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from .expressions import Expression, SubroutineCall
from .utils import *
class Statement:
def __init__(self):
pass
@classmethod
def from_tokens(cls, tokens: list) -> tuple:
for StatementClass in [LetStatement, DoStatement, ReturnStatement, IfStatement]:
stmt, dt = StatementClass.from_tokens(tokens)
if stmt is not None:
return (stmt, dt)
return (None, 0)
class StatementList:
def __init__(self, statements: list[Statement]):
self.statements = statements
@classmethod
def from_tokens(cls, tokens: list) -> tuple:
t = 0
statements = []
while True:
stmt, dt = Statement.from_tokens(tokens[t:])
if stmt is None:
break
statements.append(stmt)
t += dt
return (StatementList(statements), t)
def print_verbose(self):
for stmt in self.statements:
stmt.print_verbose()
class LetStatement:
def __init__(self, name, expr):
self.name = name
self.expr = expr
@classmethod
def from_tokens(cls, tokens: list) -> tuple:
"""Construct let statement.
Format:
'let' <name> '=' <expression> ';'
"""
if len(tokens) < 5 or tokens[0] != "let":
return (None, 0)
name = tokens[1]
if name.type != "identifier":
raise UnexpectedToken("variable name", name)
if tokens[2] != "=":
raise UnexpectedToken("=", tokens[2])
t = 3
expr, dt = Expression.from_tokens(tokens[t:])
if expr is None:
raise UnexpectedToken(f"Expected expression", tokens[3])
t += dt
if tokens[t] != ";":
raise UnexpectedToken(";", tokens[t])
return (LetStatement(name, expr), t + 1)
def print_verbose(self):
print(f"Let {self.name} be {self.expr}")
class DoStatement:
def __init__(self, subcall: SubroutineCall):
self.subcall = subcall
@classmethod
def from_tokens(cls, tokens: list) -> tuple:
"""Construct do statement.
Format:
'do' <subroutine call> ';'
"""
if len(tokens) < 5 or tokens[0] != "do":
return (None, 0)
t = 1
subcall, dt = SubroutineCall.from_tokens(tokens[1:])
if subcall is None:
raise UnexpectedToken("subroutine call", tokens[1])
t += dt
if tokens[t] != ";":
raise UnexpectedToken(";", tokens[t])
return (DoStatement(subcall), t + 1)
def print_verbose(self):
print(f"Do {self.subcall}")
class ReturnStatement:
def __init__(self, expr: Expression):
self.expr = expr
@classmethod
def from_tokens(cls, tokens: list) -> tuple:
"""Construct return statement.
Format:
'return' <expression>? ';'
"""
if len(tokens) < 3 or tokens[0] != "return":
return (None, 0)
t = 1
expr, dt = Expression.from_tokens(tokens[1:])
t += dt
if tokens[t] != ";":
raise UnexpectedToken(";", tokens[t])
return (ReturnStatement(expr), t + 1)
def print_verbose(self):
print(f"Return {self.expr or 'null'}")
class IfStatement:
def __init__(self, condition: Expression, then: StatementList, else_then=None):
self.condition = condition
self.then = then
self.else_then = else_then
@classmethod
def from_tokens(cls, tokens: list) -> tuple:
"""Construct if statement.
Format:
'if' '(' <expression> ')' '{' <statement list> '}' ('else' '{' <statement list '}')?
"""
if len(tokens) < 6 or tokens[0] != "if":
return (None, 0)
if tokens[1] != LEFT_PAREN:
raise UnexpectedToken(LEFT_PAREN, tokens[1])
t = 2
cond, dt = Expression.from_tokens(tokens[2:])
if cond is None:
raise JackSyntaxError(f"Expected condition", tokens[2])
t += dt
if tokens[t] != RIGHT_PAREN:
raise UnexpectedToken(RIGHT_PAREN, tokens[t])
if tokens[t + 1] != LEFT_BRACE:
raise UnexpectedToken(LEFT_BRACE, tokens[t + 1])
t += 2
then, dt = StatementList.from_tokens(tokens[t:])
t += dt
if tokens[t] != RIGHT_BRACE:
raise UnexpectedToken(RIGHT_BRACE, tokens[t])
t += 1
if tokens[t] != "else":
return (IfStatement(cond, then), t)
if tokens[t + 1] != LEFT_BRACE:
raise UnexpectedToken(LEFT_BRACE, tokens[t + 1])
t += 2
else_then, dt = StatementList.from_tokens(tokens[t:])
t += dt
if tokens[t] != RIGHT_BRACE:
raise UnexpectedToken(RIGHT_BRACE, tokens[t])
return (IfStatement(cond, then, else_then), t + 1)
def print_verbose(self):
print(f"If {self.condition} then:")
self.then.print_verbose()
if self.else_then is not None:
print("Else then:")
self.else_then.print_verbose()
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