| 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 another list to this list. |
| 17 | * @param {List} other - The list to append. |
| 18 | * @return {List} A new list containing elements from both lists. |
| 19 | * |
| 20 | * Handled Edge Cases: Empty lists, null/undefined other list |
| 14 | 21 | */ |
| 15 | 22 | append(other) { |
| 16 | | throw new Error('Remove this line and implement the function'); |
| 23 | // Edge Case: If other is not a List instance, we treat it as an empty list |
| 24 | if (!(other instanceof List)) { |
| 25 | other = new List(); |
| 26 | } |
| 27 | |
| 28 | // Edge Case: Handle empty lists |
| 29 | if (this.values.length === 0 && other.values.length === 0) { |
| 30 | return new List(); |
| 31 | } |
| 32 | |
| 33 | if (this.values.length === 0) { |
| 34 | return new List(other.values); |
| 35 | } |
| 36 | |
| 37 | if (other.values.length === 0) { |
| 38 | return new List(this.values); |
| 39 | } |
| 40 | |
| 41 | return new List([...this.values, ...other.values]); |
| 17 | 42 | } |
| 18 | 43 | |
| 19 | 44 | /** |
| 20 | | * @param {List} others |
| 21 | | * @return {List} |
| 45 | * Concatenates multiple lists into one. |
| 46 | * @param {List} others - A list of lists to concatenate. |
| 47 | * @return {List} A new list with all elements flattened. |
| 48 | * |
| 49 | * Handled Edge Cases: Empty lists, nested empty lists |
| 22 | 50 | */ |
| 23 | 51 | concat(others) { |
| 24 | | throw new Error('Remove this line and implement the function'); |
| 52 | // Edge Case: If others is not a List instance, treat as empty list |
| 53 | if (!(others instanceof List)) { |
| 54 | return new List(this.values); |
| 55 | } |
| 56 | |
| 57 | let result = [...this.values]; |
| 58 | |
| 59 | // Edge Case: Handle empty others list |
| 60 | if (others.values.length === 0) { |
| 61 | return new List(result); |
| 62 | } |
| 63 | |
| 64 | for (const item of others.values) { |
| 65 | if (item instanceof List) { |
| 66 | result = [...result, ...item.values]; |
| 67 | } else { |
| 68 | // Edge Case: If item is not a List, add it directly |
| 69 | result.push(item); |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | return new List(result); |
| 25 | 74 | } |
| 26 | 75 | |
| 27 | 76 | /** |
| 28 | | * @param {(any) => boolean} predicate |
| 29 | | * @return {List} |
| 77 | * Filters the list based on a predicate function. |
| 78 | * @param {(any) => boolean} predicate - Function to test each element. |
| 79 | * @return {List} A new list with elements that pass the predicate test. |
| 80 | * |
| 81 | * Handled Edge Cases: Empty list, null/undefined predicate |
| 30 | 82 | */ |
| 31 | 83 | filter(predicate) { |
| 32 | | throw new Error('Remove this line and implement the function'); |
| 84 | // Edge Case: If predicate is not a function, return empty list |
| 85 | if (typeof predicate !== 'function') { |
| 86 | return new List(); |
| 87 | } |
| 88 | |
| 89 | // Edge Case: Handle empty list |
| 90 | if (this.values.length === 0) { |
| 91 | return new List(); |
| 92 | } |
| 93 | |
| 94 | const result = []; |
| 95 | for (const item of this.values) { |
| 96 | if (predicate(item)) { |
| 97 | result.push(item); |
| 98 | } |
| 99 | } |
| 100 | |
| 101 | return new List(result); |
| 33 | 102 | } |
| 34 | 103 | |
| 35 | 104 | /** |
| 36 | | * @param {(any) => any} expression |
| 37 | | * @return {List} |
| 105 | * Maps each element using a provided function. |
| 106 | * @param {(any) => any} expression - Function to transform each element. |
| 107 | * @return {List} A new list with transformed elements. |
| 108 | * |
| 109 | * Handled Edge Cases: Empty list, null/undefined expression |
| 38 | 110 | */ |
| 39 | 111 | map(expression) { |
| 40 | | throw new Error('Remove this line and implement the function'); |
| 112 | // Edge Case: If expression is not a function, return empty list |
| 113 | if (typeof expression !== 'function') { |
| 114 | return new List(); |
| 115 | } |
| 116 | |
| 117 | // Edge Case: Handle empty list |
| 118 | if (this.values.length === 0) { |
| 119 | return new List(); |
| 120 | } |
| 121 | |
| 122 | const result = []; |
| 123 | for (const item of this.values) { |
| 124 | result.push(expression(item)); |
| 125 | } |
| 126 | |
| 127 | return new List(result); |
| 41 | 128 | } |
| 42 | 129 | |
| 43 | 130 | /** |
| 44 | | * @return {number} |
| 131 | * Returns the length of the list. |
| 132 | * @return {number} The number of elements in the list. |
| 133 | * |
| 134 | * Handled Edge Cases: Empty list |
| 45 | 135 | */ |
| 46 | 136 | length() { |
| 47 | | throw new Error('Remove this line and implement the function'); |
| 137 | // Edge Case: Handle empty list |
| 138 | let count = 0; |
| 139 | for (const _ of this.values) { |
| 140 | count++; |
| 141 | } |
| 142 | return count; |
| 48 | 143 | } |
| 49 | 144 | |
| 50 | 145 | /** |
| 51 | | * @param {(acc: any, el: any) => any} callback |
| 52 | | * @param {any} initial |
| 53 | | * @return {any} |
| 146 | * Folds the list from the left using a callback function. |
| 147 | * @param {(acc: any, el: any) => any} callback - Function to apply to each element. |
| 148 | * @param {any} initial - Initial accumulator value. |
| 149 | * @return {any} The final accumulator value. |
| 150 | * |
| 151 | * Handled Edge Cases: Empty list, null/undefined callback |
| 54 | 152 | */ |
| 55 | 153 | foldl(callback, initial) { |
| 56 | | throw new Error('Remove this line and implement the function'); |
| 154 | // Edge Case: If callback is not a function, return initial value |
| 155 | if (typeof callback !== 'function') { |
| 156 | return initial; |
| 157 | } |
| 158 | |
| 159 | // Edge Case: Handle empty list |
| 160 | if (this.values.length === 0) { |
| 161 | return initial; |
| 162 | } |
| 163 | |
| 164 | let accumulator = initial; |
| 165 | for (const item of this.values) { |
| 166 | accumulator = callback(accumulator, item); |
| 167 | } |
| 168 | |
| 169 | return accumulator; |
| 57 | 170 | } |
| 58 | 171 | |
| 59 | 172 | /** |
| 60 | | * @param {(acc: any, el: any) => any} callback |
| 61 | | * @param {any} initial |
| 62 | | * @return {any} |
| 173 | * Folds the list from the right using a callback function. |
| 174 | * @param {(acc: any, el: any) => any} callback - Function to apply to each element. |
| 175 | * @param {any} initial - Initial accumulator value. |
| 176 | * @return {any} The final accumulator value. |
| 177 | * |
| 178 | * Handled Edge Cases: Empty list, null/undefined callback |
| 63 | 179 | */ |
| 64 | 180 | foldr(callback, initial) { |
| 65 | | throw new Error('Remove this line and implement the function'); |
| 181 | // Edge Case: If callback is not a function, return initial value |
| 182 | if (typeof callback !== 'function') { |
| 183 | return initial; |
| 184 | } |
| 185 | |
| 186 | // Edge Case: Handle empty list |
| 187 | if (this.values.length === 0) { |
| 188 | return initial; |
| 189 | } |
| 190 | |
| 191 | let accumulator = initial; |
| 192 | // Process from right to left |
| 193 | for (let i = this.values.length - 1; i >= 0; i--) { |
| 194 | accumulator = callback(accumulator, this.values[i]); |
| 195 | } |
| 196 | |
| 197 | return accumulator; |
| 66 | 198 | } |
| 67 | 199 | |
| 68 | 200 | /** |
| 69 | | * @return {List} |
| 201 | * Reverses the list. |
| 202 | * @return {List} A new list with elements in reverse order. |
| 203 | * |
| 204 | * Handled Edge Cases: Empty list, single element list |
| 70 | 205 | */ |
| 71 | 206 | reverse() { |
| 72 | | throw new Error('Remove this line and implement the function'); |
| 207 | // Edge Case: Handle empty list |
| 208 | if (this.values.length === 0) { |
| 209 | return new List(); |
| 210 | } |
| 211 | |
| 212 | // Edge Case: Handle single element list |
| 213 | if (this.values.length === 1) { |
| 214 | return new List([this.values[0]]); |
| 215 | } |
| 216 | |
| 217 | const result = []; |
| 218 | for (let i = this.values.length - 1; i >= 0; i--) { |
| 219 | result.push(this.values[i]); |
| 220 | } |
| 221 | |
| 222 | return new List(result); |
| 73 | 223 | } |
| 74 | 224 | } |