From 56c7145993f94a12bf923f08cbd62d963e62bbd1 Mon Sep 17 00:00:00 2001
From: Jonas Schievink <jonas.schievink@ferrous-systems.com>
Date: Wed, 10 Jun 2020 12:30:33 +0200
Subject: Limit import map queries

---
 crates/ra_hir_def/src/import_map.rs | 42 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

(limited to 'crates/ra_hir_def/src')

diff --git a/crates/ra_hir_def/src/import_map.rs b/crates/ra_hir_def/src/import_map.rs
index f2e4ca2db..70368d8df 100644
--- a/crates/ra_hir_def/src/import_map.rs
+++ b/crates/ra_hir_def/src/import_map.rs
@@ -178,11 +178,12 @@ fn cmp((_, lhs): &(&ItemInNs, &ModPath), (_, rhs): &(&ItemInNs, &ModPath)) -> Or
 pub struct Query {
     query: String,
     anchor_end: bool,
+    limit: usize,
 }
 
 impl Query {
     pub fn new(query: &str) -> Self {
-        Self { query: query.to_lowercase(), anchor_end: false }
+        Self { query: query.to_lowercase(), anchor_end: false, limit: usize::max_value() }
     }
 
     /// Only returns items whose paths end with the (case-insensitive) query string as their last
@@ -190,6 +191,11 @@ impl Query {
     pub fn anchor_end(self) -> Self {
         Self { anchor_end: true, ..self }
     }
+
+    /// Limits the returned number of items to `limit`.
+    pub fn limit(self, limit: usize) -> Self {
+        Self { limit, ..self }
+    }
 }
 
 /// Searches dependencies of `krate` for an importable path matching `query`.
@@ -237,6 +243,11 @@ pub fn search_dependencies<'a>(
                 let item_path = &import_map.map[item];
                 fst_path(item_path) == fst_path(path)
             }));
+
+            if res.len() >= query.limit {
+                res.truncate(query.limit);
+                return res;
+            }
         }
     }
 
@@ -570,4 +581,33 @@ mod tests {
         dep::Fmt (m)
         "###);
     }
+
+    #[test]
+    fn search_limit() {
+        let res = search_dependencies_of(
+            r#"
+        //- /main.rs crate:main deps:dep
+        //- /dep.rs crate:dep
+        pub mod fmt {
+            pub trait Display {
+                fn fmt();
+            }
+        }
+        #[macro_export]
+        macro_rules! Fmt {
+            () => {};
+        }
+        pub struct Fmt;
+
+        pub fn format() {}
+        pub fn no() {}
+    "#,
+            "main",
+            Query::new("").limit(2),
+        );
+        assert_snapshot!(res, @r###"
+        dep::fmt (t)
+        dep::Fmt (t)
+        "###);
+    }
 }
-- 
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