| 1 | | // |
| 2 | | // This is only a SKELETON file for the 'List Ops' exercise. It's been provided as a |
| 3 | | // convenience to get you started writing code faster. |
| 4 | | // |
| 5 | | |
| 6 | 1 | export class List { |
| 7 | | constructor() { |
| 8 | | throw new Error('Remove this line and implement the function'); |
| 2 | /** |
| 3 | * Creates a new List instance. |
| 4 | * @param {Array} [values=[]] - Initial values for the list. |
| 5 | */ |
| 6 | constructor(values = []) { |
| 7 | this.values = values; |
| 9 | 8 | } |
| 10 | 9 | |
| 11 | 10 | /** |
| 12 | | * @param {List} other |
| 13 | | * @return {List} |
| 11 | * Appends all items from another list to the end of this list. |
| 12 | * @param {List} other - The list to append. |
| 13 | * @return {List} A new List containing all items from both lists. |
| 14 | * Handled Edge Cases: Appending empty lists, appending to empty lists |
| 14 | 15 | */ |
| 15 | 16 | append(other) { |
| 16 | | throw new Error('Remove this line and implement the function'); |
| 17 | // Edge Case: Appending empty lists |
| 18 | if (!other || !other.values) { |
| 19 | return new List(this.values); |
| 20 | } |
| 21 | |
| 22 | const result = []; |
| 23 | for (let i = 0; i < this.values.length; i++) { |
| 24 | result.push(this.values[i]); |
| 25 | } |
| 26 | for (let i = 0; i < other.values.length; i++) { |
| 27 | result.push(other.values[i]); |
| 28 | } |
| 29 | return new List(result); |
| 17 | 30 | } |
| 18 | 31 | |
| 19 | 32 | /** |
| 20 | | * @param {List} others |
| 21 | | * @return {List} |
| 33 | * Concatenates a series of lists into one flattened list. |
| 34 | * @param {List} others - A list containing other lists to concatenate. |
| 35 | * @return {List} A new List with all items from all lists. |
| 36 | * Handled Edge Cases: Concatenating empty lists, concatenating lists with empty sublists |
| 22 | 37 | */ |
| 23 | 38 | concat(others) { |
| 24 | | throw new Error('Remove this line and implement the function'); |
| 39 | // Edge Case: Empty others list |
| 40 | if (!others || !others.values) { |
| 41 | return new List(this.values); |
| 42 | } |
| 43 | |
| 44 | const result = []; |
| 45 | |
| 46 | // Add items from the current list |
| 47 | for (let i = 0; i < this.values.length; i++) { |
| 48 | result.push(this.values[i]); |
| 49 | } |
| 50 | |
| 51 | // Add items from each sublist in others |
| 52 | for (let i = 0; i < others.values.length; i++) { |
| 53 | const sublist = others.values[i]; |
| 54 | // Edge Case: Sublist is not a List instance |
| 55 | if (sublist instanceof List) { |
| 56 | for (let j = 0; j < sublist.values.length; j++) { |
| 57 | result.push(sublist.values[j]); |
| 58 | } |
| 59 | } else { |
| 60 | // If it's not a List, treat it as a single value |
| 61 | result.push(sublist); |
| 62 | } |
| 63 | } |
| 64 | |
| 65 | return new List(result); |
| 25 | 66 | } |
| 26 | 67 | |
| 27 | 68 | /** |
| 28 | | * @param {(any) => boolean} predicate |
| 29 | | * @return {List} |
| 69 | * Filters the list based on a predicate function. |
| 70 | * @param {Function} predicate - Function that returns true for items to keep. |
| 71 | * @return {List} A new List containing only items for which predicate returned true. |
| 72 | * Handled Edge Cases: Empty list, predicate that matches no items, predicate that matches all items |
| 30 | 73 | */ |
| 31 | 74 | filter(predicate) { |
| 32 | | throw new Error('Remove this line and implement the function'); |
| 75 | // Edge Case: Empty list |
| 76 | if (this.values.length === 0) { |
| 77 | return new List([]); |
| 78 | } |
| 79 | |
| 80 | const result = []; |
| 81 | for (let i = 0; i < this.values.length; i++) { |
| 82 | if (predicate(this.values[i])) { |
| 83 | result.push(this.values[i]); |
| 84 | } |
| 85 | } |
| 86 | return new List(result); |
| 33 | 87 | } |
| 34 | 88 | |
| 35 | 89 | /** |
| 36 | | * @param {(any) => any} expression |
| 37 | | * @return {List} |
| 90 | * Applies a function to each item in the list. |
| 91 | * @param {Function} expression - Function to apply to each item. |
| 92 | * @return {List} A new List containing the results of applying the function. |
| 93 | * Handled Edge Cases: Empty list |
| 38 | 94 | */ |
| 39 | 95 | map(expression) { |
| 40 | | throw new Error('Remove this line and implement the function'); |
| 96 | // Edge Case: Empty list |
| 97 | if (this.values.length === 0) { |
| 98 | return new List([]); |
| 99 | } |
| 100 | |
| 101 | const result = []; |
| 102 | for (let i = 0; i < this.values.length; i++) { |
| 103 | result.push(expression(this.values[i])); |
| 104 | } |
| 105 | return new List(result); |
| 41 | 106 | } |
| 42 | 107 | |
| 43 | 108 | /** |
| 44 | | * @return {number} |
| 109 | * Returns the number of items in the list. |
| 110 | * @return {number} The length of the list. |
| 111 | * Handled Edge Cases: Empty list |
| 45 | 112 | */ |
| 46 | 113 | length() { |
| 47 | | throw new Error('Remove this line and implement the function'); |
| 114 | let count = 0; |
| 115 | for (let i = 0; i < this.values.length; i++) { |
| 116 | count++; |
| 117 | } |
| 118 | return count; |
| 48 | 119 | } |
| 49 | 120 | |
| 50 | 121 | /** |
| 51 | | * @param {(acc: any, el: any) => any} callback |
| 52 | | * @param {any} initial |
| 53 | | * @return {any} |
| 122 | * Folds (reduces) the list from the left using a callback function. |
| 123 | * @param {Function} callback - Function to apply to accumulator and each item. |
| 124 | * @param {any} initial - Initial value for the accumulator. |
| 125 | * @return {any} The final accumulator value. |
| 126 | * Handled Edge Cases: Empty list |
| 54 | 127 | */ |
| 55 | 128 | foldl(callback, initial) { |
| 56 | | throw new Error('Remove this line and implement the function'); |
| 129 | let accumulator = initial; |
| 130 | |
| 131 | // Edge Case: Empty list |
| 132 | if (this.values.length === 0) { |
| 133 | return accumulator; |
| 134 | } |
| 135 | |
| 136 | for (let i = 0; i < this.values.length; i++) { |
| 137 | accumulator = callback(accumulator, this.values[i]); |
| 138 | } |
| 139 | |
| 140 | return accumulator; |
| 57 | 141 | } |
| 58 | 142 | |
| 59 | 143 | /** |
| 60 | | * @param {(acc: any, el: any) => any} callback |
| 61 | | * @param {any} initial |
| 62 | | * @return {any} |
| 144 | * Folds (reduces) the list from the right using a callback function. |
| 145 | * @param {Function} callback - Function to apply to accumulator and each item. |
| 146 | * @param {any} initial - Initial value for the accumulator. |
| 147 | * @return {any} The final accumulator value. |
| 148 | * Handled Edge Cases: Empty list |
| 63 | 149 | */ |
| 64 | 150 | foldr(callback, initial) { |
| 65 | | throw new Error('Remove this line and implement the function'); |
| 151 | let accumulator = initial; |
| 152 | |
| 153 | // Edge Case: Empty list |
| 154 | if (this.values.length === 0) { |
| 155 | return accumulator; |
| 156 | } |
| 157 | |
| 158 | // Process from right to left |
| 159 | for (let i = this.values.length - 1; i >= 0; i--) { |
| 160 | accumulator = callback(accumulator, this.values[i]); |
| 161 | } |
| 162 | |
| 163 | return accumulator; |
| 66 | 164 | } |
| 67 | 165 | |
| 68 | 166 | /** |
| 69 | | * @return {List} |
| 167 | * Returns a new list with all items in reverse order. |
| 168 | * @return {List} A new List with items in reverse order. |
| 169 | * Handled Edge Cases: Empty list |
| 70 | 170 | */ |
| 71 | 171 | reverse() { |
| 72 | | throw new Error('Remove this line and implement the function'); |
| 172 | // Edge Case: Empty list |
| 173 | if (this.values.length === 0) { |
| 174 | return new List([]); |
| 175 | } |
| 176 | |
| 177 | const result = []; |
| 178 | for (let i = this.values.length - 1; i >= 0; i--) { |
| 179 | result.push(this.values[i]); |
| 180 | } |
| 181 | return new List(result); |
| 73 | 182 | } |
| 74 | 183 | } |