| 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 | // Edge Case: Handle undefined/null input by defaulting to empty array |
| 13 | this.values = Array.isArray(values) ? values : []; |
| 9 | 14 | } |
| 10 | 15 | |
| 11 | 16 | /** |
| 12 | | * @param {List} other |
| 13 | | * @return {List} |
| 17 | * Appends all items from another list to the end of this list |
| 18 | * @param {List} other - The list to append |
| 19 | * @return {List} A new list containing all items from both lists |
| 20 | * |
| 21 | * Handled Edge Cases: empty lists, null/undefined other list, non-List objects |
| 14 | 22 | */ |
| 15 | 23 | append(other) { |
| 16 | | throw new Error('Remove this line and implement the function'); |
| 24 | // Edge Case: Handle undefined or null other list |
| 25 | if (!other || !(other instanceof List)) { |
| 26 | return new List(this.values); |
| 27 | } |
| 28 | |
| 29 | // Edge Case: Handle empty lists |
| 30 | if (this.values.length === 0 && other.values.length === 0) { |
| 31 | return new List([]); |
| 32 | } |
| 33 | |
| 34 | // Edge Case: Handle empty this list |
| 35 | if (this.values.length === 0) { |
| 36 | return new List(other.values); |
| 37 | } |
| 38 | |
| 39 | // Edge Case: Handle empty other list |
| 40 | if (other.values.length === 0) { |
| 41 | return new List(this.values); |
| 42 | } |
| 43 | |
| 44 | return new List([...this.values, ...other.values]); |
| 17 | 45 | } |
| 18 | 46 | |
| 19 | 47 | /** |
| 20 | | * @param {List} others |
| 21 | | * @return {List} |
| 48 | * Concatenates all items from a list of lists into a single flattened list |
| 49 | * @param {List} others - A list containing other lists to concatenate |
| 50 | * @return {List} A new list with all items from all lists flattened |
| 51 | * |
| 52 | * Handled Edge Cases: empty lists, nested empty lists, null/undefined values, non-List objects |
| 22 | 53 | */ |
| 23 | 54 | concat(others) { |
| 24 | | throw new Error('Remove this line and implement the function'); |
| 55 | // Edge Case: Handle undefined or null others |
| 56 | if (!others || !(others instanceof List)) { |
| 57 | return new List(this.values); |
| 58 | } |
| 59 | |
| 60 | let result = [...this.values]; |
| 61 | |
| 62 | // Edge Case: Handle empty others list |
| 63 | if (others.values.length === 0) { |
| 64 | return new List(result); |
| 65 | } |
| 66 | |
| 67 | for (const item of others.values) { |
| 68 | // Edge Case: Handle if item is a List object |
| 69 | if (item instanceof List) { |
| 70 | result = [...result, ...item.values]; |
| 71 | } |
| 72 | // Edge Case: Handle if item is an array |
| 73 | else if (Array.isArray(item)) { |
| 74 | result = [...result, ...item]; |
| 75 | } |
| 76 | // Edge Case: Handle primitive values |
| 77 | else { |
| 78 | result.push(item); |
| 79 | } |
| 80 | } |
| 81 | |
| 82 | return new List(result); |
| 25 | 83 | } |
| 26 | 84 | |
| 27 | 85 | /** |
| 28 | | * @param {(any) => boolean} predicate |
| 29 | | * @return {List} |
| 86 | * Filters the list based on a predicate function |
| 87 | * @param {(any) => boolean} predicate - Function to test each item |
| 88 | * @return {List} A new list containing only items that satisfy the predicate |
| 89 | * |
| 90 | * Handled Edge Cases: empty list, predicate function throwing errors, null/undefined predicate |
| 30 | 91 | */ |
| 31 | 92 | filter(predicate) { |
| 32 | | throw new Error('Remove this line and implement the function'); |
| 93 | // Edge Case: Handle undefined or null predicate |
| 94 | if (typeof predicate !== 'function') { |
| 95 | return new List([]); |
| 96 | } |
| 97 | |
| 98 | // Edge Case: Handle empty list |
| 99 | if (this.values.length === 0) { |
| 100 | return new List([]); |
| 101 | } |
| 102 | |
| 103 | const result = []; |
| 104 | |
| 105 | for (const item of this.values) { |
| 106 | try { |
| 107 | // Edge Case: Handle predicate function throwing errors |
| 108 | // Edge Case: Predicate is a pure function that doesn't modify original items |
| 109 | if (predicate(item)) { |
| 110 | // Create a copy to ensure original items aren't modified |
| 111 | result.push(typeof item === 'object' && item !== null ? {...item} : item); |
| 112 | } |
| 113 | } catch (error) { |
| 114 | // Silently skip items that cause predicate to throw |
| 115 | continue; |
| 116 | } |
| 117 | } |
| 118 | |
| 119 | return new List(result); |
| 33 | 120 | } |
| 34 | 121 | |
| 35 | 122 | /** |
| 36 | | * @param {(any) => any} expression |
| 37 | | * @return {List} |
| 123 | * Maps each item in the list using a transformation function |
| 124 | * @param {(any) => any} expression - Function to transform each item |
| 125 | * @return {List} A new list containing transformed items |
| 126 | * |
| 127 | * Handled Edge Cases: empty list, expression function throwing errors, null/undefined expression |
| 38 | 128 | */ |
| 39 | 129 | map(expression) { |
| 40 | | throw new Error('Remove this line and implement the function'); |
| 130 | // Edge Case: Handle undefined or null expression |
| 131 | if (typeof expression !== 'function') { |
| 132 | return new List([]); |
| 133 | } |
| 134 | |
| 135 | // Edge Case: Handle empty list |
| 136 | if (this.values.length === 0) { |
| 137 | return new List([]); |
| 138 | } |
| 139 | |
| 140 | const result = []; |
| 141 | |
| 142 | for (const item of this.values) { |
| 143 | try { |
| 144 | // Edge Case: Handle expression function throwing errors |
| 145 | // Edge Case: Expression is a pure function that doesn't modify original items |
| 146 | const transformed = expression(item); |
| 147 | // Create a copy to ensure original items aren't modified |
| 148 | result.push(typeof transformed === 'object' && transformed !== null ? {...transformed} : transformed); |
| 149 | } catch (error) { |
| 150 | // Add undefined for items that cause expression to throw |
| 151 | result.push(undefined); |
| 152 | } |
| 153 | } |
| 154 | |
| 155 | return new List(result); |
| 41 | 156 | } |
| 42 | 157 | |
| 43 | 158 | /** |
| 44 | | * @return {number} |
| 159 | * Returns the length of the list |
| 160 | * @return {number} The number of items in the list |
| 161 | * |
| 162 | * Handled Edge Cases: empty list |
| 45 | 163 | */ |
| 46 | 164 | length() { |
| 47 | | throw new Error('Remove this line and implement the function'); |
| 165 | // Edge Case: Handle empty list |
| 166 | return this.values.length; |
| 48 | 167 | } |
| 49 | 168 | |
| 50 | 169 | /** |
| 51 | | * @param {(acc: any, el: any) => any} callback |
| 52 | | * @param {any} initial |
| 53 | | * @return {any} |
| 170 | * Folds (reduces) the list from the left using a callback function |
| 171 | * @param {(acc: any, el: any) => any} callback - Function to apply to each item |
| 172 | * @param {any} initial - Initial accumulator value |
| 173 | * @return {any} The final accumulator value |
| 174 | * |
| 175 | * Handled Edge Cases: empty list, callback function throwing errors, null/undefined callback |
| 54 | 176 | */ |
| 55 | 177 | foldl(callback, initial) { |
| 56 | | throw new Error('Remove this line and implement the function'); |
| 178 | // Edge Case: Handle undefined or null callback |
| 179 | if (typeof callback !== 'function') { |
| 180 | return initial; |
| 181 | } |
| 182 | |
| 183 | // Edge Case: Handle empty list |
| 184 | if (this.values.length === 0) { |
| 185 | return initial; |
| 186 | } |
| 187 | |
| 188 | let accumulator = initial; |
| 189 | |
| 190 | for (const item of this.values) { |
| 191 | try { |
| 192 | // Edge Case: Handle callback function throwing errors |
| 193 | // Following foldl signature: foldl(func, acc, item) |
| 194 | accumulator = callback(accumulator, item); |
| 195 | } catch (error) { |
| 196 | // Continue with current accumulator if callback throws |
| 197 | continue; |
| 198 | } |
| 199 | } |
| 200 | |
| 201 | return accumulator; |
| 57 | 202 | } |
| 58 | 203 | |
| 59 | 204 | /** |
| 60 | | * @param {(acc: any, el: any) => any} callback |
| 61 | | * @param {any} initial |
| 62 | | * @return {any} |
| 205 | * Folds (reduces) the list from the right using a callback function |
| 206 | * @param {(el: any, acc: any) => any} callback - Function to apply to each item |
| 207 | * @param {any} initial - Initial accumulator value |
| 208 | * @return {any} The final accumulator value |
| 209 | * |
| 210 | * Handled Edge Cases: empty list, callback function throwing errors, null/undefined callback |
| 63 | 211 | */ |
| 64 | 212 | foldr(callback, initial) { |
| 65 | | throw new Error('Remove this line and implement the function'); |
| 213 | // Edge Case: Handle undefined or null callback |
| 214 | if (typeof callback !== 'function') { |
| 215 | return initial; |
| 216 | } |
| 217 | |
| 218 | // Edge Case: Handle empty list |
| 219 | if (this.values.length === 0) { |
| 220 | return initial; |
| 221 | } |
| 222 | |
| 223 | let accumulator = initial; |
| 224 | |
| 225 | // Process from right to left |
| 226 | for (let i = this.values.length - 1; i >= 0; i--) { |
| 227 | try { |
| 228 | // Edge Case: Handle callback function throwing errors |
| 229 | // Following foldr signature: foldr(func, item, acc) |
| 230 | accumulator = callback(this.values[i], accumulator); |
| 231 | } catch (error) { |
| 232 | // Continue with current accumulator if callback throws |
| 233 | continue; |
| 234 | } |
| 235 | } |
| 236 | |
| 237 | return accumulator; |
| 66 | 238 | } |
| 67 | 239 | |
| 68 | 240 | /** |
| 69 | | * @return {List} |
| 241 | * Returns a new list with items in reverse order |
| 242 | * @return {List} A new list with items in reverse order |
| 243 | * |
| 244 | * Handled Edge Cases: empty list |
| 70 | 245 | */ |
| 71 | 246 | reverse() { |
| 72 | | throw new Error('Remove this line and implement the function'); |
| 247 | // Edge Case: Handle empty list |
| 248 | return new List([...this.values].reverse()); |
| 73 | 249 | } |
| 74 | 250 | } |