[ty] Refactor inlay hints structure to use separate parts (#20052)

## Summary

Our internal inlay hints structure (`ty_ide::InlayHint`) now more
closely resembles `lsp_types::InlayHint`.

This mainly allows us to convert to `lsp_types::InlayHint` with less
hassle, but it also allows us to manage the different parts of the inlay
hint better, which in the future will allow us to implement features
like goto on the type part of the type inlay hint.

It also really isn't important to store a specific `Type` instance in
the `InlayHintContent`. So we remove this and use `InlayHintLabel`
instead which just shows the representation of the type (along with
other information).

We see a similar structure used in rust-analyzer too.

crates/ty_ide/src/inlay_hints.rs

@@ -1,62 +1,128 @@
+use std::{fmt, vec};
+
 use crate::Db;
 use ruff_db::files::File;
 use ruff_db::parsed::parsed_module;
 use ruff_python_ast::visitor::source_order::{self, SourceOrderVisitor, TraversalSignal};
 use ruff_python_ast::{AnyNodeRef, Expr, Stmt};
 use ruff_text_size::{Ranged, TextRange, TextSize};
-use std::fmt;
-use std::fmt::Formatter;
 use ty_python_semantic::types::{Type, inlay_hint_function_argument_details};
 use ty_python_semantic::{HasType, SemanticModel};
 
-#[derive(Debug, Clone, Eq, PartialEq)]
-pub struct InlayHint<'db> {
+#[derive(Debug, Clone)]
+pub struct InlayHint {
     pub position: TextSize,
-    pub content: InlayHintContent<'db>,
+    pub kind: InlayHintKind,
+    pub label: InlayHintLabel,
 }
 
-impl<'db> InlayHint<'db> {
-    pub const fn display(&self, db: &'db dyn Db) -> DisplayInlayHint<'_, 'db> {
-        self.content.display(db)
+impl InlayHint {
+    fn variable_type(position: TextSize, ty: Type, db: &dyn Db) -> Self {
+        let label_parts = vec![
+            ": ".into(),
+            InlayHintLabelPart::new(ty.display(db).to_string()),
+        ];
+
+        Self {
+            position,
+            kind: InlayHintKind::Type,
+            label: InlayHintLabel { parts: label_parts },
         }
     }
 
-#[derive(Debug, Clone, Eq, PartialEq)]
-pub enum InlayHintContent<'db> {
-    Type(Type<'db>),
-    CallArgumentName(String),
-}
+    fn call_argument_name(position: TextSize, name: &str) -> Self {
+        let label_parts = vec![InlayHintLabelPart::new(name), "=".into()];
 
-impl<'db> InlayHintContent<'db> {
-    pub const fn display(&self, db: &'db dyn Db) -> DisplayInlayHint<'_, 'db> {
-        DisplayInlayHint { db, hint: self }
+        Self {
+            position,
+            kind: InlayHintKind::CallArgumentName,
+            label: InlayHintLabel { parts: label_parts },
         }
     }
 
-pub struct DisplayInlayHint<'a, 'db> {
-    db: &'db dyn Db,
-    hint: &'a InlayHintContent<'db>,
+    pub fn display(&self) -> InlayHintDisplay<'_> {
+        InlayHintDisplay { inlay_hint: self }
+    }
 }
 
-impl fmt::Display for DisplayInlayHint<'_, '_> {
-    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
-        match self.hint {
-            InlayHintContent::Type(ty) => {
-                write!(f, ": {}", ty.display(self.db))
+#[derive(Debug, Clone)]
+pub enum InlayHintKind {
+    Type,
+    CallArgumentName,
 }
-            InlayHintContent::CallArgumentName(name) => {
-                write!(f, "{name}=")
+
+#[derive(Debug, Clone)]
+pub struct InlayHintLabel {
+    parts: Vec<InlayHintLabelPart>,
 }
+
+impl InlayHintLabel {
+    pub fn parts(&self) -> &[InlayHintLabelPart] {
+        &self.parts
+    }
+}
+
+pub struct InlayHintDisplay<'a> {
+    inlay_hint: &'a InlayHint,
+}
+
+impl fmt::Display for InlayHintDisplay<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> std::fmt::Result {
+        for part in &self.inlay_hint.label.parts {
+            write!(f, "{}", part.text)?;
+        }
+        Ok(())
+    }
+}
+
+#[derive(Default, Debug, Clone)]
+pub struct InlayHintLabelPart {
+    text: String,
+
+    target: Option<crate::NavigationTarget>,
+}
+
+impl InlayHintLabelPart {
+    pub fn new(text: impl Into<String>) -> Self {
+        Self {
+            text: text.into(),
+            target: None,
+        }
+    }
+
+    pub fn text(&self) -> &str {
+        &self.text
+    }
+
+    pub fn target(&self) -> Option<&crate::NavigationTarget> {
+        self.target.as_ref()
+    }
+}
+
+impl From<String> for InlayHintLabelPart {
+    fn from(s: String) -> Self {
+        Self {
+            text: s,
+            target: None,
         }
     }
 }
 
-pub fn inlay_hints<'db>(
-    db: &'db dyn Db,
+impl From<&str> for InlayHintLabelPart {
+    fn from(s: &str) -> Self {
+        Self {
+            text: s.to_string(),
+            target: None,
+        }
+    }
+}
+
+pub fn inlay_hints(
+    db: &dyn Db,
     file: File,
     range: TextRange,
     settings: &InlayHintSettings,
-) -> Vec<InlayHint<'db>> {
+) -> Vec<InlayHint> {
     let mut visitor = InlayHintVisitor::new(db, file, range, settings);
 
     let ast = parsed_module(db, file).load(db);
@@ -106,7 +172,7 @@ impl Default for InlayHintSettings {
 struct InlayHintVisitor<'a, 'db> {
     db: &'db dyn Db,
     model: SemanticModel<'db>,
-    hints: Vec<InlayHint<'db>>,
+    hints: Vec<InlayHint>,
     in_assignment: bool,
     range: TextRange,
     settings: &'a InlayHintSettings,
@@ -128,13 +194,11 @@ impl<'a, 'db> InlayHintVisitor<'a, 'db> {
         if !self.settings.variable_types {
             return;
         }
-        self.hints.push(InlayHint {
-            position,
-            content: InlayHintContent::Type(ty),
-        });
+        self.hints
+            .push(InlayHint::variable_type(position, ty, self.db));
     }
 
-    fn add_call_argument_name(&mut self, position: TextSize, name: String) {
+    fn add_call_argument_name(&mut self, position: TextSize, name: &str) {
         if !self.settings.call_argument_names {
             return;
         }
@@ -143,10 +207,8 @@ impl<'a, 'db> InlayHintVisitor<'a, 'db> {
             return;
         }
 
-        self.hints.push(InlayHint {
-            position,
-            content: InlayHintContent::CallArgumentName(name),
-        });
+        self.hints
+            .push(InlayHint::call_argument_name(position, name));
     }
 }
 
@@ -212,10 +274,7 @@ impl SourceOrderVisitor<'_> for InlayHintVisitor<'_, '_> {
 
                 for (index, arg_or_keyword) in call.arguments.arguments_source_order().enumerate() {
                     if let Some(name) = argument_names.get(&index) {
-                        self.add_call_argument_name(
-                            arg_or_keyword.range().start(),
-                            name.to_string(),
-                        );
+                        self.add_call_argument_name(arg_or_keyword.range().start(), name);
                     }
                     self.visit_expr(arg_or_keyword.value());
                 }
@@ -322,7 +381,7 @@ mod tests {
 
             for hint in hints {
                 let end_position = (hint.position.to_u32() as usize) + offset;
-                let hint_str = format!("[{}]", hint.display(&self.db));
+                let hint_str = format!("[{}]", hint.display());
                 buf.insert_str(end_position, &hint_str);
                 offset += hint_str.len();
             }

crates/ty_ide/src/lib.rs

@@ -30,7 +30,7 @@ pub use document_symbols::document_symbols;
 pub use goto::{goto_declaration, goto_definition, goto_type_definition};
 pub use goto_references::goto_references;
 pub use hover::hover;
-pub use inlay_hints::{InlayHintContent, InlayHintSettings, inlay_hints};
+pub use inlay_hints::{InlayHintKind, InlayHintLabel, InlayHintSettings, inlay_hints};
 pub use markup::MarkupKind;
 pub use references::ReferencesMode;
 pub use rename::{can_rename, rename};

crates/ty_server/src/server/api/requests/inlay_hints.rs

@@ -9,7 +9,7 @@ use crate::session::client::Client;
 use lsp_types::request::InlayHintRequest;
 use lsp_types::{InlayHintParams, Url};
 use ruff_db::source::{line_index, source_text};
-use ty_ide::{InlayHintContent, inlay_hints};
+use ty_ide::{InlayHintKind, InlayHintLabel, inlay_hints};
 use ty_project::ProjectDatabase;
 
 pub(crate) struct InlayHintRequestHandler;
@@ -55,8 +55,8 @@ impl BackgroundDocumentRequestHandler for InlayHintRequestHandler {
                 position: hint
                     .position
                     .to_position(&source, &index, snapshot.encoding()),
-                label: lsp_types::InlayHintLabel::String(hint.display(db).to_string()),
-                kind: Some(inlay_hint_kind(&hint.content)),
+                label: inlay_hint_label(&hint.label),
+                kind: Some(inlay_hint_kind(&hint.kind)),
                 tooltip: None,
                 padding_left: None,
                 padding_right: None,
@@ -71,9 +71,22 @@ impl BackgroundDocumentRequestHandler for InlayHintRequestHandler {
 
 impl RetriableRequestHandler for InlayHintRequestHandler {}
 
-fn inlay_hint_kind(inlay_hint_content: &InlayHintContent) -> lsp_types::InlayHintKind {
-    match inlay_hint_content {
-        InlayHintContent::Type(_) => lsp_types::InlayHintKind::TYPE,
-        InlayHintContent::CallArgumentName(_) => lsp_types::InlayHintKind::PARAMETER,
+fn inlay_hint_kind(inlay_hint_kind: &InlayHintKind) -> lsp_types::InlayHintKind {
+    match inlay_hint_kind {
+        InlayHintKind::Type => lsp_types::InlayHintKind::TYPE,
+        InlayHintKind::CallArgumentName => lsp_types::InlayHintKind::PARAMETER,
     }
 }
+
+fn inlay_hint_label(inlay_hint_label: &InlayHintLabel) -> lsp_types::InlayHintLabel {
+    let mut label_parts = Vec::new();
+    for part in inlay_hint_label.parts() {
+        label_parts.push(lsp_types::InlayHintLabelPart {
+            value: part.text().into(),
+            location: None,
+            tooltip: None,
+            command: None,
+        });
+    }
+    lsp_types::InlayHintLabel::LabelParts(label_parts)
+}

crates/ty_server/tests/e2e/inlay_hints.rs

@@ -42,7 +42,14 @@ foo(1)
           "line": 0,
           "character": 1
         },
-        "label": ": Literal[1]",
+        "label": [
+          {
+            "value": ": "
+          },
+          {
+            "value": "Literal[1]"
+          }
+        ],
         "kind": 1
       },
       {
@@ -50,7 +57,14 @@ foo(1)
           "line": 5,
           "character": 4
         },
-        "label": "a=",
+        "label": [
+          {
+            "value": "a"
+          },
+          {
+            "value": "="
+          }
+        ],
         "kind": 2
       }
     ]

crates/ty_wasm/src/lib.rs

@@ -449,14 +449,14 @@ impl Workspace {
         Ok(result
             .into_iter()
             .map(|hint| InlayHint {
-                markdown: hint.display(&self.db).to_string(),
+                markdown: hint.display().to_string(),
                 position: Position::from_text_size(
                     hint.position,
                     &index,
                     &source,
                     self.position_encoding,
                 ),
-                kind: hint.content.into(),
+                kind: hint.kind.into(),
             })
             .collect())
     }
@@ -988,11 +988,11 @@ pub enum InlayHintKind {
     Parameter,
 }
 
-impl From<ty_ide::InlayHintContent<'_>> for InlayHintKind {
-    fn from(kind: ty_ide::InlayHintContent) -> Self {
+impl From<ty_ide::InlayHintKind> for InlayHintKind {
+    fn from(kind: ty_ide::InlayHintKind) -> Self {
         match kind {
-            ty_ide::InlayHintContent::Type(_) => Self::Type,
-            ty_ide::InlayHintContent::CallArgumentName(_) => Self::Parameter,
+            ty_ide::InlayHintKind::Type => Self::Type,
+            ty_ide::InlayHintKind::CallArgumentName => Self::Parameter,
         }
     }
 }