| // Copyright 2016 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 eval; |
| |
| use rustc::middle::const_val::{ConstEvalErr, ConstVal}; |
| use rustc::mir::{Field, BorrowKind, Mutability}; |
| use rustc::ty::{self, TyCtxt, AdtDef, Ty, Region}; |
| use rustc::ty::subst::{Substs, Kind}; |
| use rustc::hir::{self, PatKind, RangeEnd}; |
| use rustc::hir::def::{Def, CtorKind}; |
| use rustc::hir::pat_util::EnumerateAndAdjustIterator; |
| |
| use rustc_data_structures::indexed_vec::Idx; |
| |
| use std::fmt; |
| use syntax::ast; |
| use syntax::ptr::P; |
| use syntax_pos::Span; |
| |
| #[derive(Clone, Debug)] |
| pub enum PatternError<'tcx> { |
| StaticInPattern(Span), |
| ConstEval(ConstEvalErr<'tcx>), |
| } |
| |
| #[derive(Copy, Clone, Debug)] |
| pub enum BindingMode<'tcx> { |
| ByValue, |
| ByRef(Region<'tcx>, BorrowKind), |
| } |
| |
| #[derive(Clone, Debug)] |
| pub struct FieldPattern<'tcx> { |
| pub field: Field, |
| pub pattern: Pattern<'tcx>, |
| } |
| |
| #[derive(Clone, Debug)] |
| pub struct Pattern<'tcx> { |
| pub ty: Ty<'tcx>, |
| pub span: Span, |
| pub kind: Box<PatternKind<'tcx>>, |
| } |
| |
| #[derive(Clone, Debug)] |
| pub enum PatternKind<'tcx> { |
| Wild, |
| |
| /// x, ref x, x @ P, etc |
| Binding { |
| mutability: Mutability, |
| name: ast::Name, |
| mode: BindingMode<'tcx>, |
| var: ast::NodeId, |
| ty: Ty<'tcx>, |
| subpattern: Option<Pattern<'tcx>>, |
| }, |
| |
| /// Foo(...) or Foo{...} or Foo, where `Foo` is a variant name from an adt with >1 variants |
| Variant { |
| adt_def: &'tcx AdtDef, |
| substs: &'tcx Substs<'tcx>, |
| variant_index: usize, |
| subpatterns: Vec<FieldPattern<'tcx>>, |
| }, |
| |
| /// (...), Foo(...), Foo{...}, or Foo, where `Foo` is a variant name from an adt with 1 variant |
| Leaf { |
| subpatterns: Vec<FieldPattern<'tcx>>, |
| }, |
| |
| /// box P, &P, &mut P, etc |
| Deref { |
| subpattern: Pattern<'tcx>, |
| }, |
| |
| Constant { |
| value: &'tcx ty::Const<'tcx>, |
| }, |
| |
| Range { |
| lo: &'tcx ty::Const<'tcx>, |
| hi: &'tcx ty::Const<'tcx>, |
| end: RangeEnd, |
| }, |
| |
| /// matches against a slice, checking the length and extracting elements |
| Slice { |
| prefix: Vec<Pattern<'tcx>>, |
| slice: Option<Pattern<'tcx>>, |
| suffix: Vec<Pattern<'tcx>>, |
| }, |
| |
| /// fixed match against an array, irrefutable |
| Array { |
| prefix: Vec<Pattern<'tcx>>, |
| slice: Option<Pattern<'tcx>>, |
| suffix: Vec<Pattern<'tcx>>, |
| }, |
| } |
| |
| fn print_const_val(value: &ConstVal, f: &mut fmt::Formatter) -> fmt::Result { |
| match *value { |
| ConstVal::Float(ref x) => write!(f, "{}", x), |
| ConstVal::Integral(ref i) => write!(f, "{}", i), |
| ConstVal::Str(ref s) => write!(f, "{:?}", &s[..]), |
| ConstVal::ByteStr(b) => write!(f, "{:?}", b.data), |
| ConstVal::Bool(b) => write!(f, "{:?}", b), |
| ConstVal::Char(c) => write!(f, "{:?}", c), |
| ConstVal::Variant(_) | |
| ConstVal::Function(..) | |
| ConstVal::Aggregate(_) | |
| ConstVal::Unevaluated(..) => bug!("{:?} not printable in a pattern", value) |
| } |
| } |
| |
| impl<'tcx> fmt::Display for Pattern<'tcx> { |
| fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| match *self.kind { |
| PatternKind::Wild => write!(f, "_"), |
| PatternKind::Binding { mutability, name, mode, ref subpattern, .. } => { |
| let is_mut = match mode { |
| BindingMode::ByValue => mutability == Mutability::Mut, |
| BindingMode::ByRef(_, bk) => { |
| write!(f, "ref ")?; |
| bk == BorrowKind::Mut |
| } |
| }; |
| if is_mut { |
| write!(f, "mut ")?; |
| } |
| write!(f, "{}", name)?; |
| if let Some(ref subpattern) = *subpattern { |
| write!(f, " @ {}", subpattern)?; |
| } |
| Ok(()) |
| } |
| PatternKind::Variant { ref subpatterns, .. } | |
| PatternKind::Leaf { ref subpatterns } => { |
| let variant = match *self.kind { |
| PatternKind::Variant { adt_def, variant_index, .. } => { |
| Some(&adt_def.variants[variant_index]) |
| } |
| _ => if let ty::TyAdt(adt, _) = self.ty.sty { |
| if !adt.is_enum() { |
| Some(&adt.variants[0]) |
| } else { |
| None |
| } |
| } else { |
| None |
| } |
| }; |
| |
| let mut first = true; |
| let mut start_or_continue = || if first { first = false; "" } else { ", " }; |
| |
| if let Some(variant) = variant { |
| write!(f, "{}", variant.name)?; |
| |
| // Only for TyAdt we can have `S {...}`, |
| // which we handle separately here. |
| if variant.ctor_kind == CtorKind::Fictive { |
| write!(f, " {{ ")?; |
| |
| let mut printed = 0; |
| for p in subpatterns { |
| if let PatternKind::Wild = *p.pattern.kind { |
| continue; |
| } |
| let name = variant.fields[p.field.index()].name; |
| write!(f, "{}{}: {}", start_or_continue(), name, p.pattern)?; |
| printed += 1; |
| } |
| |
| if printed < variant.fields.len() { |
| write!(f, "{}..", start_or_continue())?; |
| } |
| |
| return write!(f, " }}"); |
| } |
| } |
| |
| let num_fields = variant.map_or(subpatterns.len(), |v| v.fields.len()); |
| if num_fields != 0 || variant.is_none() { |
| write!(f, "(")?; |
| for i in 0..num_fields { |
| write!(f, "{}", start_or_continue())?; |
| |
| // Common case: the field is where we expect it. |
| if let Some(p) = subpatterns.get(i) { |
| if p.field.index() == i { |
| write!(f, "{}", p.pattern)?; |
| continue; |
| } |
| } |
| |
| // Otherwise, we have to go looking for it. |
| if let Some(p) = subpatterns.iter().find(|p| p.field.index() == i) { |
| write!(f, "{}", p.pattern)?; |
| } else { |
| write!(f, "_")?; |
| } |
| } |
| write!(f, ")")?; |
| } |
| |
| Ok(()) |
| } |
| PatternKind::Deref { ref subpattern } => { |
| match self.ty.sty { |
| ty::TyAdt(def, _) if def.is_box() => write!(f, "box ")?, |
| ty::TyRef(_, mt) => { |
| write!(f, "&")?; |
| if mt.mutbl == hir::MutMutable { |
| write!(f, "mut ")?; |
| } |
| } |
| _ => bug!("{} is a bad Deref pattern type", self.ty) |
| } |
| write!(f, "{}", subpattern) |
| } |
| PatternKind::Constant { value } => { |
| print_const_val(&value.val, f) |
| } |
| PatternKind::Range { lo, hi, end } => { |
| print_const_val(&lo.val, f)?; |
| match end { |
| RangeEnd::Included => write!(f, "...")?, |
| RangeEnd::Excluded => write!(f, "..")?, |
| } |
| print_const_val(&hi.val, f) |
| } |
| PatternKind::Slice { ref prefix, ref slice, ref suffix } | |
| PatternKind::Array { ref prefix, ref slice, ref suffix } => { |
| let mut first = true; |
| let mut start_or_continue = || if first { first = false; "" } else { ", " }; |
| write!(f, "[")?; |
| for p in prefix { |
| write!(f, "{}{}", start_or_continue(), p)?; |
| } |
| if let Some(ref slice) = *slice { |
| write!(f, "{}", start_or_continue())?; |
| match *slice.kind { |
| PatternKind::Wild => {} |
| _ => write!(f, "{}", slice)? |
| } |
| write!(f, "..")?; |
| } |
| for p in suffix { |
| write!(f, "{}{}", start_or_continue(), p)?; |
| } |
| write!(f, "]") |
| } |
| } |
| } |
| } |
| |
| pub struct PatternContext<'a, 'tcx: 'a> { |
| pub tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| pub param_env: ty::ParamEnv<'tcx>, |
| pub tables: &'a ty::TypeckTables<'tcx>, |
| pub substs: &'tcx Substs<'tcx>, |
| pub errors: Vec<PatternError<'tcx>>, |
| } |
| |
| impl<'a, 'tcx> Pattern<'tcx> { |
| pub fn from_hir(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| param_env_and_substs: ty::ParamEnvAnd<'tcx, &'tcx Substs<'tcx>>, |
| tables: &'a ty::TypeckTables<'tcx>, |
| pat: &'tcx hir::Pat) -> Self { |
| let mut pcx = PatternContext::new(tcx, param_env_and_substs, tables); |
| let result = pcx.lower_pattern(pat); |
| if !pcx.errors.is_empty() { |
| span_bug!(pat.span, "encountered errors lowering pattern: {:?}", pcx.errors) |
| } |
| debug!("Pattern::from_hir({:?}) = {:?}", pat, result); |
| result |
| } |
| } |
| |
| impl<'a, 'tcx> PatternContext<'a, 'tcx> { |
| pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| param_env_and_substs: ty::ParamEnvAnd<'tcx, &'tcx Substs<'tcx>>, |
| tables: &'a ty::TypeckTables<'tcx>) -> Self { |
| PatternContext { |
| tcx, |
| param_env: param_env_and_substs.param_env, |
| tables, |
| substs: param_env_and_substs.value, |
| errors: vec![] |
| } |
| } |
| |
| pub fn lower_pattern(&mut self, pat: &'tcx hir::Pat) -> Pattern<'tcx> { |
| // When implicit dereferences have been inserted in this pattern, the unadjusted lowered |
| // pattern has the type that results *after* dereferencing. For example, in this code: |
| // |
| // ``` |
| // match &&Some(0i32) { |
| // Some(n) => { ... }, |
| // _ => { ... }, |
| // } |
| // ``` |
| // |
| // the type assigned to `Some(n)` in `unadjusted_pat` would be `Option<i32>` (this is |
| // determined in rustc_typeck::check::match). The adjustments would be |
| // |
| // `vec![&&Option<i32>, &Option<i32>]`. |
| // |
| // Applying the adjustments, we want to instead output `&&Some(n)` (as a HAIR pattern). So |
| // we wrap the unadjusted pattern in `PatternKind::Deref` repeatedly, consuming the |
| // adjustments in *reverse order* (last-in-first-out, so that the last `Deref` inserted |
| // gets the least-dereferenced type). |
| let unadjusted_pat = self.lower_pattern_unadjusted(pat); |
| self.tables |
| .pat_adjustments() |
| .get(pat.hir_id) |
| .unwrap_or(&vec![]) |
| .iter() |
| .rev() |
| .fold(unadjusted_pat, |pat, ref_ty| { |
| debug!("{:?}: wrapping pattern with type {:?}", pat, ref_ty); |
| Pattern { |
| span: pat.span, |
| ty: ref_ty, |
| kind: Box::new(PatternKind::Deref { subpattern: pat }), |
| } |
| }, |
| ) |
| } |
| |
| fn lower_pattern_unadjusted(&mut self, pat: &'tcx hir::Pat) -> Pattern<'tcx> { |
| let mut ty = self.tables.node_id_to_type(pat.hir_id); |
| |
| let kind = match pat.node { |
| PatKind::Wild => PatternKind::Wild, |
| |
| PatKind::Lit(ref value) => self.lower_lit(value), |
| |
| PatKind::Range(ref lo, ref hi, end) => { |
| match (self.lower_lit(lo), self.lower_lit(hi)) { |
| (PatternKind::Constant { value: lo }, |
| PatternKind::Constant { value: hi }) => { |
| PatternKind::Range { lo, hi, end } |
| } |
| _ => PatternKind::Wild |
| } |
| } |
| |
| PatKind::Path(ref qpath) => { |
| return self.lower_path(qpath, pat.hir_id, pat.id, pat.span); |
| } |
| |
| PatKind::Ref(ref subpattern, _) | |
| PatKind::Box(ref subpattern) => { |
| PatternKind::Deref { subpattern: self.lower_pattern(subpattern) } |
| } |
| |
| PatKind::Slice(ref prefix, ref slice, ref suffix) => { |
| let ty = self.tables.node_id_to_type(pat.hir_id); |
| match ty.sty { |
| ty::TyRef(_, mt) => |
| PatternKind::Deref { |
| subpattern: Pattern { |
| ty: mt.ty, |
| span: pat.span, |
| kind: Box::new(self.slice_or_array_pattern( |
| pat.span, mt.ty, prefix, slice, suffix)) |
| }, |
| }, |
| |
| ty::TySlice(..) | |
| ty::TyArray(..) => |
| self.slice_or_array_pattern(pat.span, ty, prefix, slice, suffix), |
| |
| ref sty => |
| span_bug!( |
| pat.span, |
| "unexpanded type for vector pattern: {:?}", |
| sty), |
| } |
| } |
| |
| PatKind::Tuple(ref subpatterns, ddpos) => { |
| let ty = self.tables.node_id_to_type(pat.hir_id); |
| match ty.sty { |
| ty::TyTuple(ref tys, _) => { |
| let subpatterns = |
| subpatterns.iter() |
| .enumerate_and_adjust(tys.len(), ddpos) |
| .map(|(i, subpattern)| FieldPattern { |
| field: Field::new(i), |
| pattern: self.lower_pattern(subpattern) |
| }) |
| .collect(); |
| |
| PatternKind::Leaf { subpatterns: subpatterns } |
| } |
| |
| ref sty => span_bug!(pat.span, "unexpected type for tuple pattern: {:?}", sty), |
| } |
| } |
| |
| PatKind::Binding(_, id, ref ident, ref sub) => { |
| let var_ty = self.tables.node_id_to_type(pat.hir_id); |
| let region = match var_ty.sty { |
| ty::TyRef(r, _) => Some(r), |
| _ => None, |
| }; |
| let bm = *self.tables.pat_binding_modes().get(pat.hir_id) |
| .expect("missing binding mode"); |
| let (mutability, mode) = match bm { |
| ty::BindByValue(hir::MutMutable) => |
| (Mutability::Mut, BindingMode::ByValue), |
| ty::BindByValue(hir::MutImmutable) => |
| (Mutability::Not, BindingMode::ByValue), |
| ty::BindByReference(hir::MutMutable) => |
| (Mutability::Not, BindingMode::ByRef( |
| region.unwrap(), BorrowKind::Mut)), |
| ty::BindByReference(hir::MutImmutable) => |
| (Mutability::Not, BindingMode::ByRef( |
| region.unwrap(), BorrowKind::Shared)), |
| }; |
| |
| // A ref x pattern is the same node used for x, and as such it has |
| // x's type, which is &T, where we want T (the type being matched). |
| if let ty::BindByReference(_) = bm { |
| if let ty::TyRef(_, mt) = ty.sty { |
| ty = mt.ty; |
| } else { |
| bug!("`ref {}` has wrong type {}", ident.node, ty); |
| } |
| } |
| |
| PatternKind::Binding { |
| mutability, |
| mode, |
| name: ident.node, |
| var: id, |
| ty: var_ty, |
| subpattern: self.lower_opt_pattern(sub), |
| } |
| } |
| |
| PatKind::TupleStruct(ref qpath, ref subpatterns, ddpos) => { |
| let def = self.tables.qpath_def(qpath, pat.hir_id); |
| let adt_def = match ty.sty { |
| ty::TyAdt(adt_def, _) => adt_def, |
| _ => span_bug!(pat.span, "tuple struct pattern not applied to an ADT"), |
| }; |
| let variant_def = adt_def.variant_of_def(def); |
| |
| let subpatterns = |
| subpatterns.iter() |
| .enumerate_and_adjust(variant_def.fields.len(), ddpos) |
| .map(|(i, field)| FieldPattern { |
| field: Field::new(i), |
| pattern: self.lower_pattern(field), |
| }) |
| .collect(); |
| self.lower_variant_or_leaf(def, ty, subpatterns) |
| } |
| |
| PatKind::Struct(ref qpath, ref fields, _) => { |
| let def = self.tables.qpath_def(qpath, pat.hir_id); |
| let adt_def = match ty.sty { |
| ty::TyAdt(adt_def, _) => adt_def, |
| _ => { |
| span_bug!( |
| pat.span, |
| "struct pattern not applied to an ADT"); |
| } |
| }; |
| let variant_def = adt_def.variant_of_def(def); |
| |
| let subpatterns = |
| fields.iter() |
| .map(|field| { |
| let index = variant_def.index_of_field_named(field.node.name); |
| let index = index.unwrap_or_else(|| { |
| span_bug!( |
| pat.span, |
| "no field with name {:?}", |
| field.node.name); |
| }); |
| FieldPattern { |
| field: Field::new(index), |
| pattern: self.lower_pattern(&field.node.pat), |
| } |
| }) |
| .collect(); |
| |
| self.lower_variant_or_leaf(def, ty, subpatterns) |
| } |
| }; |
| |
| Pattern { |
| span: pat.span, |
| ty, |
| kind: Box::new(kind), |
| } |
| } |
| |
| fn lower_patterns(&mut self, pats: &'tcx [P<hir::Pat>]) -> Vec<Pattern<'tcx>> { |
| pats.iter().map(|p| self.lower_pattern(p)).collect() |
| } |
| |
| fn lower_opt_pattern(&mut self, pat: &'tcx Option<P<hir::Pat>>) -> Option<Pattern<'tcx>> |
| { |
| pat.as_ref().map(|p| self.lower_pattern(p)) |
| } |
| |
| fn flatten_nested_slice_patterns( |
| &mut self, |
| prefix: Vec<Pattern<'tcx>>, |
| slice: Option<Pattern<'tcx>>, |
| suffix: Vec<Pattern<'tcx>>) |
| -> (Vec<Pattern<'tcx>>, Option<Pattern<'tcx>>, Vec<Pattern<'tcx>>) |
| { |
| let orig_slice = match slice { |
| Some(orig_slice) => orig_slice, |
| None => return (prefix, slice, suffix) |
| }; |
| let orig_prefix = prefix; |
| let orig_suffix = suffix; |
| |
| // dance because of intentional borrow-checker stupidity. |
| let kind = *orig_slice.kind; |
| match kind { |
| PatternKind::Slice { prefix, slice, mut suffix } | |
| PatternKind::Array { prefix, slice, mut suffix } => { |
| let mut orig_prefix = orig_prefix; |
| |
| orig_prefix.extend(prefix); |
| suffix.extend(orig_suffix); |
| |
| (orig_prefix, slice, suffix) |
| } |
| _ => { |
| (orig_prefix, Some(Pattern { |
| kind: box kind, ..orig_slice |
| }), orig_suffix) |
| } |
| } |
| } |
| |
| fn slice_or_array_pattern( |
| &mut self, |
| span: Span, |
| ty: Ty<'tcx>, |
| prefix: &'tcx [P<hir::Pat>], |
| slice: &'tcx Option<P<hir::Pat>>, |
| suffix: &'tcx [P<hir::Pat>]) |
| -> PatternKind<'tcx> |
| { |
| let prefix = self.lower_patterns(prefix); |
| let slice = self.lower_opt_pattern(slice); |
| let suffix = self.lower_patterns(suffix); |
| let (prefix, slice, suffix) = |
| self.flatten_nested_slice_patterns(prefix, slice, suffix); |
| |
| match ty.sty { |
| ty::TySlice(..) => { |
| // matching a slice or fixed-length array |
| PatternKind::Slice { prefix: prefix, slice: slice, suffix: suffix } |
| } |
| |
| ty::TyArray(_, len) => { |
| // fixed-length array |
| let len = len.val.to_const_int().unwrap().to_u64().unwrap(); |
| assert!(len >= prefix.len() as u64 + suffix.len() as u64); |
| PatternKind::Array { prefix: prefix, slice: slice, suffix: suffix } |
| } |
| |
| _ => { |
| span_bug!(span, "bad slice pattern type {:?}", ty); |
| } |
| } |
| } |
| |
| fn lower_variant_or_leaf( |
| &mut self, |
| def: Def, |
| ty: Ty<'tcx>, |
| subpatterns: Vec<FieldPattern<'tcx>>) |
| -> PatternKind<'tcx> |
| { |
| match def { |
| Def::Variant(variant_id) | Def::VariantCtor(variant_id, ..) => { |
| let enum_id = self.tcx.parent_def_id(variant_id).unwrap(); |
| let adt_def = self.tcx.adt_def(enum_id); |
| if adt_def.is_enum() { |
| let substs = match ty.sty { |
| ty::TyAdt(_, substs) | |
| ty::TyFnDef(_, substs) => substs, |
| _ => bug!("inappropriate type for def: {:?}", ty.sty), |
| }; |
| PatternKind::Variant { |
| adt_def, |
| substs, |
| variant_index: adt_def.variant_index_with_id(variant_id), |
| subpatterns, |
| } |
| } else { |
| PatternKind::Leaf { subpatterns: subpatterns } |
| } |
| } |
| |
| Def::Struct(..) | Def::StructCtor(..) | Def::Union(..) | |
| Def::TyAlias(..) | Def::AssociatedTy(..) | Def::SelfTy(..) => { |
| PatternKind::Leaf { subpatterns: subpatterns } |
| } |
| |
| _ => bug!() |
| } |
| } |
| |
| fn lower_path(&mut self, |
| qpath: &hir::QPath, |
| id: hir::HirId, |
| pat_id: ast::NodeId, |
| span: Span) |
| -> Pattern<'tcx> { |
| let ty = self.tables.node_id_to_type(id); |
| let def = self.tables.qpath_def(qpath, id); |
| let kind = match def { |
| Def::Const(def_id) | Def::AssociatedConst(def_id) => { |
| let substs = self.tables.node_substs(id); |
| match eval::lookup_const_by_id(self.tcx, self.param_env.and((def_id, substs))) { |
| Some((def_id, substs)) => { |
| // Enter the inlined constant's tables&substs temporarily. |
| let old_tables = self.tables; |
| let old_substs = self.substs; |
| self.tables = self.tcx.typeck_tables_of(def_id); |
| self.substs = substs; |
| let body = if let Some(id) = self.tcx.hir.as_local_node_id(def_id) { |
| self.tcx.hir.body(self.tcx.hir.body_owned_by(id)) |
| } else { |
| self.tcx.extern_const_body(def_id).body |
| }; |
| let pat = self.lower_const_expr(&body.value, pat_id, span); |
| self.tables = old_tables; |
| self.substs = old_substs; |
| return pat; |
| } |
| None => { |
| self.errors.push(PatternError::StaticInPattern(span)); |
| PatternKind::Wild |
| } |
| } |
| } |
| _ => self.lower_variant_or_leaf(def, ty, vec![]), |
| }; |
| |
| Pattern { |
| span, |
| ty, |
| kind: Box::new(kind), |
| } |
| } |
| |
| fn lower_lit(&mut self, expr: &'tcx hir::Expr) -> PatternKind<'tcx> { |
| let const_cx = eval::ConstContext::new(self.tcx, |
| self.param_env.and(self.substs), |
| self.tables); |
| match const_cx.eval(expr) { |
| Ok(value) => { |
| if let ConstVal::Variant(def_id) = value.val { |
| let ty = self.tables.expr_ty(expr); |
| self.lower_variant_or_leaf(Def::Variant(def_id), ty, vec![]) |
| } else { |
| PatternKind::Constant { value } |
| } |
| } |
| Err(e) => { |
| self.errors.push(PatternError::ConstEval(e)); |
| PatternKind::Wild |
| } |
| } |
| } |
| |
| fn lower_const_expr(&mut self, |
| expr: &'tcx hir::Expr, |
| pat_id: ast::NodeId, |
| span: Span) |
| -> Pattern<'tcx> { |
| let pat_ty = self.tables.expr_ty(expr); |
| debug!("expr={:?} pat_ty={:?} pat_id={}", expr, pat_ty, pat_id); |
| match pat_ty.sty { |
| ty::TyFloat(_) => { |
| self.tcx.sess.span_err(span, "floating point constants cannot be used in patterns"); |
| } |
| ty::TyAdt(adt_def, _) if adt_def.is_union() => { |
| // Matching on union fields is unsafe, we can't hide it in constants |
| self.tcx.sess.span_err(span, "cannot use unions in constant patterns"); |
| } |
| ty::TyAdt(adt_def, _) => { |
| if !self.tcx.has_attr(adt_def.did, "structural_match") { |
| let msg = format!("to use a constant of type `{}` in a pattern, \ |
| `{}` must be annotated with `#[derive(PartialEq, Eq)]`", |
| self.tcx.item_path_str(adt_def.did), |
| self.tcx.item_path_str(adt_def.did)); |
| self.tcx.sess.span_err(span, &msg); |
| } |
| } |
| _ => { } |
| } |
| let kind = match expr.node { |
| hir::ExprTup(ref exprs) => { |
| PatternKind::Leaf { |
| subpatterns: exprs.iter().enumerate().map(|(i, expr)| { |
| FieldPattern { |
| field: Field::new(i), |
| pattern: self.lower_const_expr(expr, pat_id, span) |
| } |
| }).collect() |
| } |
| } |
| |
| hir::ExprCall(ref callee, ref args) => { |
| let qpath = match callee.node { |
| hir::ExprPath(ref qpath) => qpath, |
| _ => bug!() |
| }; |
| let ty = self.tables.node_id_to_type(callee.hir_id); |
| let def = self.tables.qpath_def(qpath, callee.hir_id); |
| match def { |
| Def::Fn(..) | Def::Method(..) => self.lower_lit(expr), |
| _ => { |
| let subpatterns = args.iter().enumerate().map(|(i, expr)| { |
| FieldPattern { |
| field: Field::new(i), |
| pattern: self.lower_const_expr(expr, pat_id, span) |
| } |
| }).collect(); |
| self.lower_variant_or_leaf(def, ty, subpatterns) |
| } |
| } |
| } |
| |
| hir::ExprStruct(ref qpath, ref fields, None) => { |
| let def = self.tables.qpath_def(qpath, expr.hir_id); |
| let adt_def = match pat_ty.sty { |
| ty::TyAdt(adt_def, _) => adt_def, |
| _ => { |
| span_bug!( |
| expr.span, |
| "struct expr without ADT type"); |
| } |
| }; |
| let variant_def = adt_def.variant_of_def(def); |
| |
| let subpatterns = |
| fields.iter() |
| .map(|field| { |
| let index = variant_def.index_of_field_named(field.name.node); |
| let index = index.unwrap_or_else(|| { |
| span_bug!( |
| expr.span, |
| "no field with name {:?}", |
| field.name); |
| }); |
| FieldPattern { |
| field: Field::new(index), |
| pattern: self.lower_const_expr(&field.expr, pat_id, span), |
| } |
| }) |
| .collect(); |
| |
| self.lower_variant_or_leaf(def, pat_ty, subpatterns) |
| } |
| |
| hir::ExprArray(ref exprs) => { |
| let pats = exprs.iter() |
| .map(|expr| self.lower_const_expr(expr, pat_id, span)) |
| .collect(); |
| PatternKind::Array { |
| prefix: pats, |
| slice: None, |
| suffix: vec![] |
| } |
| } |
| |
| hir::ExprPath(ref qpath) => { |
| return self.lower_path(qpath, expr.hir_id, pat_id, span); |
| } |
| |
| _ => self.lower_lit(expr) |
| }; |
| |
| Pattern { |
| span, |
| ty: pat_ty, |
| kind: Box::new(kind), |
| } |
| } |
| } |
| |
| pub trait PatternFoldable<'tcx> : Sized { |
| fn fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self { |
| self.super_fold_with(folder) |
| } |
| |
| fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self; |
| } |
| |
| pub trait PatternFolder<'tcx> : Sized { |
| fn fold_pattern(&mut self, pattern: &Pattern<'tcx>) -> Pattern<'tcx> { |
| pattern.super_fold_with(self) |
| } |
| |
| fn fold_pattern_kind(&mut self, kind: &PatternKind<'tcx>) -> PatternKind<'tcx> { |
| kind.super_fold_with(self) |
| } |
| } |
| |
| |
| impl<'tcx, T: PatternFoldable<'tcx>> PatternFoldable<'tcx> for Box<T> { |
| fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self { |
| let content: T = (**self).fold_with(folder); |
| box content |
| } |
| } |
| |
| impl<'tcx, T: PatternFoldable<'tcx>> PatternFoldable<'tcx> for Vec<T> { |
| fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self { |
| self.iter().map(|t| t.fold_with(folder)).collect() |
| } |
| } |
| |
| impl<'tcx, T: PatternFoldable<'tcx>> PatternFoldable<'tcx> for Option<T> { |
| fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self{ |
| self.as_ref().map(|t| t.fold_with(folder)) |
| } |
| } |
| |
| macro_rules! CloneImpls { |
| (<$lt_tcx:tt> $($ty:ty),+) => { |
| $( |
| impl<$lt_tcx> PatternFoldable<$lt_tcx> for $ty { |
| fn super_fold_with<F: PatternFolder<$lt_tcx>>(&self, _: &mut F) -> Self { |
| Clone::clone(self) |
| } |
| } |
| )+ |
| } |
| } |
| |
| CloneImpls!{ <'tcx> |
| Span, Field, Mutability, ast::Name, ast::NodeId, usize, &'tcx ty::Const<'tcx>, |
| Region<'tcx>, Ty<'tcx>, BindingMode<'tcx>, &'tcx AdtDef, |
| &'tcx Substs<'tcx>, &'tcx Kind<'tcx> |
| } |
| |
| impl<'tcx> PatternFoldable<'tcx> for FieldPattern<'tcx> { |
| fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self { |
| FieldPattern { |
| field: self.field.fold_with(folder), |
| pattern: self.pattern.fold_with(folder) |
| } |
| } |
| } |
| |
| impl<'tcx> PatternFoldable<'tcx> for Pattern<'tcx> { |
| fn fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self { |
| folder.fold_pattern(self) |
| } |
| |
| fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self { |
| Pattern { |
| ty: self.ty.fold_with(folder), |
| span: self.span.fold_with(folder), |
| kind: self.kind.fold_with(folder) |
| } |
| } |
| } |
| |
| impl<'tcx> PatternFoldable<'tcx> for PatternKind<'tcx> { |
| fn fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self { |
| folder.fold_pattern_kind(self) |
| } |
| |
| fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self { |
| match *self { |
| PatternKind::Wild => PatternKind::Wild, |
| PatternKind::Binding { |
| mutability, |
| name, |
| mode, |
| var, |
| ty, |
| ref subpattern, |
| } => PatternKind::Binding { |
| mutability: mutability.fold_with(folder), |
| name: name.fold_with(folder), |
| mode: mode.fold_with(folder), |
| var: var.fold_with(folder), |
| ty: ty.fold_with(folder), |
| subpattern: subpattern.fold_with(folder), |
| }, |
| PatternKind::Variant { |
| adt_def, |
| substs, |
| variant_index, |
| ref subpatterns, |
| } => PatternKind::Variant { |
| adt_def: adt_def.fold_with(folder), |
| substs: substs.fold_with(folder), |
| variant_index: variant_index.fold_with(folder), |
| subpatterns: subpatterns.fold_with(folder) |
| }, |
| PatternKind::Leaf { |
| ref subpatterns, |
| } => PatternKind::Leaf { |
| subpatterns: subpatterns.fold_with(folder), |
| }, |
| PatternKind::Deref { |
| ref subpattern, |
| } => PatternKind::Deref { |
| subpattern: subpattern.fold_with(folder), |
| }, |
| PatternKind::Constant { |
| value |
| } => PatternKind::Constant { |
| value: value.fold_with(folder) |
| }, |
| PatternKind::Range { |
| lo, |
| hi, |
| end, |
| } => PatternKind::Range { |
| lo: lo.fold_with(folder), |
| hi: hi.fold_with(folder), |
| end, |
| }, |
| PatternKind::Slice { |
| ref prefix, |
| ref slice, |
| ref suffix, |
| } => PatternKind::Slice { |
| prefix: prefix.fold_with(folder), |
| slice: slice.fold_with(folder), |
| suffix: suffix.fold_with(folder) |
| }, |
| PatternKind::Array { |
| ref prefix, |
| ref slice, |
| ref suffix |
| } => PatternKind::Array { |
| prefix: prefix.fold_with(folder), |
| slice: slice.fold_with(folder), |
| suffix: suffix.fold_with(folder) |
| }, |
| } |
| } |
| } |
