/
pat_util.rs
216 lines (197 loc) · 7.41 KB
/
pat_util.rs
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// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use hir::def::Def;
use hir::def_id::DefId;
use hir::{self, HirId, PatKind};
use syntax::ast;
use syntax::codemap::Spanned;
use syntax_pos::Span;
use std::iter::{Enumerate, ExactSizeIterator};
pub struct EnumerateAndAdjust<I> {
enumerate: Enumerate<I>,
gap_pos: usize,
gap_len: usize,
}
impl<I> Iterator for EnumerateAndAdjust<I> where I: Iterator {
type Item = (usize, <I as Iterator>::Item);
fn next(&mut self) -> Option<(usize, <I as Iterator>::Item)> {
self.enumerate.next().map(|(i, elem)| {
(if i < self.gap_pos { i } else { i + self.gap_len }, elem)
})
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.enumerate.size_hint()
}
}
pub trait EnumerateAndAdjustIterator {
fn enumerate_and_adjust(self, expected_len: usize, gap_pos: Option<usize>)
-> EnumerateAndAdjust<Self> where Self: Sized;
}
impl<T: ExactSizeIterator> EnumerateAndAdjustIterator for T {
fn enumerate_and_adjust(self, expected_len: usize, gap_pos: Option<usize>)
-> EnumerateAndAdjust<Self> where Self: Sized {
let actual_len = self.len();
EnumerateAndAdjust {
enumerate: self.enumerate(),
gap_pos: if let Some(gap_pos) = gap_pos { gap_pos } else { expected_len },
gap_len: expected_len - actual_len,
}
}
}
impl hir::Pat {
pub fn is_refutable(&self) -> bool {
match self.node {
PatKind::Lit(_) |
PatKind::Range(..) |
PatKind::Path(hir::QPath::Resolved(Some(..), _)) |
PatKind::Path(hir::QPath::TypeRelative(..)) => true,
PatKind::Path(hir::QPath::Resolved(_, ref path)) |
PatKind::TupleStruct(hir::QPath::Resolved(_, ref path), ..) |
PatKind::Struct(hir::QPath::Resolved(_, ref path), ..) => {
match path.def {
Def::Variant(..) | Def::VariantCtor(..) => true,
_ => false
}
}
PatKind::Slice(..) => true,
_ => false
}
}
pub fn is_const(&self) -> bool {
match self.node {
PatKind::Path(hir::QPath::TypeRelative(..)) => true,
PatKind::Path(hir::QPath::Resolved(_, ref path)) => {
match path.def {
Def::Const(..) | Def::AssociatedConst(..) => true,
_ => false
}
}
_ => false
}
}
/// Call `f` on every "binding" in a pattern, e.g., on `a` in
/// `match foo() { Some(a) => (), None => () }`
pub fn each_binding<F>(&self, mut f: F)
where F: FnMut(hir::BindingAnnotation, HirId, Span, &Spanned<ast::Name>),
{
self.walk(|p| {
if let PatKind::Binding(binding_mode, _, ref pth, _) = p.node {
f(binding_mode, p.hir_id, p.span, pth);
}
true
});
}
/// Checks if the pattern contains any patterns that bind something to
/// an ident, e.g. `foo`, or `Foo(foo)` or `foo @ Bar(..)`.
pub fn contains_bindings(&self) -> bool {
let mut contains_bindings = false;
self.walk(|p| {
if let PatKind::Binding(..) = p.node {
contains_bindings = true;
false // there's at least one binding, can short circuit now.
} else {
true
}
});
contains_bindings
}
/// Checks if the pattern contains any patterns that bind something to
/// an ident or wildcard, e.g. `foo`, or `Foo(_)`, `foo @ Bar(..)`,
pub fn contains_bindings_or_wild(&self) -> bool {
let mut contains_bindings = false;
self.walk(|p| {
match p.node {
PatKind::Binding(..) | PatKind::Wild => {
contains_bindings = true;
false // there's at least one binding/wildcard, can short circuit now.
}
_ => true
}
});
contains_bindings
}
pub fn simple_name(&self) -> Option<ast::Name> {
match self.node {
PatKind::Binding(hir::BindingAnnotation::Unannotated, _, ref path1, None) |
PatKind::Binding(hir::BindingAnnotation::Mutable, _, ref path1, None) =>
Some(path1.node),
_ => None,
}
}
pub fn simple_span(&self) -> Option<Span> {
match self.node {
PatKind::Binding(hir::BindingAnnotation::Unannotated, _, ref path1, None) |
PatKind::Binding(hir::BindingAnnotation::Mutable, _, ref path1, None) =>
Some(path1.span),
_ => None,
}
}
/// Return variants that are necessary to exist for the pattern to match.
pub fn necessary_variants(&self) -> Vec<DefId> {
let mut variants = vec![];
self.walk(|p| {
match p.node {
PatKind::Path(hir::QPath::Resolved(_, ref path)) |
PatKind::TupleStruct(hir::QPath::Resolved(_, ref path), ..) |
PatKind::Struct(hir::QPath::Resolved(_, ref path), ..) => {
match path.def {
Def::Variant(id) |
Def::VariantCtor(id, ..) => variants.push(id),
_ => ()
}
}
_ => ()
}
true
});
variants.sort();
variants.dedup();
variants
}
/// Checks if the pattern contains any `ref` or `ref mut` bindings, and if
/// yes whether it contains mutable or just immutables ones.
///
/// FIXME(tschottdorf): this is problematic as the HIR is being scraped, but
/// ref bindings are be implicit after #42640 (default match binding modes).
///
/// See #44848.
pub fn contains_explicit_ref_binding(&self) -> Option<hir::Mutability> {
let mut result = None;
self.each_binding(|annotation, _, _, _| {
match annotation {
hir::BindingAnnotation::Ref => {
match result {
None | Some(hir::MutImmutable) => result = Some(hir::MutImmutable),
_ => (),
}
}
hir::BindingAnnotation::RefMut => result = Some(hir::MutMutable),
_ => (),
}
});
result
}
}
impl hir::Arm {
/// Checks if the patterns for this arm contain any `ref` or `ref mut`
/// bindings, and if yes whether its containing mutable ones or just immutables ones.
pub fn contains_explicit_ref_binding(&self) -> Option<hir::Mutability> {
// FIXME(tschottdorf): contains_explicit_ref_binding() must be removed
// for #42640 (default match binding modes).
//
// See #44848.
self.pats.iter()
.filter_map(|pat| pat.contains_explicit_ref_binding())
.max_by_key(|m| match *m {
hir::MutMutable => 1,
hir::MutImmutable => 0,
})
}
}