Replace pat_adjust_pos with an iterator adapter

Author: petrochenkov

src/librustc/hir/pat_util.rs

@@ -18,28 +18,40 @@ use hir::{self, PatKind};
 use syntax::codemap::{respan, Span, Spanned, DUMMY_SP};
 
 use std::cell::RefCell;
+use std::iter::{Enumerate, ExactSizeIterator};
 
 pub type PatIdMap = FnvHashMap<ast::Name, ast::NodeId>;
 
-#[derive(Clone, Copy)]
-pub struct AdjustPos {
+pub struct EnumerateAndAdjust<I> {
+    enumerate: Enumerate<I>,
     gap_pos: usize,
     gap_len: usize,
 }
 
-impl FnOnce<(usize,)> for AdjustPos {
-    type Output = usize;
-    extern "rust-call" fn call_once(self, (i,): (usize,)) -> usize {
-        if i < self.gap_pos { i } else { i + self.gap_len }
+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)
+        })
     }
 }
 
-// Returns a functional object used to adjust tuple pattern indexes. Example: for 5-tuple and
-// pattern (a, b, .., c) expected_len is 5, actual_len is 3 and gap_pos is Some(2).
-pub fn pat_adjust_pos(expected_len: usize, actual_len: usize, gap_pos: Option<usize>) -> AdjustPos {
-    AdjustPos {
-        gap_pos: if let Some(gap_pos) = gap_pos { gap_pos } else { expected_len },
-        gap_len: expected_len - actual_len,
+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,
+        }
     }
 }
 

src/librustc/lib.rs

@@ -29,7 +29,6 @@
 #![feature(collections)]
 #![feature(const_fn)]
 #![feature(enumset)]
-#![feature(fn_traits)]
 #![feature(iter_arith)]
 #![feature(libc)]
 #![feature(nonzero)]
@@ -39,7 +38,6 @@
 #![feature(slice_patterns)]
 #![feature(staged_api)]
 #![feature(question_mark)]
-#![feature(unboxed_closures)]
 #![cfg_attr(test, feature(test))]
 
 extern crate arena;

src/librustc/middle/mem_categorization.rs

@@ -80,7 +80,7 @@ use ty::adjustment;
 use ty::{self, Ty, TyCtxt};
 
 use hir::{MutImmutable, MutMutable, PatKind};
-use hir::pat_util::pat_adjust_pos;
+use hir::pat_util::EnumerateAndAdjustIterator;
 use hir;
 use syntax::ast;
 use syntax::codemap::Span;
@@ -1230,15 +1230,15 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
             match opt_def {
                 Some(Def::Variant(enum_def, def_id)) => {
                     // variant(x, y, z)
-                    let variant = self.tcx().lookup_adt_def(enum_def).variant_with_id(def_id);
-                    let adjust = pat_adjust_pos(variant.fields.len(), subpats.len(), ddpos);
-                    for (i, subpat) in subpats.iter().enumerate() {
+                    let expected_len = self.tcx().lookup_adt_def(enum_def)
+                                                 .variant_with_id(def_id).fields.len();
+                    for (i, subpat) in subpats.iter().enumerate_and_adjust(expected_len, ddpos) {
                         let subpat_ty = self.pat_ty(&subpat)?; // see (*2)
 
                         let subcmt =
                             self.cat_imm_interior(
                                 pat, cmt.clone(), subpat_ty,
-                                InteriorField(PositionalField(adjust(i))));
+                                InteriorField(PositionalField(i)));
 
                         self.cat_pattern_(subcmt, &subpat, op)?;
                     }
@@ -1253,13 +1253,12 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
                         }
                     };
 
-                    let adjust = pat_adjust_pos(expected_len, subpats.len(), ddpos);
-                    for (i, subpat) in subpats.iter().enumerate() {
+                    for (i, subpat) in subpats.iter().enumerate_and_adjust(expected_len, ddpos) {
                         let subpat_ty = self.pat_ty(&subpat)?; // see (*2)
                         let cmt_field =
                             self.cat_imm_interior(
                                 pat, cmt.clone(), subpat_ty,
-                                InteriorField(PositionalField(adjust(i))));
+                                InteriorField(PositionalField(i)));
                         self.cat_pattern_(cmt_field, &subpat, op)?;
                     }
                 }
@@ -1300,13 +1299,12 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
                 Ok(&ty::TyS{sty: ty::TyTuple(ref tys), ..}) => tys.len(),
                 ref ty => span_bug!(pat.span, "tuple pattern unexpected type {:?}", ty),
             };
-            let adjust = pat_adjust_pos(expected_len, subpats.len(), ddpos);
-            for (i, subpat) in subpats.iter().enumerate() {
+            for (i, subpat) in subpats.iter().enumerate_and_adjust(expected_len, ddpos) {
                 let subpat_ty = self.pat_ty(&subpat)?; // see (*2)
                 let subcmt =
                     self.cat_imm_interior(
                         pat, cmt.clone(), subpat_ty,
-                        InteriorField(PositionalField(adjust(i))));
+                        InteriorField(PositionalField(i)));
                 self.cat_pattern_(subcmt, &subpat, op)?;
             }
           }

src/librustc/middle/stability.rs

@@ -33,7 +33,7 @@ use util::nodemap::{DefIdMap, FnvHashSet, FnvHashMap};
 use hir;
 use hir::{Item, Generics, StructField, Variant, PatKind};
 use hir::intravisit::{self, Visitor};
-use hir::pat_util::pat_adjust_pos;
+use hir::pat_util::EnumerateAndAdjustIterator;
 
 use std::mem::replace;
 use std::cmp::Ordering;
@@ -616,9 +616,8 @@ pub fn check_pat<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, pat: &hir::Pat,
     match pat.node {
         // Foo(a, b, c)
         PatKind::TupleStruct(_, ref pat_fields, ddpos) => {
-            let adjust = pat_adjust_pos(v.fields.len(), pat_fields.len(), ddpos);
-            for (i, field) in pat_fields.iter().enumerate() {
-                maybe_do_stability_check(tcx, v.fields[adjust(i)].did, field.span, cb)
+            for (i, field) in pat_fields.iter().enumerate_and_adjust(v.fields.len(), ddpos) {
+                maybe_do_stability_check(tcx, v.fields[i].did, field.span, cb)
             }
         }
         // Foo { a, b, c }

src/librustc_const_eval/check_match.rs

@@ -924,7 +924,7 @@ pub fn specialize<'a>(cx: &MatchCheckCtxt, r: &[&'a Pat],
                 Def::Variant(..) | Def::Struct(..) => {
                     match ddpos {
                         Some(ddpos) => {
-                            let mut pats = args[..ddpos].iter().map(|p| &**p).collect(): Vec<_>;
+                            let mut pats: Vec<_> = args[..ddpos].iter().map(|p| &**p).collect();
                             pats.extend(repeat(DUMMY_WILD_PAT).take(arity - args.len()));
                             pats.extend(args[ddpos..].iter().map(|p| &**p));
                             Some(pats)
@@ -958,7 +958,7 @@ pub fn specialize<'a>(cx: &MatchCheckCtxt, r: &[&'a Pat],
         }
 
         PatKind::Tuple(ref args, Some(ddpos)) => {
-            let mut pats = args[..ddpos].iter().map(|p| &**p).collect(): Vec<_>;
+            let mut pats: Vec<_> = args[..ddpos].iter().map(|p| &**p).collect();
             pats.extend(repeat(DUMMY_WILD_PAT).take(arity - args.len()));
             pats.extend(args[ddpos..].iter().map(|p| &**p));
             Some(pats)

src/librustc_const_eval/lib.rs

@@ -31,7 +31,6 @@
 #![feature(question_mark)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
-#![feature(type_ascription)]
 
 #[macro_use] extern crate syntax;
 #[macro_use] extern crate log;

src/librustc_mir/hair/cx/pattern.rs

@@ -13,7 +13,7 @@ use hair::cx::Cx;
 use rustc_data_structures::fnv::FnvHashMap;
 use rustc_const_eval as const_eval;
 use rustc::hir::def::Def;
-use rustc::hir::pat_util::{pat_adjust_pos, pat_is_resolved_const, pat_is_binding};
+use rustc::hir::pat_util::{EnumerateAndAdjustIterator, pat_is_resolved_const, pat_is_binding};
 use rustc::ty::{self, Ty};
 use rustc::mir::repr::*;
 use rustc::hir::{self, PatKind};
@@ -151,12 +151,11 @@ impl<'patcx, 'cx, 'gcx, 'tcx> PatCx<'patcx, 'cx, 'gcx, 'tcx> {
             PatKind::Tuple(ref subpatterns, ddpos) => {
                 match self.cx.tcx.node_id_to_type(pat.id).sty {
                     ty::TyTuple(ref tys) => {
-                        let adjust = pat_adjust_pos(tys.len(), subpatterns.len(), ddpos);
                         let subpatterns =
                             subpatterns.iter()
-                                       .enumerate()
+                                       .enumerate_and_adjust(tys.len(), ddpos)
                                        .map(|(i, subpattern)| FieldPattern {
-                                            field: Field::new(adjust(i)),
+                                            field: Field::new(i),
                                             pattern: self.to_pattern(subpattern),
                                        })
                                        .collect();
@@ -224,12 +223,11 @@ impl<'patcx, 'cx, 'gcx, 'tcx> PatCx<'patcx, 'cx, 'gcx, 'tcx> {
                 let def = self.cx.tcx.def_map.borrow().get(&pat.id).unwrap().full_def();
                 let variant_def = adt_def.variant_of_def(def);
 
-                let adjust = pat_adjust_pos(variant_def.fields.len(), subpatterns.len(), ddpos);
                 let subpatterns =
                         subpatterns.iter()
-                                   .enumerate()
+                                   .enumerate_and_adjust(variant_def.fields.len(), ddpos)
                                    .map(|(i, field)| FieldPattern {
-                                       field: Field::new(adjust(i)),
+                                       field: Field::new(i),
                                        pattern: self.to_pattern(field),
                                    })
                                    .collect();

src/librustc_privacy/lib.rs

@@ -31,7 +31,7 @@ use std::mem::replace;
 
 use rustc::hir::{self, PatKind};
 use rustc::hir::intravisit::{self, Visitor};
-use rustc::hir::pat_util::pat_adjust_pos;
+use rustc::hir::pat_util::EnumerateAndAdjustIterator;
 use rustc::dep_graph::DepNode;
 use rustc::lint;
 use rustc::hir::def::{self, Def};
@@ -491,14 +491,12 @@ impl<'a, 'tcx, 'v> Visitor<'v> for PrivacyVisitor<'a, 'tcx> {
             PatKind::TupleStruct(_, ref fields, ddpos) => {
                 match self.tcx.pat_ty(pattern).sty {
                     ty::TyStruct(def, _) => {
-                        let adjust = pat_adjust_pos(def.struct_variant().fields.len(),
-                                                    fields.len(), ddpos);
-                        for (i, field) in fields.iter().enumerate() {
+                        let expected_len = def.struct_variant().fields.len();
+                        for (i, field) in fields.iter().enumerate_and_adjust(expected_len, ddpos) {
                             if let PatKind::Wild = field.node {
                                 continue
                             }
-                            self.check_field(field.span, def,
-                                             &def.struct_variant().fields[adjust(i)]);
+                            self.check_field(field.span, def, &def.struct_variant().fields[i]);
                         }
                     }
                     ty::TyEnum(..) => {

src/librustc_trans/_match.rs

@@ -1843,12 +1843,12 @@ pub fn bind_irrefutable_pat<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
                                                     &repr,
                                                     Disr::from(vinfo.disr_val),
                                                     val);
-                    let adjust = pat_adjust_pos(vinfo.fields.len(), sub_pats.len(), ddpos);
-                    for (i, subpat) in sub_pats.iter().enumerate() {
+                    for (i, subpat) in sub_pats.iter()
+                                               .enumerate_and_adjust(vinfo.fields.len(), ddpos) {
                         bcx = bind_irrefutable_pat(
                             bcx,
                             subpat,
-                            MatchInput::from_val(args.vals[adjust(i)]),
+                            MatchInput::from_val(args.vals[i]),
                             cleanup_scope);
                     }
                 }
@@ -1862,12 +1862,10 @@ pub fn bind_irrefutable_pat<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
                         }
                     };
 
-                    let adjust = pat_adjust_pos(expected_len, sub_pats.len(), ddpos);
                     let repr = adt::represent_node(bcx, pat.id);
                     let val = adt::MaybeSizedValue::sized(val.val);
-                    for (i, elem) in sub_pats.iter().enumerate() {
-                        let fldptr = adt::trans_field_ptr(bcx, &repr,
-                                                          val, Disr(0), adjust(i));
+                    for (i, elem) in sub_pats.iter().enumerate_and_adjust(expected_len, ddpos) {
+                        let fldptr = adt::trans_field_ptr(bcx, &repr, val, Disr(0), i);
                         bcx = bind_irrefutable_pat(
                             bcx,
                             &elem,
@@ -1923,11 +1921,10 @@ pub fn bind_irrefutable_pat<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
         PatKind::Tuple(ref elems, ddpos) => {
             match tcx.node_id_to_type(pat.id).sty {
                 ty::TyTuple(ref tys) => {
-                    let adjust = pat_adjust_pos(tys.len(), elems.len(), ddpos);
                     let repr = adt::represent_node(bcx, pat.id);
                     let val = adt::MaybeSizedValue::sized(val.val);
-                    for (i, elem) in elems.iter().enumerate() {
-                        let fldptr = adt::trans_field_ptr(bcx, &repr, val, Disr(0), adjust(i));
+                    for (i, elem) in elems.iter().enumerate_and_adjust(tys.len(), ddpos) {
+                        let fldptr = adt::trans_field_ptr(bcx, &repr, val, Disr(0), i);
                         bcx = bind_irrefutable_pat(
                             bcx,
                             &elem,

src/librustc_typeck/check/_match.rs

@@ -11,7 +11,7 @@
 use hir::def::{self, Def};
 use rustc::infer::{self, InferOk, TypeOrigin};
 use hir::pat_util::{PatIdMap, pat_id_map, pat_is_binding};
-use hir::pat_util::{pat_adjust_pos, pat_is_resolved_const};
+use hir::pat_util::{EnumerateAndAdjustIterator, pat_is_resolved_const};
 use rustc::ty::subst::Substs;
 use rustc::ty::{self, Ty, TypeFoldable, LvaluePreference};
 use check::{FnCtxt, Expectation};
@@ -271,13 +271,12 @@ impl<'a, 'gcx, 'tcx> PatCtxt<'a, 'gcx, 'tcx> {
                 }
                 let max_len = cmp::max(expected_len, elements.len());
 
-                let element_tys = (0 .. max_len).map(|_| self.next_ty_var()).collect(): Vec<_>;
+                let element_tys: Vec<_> = (0 .. max_len).map(|_| self.next_ty_var()).collect();
                 let pat_ty = tcx.mk_tup(element_tys.clone());
                 self.write_ty(pat.id, pat_ty);
                 self.demand_eqtype(pat.span, expected, pat_ty);
-                let adjust = pat_adjust_pos(expected_len, elements.len(), ddpos);
-                for i in 0 .. elements.len() {
-                    self.check_pat(&elements[i], &element_tys[adjust(i)]);
+                for (i, elem) in elements.iter().enumerate_and_adjust(expected_len, ddpos) {
+                    self.check_pat(elem, &element_tys[i]);
                 }
             }
             PatKind::Box(ref inner) => {
@@ -734,12 +733,10 @@ impl<'a, 'gcx, 'tcx> PatCtxt<'a, 'gcx, 'tcx> {
             _ => {}
         }
 
-        let adjust = pat_adjust_pos(variant.fields.len(), subpats.len(), ddpos);
         if subpats.len() == variant.fields.len() ||
                 subpats.len() < variant.fields.len() && ddpos.is_some() {
-            for (i, subpat) in subpats.iter().enumerate() {
-                let field_ty = self.field_ty(subpat.span,
-                                    &variant.fields[adjust(i)], expected_substs);
+            for (i, subpat) in subpats.iter().enumerate_and_adjust(variant.fields.len(), ddpos) {
+                let field_ty = self.field_ty(subpat.span, &variant.fields[i], expected_substs);
                 self.check_pat(&subpat, field_ty);
             }
         } else {

src/librustc_typeck/lib.rs

@@ -77,12 +77,11 @@ This API is completely unstable and subject to change.
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(iter_arith)]
-#![feature(question_mark)]
 #![feature(quote)]
 #![feature(rustc_diagnostic_macros)]
 #![feature(rustc_private)]
 #![feature(staged_api)]
-#![feature(type_ascription)]
+#![feature(question_mark)]
 
 #[macro_use] extern crate log;
 #[macro_use] extern crate syntax;