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Replace big if/else expression with match #3387

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Merged
merged 2 commits into from Nov 2, 2018
Merged

Replace big if/else expression with match #3387

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4e054ad
Replace big if/else expression with match
Oct 31, 2018
0a41dfd
Use slice patterns instead of padding
Nov 1, 2018
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92 changes: 36 additions & 56 deletions clippy_lints/src/methods/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -16,12 +16,13 @@ use crate::rustc::{declare_tool_lint, lint_array};
use crate::rustc_errors::Applicability;
use crate::syntax::ast;
use crate::syntax::source_map::{BytePos, Span};
use crate::syntax::symbol::LocalInternedString;
use crate::utils::paths;
use crate::utils::sugg;
use crate::utils::{
get_arg_name, get_trait_def_id, implements_trait, in_macro, is_copy, is_expn_of, is_self, is_self_ty,
iter_input_pats, last_path_segment, match_def_path, match_path, match_qpath, match_trait_method, match_type,
match_var, method_chain_args, remove_blocks, return_ty, same_tys, single_segment_path, snippet, snippet_with_macro_callsite, span_lint,
match_var, method_calls, method_chain_args, remove_blocks, return_ty, same_tys, single_segment_path, snippet, snippet_with_macro_callsite, span_lint,
span_lint_and_sugg, span_lint_and_then, span_note_and_lint, walk_ptrs_ty, walk_ptrs_ty_depth, SpanlessEq,
};
use if_chain::if_chain;
Expand Down Expand Up @@ -783,63 +784,42 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
return;
}

let (method_names, arg_lists) = method_calls(expr, 2);
let method_names: Vec<LocalInternedString> = method_names.iter().map(|s| s.as_str()).collect();
let method_names: Vec<&str> = method_names.iter().map(|s| s.as_ref()).collect();

match method_names.as_slice() {
["unwrap", "get"] => lint_get_unwrap(cx, expr, arg_lists[1], false),
["unwrap", "get_mut"] => lint_get_unwrap(cx, expr, arg_lists[1], true),
["unwrap", ..] => lint_unwrap(cx, expr, arg_lists[0]),
["expect", "ok"] => lint_ok_expect(cx, expr, arg_lists[1]),
["unwrap_or", "map"] => lint_map_unwrap_or(cx, expr, arg_lists[1], arg_lists[0]),
["unwrap_or_else", "map"] => lint_map_unwrap_or_else(cx, expr, arg_lists[1], arg_lists[0]),
["map_or", ..] => lint_map_or_none(cx, expr, arg_lists[0]),
["next", "filter"] => lint_filter_next(cx, expr, arg_lists[1]),
["map", "filter"] => lint_filter_map(cx, expr, arg_lists[1], arg_lists[0]),
["map", "filter_map"] => lint_filter_map_map(cx, expr, arg_lists[1], arg_lists[0]),
["flat_map", "filter"] => lint_filter_flat_map(cx, expr, arg_lists[1], arg_lists[0]),
["flat_map", "filter_map"] => lint_filter_map_flat_map(cx, expr, arg_lists[1], arg_lists[0]),
["flatten", "map"] => lint_map_flatten(cx, expr, arg_lists[1]),
["is_some", "find"] => lint_search_is_some(cx, expr, "find", arg_lists[1], arg_lists[0]),
["is_some", "position"] => lint_search_is_some(cx, expr, "position", arg_lists[1], arg_lists[0]),
["is_some", "rposition"] => lint_search_is_some(cx, expr, "rposition", arg_lists[1], arg_lists[0]),
["extend", ..] => lint_extend(cx, expr, arg_lists[0]),
["as_ptr", "unwrap"] => lint_cstring_as_ptr(cx, expr, &arg_lists[1][0], &arg_lists[0][0]),
["nth", "iter"] => lint_iter_nth(cx, expr, arg_lists[1], false),
["nth", "iter_mut"] => lint_iter_nth(cx, expr, arg_lists[1], true),
["next", "skip"] => lint_iter_skip_next(cx, expr),
["collect", "cloned"] => lint_iter_cloned_collect(cx, expr, arg_lists[1]),
["as_ref", ..] => lint_asref(cx, expr, "as_ref", arg_lists[0]),
["as_mut", ..] => lint_asref(cx, expr, "as_mut", arg_lists[0]),
["fold", ..] => lint_unnecessary_fold(cx, expr, arg_lists[0]),
["filter_map", ..] => unnecessary_filter_map::lint(cx, expr, arg_lists[0]),
_ => {}
}

match expr.node {
hir::ExprKind::MethodCall(ref method_call, ref method_span, ref args) => {
// Chain calls
// GET_UNWRAP needs to be checked before general `UNWRAP` lints
if let Some(arglists) = method_chain_args(expr, &["get", "unwrap"]) {
lint_get_unwrap(cx, expr, arglists[0], false);
} else if let Some(arglists) = method_chain_args(expr, &["get_mut", "unwrap"]) {
lint_get_unwrap(cx, expr, arglists[0], true);
} else if let Some(arglists) = method_chain_args(expr, &["unwrap"]) {
lint_unwrap(cx, expr, arglists[0]);
} else if let Some(arglists) = method_chain_args(expr, &["ok", "expect"]) {
lint_ok_expect(cx, expr, arglists[0]);
} else if let Some(arglists) = method_chain_args(expr, &["map", "unwrap_or"]) {
lint_map_unwrap_or(cx, expr, arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["map", "unwrap_or_else"]) {
lint_map_unwrap_or_else(cx, expr, arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["map_or"]) {
lint_map_or_none(cx, expr, arglists[0]);
} else if let Some(arglists) = method_chain_args(expr, &["filter", "next"]) {
lint_filter_next(cx, expr, arglists[0]);
} else if let Some(arglists) = method_chain_args(expr, &["filter", "map"]) {
lint_filter_map(cx, expr, arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["filter_map", "map"]) {
lint_filter_map_map(cx, expr, arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["filter", "flat_map"]) {
lint_filter_flat_map(cx, expr, arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["filter_map", "flat_map"]) {
lint_filter_map_flat_map(cx, expr, arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["map", "flatten"]) {
lint_map_flatten(cx, expr, arglists[0]);
} else if let Some(arglists) = method_chain_args(expr, &["find", "is_some"]) {
lint_search_is_some(cx, expr, "find", arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["position", "is_some"]) {
lint_search_is_some(cx, expr, "position", arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["rposition", "is_some"]) {
lint_search_is_some(cx, expr, "rposition", arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["extend"]) {
lint_extend(cx, expr, arglists[0]);
} else if let Some(arglists) = method_chain_args(expr, &["unwrap", "as_ptr"]) {
lint_cstring_as_ptr(cx, expr, &arglists[0][0], &arglists[1][0]);
} else if let Some(arglists) = method_chain_args(expr, &["iter", "nth"]) {
lint_iter_nth(cx, expr, arglists[0], false);
} else if let Some(arglists) = method_chain_args(expr, &["iter_mut", "nth"]) {
lint_iter_nth(cx, expr, arglists[0], true);
} else if method_chain_args(expr, &["skip", "next"]).is_some() {
lint_iter_skip_next(cx, expr);
} else if let Some(arglists) = method_chain_args(expr, &["cloned", "collect"]) {
lint_iter_cloned_collect(cx, expr, arglists[0]);
} else if let Some(arglists) = method_chain_args(expr, &["as_ref"]) {
lint_asref(cx, expr, "as_ref", arglists[0]);
} else if let Some(arglists) = method_chain_args(expr, &["as_mut"]) {
lint_asref(cx, expr, "as_mut", arglists[0]);
} else if let Some(arglists) = method_chain_args(expr, &["fold"]) {
lint_unnecessary_fold(cx, expr, arglists[0]);
} else if let Some(arglists) = method_chain_args(expr, &["filter_map"]) {
unnecessary_filter_map::lint(cx, expr, arglists[0]);
}

lint_or_fun_call(cx, expr, *method_span, &method_call.ident.as_str(), args);
lint_expect_fun_call(cx, expr, *method_span, &method_call.ident.as_str(), args);
Expand Down
25 changes: 24 additions & 1 deletion clippy_lints/src/utils/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@ use crate::syntax::ast::{self, LitKind};
use crate::syntax::attr;
use crate::syntax::source_map::{Span, DUMMY_SP};
use crate::syntax::errors::DiagnosticBuilder;
use crate::syntax::symbol::keywords;
use crate::syntax::symbol::{keywords, Symbol};

pub mod camel_case;

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

/// Return the method names and argument list of nested method call expressions that make up
/// `expr`.
pub fn method_calls<'a>(expr: &'a Expr, max_depth: usize) -> (Vec<Symbol>, Vec<&'a [Expr]>) {
let mut method_names = Vec::with_capacity(max_depth);
let mut arg_lists = Vec::with_capacity(max_depth);

let mut current = expr;
for _ in 0..max_depth {
if let ExprKind::MethodCall(path, _, args) = &current.node {
if args.iter().any(|e| in_macro(e.span)) {
break;
}
method_names.push(path.ident.name);
arg_lists.push(&**args);
current = &args[0];
} else {
break;
}
}

(method_names, arg_lists)
}

/// Match an `Expr` against a chain of methods, and return the matched `Expr`s.
///
/// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
Expand Down