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from typing import NoReturn, Optional, cast
from tabla import Token, LexToken
from parse.base import BaseParser
from parse.ident import ParseIdent
from errors import Error
from astree.expr import Expr, BinarithmOp, ConstantExpr, NumberConstant, CallExpr, PrintExpr, BinarithmExpr, CompoundExpr, ReadExpr, AccessExpr, AssignExpr
class ParseExpr:
def __init__(self, parser: BaseParser):
self.parser = parser
def expr(self) -> (Expr | Error):
obj = self.binarithm(None, 0)
# =
tok = self.parser._try(Token.EQUAL)
if not tok:
return obj
error = self.parser.synassert(
isinstance(obj, AccessExpr),
"Se esperaba un objeto como destino de la asignación.")
if type(error) is Error:
return error
# Expresión
expr = self.expr()
if type(expr) is Error:
return expr
return AssignExpr(_object = obj,
value = expr)
# WIP
def binarithm(self, lvalue: Expr, i: int) -> (Expr | Error):
_lvalue = lvalue
if not lvalue:
_lvalue = self.cast(lvalue)
if type(_lvalue) is Error:
return _lvalue
tok = self.parser.lex()
j: int = self.precedence(tok.tipo)
while j >= i:
op = self.binop_for_tok(tok.tipo)
rvalue = self.cast(_lvalue)
if type(rvalue) is Error:
return rvalue
tok = self.parser.lex()
k: int = self.precedence(tok.tipo)
while k > j:
self.parser.unlex()
rvalue = self.binarithm(rvalue, k)
if type(rvalue) is Error:
return rvalue
tok = self.parser.lex()
k = self.precedence(tok.tipo)
_lvalue = BinarithmExpr(op = op,
lvalue = _lvalue,
rvalue = rvalue)
j = self.precedence(tok.tipo)
self.parser.unlex()
return _lvalue
def call(self, lvalue: Expr) -> (Expr | Error):
args: List[Expr] = []
while not self.parser._try(Token.R_PAREN):
# Expresión
expr = self.expr()
if type(expr) is Error:
return epr
args.append(expr)
# ,
if self.parser._try(Token.COMMA):
continue
# )
if self.parser._try(Token.R_PAREN):
break
return CallExpr(lvalue = lvalue,
args = args)
def compound_expr(self) -> (Expr | Error):
items: List[Expr] = []
# {
lbracket = self.parser.want(Token.L_BRACKET)
if type(lbracket) is Error:
return lbracket
while True:
# }
item = self.parser.peek(Token.R_BRACKET)
if item: break
# Expresión
item = self.expr()
if type(item) is Error:
return item
items.append(item)
# ;
semicolon = self.parser.want(Token.SEMICOLON)
if type(semicolon) is Error:
return semicolon
# }
rbracket = self.parser.want(Token.R_BRACKET)
if type(rbracket) is Error:
return rbracket
return CompoundExpr(exprs = items)
def builtin(self) -> (Expr | Error):
tok: LexToken = self.parser.peek(Token.PRINT, Token.READ)
if not tok:
return self.postfix(None)
if tok.tipo == Token.PRINT:
return self.print_expr()
elif tok.tipo == Token.READ:
return self.read_expr()
def postfix(self, lvalue: Optional[Expr]) -> (Expr | Error):
_lvalue: Optional[Expr] = lvalue
if not lvalue:
_lvalue = self.plain_expression()
if type(_lvalue) == Error:
return _lvalue
tok: LexToken = self.parser._try(Token.L_PAREN)
if not tok:
return _lvalue
_next: Optional[LexToken] = None
if tok.tipo == Token.L_PAREN:
return self.call(_lvalue)
return self.postfix(_next)
def print_expr(self) -> (Expr | Error):
_print = self.parser.want(Token.PRINT)
if type(_print) is Error:
return _print
lparen = self.parser.want(Token.L_PAREN)
if type(lparen) is Error:
return lparen
expr = self.expr()
if type(expr) is Error:
return expr
rparen = self.parser.want(Token.R_PAREN)
if type(rparen) is Error:
return rparen
return PrintExpr(expr = expr)
def read_expr(self) -> (Expr | Error):
_read = self.parser.want(Token.READ)
if type(_read) is Error:
return _read
ident = ParseIdent(self.parser).ident()
if type(ident) is Error:
return ident
return ReadExpr(expr = ident)
# WIP
def cast(self, lvalue: Optional[Expr]) -> (Expr | Error):
return self.unarithm()
# WIP
def constant(self) -> (Expr | Error):
tok: LexToken = self.parser.lex()
expr: Optional[ConstantExpr] = None
if tok.tipo == Token.STRING_LIT:
expr: str = tok.valor
elif tok.tipo == Token.INT_LIT:
expr = NumberConstant(value = tok.valor)
elif tok.tipo == Token.BOOLEAN_LIT:
expr: bool = tok.valor
else:
return Error(msg = "Se esperaba una constante.", numlinea = tok.numlinea)
return expr
# WIP
def plain_expression(self) -> (Expr | Error):
tok: LexToken = self.parser.peek()
if tok.tipo in [Token.BOOLEAN_LIT, Token.CHAR_LIT, Token.INT_LIT, Token.STRING_LIT]:
return self.constant()
elif tok.tipo == Token.L_PAREN:
lparen = self.parser.want(Token.L_PAREN)
if type(lparen) is Error:
return lparen
expr = self.expr()
if type(expr) is Error:
return expr
rparen = self.parser.want(Token.R_PAREN)
if type(rparen) is Error:
return rparen
return expr
elif tok.tipo == Token.IDENT:
ident = ParseIdent(self.parser).ident()
if type(ident) is Error:
return ident
return ident
def unarithm(self) -> (Expr | Error):
return self.builtin()
def binop_for_tok(self, tok: Token) -> (BinarithmOp | NoReturn):
if tok is Token.SLASH:
return BinarithmOp.DIV
elif tok is Token.GT:
return BinarithmOp.GT
elif tok is Token.GEQ:
return BinarithmOp.GTEQ
elif tok is Token.EQEQ:
return BinarithmOp.LEQUAL
elif tok is Token.LT:
return BinarithmOp.LESS
elif tok is Token.LEQ:
return BinarithmOp.LESSEQ
elif tok is Token.MINUS:
return BinarithmOp.MINUS
elif tok is Token.NOTEQ:
return BinarithmOp.NEQUAL
elif tok is Token.PLUS:
return BinarithmOp.PLUS
elif tok is Token.TIMES:
return BinarithmOp.TIMES
def precedence(self, tok: Token) -> int:
if tok in [Token.EQEQ, Token.NOTEQ]:
return 0
elif tok in [Token.PLUS, Token.MINUS]:
return 1
elif tok in [Token.TIMES, Token.SLASH]:
return 2
return -1
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