From 55891be06a1f0a051638cb59f1d15167faf5ab82 Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Sat, 13 Jan 2018 13:42:19 +0300
Subject: G: use trees

---
 src/parser/event_parser/grammar/items.rs | 56 +++++++++++++++++++++++++++++++-
 src/parser/event_parser/grammar/paths.rs | 22 +++++++++----
 src/parser/mod.rs                        |  2 +-
 src/syntax_kinds.rs                      | 14 ++++----
 4 files changed, 80 insertions(+), 14 deletions(-)

(limited to 'src')

diff --git a/src/parser/event_parser/grammar/items.rs b/src/parser/event_parser/grammar/items.rs
index f7310c09a..2f64111ab 100644
--- a/src/parser/event_parser/grammar/items.rs
+++ b/src/parser/event_parser/grammar/items.rs
@@ -74,9 +74,63 @@ fn mod_item(p: &mut Parser) {
     p.curly_block(mod_contents);
 }
 
+pub(super) fn is_use_tree_start(kind: SyntaxKind) -> bool {
+    kind == STAR || kind == L_CURLY
+}
+
 fn use_item(p: &mut Parser) {
-    paths::use_path(p);
+    use_tree(p);
     p.expect(SEMI);
+
+    fn use_tree(p: &mut Parser) -> bool{
+        if node_if(p, STAR, USE_TREE, |_| ()) {
+            return true
+        }
+        if node_if(p, [COLONCOLON, STAR], USE_TREE, |_| ()) {
+           return true
+        }
+        if [COLONCOLON, L_CURLY].is_ahead(p) || L_CURLY.is_ahead(p) {
+            node(p, USE_TREE, |p| {
+                p.eat(COLONCOLON);
+                p.curly_block(|p| {
+                    comma_list(p, EOF, use_tree);
+                });
+            });
+            return true;
+        }
+        if paths::is_path_start(p) {
+            node(p, USE_TREE, |p| {
+                paths::use_path(p);
+                match p.current() {
+                    AS_KW => {
+                        alias(p);
+                    }
+                    COLONCOLON => {
+                        p.bump();
+                        match p.current() {
+                            STAR => {
+                                p.bump();
+                            }
+                            L_CURLY => {
+                                p.curly_block(|p| {
+                                    comma_list(p, EOF, use_tree);
+                                });
+                            }
+                            _ => {
+                                // is this unreachable?
+                                p.error()
+                                    .message("expected `{` or `*`")
+                                    .emit();
+                            }
+                        }
+                    }
+                    _ => (),
+                }
+            });
+            return true;
+        }
+        false
+    }
 }
 
 fn struct_field(p: &mut Parser) -> bool {
diff --git a/src/parser/event_parser/grammar/paths.rs b/src/parser/event_parser/grammar/paths.rs
index d6887a9ba..62d1a3bb2 100644
--- a/src/parser/event_parser/grammar/paths.rs
+++ b/src/parser/event_parser/grammar/paths.rs
@@ -1,7 +1,11 @@
 use super::*;
 
+pub (crate) fn is_path_start(p: &Parser) -> bool {
+    AnyOf(&[IDENT, SELF_KW, SUPER_KW, COLONCOLON]).is_ahead(p)
+}
+
 pub(crate) fn use_path(p: &mut Parser) {
-    if !AnyOf(&[IDENT, SELF_KW, SUPER_KW, COLONCOLON]).is_ahead(p) {
+    if !is_path_start(p) {
         return;
     }
     let mut prev = p.mark();
@@ -10,11 +14,17 @@ pub(crate) fn use_path(p: &mut Parser) {
     });
     many(p, |p| {
         let curr = p.mark();
-        node_if(p, COLONCOLON, PATH, |p| {
-            path_segment(p, false);
-            p.forward_parent(prev, curr);
-            prev = curr;
-        })
+        if p.current() == COLONCOLON && !items::is_use_tree_start(p.raw_lookahead(1)) {
+            node(p, PATH, |p| {
+                p.bump();
+                path_segment(p, false);
+                p.forward_parent(prev, curr);
+                prev = curr;
+            });
+            true
+        } else {
+            false
+        }
     });
 }
 
diff --git a/src/parser/mod.rs b/src/parser/mod.rs
index c08d32d08..0c29442f9 100644
--- a/src/parser/mod.rs
+++ b/src/parser/mod.rs
@@ -29,7 +29,7 @@ fn from_events_to_file(
         }
 
         match event {
-            &Event::Start { kind, forward_parent } => {
+            &Event::Start { .. } => {
                 forward_parents.clear();
                 let mut idx = i;
                 loop {
diff --git a/src/syntax_kinds.rs b/src/syntax_kinds.rs
index 48f55fa97..8bc63a210 100644
--- a/src/syntax_kinds.rs
+++ b/src/syntax_kinds.rs
@@ -77,13 +77,14 @@ pub const ATTR: SyntaxKind = SyntaxKind(72);
 pub const META_ITEM: SyntaxKind = SyntaxKind(73);
 pub const MOD_ITEM: SyntaxKind = SyntaxKind(74);
 pub const USE_ITEM: SyntaxKind = SyntaxKind(75);
-pub const PATH: SyntaxKind = SyntaxKind(76);
-pub const PATH_SEGMENT: SyntaxKind = SyntaxKind(77);
-pub const LITERAL: SyntaxKind = SyntaxKind(78);
-pub const ALIAS: SyntaxKind = SyntaxKind(79);
-pub const VISIBILITY: SyntaxKind = SyntaxKind(80);
+pub const USE_TREE: SyntaxKind = SyntaxKind(76);
+pub const PATH: SyntaxKind = SyntaxKind(77);
+pub const PATH_SEGMENT: SyntaxKind = SyntaxKind(78);
+pub const LITERAL: SyntaxKind = SyntaxKind(79);
+pub const ALIAS: SyntaxKind = SyntaxKind(80);
+pub const VISIBILITY: SyntaxKind = SyntaxKind(81);
 
-static INFOS: [SyntaxInfo; 81] = [
+static INFOS: [SyntaxInfo; 82] = [
     SyntaxInfo { name: "USE_KW" },
     SyntaxInfo { name: "FN_KW" },
     SyntaxInfo { name: "STRUCT_KW" },
@@ -160,6 +161,7 @@ static INFOS: [SyntaxInfo; 81] = [
     SyntaxInfo { name: "META_ITEM" },
     SyntaxInfo { name: "MOD_ITEM" },
     SyntaxInfo { name: "USE_ITEM" },
+    SyntaxInfo { name: "USE_TREE" },
     SyntaxInfo { name: "PATH" },
     SyntaxInfo { name: "PATH_SEGMENT" },
     SyntaxInfo { name: "LITERAL" },
-- 
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