| 4 | 4 | // |
| 5 | 5 | |
| 6 | 6 | export class List { |
| 7 | | constructor() { |
| 8 | | throw new Error('Remove this line and implement the function'); |
| 7 | /** |
| 8 | * Creates a new List instance. |
| 9 | * @param {Array} [values=[]] - Initial values for the list. |
| 10 | */ |
| 11 | constructor(values = []) { |
| 12 | this.values = values; |
| 9 | 13 | } |
| 10 | 14 | |
| 11 | 15 | /** |
| 12 | | * @param {List} other |
| 13 | | * @return {List} |
| 16 | * Appends all items from another list to the end of this list. |
| 17 | * @param {List} other - The list to append. |
| 18 | * @return {List} A new list containing all items from both lists. |
| 19 | * |
| 20 | * Handled Edge Cases: |
| 21 | * - Appending an empty list to another list |
| 22 | * - Appending a list to an empty list |
| 14 | 23 | */ |
| 15 | 24 | append(other) { |
| 16 | | throw new Error('Remove this line and implement the function'); |
| 25 | // Edge Case: Appending an empty list |
| 26 | if (other.length() === 0) { |
| 27 | return new List(this.values); |
| 28 | } |
| 29 | |
| 30 | // Edge Case: Appending to an empty list |
| 31 | if (this.length() === 0) { |
| 32 | return new List(other.values); |
| 33 | } |
| 34 | |
| 35 | return new List([...this.values, ...other.values]); |
| 17 | 36 | } |
| 18 | 37 | |
| 19 | 38 | /** |
| 20 | | * @param {List} others |
| 21 | | * @return {List} |
| 39 | * Concatenates a series of lists into one flattened list. |
| 40 | * @param {List} others - A list containing other lists to concatenate. |
| 41 | * @return {List} A new list with all items from all lists. |
| 42 | * |
| 43 | * Handled Edge Cases: |
| 44 | * - Concatenating with an empty list of lists |
| 45 | * - Concatenating when the input contains empty lists |
| 22 | 46 | */ |
| 23 | 47 | concat(others) { |
| 24 | | throw new Error('Remove this line and implement the function'); |
| 48 | let result = [...this.values]; |
| 49 | |
| 50 | // Edge Case: Concatenating with an empty list of lists |
| 51 | if (others.length() === 0) { |
| 52 | return new List(result); |
| 53 | } |
| 54 | |
| 55 | for (const list of others.values) { |
| 56 | // Edge Case: Handling empty lists in the input |
| 57 | if (list instanceof List) { |
| 58 | result = [...result, ...list.values]; |
| 59 | } |
| 60 | } |
| 61 | |
| 62 | return new List(result); |
| 25 | 63 | } |
| 26 | 64 | |
| 27 | 65 | /** |
| 28 | | * @param {(any) => boolean} predicate |
| 29 | | * @return {List} |
| 66 | * Filters the list based on a predicate function. |
| 67 | * @param {(any) => boolean} predicate - Function to test each item. |
| 68 | * @return {List} A new list containing only items that satisfy the predicate. |
| 69 | * |
| 70 | * Handled Edge Cases: |
| 71 | * - Filtering an empty list |
| 72 | * - Predicate that matches no items |
| 73 | * - Predicate that matches all items |
| 30 | 74 | */ |
| 31 | 75 | filter(predicate) { |
| 32 | | throw new Error('Remove this line and implement the function'); |
| 76 | // Edge Case: Filtering an empty list |
| 77 | if (this.length() === 0) { |
| 78 | return new List([]); |
| 79 | } |
| 80 | |
| 81 | const result = []; |
| 82 | for (const item of this.values) { |
| 83 | if (predicate(item)) { |
| 84 | result.push(item); |
| 85 | } |
| 86 | } |
| 87 | |
| 88 | // Edge Case: Predicate matches no items or all items (implicitly handled) |
| 89 | return new List(result); |
| 33 | 90 | } |
| 34 | 91 | |
| 35 | 92 | /** |
| 36 | | * @param {(any) => any} expression |
| 37 | | * @return {List} |
| 93 | * Transforms each item in the list using a provided function. |
| 94 | * @param {(any) => any} expression - Function to apply to each item. |
| 95 | * @return {List} A new list with transformed items. |
| 96 | * |
| 97 | * Handled Edge Cases: |
| 98 | * - Mapping over an empty list |
| 38 | 99 | */ |
| 39 | 100 | map(expression) { |
| 40 | | throw new Error('Remove this line and implement the function'); |
| 101 | // Edge Case: Mapping over an empty list |
| 102 | if (this.length() === 0) { |
| 103 | return new List([]); |
| 104 | } |
| 105 | |
| 106 | const result = []; |
| 107 | for (const item of this.values) { |
| 108 | result.push(expression(item)); |
| 109 | } |
| 110 | |
| 111 | return new List(result); |
| 41 | 112 | } |
| 42 | 113 | |
| 43 | 114 | /** |
| 44 | | * @return {number} |
| 115 | * Returns the number of items in the list. |
| 116 | * @return {number} The length of the list. |
| 117 | * |
| 118 | * Handled Edge Cases: |
| 119 | * - Getting length of an empty list |
| 45 | 120 | */ |
| 46 | 121 | length() { |
| 47 | | throw new Error('Remove this line and implement the function'); |
| 122 | // Edge Case: Empty list |
| 123 | let count = 0; |
| 124 | for (const _ of this.values) { |
| 125 | count++; |
| 126 | } |
| 127 | return count; |
| 48 | 128 | } |
| 49 | 129 | |
| 50 | 130 | /** |
| 51 | | * @param {(acc: any, el: any) => any} callback |
| 52 | | * @param {any} initial |
| 53 | | * @return {any} |
| 131 | * Folds (reduces) the list from the left using a callback function. |
| 132 | * @param {(acc: any, el: any) => any} callback - Function to apply to each item. |
| 133 | * @param {any} initial - Initial accumulator value. |
| 134 | * @return {any} The final accumulator value. |
| 135 | * |
| 136 | * Handled Edge Cases: |
| 137 | * - Folding an empty list (returns initial value) |
| 54 | 138 | */ |
| 55 | 139 | foldl(callback, initial) { |
| 56 | | throw new Error('Remove this line and implement the function'); |
| 140 | // Edge Case: Folding an empty list |
| 141 | if (this.length() === 0) { |
| 142 | return initial; |
| 143 | } |
| 144 | |
| 145 | let accumulator = initial; |
| 146 | for (const item of this.values) { |
| 147 | accumulator = callback(accumulator, item); |
| 148 | } |
| 149 | |
| 150 | return accumulator; |
| 57 | 151 | } |
| 58 | 152 | |
| 59 | 153 | /** |
| 60 | | * @param {(acc: any, el: any) => any} callback |
| 61 | | * @param {any} initial |
| 62 | | * @return {any} |
| 154 | * Folds (reduces) the list from the right using a callback function. |
| 155 | * @param {(el: any, acc: any) => any} callback - Function to apply to each item. |
| 156 | * @param {any} initial - Initial accumulator value. |
| 157 | * @return {any} The final accumulator value. |
| 158 | * |
| 159 | * Handled Edge Cases: |
| 160 | * - Folding an empty list (returns initial value) |
| 63 | 161 | */ |
| 64 | 162 | foldr(callback, initial) { |
| 65 | | throw new Error('Remove this line and implement the function'); |
| 163 | // Edge Case: Folding an empty list |
| 164 | if (this.length() === 0) { |
| 165 | return initial; |
| 166 | } |
| 167 | |
| 168 | let accumulator = initial; |
| 169 | // Process items from right to left |
| 170 | for (let i = this.values.length - 1; i >= 0; i--) { |
| 171 | accumulator = callback(this.values[i], accumulator); |
| 172 | } |
| 173 | |
| 174 | return accumulator; |
| 66 | 175 | } |
| 67 | 176 | |
| 68 | 177 | /** |
| 69 | | * @return {List} |
| 178 | * Reverses the order of items in the list. |
| 179 | * @return {List} A new list with items in reversed order. |
| 180 | * |
| 181 | * Handled Edge Cases: |
| 182 | * - Reversing an empty list |
| 70 | 183 | */ |
| 71 | 184 | reverse() { |
| 72 | | throw new Error('Remove this line and implement the function'); |
| 185 | // Edge Case: Reversing an empty list |
| 186 | if (this.length() === 0) { |
| 187 | return new List([]); |
| 188 | } |
| 189 | |
| 190 | const result = []; |
| 191 | for (let i = this.values.length - 1; i >= 0; i--) { |
| 192 | result.push(this.values[i]); |
| 193 | } |
| 194 | |
| 195 | return new List(result); |
| 73 | 196 | } |
| 74 | 197 | } |