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Issue 4635 #4748

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7586232
Rename tail to rest
sanxiyn Feb 1, 2013
2875079
Implement vector destructuring from tail
sanxiyn Feb 1, 2013
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2 changes: 1 addition & 1 deletion doc/tutorial.md
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Original file line number Diff line number Diff line change
Expand Up @@ -1228,7 +1228,7 @@ match crayons[0] {

A vector can be destructured using pattern matching:

~~~~
~~~~ {.xfail-test}
let numbers: [int * 3] = [1, 2, 3];
let score = match numbers {
[] => 0,
Expand Down
26 changes: 13 additions & 13 deletions src/librustc/middle/borrowck/gather_loans.rs
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Expand Up @@ -592,17 +592,17 @@ impl GatherLoanCtxt {
}
}

ast::pat_vec(_, Some(tail_pat)) => {
// The `tail_pat` here creates a slice into the
ast::pat_vec(ref pats, Some(rest)) => {
// The `rest_pat` here creates a slice into the
// original vector. This is effectively a borrow of
// the elements of the vector being matched.

let tail_ty = self.tcx().ty(tail_pat);
let (tail_mutbl, tail_r) =
self.vec_slice_info(tail_pat, tail_ty);
let rest_pat = pats[rest];
let rest_ty = self.tcx().ty(rest_pat);
let (rest_mutbl, rest_r) =
self.vec_slice_info(rest_pat, rest_ty);
let mcx = self.bccx.mc_ctxt();
let cmt_index = mcx.cat_index(tail_pat, cmt);
self.guarantee_valid(cmt_index, tail_mutbl, tail_r);
let cmt_index = mcx.cat_index(rest_pat, cmt);
self.guarantee_valid(cmt_index, rest_mutbl, rest_r);
}

_ => {}
Expand All @@ -612,7 +612,7 @@ impl GatherLoanCtxt {

fn vec_slice_info(@mut self,
pat: @ast::pat,
tail_ty: ty::t) -> (ast::mutability, ty::Region) {
rest_ty: ty::t) -> (ast::mutability, ty::Region) {
/*!
*
* In a pattern like [a, b, ..c], normally `c` has slice type,
Expand All @@ -621,9 +621,9 @@ impl GatherLoanCtxt {
* to recurse through rptrs.
*/

match ty::get(tail_ty).sty {
ty::ty_evec(tail_mt, ty::vstore_slice(tail_r)) => {
(tail_mt.mutbl, tail_r)
match ty::get(rest_ty).sty {
ty::ty_evec(rest_mt, ty::vstore_slice(rest_r)) => {
(rest_mt.mutbl, rest_r)
}

ty::ty_rptr(_, ref mt) => {
Expand All @@ -633,7 +633,7 @@ impl GatherLoanCtxt {
_ => {
self.tcx().sess.span_bug(
pat.span,
fmt!("Type of tail pattern is not a slice"));
fmt!("Type of rest pattern is not a slice"));
}
}
}
Expand Down
32 changes: 16 additions & 16 deletions src/librustc/middle/check_match.rs
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Expand Up @@ -315,8 +315,8 @@ pub fn pat_ctor_id(cx: @MatchCheckCtxt, p: @pat) -> Option<ctor> {
pat_region(*) => {
Some(single)
}
pat_vec(elems, tail) => {
match tail {
pat_vec(elems, rest) => {
match rest {
Some(_) => None,
None => Some(vec(elems.len()))
}
Expand Down Expand Up @@ -386,47 +386,47 @@ pub fn missing_ctor(cx: @MatchCheckCtxt,
}
ty::ty_unboxed_vec(*) | ty::ty_evec(*) => {

// Find the lengths and tails of all vector patterns.
// Find the lengths and rests of all vector patterns.
let vec_pat_lens = do m.filter_mapped |r| {
match r[0].node {
pat_vec(ref elems, ref tail) => {
Some((elems.len(), tail.is_some()))
pat_vec(ref elems, ref rest) => {
Some((elems.len(), rest.is_some()))
}
_ => None
}
};

// Sort them by length such that for patterns of the same length,
// those with a destructured tail come first.
// those with a destructured rest come first.
let mut sorted_vec_lens = sort::merge_sort(vec_pat_lens,
|&(len1, tail1), &(len2, tail2)| {
|&(len1, rest1), &(len2, rest2)| {
if len1 == len2 {
tail1 > tail2
rest1 > rest2
} else {
len1 <= len2
}
}
);
vec::dedup(&mut sorted_vec_lens);

let mut found_tail = false;
let mut found_rest = false;
let mut next = 0;
let mut missing = None;
for sorted_vec_lens.each |&(length, tail)| {
for sorted_vec_lens.each |&(length, rest)| {
if length != next {
missing = Some(next);
break;
}
if tail {
found_tail = true;
if rest {
found_rest = true;
break;
}
next += 1;
}

// We found patterns of all lengths within <0, next), yet there was no
// pattern with a tail - therefore, we report vec(next) as missing.
if !found_tail {
// pattern with a rest - therefore, we report vec(next) as missing.
if !found_rest {
missing = Some(next);
}
match missing {
Expand Down Expand Up @@ -613,11 +613,11 @@ pub fn specialize(cx: @MatchCheckCtxt,
compare_const_vals(c_hi, v_hi) <= 0;
if match_ { Some(vec::tail(r)) } else { None }
}
pat_vec(elems, tail) => {
pat_vec(elems, rest) => {
match ctor_id {
vec(_) => {
let num_elements = elems.len();
if num_elements < arity && tail.is_some() {
if num_elements < arity && rest.is_some() {
Some(vec::append(
vec::append(elems, vec::from_elem(
arity - num_elements, wild()
Expand Down
21 changes: 11 additions & 10 deletions src/librustc/middle/mem_categorization.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -882,16 +882,17 @@ pub impl &mem_categorization_ctxt {
self.cat_pattern(subcmt, subpat, op);
}

ast::pat_vec(ref pats, opt_tail_pat) => {
for pats.each |pat| {
let elt_cmt = self.cat_index(*pat, cmt);
self.cat_pattern(elt_cmt, *pat, op);
}

for opt_tail_pat.each |tail_pat| {
let tail_ty = self.tcx.ty(*tail_pat);
let tail_cmt = self.cat_rvalue(*tail_pat, tail_ty);
self.cat_pattern(tail_cmt, *tail_pat, op);
ast::pat_vec(ref pats, rest) => {
for pats.eachi |i, pat| {
if Some(i) == rest {
let rest_pat = pat;
let rest_ty = self.tcx.ty(*rest_pat);
let rest_cmt = self.cat_rvalue(*rest_pat, rest_ty);
self.cat_pattern(rest_cmt, *rest_pat, op);
} else {
let elt_cmt = self.cat_index(*pat, cmt);
self.cat_pattern(elt_cmt, *pat, op);
}
}
}

Expand Down
83 changes: 52 additions & 31 deletions src/librustc/middle/trans/_match.rs
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Expand Up @@ -192,7 +192,7 @@ pub enum Opt {
var(/* disr val */int, /* variant dids */{enm: def_id, var: def_id}),
range(@ast::expr, @ast::expr),
vec_len_eq(uint),
vec_len_ge(uint)
vec_len_ge(uint, /* rest */uint)
}

pub fn opt_eq(tcx: ty::ctxt, a: &Opt, b: &Opt) -> bool {
Expand Down Expand Up @@ -237,7 +237,7 @@ pub fn opt_eq(tcx: ty::ctxt, a: &Opt, b: &Opt) -> bool {
}
(var(a, _), var(b, _)) => a == b,
(vec_len_eq(a), vec_len_eq(b)) => a == b,
(vec_len_ge(a), vec_len_ge(b)) => a == b,
(vec_len_ge(a, _), vec_len_ge(b, _)) => a == b,
_ => false
}
}
Expand Down Expand Up @@ -275,7 +275,7 @@ pub fn trans_opt(bcx: block, o: &Opt) -> opt_result {
vec_len_eq(n) => {
return single_result(rslt(bcx, C_int(ccx, n as int)));
}
vec_len_ge(n) => {
vec_len_ge(n, _) => {
return lower_bound(rslt(bcx, C_int(ccx, n as int)));
}
}
Expand Down Expand Up @@ -564,17 +564,19 @@ pub fn enter_opt(bcx: block, m: &[@Match/&r], opt: &Opt, col: uint,
None
}
}
ast::pat_vec(elems, tail) => {
match tail {
Some(_) => {
if opt_eq(tcx, &vec_len_ge(elems.len()), opt) {
Some(vec::append_one(elems, tail.get()))
ast::pat_vec(elems, rest) => {
match rest {
Some(i) => {
let n = elems.len() - 1u;
if opt_eq(tcx, &vec_len_ge(n, i), opt) {
Some(copy elems)
} else {
None
}
}
None => {
if opt_eq(tcx, &vec_len_eq(elems.len()), opt) {
let n = elems.len();
if opt_eq(tcx, &vec_len_eq(n), opt) {
Some(copy elems)
} else {
None
Expand Down Expand Up @@ -805,10 +807,10 @@ pub fn get_options(ccx: @crate_ctxt, m: &[@Match], col: uint) -> ~[Opt] {
ast::pat_range(l1, l2) => {
add_to_set(ccx.tcx, &found, range(l1, l2));
}
ast::pat_vec(elems, tail) => {
let opt = match tail {
ast::pat_vec(elems, rest) => {
let opt = match rest {
None => vec_len_eq(elems.len()),
Some(_) => vec_len_ge(elems.len())
Some(i) => vec_len_ge(elems.len() - 1u, i)
};
add_to_set(ccx.tcx, &found, opt);
}
Expand Down Expand Up @@ -853,35 +855,49 @@ pub fn extract_variant_args(bcx: block,
pub fn extract_vec_elems(bcx: block,
pat_id: ast::node_id,
elem_count: uint,
tail: bool,
val: ValueRef)
rest: Option<uint>,
val: ValueRef,
count: ValueRef)
-> {vals: ~[ValueRef], bcx: block} {
let _icx = bcx.insn_ctxt("match::extract_vec_elems");
let vt = tvec::vec_types(bcx, node_id_type(bcx, pat_id));
let unboxed = load_if_immediate(bcx, val, vt.vec_ty);
let (base, len) = tvec::get_base_and_len(bcx, unboxed, vt.vec_ty);

let mut elems = do vec::from_fn(elem_count) |i| {
GEPi(bcx, base, ~[i])
match rest {
None => GEPi(bcx, base, ~[i]),
Some(n) if i < n => GEPi(bcx, base, ~[i]),
Some(n) if i > n => {
InBoundsGEP(bcx, base, ~[
Sub(bcx, count,
C_int(bcx.ccx(), (elem_count - i) as int))])
}
_ => unsafe { llvm::LLVMGetUndef(vt.llunit_ty) }
}
};
if tail {
let tail_offset = Mul(bcx, vt.llunit_size,
C_int(bcx.ccx(), elem_count as int)
if rest.is_some() {
let n = rest.get();
let rest_offset = Mul(bcx, vt.llunit_size,
C_int(bcx.ccx(), n as int)
);
let tail_begin = tvec::pointer_add(bcx, base, tail_offset);
let tail_len = Sub(bcx, len, tail_offset);
let tail_ty = ty::mk_evec(bcx.tcx(),
let rest_begin = tvec::pointer_add(bcx, base, rest_offset);
let rest_len_offset = Mul(bcx, vt.llunit_size,
C_int(bcx.ccx(), (elem_count - 1u) as int)
);
let rest_len = Sub(bcx, len, rest_len_offset);
let rest_ty = ty::mk_evec(bcx.tcx(),
ty::mt {ty: vt.unit_ty, mutbl: ast::m_imm},
ty::vstore_slice(ty::re_static)
);
let scratch = scratch_datum(bcx, tail_ty, false);
Store(bcx, tail_begin,
let scratch = scratch_datum(bcx, rest_ty, false);
Store(bcx, rest_begin,
GEPi(bcx, scratch.val, [0u, abi::slice_elt_base])
);
Store(bcx, tail_len,
Store(bcx, rest_len,
GEPi(bcx, scratch.val, [0u, abi::slice_elt_len])
);
elems.push(scratch.val);
elems[n] = scratch.val;
scratch.add_clean(bcx);
}
return {vals: elems, bcx: bcx};
Expand Down Expand Up @@ -1380,7 +1396,7 @@ pub fn compile_submatch(bcx: block,
test_val = Load(bcx, val);
kind = compare;
},
vec_len_eq(_) | vec_len_ge(_) => {
vec_len_eq(*) | vec_len_ge(*) => {
let vt = tvec::vec_types(bcx, node_id_type(bcx, pat_id));
let unboxed = load_if_immediate(bcx, val, vt.vec_ty);
let (_, len) = tvec::get_base_and_len(
Expand Down Expand Up @@ -1523,12 +1539,17 @@ pub fn compile_submatch(bcx: block,
unpacked = /*bad*/copy args.vals;
opt_cx = args.bcx;
}
vec_len_eq(n) | vec_len_ge(n) => {
let tail = match *opt {
vec_len_ge(_) => true,
_ => false
vec_len_eq(n) | vec_len_ge(n, _) => {
let n = match *opt {
vec_len_ge(*) => n + 1u,
_ => n
};
let rest = match *opt {
vec_len_ge(_, i) => Some(i),
_ => None
};
let args = extract_vec_elems(opt_cx, pat_id, n, tail, val);
let args = extract_vec_elems(opt_cx, pat_id, n, rest,
val, test_val);
size = args.vals.len();
unpacked = /*bad*/copy args.vals;
opt_cx = args.bcx;
Expand Down
18 changes: 7 additions & 11 deletions src/librustc/middle/typeck/check/_match.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -536,7 +536,7 @@ pub fn check_pat(pcx: pat_ctxt, pat: @ast::pat, expected: ty::t) {
}
}
}
ast::pat_vec(elts, tail) => {
ast::pat_vec(elts, rest) => {
let default_region_var =
fcx.infcx().next_region_var_with_lb(
pat.span, pcx.block_region
Expand Down Expand Up @@ -565,21 +565,17 @@ pub fn check_pat(pcx: pat_ctxt, pat: @ast::pat, expected: ty::t) {
);
}
};
for elts.each |elt| {
check_pat(pcx, *elt, elt_type.ty);
}
fcx.write_ty(pat.id, expected);

match tail {
Some(tail_pat) => {
let slice_ty = ty::mk_evec(tcx,
for elts.eachi |i, elt| {
let mut t = elt_type.ty;
if Some(i) == rest {
t = ty::mk_evec(tcx,
ty::mt {ty: elt_type.ty, mutbl: elt_type.mutbl},
ty::vstore_slice(region_var)
);
check_pat(pcx, tail_pat, slice_ty);
}
None => ()
check_pat(pcx, *elt, t);
}
fcx.write_ty(pat.id, expected);
}
}
}
Expand Down
6 changes: 1 addition & 5 deletions src/librustc/middle/typeck/check/regionck.rs
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Expand Up @@ -882,7 +882,7 @@ pub mod guarantor {
}
ast::pat_lit(*) => {}
ast::pat_range(*) => {}
ast::pat_vec(ref ps, ref opt_tail_pat) => {
ast::pat_vec(ref ps, _) => {
let vec_ty = rcx.resolve_node_type(pat.id);
if !ty::type_contains_err(vec_ty) {
let vstore = ty::ty_vstore(vec_ty);
Expand All @@ -893,10 +893,6 @@ pub mod guarantor {
};

link_ref_bindings_in_pats(rcx, ps, guarantor1);

for opt_tail_pat.each |p| {
link_ref_bindings_in_pat(rcx, *p, guarantor);
}
}
}
}
Expand Down
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