mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-11-28 07:30:57 +00:00
Refactor while let loop to its own module
This commit is contained in:
nahuakang
Yoshitomo Nakanishi
parent
287a4f8ab1
commit
7158c944a4
2 changed files with 92 additions and 84 deletions
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@ -12,14 +12,13 @@ mod needless_collect;
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mod never_loop;
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mod same_item_push;
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mod utils;
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mod while_let_loop;
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mod while_let_on_iterator;
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use crate::utils::sugg::Sugg;
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use crate::utils::{higher, snippet_with_applicability, span_lint_and_sugg, sugg};
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use rustc_errors::Applicability;
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use rustc_hir::{Block, Expr, ExprKind, LoopSource, MatchSource, Pat, StmtKind};
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use rustc_lint::{LateContext, LateLintPass, LintContext};
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use rustc_middle::lint::in_external_macro;
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use crate::utils::{higher, sugg};
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use rustc_hir::{Expr, ExprKind, LoopSource, Pat};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::source_map::Span;
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use utils::{get_span_of_entire_for_loop, make_iterator_snippet, IncrementVisitor, InitializeVisitor};
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@ -564,49 +563,7 @@ impl<'tcx> LateLintPass<'tcx> for Loops {
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if let ExprKind::Loop(ref block, _, LoopSource::Loop, _) = expr.kind {
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// also check for empty `loop {}` statements, skipping those in #[panic_handler]
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empty_loop::check_empty_loop(cx, expr, block);
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// extract the expression from the first statement (if any) in a block
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let inner_stmt_expr = extract_expr_from_first_stmt(block);
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// or extract the first expression (if any) from the block
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if let Some(inner) = inner_stmt_expr.or_else(|| extract_first_expr(block)) {
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if let ExprKind::Match(ref matchexpr, ref arms, ref source) = inner.kind {
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// ensure "if let" compatible match structure
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match *source {
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MatchSource::Normal | MatchSource::IfLetDesugar { .. } => {
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if arms.len() == 2
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&& arms[0].guard.is_none()
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&& arms[1].guard.is_none()
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&& is_simple_break_expr(&arms[1].body)
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{
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if in_external_macro(cx.sess(), expr.span) {
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return;
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}
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// NOTE: we used to build a body here instead of using
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// ellipsis, this was removed because:
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// 1) it was ugly with big bodies;
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// 2) it was not indented properly;
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// 3) it wasn’t very smart (see #675).
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let mut applicability = Applicability::HasPlaceholders;
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span_lint_and_sugg(
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cx,
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WHILE_LET_LOOP,
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expr.span,
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"this loop could be written as a `while let` loop",
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"try",
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format!(
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"while let {} = {} {{ .. }}",
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snippet_with_applicability(cx, arms[0].pat.span, "..", &mut applicability),
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snippet_with_applicability(cx, matchexpr.span, "..", &mut applicability),
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),
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applicability,
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);
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}
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},
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_ => (),
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}
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}
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}
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while_let_loop::check_while_let_loop(cx, expr, block);
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}
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while_let_on_iterator::check_while_let_on_iterator(cx, expr);
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@ -709,39 +666,3 @@ impl std::ops::Sub<&MinifyingSugg<'static>> for MinifyingSugg<'static> {
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}
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}
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}
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/// If a block begins with a statement (possibly a `let` binding) and has an
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/// expression, return it.
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fn extract_expr_from_first_stmt<'tcx>(block: &Block<'tcx>) -> Option<&'tcx Expr<'tcx>> {
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if block.stmts.is_empty() {
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return None;
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}
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if let StmtKind::Local(ref local) = block.stmts[0].kind {
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local.init //.map(|expr| expr)
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} else {
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None
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}
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}
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/// If a block begins with an expression (with or without semicolon), return it.
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fn extract_first_expr<'tcx>(block: &Block<'tcx>) -> Option<&'tcx Expr<'tcx>> {
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match block.expr {
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Some(ref expr) if block.stmts.is_empty() => Some(expr),
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None if !block.stmts.is_empty() => match block.stmts[0].kind {
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StmtKind::Expr(ref expr) | StmtKind::Semi(ref expr) => Some(expr),
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StmtKind::Local(..) | StmtKind::Item(..) => None,
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},
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_ => None,
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}
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}
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/// Returns `true` if expr contains a single break expr without destination label
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/// and
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/// passed expression. The expression may be within a block.
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fn is_simple_break_expr(expr: &Expr<'_>) -> bool {
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match expr.kind {
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ExprKind::Break(dest, ref passed_expr) if dest.label.is_none() && passed_expr.is_none() => true,
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ExprKind::Block(ref b, _) => extract_first_expr(b).map_or(false, |subexpr| is_simple_break_expr(subexpr)),
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_ => false,
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}
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}
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87
clippy_lints/src/loops/while_let_loop.rs
Normal file
87
clippy_lints/src/loops/while_let_loop.rs
Normal file
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@ -0,0 +1,87 @@
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use super::WHILE_LET_LOOP;
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use crate::utils::{snippet_with_applicability, span_lint_and_sugg};
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use rustc_errors::Applicability;
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use rustc_hir::{Block, Expr, ExprKind, MatchSource, StmtKind};
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use rustc_lint::{LateContext, LintContext};
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use rustc_middle::lint::in_external_macro;
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pub(super) fn check_while_let_loop(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, loop_block: &'tcx Block<'_>) {
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// extract the expression from the first statement (if any) in a block
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let inner_stmt_expr = extract_expr_from_first_stmt(loop_block);
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// or extract the first expression (if any) from the block
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if let Some(inner) = inner_stmt_expr.or_else(|| extract_first_expr(loop_block)) {
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if let ExprKind::Match(ref matchexpr, ref arms, ref source) = inner.kind {
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// ensure "if let" compatible match structure
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match *source {
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MatchSource::Normal | MatchSource::IfLetDesugar { .. } => {
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if arms.len() == 2
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&& arms[0].guard.is_none()
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&& arms[1].guard.is_none()
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&& is_simple_break_expr(&arms[1].body)
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{
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if in_external_macro(cx.sess(), expr.span) {
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return;
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}
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// NOTE: we used to build a body here instead of using
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// ellipsis, this was removed because:
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// 1) it was ugly with big bodies;
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// 2) it was not indented properly;
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// 3) it wasn’t very smart (see #675).
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let mut applicability = Applicability::HasPlaceholders;
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span_lint_and_sugg(
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cx,
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WHILE_LET_LOOP,
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expr.span,
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"this loop could be written as a `while let` loop",
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"try",
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format!(
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"while let {} = {} {{ .. }}",
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snippet_with_applicability(cx, arms[0].pat.span, "..", &mut applicability),
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snippet_with_applicability(cx, matchexpr.span, "..", &mut applicability),
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),
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applicability,
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);
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}
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},
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_ => (),
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}
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}
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}
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}
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/// If a block begins with a statement (possibly a `let` binding) and has an
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/// expression, return it.
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fn extract_expr_from_first_stmt<'tcx>(block: &Block<'tcx>) -> Option<&'tcx Expr<'tcx>> {
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if block.stmts.is_empty() {
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return None;
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}
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if let StmtKind::Local(ref local) = block.stmts[0].kind {
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local.init //.map(|expr| expr)
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} else {
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None
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}
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}
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/// If a block begins with an expression (with or without semicolon), return it.
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fn extract_first_expr<'tcx>(block: &Block<'tcx>) -> Option<&'tcx Expr<'tcx>> {
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match block.expr {
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Some(ref expr) if block.stmts.is_empty() => Some(expr),
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None if !block.stmts.is_empty() => match block.stmts[0].kind {
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StmtKind::Expr(ref expr) | StmtKind::Semi(ref expr) => Some(expr),
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StmtKind::Local(..) | StmtKind::Item(..) => None,
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},
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_ => None,
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}
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}
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/// Returns `true` if expr contains a single break expr without destination label
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/// and
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/// passed expression. The expression may be within a block.
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fn is_simple_break_expr(expr: &Expr<'_>) -> bool {
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match expr.kind {
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ExprKind::Break(dest, ref passed_expr) if dest.label.is_none() && passed_expr.is_none() => true,
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ExprKind::Block(ref b, _) => extract_first_expr(b).map_or(false, |subexpr| is_simple_break_expr(subexpr)),
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_ => false,
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}
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}
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