6 files changed, 155 insertions, 11 deletions

diff --git a/crates/ra_assists/src/lib.rs b/crates/ra_assists/src/lib.rs
index ded401b63..173c004cd 100644
--- a/crates/ra_assists/src/lib.rs
+++ b/crates/ra_assists/src/lib.rs
@@ -98,7 +98,7 @@ mod inline_local_variable;
 mod replace_if_let_with_match;
 mod split_import;
 mod remove_dbg;
-mod auto_import;
+pub mod auto_import;
 mod add_missing_impl_members;
 
 fn all_assists<DB: HirDatabase>() -> &'static [fn(AssistCtx<DB>) -> Option<Assist>] {
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 4411715de..f156e3f07 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -52,7 +52,7 @@ use crate::{
     db::{HirDatabase, DefDatabase},
     name::{AsName, KnownName},
     source_id::{FileAstId, AstId},
-    resolve::Resolver,
+    resolve::Resolver, resolve::ImportResolver,
 };
 
 pub use self::{
diff --git a/crates/ra_hir/src/resolve.rs b/crates/ra_hir/src/resolve.rs
index f2c85eb66..0f866e6c2 100644
--- a/crates/ra_hir/src/resolve.rs
+++ b/crates/ra_hir/src/resolve.rs
@@ -3,6 +3,8 @@ use std::sync::Arc;
 
 use rustc_hash::FxHashMap;
 
+use ra_syntax::SmolStr;
+
 use crate::{
     ModuleDef,
     code_model_api::Crate,
@@ -12,8 +14,12 @@ use crate::{
     generics::GenericParams,
     expr::{scope::{ExprScopes, ScopeId}, PatId},
     impl_block::ImplBlock,
+<<<<<<< HEAD
     path::Path,
     Trait
+=======
+    path::Path, Trait,
+>>>>>>> complete_import: add new import resolver infrastructure with some hardcoded importable name.
 };
 
 #[derive(Debug, Clone, Default)]
@@ -21,6 +27,12 @@ pub(crate) struct Resolver {
     scopes: Vec<Scope>,
 }
 
+#[derive(Debug, Clone, Default)]
+pub(crate) struct ImportResolver {
+    // todo: use fst crate or something like that
+    dummy_names: Vec<(SmolStr, Vec<SmolStr>)>,
+}
+
 // FIXME how to store these best
 #[derive(Debug, Clone)]
 pub(crate) struct ModuleItemMap {
@@ -309,3 +321,56 @@ impl Scope {
         }
     }
 }
+
+impl ImportResolver {
+    pub(crate) fn new() -> Self {
+        let dummy_names = vec![
+            (SmolStr::new("fmt"), vec![SmolStr::new("std"), SmolStr::new("fmt")]),
+            (SmolStr::new("io"), vec![SmolStr::new("std"), SmolStr::new("io")]),
+            (SmolStr::new("iter"), vec![SmolStr::new("std"), SmolStr::new("iter")]),
+            (SmolStr::new("hash"), vec![SmolStr::new("std"), SmolStr::new("hash")]),
+            (
+                SmolStr::new("Debug"),
+                vec![SmolStr::new("std"), SmolStr::new("fmt"), SmolStr::new("Debug")],
+            ),
+            (
+                SmolStr::new("Display"),
+                vec![SmolStr::new("std"), SmolStr::new("fmt"), SmolStr::new("Display")],
+            ),
+            (
+                SmolStr::new("Hash"),
+                vec![SmolStr::new("std"), SmolStr::new("hash"), SmolStr::new("Hash")],
+            ),
+            (
+                SmolStr::new("Hasher"),
+                vec![SmolStr::new("std"), SmolStr::new("hash"), SmolStr::new("Hasher")],
+            ),
+            (
+                SmolStr::new("Iterator"),
+                vec![SmolStr::new("std"), SmolStr::new("iter"), SmolStr::new("Iterator")],
+            ),
+        ];
+
+        ImportResolver { dummy_names }
+    }
+
+    // Returns a map of importable items filtered by name.
+    // The map associates item name with its full path.
+    // todo: should return Resolutions
+    pub(crate) fn all_names(
+        &self,
+        _db: &impl HirDatabase,
+        name: &Name,
+    ) -> FxHashMap<SmolStr, Vec<SmolStr>> {
+        let name = name.to_smolstr();
+        if name.len() > 1 {
+            self.dummy_names
+                .iter()
+                .filter(|(n, _)| n.as_str().contains(name.as_str()))
+                .cloned()
+                .collect()
+        } else {
+            FxHashMap::default()
+        }
+    }
+}
diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index f1bb13bc6..a6f0ab289 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -14,14 +14,19 @@ use ra_syntax::{
     ast::{self, AstNode, NameOwner},
     algo::find_node_at_offset,
     SyntaxKind::*,
+    SmolStr,
 };
 
 use crate::{
     HirDatabase, Function, Struct, Enum, Const, Static, Either, DefWithBody, PerNs, Name,
+<<<<<<< HEAD
     AsName, Module, HirFileId, Crate, Trait, Resolver, Ty,
+=======
+    AsName, Module, HirFileId, Crate, Trait, Resolver, ImportResolver,
+>>>>>>> complete_import: add new import resolver infrastructure with some hardcoded importable name.
     expr::{BodySourceMap, scope::{ScopeId, ExprScopes}},
     ids::LocationCtx,
-    expr, AstId
+    expr, AstId,
 };
 
 /// Locates the module by `FileId`. Picks topmost module in the file.
@@ -170,6 +175,7 @@ fn def_with_body_from_child_node(
 #[derive(Debug)]
 pub struct SourceAnalyzer {
     resolver: Resolver,
+    import_resolver: ImportResolver,
     body_source_map: Option<Arc<BodySourceMap>>,
     infer: Option<Arc<crate::ty::InferenceResult>>,
     scopes: Option<Arc<crate::expr::ExprScopes>>,
@@ -217,6 +223,7 @@ impl SourceAnalyzer {
         offset: Option<TextUnit>,
     ) -> SourceAnalyzer {
         let def_with_body = def_with_body_from_child_node(db, file_id, node);
+        let import_resolver = ImportResolver::new();
         if let Some(def) = def_with_body {
             let source_map = def.body_source_map(db);
             let scopes = db.expr_scopes(def);
@@ -227,6 +234,7 @@ impl SourceAnalyzer {
             let resolver = expr::resolver_for_scope(def.body(db), db, scope);
             SourceAnalyzer {
                 resolver,
+                import_resolver,
                 body_source_map: Some(source_map),
                 infer: Some(def.infer(db)),
                 scopes: Some(scopes),
@@ -237,6 +245,7 @@ impl SourceAnalyzer {
                     .ancestors()
                     .find_map(|node| try_get_resolver_for_node(db, file_id, node))
                     .unwrap_or_default(),
+                import_resolver,
                 body_source_map: None,
                 infer: None,
                 scopes: None,
@@ -323,6 +332,14 @@ impl SourceAnalyzer {
         self.resolver.all_names(db)
     }
 
+    pub fn all_import_names(
+        &self,
+        db: &impl HirDatabase,
+        name: &Name,
+    ) -> FxHashMap<SmolStr, Vec<SmolStr>> {
+        self.import_resolver.all_names(db, name)
+    }
+
     pub fn find_all_refs(&self, pat: &ast::BindPat) -> Vec<ReferenceDescriptor> {
         // FIXME: at least, this should work with any DefWithBody, but ideally
         // this should be hir-based altogether
diff --git a/crates/ra_ide_api/src/completion/complete_scope.rs b/crates/ra_ide_api/src/completion/complete_scope.rs
index fd256fc3b..63d475823 100644
--- a/crates/ra_ide_api/src/completion/complete_scope.rs
+++ b/crates/ra_ide_api/src/completion/complete_scope.rs
@@ -1,12 +1,57 @@
-use crate::completion::{Completions, CompletionContext};
+use ra_text_edit::TextEditBuilder;
+use ra_syntax::SmolStr;
+use ra_assists::auto_import;
+use crate::completion::{CompletionItem, Completions, CompletionKind, CompletionContext};
 
 pub(super) fn complete_scope(acc: &mut Completions, ctx: &CompletionContext) {
-    if !ctx.is_trivial_path {
-        return;
+    if ctx.is_trivial_path {
+        let names = ctx.analyzer.all_names(ctx.db);
+        names.into_iter().for_each(|(name, res)| acc.add_resolution(ctx, name.to_string(), &res));
     }
-    let names = ctx.analyzer.all_names(ctx.db);
 
-    names.into_iter().for_each(|(name, res)| acc.add_resolution(ctx, name.to_string(), &res));
+    if let Some(name) = ctx.path_ident.as_ref() {
+        let import_names = ctx.analyzer.all_import_names(ctx.db, name);
+        import_names.into_iter().for_each(|(name, path)| {
+            let edit = {
+                let mut builder = TextEditBuilder::default();
+                builder.replace(ctx.source_range(), name.to_string());
+                auto_import::auto_import_text_edit(
+                    ctx.token.parent(),
+                    ctx.token.parent(),
+                    &path,
+                    &mut builder,
+                );
+                builder.finish()
+            };
+            CompletionItem::new(
+                CompletionKind::Reference,
+                ctx.source_range(),
+                build_import_label(&name, &path),
+            )
+            .text_edit(edit)
+            .add_to(acc)
+        });
+    }
+}
+
+fn build_import_label(name: &str, path: &Vec<SmolStr>) -> String {
+    let mut buf = String::with_capacity(64);
+    buf.push_str(name);
+    buf.push_str(" (");
+    fmt_import_path(path, &mut buf);
+    buf.push_str(")");
+    buf
+}
+
+fn fmt_import_path(path: &Vec<SmolStr>, buf: &mut String) {
+    let mut segments = path.iter();
+    if let Some(s) = segments.next() {
+        buf.push_str(&s);
+    }
+    for s in segments {
+        buf.push_str("::");
+        buf.push_str(&s);
+    }
 }
 
 #[cfg(test)]
diff --git a/crates/ra_ide_api/src/completion/completion_context.rs b/crates/ra_ide_api/src/completion/completion_context.rs
index 359f2cffa..ca8f7900d 100644
--- a/crates/ra_ide_api/src/completion/completion_context.rs
+++ b/crates/ra_ide_api/src/completion/completion_context.rs
@@ -5,10 +5,10 @@ use ra_syntax::{
     algo::{find_token_at_offset, find_covering_element, find_node_at_offset},
     SyntaxKind::*,
 };
-use hir::source_binder;
 
-use crate::{db, FilePosition};
+use hir::{ source_binder, Name };
 
+use crate::{db, FilePosition};
 /// `CompletionContext` is created early during completion to figure out, where
 /// exactly is the cursor, syntax-wise.
 #[derive(Debug)]
@@ -27,8 +27,10 @@ pub(crate) struct CompletionContext<'a> {
     pub(super) is_pat_binding: bool,
     /// A single-indent path, like `foo`. `::foo` should not be considered a trivial path.
     pub(super) is_trivial_path: bool,
-    /// If not a trivial, path, the prefix (qualifier).
+    /// If not a trivial path, the prefix (qualifier).
     pub(super) path_prefix: Option<hir::Path>,
+    /// If a trivial path, the ident.
+    pub(super) path_ident: Option<Name>,
     pub(super) after_if: bool,
     /// `true` if we are a statement or a last expr in the block.
     pub(super) can_be_stmt: bool,
@@ -63,6 +65,7 @@ impl<'a> CompletionContext<'a> {
             is_pat_binding: false,
             is_trivial_path: false,
             path_prefix: None,
+            path_ident: None,
             after_if: false,
             can_be_stmt: false,
             is_new_item: false,
@@ -83,6 +86,18 @@ impl<'a> CompletionContext<'a> {
     }
 
     fn fill(&mut self, original_file: &'a SourceFile, offset: TextUnit) {
+        // We heed the original NameRef before the "intellijRulezz" hack
+        if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(original_file.syntax(), offset)
+        {
+            if let Some(path) = name_ref.syntax().ancestors().find_map(ast::Path::cast) {
+                if let Some(path) = hir::Path::from_ast(path) {
+                    if let Some(ident) = path.as_ident() {
+                        self.path_ident = Some(ident.clone());
+                    }
+                }
+            }
+        }
+
         // Insert a fake ident to get a valid parse tree. We will use this file
         // to determine context, though the original_file will be used for
         // actual completion.
@@ -151,6 +166,7 @@ impl<'a> CompletionContext<'a> {
             Some(it) => it,
             None => return,
         };
+
         if let Some(segment) = ast::PathSegment::cast(parent) {
             let path = segment.parent_path();
             self.is_call = path
@@ -167,6 +183,7 @@ impl<'a> CompletionContext<'a> {
                     return;
                 }
             }
+
             if path.qualifier().is_none() {
                 self.is_trivial_path = true;