable):
cond_type = self.typecheck(node.cond, st)
if not self.eq_type(cond_type, ast.Type("bool")):
raise ParseError(
f"Condition of If statment was type {cond_type.name}, expected bool",
node.coord,
)
trueBodyType = self.typecheck(node.true_body, st)
if node.false_body is not None:
falseBodyType = self.typecheck(node.false_body, st)
if not node.false_body or self.eq_type(falseBodyType,
ast.Type("NullType")):
return ast.Type("NullType")
return trueBodyType
def p_primitive_type(self, p):
"""
primitive_type : INT
| STRING
| BOOLEAN
| NULLTYPE
"""
p[0] = ast.Type(p[1], p.lineno(1))
def check_UnaryOp(self, node: ast.UnaryOp, st):
"""
| "not" expression
| "-"expression # only for integer types
"""
expression_type = self.typecheck(node.expr, st)
if node.op == "not":
if not self.eq_type(expression_type, ast.Type("bool")):
raise ParseError(
f"Tried calling 'not' with non boolean variable of type {expression_type.name}"
)
else:
if not self.eq_type(expression_type, ast.Type("int")):
raise ParseError(
f"Tried calling '-' with non integer variable of type {expression_type.name}"
)
return expression_type
def check_VarAssign(self, node: ast.VarAssign, st: SymbolTable):
"""
variableName "=" expression # variableName must already be declared
"""
declaredType = st.lookup_variable(node.name, node.coord)
expressionType = self.typecheck(node.expr, st)
if not self.eq_type(declaredType, expressionType):
raise ParseError(
f"Variable {node.name} was declared as type {declaredType.name} but was assigned value of {expressionType.name} type",
node.coord,
)
return ast.Type("NullType")
def check_BinOp(self, node: ast.BinOp, st):
"""
NOTE
You should also check if the type of the left and right operation
makes sense in the context of the operator (ie., you should not be
able to add/subtract/multiply/divide strings or booleans). In this
example, it only checks if the left and right expressions are of the
same type, but that won't be sufficient for your project.
| expression "+" expression # integer or array types only
| expression "-" expression # integer type only
| expression "*" expression # integer type only
| expression "/" expression # integer type only
| expression "and" expression # boolean types only
| expression "or" expression # boolean types only
| expression "==" expression
| expression "!=" expression
| expression "%" expression # integer type only
| expression "<" expression # integer type only
| expression ">" expression # integer type only
| expression "<=" expression # integer type only
| expression ">=" expression # integer type only
"""
left_type = self.typecheck(node.left, st)
right_type = self.typecheck(node.right, st)
if node.op in {"+", "-", "*", "/", "%", "<", ">", "<=", ">="}:
if (not self.eq_type(left_type, ast.Type("int"))) or (
not self.eq_type(right_type, ast.Type("int"))):
raise ParseError(
f"Tried to call integer binary operation on {left_type.name} and {right_type.name} types",
node.coord,
)
return (ast.Type("bool")
if node.op in {"<", ">", "<=", ">="} else ast.Type("int"))
if node.op in {"and", "or"}:
if (not self.eq_type(left_type, ast.Type("bool"))) or (
not self.eq_type(right_type, ast.Type("bool"))):
raise ParseError(
f"Tried to call boolean binary operation on {left_type.name} and {right_type.name} types",
node.coord,
)
return ast.Type("bool")
return ast.Type("bool")
def check_ArraySlice(self, node: ast.ArraySlice, st: SymbolTable):
"""
| arrayName"["expression ":" expression "]" # expressions must be of type integer
"""
# first check that arrayName is a valid array ID
array_type = st.lookup_variable(node.name, node.coord)
if not isinstance(array_type, ast.Array_Type):
raise ParseError(
f"Tried to slice non array variable of type {array_type.name}",
node.coord,
)
# then check that expression is of type int
expr1_type = self.typecheck(node.expr1)
expr2_type = self.typecheck(node.expr2)
if not self.eq_type(expr1_type, ast.Type("int")) or not self.eq_type(
expr2_type, ast.Type("int")):
raise ParseError(
f"Tried to slice array with non integer indices of types {expr1_type.name}, {expr2_type.name}",
node.coord,
)
# return type of the array
return array_type
def check_VarDecl(self, node: ast.VarDecl, st):
"""
Checks if the expr declared with the variable has the same type that the
variable was declared with.
"""
declared_type = node.type
expression_type = self.typecheck(node.expr, st)
# If array Type expression Type can be [None]
if not self.eq_type(declared_type, expression_type):
raise ParseError(
f"Tried to declare variable of type {declared_type.name} but with value of type {expression_type.name}",
node.coord,
)
if isinstance(declared_type, ast.Dict_Type):
st.declare_dict(node.name, node.type.key_type, node.type.val_type,
node.coord)
st.declare_variable(node.name, node.type, node.coord)
return ast.Type("NullType")
def check_ArrayIndex(self, node: ast.ArrayIndex, st: SymbolTable):
"""
| arrayName"["expression"]" # expression must be of type integer
"""
# first check that arrayName is a valid array ID
array_type = st.lookup_variable(node.name, node.coord)
if not isinstance(array_type, ast.Array_Type):
raise ParseError(
f"Tried to index non array variable of type {array_type.name}",
node.coord,
)
# then check that expression is of type int
expr_type = self.typecheck(node.expr, st)
if not self.eq_type(expr_type, ast.Type("int")):
raise ParseError(
f"Tried to index an array with non integer index of type {expr_type.name}",
node.coord,
)
# return inner typer of the array
return array_type.innerType
def check_FunctionDefn(self, node: ast.FunctionDefn, st: SymbolTable):
"""
"def" functionName "(" parameters ")" "->" type ":" functionBlock
"""
# add each param to the symboltable
# use symbol table to type check functionblock based on return type of function
# if type check passes, then remove params from symbol table
# save functional type in symbol table
st.push_scope()
st.push_return_scope(node.ret_type)
# pushes expected return type to symbol table
# Go through the parameters
param_types = []
if node.params.params:
for param in node.params.params:
if isinstance(param.type, ast.Dict_Type):
st.declare_dict(param.name, param.type.key_type,
param.type.val_type, param.coord)
st.declare_variable(param.name, param.type, param.coord)
param_types.append(param.type)
body_return_type = self.typecheck(node.body, st)
st.pop_return_scope()
st.pop_scope()
if not self.eq_type(node.ret_type, body_return_type):
raise ParseError(
f"Return type of function body {body_return_type.name} doesn't match declared return type of function {node.ret_type.name}",
node.coord,
)
st.declare_function(node.name, param_types, node.ret_type, node.coord)
return ast.Type("NullType")
def p_empty_dict(self, p):
"""
empty_dict : EMPTYDICT
"""
p[0] = ast.Constant(ast.Dict_Type(ast.Type("NullType"), ast.Type("NullType")), p[1], p.lineno(1))
def p_literal_string(self, p):
"""
literal : STRINGLITERAL
"""
p[0] = ast.Constant(ast.Type("str"), p[1], p.lineno(1))
def check_BreakStmt(self, node: ast.BreakStmt, st: SymbolTable):
if not st.is_in_while_scope():
raise ParseError("Attempted to break from outside while loop",
node.coord)
return ast.Type("NullType")
def p_literal_boolean(self, p):
"""
literal : TRUE
| FALSE
"""
p[0] = ast.Constant(ast.Type("bool"), p[1], p.lineno(1))
def p_literal_number(self, p):
"""
literal : NUMBER
"""
p[0] = ast.Constant(ast.Type("int"), p[1], p.lineno(1))
