Merge #5928

5928: Add method references CodeLens r=vsrs a=vsrs

The PR adds CodeLens for methods and  free-standing functions:

![method_refs](https://user-images.githubusercontent.com/62505555/91858244-95fbfb00-ec71-11ea-90c7-5b3ee067e305.png)

Relates to #5836

Co-authored-by: vsrs <[email protected]>

1 files changed, 95 insertions, 0 deletions

diff --git a/crates/ide/src/fn_references.rs b/crates/ide/src/fn_references.rs
new file mode 100644
index 000000000..1989a562b
--- /dev/null
+++ b/crates/ide/src/fn_references.rs
@@ -0,0 +1,95 @@
+//! This module implements a methods and free functions search in the specified file.
+//! We have to skip tests, so cannot reuse file_structure module.
+
+use hir::Semantics;
+use ide_db::RootDatabase;
+use syntax::{ast, ast::NameOwner, AstNode, SyntaxNode};
+
+use crate::{runnables::has_test_related_attribute, FileId, FileRange};
+
+pub(crate) fn find_all_methods(db: &RootDatabase, file_id: FileId) -> Vec<FileRange> {
+    let sema = Semantics::new(db);
+    let source_file = sema.parse(file_id);
+    source_file.syntax().descendants().filter_map(|it| method_range(it, file_id)).collect()
+}
+
+fn method_range(item: SyntaxNode, file_id: FileId) -> Option<FileRange> {
+    ast::Fn::cast(item).and_then(|fn_def| {
+        if has_test_related_attribute(&fn_def) {
+            None
+        } else {
+            fn_def.name().map(|name| FileRange { file_id, range: name.syntax().text_range() })
+        }
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::mock_analysis::analysis_and_position;
+    use crate::{FileRange, TextSize};
+    use std::ops::RangeInclusive;
+
+    #[test]
+    fn test_find_all_methods() {
+        let (analysis, pos) = analysis_and_position(
+            r#"
+            //- /lib.rs
+            fn private_fn() {<|>}
+
+            pub fn pub_fn() {}
+
+            pub fn generic_fn<T>(arg: T) {}
+        "#,
+        );
+
+        let refs = analysis.find_all_methods(pos.file_id).unwrap();
+        check_result(&refs, &[3..=13, 27..=33, 47..=57]);
+    }
+
+    #[test]
+    fn test_find_trait_methods() {
+        let (analysis, pos) = analysis_and_position(
+            r#"
+            //- /lib.rs
+            trait Foo {
+                fn bar() {<|>}
+                fn baz() {}
+            }
+        "#,
+        );
+
+        let refs = analysis.find_all_methods(pos.file_id).unwrap();
+        check_result(&refs, &[19..=22, 35..=38]);
+    }
+
+    #[test]
+    fn test_skip_tests() {
+        let (analysis, pos) = analysis_and_position(
+            r#"
+            //- /lib.rs
+            #[test]
+            fn foo() {<|>}
+
+            pub fn pub_fn() {}
+
+            mod tests {
+                #[test]
+                fn bar() {}
+            }
+        "#,
+        );
+
+        let refs = analysis.find_all_methods(pos.file_id).unwrap();
+        check_result(&refs, &[28..=34]);
+    }
+
+    fn check_result(refs: &[FileRange], expected: &[RangeInclusive<u32>]) {
+        assert_eq!(refs.len(), expected.len());
+
+        for (i, item) in refs.iter().enumerate() {
+            let range = &expected[i];
+            assert_eq!(TextSize::from(*range.start()), item.range.start());
+            assert_eq!(TextSize::from(*range.end()), item.range.end());
+        }
+    }
+}