From 4e4ad3d27cd662b790395b61f3cda560fd4e2146 Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Sat, 4 Aug 2018 15:47:45 +0300
Subject: tuple patterns

---
 src/grammar/patterns.rs | 92 ++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 88 insertions(+), 4 deletions(-)

(limited to 'src/grammar/patterns.rs')

diff --git a/src/grammar/patterns.rs b/src/grammar/patterns.rs
index 7216807fd..770274686 100644
--- a/src/grammar/patterns.rs
+++ b/src/grammar/patterns.rs
@@ -1,14 +1,98 @@
 use super::*;
 
 pub(super) fn pattern(p: &mut Parser) {
-    match p.current() {
+    let la0 = p.nth(0);
+    let la1 = p.nth(1);
+    if la0 == REF_KW || la0 == MUT_KW
+        || (la0 == IDENT && !(la1 == COLONCOLON || la1 == L_PAREN || la1 == L_CURLY)) {
+        bind_pat(p, true);
+        return;
+    }
+    if paths::is_path_start(p) {
+        path_pat(p);
+        return;
+    }
+
+    match la0 {
         UNDERSCORE => placeholder_pat(p),
         AMPERSAND => ref_pat(p),
-        IDENT | REF_KW | MUT_KW => bind_pat(p),
         _ => p.err_and_bump("expected pattern"),
     }
 }
 
+// test path_part
+// fn foo() {
+//     let foo::Bar = ();
+//     let ::Bar = ();
+//     let Bar { .. } = ();
+//     let Bar(..) = ();
+// }
+fn path_pat(p: &mut Parser) {
+    let m = p.start();
+    paths::expr_path(p);
+    let kind = match p.current() {
+        L_PAREN => {
+            tuple_pat_fields(p);
+            TUPLE_PAT
+        }
+        L_CURLY => {
+            struct_pat_fields(p);
+            STRUCT_PAT
+        }
+        _ => PATH_PAT
+    };
+    m.complete(p, kind);
+}
+
+// test tuple_pat_fields
+// fn foo() {
+//     let S() = ();
+//     let S(_) = ();
+//     let S(_,) = ();
+//     let S(_, .. , x) = ();
+// }
+fn tuple_pat_fields(p: &mut Parser) {
+    assert!(p.at(L_PAREN));
+    p.bump();
+    while !p.at(EOF) && !p.at(R_PAREN) {
+        match p.current() {
+            DOTDOT => p.bump(),
+            _ => pattern(p),
+        }
+        if !p.at(R_PAREN) {
+            p.expect(COMMA);
+        }
+    }
+    p.expect(R_PAREN);
+}
+
+// test struct_pat_fields
+// fn foo() {
+//     let S {} = ();
+//     let S { f, ref mut g } = ();
+//     let S { h: _, ..} = ();
+//     let S { h: _, } = ();
+// }
+fn struct_pat_fields(p: &mut Parser) {
+    assert!(p.at(L_CURLY));
+    p.bump();
+    while !p.at(EOF) && !p.at(R_CURLY) {
+        match p.current() {
+            DOTDOT => p.bump(),
+            IDENT if p.nth(1) == COLON => {
+                p.bump();
+                p.bump();
+                pattern(p);
+            }
+            _ => bind_pat(p, false),
+        }
+        if !p.at(R_CURLY) {
+            p.expect(COMMA);
+        }
+    }
+    p.expect(R_CURLY);
+}
+
 // test placeholder_pat
 // fn main() { let _ = (); }
 fn placeholder_pat(p: &mut Parser) {
@@ -41,12 +125,12 @@ fn ref_pat(p: &mut Parser) {
 //     let e @ _ = ();
 //     let ref mut f @ g @ _ = ();
 // }
-fn bind_pat(p: &mut Parser) {
+fn bind_pat(p: &mut Parser, with_at: bool) {
     let m = p.start();
     p.eat(REF_KW);
     p.eat(MUT_KW);
     name(p);
-    if p.eat(AT) {
+    if with_at && p.eat(AT) {
         pattern(p);
     }
     m.complete(p, BIND_PAT);
-- 
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