Refactor option handling

Author: jeremystucki

clippy_lints/src/cargo_common_metadata.rs

@@ -44,11 +44,7 @@ fn missing_warning(cx: &EarlyContext<'_>, package: &cargo_metadata::Package, fie
 }
 
 fn is_empty_str(value: &Option<String>) -> bool {
-    match value {
-        None => true,
-        Some(value) if value.is_empty() => true,
-        _ => false,
-    }
+    value.as_ref().map_or(true, String::is_empty)
 }
 
 fn is_empty_vec(value: &[String]) -> bool {

clippy_lints/src/dbg_macro.rs

@@ -59,9 +59,6 @@ impl EarlyLintPass for DbgMacro {
 fn tts_span(tts: TokenStream) -> Option<Span> {
     let mut cursor = tts.into_trees();
     let first = cursor.next()?.span();
-    let span = match cursor.last() {
-        Some(tree) => first.to(tree.span()),
-        None => first,
-    };
+    let span = cursor.last().map_or(first, |tree| first.to(tree.span()));
     Some(span)
 }

clippy_lints/src/excessive_precision.rs

@@ -98,17 +98,15 @@ impl ExcessivePrecision {
 /// Ex `1_000_000_000.0`
 /// Ex `1_000_000_000.`
 fn dot_zero_exclusion(s: &str) -> bool {
-    if let Some(after_dec) = s.split('.').nth(1) {
+    s.split('.').nth(1).map_or(false, |after_dec| {
         let mut decpart = after_dec.chars().take_while(|c| *c != 'e' || *c != 'E');
 
         match decpart.next() {
             Some('0') => decpart.count() == 0,
             Some(_) => false,
             None => true,
         }
-    } else {
-        false
-    }
+    })
 }
 
 fn max_digits(fty: FloatTy) -> u32 {

clippy_lints/src/functions.rs

@@ -196,14 +196,8 @@ impl<'a, 'tcx> Functions {
         let mut code_in_line;
 
         // Skip the surrounding function decl.
-        let start_brace_idx = match code_snippet.find('{') {
-            Some(i) => i + 1,
-            None => 0,
-        };
-        let end_brace_idx = match code_snippet.rfind('}') {
-            Some(i) => i,
-            None => code_snippet.len(),
-        };
+        let start_brace_idx = code_snippet.find('{').map_or(0, |i| i + 1);
+        let end_brace_idx = code_snippet.rfind('}').unwrap_or_else(|| code_snippet.len());
         let function_lines = code_snippet[start_brace_idx..end_brace_idx].lines();
 
         for mut line in function_lines {
@@ -223,14 +217,8 @@ impl<'a, 'tcx> Functions {
                         None => break,
                     }
                 } else {
-                    let multi_idx = match line.find("/*") {
-                        Some(i) => i,
-                        None => line.len(),
-                    };
-                    let single_idx = match line.find("//") {
-                        Some(i) => i,
-                        None => line.len(),
-                    };
+                    let multi_idx = line.find("/*").unwrap_or_else(|| line.len());
+                    let single_idx = line.find("//").unwrap_or_else(|| line.len());
                     code_in_line |= multi_idx > 0 && single_idx > 0;
                     // Implies multi_idx is below line.len()
                     if multi_idx < single_idx {

clippy_lints/src/loops.rs

@@ -2003,10 +2003,7 @@ fn extract_first_expr(block: &Block) -> Option<&Expr> {
 fn is_simple_break_expr(expr: &Expr) -> bool {
     match expr.node {
         ExprKind::Break(dest, ref passed_expr) if dest.label.is_none() && passed_expr.is_none() => true,
-        ExprKind::Block(ref b, _) => match extract_first_expr(b) {
-            Some(subexpr) => is_simple_break_expr(subexpr),
-            None => false,
-        },
+        ExprKind::Block(ref b, _) => extract_first_expr(b).map_or(false, |subexpr| is_simple_break_expr(subexpr)),
         _ => false,
     }
 }

clippy_lints/src/methods/mod.rs

@@ -2797,10 +2797,9 @@ fn get_error_type<'a>(cx: &LateContext<'_, '_>, ty: Ty<'a>) -> Option<Ty<'a>> {
 
 /// This checks whether a given type is known to implement Debug.
 fn has_debug_impl<'a, 'b>(ty: Ty<'a>, cx: &LateContext<'b, 'a>) -> bool {
-    match cx.tcx.get_diagnostic_item(sym::debug_trait) {
-        Some(debug) => implements_trait(cx, ty, debug, &[]),
-        None => false,
-    }
+    cx.tcx
+        .get_diagnostic_item(sym::debug_trait)
+        .map_or(false, |debug| implements_trait(cx, ty, debug, &[]))
 }
 
 enum Convention {

clippy_lints/src/methods/unnecessary_filter_map.rs

@@ -18,10 +18,8 @@ pub(super) fn lint(cx: &LateContext<'_, '_>, expr: &hir::Expr, args: &[hir::Expr
     if let hir::ExprKind::Closure(_, _, body_id, ..) = args[1].node {
         let body = cx.tcx.hir().body(body_id);
         let arg_id = body.params[0].pat.hir_id;
-        let mutates_arg = match mutated_variables(&body.value, cx) {
-            Some(used_mutably) => used_mutably.contains(&arg_id),
-            None => true,
-        };
+        let mutates_arg =
+            mutated_variables(&body.value, cx).map_or(true, |used_mutably| used_mutably.contains(&arg_id));
 
         let (mut found_mapping, mut found_filtering) = check_expression(&cx, arg_id, &body.value);
 

clippy_lints/src/no_effect.rs

@@ -63,10 +63,7 @@ fn has_no_effect(cx: &LateContext<'_, '_>, expr: &Expr) -> bool {
         ExprKind::Struct(_, ref fields, ref base) => {
             !has_drop(cx, cx.tables.expr_ty(expr))
                 && fields.iter().all(|field| has_no_effect(cx, &field.expr))
-                && match *base {
-                    Some(ref base) => has_no_effect(cx, base),
-                    None => true,
-                }
+                && base.as_ref().map_or(true, |base| has_no_effect(cx, base))
         },
         ExprKind::Call(ref callee, ref args) => {
             if let ExprKind::Path(ref qpath) = callee.node {
@@ -82,12 +79,7 @@ fn has_no_effect(cx: &LateContext<'_, '_>, expr: &Expr) -> bool {
             }
         },
         ExprKind::Block(ref block, _) => {
-            block.stmts.is_empty()
-                && if let Some(ref expr) = block.expr {
-                    has_no_effect(cx, expr)
-                } else {
-                    false
-                }
+            block.stmts.is_empty() && block.expr.as_ref().map_or(false, |expr| has_no_effect(cx, expr))
         },
         _ => false,
     }

clippy_lints/src/utils/mod.rs

@@ -398,10 +398,9 @@ pub fn method_chain_args<'a>(expr: &'a Expr, methods: &[&str]) -> Option<Vec<&'a
 
 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
 pub fn is_entrypoint_fn(cx: &LateContext<'_, '_>, def_id: DefId) -> bool {
-    if let Some((entry_fn_def_id, _)) = cx.tcx.entry_fn(LOCAL_CRATE) {
-        return def_id == entry_fn_def_id;
-    }
-    false
+    cx.tcx
+        .entry_fn(LOCAL_CRATE)
+        .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id)
 }
 
 /// Gets the name of the item the expression is in, if available.