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from .tokens import Token
from .utils import *
SCOPES = ["static", "field", "var"]
PRIMITIVE_TYPES = ["int", "char", "boolean"]
class Class:
def __init__(self, name: Token, variables: list, subroutines: list):
self.name = name
self.variables = variables
self.subroutines = subroutines
@classmethod
def from_tokens(cls, tokens: list):
"""Construct a class from a list of tokens.
In standard Jack, one file is exactly one class.
Format:
class <name> {
<zero or more class variable declarations>
<zero or more subroutines>
}
"""
if len(tokens) < 4:
return None
if tokens[0] != "class":
raise JackSyntaxError(
f"Expected `class`, got `{tokens[0]}` instead", tokens[0]
)
name = tokens[1]
if name.type != "identifier":
raise JackSyntaxError(f"You cannot name a class `{name}`", name)
if tokens[2] != LEFT_BRACE:
raise JackSyntaxError(
f"Expected `{LEFT_BRACE}`, got `{tokens[2]}` instead", tokens[2]
)
tokens_consumed = 3
while True:
variables, token_cnt = Variable.from_tokens(
tokens[tokens_consumed:], context="class"
)
if variables is None:
break
variables.print_verbose()
tokens_consumed += token_cnt
return Class(name, variables, [])
class Variable:
def __init__(self, scope: Token, type: Token, names: list[Token]):
self.scope = scope
self.type = type
self.names = names
@classmethod
def from_tokens(cls, tokens: list, context: str) -> tuple:
"""Construct variable declaration statement from a list of tokens.
Return a tuple of an instance of Variable and number of tokens consumed.
When `tokens` does not begin with a variable declaration, return (None, 0).
context -- "class" (<scope> = static | field) or "subroutine" (<scope> = var)
Format:
<scope> <type> <one or more names, joined with a comma>;
<scope> = static | field | var
<type> = int | char | boolean | <class name>
"""
if len(tokens) < 4 or tokens[0] not in SCOPES:
# not variable declaration
return (None, 0)
scope = tokens[0]
if scope in ["static", "field"] and context != "class":
raise JackSyntaxError(
f"You cannot declare a {scope} variable in a subroutine", scope
)
if scope == "var" and context != "subroutine":
raise JackSyntaxError(
f"You cannot declare a local variable outside of a subroutine",
scope,
)
type = tokens[1]
if type not in PRIMITIVE_TYPES and type.type != "identifier":
raise JackSyntaxError(f"Expected datatype, got `{tokens[1]}` instead", type)
tokens_consumed = 2
names = [] # names of variables
expecting_identifier = True
for token in tokens[2:]:
tokens_consumed += 1
if token.type == "identifier":
if expecting_identifier:
names.append(token)
expecting_identifier = False
else:
raise JackSyntaxError(f"Expected `,`, got `{token}` instead", token)
elif token == ",":
if not expecting_identifier:
expecting_identifier = True
else:
raise JackSyntaxError(
f"Expected variable name, got `,` instead", token
)
elif token == ";":
if expecting_identifier:
raise JackSyntaxError(
f"Expected variable name, got `;` instead", token
)
break
else:
expected = "variable name" if expecting_identifier else "`,` or `;`"
raise JackSyntaxError(
f"Expected {expected}, got `{token}` instead", token
)
return (Variable(scope, type, names), tokens_consumed)
def print_verbose(self):
print(f"Declare {len(self.names)} variable(s):")
for name in self.names:
print(self.scope, self.type, name)
class Subroutine:
def __init__(self):
pass
class Statement:
def __init__(self):
super().__init__()
class IfStatement(Statement):
def __init__(self):
super().__init__()
|
