pull out suggest_name::* to utils; enchance heuristics

Author: cpud36

crates/ide_assists/src/handlers/extract_variable.rs

@@ -1,15 +1,14 @@
-use itertools::Itertools;
-use stdx::{format_to, to_lower_snake_case};
+use stdx::format_to;
 use syntax::{
-    ast::{self, AstNode, NameOwner},
+    ast::{self, AstNode},
     SyntaxKind::{
         BLOCK_EXPR, BREAK_EXPR, CLOSURE_EXPR, COMMENT, LOOP_EXPR, MATCH_ARM, PATH_EXPR, RETURN_EXPR,
     },
     SyntaxNode,
 };
 use test_utils::mark;
 
-use crate::{AssistContext, AssistId, AssistKind, Assists};
+use crate::{utils::suggest_name, AssistContext, AssistId, AssistKind, Assists};
 
 // Assist: extract_variable
 //
@@ -55,7 +54,7 @@ pub(crate) fn extract_variable(acc: &mut Assists, ctx: &AssistContext) -> Option
 
             let var_name = match &field_shorthand {
                 Some(it) => it.to_string(),
-                None => suggest_variable_name(ctx, &to_extract),
+                None => suggest_name::variable(&to_extract, &ctx.sema),
             };
             let expr_range = match &field_shorthand {
                 Some(it) => it.syntax().text_range().cover(to_extract.syntax().text_range()),
@@ -174,89 +173,6 @@ impl Anchor {
     }
 }
 
-fn suggest_variable_name(ctx: &AssistContext, expr: &ast::Expr) -> String {
-    // FIXME: account for existing names in the scope
-    suggest_name_from_param(ctx, expr)
-        .or_else(|| suggest_name_from_func(expr))
-        .or_else(|| suggest_name_from_method(expr))
-        .or_else(|| suggest_name_by_type(ctx, expr))
-        .unwrap_or_else(|| "var_name".to_string())
-}
-
-fn normalize_name(name: &str) -> Option<String> {
-    let name = to_lower_snake_case(name);
-
-    let useless_names = ["new", "default", "some", "none", "ok", "err"];
-    if useless_names.contains(&name.as_str()) {
-        return None;
-    }
-
-    Some(name)
-}
-
-fn suggest_name_from_func(expr: &ast::Expr) -> Option<String> {
-    let call = match expr {
-        ast::Expr::CallExpr(call) => call,
-        _ => return None,
-    };
-    let func = match call.expr()? {
-        ast::Expr::PathExpr(path) => path,
-        _ => return None,
-    };
-    let ident = func.path()?.segment()?.name_ref()?.ident_token()?;
-    normalize_name(ident.text())
-}
-
-fn suggest_name_from_method(expr: &ast::Expr) -> Option<String> {
-    let method = match expr {
-        ast::Expr::MethodCallExpr(call) => call,
-        _ => return None,
-    };
-    let ident = method.name_ref()?.ident_token()?;
-    normalize_name(ident.text())
-}
-
-fn suggest_name_from_param(ctx: &AssistContext, expr: &ast::Expr) -> Option<String> {
-    let arg_list = expr.syntax().parent().and_then(ast::ArgList::cast)?;
-    let args_parent = arg_list.syntax().parent()?;
-    let func = if let Some(call) = ast::CallExpr::cast(args_parent.clone()) {
-        let func = call.expr()?;
-        let func_ty = ctx.sema.type_of_expr(&func)?;
-        func_ty.as_callable(ctx.db())?
-    } else if let Some(method) = ast::MethodCallExpr::cast(args_parent) {
-        ctx.sema.resolve_method_call_as_callable(&method)?
-    } else {
-        return None;
-    };
-
-    let (idx, _) = arg_list.args().find_position(|it| it == expr).unwrap();
-    let (pat, _) = func.params(ctx.db()).into_iter().nth(idx)?;
-    let param = match pat? {
-        either::Either::Right(ast::Pat::IdentPat(param)) => param,
-        _ => return None,
-    };
-    let name = param.name()?;
-    normalize_name(&name.to_string())
-}
-
-fn suggest_name_by_type(ctx: &AssistContext, expr: &ast::Expr) -> Option<String> {
-    let ty = ctx.sema.type_of_expr(expr)?;
-    let ty = ty.remove_ref().unwrap_or(ty);
-
-    name_from_type(ty, ctx)
-}
-
-fn name_from_type(ty: hir::Type, ctx: &AssistContext) -> Option<String> {
-    let name = if let Some(adt) = ty.as_adt() {
-        adt.name(ctx.db()).to_string()
-    } else if let Some(trait_) = ty.as_dyn_trait() {
-        trait_.name(ctx.db()).to_string()
-    } else {
-        return None;
-    };
-    normalize_name(&name)
-}
-
 #[cfg(test)]
 mod tests {
     use test_utils::mark;

crates/ide_assists/src/tests.rs

@@ -12,7 +12,7 @@ use ide_db::{
     RootDatabase,
 };
 use stdx::{format_to, trim_indent};
-use syntax::TextRange;
+use syntax::{ast, AstNode, TextRange};
 use test_utils::{assert_eq_text, extract_offset};
 
 use crate::{handlers::Handler, Assist, AssistConfig, AssistContext, AssistKind, Assists};
@@ -180,6 +180,50 @@ fn labels(assists: &[Assist]) -> String {
     labels.into_iter().collect::<String>()
 }
 
+pub(crate) type NameSuggestion = fn(&ast::Expr, &Semantics<'_, RootDatabase>) -> Option<String>;
+
+#[track_caller]
+pub(crate) fn check_name_suggestion(
+    suggestion: NameSuggestion,
+    ra_fixture: &str,
+    suggested_name: &str,
+) {
+    check_name(suggestion, ra_fixture, Some(suggested_name));
+}
+
+#[track_caller]
+pub(crate) fn check_name_suggestion_not_applicable(suggestion: NameSuggestion, ra_fixture: &str) {
+    check_name(suggestion, ra_fixture, None);
+}
+
+#[track_caller]
+fn check_name(suggestion: NameSuggestion, ra_fixture: &str, expected: Option<&str>) {
+    let (db, file_with_carret_id, range_or_offset) = RootDatabase::with_range_or_offset(ra_fixture);
+    let frange = FileRange { file_id: file_with_carret_id, range: range_or_offset.into() };
+
+    let sema = Semantics::new(&db);
+    let source_file = sema.parse(frange.file_id);
+    let element = source_file.syntax().covering_element(frange.range);
+    let expr =
+        element.ancestors().find_map(ast::Expr::cast).expect("selection is not an expression");
+    assert_eq!(
+        expr.syntax().text_range(),
+        frange.range,
+        "selection is not an expression(yet contained in one)"
+    );
+
+    let name = suggestion(&expr, &sema);
+
+    match (name, expected) {
+        (Some(name), Some(expected_name)) => {
+            assert_eq_text!(&name, expected_name);
+        }
+        (Some(_), None) => panic!("name suggestion should not be applicable"),
+        (None, Some(_)) => panic!("name suggestion is not applicable"),
+        (None, None) => (),
+    }
+}
+
 #[test]
 fn assist_order_field_struct() {
     let before = "struct Foo { $0bar: u32 }";

crates/ide_assists/src/utils.rs

@@ -1,5 +1,7 @@
 //! Assorted functions shared by several assists.
 
+pub(crate) mod suggest_name;
+
 use std::ops;
 
 use ast::TypeBoundsOwner;