Fix clippy warnings in example solutions (#1747)

Author: senekor

docs/archived/exercise-concepts/luhn.md

@@ -47,8 +47,8 @@ Canonical
 
 ```rust
 pub fn is_valid(candidate: &str) -> bool {
-    if candidate.chars().filter(|c| c.is_digit(10)).take(2).count() <= 1
-        || candidate.chars().any(|c| !c.is_digit(10) && c != ' ')
+    if candidate.chars().filter(|c| c.is_ascii_digit()).take(2).count() <= 1
+        || candidate.chars().any(|c| !c.is_ascii_digit() && c != ' ')
     {
         return false;
     }

exercises/concept/csv-builder/.meta/exemplar.rs

@@ -16,9 +16,9 @@ impl CsvRecordBuilder {
             self.content.push(',');
         }
 
-        if val.contains(",") || val.contains(r#"""#) || val.contains("\n") {
+        if val.contains(',') || val.contains('"') || val.contains('\n') {
             self.content.push('"');
-            self.content.push_str(&val.replace(r#"""#, r#""""#));
+            self.content.push_str(&val.replace('"', r#""""#));
             self.content.push('"');
         } else {
             self.content.push_str(val);
@@ -30,3 +30,9 @@ impl CsvRecordBuilder {
         self.content
     }
 }
+
+impl Default for CsvRecordBuilder {
+    fn default() -> Self {
+        Self::new()
+    }
+}

exercises/practice/acronym/.meta/example.rs

@@ -1,7 +1,7 @@
 pub fn abbreviate(phrase: &str) -> String {
     phrase
         .split(|c: char| c.is_whitespace() || (c != '\'' && !c.is_alphanumeric()))
-        .flat_map(|word| split_camel(word))
+        .flat_map(split_camel)
         .filter_map(|word| word.chars().next())
         .collect::<String>()
         .to_uppercase()

exercises/practice/affine-cipher/.meta/example.rs

@@ -43,7 +43,7 @@ pub fn decode(ciphertext: &str, a: i32, b: i32) -> Result<String, AffineCipherEr
 /// Encodes a single char with the key (`a`, `b`). The key is assumed to be valid (i.e. `a` should
 /// be coprime to 26).
 fn encode_char(ch: char, a: i32, b: i32) -> char {
-    if ch.is_digit(10) {
+    if ch.is_ascii_digit() {
         ch
     } else {
         let index = (ch as i32) - ('a' as i32);
@@ -54,7 +54,7 @@ fn encode_char(ch: char, a: i32, b: i32) -> char {
 
 /// Decodes a single char using `inv` (the modular multiplicative inverse of `a`) and `b`.
 fn decode_char(ch: char, inv: i32, b: i32) -> char {
-    if ch.is_digit(10) {
+    if ch.is_ascii_digit() {
         ch
     } else {
         let index = (ch as i32) - ('a' as i32);
@@ -82,7 +82,7 @@ fn modular_multiplicative_inverse(a: i32) -> Option<i32> {
     if rs.0 == 1 {
         // ts.0 gives a number such that (s * 26 + t * a) % 26 == 1. Since (s * 26) % 26 == 0,
         // we can further reduce this to (t * a) % 26 == 1. In other words, t is the MMI of a.
-        Some(ts.0 as i32)
+        Some(ts.0)
     } else {
         None
     }

exercises/practice/atbash-cipher/.meta/example.rs

@@ -3,7 +3,7 @@ fn ascii(ch: char) -> u8 {
 }
 
 fn get_transpose(ch: char) -> char {
-    if ch.is_digit(10) {
+    if ch.is_ascii_digit() {
         ch
     } else {
         (ascii('z') - ascii(ch) + ascii('a')) as char

exercises/practice/book-store/.meta/example.rs

@@ -3,7 +3,6 @@ use std::cmp::Ordering;
 use std::collections::hash_map::DefaultHasher;
 use std::collections::{BTreeSet, HashSet};
 use std::hash::{Hash, Hasher};
-use std::mem;
 
 type Book = u32;
 type Price = u32;
@@ -125,7 +124,7 @@ impl Iterator for DecomposeGroups {
         //    then move the last item from the most populous group into a new group, alone,
         //    and return
         let return_value = self.next.clone();
-        if let Some(groups) = mem::replace(&mut self.next, None) {
+        if let Some(groups) = self.next.take() {
             if !(groups.is_empty() || groups.iter().all(|g| g.0.borrow().len() == 1)) {
                 let mut hypothetical;
                 for mpg_book in groups[0].0.borrow().iter() {
@@ -169,7 +168,7 @@ impl DecomposeGroups {
         let mut book_groups = Vec::new();
         'nextbook: for book in books {
             for Group(book_group) in book_groups.iter() {
-                if !book_group.borrow().contains(&book) {
+                if !book_group.borrow().contains(book) {
                     book_group.borrow_mut().insert(*book);
                     continue 'nextbook;
                 }

exercises/practice/bowling/.meta/example.rs

@@ -43,7 +43,7 @@ impl Frame {
             return self.bonus_score() <= 10;
         }
 
-        if let Some(first) = self.bonus.get(0) {
+        if let Some(first) = self.bonus.first() {
             if *first == 10 {
                 self.bonus_score() <= 20
             } else {
@@ -139,3 +139,9 @@ impl BowlingGame {
         self.frames.len() == 10 && self.frames.iter().all(|f| f.is_complete())
     }
 }
+
+impl Default for BowlingGame {
+    fn default() -> Self {
+        Self::new()
+    }
+}

exercises/practice/custom-set/.meta/example.rs

@@ -5,8 +5,8 @@ pub struct CustomSet<T> {
 
 impl<T: Ord + Clone> PartialEq for CustomSet<T> {
     fn eq(&self, other: &Self) -> bool {
-        self.collection.iter().all(|x| other.contains(&x))
-            && other.collection.iter().all(|x| self.contains(&x))
+        self.collection.iter().all(|x| other.contains(x))
+            && other.collection.iter().all(|x| self.contains(x))
     }
 }
 

exercises/practice/decimal/.meta/Cargo-example.toml

@@ -4,5 +4,5 @@ name = "decimal"
 version = "0.1.0"
 
 [dependencies]
-num-bigint = "0.1.40"
-num-traits = "0.1.40"
+num-bigint = "0.4.4"
+num-traits = "0.2.16"

exercises/practice/decimal/.meta/example.rs

@@ -63,7 +63,7 @@ impl Decimal {
     fn equalize_precision(one: &mut Decimal, two: &mut Decimal) {
         fn expand(lower_precision: &mut Decimal, higher_precision: &Decimal) {
             let precision_difference =
-                (higher_precision.decimal_index - lower_precision.decimal_index) as usize;
+                higher_precision.decimal_index - lower_precision.decimal_index;
 
             lower_precision.digits =
                 &lower_precision.digits * pow(BigInt::from(10_usize), precision_difference);
@@ -102,7 +102,9 @@ macro_rules! auto_impl_decimal_ops {
             fn $func_name(mut self, mut rhs: Self) -> Self {
                 Decimal::equalize_precision(&mut self, &mut rhs);
                 Decimal::new(
+                    #[allow(clippy::redundant_closure_call)]
                     $digits_operation(self.digits, rhs.digits),
+                    #[allow(clippy::redundant_closure_call)]
                     $index_operation(self.decimal_index, rhs.decimal_index),
                 )
             }
@@ -125,6 +127,7 @@ macro_rules! auto_impl_decimal_cow {
         impl $trait for Decimal {
             fn $func_name(&self, other: &Self) -> $return_type {
                 if self.decimal_index == other.decimal_index {
+                    #[allow(clippy::redundant_closure_call)]
                     $digits_operation(&self.digits, &other.digits)
                 } else {
                     // if we're here, the decimal indexes are unmatched.