Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/ide/src/inlay_hints/param_name.rs')
| -rw-r--r-- | crates/ide/src/inlay_hints/param_name.rs | 237 |
1 files changed, 237 insertions, 0 deletions
diff --git a/crates/ide/src/inlay_hints/param_name.rs b/crates/ide/src/inlay_hints/param_name.rs new file mode 100644 index 0000000000..2675e7e80f --- /dev/null +++ b/crates/ide/src/inlay_hints/param_name.rs @@ -0,0 +1,237 @@ +use either::Either; +use hir::{Callable, Semantics}; +use ide_db::{base_db::FileRange, RootDatabase}; + +use stdx::to_lower_snake_case; +use syntax::ast::{self, AstNode, HasArgList, HasName, UnaryOp}; + +use crate::{InlayHint, InlayHintsConfig, InlayKind, InlayTooltip}; + +pub(super) fn hints( + acc: &mut Vec<InlayHint>, + sema: &Semantics<'_, RootDatabase>, + config: &InlayHintsConfig, + expr: ast::Expr, +) -> Option<()> { + if !config.parameter_hints { + return None; + } + + let (callable, arg_list) = get_callable(sema, &expr)?; + let hints = callable + .params(sema.db) + .into_iter() + .zip(arg_list.args()) + .filter_map(|((param, _ty), arg)| { + // Only annotate hints for expressions that exist in the original file + let range = sema.original_range_opt(arg.syntax())?; + let (param_name, name_syntax) = match param.as_ref()? { + Either::Left(pat) => ("self".to_string(), pat.name()), + Either::Right(pat) => match pat { + ast::Pat::IdentPat(it) => (it.name()?.to_string(), it.name()), + _ => return None, + }, + }; + Some((name_syntax, param_name, arg, range)) + }) + .filter(|(_, param_name, arg, _)| { + !should_hide_param_name_hint(sema, &callable, param_name, arg) + }) + .map(|(param, param_name, _, FileRange { range, .. })| { + let mut tooltip = None; + if let Some(name) = param { + if let hir::CallableKind::Function(f) = callable.kind() { + // assert the file is cached so we can map out of macros + if let Some(_) = sema.source(f) { + tooltip = sema.original_range_opt(name.syntax()); + } + } + } + + InlayHint { + range, + kind: InlayKind::ParameterHint, + label: param_name.into(), + tooltip: tooltip.map(|it| InlayTooltip::HoverOffset(it.file_id, it.range.start())), + } + }); + + acc.extend(hints); + Some(()) +} + +fn get_callable( + sema: &Semantics<'_, RootDatabase>, + expr: &ast::Expr, +) -> Option<(hir::Callable, ast::ArgList)> { + match expr { + ast::Expr::CallExpr(expr) => { + let descended = sema.descend_node_into_attributes(expr.clone()).pop(); + let expr = descended.as_ref().unwrap_or(expr); + sema.type_of_expr(&expr.expr()?)?.original.as_callable(sema.db).zip(expr.arg_list()) + } + ast::Expr::MethodCallExpr(expr) => { + let descended = sema.descend_node_into_attributes(expr.clone()).pop(); + let expr = descended.as_ref().unwrap_or(expr); + sema.resolve_method_call_as_callable(expr).zip(expr.arg_list()) + } + _ => None, + } +} + +fn should_hide_param_name_hint( + sema: &Semantics<'_, RootDatabase>, + callable: &hir::Callable, + param_name: &str, + argument: &ast::Expr, +) -> bool { + // These are to be tested in the `parameter_hint_heuristics` test + // hide when: + // - the parameter name is a suffix of the function's name + // - the argument is a qualified constructing or call expression where the qualifier is an ADT + // - exact argument<->parameter match(ignoring leading underscore) or parameter is a prefix/suffix + // of argument with _ splitting it off + // - param starts with `ra_fixture` + // - param is a well known name in a unary function + + let param_name = param_name.trim_start_matches('_'); + if param_name.is_empty() { + return true; + } + + if matches!(argument, ast::Expr::PrefixExpr(prefix) if prefix.op_kind() == Some(UnaryOp::Not)) { + return false; + } + + let fn_name = match callable.kind() { + hir::CallableKind::Function(it) => Some(it.name(sema.db).to_smol_str()), + _ => None, + }; + let fn_name = fn_name.as_deref(); + is_param_name_suffix_of_fn_name(param_name, callable, fn_name) + || is_argument_similar_to_param_name(argument, param_name) + || param_name.starts_with("ra_fixture") + || (callable.n_params() == 1 && is_obvious_param(param_name)) + || is_adt_constructor_similar_to_param_name(sema, argument, param_name) +} + +/// Hide the parameter name of a unary function if it is a `_` - prefixed suffix of the function's name, or equal. +/// +/// `fn strip_suffix(suffix)` will be hidden. +/// `fn stripsuffix(suffix)` will not be hidden. +fn is_param_name_suffix_of_fn_name( + param_name: &str, + callable: &Callable, + fn_name: Option<&str>, +) -> bool { + match (callable.n_params(), fn_name) { + (1, Some(function)) => { + function == param_name + || function + .len() + .checked_sub(param_name.len()) + .and_then(|at| function.is_char_boundary(at).then(|| function.split_at(at))) + .map_or(false, |(prefix, suffix)| { + suffix.eq_ignore_ascii_case(param_name) && prefix.ends_with('_') + }) + } + _ => false, + } +} + +fn is_argument_similar_to_param_name(argument: &ast::Expr, param_name: &str) -> bool { + // check whether param_name and argument are the same or + // whether param_name is a prefix/suffix of argument(split at `_`) + let argument = match get_string_representation(argument) { + Some(argument) => argument, + None => return false, + }; + + // std is honestly too panic happy... + let str_split_at = |str: &str, at| str.is_char_boundary(at).then(|| argument.split_at(at)); + + let param_name = param_name.trim_start_matches('_'); + let argument = argument.trim_start_matches('_'); + + match str_split_at(argument, param_name.len()) { + Some((prefix, rest)) if prefix.eq_ignore_ascii_case(param_name) => { + return rest.is_empty() || rest.starts_with('_'); + } + _ => (), + } + match argument.len().checked_sub(param_name.len()).and_then(|at| str_split_at(argument, at)) { + Some((rest, suffix)) if param_name.eq_ignore_ascii_case(suffix) => { + return rest.is_empty() || rest.ends_with('_'); + } + _ => (), + } + false +} + +fn get_string_representation(expr: &ast::Expr) -> Option<String> { + match expr { + ast::Expr::MethodCallExpr(method_call_expr) => { + let name_ref = method_call_expr.name_ref()?; + match name_ref.text().as_str() { + "clone" | "as_ref" => method_call_expr.receiver().map(|rec| rec.to_string()), + name_ref => Some(name_ref.to_owned()), + } + } + ast::Expr::MacroExpr(macro_expr) => { + Some(macro_expr.macro_call()?.path()?.segment()?.to_string()) + } + ast::Expr::FieldExpr(field_expr) => Some(field_expr.name_ref()?.to_string()), + ast::Expr::PathExpr(path_expr) => Some(path_expr.path()?.segment()?.to_string()), + ast::Expr::PrefixExpr(prefix_expr) => get_string_representation(&prefix_expr.expr()?), + ast::Expr::RefExpr(ref_expr) => get_string_representation(&ref_expr.expr()?), + ast::Expr::CastExpr(cast_expr) => get_string_representation(&cast_expr.expr()?), + _ => None, + } +} + +fn is_obvious_param(param_name: &str) -> bool { + // avoid displaying hints for common functions like map, filter, etc. + // or other obvious words used in std + let is_obvious_param_name = + matches!(param_name, "predicate" | "value" | "pat" | "rhs" | "other"); + param_name.len() == 1 || is_obvious_param_name +} + +fn is_adt_constructor_similar_to_param_name( + sema: &Semantics<'_, RootDatabase>, + argument: &ast::Expr, + param_name: &str, +) -> bool { + let path = match argument { + ast::Expr::CallExpr(c) => c.expr().and_then(|e| match e { + ast::Expr::PathExpr(p) => p.path(), + _ => None, + }), + ast::Expr::PathExpr(p) => p.path(), + ast::Expr::RecordExpr(r) => r.path(), + _ => return false, + }; + let path = match path { + Some(it) => it, + None => return false, + }; + (|| match sema.resolve_path(&path)? { + hir::PathResolution::Def(hir::ModuleDef::Adt(_)) => { + Some(to_lower_snake_case(&path.segment()?.name_ref()?.text()) == param_name) + } + hir::PathResolution::Def(hir::ModuleDef::Function(_) | hir::ModuleDef::Variant(_)) => { + if to_lower_snake_case(&path.segment()?.name_ref()?.text()) == param_name { + return Some(true); + } + let qual = path.qualifier()?; + match sema.resolve_path(&qual)? { + hir::PathResolution::Def(hir::ModuleDef::Adt(_)) => { + Some(to_lower_snake_case(&qual.segment()?.name_ref()?.text()) == param_name) + } + _ => None, + } + } + _ => None, + })() + .unwrap_or(false) +} |