Show default per-kind icons for all entries in Component Browser. (#3587)

Show default icons for all entries in the Component Browser. The icons are assigned to each entry depending on its kind.

https://www.pivotaltracker.com/story/show/182584326

#### Visuals

See below for a video showing entries of 5 different kinds in the Component Browser, each having a different icon. When watching the video, please note that the following are preexisting, known issues, not introduced by this PR:
- Selection is misaligned when hovering the mouse over the "new" component in the "Mcdbg Group 1" group - reported as issue 2 [in comments to PR 3530](https://github.com/enso-org/enso/pull/3530#pullrequestreview-1034223437).
- [Names of Modules and Atoms displayed in Component Browser start with a small letter.](https://www.pivotaltracker.com/story/show/182745386)




https://user-images.githubusercontent.com/273837/179016109-c3ebab5a-0205-4b44-85b8-df3129edd75d.mov

# Important Notes
- A new derive macro `ForEachVariant` is defined and added to the `enso-prelude` crate.

app/gui/src/model/suggestion_database/entry.rs

@@ -132,7 +132,7 @@ impl<'a> IntoIterator for &'a QualifiedName {
 // =============
 
 /// A type of suggestion entry.
-#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+#[derive(Copy, Clone, Debug, Eq, PartialEq, ForEachVariant)]
 #[allow(missing_docs)]
 pub enum Kind {
     Atom,

app/gui/src/presenter/searcher/provider.rs

@@ -157,6 +157,12 @@ impl ide_view::searcher::DocumentationProvider for Action {
     }
 }
 
+
+
+// ===========================
+// === provider::Component ===
+// ===========================
+
 /// Component Provider getting entries from a [`controller::searcher::component::Group`].
 #[derive(Clone, CloneRef, Debug)]
 pub struct Component {
@@ -170,23 +176,40 @@ impl Component {
     }
 }
 
+macro_rules! kind_to_icon {
+    ([ $( $variant:ident ),* ] $kind:ident) => {
+        {
+            use component_group_view::icon::Id;
+            use suggestion_database::entry::Kind;
+            match $kind {
+                $( Kind::$variant => Id::$variant, )*
+            }
+        }
+    }
+}
+
 impl list_view::entry::ModelProvider<component_group_view::Entry> for Component {
     fn entry_count(&self) -> usize {
         self.group.matched_items.get()
     }
 
     fn get(&self, id: usize) -> Option<component_group_view::entry::Model> {
+        use suggestion_database::entry::for_each_kind_variant;
         let component = self.group.get_entry(id)?;
         let match_info = component.match_info.borrow();
         let label = component.label();
         let highlighted = bytes_of_matched_letters(&*match_info, &label);
+        let kind = component.suggestion.kind;
         Some(component_group_view::entry::Model {
-            icon:             component_group_view::icon::Id::AddColumn,
+            icon:             for_each_kind_variant!(kind_to_icon(kind)),
             highlighted_text: list_view::entry::GlyphHighlightedLabelModel { label, highlighted },
         })
     }
 }
 
+
+// === Component Provider helpers ===
+
 fn bytes_of_matched_letters(match_info: &MatchInfo, label: &str) -> Vec<text::Range<text::Bytes>> {
     if let MatchInfo::Matches { subsequence } = match_info {
         let mut char_iter = label.char_indices().enumerate();
@@ -211,6 +234,12 @@ fn bytes_of_matched_letters(match_info: &MatchInfo, label: &str) -> Vec<text::Ra
     }
 }
 
+
+
+// ===========================
+// === Converter functions ===
+// ===========================
+
 /// Get [`LabeledAnyModelProvider`] for given component group.
 pub fn from_component_group(
     group: &controller::searcher::component::Group,

lib/rust/prelude/src/macros.rs

@@ -1,4 +1,11 @@
-//! This macro defines set of common macros which are useful across different projects.
+//! This module defines set of common macros which are useful across different projects.
+
+
+// ==============
+// === Export ===
+// ==============
+
+pub use enso_shapely::ForEachVariant;
 
 
 

lib/rust/shapely/macros/src/derive_for_each_variant.rs

@@ -0,0 +1,44 @@
+//! This module contains the [`derive`] function (implementing the [`crate::ForEachVariant`] derive
+//! macro) as well as its helper functions.
+
+use inflector::cases::snakecase::to_snake_case;
+use proc_macro2::TokenStream;
+use quote::quote;
+use syn::punctuated::Punctuated;
+use syn::Token;
+
+
+
+// ======================
+// === ForEachVariant ===
+// ======================
+
+/// Implementation of the `ForEachVariant` derive macro. For details, see the documentation of the
+/// [`crate::derive_for_each_variant`] function.
+pub fn derive(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    let decl = syn::parse_macro_input!(input as syn::DeriveInput);
+    let ret = match decl.data {
+        syn::Data::Enum(ref e) => derive_for_enum(&decl, e),
+        _ => panic!("The `ForEachVariant` derive macro only works on enums."),
+    };
+    proc_macro::TokenStream::from(ret)
+}
+
+fn derive_for_enum(decl: &syn::DeriveInput, data: &syn::DataEnum) -> TokenStream {
+    let enum_name = &decl.ident;
+    let enum_snake_name = to_snake_case(&enum_name.to_string());
+    let macro_name = quote::format_ident!("for_each_{}_variant", enum_snake_name);
+    let variant_names: Punctuated<_, Token![,]> = data.variants.iter().map(|v| &v.ident).collect();
+    quote! {
+        /// Calls `f!` passing to it a comma-separated list of names of variants of [`#enum_name`]
+        /// enclosed in square brackets. The extra `args` are passed to `f!` verbatim after the
+        /// closing square bracket. For more details, see the documentation of the
+        /// [`ForEachVariant`] derive macro.
+        #[macro_export]
+        macro_rules! #macro_name {
+            ( $f:ident($( $args:tt )*) ) => { $f!([ #variant_names ] $($args)*) }
+        }
+
+        pub(crate) use #macro_name;
+    }
+}

lib/rust/shapely/macros/src/lib.rs

@@ -23,6 +23,7 @@ extern crate proc_macro;
 
 mod derive_clone_ref;
 mod derive_entry_point;
+mod derive_for_each_variant;
 mod derive_iterator;
 mod derive_no_clone;
 mod overlappable;
@@ -114,6 +115,38 @@ pub fn derive_no_clone(input: proc_macro::TokenStream) -> proc_macro::TokenStrea
     derive_no_clone::derive(input)
 }
 
+/// Implements the `ForEachVariant` derive macro which creates a helper for iterating over each
+/// variant of an enum at compile time. The derive panics if used on non-enum types.
+///
+/// The derive creates a macro (hereafter called loop-macro) named `for_each_NAME_variant` where
+/// `NAME` is replaced with the name of the enum converted to snake case. The loop-macro takes a
+/// name of another macro (hereafter called iterator-macro) as an argument followed by a
+/// parenthesized list of extra arguments. The loop-macro expands to a call of the iterator-macro
+/// with a list of comma-separated names of the enum variants wrapped in square brackets, followed
+/// by the extra arguments defined above.
+///
+/// For example, the following code:
+/// ```no_compile
+/// #[derive(ForEachVariant)]
+/// pub enum FooBar {
+///     Foo,
+///     Bar,
+/// }
+/// ```
+/// results in the following macro being defined:
+/// ```
+/// #[macro_export]
+/// macro_rules! for_each_foo_bar_variant {
+///     ( $f:ident($( $args:tt )*) ) => { $f!([Foo, Bar] $($args)*) }
+/// }
+///
+/// pub(crate) use for_each_foo_bar_variant;
+/// ```
+#[proc_macro_derive(ForEachVariant)]
+pub fn derive_for_each_variant(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    derive_for_each_variant::derive(input)
+}
+
 /// Exposes the function as an application entry point. Entry points are alternative application
 /// running modes that you can access by adding `?entry=` to the end of the application URL.
 #[proc_macro_attribute]