From 7cdf990c40e932a466e8799ca3fa582467d32c91 Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Fri, 2 Feb 2018 22:21:06 +0300
Subject: Move use item parsing to a separate file

---
 src/parser/event_parser/grammar/items/use_item.rs | 66 +++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 src/parser/event_parser/grammar/items/use_item.rs

(limited to 'src/parser/event_parser/grammar/items/use_item.rs')

diff --git a/src/parser/event_parser/grammar/items/use_item.rs b/src/parser/event_parser/grammar/items/use_item.rs
new file mode 100644
index 000000000..38e7b3f8a
--- /dev/null
+++ b/src/parser/event_parser/grammar/items/use_item.rs
@@ -0,0 +1,66 @@
+use super::*;
+
+pub(super) fn use_item(p: &mut Parser) {
+    assert!(p.at(USE_KW));
+    p.bump();
+    use_tree(p);
+    p.expect(SEMI);
+}
+
+fn use_tree(p: &mut Parser) {
+    let la = p.nth(1);
+    let m = p.start();
+    match (p.current(), la) {
+        (STAR, _) => p.bump(),
+        (COLONCOLON, STAR) => {
+            p.bump();
+            p.bump();
+        }
+        (L_CURLY, _) | (COLONCOLON, L_CURLY) => {
+            if p.at(COLONCOLON) {
+                p.bump();
+            }
+            nested_trees(p);
+        }
+        _ if paths::is_path_start(p) => {
+            paths::use_path(p);
+            match p.current() {
+                AS_KW => {
+                    alias(p);
+                }
+                COLONCOLON => {
+                    p.bump();
+                    match p.current() {
+                        STAR => {
+                            p.bump();
+                        }
+                        L_CURLY => nested_trees(p),
+                        _ => {
+                            // is this unreachable?
+                            p.error().message("expected `{` or `*`").emit();
+                        }
+                    }
+                }
+                _ => (),
+            }
+        }
+        _ => {
+            m.abandon(p);
+            p.err_and_bump("expected one of `*`, `::`, `{`, `self`, `super`, `indent`");
+            return;
+        }
+    }
+    m.complete(p, USE_TREE);
+}
+
+fn nested_trees(p: &mut Parser) {
+    assert!(p.at(L_CURLY));
+    p.bump();
+    while !p.at(EOF) && !p.at(R_CURLY) {
+        use_tree(p);
+        if !p.at(R_CURLY) {
+            p.expect(COMMA);
+        }
+    }
+    p.expect(R_CURLY);
+}
-- 
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