path: root/projects/hackc/classes.py

from .statements import StatementList
from .tokens import Token
from .utils import *

SCOPES = ["static", "field", "var"]
VAR_TYPES = ["int", "char", "boolean"]
RETURN_TYPES = ["int", "char", "boolean", "void"]
SUBROUTINE_CATS = ["constructor", "method", "function"]


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> '{'
            <variable>*
            <subroutine>*
        '}'
        """
        tokens_total = len(tokens)
        if tokens_total < 4:
            return None
        if tokens[0] != "class":
            raise UnexpectedToken("class", 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 UnexpectedToken(LEFT_BRACE, tokens[2])

        t = 3
        variables = []
        while t < tokens_total:
            variable, dt = Variable.from_tokens(tokens[t:], context="class")
            if variable is None:
                break
            variables.append(variable)
            t += dt

        subroutines = []
        while t < tokens_total:
            subroutine, dt = Subroutine.from_tokens(tokens[t:])
            if subroutine is None:
                break
            subroutines.append(subroutine)
            t += dt

        end = tokens[t]
        if end != RIGHT_BRACE:
            raise JackSyntaxError(
                f"Neither variable declaration nor subroutine: {end}", end
            )

        return Class(name, variables, subroutines)

    def print_verbose(self):
        print(f"Define class {self.name}")
        for variable in self.variables:
            variable.print_verbose()
        for subroutine in self.subroutines:
            subroutine.print_verbose()
        print(f"End of class {self.name}")


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> <name> (, <name>)* ;

        <scope> = static | field | var
        <type> = int | char | boolean | <class>
        """
        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 VAR_TYPES and type.type != "identifier":
            raise UnexpectedToken("datatype", type)

        t = 2
        names = []  # names of variables
        expecting_identifier = True
        found_semicolon = False

        for token in tokens[2:]:
            t += 1
            if token.type == "identifier":
                if expecting_identifier:
                    names.append(token)
                    expecting_identifier = False
                else:
                    raise UnexpectedToken(",", token)
            elif token == ",":
                if not expecting_identifier:
                    expecting_identifier = True
                else:
                    raise UnexpectedToken("variable name", token)
            elif token == ";":
                if expecting_identifier:
                    raise UnexpectedToken("variable name", token)
                found_semicolon = True
                break
            else:
                expected = "variable name" if expecting_identifier else "`,` or `;`"
                raise UnexpectedToken(expected, token)

        if not found_semicolon:
            # TODO: print caret at end of token
            raise JackSyntaxError(f"Missing semicolon", token)

        return (Variable(scope, type, names), t)

    def print_verbose(self):
        print(f"Declare {len(self.names)} variable(s):")
        for name in self.names:
            print(self.scope, self.type, name)


class ParamList:
    def __init__(self, params: list[tuple]):
        self.params = params

    @classmethod
    def from_tokens(cls, tokens: list) -> tuple:
        """Construct parameter list of subroutine from tokens.

        Format:
        (<type> <name> (, <type> <name>)*)?

        <type> = int | char | boolean | <class>
        """
        if not tokens:
            return (None, 0)

        if tokens[0] == RIGHT_PAREN:
            # empty param list, i.e. '(' ')'
            return (ParamList([]), 0)

        t = 0
        params = []
        for type, name, delim in zip(tokens[0::3], tokens[1::3], tokens[2::3]):
            if type not in VAR_TYPES and type.type != "identifier":
                raise UnexpectedToken("datatype", type)
            if not name:
                # TODO: print caret at end of type
                raise JackSyntaxError("Expected variable name", type)
            if name.type != "identifier":
                raise UnexpectedToken("variable name", name)
            if not delim:
                raise UnexpectedToken(f"`,` or `{RIGHT_PAREN}`", name)
            if delim == ",":
                t += 3
                params.append((type, name))
                continue
            elif delim == RIGHT_PAREN:
                t += 2
                params.append((type, name))
                break
            else:
                raise UnexpectedToken(f"`,` or `{RIGHT_PAREN}`", delim)

        return (ParamList(params), t)

    def print_verbose(self):
        print(f"Subroutine takes {len(self.params)} parameter(s):")
        for param in self.params:
            print(param[0], param[1])


class Subroutine:
    def __init__(
        self,
        category: Token,
        type: Token,
        name: Token,
        params: ParamList,
        variables: list,
        statements: StatementList,
    ):
        self.category = category
        self.type = type
        self.name = name
        self.params = params
        self.variables = variables
        self.statements = statements

    @classmethod
    def from_tokens(cls, tokens: list) -> tuple:
        """Construct subroutine from tokens.

        Format:
        <category> <return type> <name> '(' <paramlist> ')' '{' <variable>* <statement>* '}'

        <category> = constructor | method | function
        <return type> = int | char | boolean | void | <class>
        """
        if len(tokens) < 7 or tokens[0] not in SUBROUTINE_CATS:
            # not a subroutine
            return (None, 0)
        category = tokens[0]

        return_type = tokens[1]
        if return_type not in RETURN_TYPES and return_type.type != "identifier":
            raise UnexpectedToken("datatype", return_type)

        name = tokens[2]
        if name.type != "identifier":
            raise UnexpectedToken(f"{category} name", name)

        if tokens[3] != LEFT_PAREN:
            raise UnexpectedToken(LEFT_PAREN, tokens[3])

        t = 4
        params, dt = ParamList.from_tokens(tokens[t:])
        if params is None:
            raise JackSyntaxError("Expected parameter list", tokens[t])
        # it can be safely assumed that the next token is ')'
        t += dt + 1

        # TODO: catch IndexError
        body_open = tokens[t]
        if body_open != LEFT_BRACE:
            raise UnexpectedToken(LEFT_BRACE, body_open)
        t += 1

        variables = []
        while t < len(tokens):
            variable, dt = Variable.from_tokens(tokens[t:], context="subroutine")
            if variable is None:
                break
            variables.append(variable)
            t += dt

        statements, dt = StatementList.from_tokens(tokens[t:])
        t += dt

        body_close = tokens[t]
        if body_close != RIGHT_BRACE:
            raise UnexpectedToken(RIGHT_BRACE, body_close)
        t += 1

        return (
            Subroutine(category, return_type, name, params, variables, statements),
            t,
        )

    def print_verbose(self):
        print(f"Define {self.category} {self.type} {self.name}")
        self.params.print_verbose()
        for variable in self.variables:
            variable.print_verbose()
        self.statements.print_verbose()
        print(f"End of {self.category} {self.name}")