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const eval: implement ! for integers

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This commit is contained in:
Georg Brandl 2015-08-17 16:45:50 +02:00
parent 26f17e8c4a
commit a2dcbfea65
1 changed files with 41 additions and 10 deletions
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51
src/consts.rs
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@ -105,7 +105,7 @@ impl PartialEq for ConstantVariant {
match (self, other) {
(&ConstantStr(ref ls, ref lsty), &ConstantStr(ref rs, ref rsty)) =>
ls == rs && lsty == rsty,
(&ConstantBinary(ref l),&ConstantBinary(ref r)) => l == r,
(&ConstantBinary(ref l), &ConstantBinary(ref r)) => l == r,
(&ConstantByte(l), &ConstantByte(r)) => l == r,
(&ConstantChar(l), &ConstantChar(r)) => l == r,
(&ConstantInt(lv, lty), &ConstantInt(rv, rty)) => lv == rv &&
@ -184,13 +184,7 @@ pub fn constant(cx: &Context, e: &Expr) -> Option<Constant> {
Some(ConstantRepeat(Box::new(v), n.as_u64() as usize))),
&ExprUnary(op, ref operand) => constant(cx, operand).and_then(
|o| match op {
UnNot =>
if let ConstantBool(b) = o.constant {
Some(Constant{
needed_resolution: o.needed_resolution,
constant: ConstantBool(!b),
})
} else { None },
UnNot => constant_not(o),
UnNeg => constant_negate(o),
UnUniq | UnDeref => Some(o),
}),
@ -227,7 +221,7 @@ fn constant_vec<E: Deref<Target=Expr> + Sized>(cx: &Context, vec: &[E]) -> Optio
for opt_part in vec {
match constant(cx, opt_part) {
Some(p) => {
resolved |= (&p).needed_resolution;
resolved |= p.needed_resolution;
parts.push(p)
},
None => { return None; },
@ -245,7 +239,7 @@ fn constant_tup<E: Deref<Target=Expr> + Sized>(cx: &Context, tup: &[E]) -> Optio
for opt_part in tup {
match constant(cx, opt_part) {
Some(p) => {
resolved |= (&p).needed_resolution;
resolved |= p.needed_resolution;
parts.push(p)
},
None => { return None; },
@ -289,6 +283,43 @@ fn constant_if(cx: &Context, cond: &Expr, then: &Block, otherwise:
} else { None }
}
fn constant_not(o: Constant) -> Option<Constant> {
Some(Constant {
needed_resolution: o.needed_resolution,
constant: match o.constant {
ConstantBool(b) => ConstantBool(!b),
ConstantInt(value, ty) => {
let (nvalue, nty) = match ty {
SignedIntLit(ity, Plus) => {
if value == ::std::u64::MAX { return None; }
(value + 1, SignedIntLit(ity, Minus))
},
SignedIntLit(ity, Minus) => {
if value == 0 {
(1, SignedIntLit(ity, Minus))
} else {
(value - 1, SignedIntLit(ity, Plus))
}
}
UnsignedIntLit(ity) => {
let mask = match ity {
UintTy::TyU8 => ::std::u8::MAX as u64,
UintTy::TyU16 => ::std::u16::MAX as u64,
UintTy::TyU32 => ::std::u32::MAX as u64,
UintTy::TyU64 => ::std::u64::MAX,
UintTy::TyUs => { return None; } // refuse to guess
};
(!value & mask, UnsignedIntLit(ity))
}
UnsuffixedIntLit(_) => { return None; } // refuse to guess
};
ConstantInt(nvalue, nty)
},
_ => { return None; }
}
})
}
fn constant_negate(o: Constant) -> Option<Constant> {
Some(Constant{
needed_resolution: o.needed_resolution,