| 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 |
| 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 | * - When other list is empty |
| 22 | * - When this list is empty |
| 23 | * - When both lists are empty |
| 14 | 24 | */ |
| 15 | 25 | append(other) { |
| 16 | | throw new Error('Remove this line and implement the function'); |
| 26 | // Edge Case: Handle when other list is not a List instance |
| 27 | if (!(other instanceof List)) { |
| 28 | throw new Error('Argument must be a List'); |
| 29 | } |
| 30 | |
| 31 | return new List(this.values.concat(other.values)); |
| 17 | 32 | } |
| 18 | 33 | |
| 19 | 34 | /** |
| 20 | | * @param {List} others |
| 21 | | * @return {List} |
| 35 | * Concatenates a list of lists into one flattened list |
| 36 | * @param {List} others - A list containing other lists to concatenate |
| 37 | * @return {List} A new List with all items from all lists flattened |
| 38 | * |
| 39 | * Handled Edge Cases: |
| 40 | * - When others list is empty |
| 41 | * - When some contained lists are empty |
| 42 | * - When all contained lists are empty |
| 22 | 43 | */ |
| 23 | 44 | concat(others) { |
| 24 | | throw new Error('Remove this line and implement the function'); |
| 45 | // Edge Case: Handle when others is not a List instance |
| 46 | if (!(others instanceof List)) { |
| 47 | throw new Error('Argument must be a List'); |
| 48 | } |
| 49 | |
| 50 | let result = this.values.slice(); // Start with a copy of current list |
| 51 | |
| 52 | // Edge Case: Handle when others list is empty |
| 53 | if (others.length() === 0) { |
| 54 | return new List(result); |
| 55 | } |
| 56 | |
| 57 | for (let i = 0; i < others.length(); i++) { |
| 58 | const item = others.values[i]; |
| 59 | // Edge Case: Handle when item is not a List instance |
| 60 | if (item instanceof List) { |
| 61 | result = result.concat(item.values); |
| 62 | } else { |
| 63 | // If item is not a List, we treat it as a single element |
| 64 | result.push(item); |
| 65 | } |
| 66 | } |
| 67 | |
| 68 | return new List(result); |
| 25 | 69 | } |
| 26 | 70 | |
| 27 | 71 | /** |
| 28 | | * @param {(any) => boolean} predicate |
| 29 | | * @return {List} |
| 72 | * Filters the list based on a predicate function |
| 73 | * @param {Function} predicate - Function that returns true for items to keep |
| 74 | * @return {List} A new List containing only items for which predicate returned true |
| 75 | * |
| 76 | * Handled Edge Cases: |
| 77 | * - When list is empty |
| 78 | * - When no items match the predicate |
| 79 | * - When all items match the predicate |
| 30 | 80 | */ |
| 31 | 81 | filter(predicate) { |
| 32 | | throw new Error('Remove this line and implement the function'); |
| 82 | // Edge Case: Handle when predicate is not a function |
| 83 | if (typeof predicate !== 'function') { |
| 84 | throw new Error('Predicate must be a function'); |
| 85 | } |
| 86 | |
| 87 | const result = []; |
| 88 | |
| 89 | // Edge Case: Handle when list is empty |
| 90 | if (this.length() === 0) { |
| 91 | return new List(result); |
| 92 | } |
| 93 | |
| 94 | for (let i = 0; i < this.values.length; i++) { |
| 95 | if (predicate(this.values[i])) { |
| 96 | result.push(this.values[i]); |
| 97 | } |
| 98 | } |
| 99 | |
| 100 | return new List(result); |
| 33 | 101 | } |
| 34 | 102 | |
| 35 | 103 | /** |
| 36 | | * @param {(any) => any} expression |
| 37 | | * @return {List} |
| 104 | * Transforms each item in the list using a provided function |
| 105 | * @param {Function} expression - Function to apply to each item |
| 106 | * @return {List} A new List containing transformed items |
| 107 | * |
| 108 | * Handled Edge Cases: |
| 109 | * - When list is empty |
| 110 | * - When expression function modifies types of elements |
| 38 | 111 | */ |
| 39 | 112 | map(expression) { |
| 40 | | throw new Error('Remove this line and implement the function'); |
| 113 | // Edge Case: Handle when expression is not a function |
| 114 | if (typeof expression !== 'function') { |
| 115 | throw new Error('Expression must be a function'); |
| 116 | } |
| 117 | |
| 118 | const result = []; |
| 119 | |
| 120 | // Edge Case: Handle when list is empty |
| 121 | if (this.length() === 0) { |
| 122 | return new List(result); |
| 123 | } |
| 124 | |
| 125 | for (let i = 0; i < this.values.length; i++) { |
| 126 | result.push(expression(this.values[i])); |
| 127 | } |
| 128 | |
| 129 | return new List(result); |
| 41 | 130 | } |
| 42 | 131 | |
| 43 | 132 | /** |
| 44 | | * @return {number} |
| 133 | * Returns the number of items in the list |
| 134 | * @return {number} The count of items in the list |
| 135 | * |
| 136 | * Handled Edge Cases: |
| 137 | * - When list is empty (returns 0) |
| 45 | 138 | */ |
| 46 | 139 | length() { |
| 47 | | throw new Error('Remove this line and implement the function'); |
| 140 | let count = 0; |
| 141 | |
| 142 | // Edge Case: Handle when list is empty |
| 143 | if (this.values === undefined || this.values === null) { |
| 144 | return count; |
| 145 | } |
| 146 | |
| 147 | for (let i = 0; i < this.values.length; i++) { |
| 148 | count++; |
| 149 | } |
| 150 | |
| 151 | return count; |
| 48 | 152 | } |
| 49 | 153 | |
| 50 | 154 | /** |
| 51 | | * @param {(acc: any, el: any) => any} callback |
| 52 | | * @param {any} initial |
| 53 | | * @return {any} |
| 155 | * Folds (reduces) the list from left to right using a callback function |
| 156 | * @param {Function} callback - Function to apply to each item with accumulator |
| 157 | * @param {any} initial - Initial value for the accumulator |
| 158 | * @return {any} The final accumulated value |
| 159 | * |
| 160 | * Handled Edge Cases: |
| 161 | * - When list is empty (returns initial value) |
| 162 | * - When callback is not a function |
| 54 | 163 | */ |
| 55 | 164 | foldl(callback, initial) { |
| 56 | | throw new Error('Remove this line and implement the function'); |
| 165 | // Edge Case: Handle when callback is not a function |
| 166 | if (typeof callback !== 'function') { |
| 167 | throw new Error('Callback must be a function'); |
| 168 | } |
| 169 | |
| 170 | let accumulator = initial; |
| 171 | |
| 172 | // Edge Case: Handle when list is empty |
| 173 | if (this.length() === 0) { |
| 174 | return accumulator; |
| 175 | } |
| 176 | |
| 177 | for (let i = 0; i < this.values.length; i++) { |
| 178 | accumulator = callback(accumulator, this.values[i]); |
| 179 | } |
| 180 | |
| 181 | return accumulator; |
| 57 | 182 | } |
| 58 | 183 | |
| 59 | 184 | /** |
| 60 | | * @param {(acc: any, el: any) => any} callback |
| 61 | | * @param {any} initial |
| 62 | | * @return {any} |
| 185 | * Folds (reduces) the list from right to left using a callback function |
| 186 | * @param {Function} callback - Function to apply to each item with accumulator |
| 187 | * @param {any} initial - Initial value for the accumulator |
| 188 | * @return {any} The final accumulated value |
| 189 | * |
| 190 | * Handled Edge Cases: |
| 191 | * - When list is empty (returns initial value) |
| 192 | * - When callback is not a function |
| 63 | 193 | */ |
| 64 | 194 | foldr(callback, initial) { |
| 65 | | throw new Error('Remove this line and implement the function'); |
| 195 | // Edge Case: Handle when callback is not a function |
| 196 | if (typeof callback !== 'function') { |
| 197 | throw new Error('Callback must be a function'); |
| 198 | } |
| 199 | |
| 200 | let accumulator = initial; |
| 201 | |
| 202 | // Edge Case: Handle when list is empty |
| 203 | if (this.length() === 0) { |
| 204 | return accumulator; |
| 205 | } |
| 206 | |
| 207 | // Process from right to left |
| 208 | for (let i = this.values.length - 1; i >= 0; i--) { |
| 209 | accumulator = callback(accumulator, this.values[i]); |
| 210 | } |
| 211 | |
| 212 | return accumulator; |
| 66 | 213 | } |
| 67 | 214 | |
| 68 | 215 | /** |
| 69 | | * @return {List} |
| 216 | * Returns a new list with items in reverse order |
| 217 | * @return {List} A new List with items in reverse order |
| 218 | * |
| 219 | * Handled Edge Cases: |
| 220 | * - When list is empty |
| 221 | * - When list has only one item |
| 70 | 222 | */ |
| 71 | 223 | reverse() { |
| 72 | | throw new Error('Remove this line and implement the function'); |
| 224 | const result = []; |
| 225 | |
| 226 | // Edge Case: Handle when list is empty |
| 227 | if (this.length() === 0) { |
| 228 | return new List(result); |
| 229 | } |
| 230 | |
| 231 | // Edge Case: Handle when list has only one item |
| 232 | if (this.length() === 1) { |
| 233 | return new List([this.values[0]]); |
| 234 | } |
| 235 | |
| 236 | for (let i = this.values.length - 1; i >= 0; i--) { |
| 237 | result.push(this.values[i]); |
| 238 | } |
| 239 | |
| 240 | return new List(result); |
| 73 | 241 | } |
| 74 | 242 | } |