def simpleExpression():
"""
Parses
simpleExpression = ["+" | "-"] term {("+" | "-" | "or") term}.
Generates code for the simpleExpression if no error is reported
"""
if SC.sym == PLUS:
getSym(); x = term()
elif SC.sym == MINUS:
getSym(); x = term()
if x.tp != Int: mark('bad type')
elif type(x) == Const: x.val = - x.val # constant folding
else: x = genUnaryOp(MINUS, x)
else: x = term()
while SC.sym in {PLUS, MINUS, OR}:
op = SC.sym; getSym()
if op == OR and type(x) != Const: x = genUnaryOp(OR, x)
y = term() # x op y
if x.tp == Int == y.tp and op in {PLUS, MINUS}:
if type(x) == Const == type(y): # constant folding
if op == PLUS: x.val = x.val + y.val
elif op == MINUS: x.val = x.val - y.val
else: x = genBinaryOp(op, x, y)
elif x.tp == Bool == y.tp and op == OR:
if type(x) == Const: # constant folding
if not x.val: x = y # if x is false, take y, else x
else: x = genBinaryOp(OR, x, y)
else: mark('bad type')
return x
def simpleExpression():
"""
Parses
simpleExpression = ["+" | "-"] term {("+" | "-" | "or") term}.
Generates code for the simpleExpression if no error is reported
"""
if SC.sym == PLUS:
getSym()
x = term()
elif SC.sym == MINUS:
getSym()
x = term()
if x.tp != Int:
mark("bad type")
elif type(x) == Const:
x.val = -x.val # constant folding
else:
x = genUnaryOp(MINUS, x)
else:
x = term()
while SC.sym in {PLUS, MINUS, OR}:
op = SC.sym
getSym()
if op == OR and type(x) != Const:
x = genUnaryOp(OR, x) # -----
y = term() # x op y
if x.tp == Int == y.tp and op in {PLUS, MINUS}: # if (type(x)=int and type(y)=int) and (operator is + or -)
if type(x) == Const == type(y): # constant folding
## does x + y if they are not zero
if op == PLUS:
x.val = x.val + y.val
elif op == MINUS:
x.val = x.val - y.val
else:
print("op", op)
print("1. simpleExpression")
if type(x).__name__ == "Const" and x.val == 0:
x = y
print("x = y")
continue
elif type(y).__name__ == "Const" and y.val == 0:
print("x = x")
x = x
continue
x = genBinaryOp(op, x, y) # does the arithmetic + and minus
elif x.tp == Bool == y.tp and op == OR: # no changes past here
if type(x) == Const: # constant folding
if not x.val:
x = y # if x is false, take y, else x
else:
x = genBinaryOp(OR, x, y)
else:
mark("bad type")
writeln("TEST: ", "SimpleExpression: ", "5. ", "ended")
# print("--- x: ", dir(x));
print("function ending x: ", vars(x))
return x
def factor():
"""
Parses
factor = ident selector | integer | "(" expression ")" | "not" factor.
Generates code for the factor if no error is reported
"""
if SC.sym not in FIRSTFACTOR:
mark("factor expected"); getSym()
while SC.sym not in FIRSTFACTOR | STRONGSYMS | FOLLOWFACTOR:
getSym()
if SC.sym == IDENT:
x = find(SC.val)
if type(x) in {Var, Ref}: x = genVar(x)
elif type(x) == Const: x = Const(x.tp, x.val); x = genConst(x)
else: mark('variable or constant expected')
getSym(); x = selector(x)
elif SC.sym == NUMBER:
x = Const(Int, SC.val); x = genConst(x); getSym()
elif SC.sym == LPAREN:
getSym(); x = expression()
if SC.sym == RPAREN: getSym()
else: mark(") expected")
elif SC.sym == NOT:
getSym(); x = factor()
if x.tp != Bool: mark('not boolean')
elif type(x) == Const: x.val = 1 - x.val # constant folding
else: x = genUnaryOp(NOT, x)
else:
mark("factor expected"); x = None
return x
def term():
"""
Parses
term = factor {("*" | "div" | "mod" | "and") factor}.
Generates code for the term if no error is reported
"""
x = factor()
while SC.sym in {TIMES, DIV, MOD, AND}:
op = SC.sym
getSym()
if op == AND and type(x) != Const:
x = genUnaryOp(AND, x)
y = factor() # x op y
if x.tp == Int == y.tp and op in {TIMES, DIV, MOD}:
if type(x) == Const == type(y): # constant folding
if op == TIMES:
x.val = x.val * y.val
elif op == DIV:
x.val = x.val // y.val
elif op == MOD:
x.val = x.val % y.val
else:
print("term 2: start optimization op", op)
if type(x).__name__ == "Const" and x.val == 1: # check if x=1 for multiplications
print("x == 1, do not multiply by 1")
x = y
elif type(y).__name__ == "Const" and y.val == 1: # check for imediate for multiplications
print("y == 1, do not multiply by 1")
x = x
else:
x = genBinaryOp(op, x, y)
elif x.tp == Bool == y.tp and op == AND:
if type(x) == Const: # constant folding
if x.val:
x = y # if x is true, take y, else x
else:
x = genBinaryOp(AND, x, y)
else:
mark("bad type")
return x
def term():
"""
Parses
term = factor {("*" | "div" | "mod" | "and") factor}.
Generates code for the term if no error is reported
"""
x = factor()
while SC.sym in {TIMES, DIV, MOD, AND}:
op = SC.sym; getSym();
if op == AND and type(x) != Const: x = genUnaryOp(AND, x)
y = factor() # x op y
if x.tp == Int == y.tp and op in {TIMES, DIV, MOD}:
if type(x) == Const == type(y): # constant folding
if op == TIMES: x.val = x.val * y.val
elif op == DIV: x.val = x.val // y.val
elif op == MOD: x.val = x.val % y.val
else: x = genBinaryOp(op, x, y)
elif x.tp == Bool == y.tp and op == AND:
if type(x) == Const: # constant folding
if x.val: x = y # if x is true, take y, else x
else: x = genBinaryOp(AND, x, y)
else: mark('bad type')
return x