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author
Michael Wright
committed
Replace big if/else expression with match
1 parent e695015 commit 4e054ad

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2 files changed

+60
-57
lines changed

2 files changed

+60
-57
lines changed

‎clippy_lints/src/methods/mod.rs

+36-56
Original file line numberDiff line numberDiff line change
@@ -16,12 +16,13 @@ use crate::rustc::{declare_tool_lint, lint_array};
1616
use crate::rustc_errors::Applicability;
1717
use crate::syntax::ast;
1818
use crate::syntax::source_map::{BytePos, Span};
19+
use crate::syntax::symbol::LocalInternedString;
1920
use crate::utils::paths;
2021
use crate::utils::sugg;
2122
use crate::utils::{
2223
get_arg_name, get_trait_def_id, implements_trait, in_macro, is_copy, is_expn_of, is_self, is_self_ty,
2324
iter_input_pats, last_path_segment, match_def_path, match_path, match_qpath, match_trait_method, match_type,
24-
match_var, method_chain_args, remove_blocks, return_ty, same_tys, single_segment_path, snippet, snippet_with_macro_callsite, span_lint,
25+
match_var, method_calls, method_chain_args, remove_blocks, return_ty, same_tys, single_segment_path, snippet, snippet_with_macro_callsite, span_lint,
2526
span_lint_and_sugg, span_lint_and_then, span_note_and_lint, walk_ptrs_ty, walk_ptrs_ty_depth, SpanlessEq,
2627
};
2728
use if_chain::if_chain;
@@ -783,63 +784,42 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
783784
return;
784785
}
785786

787+
let (method_names, arg_lists) = method_calls(expr, 2);
788+
let method_names: Vec<LocalInternedString> = method_names.iter().map(|s| s.as_str()).collect();
789+
let mut method_names = method_names.iter().map(|s| s.as_ref()).chain(iter::repeat(""));
790+
791+
match [method_names.next().unwrap(), method_names.next().unwrap()] {
792+
["unwrap", "get"] => lint_get_unwrap(cx, expr, arg_lists[1], false),
793+
["unwrap", "get_mut"] => lint_get_unwrap(cx, expr, arg_lists[1], true),
794+
["unwrap", _] => lint_unwrap(cx, expr, arg_lists[0]),
795+
["expect", "ok"] => lint_ok_expect(cx, expr, arg_lists[1]),
796+
["unwrap_or", "map"] => lint_map_unwrap_or(cx, expr, arg_lists[1], arg_lists[0]),
797+
["unwrap_or_else", "map"] => lint_map_unwrap_or_else(cx, expr, arg_lists[1], arg_lists[0]),
798+
["map_or", _] => lint_map_or_none(cx, expr, arg_lists[0]),
799+
["next", "filter"] => lint_filter_next(cx, expr, arg_lists[1]),
800+
["map", "filter"] => lint_filter_map(cx, expr, arg_lists[1], arg_lists[0]),
801+
["map", "filter_map"] => lint_filter_map_map(cx, expr, arg_lists[1], arg_lists[0]),
802+
["flat_map", "filter"] => lint_filter_flat_map(cx, expr, arg_lists[1], arg_lists[0]),
803+
["flat_map", "filter_map"] => lint_filter_map_flat_map(cx, expr, arg_lists[1], arg_lists[0]),
804+
["flatten", "map"] => lint_map_flatten(cx, expr, arg_lists[1]),
805+
["is_some", "find"] => lint_search_is_some(cx, expr, "find", arg_lists[1], arg_lists[0]),
806+
["is_some", "position"] => lint_search_is_some(cx, expr, "position", arg_lists[1], arg_lists[0]),
807+
["is_some", "rposition"] => lint_search_is_some(cx, expr, "rposition", arg_lists[1], arg_lists[0]),
808+
["extend", _] => lint_extend(cx, expr, arg_lists[0]),
809+
["as_ptr", "unwrap"] => lint_cstring_as_ptr(cx, expr, &arg_lists[1][0], &arg_lists[0][0]),
810+
["nth", "iter"] => lint_iter_nth(cx, expr, arg_lists[1], false),
811+
["nth", "iter_mut"] => lint_iter_nth(cx, expr, arg_lists[1], true),
812+
["next", "skip"] => lint_iter_skip_next(cx, expr),
813+
["collect", "cloned"] => lint_iter_cloned_collect(cx, expr, arg_lists[1]),
814+
["as_ref", _] => lint_asref(cx, expr, "as_ref", arg_lists[0]),
815+
["as_mut", _] => lint_asref(cx, expr, "as_mut", arg_lists[0]),
816+
["fold", _] => lint_unnecessary_fold(cx, expr, arg_lists[0]),
817+
["filter_map", _] => unnecessary_filter_map::lint(cx, expr, arg_lists[0]),
818+
_ => {}
819+
}
820+
786821
match expr.node {
787822
hir::ExprKind::MethodCall(ref method_call, ref method_span, ref args) => {
788-
// Chain calls
789-
// GET_UNWRAP needs to be checked before general `UNWRAP` lints
790-
if let Some(arglists) = method_chain_args(expr, &["get", "unwrap"]) {
791-
lint_get_unwrap(cx, expr, arglists[0], false);
792-
} else if let Some(arglists) = method_chain_args(expr, &["get_mut", "unwrap"]) {
793-
lint_get_unwrap(cx, expr, arglists[0], true);
794-
} else if let Some(arglists) = method_chain_args(expr, &["unwrap"]) {
795-
lint_unwrap(cx, expr, arglists[0]);
796-
} else if let Some(arglists) = method_chain_args(expr, &["ok", "expect"]) {
797-
lint_ok_expect(cx, expr, arglists[0]);
798-
} else if let Some(arglists) = method_chain_args(expr, &["map", "unwrap_or"]) {
799-
lint_map_unwrap_or(cx, expr, arglists[0], arglists[1]);
800-
} else if let Some(arglists) = method_chain_args(expr, &["map", "unwrap_or_else"]) {
801-
lint_map_unwrap_or_else(cx, expr, arglists[0], arglists[1]);
802-
} else if let Some(arglists) = method_chain_args(expr, &["map_or"]) {
803-
lint_map_or_none(cx, expr, arglists[0]);
804-
} else if let Some(arglists) = method_chain_args(expr, &["filter", "next"]) {
805-
lint_filter_next(cx, expr, arglists[0]);
806-
} else if let Some(arglists) = method_chain_args(expr, &["filter", "map"]) {
807-
lint_filter_map(cx, expr, arglists[0], arglists[1]);
808-
} else if let Some(arglists) = method_chain_args(expr, &["filter_map", "map"]) {
809-
lint_filter_map_map(cx, expr, arglists[0], arglists[1]);
810-
} else if let Some(arglists) = method_chain_args(expr, &["filter", "flat_map"]) {
811-
lint_filter_flat_map(cx, expr, arglists[0], arglists[1]);
812-
} else if let Some(arglists) = method_chain_args(expr, &["filter_map", "flat_map"]) {
813-
lint_filter_map_flat_map(cx, expr, arglists[0], arglists[1]);
814-
} else if let Some(arglists) = method_chain_args(expr, &["map", "flatten"]) {
815-
lint_map_flatten(cx, expr, arglists[0]);
816-
} else if let Some(arglists) = method_chain_args(expr, &["find", "is_some"]) {
817-
lint_search_is_some(cx, expr, "find", arglists[0], arglists[1]);
818-
} else if let Some(arglists) = method_chain_args(expr, &["position", "is_some"]) {
819-
lint_search_is_some(cx, expr, "position", arglists[0], arglists[1]);
820-
} else if let Some(arglists) = method_chain_args(expr, &["rposition", "is_some"]) {
821-
lint_search_is_some(cx, expr, "rposition", arglists[0], arglists[1]);
822-
} else if let Some(arglists) = method_chain_args(expr, &["extend"]) {
823-
lint_extend(cx, expr, arglists[0]);
824-
} else if let Some(arglists) = method_chain_args(expr, &["unwrap", "as_ptr"]) {
825-
lint_cstring_as_ptr(cx, expr, &arglists[0][0], &arglists[1][0]);
826-
} else if let Some(arglists) = method_chain_args(expr, &["iter", "nth"]) {
827-
lint_iter_nth(cx, expr, arglists[0], false);
828-
} else if let Some(arglists) = method_chain_args(expr, &["iter_mut", "nth"]) {
829-
lint_iter_nth(cx, expr, arglists[0], true);
830-
} else if method_chain_args(expr, &["skip", "next"]).is_some() {
831-
lint_iter_skip_next(cx, expr);
832-
} else if let Some(arglists) = method_chain_args(expr, &["cloned", "collect"]) {
833-
lint_iter_cloned_collect(cx, expr, arglists[0]);
834-
} else if let Some(arglists) = method_chain_args(expr, &["as_ref"]) {
835-
lint_asref(cx, expr, "as_ref", arglists[0]);
836-
} else if let Some(arglists) = method_chain_args(expr, &["as_mut"]) {
837-
lint_asref(cx, expr, "as_mut", arglists[0]);
838-
} else if let Some(arglists) = method_chain_args(expr, &["fold"]) {
839-
lint_unnecessary_fold(cx, expr, arglists[0]);
840-
} else if let Some(arglists) = method_chain_args(expr, &["filter_map"]) {
841-
unnecessary_filter_map::lint(cx, expr, arglists[0]);
842-
}
843823

844824
lint_or_fun_call(cx, expr, *method_span, &method_call.ident.as_str(), args);
845825
lint_expect_fun_call(cx, expr, *method_span, &method_call.ident.as_str(), args);

‎clippy_lints/src/utils/mod.rs

+24-1
Original file line numberDiff line numberDiff line change
@@ -31,7 +31,7 @@ use crate::syntax::ast::{self, LitKind};
3131
use crate::syntax::attr;
3232
use crate::syntax::source_map::{Span, DUMMY_SP};
3333
use crate::syntax::errors::DiagnosticBuilder;
34-
use crate::syntax::symbol::keywords;
34+
use crate::syntax::symbol::{keywords, Symbol};
3535

3636
pub mod camel_case;
3737

@@ -274,6 +274,29 @@ pub fn resolve_node(cx: &LateContext<'_, '_>, qpath: &QPath, id: HirId) -> def::
274274
cx.tables.qpath_def(qpath, id)
275275
}
276276

277+
/// Return the method names and argument list of nested method call expressions that make up
278+
/// `expr`.
279+
pub fn method_calls<'a>(expr: &'a Expr, max_depth: usize) -> (Vec<Symbol>, Vec<&'a [Expr]>) {
280+
let mut method_names = Vec::with_capacity(max_depth);
281+
let mut arg_lists = Vec::with_capacity(max_depth);
282+
283+
let mut current = expr;
284+
for _ in 0..max_depth {
285+
if let ExprKind::MethodCall(path, _, args) = &current.node {
286+
if args.iter().any(|e| in_macro(e.span)) {
287+
break;
288+
}
289+
method_names.push(path.ident.name);
290+
arg_lists.push(&**args);
291+
current = &args[0];
292+
} else {
293+
break;
294+
}
295+
}
296+
297+
(method_names, arg_lists)
298+
}
299+
277300
/// Match an `Expr` against a chain of methods, and return the matched `Expr`s.
278301
///
279302
/// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,

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