vec_len(/* length */ uint, VecLenOpt, /*range of matches*/(uint, uint))
}
+fn lit_to_expr(tcx: &ty::ctxt, a: &Lit) -> @ast::Expr {
+ match *a {
+ ExprLit(existing_a_expr) => existing_a_expr,
+ ConstLit(a_const) => const_eval::lookup_const_by_id(tcx, a_const).unwrap(),
+ UnitLikeStructLit(_) => fail!("lit_to_expr: unexpected struct lit"),
+ }
+}
+
fn opt_eq(tcx: &ty::ctxt, a: &Opt, b: &Opt) -> bool {
match (a, b) {
+ (&lit(UnitLikeStructLit(a)), &lit(UnitLikeStructLit(b))) => a == b,
(&lit(a), &lit(b)) => {
- match (a, b) {
- (UnitLikeStructLit(a), UnitLikeStructLit(b)) => a == b,
- _ => {
- let a_expr;
- match a {
- ExprLit(existing_a_expr) => a_expr = existing_a_expr,
- ConstLit(a_const) => {
- let e = const_eval::lookup_const_by_id(tcx, a_const);
- a_expr = e.unwrap();
- }
- UnitLikeStructLit(_) => {
- fail!("UnitLikeStructLit should have been handled \
- above")
- }
- }
-
- let b_expr;
- match b {
- ExprLit(existing_b_expr) => b_expr = existing_b_expr,
- ConstLit(b_const) => {
- let e = const_eval::lookup_const_by_id(tcx, b_const);
- b_expr = e.unwrap();
- }
- UnitLikeStructLit(_) => {
- fail!("UnitLikeStructLit should have been handled \
- above")
- }
- }
-
- match const_eval::compare_lit_exprs(tcx, a_expr, b_expr) {
- Some(val1) => val1 == 0,
- None => fail!("compare_list_exprs: type mismatch"),
- }
- }
+ let a_expr = lit_to_expr(tcx, &a);
+ let b_expr = lit_to_expr(tcx, &b);
+ match const_eval::compare_lit_exprs(tcx, a_expr, b_expr) {
+ Some(val1) => val1 == 0,
+ None => fail!("compare_list_exprs: type mismatch"),
}
}
(&range(a1, a2), &range(b1, b2)) => {
}
}
+fn opt_overlap(tcx: &ty::ctxt, a: &Opt, b: &Opt) -> bool {
+ match (a, b) {
+ (&lit(a), &lit(b)) => {
+ let a_expr = lit_to_expr(tcx, &a);
+ let b_expr = lit_to_expr(tcx, &b);
+ match const_eval::compare_lit_exprs(tcx, a_expr, b_expr) {
+ Some(val1) => val1 == 0,
+ None => fail!("opt_overlap: type mismatch"),
+ }
+ }
+
+ (&range(a1, a2), &range(b1, b2)) => {
+ let m1 = const_eval::compare_lit_exprs(tcx, a1, b2);
+ let m2 = const_eval::compare_lit_exprs(tcx, b1, a2);
+ match (m1, m2) {
+ // two ranges [a1, a2] and [b1, b2] overlap iff:
+ // a1 <= b2 && b1 <= a2
+ (Some(val1), Some(val2)) => (val1 <= 0 && val2 <= 0),
+ _ => fail!("opt_overlap: type mismatch"),
+ }
+ }
+
+ (&range(a1, a2), &lit(b)) | (&lit(b), &range(a1, a2)) => {
+ let b_expr = lit_to_expr(tcx, &b);
+ let m1 = const_eval::compare_lit_exprs(tcx, a1, b_expr);
+ let m2 = const_eval::compare_lit_exprs(tcx, a2, b_expr);
+ match (m1, m2) {
+ // b is in range [a1, a2] iff a1 <= b and b <= a2
+ (Some(val1), Some(val2)) => (val1 <= 0 && 0 <= val2),
+ _ => fail!("opt_overlap: type mismatch"),
+ }
+ }
+ _ => fail!("opt_overlap: expect lit or range")
+ }
+}
+
pub enum opt_result<'a> {
single_result(Result<'a>),
lower_bound(Result<'a>),
}
}
-type enter_pat<'a> = 'a |@ast::Pat| -> Option<Vec<@ast::Pat> >;
+type enter_pat<'a> = 'a |@ast::Pat| -> Option<Vec<@ast::Pat>>;
fn enter_match<'r,'b>(
bcx: &'b Block<'b>,
let tcx = bcx.tcx();
let dummy = @ast::Pat {id: 0, node: ast::PatWild, span: DUMMY_SP};
let mut i = 0;
+ // By the virtue of fact that we are in `trans` already, `enter_opt` is able
+ // to prune sub-match tree aggressively based on exact equality. But when it
+ // comes to literal or range, that strategy may lead to wrong result if there
+ // are guard function or multiple patterns inside tuple; in that case, pruning
+ // based on the overlap of patterns is required.
+ //
+ // Ideally, when constructing the sub-match tree for certain arm, only those
+ // arms beneath it matter. But that isn't how algorithm works right now and
+ // all other arms are taken into consideration when computing `guarded` below.
+ // That is ok since each round of `compile_submatch` guarantees to trim one
+ // "column" of arm patterns and the algorithm will converge.
+ let guarded = m.iter().any(|x| x.data.arm.guard.is_some());
+ let multi_pats = m.len() > 0 && m[0].pats.len() > 1;
enter_match(bcx, tcx.def_map, m, col, val, |p| {
let answer = match p.node {
ast::PatEnum(..) |
ast::PatIdent(_, _, None) if pat_is_const(tcx.def_map, p) => {
let const_def = tcx.def_map.borrow().get_copy(&p.id);
let const_def_id = ast_util::def_id_of_def(const_def);
- if opt_eq(tcx, &lit(ConstLit(const_def_id)), opt) {
- Some(Vec::new())
- } else {
- None
+ let konst = lit(ConstLit(const_def_id));
+ match guarded || multi_pats {
+ false if opt_eq(tcx, &konst, opt) => Some(Vec::new()),
+ true if opt_overlap(tcx, &konst, opt) => Some(Vec::new()),
+ _ => None,
}
}
ast::PatEnum(_, ref subpats) => {
}
}
ast::PatLit(l) => {
- if opt_eq(tcx, &lit(ExprLit(l)), opt) {Some(Vec::new())} else {None}
+ let lit_expr = lit(ExprLit(l));
+ match guarded || multi_pats {
+ false if opt_eq(tcx, &lit_expr, opt) => Some(Vec::new()),
+ true if opt_overlap(tcx, &lit_expr, opt) => Some(Vec::new()),
+ _ => None,
+ }
}
ast::PatRange(l1, l2) => {
- if opt_eq(tcx, &range(l1, l2), opt) {Some(Vec::new())} else {None}
+ let rng = range(l1, l2);
+ match guarded || multi_pats {
+ false if opt_eq(tcx, &rng, opt) => Some(Vec::new()),
+ true if opt_overlap(tcx, &rng, opt) => Some(Vec::new()),
+ _ => None,
+ }
}
ast::PatStruct(_, ref field_pats, _) => {
if opt_eq(tcx, &variant_opt(bcx, p.id), opt) {
--- /dev/null
+// Copyright 2012-2014 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.
+
+// Tests that match expression handles overlapped literal and range
+// properly in the presence of guard function.
+
+fn val() -> uint { 1 }
+
+static CONST: uint = 1;
+
+pub fn main() {
+ lit_shadow_range();
+ range_shadow_lit();
+ range_shadow_range();
+ multi_pats_shadow_lit();
+ multi_pats_shadow_range();
+ lit_shadow_multi_pats();
+ range_shadow_multi_pats();
+}
+
+fn lit_shadow_range() {
+ assert_eq!(2, match 1 {
+ 1 if false => 1,
+ 1..2 => 2,
+ _ => 3
+ });
+
+ let x = 0;
+ assert_eq!(2, match x+1 {
+ 0 => 0,
+ 1 if false => 1,
+ 1..2 => 2,
+ _ => 3
+ });
+
+ assert_eq!(2, match val() {
+ 1 if false => 1,
+ 1..2 => 2,
+ _ => 3
+ });
+
+ assert_eq!(2, match CONST {
+ 0 => 0,
+ 1 if false => 1,
+ 1..2 => 2,
+ _ => 3
+ });
+
+ // value is out of the range of second arm, should match wildcard pattern
+ assert_eq!(3, match 3 {
+ 1 if false => 1,
+ 1..2 => 2,
+ _ => 3
+ });
+}
+
+fn range_shadow_lit() {
+ assert_eq!(2, match 1 {
+ 1..2 if false => 1,
+ 1 => 2,
+ _ => 3
+ });
+
+ let x = 0;
+ assert_eq!(2, match x+1 {
+ 0 => 0,
+ 1..2 if false => 1,
+ 1 => 2,
+ _ => 3
+ });
+
+ assert_eq!(2, match val() {
+ 1..2 if false => 1,
+ 1 => 2,
+ _ => 3
+ });
+
+ assert_eq!(2, match CONST {
+ 0 => 0,
+ 1..2 if false => 1,
+ 1 => 2,
+ _ => 3
+ });
+
+ // ditto
+ assert_eq!(3, match 3 {
+ 1..2 if false => 1,
+ 1 => 2,
+ _ => 3
+ });
+}
+
+fn range_shadow_range() {
+ assert_eq!(2, match 1 {
+ 0..2 if false => 1,
+ 1..3 => 2,
+ _ => 3,
+ });
+
+ let x = 0;
+ assert_eq!(2, match x+1 {
+ 100 => 0,
+ 0..2 if false => 1,
+ 1..3 => 2,
+ _ => 3,
+ });
+
+ assert_eq!(2, match val() {
+ 0..2 if false => 1,
+ 1..3 => 2,
+ _ => 3,
+ });
+
+ assert_eq!(2, match CONST {
+ 100 => 0,
+ 0..2 if false => 1,
+ 1..3 => 2,
+ _ => 3,
+ });
+
+ // ditto
+ assert_eq!(3, match 5 {
+ 0..2 if false => 1,
+ 1..3 => 2,
+ _ => 3,
+ });
+}
+
+fn multi_pats_shadow_lit() {
+ assert_eq!(2, match 1 {
+ 100 => 0,
+ 0 | 1..10 if false => 1,
+ 1 => 2,
+ _ => 3,
+ });
+}
+
+fn multi_pats_shadow_range() {
+ assert_eq!(2, match 1 {
+ 100 => 0,
+ 0 | 1..10 if false => 1,
+ 1..3 => 2,
+ _ => 3,
+ });
+}
+
+fn lit_shadow_multi_pats() {
+ assert_eq!(2, match 1 {
+ 100 => 0,
+ 1 if false => 1,
+ 0 | 1..10 => 2,
+ _ => 3,
+ });
+}
+
+fn range_shadow_multi_pats() {
+ assert_eq!(2, match 1 {
+ 100 => 0,
+ 1..3 if false => 1,
+ 0 | 1..10 => 2,
+ _ => 3,
+ });
+}
projects / rust.git / commitdiff