Applying suggestion in Searcher (https://github.com/enso-org/ide/pull/661)

Original commit: 010e10fe30

gui/src/rust/ide/lib/ast/impl/src/prefix.rs

@@ -2,7 +2,7 @@
 
 use crate::prelude::*;
 
-use crate::{Ast, TokenConsumer};
+use crate::Ast;
 use crate::Id;
 use crate::crumbs::Located;
 use crate::crumbs::PrefixCrumb;
@@ -10,6 +10,8 @@ use crate::HasTokens;
 use crate::known;
 use crate::Prefix;
 use crate::Shifted;
+use crate::Token;
+use crate::TokenConsumer;
 
 use utils::vec::VecExt;
 
@@ -144,6 +146,16 @@ impl Chain {
     }
 }
 
+impl HasTokens for Chain {
+    fn feed_to(&self, consumer: &mut impl TokenConsumer) {
+        self.func.feed_to(consumer);
+        for arg in &self.args {
+            consumer.feed(Token::Off(arg.sast.off));
+            arg.sast.wrapped.feed_to(consumer);
+        }
+    }
+}
+
 
 
 #[cfg(test)]

gui/src/rust/ide/lib/parser/tests/ast.rs

@@ -83,6 +83,7 @@ pub fn flatten_prefix_test() {
         let ast = ast::test_utils::expect_single_line(&ast);
         let flattened = prefix::Chain::new_non_strict(&ast);
         expect_pieces(&flattened,expected_pieces);
+        assert_eq!(flattened.repr(), code);
     };
 
     case("a", vec!["a"]);

gui/src/rust/ide/src/controller/searcher.rs

@@ -7,6 +7,7 @@ use crate::notification;
 use data::text::TextLocation;
 use enso_protocol::language_server;
 use flo_stream::Subscriber;
+use parser::Parser;
 
 
 
@@ -14,11 +15,14 @@ use flo_stream::Subscriber;
 // === Suggestion List ===
 // =======================
 
+/// Suggestion for input completion: possible functions, arguments, etc.
+pub type CompletionSuggestion = Rc<model::suggestion_database::Entry>;
+
 /// A single suggestion on the Searcher suggestion list.
 #[derive(Clone,CloneRef,Debug,Eq,PartialEq)]
 pub enum Suggestion {
     /// Suggestion for input completion: possible functions, arguments, etc.
-    Completion(Rc<model::suggestion_database::Entry>)
+    Completion(CompletionSuggestion)
     // In future, other suggestion types will be added (like suggestions of actions, etc.).
 }
 
@@ -82,17 +86,133 @@ pub enum Notification {
 }
 
 
+// ===================
+// === Input Parts ===
+// ===================
+
+/// An identification of input fragment filled by picking suggestion.
+///
+/// Essentially, this is a crumb for ParsedInput's expression.
+#[derive(Clone,Copy,Debug,Eq,PartialEq)]
+#[allow(missing_docs)]
+pub enum CompletedFragmentId {
+    /// The called "function" part, defined as a `func` element in Prefix Chain
+    /// (see `ast::prefix::Chain`).
+    Function,
+    /// The `id`th argument of the called function.
+    Argument{index:usize}
+}
+
+/// A Searcher Input which is parsed to the _expression_ and _pattern_ parts.
+///
+/// We parse the input for better understanding what user wants to add.
+#[derive(Clone,Debug,Default)]
+pub struct ParsedInput {
+    /// The part of input which is treated as completed function and some set of arguments.
+    ///
+    /// The expression is kept as prefix chain, as it allows us to easily determine what kind of
+    /// entity we can put at this moment (is it a function or argument? What type of the argument?).
+    pub expression : Option<ast::Shifted<ast::prefix::Chain>>,
+    /// An offset between expression and pattern.
+    pub pattern_offset : usize,
+    /// The part of input being a function/argument which is still typed by user. It is used
+    /// for filtering suggestions.
+    pub pattern : String,
+}
+
+impl ParsedInput {
+    /// Contructor from the plain input.
+    fn new(mut input:String, parser:&Parser) -> FallibleResult<Self> {
+        let leading_spaces = input.chars().take_while(|c| *c == ' ').count();
+        // To properly guess what is "still typed argument" we simulate type of one letter by user.
+        // This letter will be added to the last argument (or function if there is no argument), or
+        // will be a new argument (so the user starts filling a new argument).
+        //
+        // See also `parsed_input` test to see all cases we want to cover.
+        input.push('a');
+        let ast        = parser.parse_line(input.trim_start())?;
+        let mut prefix = ast::prefix::Chain::new_non_strict(&ast);
+        if let Some(last_arg) = prefix.args.pop() {
+            let mut last_arg_repr = last_arg.sast.wrapped.repr();
+            last_arg_repr.pop();
+            Ok(ParsedInput {
+                expression     : Some(ast::Shifted::new(leading_spaces,prefix)),
+                pattern_offset : last_arg.sast.off,
+                pattern        : last_arg_repr,
+            })
+        } else {
+            let mut func_repr = prefix.func.repr();
+            func_repr.pop();
+            Ok(ParsedInput {
+                expression     : None,
+                pattern_offset : leading_spaces,
+                pattern        : func_repr
+            })
+        }
+    }
+
+    /// Returns the id of the next fragment potentially filled by picking completion suggestion.
+    fn next_completion_id(&self) -> CompletedFragmentId {
+        match &self.expression {
+            None             => CompletedFragmentId::Function,
+            Some(expression) => CompletedFragmentId::Argument {index:expression.args.len()},
+        }
+    }
+
+    /// Get the picked fragment from the Searcher's input.
+    pub fn completed_fragment(&self,fragment:CompletedFragmentId) -> Option<String> {
+        use CompletedFragmentId::*;
+        match (fragment,&self.expression) {
+            (_              ,None)       => None,
+            (Function       ,Some(expr)) => Some(expr.func.repr()),
+            (Argument{index},Some(expr)) => Some(expr.args.get(index)?.sast.wrapped.repr()),
+        }
+    }
+}
+
+impl HasRepr for ParsedInput {
+    fn repr(&self) -> String {
+        let mut repr = self.expression.as_ref().map_or("".to_string(), HasRepr::repr);
+        repr.extend(itertools::repeat_n(' ',self.pattern_offset));
+        repr.push_str(&self.pattern);
+        repr
+    }
+}
+
+
 
 // ===========================
 // === Searcher Controller ===
 // ===========================
 
-/// A controller state. Currently it caches the currently kept suggestions list and the current
-/// searcher input.
+/// A fragment filled by single picked completion suggestion.
+///
+/// We store such information in Searcher to better suggest the potential arguments, and to know
+/// what imports should be added when inserting node.
+#[derive(Clone,Debug)]
+#[allow(missing_docs)]
+pub struct FragmentAddedByPickingSuggestion {
+    pub id                : CompletedFragmentId,
+    pub picked_suggestion : CompletionSuggestion,
+}
+
+impl FragmentAddedByPickingSuggestion {
+    /// Check if the picked fragment is still unmodified by user.
+    fn is_still_unmodified(&self, input:&ParsedInput) -> bool {
+        input.completed_fragment(self.id).contains(&self.picked_suggestion.code_to_insert())
+    }
+}
+
+/// A controller state.
 #[derive(Clone,Debug,Default)]
-struct Data {
-    current_input : String,
-    current_list  : Suggestions,
+pub struct Data {
+    /// The current searcher's input.
+    pub input : ParsedInput,
+    /// The suggestion list which should be displayed.
+    pub suggestions : Suggestions,
+    /// All fragments of input which were added by picking suggestions. If the fragment will be
+    /// changed by user, it will be removed from this list.
+    pub fragments_added_by_picking : Vec<FragmentAddedByPickingSuggestion>,
 }
 
 /// Searcher Controller.
@@ -109,6 +229,7 @@ pub struct Searcher {
     position        : Immutable<TextLocation>,
     database        : Rc<model::SuggestionDatabase>,
     language_server : Rc<language_server::Connection>,
+    parser          : Parser,
 }
 
 impl Searcher {
@@ -127,6 +248,7 @@ impl Searcher {
             module          : Rc::new(project.qualified_module_name(&module)),
             database        : project.suggestion_db.clone_ref(),
             language_server : project.language_server_rpc.clone_ref(),
+            parser          : project.parser.clone_ref(),
         };
         this.reload_list();
         this
@@ -139,16 +261,68 @@ impl Searcher {
 
     /// Get the current suggestion list.
     pub fn suggestions(&self) -> Suggestions {
-        self.data.borrow().current_list.clone_ref()
+        self.data.borrow().suggestions.clone_ref()
     }
 
     /// Set the Searcher Input.
     ///
     /// This function should be called each time user modifies Searcher input in view. It may result
     /// in a new suggestion list (the aprriopriate notification will be emitted).
-    pub fn set_input(&self, new_input:String) {
-        self.data.borrow_mut().current_input = new_input;
-        //TODO[ao] here goes refreshing suggestion list after input change.
+    pub fn set_input(&self, new_input:String) -> FallibleResult<()> {
+        let parsed_input = ParsedInput::new(new_input,&self.parser)?;
+        let old_id       = self.data.borrow().input.next_completion_id();
+        let new_id       = parsed_input.next_completion_id();
+
+        self.data.borrow_mut().input = parsed_input;
+        self.invalidate_fragments_added_by_picking();
+        if old_id != new_id {
+            self.reload_list()
+        }
+        Ok(())
+    }
+
+    /// Pick a completion suggestion.
+    ///
+    /// This function should be called when user chooses some completion suggestion. The picked
+    /// suggestion will be remembered, and the searcher's input will be updated and returned by this
+    /// function.
+    pub fn pick_completion
+    (&self, picked_suggestion:CompletionSuggestion) -> FallibleResult<String> {
+        let added_ast         = self.parser.parse_line(&picked_suggestion.code_to_insert())?;
+        let id                = self.data.borrow().input.next_completion_id();
+        let picked_completion = FragmentAddedByPickingSuggestion {id,picked_suggestion};
+        let pattern_offset    = self.data.borrow().input.pattern_offset;
+        let new_expression    = match self.data.borrow_mut().input.expression.take() {
+            None => {
+                let ast = ast::prefix::Chain::new_non_strict(&added_ast);
+                ast::Shifted::new(pattern_offset,ast)
+            },
+            Some(mut expression) => {
+                let new_argument = ast::prefix::Argument {
+                    sast      : ast::Shifted::new(pattern_offset,added_ast),
+                    prefix_id : default(),
+                };
+                expression.args.push(new_argument);
+                expression
+            }
+        };
+        let new_parsed_input = ParsedInput {
+            expression     : Some(new_expression),
+            pattern_offset : 1,
+            pattern        : "".to_string()
+        };
+        let new_input = new_parsed_input.repr();
+        self.data.borrow_mut().input = new_parsed_input;
+        self.data.borrow_mut().fragments_added_by_picking.push(picked_completion);
+        self.reload_list();
+        Ok(new_input)
+    }
+
+    fn invalidate_fragments_added_by_picking(&self) {
+        let mut data = self.data.borrow_mut();
+        let data     = data.deref_mut();
+        let input    = &data.input;
+        data.fragments_added_by_picking.drain_filter(|frag| !frag.is_still_unmodified(input));
     }
 
     /// Reload Suggestion List.
@@ -156,23 +330,33 @@ impl Searcher {
     /// The current list will be set as "Loading" and Language Server will be requested for a new
     /// list - once it be retrieved, the new list will be set and notification will be emitted.
     fn reload_list(&self) {
+        let next_completion = self.data.borrow().input.next_completion_id();
+        let new_suggestions = if next_completion == CompletedFragmentId::Function {
+            self.get_suggestion_list_from_engine(None,None);
+            Suggestions::Loading
+        } else {
+            // TODO[ao] Requesting for argument.
+            Suggestions::Loaded {list:default()}
+        };
+        self.data.borrow_mut().suggestions = new_suggestions;
+    }
+
+    fn get_suggestion_list_from_engine
+    (&self, return_type:Option<String>, tags:Option<Vec<language_server::SuggestionEntryType>>) {
+        let ls          = &self.language_server;
         let module      = self.module.as_ref();
         let self_type   = None;
-        let return_type = None;
-        let tags        = None;
         let position    = self.position.deref().into();
-        let request     = self.language_server.completion(module,&position,&self_type,&return_type,&tags);
+        let request     = ls.completion(module,&position,&self_type,&return_type,&tags);
         let data        = self.data.clone_ref();
         let database    = self.database.clone_ref();
         let logger      = self.logger.clone_ref();
         let notifier    = self.notifier.clone_ref();
-
-        self.data.borrow_mut().current_list = Suggestions::Loading;
         executor::global::spawn(async move {
             info!(logger,"Requesting new suggestion list.");
-            let ls_response = request.await;
+            let response = request.await;
             info!(logger,"Received suggestions from Language Server.");
-            let new_list = match ls_response {
+            let new_suggestions = match response {
                 Ok(list) => {
                     let entry_ids   = list.results.into_iter();
                     let entries     = entry_ids.filter_map(|id| {
@@ -187,7 +371,7 @@ impl Searcher {
                 },
                 Err(error) => Suggestions::Error(Rc::new(error.into()))
             };
-            data.borrow_mut().current_list = new_list;
+            data.borrow_mut().suggestions = new_suggestions;
             notifier.publish(Notification::NewSuggestionList).await;
         });
     }
@@ -208,59 +392,195 @@ mod test {
     use json_rpc::expect_call;
     use utils::test::traits::*;
 
-    #[test]
-    fn reloading_list() {
-        let mut test    = TestWithLocalPoolExecutor::set_up();
-        let client      = language_server::MockClient::default();
-        let module_path = Path::from_mock_module_name("Test");
+    struct Fixture {
+        searcher : Searcher,
+        entry1   : CompletionSuggestion,
+        entry2   : CompletionSuggestion,
+        entry9   : CompletionSuggestion,
+    }
 
-        let completion_response = language_server::response::Completion {
-            results: vec![1,5,9],
-            current_version: default(),
-        };
-        expect_call!(client.completion(
-            module      = "Test.Test".to_string(),
-            position    = TextLocation::at_document_begin().into(),
-            self_type   = None,
-            return_type = None,
-            tag         = None
-        ) => Ok(completion_response));
+    impl Fixture {
+        fn new(client_setup:impl FnOnce(&mut language_server::MockClient)) -> Self {
+            let mut client  = language_server::MockClient::default();
+            let module_path = Path::from_mock_module_name("Test");
+            client_setup(&mut client);
+            let searcher = Searcher {
+                logger          : default(),
+                data            : default(),
+                notifier        : default(),
+                module          : Rc::new(module_path.qualified_module_name("Test")),
+                position        : Immutable(TextLocation::at_document_begin()),
+                database        : default(),
+                language_server : language_server::Connection::new_mock_rc(client),
+                parser          : Parser::new_or_panic(),
+            };
+            let entry1 = model::suggestion_database::Entry {
+                name          : "TestFunction1".to_string(),
+                kind          : model::suggestion_database::EntryKind::Function,
+                module        : "Test.Test".to_string().try_into().unwrap(),
+                arguments     : vec![],
+                return_type   : "Number".to_string(),
+                documentation : default(),
+                self_type     : None
+            };
+            let entry2 = model::suggestion_database::Entry {
+                name : "TestVar1".to_string(),
+                kind : model::suggestion_database::EntryKind::Local,
+                ..entry1.clone()
+            };
+            let entry9 = entry1.clone().with_name("TestFunction2");
 
-        let searcher = Searcher {
-            logger          : default(),
-            data            : default(),
-            notifier        : default(),
-            module          : Rc::new(module_path.qualified_module_name("Test")),
-            position        : Immutable(TextLocation::at_document_begin()),
-            database        : default(),
-            language_server : language_server::Connection::new_mock_rc(client),
-        };
-        let entry1 = model::suggestion_database::Entry {
-            name          : "TestFunction1".to_string(),
-            kind          : model::suggestion_database::EntryKind::Function,
-            module        : "Test.Test".to_string(),
-            arguments     : vec![],
-            return_type   : "Number".to_string(),
-            documentation : default(),
-            self_type     : None
-        };
-        let entry2 = model::suggestion_database::Entry {
-            name : "TestFunction2".to_string(),
-            ..entry1.clone()
-        };
-        searcher.database.put_entry(1,entry1);
-        let entry1 = searcher.database.get(1).unwrap();
-        searcher.database.put_entry(9,entry2);
-        let entry2 = searcher.database.get(9).unwrap();
+            searcher.database.put_entry(1,entry1);
+            let entry1 = searcher.database.get(1).unwrap();
+            searcher.database.put_entry(2,entry2);
+            let entry2 = searcher.database.get(2).unwrap();
+            searcher.database.put_entry(9,entry9);
+            let entry9 = searcher.database.get(9).unwrap();
+            Fixture{searcher,entry1,entry2,entry9}
+        }
+    }
+
+
+    #[wasm_bindgen_test]
+    fn loading_list() {
+        let mut test = TestWithLocalPoolExecutor::set_up();
+        let Fixture{searcher,entry1,entry9,..} = Fixture::new(|client| {
+            let completion_response = language_server::response::Completion {
+                results: vec![1,5,9],
+                current_version: default(),
+            };
+            expect_call!(client.completion(
+                module      = "Test.Test".to_string(),
+                position    = TextLocation::at_document_begin().into(),
+                self_type   = None,
+                return_type = None,
+                tag         = None
+            ) => Ok(completion_response));
+        });
 
         let mut subscriber = searcher.subscribe();
-
         searcher.reload_list();
         assert!(searcher.suggestions().is_loading());
         test.run_until_stalled();
-        let expected_list = vec![Suggestion::Completion(entry1),Suggestion::Completion(entry2)];
+        let expected_list = vec![Suggestion::Completion(entry1),Suggestion::Completion(entry9)];
         assert_eq!(searcher.suggestions().list(), Some(&expected_list));
         let notification = subscriber.next().boxed_local().expect_ready();
         assert_eq!(notification, Some(Notification::NewSuggestionList));
     }
+
+    #[wasm_bindgen_test]
+    fn parsed_input() {
+        let parser = Parser::new_or_panic();
+
+        fn args_reprs(prefix:&ast::prefix::Chain) -> Vec<String> {
+            prefix.args.iter().map(|arg| arg.repr()).collect()
+        }
+
+        let input  = "";
+        let parsed = ParsedInput::new(input.to_string(),&parser).unwrap();
+        assert!(parsed.expression.is_none());
+        assert_eq!(parsed.pattern.as_str(), "");
+
+        let input  = "foo";
+        let parsed = ParsedInput::new(input.to_string(),&parser).unwrap();
+        assert!(parsed.expression.is_none());
+        assert_eq!(parsed.pattern.as_str(), "foo");
+
+        let input  = " foo";
+        let parsed = ParsedInput::new(input.to_string(),&parser).unwrap();
+        assert!(parsed.expression.is_none());
+        assert_eq!(parsed.pattern_offset,   1);
+        assert_eq!(parsed.pattern.as_str(), "foo");
+
+        let input  = "foo  ";
+        let parsed = ParsedInput::new(input.to_string(),&parser).unwrap();
+        let expression = parsed.expression.unwrap();
+        assert_eq!(expression.off         , 0);
+        assert_eq!(expression.func.repr() , "foo");
+        assert_eq!(args_reprs(&expression) , Vec::<String>::new());
+        assert_eq!(parsed.pattern_offset,   2);
+        assert_eq!(parsed.pattern.as_str(), "");
+
+        let input  = "foo bar";
+        let parsed = ParsedInput::new(input.to_string(),&parser).unwrap();
+        let expression = parsed.expression.unwrap();
+        assert_eq!(expression.off         , 0);
+        assert_eq!(expression.func.repr() , "foo");
+        assert_eq!(args_reprs(&expression) , Vec::<String>::new());
+        assert_eq!(parsed.pattern_offset,   1);
+        assert_eq!(parsed.pattern.as_str(), "bar");
+
+        let input  = "foo  bar  baz";
+        let parsed = ParsedInput::new(input.to_string(),&parser).unwrap();
+        let expression = parsed.expression.unwrap();
+        assert_eq!(expression.off         , 0);
+        assert_eq!(expression.func.repr() , "foo");
+        assert_eq!(args_reprs(&expression) , vec!["  bar".to_string()]);
+        assert_eq!(parsed.pattern_offset  , 2);
+        assert_eq!(parsed.pattern.as_str(), "baz");
+
+        let input  = "  foo bar baz ";
+        let parsed = ParsedInput::new(input.to_string(),&parser).unwrap();
+        let expression = parsed.expression.unwrap();
+        assert_eq!(expression.off         , 2);
+        assert_eq!(expression.func.repr() , "foo");
+        assert_eq!(args_reprs(&expression) , vec![" bar".to_string()," baz".to_string()]);
+        assert_eq!(parsed.pattern_offset,   1);
+        assert_eq!(parsed.pattern.as_str(), "");
+
+        let input  = "foo bar (baz ";
+        let parsed = ParsedInput::new(input.to_string(),&parser).unwrap();
+        let expression = parsed.expression.unwrap();
+        assert_eq!(expression.off         , 0);
+        assert_eq!(expression.func.repr() , "foo");
+        assert_eq!(args_reprs(&expression) , vec![" bar".to_string()]);
+        assert_eq!(parsed.pattern_offset,   1);
+        assert_eq!(parsed.pattern.as_str(), "(baz ");
+    }
+
+    #[wasm_bindgen_test]
+    fn picked_completions_list_maintaining() {
+        let Fixture{searcher,entry1,entry2,..} = Fixture::new(|_|{});
+        let frags_borrow = || Ref::map(searcher.data.borrow(),|d| &d.fragments_added_by_picking);
+
+        // Picking first suggestion.
+        let new_input = searcher.pick_completion(entry1.clone_ref()).unwrap();
+        assert_eq!(new_input, "TestFunction1 ");
+        let (func,) = frags_borrow().iter().cloned().expect_tuple();
+        assert_eq!(func.id, CompletedFragmentId::Function);
+        assert!(Rc::ptr_eq(&func.picked_suggestion,&entry1));
+
+        // Typing more args by hand.
+        searcher.set_input("TestFunction1 some_arg pat".to_string()).unwrap();
+        let (func,) = frags_borrow().iter().cloned().expect_tuple();
+        assert_eq!(func.id, CompletedFragmentId::Function);
+        assert!(Rc::ptr_eq(&func.picked_suggestion,&entry1));
+
+        // Picking argument's suggestion.
+        let new_input = searcher.pick_completion(entry2.clone_ref()).unwrap();
+        assert_eq!(new_input, "TestFunction1 some_arg TestVar1 ");
+        let new_input = searcher.pick_completion(entry2.clone_ref()).unwrap();
+        assert_eq!(new_input, "TestFunction1 some_arg TestVar1 TestVar1 ");
+        let (function,arg1,arg2) = frags_borrow().iter().cloned().expect_tuple();
+        assert_eq!(function.id, CompletedFragmentId::Function);
+        assert!(Rc::ptr_eq(&function.picked_suggestion,&entry1));
+        assert_eq!(arg1.id, CompletedFragmentId::Argument {index:1});
+        assert!(Rc::ptr_eq(&arg1.picked_suggestion,&entry2));
+        assert_eq!(arg2.id, CompletedFragmentId::Argument {index:2});
+        assert!(Rc::ptr_eq(&arg2.picked_suggestion,&entry2));
+
+        // Backspacing back to the second arg.
+        searcher.set_input("TestFunction1 some_arg TestVar1 TestV".to_string()).unwrap();
+        let (picked,arg) = frags_borrow().iter().cloned().expect_tuple();
+        assert_eq!(picked.id, CompletedFragmentId::Function);
+        assert!(Rc::ptr_eq(&picked.picked_suggestion,&entry1));
+        assert_eq!(arg.id, CompletedFragmentId::Argument {index:1});
+        assert!(Rc::ptr_eq(&arg.picked_suggestion,&entry2));
+
+        // Editing the picked function.
+        searcher.set_input("TestFunction2 some_arg TestVar1 TestV".to_string()).unwrap();
+        let (arg,) = frags_borrow().iter().cloned().expect_tuple();
+        assert_eq!(arg.id, CompletedFragmentId::Argument {index:1});
+        assert!(Rc::ptr_eq(&arg.picked_suggestion,&entry2));
+    }
 }

gui/src/rust/ide/src/double_representation/module.rs

@@ -10,13 +10,20 @@ use ast::crumbs::ModuleCrumb;
 use ast::known;
 use ast::BlockLine;
 use enso_protocol::language_server;
-
+use data::text::ByteIndex;
 
 
 // =====================
 // === QualifiedName ===
 // =====================
 
+#[allow(missing_docs)]
+#[derive(Clone,Copy,Debug,Fail)]
+pub enum InvalidQualifiedName {
+    #[fail(display="No module segment in qualified name.")]
+    NoModuleSegment,
+}
+
 /// Module's qualified name is used in some of the Language Server's APIs, like
 /// `VisualisationConfiguration`.
 ///
@@ -25,8 +32,12 @@ use enso_protocol::language_server;
 ///
 /// See https://dev.enso.org/docs/distribution/packaging.html for more information about the
 /// package structure.
-#[derive(Clone,Debug,Display,Shrinkwrap)]
-pub struct QualifiedName(String);
+#[derive(Clone,Debug,Shrinkwrap)]
+pub struct QualifiedName {
+    #[shrinkwrap(main_field)]
+    text      : String,
+    name_part : Range<ByteIndex>,
+}
 
 impl QualifiedName {
     /// Build a module's full qualified name from its name segments and the project name.
@@ -34,21 +45,50 @@ impl QualifiedName {
     /// ```
     /// use ide::model::module::QualifiedName;
     ///
-    /// let name = QualifiedName::from_segments("Project",&["Main"]);
+    /// let name = QualifiedName::from_segments("Project",&["Main"]).unwrap();
     /// assert_eq!(name.to_string(), "Project.Main");
     /// ```
     pub fn from_segments
     (project_name:impl Str, module_segments:impl IntoIterator<Item:AsRef<str>>)
-     -> QualifiedName {
+    -> FallibleResult<QualifiedName> {
         let project_name     = std::iter::once(project_name.into());
         let module_segments  = module_segments.into_iter();
         let module_segments  = module_segments.map(|segment| segment.as_ref().to_string());
         let mut all_segments = project_name.chain(module_segments);
-        let name             = all_segments.join(".");
-        QualifiedName(name)
+        let text             = all_segments.join(ast::opr::predefined::ACCESS);
+        Ok(text.try_into()?)
+    }
+
+    /// Get the unqualified name of the module.
+    pub fn name(&self) -> &str {
+        &self.text[self.name_part.start.value..self.name_part.end.value]
     }
 }
 
+impl TryFrom<String> for QualifiedName {
+    type Error = InvalidQualifiedName;
+
+    fn try_from(text:String) -> Result<Self,Self::Error> {
+        let error      = InvalidQualifiedName::NoModuleSegment;
+        let name_start = text.rfind(ast::opr::predefined::ACCESS).ok_or(error)? + 1;
+        let name_part  = ByteIndex::new(name_start)..ByteIndex::new(text.len());
+        Ok(QualifiedName {text,name_part})
+    }
+}
+
+impl Display for QualifiedName {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&self.text,f)
+    }
+}
+
+impl PartialEq<QualifiedName> for QualifiedName {
+    fn eq(&self,rhs:&QualifiedName) -> bool {
+        self.text == rhs.text
+    }
+}
+
+impl Eq for QualifiedName {}
 
 
 // ==================
@@ -63,6 +103,8 @@ impl QualifiedName {
 #[derive(Clone,Debug,PartialEq)]
 pub struct ImportInfo {
     /// The segments of the qualified name of the imported target.
+    ///
+    /// This field is not Qualified name to cover semantically illegal imports.
     pub target:Vec<String>
 }
 
@@ -84,8 +126,8 @@ impl ImportInfo {
     }
 
     /// Obtain the qualified name of the imported module.
-    pub fn qualified_name(&self) -> QualifiedName {
-        QualifiedName(self.target.join(ast::opr::predefined::ACCESS))
+    pub fn qualified_name(&self) -> FallibleResult<QualifiedName> {
+        Ok(self.target.join(ast::opr::predefined::ACCESS).try_into()?)
     }
 
     /// Construct from an AST. Fails if the Ast is not an import declaration.
@@ -104,7 +146,8 @@ impl ImportInfo {
 
 impl Display for ImportInfo {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{} {}",ast::macros::IMPORT_KEYWORD,self.qualified_name())
+        let target = self.target.join(ast::opr::predefined::ACCESS);
+        write!(f, "{} {}",ast::macros::IMPORT_KEYWORD,target)
     }
 }
 

gui/src/rust/ide/src/model/module.rs

@@ -166,7 +166,8 @@ impl Path {
         let non_src_directories = non_src_directories.iter().map(|dirname| dirname.as_str());
         let module_name         = std::iter::once(self.module_name());
         let module_segments     = non_src_directories.chain(module_name);
-        QualifiedName::from_segments(project_name,module_segments)
+        // The module path during creation should be checked for at least one module segment.
+        QualifiedName::from_segments(project_name,module_segments).unwrap()
     }
 }
 

gui/src/rust/ide/src/model/suggestion_database.rs

@@ -2,6 +2,8 @@
 
 use crate::prelude::*;
 
+use crate::double_representation::module::QualifiedName;
+
 use enso_protocol::language_server;
 use language_server::types::SuggestionsDatabaseVersion;
 use language_server::types::SuggestionDatabaseUpdateEvent;
@@ -11,7 +13,6 @@ pub use language_server::types::SuggestionEntryId as EntryId;
 pub use language_server::types::SuggestionsDatabaseUpdate as Update;
 
 
-
 // =============
 // === Entry ===
 // =============
@@ -30,8 +31,8 @@ pub struct Entry {
     pub name : String,
     /// A type of suggestion.
     pub kind : EntryKind,
-    /// A module where the suggested object is defined.
-    pub module : String,
+    /// A module where the suggested object is defined, represented as vector of segments.
+    pub module : QualifiedName,
     /// Argument lists of suggested object (atom or function). If the object does not take any
     /// arguments, the list is empty.
     pub arguments : Vec<Argument>,
@@ -45,42 +46,63 @@ pub struct Entry {
 
 impl Entry {
     /// Create entry from the structure deserialized from the Language Server responses.
-    pub fn from_ls_entry(entry:language_server::types::SuggestionEntry) -> Self {
+    pub fn from_ls_entry(entry:language_server::types::SuggestionEntry) -> FallibleResult<Self> {
         use language_server::types::SuggestionEntry::*;
-        match entry {
+        let this = match entry {
             SuggestionEntryAtom {name,module,arguments,return_type,documentation} =>
                 Self {
-                    name,module,arguments,return_type,documentation,
-                    self_type     : None,
-                    kind          : EntryKind::Atom,
+                    name,arguments,return_type,documentation,
+                    module    : module.try_into()?,
+                    self_type : None,
+                    kind      : EntryKind::Atom,
                 },
             SuggestionEntryMethod {name,module,arguments,self_type,return_type,documentation} =>
                 Self {
-                    name,module,arguments,return_type,documentation,
-                    self_type     : Some(self_type),
-                    kind          : EntryKind::Method,
+                    name,arguments,return_type,documentation,
+                    module    : module.try_into()?,
+                    self_type : Some(self_type),
+                    kind      : EntryKind::Method,
                 },
             SuggestionEntryFunction {name,module,arguments,return_type,..} =>
                 Self {
-                    name,module,arguments,return_type,
+                    name,arguments,return_type,
+                    module        : module.try_into()?,
                     self_type     : None,
                     documentation : default(),
                     kind          : EntryKind::Function,
                 },
             SuggestionEntryLocal {name,module,return_type,..} =>
                 Self {
-                    name,module,return_type,
+                    name,return_type,
                     arguments     : default(),
+                    module        : module.try_into()?,
                     self_type     : None,
                     documentation : default(),
                     kind          : EntryKind::Local,
                 },
+        };
+        Ok(this)
+    }
+
+    /// Returns the code which should be inserted to Searcher input when suggestion is picked.
+    pub fn code_to_insert(&self) -> String {
+        let module = self.module.name();
+        if self.self_type.as_ref().contains(&module) {
+            iformat!("{module}.{self.name}")
+        } else {
+            self.name.clone()
         }
     }
+
+    /// Returns entry with the changed name.
+    pub fn with_name(self, name:impl Into<String>) -> Self {
+        Self {name:name.into(),..self}
+    }
 }
 
-impl From<language_server::types::SuggestionEntry> for Entry {
-    fn from(entry:language_server::types::SuggestionEntry) -> Self {
+impl TryFrom<language_server::types::SuggestionEntry> for Entry {
+    type Error = failure::Error;
+    fn try_from(entry:language_server::types::SuggestionEntry) -> FallibleResult<Self> {
         Self::from_ls_entry(entry)
     }
 }
@@ -99,6 +121,7 @@ impl From<language_server::types::SuggestionEntry> for Entry {
 /// argument names and types.
 #[derive(Clone,Debug,Default)]
 pub struct SuggestionDatabase {
+    logger  : Logger,
     entries : RefCell<HashMap<EntryId,Rc<Entry>>>,
     version : Cell<SuggestionsDatabaseVersion>,
 }
@@ -113,11 +136,17 @@ impl SuggestionDatabase {
 
     /// Create a new database model from response received from the Language Server.
     fn from_ls_response(response:language_server::response::GetSuggestionDatabase) -> Self {
+        let logger      = Logger::new("SuggestionDatabase");
         let mut entries = HashMap::new();
-        for entry in response.entries {
-            entries.insert(entry.id, Rc::new(Entry::from_ls_entry(entry.suggestion)));
+        for ls_entry in response.entries {
+            let id = ls_entry.id;
+            match Entry::from_ls_entry(ls_entry.suggestion) {
+                Ok(entry) => { entries.insert(id, Rc::new(entry)); },
+                Err(err)  => { error!(logger,"Discarded invalid entry {id}: {err}"); },
+            }
         }
         Self {
+            logger,
             entries : RefCell::new(entries),
             version : Cell::new(response.current_version),
         }
@@ -133,8 +162,11 @@ impl SuggestionDatabase {
         for update in event.updates {
             let mut entries = self.entries.borrow_mut();
             match update {
-                Update::Add    {id,entry} => entries.insert(id,Rc::new(entry.into())),
-                Update::Remove {id}       => entries.remove(&id),
+                Update::Add {id,entry} => match entry.try_into() {
+                    Ok(entry) => { entries.insert(id,Rc::new(entry));                       },
+                    Err(err)  => { error!(self.logger, "Discarding update for {id}: {err}") },
+                },
+                Update::Remove {id} => { entries.remove(&id); },
             };
         }
         self.version.set(event.current_version);
@@ -163,8 +195,40 @@ impl From<language_server::response::GetSuggestionDatabase> for SuggestionDataba
 #[cfg(test)]
 mod test {
     use super::*;
+
     use enso_protocol::language_server::SuggestionsDatabaseEntry;
 
+
+
+    #[test]
+    fn code_from_entry() {
+        let module = QualifiedName::from_segments("Project",&["Main"]).unwrap();
+        let atom_entry = Entry {
+            name          : "Atom".to_string(),
+            kind          : EntryKind::Atom,
+            module,
+            arguments     : vec![],
+            return_type   : "Number".to_string(),
+            documentation : None,
+            self_type     : None
+        };
+        let method_entry = Entry {
+            name      : "method".to_string(),
+            kind      : EntryKind::Method,
+            self_type : Some("Number".to_string()),
+            ..atom_entry.clone()
+        };
+        let module_method_entry = Entry {
+            name      : "moduleMethod".to_string(),
+            self_type : Some("Main".to_string()),
+            ..method_entry.clone()
+        };
+
+        assert_eq!(atom_entry.code_to_insert()         , "Atom".to_string());
+        assert_eq!(method_entry.code_to_insert()       , "method".to_string());
+        assert_eq!(module_method_entry.code_to_insert(), "Main.moduleMethod".to_string());
+    }
+
     #[test]
     fn initialize_database() {
         // Empty db
@@ -179,7 +243,7 @@ mod test {
         // Non-empty db
         let entry = language_server::types::SuggestionEntry::SuggestionEntryAtom {
             name          : "TextAtom".to_string(),
-            module        : "TestModule".to_string(),
+            module        : "TestProject.TestModule".to_string(),
             arguments     : vec![],
             return_type   : "TestAtom".to_string(),
             documentation : None
@@ -199,21 +263,21 @@ mod test {
     fn applying_update() {
         let entry1 = language_server::types::SuggestionEntry::SuggestionEntryAtom {
             name          : "Entry1".to_string(),
-            module        : "TestModule".to_string(),
+            module        : "TestProject.TestModule".to_string(),
             arguments     : vec![],
             return_type   : "TestAtom".to_string(),
             documentation : None
         };
         let entry2 = language_server::types::SuggestionEntry::SuggestionEntryAtom {
             name          : "Entry2".to_string(),
-            module        : "TestModule".to_string(),
+            module        : "TestProject.TestModule".to_string(),
             arguments     : vec![],
             return_type   : "TestAtom".to_string(),
             documentation : None
         };
         let new_entry2 = language_server::types::SuggestionEntry::SuggestionEntryAtom {
             name          : "NewEntry2".to_string(),
-            module        : "TestModule".to_string(),
+            module        : "TestProject.TestModule".to_string(),
             arguments     : vec![],
             return_type   : "TestAtom".to_string(),
             documentation : None

gui/src/rust/ide/src/view/node_editor.rs

@@ -588,7 +588,7 @@ impl GraphEditorIntegratedWithControllerModel {
         //   to the customised values.
         let project_name         = self.project.name.as_ref();
         let module_name          = crate::view::project::INITIAL_MODULE_NAME;
-        let visualisation_module = QualifiedName::from_segments(project_name,&[module_name]);
+        let visualisation_module = QualifiedName::from_segments(project_name,&[module_name])?;
         let id                   = VisualizationId::new_v4();
         let expression           = crate::constants::SERIALIZE_TO_JSON_EXPRESSION.into();
         let ast_id               = self.get_controller_node_id(*node_id)?;

gui/src/rust/lib/data/src/text.rs

@@ -41,7 +41,7 @@ impl Index {
 
 /// Strongly typed index of byte in String (which may differ with analogous character index,
 /// because some chars takes more than one byte).
-//TODO[ao] We should use structures from ensogl::,math::topology to represent different quantities
+//TODO[ao] We should use structures from ensogl::math::topology to represent different quantities
 // and units.
 #[allow(missing_docs)]
 #[derive(Clone,Copy,Debug,Default,Hash,PartialEq,Eq,PartialOrd,Ord,Serialize,Deserialize)]