Graph and Node controllers stub and mock implementations (https://github.com/enso-org/ide/pull/262)

For early design / API review.
Authored by michal.urbanczyk@luna-lang.org

Original commit: 461e6ae780

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

@@ -172,6 +172,8 @@ impl Clone for Ast {
     }
 }
 
+impl CloneRef for Ast {}
+
 /// `IntoIterator` for `&Ast` that just delegates to `&Shape`'s `IntoIterator`.
 impl<'t> IntoIterator for &'t Ast {
     type Item     = <&'t Shape<Ast> as IntoIterator>::Item;
@@ -181,6 +183,24 @@ impl<'t> IntoIterator for &'t Ast {
     }
 }
 
+impl ToString for Ast {
+    fn to_string(&self) -> String {
+        self.repr()
+    }
+}
+
+impl From<Ast> for String {
+    fn from(ast:Ast) -> Self {
+        ast.to_string()
+    }
+}
+
+impl From<&Ast> for String {
+    fn from(ast:&Ast) -> Self {
+        ast.to_string()
+    }
+}
+
 impl Ast {
     pub fn shape(&self) -> &Shape<Ast> {
         self
@@ -916,37 +936,46 @@ impl Ast {
     // TODO smart constructors for other cases
     //  as part of https://github.com/luna/enso/issues/338
 
+    /// Creates an Ast node with Number inside.
     pub fn number(number:i64) -> Ast {
         let number = Number {base:None,int:number.to_string()};
         Ast::from(number)
     }
 
-    pub fn cons<Str: ToString>(name:Str) -> Ast {
+    /// Creates an Ast node with Cons inside.
+    pub fn cons<Str:ToString>(name:Str) -> Ast {
         let cons = Cons {name:name.to_string()};
         Ast::from(cons)
     }
 
-    pub fn var<Str: ToString>(name:Str) -> Ast {
+    /// Creates an Ast node with Var inside and given ID.
+    pub fn var_with_id<Name:Str>(name:Name, id:ID) -> Ast {
+        let name = name.into();
+        let var  = Var{name};
+        Ast::new(var,Some(id))
+    }
+
+    pub fn var<Str:ToString>(name:Str) -> Ast {
         let var = Var{name:name.to_string()};
         Ast::from(var)
     }
 
-    pub fn opr<Str: ToString>(name:Str) -> Ast {
+    pub fn opr<Str:ToString>(name:Str) -> Ast {
         let opr = Opr{name:name.to_string() };
         Ast::from(opr)
     }
 
     pub fn prefix<Func:Into<Ast>, Arg:Into<Ast>>(func:Func, arg:Arg) -> Ast {
         let off = 1;
-        let opr = Prefix{ func:func.into(), off, arg:arg.into() };
+        let opr = Prefix { func:func.into(), off, arg:arg.into() };
         Ast::from(opr)
     }
 
     /// Creates an AST node with `Infix` shape, where both its operands are Vars.
-    pub fn infix_var<Str0, Str1, Str2>(larg:Str0, opr:Str1, rarg:Str2) -> Ast
+    pub fn infix_var<Str0,Str1,Str2>(larg:Str0, opr:Str1, rarg:Str2) -> Ast
-    where Str0: ToString
+    where Str0 : ToString
-        , Str1: ToString
+        , Str1 : ToString
-        , Str2: ToString {
+        , Str2 : ToString {
         let larg  = Ast::var(larg);
         let loff  = 1;
         let opr   = Ast::opr(opr);

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

@@ -15,10 +15,8 @@
 //! Controllers store their handles using `utils::cell` handle types to ensure
 //! that mutable state is safely accessed.
 
-pub mod text;
+pub mod graph;
 pub mod module;
 pub mod notification;
 pub mod project;
-
+pub mod text;
-/// General-purpose `Result` supporting any `Error`-compatible failures.
-pub type FallibleResult<T> = Result<T,failure::Error>;

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

@@ -0,0 +1,301 @@
+//! Graph Controller.
+//!
+//! This controller provides access to a specific graph. It lives under a module controller, as
+//! each graph belongs to some module.
+
+
+use crate::prelude::*;
+
+pub use crate::double_representation::graph::Id;
+
+use flo_stream::MessagePublisher;
+use flo_stream::Subscriber;
+use utils::channel::process_stream_with_handle;
+
+
+
+// ==============
+// === Errors ===
+// ==============
+
+/// Error raised when node with given Id was not found in the graph's body.
+#[derive(Clone,Copy,Debug,Fail)]
+#[fail(display="Node with Id {} was not found.", _0)]
+pub struct NodeNotFound(ast::ID);
+
+
+
+// ============
+// === Node ===
+// ============
+
+/// TODO: replace with usage of the structure to be provided by Josef
+#[derive(Clone,Copy,Debug)]
+pub struct NodeMetadata; // here goes position
+
+/// Description of the node with all information available to the graph controller.
+#[derive(Clone,Debug)]
+pub struct Node {
+    /// Information based on AST, from double_representation module.
+    pub info : double_representation::node::NodeInfo,
+    /// Information about this node stored in the module's metadata.
+    pub metadata : Option<NodeMetadata>,
+}
+
+
+
+// ===================
+// === NewNodeInfo ===
+// ===================
+
+/// Describes the node to be added.
+#[derive(Clone,Debug)]
+pub struct NewNodeInfo {
+    /// Expression to be placed on the node
+    pub expression : String,
+    /// Visual node position in the graph scene.
+    pub metadata : Option<NodeMetadata>,
+    /// ID to be given to the node.
+    pub id : Option<ast::ID>,
+    /// Where line created by adding this node should appear.
+    pub location_hint : LocationHint
+}
+
+/// Describes the desired position of the node's line in the graph's code block.
+#[derive(Clone,Copy,Debug)]
+pub enum LocationHint {
+    /// Try placing this node's line before the line described by id.
+    Before(ast::ID),
+    /// Try placing this node's line after the line described by id.
+    After(ast::ID),
+    /// Try placing this node's line at the start of the graph's code block.
+    Start,
+    /// Try placing this node's line at the end of the graph's code block.
+    End,
+}
+
+
+
+// ==================
+// === Controller ===
+// ==================
+
+/// Handle providing graph controller interface.
+#[derive(Clone,Debug)]
+pub struct Handle {
+    /// Controller of the module which this graph belongs to.
+    module    : controller::module::Handle,
+    id        : Id,
+    /// Publisher. When creating a controller, it sets up task to emit notifications through this
+    /// publisher to relay changes from the module controller.
+    // TODO: [mwu] Remove in favor of streams mapping over centralized module-scope publisher
+    publisher : Rc<RefCell<controller::notification::Publisher<controller::notification::Graph>>>,
+}
+
+impl Handle {
+    /// Gets a handle to a controller of the module that this definition belongs to.
+    pub fn module(&self) -> controller::module::Handle {
+        self.module.clone_ref()
+    }
+
+    /// Gets a handle to a controller of the module that this definition belongs to.
+    pub fn id(&self) -> Id {
+        self.id.clone()
+    }
+
+    /// Creates a new controller. Does not check if id is valid.
+    ///
+    /// Requires global executor to spawn the events relay task.
+    pub fn new_unchecked(module:controller::module::Handle, id:Id) -> Handle {
+        let graphs_notifications = module.subscribe_graph_notifications();
+        let publisher = default();
+        let ret       = Handle {module,id,publisher};
+        let weak      = Rc::downgrade(&ret.publisher);
+        let relay_notifications = process_stream_with_handle(graphs_notifications,weak,
+            |notification,this| {
+                match notification {
+                    controller::notification::Graphs::Invalidate =>
+                    this.borrow_mut().publish(controller::notification::Graph::Invalidate),
+            }
+        });
+        executor::global::spawn(relay_notifications);
+        ret
+    }
+
+    /// Creates a new graph controller. Given ID should uniquely identify a definition in the
+    /// module. Fails if ID cannot be resolved.
+    ///
+    /// Requires global executor to spawn the events relay task.
+    pub fn new(module:controller::module::Handle, id:Id) -> FallibleResult<Handle> {
+        let ret = Self::new_unchecked(module,id);
+        // Get and discard definition info, we are just making sure it can be obtained.
+        let _ = ret.graph_definition_info()?;
+        Ok(ret)
+    }
+
+    /// Retrieves double rep information about definition providing this graph.
+    pub fn graph_definition_info
+    (&self) -> FallibleResult<double_representation::definition::DefinitionInfo> {
+        let module = self.module();
+        let id     = self.id();
+        module.find_definition(&id)
+    }
+
+    /// Returns double rep information about all nodes in the graph.
+    pub fn all_node_infos
+    (&self) -> FallibleResult<Vec<double_representation::node::NodeInfo>> {
+        let definition = self.graph_definition_info()?;
+        let graph      = double_representation::graph::GraphInfo::from_definition(definition);
+        Ok(graph.nodes)
+    }
+
+    /// Retrieves double rep information about node with given ID.
+    pub fn node_info
+    (&self, id:ast::ID) -> FallibleResult<double_representation::node::NodeInfo> {
+        let nodes = self.all_node_infos()?;
+        let node  = nodes.into_iter().find(|node_info| node_info.id() == id);
+        node.ok_or_else(|| NodeNotFound(id).into())
+    }
+
+    /// Gets information about node with given id.
+    ///
+    /// Note that it is more efficient to use `get_nodes` to obtain all information at once,
+    /// rather then repeatedly call this method.
+    pub fn node(&self, id:ast::ID) -> FallibleResult<Node> {
+        let info     = self.node_info(id)?;
+        let metadata = self.node_metadata(id).ok();
+        Ok(Node {info,metadata})
+    }
+
+    /// Returns information about all the nodes currently present in this graph.
+    pub fn nodes(&self) -> FallibleResult<Vec<Node>> {
+        let node_infos = self.all_node_infos()?;
+        let mut nodes  = Vec::new();
+        for info in node_infos {
+            let metadata = self.node_metadata(info.id()).ok();
+            nodes.push(Node {info,metadata})
+        }
+        Ok(nodes)
+    }
+
+    /// Adds a new node to the graph and returns information about created node.
+    pub fn add_node(&self, _node:NewNodeInfo) -> FallibleResult<Node> {
+        todo!()
+    }
+
+    /// Removes the node with given Id.
+    pub fn remove_node(&self, _id:ast::ID) -> FallibleResult<()> {
+        todo!()
+    }
+
+    /// Subscribe to updates about changes in this graph.
+    pub fn subscribe(&self) -> Subscriber<controller::notification::Graph> {
+        self.publisher.borrow_mut().0.subscribe()
+    }
+
+    /// Retrieves metadata for the given node.
+    pub fn node_metadata(&self, _id:ast::ID) -> FallibleResult<NodeMetadata> {
+        // todo!()
+        #[derive(Clone,Copy,Debug,Display,Fail)]
+        struct NotImplemented;
+        Err(NotImplemented.into())
+    }
+
+    /// Update metadata for the given node.
+    pub fn update_node_metadata<F>(&self, _id:ast::ID, _updater:F) -> FallibleResult<NodeMetadata>
+    where F : FnOnce(&mut NodeMetadata) {
+        todo!()
+    }
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use crate::double_representation::definition::DefinitionName;
+    use crate::executor::test_utils::TestWithLocalPoolExecutor;
+    use crate::controller::module;
+    use crate::controller::notification;
+
+    use ast::HasRepr;
+    use data::text::Index;
+    use data::text::TextChange;
+    use json_rpc::test_util::transport::mock::MockTransport;
+    use parser::Parser;
+    use utils::test::ExpectTuple;
+    use wasm_bindgen_test::wasm_bindgen_test;
+
+    struct GraphControllerFixture(TestWithLocalPoolExecutor);
+    impl GraphControllerFixture {
+        pub fn set_up() -> GraphControllerFixture {
+            let nested = TestWithLocalPoolExecutor::set_up();
+            Self(nested)
+        }
+
+        pub fn run_graph_for_program<Test,Fut>(&mut self, code:impl Str, function_name:impl Str, test:Test)
+        where Test : FnOnce(module::Handle,Handle) -> Fut + 'static,
+              Fut  : Future<Output=()> {
+            let fm       = file_manager_client::Handle::new(MockTransport::new());
+            let loc      = controller::module::Location("Main".to_string());
+            let parser   = Parser::new_or_panic();
+            let module   = controller::module::Handle::new_mock(loc,code.as_ref(),default(),fm,parser).unwrap();
+            let graph_id = Id::new_single_crumb(DefinitionName::new_plain(function_name.into()));
+            let graph    = module.get_graph_controller(graph_id).unwrap();
+            self.0.run_test(async move {
+                test(module,graph).await
+            })
+        }
+
+        pub fn run_inline_graph<Test,Fut>(&mut self, definition_body:impl Str, test:Test)
+        where Test : FnOnce(module::Handle,Handle) -> Fut + 'static,
+              Fut  : Future<Output=()> {
+            assert_eq!(definition_body.as_ref().contains('\n'), false);
+            let code = format!("main = {}", definition_body.as_ref());
+            let name = "main";
+            self.run_graph_for_program(code,name,test)
+        }
+    }
+
+    #[wasm_bindgen_test]
+    fn graph_controller_notification_relay() {
+        let mut test = GraphControllerFixture::set_up();
+        test.run_graph_for_program("main = 2 + 2", "main", |module,graph| async move {
+            let text_change = TextChange::insert(Index::new(12), "2".into());
+            module.apply_code_change(&text_change).unwrap();
+
+            let mut sub = graph.subscribe();
+            module.apply_code_change(&TextChange::insert(Index::new(1),"2".to_string())).unwrap();
+            assert_eq!(Some(notification::Graph::Invalidate), sub.next().await);
+        })
+    }
+
+    #[wasm_bindgen_test]
+    fn graph_controller_inline_definition() {
+        let mut test = GraphControllerFixture::set_up();
+        const EXPRESSION: &str = "2+2";
+        test.run_inline_graph(EXPRESSION, |_,graph| async move {
+            let nodes   = graph.nodes().unwrap();
+            let (node,) = nodes.expect_tuple();
+            assert_eq!(node.info.expression().repr(), EXPRESSION);
+            let id   = node.info.id();
+            let node = graph.node(id).unwrap();
+            assert_eq!(node.info.expression().repr(), EXPRESSION);
+        })
+    }
+
+    #[wasm_bindgen_test]
+    fn graph_controller_block_definition() {
+        let mut test  = GraphControllerFixture::set_up();
+        let program = r"
+main =
+    foo = 2
+    print foo";
+        test.run_graph_for_program(program, "main", |_,graph| async move {
+            let nodes   = graph.nodes().unwrap();
+            let (node1,node2) = nodes.expect_tuple();
+            assert_eq!(node1.info.expression().repr(), "2");
+            assert_eq!(node2.info.expression().repr(), "print foo");
+        })
+    }
+}

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

@@ -7,9 +7,9 @@
 
 use crate::prelude::*;
 
-use crate::controller::FallibleResult;
 use crate::controller::notification;
 use crate::double_representation::text::apply_code_change_to_id_map;
+use crate::double_representation::definition::DefinitionInfo;
 use crate::executor::global::spawn;
 
 use parser::api::SourceFile;
@@ -17,7 +17,9 @@ use ast;
 use ast::Ast;
 use ast::HasRepr;
 use ast::IdMap;
+use ast::known;
 use data::text::*;
+use double_representation as dr;
 use file_manager_client as fmc;
 use flo_stream::MessagePublisher;
 use flo_stream::Subscriber;
@@ -108,7 +110,7 @@ shared! { Handle
         /// Publisher of "text changed" notifications
         text_notifications  : notification::Publisher<notification::Text>,
         /// Publisher of "graph changed" notifications
-        graph_notifications : notification::Publisher<notification::Graph>,
+        graph_notifications : notification::Publisher<notification::Graphs>,
         /// The logger handle.
         logger: Logger,
     }
@@ -140,6 +142,12 @@ shared! { Handle
             self.module.ast.repr()
         }
 
+        /// Obtains definition information for given graph id.
+        pub fn find_definition(&self,id:&dr::graph::Id) -> FallibleResult<DefinitionInfo> {
+            let module = known::Module::try_new(self.module.ast.clone())?;
+            double_representation::graph::traverse_for_definition(module,id)
+        }
+
         /// Check if current module state is synchronized with given code. If it's not, log error,
         /// and update module state to match the `code` passed as argument.
         pub fn check_code_sync(&mut self, code:String) -> FallibleResult<()> {
@@ -159,7 +167,7 @@ shared! { Handle
         }
 
         /// Get subscriber receiving notifications about changes in module's graph representation.
-        pub fn subscribe_graph_notifications(&mut self) -> Subscriber<notification::Graph> {
+        pub fn subscribe_graph_notifications(&mut self) -> Subscriber<notification::Graphs> {
             self.graph_notifications.subscribe()
         }
     }
@@ -178,8 +186,9 @@ impl Handle {
         let text_notifications  = default();
         let graph_notifications = default();
 
-        let data = Controller {location,module,file_manager,parser,id_map,logger,text_notifications,
+
-            graph_notifications};
+        let data = Controller {location,module,file_manager,parser,id_map,logger,
+            text_notifications,graph_notifications};
         let handle = Handle::new_from_data(data);
         handle.load_file().await?;
         Ok(handle)
@@ -216,6 +225,13 @@ impl Handle {
         async move { fm.write(path.clone(),code?).await }
     }
 
+    /// Returns a graph controller for graph in this module's subtree identified by `id`.
+    /// Reuses already existing controller if possible.
+    pub fn get_graph_controller(&self, id:dr::graph::Id)
+    -> FallibleResult<controller::graph::Handle> {
+        controller::graph::Handle::new(self.clone(),id)
+    }
+
     #[cfg(test)]
     pub fn new_mock
     ( location     : Location
@@ -240,7 +256,7 @@ impl Controller {
     fn update_ast(&mut self,ast:Ast) {
         self.module.ast  = ast;
         let text_change  = notification::Text::Invalidate;
-        let graph_change = notification::Graph::Invalidate;
+        let graph_change = notification::Graphs::Invalidate;
         let code_notify  = self.text_notifications.publish(text_change);
         let graph_notify = self.graph_notifications.publish(graph_change);
         spawn(async move { futures::join!(code_notify,graph_notify); });
@@ -248,6 +264,10 @@ impl Controller {
 }
 
 
+// =============
+// === Tests ===
+// =============
+
 #[cfg(test)]
 mod test {
     use super::*;
@@ -318,7 +338,7 @@ mod test {
 
             // Check emitted notifications
             assert_eq!(Some(notification::Text::Invalidate ), text_notifications.next().await );
-            assert_eq!(Some(notification::Graph::Invalidate), graph_notifications.next().await);
+            assert_eq!(Some(notification::Graphs::Invalidate), graph_notifications.next().await);
         });
     }
 }

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

@@ -16,7 +16,6 @@ use crate::prelude::*;
 /// therefore there is no need for setting big buffers.
 const NOTIFICATION_BUFFER_SIZE : usize = 36;
 
-
 /// A notification publisher which implements Debug and Default.
 #[derive(Shrinkwrap)]
 #[shrinkwrap(mutable)]
@@ -36,7 +35,6 @@ impl<Message:'static> Debug for Publisher<Message> {
 
 
 
-
 // =====================================
 // === Double Representation Changes ===
 // =====================================
@@ -51,11 +49,33 @@ pub enum Text {
 }
 
 
-// === Graph ===
+// === Graphs ===
 
 /// A notification about changes of graph representation of a module.
 #[derive(Copy,Clone,Debug,Eq,PartialEq)]
+pub enum Graphs {
+    /// The content should be fully reloaded.
+    Invalidate,
+}
+
+
+// === Graph ===
+
+/// A notification about changes of a specific graph in a module.
+#[derive(Copy,Clone,Debug,Eq,PartialEq)]
 pub enum Graph {
     /// The content should be fully reloaded.
     Invalidate,
 }
+
+
+// === Node ===
+
+/// A notification about changes of specific node in a graph.
+#[derive(Copy,Clone,Debug,Eq,PartialEq)]
+pub enum Node {
+    /// The content should be fully reloaded.
+    Invalidate,
+}
+
+

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

@@ -5,8 +5,6 @@
 
 use crate::prelude::*;
 
-use crate::controller::FallibleResult;
-
 use file_manager_client as fmc;
 use json_rpc::Transport;
 use parser::Parser;

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

@@ -5,7 +5,6 @@
 //! user.
 
 use crate::prelude::*;
-use crate::controller::FallibleResult;
 use crate::controller::notification;
 use crate::executor::global::spawn;
 

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

@@ -8,7 +8,7 @@ use ast::Shape;
 use ast::known;
 use ast::prefix;
 use ast::opr;
-
+use shapely::EmptyIterator;
 
 
 // =================
@@ -93,16 +93,16 @@ impl DefinitionName {
     }
 }
 
-impl ToString for DefinitionName {
+impl Display for DefinitionName {
-    fn to_string(&self) -> String {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let mut pieces = self.extended_target.iter().map(|s| s.as_str()).collect_vec();
         pieces.push(&self.name);
-        pieces.join(opr::predefined::ACCESS)
+        let text = pieces.join(opr::predefined::ACCESS);
+        write!(f, "{}", text)
     }
 }
 
 
-
 // ======================
 // === DefinitionInfo ===
 // ======================
@@ -216,6 +216,16 @@ impl DefinitionProvider for known::Block {
     }
 }
 
+impl DefinitionProvider for DefinitionInfo {
+    fn scope_kind() -> ScopeKind { ScopeKind::NonRoot }
+    fn line_asts<'a>(&'a self) -> Box<dyn Iterator<Item=&'a Ast> + 'a> {
+        match self.ast.rarg.shape() {
+            ast::Shape::Block(_) => self.ast.rarg.iter(),
+            _                    => Box::new(EmptyIterator::new())
+        }
+    }
+}
+
 
 
 // =============

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

@@ -3,6 +3,9 @@
 use crate::prelude::*;
 
 use crate::double_representation::definition;
+use crate::double_representation::definition::DefinitionInfo;
+use crate::double_representation::definition::DefinitionName;
+use crate::double_representation::definition::DefinitionProvider;
 use crate::double_representation::node;
 
 use ast::Ast;
@@ -10,6 +13,59 @@ use ast::known;
 
 
 
+// ================
+// === Graph Id ===
+// ================
+
+/// Crumb describes step that needs to be done when going from context (for graph being a module)
+/// to the target.
+// TODO [mwu]
+//  Currently we support only entering named definitions.
+pub type Crumb = DefinitionName;
+
+/// Identifies graph in the module.
+#[derive(Clone,Debug,Eq,Hash,PartialEq)]
+pub struct Id {
+    /// Sequence of traverses from module root up to the identified graph.
+    pub crumbs : Vec<Crumb>,
+}
+
+impl Id {
+    /// Creates a new graph identifier consisting of a single crumb.
+    pub fn new_single_crumb(crumb:DefinitionName) -> Id {
+        let crumbs = vec![crumb];
+        Id {crumbs}
+    }
+}
+
+
+// ===============================
+// === Finding Graph In Module ===
+// ===============================
+
+#[derive(Fail,Clone,Debug)]
+#[fail(display="Definition ID was empty")]
+struct CannotFindDefinition(Id);
+
+#[derive(Fail,Clone,Debug)]
+#[fail(display="Definition ID was empty")]
+struct EmptyDefinitionId;
+
+/// Looks up graph in the module.
+pub fn traverse_for_definition
+(ast:ast::known::Module, id:&Id) -> FallibleResult<DefinitionInfo> {
+    let err            = || CannotFindDefinition(id.clone());
+    let mut crumb_iter = id.crumbs.iter();
+    let first_crumb    = crumb_iter.next().ok_or(EmptyDefinitionId)?;
+    let mut definition = ast.find_definition(first_crumb).ok_or_else(err)?;
+    for crumb in crumb_iter {
+        definition = definition.find_definition(crumb).ok_or_else(err)?;
+    }
+    Ok(definition)
+}
+
+
+
 // =================
 // === GraphInfo ===
 // =================
@@ -17,20 +73,17 @@ use ast::known;
 /// Description of the graph, based on information available in AST.
 #[derive(Clone,Debug)]
 pub struct GraphInfo {
-    name : definition::DefinitionName,
+    source : DefinitionInfo,
-    args : Vec<Ast>,
     /// Describes all known nodes in this graph (does not include special pseudo-nodes like graph
     /// inputs and outputs).
-    pub nodes:Vec<node::NodeInfo>,
+    pub nodes : Vec<node::NodeInfo>,
 }
 
 impl GraphInfo {
     /// Describe graph of the given definition.
-    pub fn from_definition(info:&definition::DefinitionInfo) -> GraphInfo {
+    pub fn from_definition(source:DefinitionInfo) -> GraphInfo {
-        let name  = info.name.clone();
+        let nodes = Self::from_function_binding(source.ast.clone());
-        let args  = info.args.clone();
+        GraphInfo {source,nodes}
-        let nodes = Self::from_function_binding(info.ast.clone());
-        GraphInfo {name,args,nodes}
     }
 
     /// Lists nodes in the given binding's ast (infix expression).
@@ -79,6 +132,7 @@ mod tests {
     use crate::double_representation::definition::DefinitionName;
     use crate::double_representation::definition::DefinitionProvider;
 
+    use ast::HasRepr;
     use parser::api::IsParser;
     use wasm_bindgen_test::wasm_bindgen_test;
 
@@ -89,8 +143,7 @@ mod tests {
         let module = parser.parse_module(program.into(), default()).unwrap();
         let name   = DefinitionName::new_plain("main");
         let main   = module.find_definition(&name).unwrap();
-        println!("{:?}",module);
+        GraphInfo::from_definition(main)
-        GraphInfo::from_definition(&main)
     }
 
     #[wasm_bindgen_test]
@@ -107,7 +160,7 @@ mod tests {
             let graph = main_graph(&mut parser, program);
             assert_eq!(graph.nodes.len(), 1);
             let node = &graph.nodes[0];
-            assert_eq!(node.expression_text(), "2+2");
+            assert_eq!(node.expression().repr(), "2+2");
             let _ = node.id(); // just to make sure it is available
         }
     }
@@ -119,15 +172,13 @@ mod tests {
 main =
     foo = node
     foo a = not_node
+    Int.= a = node
     node
 ";
-        // TODO [mwu]
-        //  Add case like `Int.= a = node` once https://github.com/luna/enso/issues/565 is fixed
-
         let graph = main_graph(&mut parser, program);
         assert_eq!(graph.nodes.len(), 2);
         for node in graph.nodes.iter() {
-            assert_eq!(node.expression_text(), "node");
+            assert_eq!(node.expression().repr(), "node");
         }
     }
-}
+}

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

@@ -1,7 +1,6 @@
 //! Code for node discovery and other node-related tasks.
 
 use ast::Ast;
-use ast::HasRepr;
 use ast::ID;
 use ast::known;
 
@@ -47,23 +46,18 @@ impl NodeInfo {
 
     /// Node's unique ID.
     pub fn id(&self) -> ID {
-        // Panic must not happen, as the only available constructor checks that
+        // Panic must not happen, as the only available constructors checks that
         // there is an ID present.
-        self.expression_ast().id.expect("Node AST must bear an ID")
+        self.expression().id.expect("Node AST must bear an ID")
     }
 
     /// AST of the node's expression.
-    pub fn expression_ast(&self) -> &Ast {
+    pub fn expression(&self) -> &Ast {
         match self {
             NodeInfo::Binding   {infix} => &infix.rarg,
             NodeInfo::Expression{ast}   => &ast,
         }
     }
-
-    /// The node's expression textual representation.
-    pub fn expression_text(&self) -> String {
-        self.expression_ast().repr()
-    }
 }
 
 
@@ -76,13 +70,14 @@ impl NodeInfo {
 mod tests {
     use super::*;
 
+    use ast::HasRepr;
     use wasm_bindgen_test::wasm_bindgen_test;
 
     wasm_bindgen_test::wasm_bindgen_test_configure!(run_in_browser);
 
     fn expect_node(ast:Ast, expression_text:&str, id:ID) {
         let node_info = NodeInfo::from_line_ast(&ast).expect("expected a node");
-        assert_eq!(node_info.expression_text(),expression_text);
+        assert_eq!(node_info.expression().repr(),expression_text);
         assert_eq!(node_info.id(), id);
     }
 

gui/src/rust/ide/src/lib.rs

@@ -35,6 +35,8 @@ pub mod prelude {
     pub use futures::Stream;
     pub use futures::StreamExt;
     pub use futures::task::LocalSpawnExt;
+
+    pub use utils::fail::FallibleResult;
 }
 
 use crate::prelude::*;

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

@@ -4,7 +4,6 @@
 use crate::prelude::*;
 
 use crate::view::layout::ViewLayout;
-use crate::controller::FallibleResult;
 
 use ensogl::control::callback::CallbackHandle;
 use ensogl::control::io::keyboard::listener::KeyboardFrpBindings;

gui/src/rust/ide/utils/src/fail.rs

@@ -0,0 +1,4 @@
+//! General-purpose code related to error handling.
+
+/// General-purpose `Result` supporting any `Error`-compatible failures.
+pub type FallibleResult<T> = Result<T,failure::Error>;

gui/src/rust/ide/utils/src/lib.rs

@@ -14,4 +14,5 @@ pub use enso_prelude as prelude;
 
 pub mod channel;
 pub mod env;
+pub mod fail;
 pub mod test;