From a3b104aa6df205e74c116d8c9e41900807924e70 Mon Sep 17 00:00:00 2001
From: Jonas Platte <jplatte+git@posteo.de>
Date: Tue, 11 Feb 2020 22:33:11 +0100
Subject: Implement slice pattern AST > HIR lowering

---
 crates/ra_hir_def/Cargo.toml        |  1 +
 crates/ra_hir_def/src/body/lower.rs | 16 ++++++++++++----
 crates/ra_hir_def/src/expr.rs       |  6 +++---
 3 files changed, 16 insertions(+), 7 deletions(-)

(limited to 'crates/ra_hir_def')

diff --git a/crates/ra_hir_def/Cargo.toml b/crates/ra_hir_def/Cargo.toml
index 1efa00fe0..6b9be9948 100644
--- a/crates/ra_hir_def/Cargo.toml
+++ b/crates/ra_hir_def/Cargo.toml
@@ -14,6 +14,7 @@ rustc-hash = "1.0"
 either = "1.5"
 anymap = "0.12"
 drop_bomb = "0.1.4"
+itertools = "0.8.2"
 
 ra_arena = { path = "../ra_arena" }
 ra_db = { path = "../ra_db" }
diff --git a/crates/ra_hir_def/src/body/lower.rs b/crates/ra_hir_def/src/body/lower.rs
index e656f9a41..5c779521b 100644
--- a/crates/ra_hir_def/src/body/lower.rs
+++ b/crates/ra_hir_def/src/body/lower.rs
@@ -8,7 +8,7 @@ use ra_arena::Arena;
 use ra_syntax::{
     ast::{
         self, ArgListOwner, ArrayExprKind, LiteralKind, LoopBodyOwner, ModuleItemOwner, NameOwner,
-        TypeAscriptionOwner,
+        SlicePatComponents, TypeAscriptionOwner,
     },
     AstNode, AstPtr,
 };
@@ -591,7 +591,7 @@ where
                 let args = p.args().map(|p| self.collect_pat(p)).collect();
                 Pat::Tuple(args)
             }
-            ast::Pat::PlaceholderPat(_) => Pat::Wild,
+            ast::Pat::PlaceholderPat(_) | ast::Pat::DotDotPat(_) => Pat::Wild,
             ast::Pat::RecordPat(p) => {
                 let path = p.path().and_then(|path| self.expander.parse_path(path));
                 let record_field_pat_list =
@@ -616,12 +616,20 @@ where
 
                 Pat::Record { path, args: fields }
             }
+            ast::Pat::SlicePat(p) => {
+                let SlicePatComponents { prefix, slice, suffix } = p.components();
+
+                Pat::Slice {
+                    prefix: prefix.into_iter().map(|p| self.collect_pat(p)).collect(),
+                    slice: slice.map(|p| self.collect_pat(p)),
+                    suffix: suffix.into_iter().map(|p| self.collect_pat(p)).collect(),
+                }
+            }
 
             // FIXME: implement
-            ast::Pat::DotDotPat(_) => Pat::Missing,
             ast::Pat::BoxPat(_) => Pat::Missing,
             ast::Pat::LiteralPat(_) => Pat::Missing,
-            ast::Pat::SlicePat(_) | ast::Pat::RangePat(_) => Pat::Missing,
+            ast::Pat::RangePat(_) => Pat::Missing,
         };
         let ptr = AstPtr::new(&pat);
         self.alloc_pat(pattern, Either::Left(ptr))
diff --git a/crates/ra_hir_def/src/expr.rs b/crates/ra_hir_def/src/expr.rs
index a75ef9970..035824403 100644
--- a/crates/ra_hir_def/src/expr.rs
+++ b/crates/ra_hir_def/src/expr.rs
@@ -393,7 +393,7 @@ pub enum Pat {
     },
     Slice {
         prefix: Vec<PatId>,
-        rest: Option<PatId>,
+        slice: Option<PatId>,
         suffix: Vec<PatId>,
     },
     Path(Path),
@@ -424,8 +424,8 @@ impl Pat {
                 args.iter().copied().for_each(f);
             }
             Pat::Ref { pat, .. } => f(*pat),
-            Pat::Slice { prefix, rest, suffix } => {
-                let total_iter = prefix.iter().chain(rest.iter()).chain(suffix.iter());
+            Pat::Slice { prefix, slice, suffix } => {
+                let total_iter = prefix.iter().chain(slice.iter()).chain(suffix.iter());
                 total_iter.copied().for_each(f);
             }
             Pat::Record { args, .. } => {
-- 
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