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#![allow(cast_possible_truncation)]
use rustc::lint::LateContext;
use rustc::hir::def::Def;
use rustc_const_eval::lookup_const_by_id;
use rustc_const_math::{ConstInt, ConstUsize, ConstIsize};
use rustc::hir::*;
use std::cmp::Ordering::{self, Equal};
use std::cmp::PartialOrd;
use std::hash::{Hash, Hasher};
use std::mem;
use std::rc::Rc;
use syntax::ast::{FloatTy, LitIntType, LitKind, StrStyle, UintTy, IntTy, NodeId};
use syntax::ptr::P;
#[derive(Debug, Copy, Clone)]
pub enum FloatWidth {
F32,
F64,
Any,
}
impl From<FloatTy> for FloatWidth {
fn from(ty: FloatTy) -> FloatWidth {
match ty {
FloatTy::F32 => FloatWidth::F32,
FloatTy::F64 => FloatWidth::F64,
}
}
}
#[derive(Debug, Clone)]
pub enum Constant {
Str(String, StrStyle),
Binary(Rc<Vec<u8>>),
Char(char),
Int(ConstInt),
Float(String, FloatWidth),
Bool(bool),
Vec(Vec<Constant>),
Repeat(Box<Constant>, usize),
Tuple(Vec<Constant>),
}
impl Constant {
fn as_u64(&self) -> u64 {
if let Constant::Int(val) = *self {
val.to_u64().expect("negative constant can't be casted to `u64`")
} else {
panic!("Could not convert a `{:?}` to `u64`", self);
}
}
}
impl PartialEq for Constant {
fn eq(&self, other: &Constant) -> bool {
match (self, other) {
(&Constant::Str(ref ls, ref l_sty), &Constant::Str(ref rs, ref r_sty)) => ls == rs && l_sty == r_sty,
(&Constant::Binary(ref l), &Constant::Binary(ref r)) => l == r,
(&Constant::Char(l), &Constant::Char(r)) => l == r,
(&Constant::Int(l), &Constant::Int(r)) => {
l.is_negative() == r.is_negative() && l.to_u128_unchecked() == r.to_u128_unchecked()
},
(&Constant::Float(ref ls, _), &Constant::Float(ref rs, _)) => {
match (ls.parse::<f64>(), rs.parse::<f64>()) {
(Ok(l), Ok(r)) => unsafe { mem::transmute::<f64, u64>(l) == mem::transmute::<f64, u64>(r) },
_ => false,
}
},
(&Constant::Bool(l), &Constant::Bool(r)) => l == r,
(&Constant::Vec(ref l), &Constant::Vec(ref r)) => l == r,
(&Constant::Repeat(ref lv, ref ls), &Constant::Repeat(ref rv, ref rs)) => ls == rs && lv == rv,
(&Constant::Tuple(ref l), &Constant::Tuple(ref r)) => l == r,
_ => false,
}
}
}
impl Hash for Constant {
fn hash<H>(&self, state: &mut H)
where H: Hasher
{
match *self {
Constant::Str(ref s, ref k) => {
s.hash(state);
k.hash(state);
},
Constant::Binary(ref b) => {
b.hash(state);
},
Constant::Char(c) => {
c.hash(state);
},
Constant::Int(i) => {
i.to_u128_unchecked().hash(state);
i.is_negative().hash(state);
},
Constant::Float(ref f, _) => {
if let Ok(f) = f.parse::<f64>() {
unsafe { mem::transmute::<f64, u64>(f) }.hash(state);
}
},
Constant::Bool(b) => {
b.hash(state);
},
Constant::Vec(ref v) |
Constant::Tuple(ref v) => {
v.hash(state);
},
Constant::Repeat(ref c, l) => {
c.hash(state);
l.hash(state);
},
}
}
}
impl PartialOrd for Constant {
fn partial_cmp(&self, other: &Constant) -> Option<Ordering> {
match (self, other) {
(&Constant::Str(ref ls, ref l_sty), &Constant::Str(ref rs, ref r_sty)) => {
if l_sty == r_sty {
Some(ls.cmp(rs))
} else {
None
}
},
(&Constant::Char(ref l), &Constant::Char(ref r)) => Some(l.cmp(r)),
(&Constant::Int(l), &Constant::Int(r)) => Some(l.cmp(&r)),
(&Constant::Float(ref ls, _), &Constant::Float(ref rs, _)) => {
match (ls.parse::<f64>(), rs.parse::<f64>()) {
(Ok(ref l), Ok(ref r)) => {
match (l.partial_cmp(r), l.is_sign_positive() == r.is_sign_positive()) {
(Some(Ordering::Equal), false) => None,
(x, _) => x,
}
},
_ => None,
}
},
(&Constant::Bool(ref l), &Constant::Bool(ref r)) => Some(l.cmp(r)),
(&Constant::Tuple(ref l), &Constant::Tuple(ref r)) |
(&Constant::Vec(ref l), &Constant::Vec(ref r)) => l.partial_cmp(r),
(&Constant::Repeat(ref lv, ref ls), &Constant::Repeat(ref rv, ref rs)) => {
match lv.partial_cmp(rv) {
Some(Equal) => Some(ls.cmp(rs)),
x => x,
}
},
_ => None,
}
}
}
#[allow(cast_possible_wrap)]
pub fn lit_to_constant(lit: &LitKind) -> Constant {
match *lit {
LitKind::Str(ref is, style) => Constant::Str(is.to_string(), style),
LitKind::Byte(b) => Constant::Int(ConstInt::U8(b)),
LitKind::ByteStr(ref s) => Constant::Binary(s.clone()),
LitKind::Char(c) => Constant::Char(c),
LitKind::Int(value, LitIntType::Unsuffixed) => Constant::Int(ConstInt::Infer(value)),
LitKind::Int(value, LitIntType::Unsigned(UintTy::U8)) => Constant::Int(ConstInt::U8(value as u8)),
LitKind::Int(value, LitIntType::Unsigned(UintTy::U16)) => Constant::Int(ConstInt::U16(value as u16)),
LitKind::Int(value, LitIntType::Unsigned(UintTy::U32)) => Constant::Int(ConstInt::U32(value as u32)),
LitKind::Int(value, LitIntType::Unsigned(UintTy::U64)) => Constant::Int(ConstInt::U64(value as u64)),
LitKind::Int(value, LitIntType::Unsigned(UintTy::U128)) => Constant::Int(ConstInt::U128(value as u128)),
LitKind::Int(value, LitIntType::Unsigned(UintTy::Us)) => {
Constant::Int(ConstInt::Usize(ConstUsize::Us32(value as u32)))
},
LitKind::Int(value, LitIntType::Signed(IntTy::I8)) => Constant::Int(ConstInt::I8(value as i8)),
LitKind::Int(value, LitIntType::Signed(IntTy::I16)) => Constant::Int(ConstInt::I16(value as i16)),
LitKind::Int(value, LitIntType::Signed(IntTy::I32)) => Constant::Int(ConstInt::I32(value as i32)),
LitKind::Int(value, LitIntType::Signed(IntTy::I64)) => Constant::Int(ConstInt::I64(value as i64)),
LitKind::Int(value, LitIntType::Signed(IntTy::I128)) => Constant::Int(ConstInt::I128(value as i128)),
LitKind::Int(value, LitIntType::Signed(IntTy::Is)) => {
Constant::Int(ConstInt::Isize(ConstIsize::Is32(value as i32)))
},
LitKind::Float(ref is, ty) => Constant::Float(is.to_string(), ty.into()),
LitKind::FloatUnsuffixed(ref is) => Constant::Float(is.to_string(), FloatWidth::Any),
LitKind::Bool(b) => Constant::Bool(b),
}
}
fn constant_not(o: Constant) -> Option<Constant> {
use self::Constant::*;
match o {
Bool(b) => Some(Bool(!b)),
Int(value) => (!value).ok().map(Int),
_ => None,
}
}
fn constant_negate(o: Constant) -> Option<Constant> {
use self::Constant::*;
match o {
Int(value) => (-value).ok().map(Int),
Float(is, ty) => Some(Float(neg_float_str(is), ty)),
_ => None,
}
}
fn neg_float_str(s: String) -> String {
if s.starts_with('-') {
s[1..].to_owned()
} else {
format!("-{}", s)
}
}
pub fn constant(lcx: &LateContext, e: &Expr) -> Option<(Constant, bool)> {
let mut cx = ConstEvalLateContext {
lcx: Some(lcx),
needed_resolution: false,
};
cx.expr(e).map(|cst| (cst, cx.needed_resolution))
}
pub fn constant_simple(e: &Expr) -> Option<Constant> {
let mut cx = ConstEvalLateContext {
lcx: None,
needed_resolution: false,
};
cx.expr(e)
}
struct ConstEvalLateContext<'c, 'cc: 'c> {
lcx: Option<&'c LateContext<'c, 'cc>>,
needed_resolution: bool,
}
impl<'c, 'cc> ConstEvalLateContext<'c, 'cc> {
fn expr(&mut self, e: &Expr) -> Option<Constant> {
match e.node {
ExprPath(ref qpath) => self.fetch_path(qpath, e.id),
ExprBlock(ref block) => self.block(block),
ExprIf(ref cond, ref then, ref otherwise) => self.ifthenelse(cond, then, otherwise),
ExprLit(ref lit) => Some(lit_to_constant(&lit.node)),
ExprArray(ref vec) => self.multi(vec).map(Constant::Vec),
ExprTup(ref tup) => self.multi(tup).map(Constant::Tuple),
ExprRepeat(ref value, number_id) => {
if let Some(lcx) = self.lcx {
self.binop_apply(value,
&lcx.tcx.map.body(number_id).value,
|v, n| Some(Constant::Repeat(Box::new(v), n.as_u64() as usize)))
} else {
None
}
},
ExprUnary(op, ref operand) => {
self.expr(operand).and_then(|o| {
match op {
UnNot => constant_not(o),
UnNeg => constant_negate(o),
UnDeref => Some(o),
}
})
},
ExprBinary(op, ref left, ref right) => self.binop(op, left, right),
_ => None,
}
}
fn multi(&mut self, vec: &[Expr]) -> Option<Vec<Constant>> {
vec.iter()
.map(|elem| self.expr(elem))
.collect::<Option<_>>()
}
fn fetch_path(&mut self, qpath: &QPath, id: NodeId) -> Option<Constant> {
if let Some(lcx) = self.lcx {
let def = lcx.tcx.tables().qpath_def(qpath, id);
match def {
Def::Const(def_id) |
Def::AssociatedConst(def_id) => {
let substs = Some(lcx.tcx
.tables()
.node_id_item_substs(id)
.unwrap_or_else(|| lcx.tcx.intern_substs(&[])));
if let Some((const_expr, _ty)) = lookup_const_by_id(lcx.tcx, def_id, substs) {
let ret = self.expr(const_expr);
if ret.is_some() {
self.needed_resolution = true;
}
return ret;
}
},
_ => {},
}
}
None
}
fn block(&mut self, block: &Block) -> Option<Constant> {
if block.stmts.is_empty() {
block.expr.as_ref().and_then(|b| self.expr(b))
} else {
None
}
}
fn ifthenelse(&mut self, cond: &Expr, then: &Block, otherwise: &Option<P<Expr>>) -> Option<Constant> {
if let Some(Constant::Bool(b)) = self.expr(cond) {
if b {
self.block(then)
} else {
otherwise.as_ref().and_then(|expr| self.expr(expr))
}
} else {
None
}
}
fn binop(&mut self, op: BinOp, left: &Expr, right: &Expr) -> Option<Constant> {
let l = if let Some(l) = self.expr(left) {
l
} else {
return None;
};
let r = self.expr(right);
match (op.node, l, r) {
(BiAdd, Constant::Int(l), Some(Constant::Int(r))) => (l + r).ok().map(Constant::Int),
(BiSub, Constant::Int(l), Some(Constant::Int(r))) => (l - r).ok().map(Constant::Int),
(BiMul, Constant::Int(l), Some(Constant::Int(r))) => (l * r).ok().map(Constant::Int),
(BiDiv, Constant::Int(l), Some(Constant::Int(r))) => (l / r).ok().map(Constant::Int),
(BiRem, Constant::Int(l), Some(Constant::Int(r))) => (l % r).ok().map(Constant::Int),
(BiAnd, Constant::Bool(false), _) => Some(Constant::Bool(false)),
(BiOr, Constant::Bool(true), _) => Some(Constant::Bool(true)),
(BiAnd, Constant::Bool(true), Some(r)) |
(BiOr, Constant::Bool(false), Some(r)) => Some(r),
(BiBitXor, Constant::Bool(l), Some(Constant::Bool(r))) => Some(Constant::Bool(l ^ r)),
(BiBitXor, Constant::Int(l), Some(Constant::Int(r))) => (l ^ r).ok().map(Constant::Int),
(BiBitAnd, Constant::Bool(l), Some(Constant::Bool(r))) => Some(Constant::Bool(l & r)),
(BiBitAnd, Constant::Int(l), Some(Constant::Int(r))) => (l & r).ok().map(Constant::Int),
(BiBitOr, Constant::Bool(l), Some(Constant::Bool(r))) => Some(Constant::Bool(l | r)),
(BiBitOr, Constant::Int(l), Some(Constant::Int(r))) => (l | r).ok().map(Constant::Int),
(BiShl, Constant::Int(l), Some(Constant::Int(r))) => (l << r).ok().map(Constant::Int),
(BiShr, Constant::Int(l), Some(Constant::Int(r))) => (l >> r).ok().map(Constant::Int),
(BiEq, Constant::Int(l), Some(Constant::Int(r))) => Some(Constant::Bool(l == r)),
(BiNe, Constant::Int(l), Some(Constant::Int(r))) => Some(Constant::Bool(l != r)),
(BiLt, Constant::Int(l), Some(Constant::Int(r))) => Some(Constant::Bool(l < r)),
(BiLe, Constant::Int(l), Some(Constant::Int(r))) => Some(Constant::Bool(l <= r)),
(BiGe, Constant::Int(l), Some(Constant::Int(r))) => Some(Constant::Bool(l >= r)),
(BiGt, Constant::Int(l), Some(Constant::Int(r))) => Some(Constant::Bool(l > r)),
_ => None,
}
}
fn binop_apply<F>(&mut self, left: &Expr, right: &Expr, op: F) -> Option<Constant>
where F: Fn(Constant, Constant) -> Option<Constant>
{
if let (Some(lc), Some(rc)) = (self.expr(left), self.expr(right)) {
op(lc, rc)
} else {
None
}
}
}