Refactor server api

crates/ra_ide_api/src/inlay_hints.rs

@@ -0,0 +1,110 @@
+use ra_syntax::{
+    algo::visit::{visitor, Visitor},
+    ast::{self, PatKind, TypeAscriptionOwner},
+    AstNode, SmolStr, SourceFile, SyntaxNode, TextRange,
+};
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum InlayKind {
+    LetBinding,
+    ClosureParameter,
+}
+
+#[derive(Debug)]
+pub struct InlayHint {
+    pub range: TextRange,
+    pub text: SmolStr,
+    pub inlay_kind: InlayKind,
+}
+
+pub(crate) fn inlay_hints(file: &SourceFile) -> Vec<InlayHint> {
+    file.syntax().descendants().map(|node| get_inlay_hints(&node)).flatten().collect()
+}
+
+fn get_inlay_hints(node: &SyntaxNode) -> Vec<InlayHint> {
+    visitor()
+        .visit(|let_statement: ast::LetStmt| {
+            let let_syntax = let_statement.syntax();
+
+            if let_statement.ascribed_type().is_some() {
+                return Vec::new();
+            }
+
+            let pat_range = match let_statement.pat().map(|pat| pat.kind()) {
+                Some(PatKind::BindPat(bind_pat)) => bind_pat.syntax().text_range(),
+                Some(PatKind::TuplePat(tuple_pat)) => tuple_pat.syntax().text_range(),
+                _ => return Vec::new(),
+            };
+
+            vec![InlayHint {
+                range: pat_range,
+                text: let_syntax.text().to_smol_string(),
+                inlay_kind: InlayKind::LetBinding,
+            }]
+        })
+        .visit(|closure_parameter: ast::LambdaExpr| {
+            if let Some(param_list) = closure_parameter.param_list() {
+                param_list
+                    .params()
+                    .filter(|closure_param| closure_param.ascribed_type().is_none())
+                    .map(|closure_param| {
+                        let closure_param_syntax = closure_param.syntax();
+                        InlayHint {
+                            range: closure_param_syntax.text_range(),
+                            text: closure_param_syntax.text().to_smol_string(),
+                            inlay_kind: InlayKind::ClosureParameter,
+                        }
+                    })
+                    .collect()
+            } else {
+                Vec::new()
+            }
+        })
+        .accept(&node)
+        .unwrap_or_else(Vec::new)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use insta::assert_debug_snapshot_matches;
+
+    #[test]
+    fn test_inlay_hints() {
+        let file = SourceFile::parse(
+            r#"
+struct OuterStruct {}
+
+fn main() {
+    struct InnerStruct {}
+
+    let test = 54;
+    let test = InnerStruct {};
+    let test = OuterStruct {};
+    let test = vec![222];
+    let mut test = Vec::new();
+    test.push(333);
+    let test = test.into_iter().map(|i| i * i).collect::<Vec<_>>();
+    let mut test = 33;
+    let _ = 22;
+    let test: Vec<_> = (0..3).collect();
+
+    let _ = (0..23).map(|i: u32| {
+        let i_squared = i * i;
+        i_squared
+    });
+    
+    let test: i32 = 33;
+
+    let (x, c) = (42, 'a');
+    let test = (42, 'a');
+}
+
+"#,
+        )
+        .ok()
+        .unwrap();
+        let hints = inlay_hints(&file);
+        assert_debug_snapshot_matches!("inlay_hints", hints);
+    }
+}