Initial implementation of view-hir command

2 files changed, 44 insertions, 0 deletions

diff --git a/crates/ide/src/lib.rs b/crates/ide/src/lib.rs
index 41eb139d1..25c2047ca 100644
--- a/crates/ide/src/lib.rs
+++ b/crates/ide/src/lib.rs
@@ -31,6 +31,7 @@ mod folding_ranges;
 mod goto_definition;
 mod goto_implementation;
 mod goto_type_definition;
+mod view_hir;
 mod hover;
 mod inlay_hints;
 mod join_lines;
@@ -271,6 +272,10 @@ impl Analysis {
         self.with_db(|db| syntax_tree::syntax_tree(&db, file_id, text_range))
     }
 
+    pub fn view_hir(&self, position: FilePosition) -> Cancelable<String> {
+        self.with_db(|db| view_hir::view_hir(&db, position))
+    }
+
     pub fn expand_macro(&self, position: FilePosition) -> Cancelable<Option<ExpandedMacro>> {
         self.with_db(|db| expand_macro::expand_macro(db, position))
     }
diff --git a/crates/ide/src/view_hir.rs b/crates/ide/src/view_hir.rs
new file mode 100644
index 000000000..e48f2cfe0
--- /dev/null
+++ b/crates/ide/src/view_hir.rs
@@ -0,0 +1,39 @@
+use hir::{Function, Semantics};
+use hir::db::DefDatabase;
+use ide_db::base_db::FilePosition;
+use ide_db::RootDatabase;
+use syntax::{AstNode, algo::find_node_at_offset, ast};
+use std::fmt::Write;
+
+// Feature: View hir
+//
+// |===
+// | Editor  | Action Name
+//
+// | VS Code | **Rust Analyzer: View Hir**
+// |===
+pub(crate) fn view_hir(db: &RootDatabase, position: FilePosition) -> String {
+    body_hir(db, position).unwrap_or("Not inside a function body".to_string())
+}
+
+fn body_hir(db: &RootDatabase, position: FilePosition) -> Option<String> {
+    let sema = Semantics::new(db);
+    let source_file = sema.parse(position.file_id);
+
+    let function = find_node_at_offset::<ast::Fn>(
+        source_file.syntax(),
+        position.offset,
+    )?;
+
+    let function: Function = sema.to_def(&function)?;
+    let body = db.body(function.id.into());
+
+    let mut result = String::new();
+    writeln!(&mut result, "== Body expressions ==").ok()?;
+
+    for (id, expr) in body.exprs.iter() {
+        writeln!(&mut result, "{:?}: {:?}", id, expr).ok()?;
+    }
+
+    Some(result)
+}
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