501 lines
20 KiB
Rust
501 lines
20 KiB
Rust
#![allow(clippy::float_cmp)]
|
||
|
||
use crate::utils::{clip, higher, sext, unsext};
|
||
use if_chain::if_chain;
|
||
use rustc::hir::def::{DefKind, Res};
|
||
use rustc::hir::*;
|
||
use rustc::lint::LateContext;
|
||
use rustc::ty::subst::{Subst, SubstsRef};
|
||
use rustc::ty::{self, Ty, TyCtxt};
|
||
use rustc::{bug, span_bug};
|
||
use rustc_data_structures::sync::Lrc;
|
||
use std::cmp::Ordering::{self, Equal};
|
||
use std::cmp::PartialOrd;
|
||
use std::convert::TryInto;
|
||
use std::hash::{Hash, Hasher};
|
||
use syntax::ast::{FloatTy, LitKind};
|
||
use syntax_pos::symbol::Symbol;
|
||
|
||
/// A `LitKind`-like enum to fold constant `Expr`s into.
|
||
#[derive(Debug, Clone)]
|
||
pub enum Constant {
|
||
/// A `String` (e.g., "abc").
|
||
Str(String),
|
||
/// A binary string (e.g., `b"abc"`).
|
||
Binary(Lrc<Vec<u8>>),
|
||
/// A single `char` (e.g., `'a'`).
|
||
Char(char),
|
||
/// An integer's bit representation.
|
||
Int(u128),
|
||
/// An `f32`.
|
||
F32(f32),
|
||
/// An `f64`.
|
||
F64(f64),
|
||
/// `true` or `false`.
|
||
Bool(bool),
|
||
/// An array of constants.
|
||
Vec(Vec<Constant>),
|
||
/// Also an array, but with only one constant, repeated N times.
|
||
Repeat(Box<Constant>, u64),
|
||
/// A tuple of constants.
|
||
Tuple(Vec<Constant>),
|
||
/// A raw pointer.
|
||
RawPtr(u128),
|
||
/// A literal with syntax error.
|
||
Err(Symbol),
|
||
}
|
||
|
||
impl PartialEq for Constant {
|
||
fn eq(&self, other: &Self) -> bool {
|
||
match (self, other) {
|
||
(&Self::Str(ref ls), &Self::Str(ref rs)) => ls == rs,
|
||
(&Self::Binary(ref l), &Self::Binary(ref r)) => l == r,
|
||
(&Self::Char(l), &Self::Char(r)) => l == r,
|
||
(&Self::Int(l), &Self::Int(r)) => l == r,
|
||
(&Self::F64(l), &Self::F64(r)) => {
|
||
// We want `Fw32 == FwAny` and `FwAny == Fw64`, and by transitivity we must have
|
||
// `Fw32 == Fw64`, so don’t compare them.
|
||
// `to_bits` is required to catch non-matching 0.0, -0.0, and NaNs.
|
||
l.to_bits() == r.to_bits()
|
||
},
|
||
(&Self::F32(l), &Self::F32(r)) => {
|
||
// We want `Fw32 == FwAny` and `FwAny == Fw64`, and by transitivity we must have
|
||
// `Fw32 == Fw64`, so don’t compare them.
|
||
// `to_bits` is required to catch non-matching 0.0, -0.0, and NaNs.
|
||
f64::from(l).to_bits() == f64::from(r).to_bits()
|
||
},
|
||
(&Self::Bool(l), &Self::Bool(r)) => l == r,
|
||
(&Self::Vec(ref l), &Self::Vec(ref r)) | (&Self::Tuple(ref l), &Self::Tuple(ref r)) => l == r,
|
||
(&Self::Repeat(ref lv, ref ls), &Self::Repeat(ref rv, ref rs)) => ls == rs && lv == rv,
|
||
// TODO: are there inter-type equalities?
|
||
_ => false,
|
||
}
|
||
}
|
||
}
|
||
|
||
impl Hash for Constant {
|
||
fn hash<H>(&self, state: &mut H)
|
||
where
|
||
H: Hasher,
|
||
{
|
||
std::mem::discriminant(self).hash(state);
|
||
match *self {
|
||
Self::Str(ref s) => {
|
||
s.hash(state);
|
||
},
|
||
Self::Binary(ref b) => {
|
||
b.hash(state);
|
||
},
|
||
Self::Char(c) => {
|
||
c.hash(state);
|
||
},
|
||
Self::Int(i) => {
|
||
i.hash(state);
|
||
},
|
||
Self::F32(f) => {
|
||
f64::from(f).to_bits().hash(state);
|
||
},
|
||
Self::F64(f) => {
|
||
f.to_bits().hash(state);
|
||
},
|
||
Self::Bool(b) => {
|
||
b.hash(state);
|
||
},
|
||
Self::Vec(ref v) | Self::Tuple(ref v) => {
|
||
v.hash(state);
|
||
},
|
||
Self::Repeat(ref c, l) => {
|
||
c.hash(state);
|
||
l.hash(state);
|
||
},
|
||
Self::RawPtr(u) => {
|
||
u.hash(state);
|
||
},
|
||
Self::Err(ref s) => {
|
||
s.hash(state);
|
||
},
|
||
}
|
||
}
|
||
}
|
||
|
||
impl Constant {
|
||
pub fn partial_cmp(tcx: TyCtxt<'_>, cmp_type: Ty<'_>, left: &Self, right: &Self) -> Option<Ordering> {
|
||
match (left, right) {
|
||
(&Self::Str(ref ls), &Self::Str(ref rs)) => Some(ls.cmp(rs)),
|
||
(&Self::Char(ref l), &Self::Char(ref r)) => Some(l.cmp(r)),
|
||
(&Self::Int(l), &Self::Int(r)) => {
|
||
if let ty::Int(int_ty) = cmp_type.kind {
|
||
Some(sext(tcx, l, int_ty).cmp(&sext(tcx, r, int_ty)))
|
||
} else {
|
||
Some(l.cmp(&r))
|
||
}
|
||
},
|
||
(&Self::F64(l), &Self::F64(r)) => l.partial_cmp(&r),
|
||
(&Self::F32(l), &Self::F32(r)) => l.partial_cmp(&r),
|
||
(&Self::Bool(ref l), &Self::Bool(ref r)) => Some(l.cmp(r)),
|
||
(&Self::Tuple(ref l), &Self::Tuple(ref r)) | (&Self::Vec(ref l), &Self::Vec(ref r)) => l
|
||
.iter()
|
||
.zip(r.iter())
|
||
.map(|(li, ri)| Self::partial_cmp(tcx, cmp_type, li, ri))
|
||
.find(|r| r.map_or(true, |o| o != Ordering::Equal))
|
||
.unwrap_or_else(|| Some(l.len().cmp(&r.len()))),
|
||
(&Self::Repeat(ref lv, ref ls), &Self::Repeat(ref rv, ref rs)) => {
|
||
match Self::partial_cmp(tcx, cmp_type, lv, rv) {
|
||
Some(Equal) => Some(ls.cmp(rs)),
|
||
x => x,
|
||
}
|
||
},
|
||
// TODO: are there any useful inter-type orderings?
|
||
_ => None,
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Parses a `LitKind` to a `Constant`.
|
||
pub fn lit_to_constant(lit: &LitKind, ty: Option<Ty<'_>>) -> Constant {
|
||
use syntax::ast::*;
|
||
|
||
match *lit {
|
||
LitKind::Str(ref is, _) => Constant::Str(is.to_string()),
|
||
LitKind::Byte(b) => Constant::Int(u128::from(b)),
|
||
LitKind::ByteStr(ref s) => Constant::Binary(Lrc::clone(s)),
|
||
LitKind::Char(c) => Constant::Char(c),
|
||
LitKind::Int(n, _) => Constant::Int(n),
|
||
LitKind::Float(ref is, LitFloatType::Suffixed(fty)) => match fty {
|
||
FloatTy::F32 => Constant::F32(is.as_str().parse().unwrap()),
|
||
FloatTy::F64 => Constant::F64(is.as_str().parse().unwrap()),
|
||
},
|
||
LitKind::Float(ref is, LitFloatType::Unsuffixed) => match ty.expect("type of float is known").kind {
|
||
ty::Float(FloatTy::F32) => Constant::F32(is.as_str().parse().unwrap()),
|
||
ty::Float(FloatTy::F64) => Constant::F64(is.as_str().parse().unwrap()),
|
||
_ => bug!(),
|
||
},
|
||
LitKind::Bool(b) => Constant::Bool(b),
|
||
LitKind::Err(s) => Constant::Err(s),
|
||
}
|
||
}
|
||
|
||
pub fn constant<'c, 'cc>(
|
||
lcx: &LateContext<'c, 'cc>,
|
||
tables: &'c ty::TypeckTables<'cc>,
|
||
e: &Expr,
|
||
) -> Option<(Constant, bool)> {
|
||
let mut cx = ConstEvalLateContext {
|
||
lcx,
|
||
tables,
|
||
param_env: lcx.param_env,
|
||
needed_resolution: false,
|
||
substs: lcx.tcx.intern_substs(&[]),
|
||
};
|
||
cx.expr(e).map(|cst| (cst, cx.needed_resolution))
|
||
}
|
||
|
||
pub fn constant_simple<'c, 'cc>(
|
||
lcx: &LateContext<'c, 'cc>,
|
||
tables: &'c ty::TypeckTables<'cc>,
|
||
e: &Expr,
|
||
) -> Option<Constant> {
|
||
constant(lcx, tables, e).and_then(|(cst, res)| if res { None } else { Some(cst) })
|
||
}
|
||
|
||
/// Creates a `ConstEvalLateContext` from the given `LateContext` and `TypeckTables`.
|
||
pub fn constant_context<'c, 'cc>(
|
||
lcx: &'c LateContext<'c, 'cc>,
|
||
tables: &'c ty::TypeckTables<'cc>,
|
||
) -> ConstEvalLateContext<'c, 'cc> {
|
||
ConstEvalLateContext {
|
||
lcx,
|
||
tables,
|
||
param_env: lcx.param_env,
|
||
needed_resolution: false,
|
||
substs: lcx.tcx.intern_substs(&[]),
|
||
}
|
||
}
|
||
|
||
pub struct ConstEvalLateContext<'a, 'tcx> {
|
||
lcx: &'a LateContext<'a, 'tcx>,
|
||
tables: &'a ty::TypeckTables<'tcx>,
|
||
param_env: ty::ParamEnv<'tcx>,
|
||
needed_resolution: bool,
|
||
substs: SubstsRef<'tcx>,
|
||
}
|
||
|
||
impl<'c, 'cc> ConstEvalLateContext<'c, 'cc> {
|
||
/// Simple constant folding: Insert an expression, get a constant or none.
|
||
pub fn expr(&mut self, e: &Expr) -> Option<Constant> {
|
||
if let Some((ref cond, ref then, otherwise)) = higher::if_block(&e) {
|
||
return self.ifthenelse(cond, then, otherwise);
|
||
}
|
||
match e.kind {
|
||
ExprKind::Path(ref qpath) => self.fetch_path(qpath, e.hir_id),
|
||
ExprKind::Block(ref block, _) => self.block(block),
|
||
ExprKind::Lit(ref lit) => Some(lit_to_constant(&lit.node, self.tables.expr_ty_opt(e))),
|
||
ExprKind::Array(ref vec) => self.multi(vec).map(Constant::Vec),
|
||
ExprKind::Tup(ref tup) => self.multi(tup).map(Constant::Tuple),
|
||
ExprKind::Repeat(ref value, _) => {
|
||
let n = match self.tables.expr_ty(e).kind {
|
||
ty::Array(_, n) => n.eval_usize(self.lcx.tcx, self.lcx.param_env),
|
||
_ => span_bug!(e.span, "typeck error"),
|
||
};
|
||
self.expr(value).map(|v| Constant::Repeat(Box::new(v), n))
|
||
},
|
||
ExprKind::Unary(op, ref operand) => self.expr(operand).and_then(|o| match op {
|
||
UnNot => self.constant_not(&o, self.tables.expr_ty(e)),
|
||
UnNeg => self.constant_negate(&o, self.tables.expr_ty(e)),
|
||
UnDeref => Some(o),
|
||
}),
|
||
ExprKind::Binary(op, ref left, ref right) => self.binop(op, left, right),
|
||
ExprKind::Call(ref callee, ref args) => {
|
||
// We only handle a few const functions for now.
|
||
if_chain! {
|
||
if args.is_empty();
|
||
if let ExprKind::Path(qpath) = &callee.kind;
|
||
let res = self.tables.qpath_res(qpath, callee.hir_id);
|
||
if let Some(def_id) = res.opt_def_id();
|
||
let def_path: Vec<_> = self.lcx.get_def_path(def_id).into_iter().map(Symbol::as_str).collect();
|
||
let def_path: Vec<&str> = def_path.iter().take(4).map(|s| &**s).collect();
|
||
if let ["core", "num", int_impl, "max_value"] = *def_path;
|
||
then {
|
||
let value = match int_impl {
|
||
"<impl i8>" => i8::max_value() as u128,
|
||
"<impl i16>" => i16::max_value() as u128,
|
||
"<impl i32>" => i32::max_value() as u128,
|
||
"<impl i64>" => i64::max_value() as u128,
|
||
"<impl i128>" => i128::max_value() as u128,
|
||
_ => return None,
|
||
};
|
||
Some(Constant::Int(value))
|
||
}
|
||
else {
|
||
None
|
||
}
|
||
}
|
||
},
|
||
// TODO: add other expressions.
|
||
_ => None,
|
||
}
|
||
}
|
||
|
||
#[allow(clippy::cast_possible_wrap)]
|
||
fn constant_not(&self, o: &Constant, ty: Ty<'_>) -> Option<Constant> {
|
||
use self::Constant::*;
|
||
match *o {
|
||
Bool(b) => Some(Bool(!b)),
|
||
Int(value) => {
|
||
let value = !value;
|
||
match ty.kind {
|
||
ty::Int(ity) => Some(Int(unsext(self.lcx.tcx, value as i128, ity))),
|
||
ty::Uint(ity) => Some(Int(clip(self.lcx.tcx, value, ity))),
|
||
_ => None,
|
||
}
|
||
},
|
||
_ => None,
|
||
}
|
||
}
|
||
|
||
fn constant_negate(&self, o: &Constant, ty: Ty<'_>) -> Option<Constant> {
|
||
use self::Constant::*;
|
||
match *o {
|
||
Int(value) => {
|
||
let ity = match ty.kind {
|
||
ty::Int(ity) => ity,
|
||
_ => return None,
|
||
};
|
||
// sign extend
|
||
let value = sext(self.lcx.tcx, value, ity);
|
||
let value = value.checked_neg()?;
|
||
// clear unused bits
|
||
Some(Int(unsext(self.lcx.tcx, value, ity)))
|
||
},
|
||
F32(f) => Some(F32(-f)),
|
||
F64(f) => Some(F64(-f)),
|
||
_ => None,
|
||
}
|
||
}
|
||
|
||
/// Create `Some(Vec![..])` of all constants, unless there is any
|
||
/// non-constant part.
|
||
fn multi(&mut self, vec: &[Expr]) -> Option<Vec<Constant>> {
|
||
vec.iter().map(|elem| self.expr(elem)).collect::<Option<_>>()
|
||
}
|
||
|
||
/// Lookup a possibly constant expression from a `ExprKind::Path`.
|
||
fn fetch_path(&mut self, qpath: &QPath, id: HirId) -> Option<Constant> {
|
||
let res = self.tables.qpath_res(qpath, id);
|
||
match res {
|
||
Res::Def(DefKind::Const, def_id) | Res::Def(DefKind::AssocConst, def_id) => {
|
||
let substs = self.tables.node_substs(id);
|
||
let substs = if self.substs.is_empty() {
|
||
substs
|
||
} else {
|
||
substs.subst(self.lcx.tcx, self.substs)
|
||
};
|
||
|
||
let result = self
|
||
.lcx
|
||
.tcx
|
||
.const_eval_resolve(self.param_env, def_id, substs, None)
|
||
.ok()?;
|
||
let result = miri_to_const(&result);
|
||
if result.is_some() {
|
||
self.needed_resolution = true;
|
||
}
|
||
result
|
||
},
|
||
// FIXME: cover all usable cases.
|
||
_ => None,
|
||
}
|
||
}
|
||
|
||
/// A block can only yield a constant if it only has one constant expression.
|
||
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: &Expr, otherwise: Option<&Expr>) -> Option<Constant> {
|
||
if let Some(Constant::Bool(b)) = self.expr(cond) {
|
||
if b {
|
||
self.expr(&*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 = self.expr(left)?;
|
||
let r = self.expr(right);
|
||
match (l, r) {
|
||
(Constant::Int(l), Some(Constant::Int(r))) => match self.tables.expr_ty(left).kind {
|
||
ty::Int(ity) => {
|
||
let l = sext(self.lcx.tcx, l, ity);
|
||
let r = sext(self.lcx.tcx, r, ity);
|
||
let zext = |n: i128| Constant::Int(unsext(self.lcx.tcx, n, ity));
|
||
match op.node {
|
||
BinOpKind::Add => l.checked_add(r).map(zext),
|
||
BinOpKind::Sub => l.checked_sub(r).map(zext),
|
||
BinOpKind::Mul => l.checked_mul(r).map(zext),
|
||
BinOpKind::Div if r != 0 => l.checked_div(r).map(zext),
|
||
BinOpKind::Rem if r != 0 => l.checked_rem(r).map(zext),
|
||
BinOpKind::Shr => l.checked_shr(r.try_into().expect("invalid shift")).map(zext),
|
||
BinOpKind::Shl => l.checked_shl(r.try_into().expect("invalid shift")).map(zext),
|
||
BinOpKind::BitXor => Some(zext(l ^ r)),
|
||
BinOpKind::BitOr => Some(zext(l | r)),
|
||
BinOpKind::BitAnd => Some(zext(l & r)),
|
||
BinOpKind::Eq => Some(Constant::Bool(l == r)),
|
||
BinOpKind::Ne => Some(Constant::Bool(l != r)),
|
||
BinOpKind::Lt => Some(Constant::Bool(l < r)),
|
||
BinOpKind::Le => Some(Constant::Bool(l <= r)),
|
||
BinOpKind::Ge => Some(Constant::Bool(l >= r)),
|
||
BinOpKind::Gt => Some(Constant::Bool(l > r)),
|
||
_ => None,
|
||
}
|
||
},
|
||
ty::Uint(_) => match op.node {
|
||
BinOpKind::Add => l.checked_add(r).map(Constant::Int),
|
||
BinOpKind::Sub => l.checked_sub(r).map(Constant::Int),
|
||
BinOpKind::Mul => l.checked_mul(r).map(Constant::Int),
|
||
BinOpKind::Div => l.checked_div(r).map(Constant::Int),
|
||
BinOpKind::Rem => l.checked_rem(r).map(Constant::Int),
|
||
BinOpKind::Shr => l.checked_shr(r.try_into().expect("shift too large")).map(Constant::Int),
|
||
BinOpKind::Shl => l.checked_shl(r.try_into().expect("shift too large")).map(Constant::Int),
|
||
BinOpKind::BitXor => Some(Constant::Int(l ^ r)),
|
||
BinOpKind::BitOr => Some(Constant::Int(l | r)),
|
||
BinOpKind::BitAnd => Some(Constant::Int(l & r)),
|
||
BinOpKind::Eq => Some(Constant::Bool(l == r)),
|
||
BinOpKind::Ne => Some(Constant::Bool(l != r)),
|
||
BinOpKind::Lt => Some(Constant::Bool(l < r)),
|
||
BinOpKind::Le => Some(Constant::Bool(l <= r)),
|
||
BinOpKind::Ge => Some(Constant::Bool(l >= r)),
|
||
BinOpKind::Gt => Some(Constant::Bool(l > r)),
|
||
_ => None,
|
||
},
|
||
_ => None,
|
||
},
|
||
(Constant::F32(l), Some(Constant::F32(r))) => match op.node {
|
||
BinOpKind::Add => Some(Constant::F32(l + r)),
|
||
BinOpKind::Sub => Some(Constant::F32(l - r)),
|
||
BinOpKind::Mul => Some(Constant::F32(l * r)),
|
||
BinOpKind::Div => Some(Constant::F32(l / r)),
|
||
BinOpKind::Rem => Some(Constant::F32(l % r)),
|
||
BinOpKind::Eq => Some(Constant::Bool(l == r)),
|
||
BinOpKind::Ne => Some(Constant::Bool(l != r)),
|
||
BinOpKind::Lt => Some(Constant::Bool(l < r)),
|
||
BinOpKind::Le => Some(Constant::Bool(l <= r)),
|
||
BinOpKind::Ge => Some(Constant::Bool(l >= r)),
|
||
BinOpKind::Gt => Some(Constant::Bool(l > r)),
|
||
_ => None,
|
||
},
|
||
(Constant::F64(l), Some(Constant::F64(r))) => match op.node {
|
||
BinOpKind::Add => Some(Constant::F64(l + r)),
|
||
BinOpKind::Sub => Some(Constant::F64(l - r)),
|
||
BinOpKind::Mul => Some(Constant::F64(l * r)),
|
||
BinOpKind::Div => Some(Constant::F64(l / r)),
|
||
BinOpKind::Rem => Some(Constant::F64(l % r)),
|
||
BinOpKind::Eq => Some(Constant::Bool(l == r)),
|
||
BinOpKind::Ne => Some(Constant::Bool(l != r)),
|
||
BinOpKind::Lt => Some(Constant::Bool(l < r)),
|
||
BinOpKind::Le => Some(Constant::Bool(l <= r)),
|
||
BinOpKind::Ge => Some(Constant::Bool(l >= r)),
|
||
BinOpKind::Gt => Some(Constant::Bool(l > r)),
|
||
_ => None,
|
||
},
|
||
(l, r) => match (op.node, l, r) {
|
||
(BinOpKind::And, Constant::Bool(false), _) => Some(Constant::Bool(false)),
|
||
(BinOpKind::Or, Constant::Bool(true), _) => Some(Constant::Bool(true)),
|
||
(BinOpKind::And, Constant::Bool(true), Some(r)) | (BinOpKind::Or, Constant::Bool(false), Some(r)) => {
|
||
Some(r)
|
||
},
|
||
(BinOpKind::BitXor, Constant::Bool(l), Some(Constant::Bool(r))) => Some(Constant::Bool(l ^ r)),
|
||
(BinOpKind::BitAnd, Constant::Bool(l), Some(Constant::Bool(r))) => Some(Constant::Bool(l & r)),
|
||
(BinOpKind::BitOr, Constant::Bool(l), Some(Constant::Bool(r))) => Some(Constant::Bool(l | r)),
|
||
_ => None,
|
||
},
|
||
}
|
||
}
|
||
}
|
||
|
||
pub fn miri_to_const(result: &ty::Const<'_>) -> Option<Constant> {
|
||
use rustc::mir::interpret::{ConstValue, Scalar};
|
||
match result.val {
|
||
ty::ConstKind::Value(ConstValue::Scalar(Scalar::Raw { data: d, .. })) => match result.ty.kind {
|
||
ty::Bool => Some(Constant::Bool(d == 1)),
|
||
ty::Uint(_) | ty::Int(_) => Some(Constant::Int(d)),
|
||
ty::Float(FloatTy::F32) => Some(Constant::F32(f32::from_bits(
|
||
d.try_into().expect("invalid f32 bit representation"),
|
||
))),
|
||
ty::Float(FloatTy::F64) => Some(Constant::F64(f64::from_bits(
|
||
d.try_into().expect("invalid f64 bit representation"),
|
||
))),
|
||
ty::RawPtr(type_and_mut) => {
|
||
if let ty::Uint(_) = type_and_mut.ty.kind {
|
||
return Some(Constant::RawPtr(d));
|
||
}
|
||
None
|
||
},
|
||
// FIXME: implement other conversions.
|
||
_ => None,
|
||
},
|
||
ty::ConstKind::Value(ConstValue::Slice { data, start, end }) => match result.ty.kind {
|
||
ty::Ref(_, tam, _) => match tam.kind {
|
||
ty::Str => String::from_utf8(
|
||
data.inspect_with_undef_and_ptr_outside_interpreter(start..end)
|
||
.to_owned(),
|
||
)
|
||
.ok()
|
||
.map(Constant::Str),
|
||
_ => None,
|
||
},
|
||
_ => None,
|
||
},
|
||
// FIXME: implement other conversions.
|
||
_ => None,
|
||
}
|
||
}
|