Dictionaries

Table of contents

1. Dictionaries
   1. Indexing
   2. dict.get(String, value: default -> Optional) -> Dict
   3. dict.keys() -> List
   4. dict.toString() -> String
   5. dict.toBool() -> Boolean
   6. dict.len() -> Number
   7. dict.exists(String) -> Boolean
   8. dict.remove(String)
   9. Copying dictionaries
   10. dict.forEach(Func)
   11. dict.merge(Dict)

Dictionaries

Dictionaries are a key:value pair data type. Dictu requires that the dictionary key be an immutable type (nil, boolean, number, string), however the value can be any type.

var myDict = {"key": 1, "key1": true};

Indexing

Accessing dictionary items is the same syntax as lists, except instead of an index, it expects an immutable type (nil, boolean, number, string) for it’s key. If you try to access a key that does not exist, a runtime error will be raised. If you expect a key may not exist .get() can be used to return a default value.

var myDict = {"key": 1, "key1": true};
var someItem = myDict["key"]; // 1
var nilValue = myDict["unknown key"]; // nil

Updating a value within a dictionary uses the same syntax, except you supply a value via assignment.

var myDict = {"key": 1, "key1": true};
var myDict["key"] = false; // {"key": false, "key1": true}

Adding a value to a dictionary is the same as updating a value, however if the key does not exist it is created.

var myDict = {"key": 1, "key1": true};
var myDict["key2"] = nil; // {"key": false, "key1": true, "key3": nil}

dict.get(String, value: default -> Optional) -> Dict

Returns the dictionary value at the given key, or returns the default value if the key does not exist in the dictionary. If the key does not exist and no default is provided nil is returned.

var myDict = {};

myDict.get("unknown key", "No key!"); // No key!
myDict.get("unknown key", 10); // 10
myDict.get("unknown key"); // nil

dict.keys() -> List

Returns a list of all of the dictionary keys.

var myDict = {1: 2, "test": 3};

myDict.keys(); // [1, "test"]

dict.toString() -> String

Converts a dictionary to a string.

{"1": 1, 1: "1"}.toString(); // '{"1": 1, 1: "1"}'
{"1": {1: "1", "1": 1}, 1: "1"}.toString(); // '{"1": {"1": 1, 1: "1"}, 1: "1"}'

dict.toBool() -> Boolean

Converts a dictionary to a boolean. A dictionary is a “truthy” value when it has a length greater than 0.

var x = {};

x.toBool(); // false
x["test"] = 1;
x.toBool(); // true

dict.len() -> Number

Returns the length of the given dictionary.

{1: "one", 2: "two", 3: "three"}.len(); // 3

dict.exists(String) -> Boolean

To check if a key exists within a dictionary use .exists()

var myDict = {"key": 1, "key1": true};
var keyExists = myDict.exists("key"); // true
var keyDoesNotExist = myDict.exists("unknown key"); // false

dict.remove(String)

To remove a key from a dictionary use .remove().

Note: If you try to remove a key that does not exist a runtime error is raised, use together with .exists().

var myDict = {"key": 1, "key1": true};
myDict.remove("key");
myDict; // {'key1': true}
myDict.remove("unknown key"); // [line 1] in script: Key 'unknown key' passed to remove() does not exist

Copying dictionaries

This is the exact same scenario as lists, so refer to copying Lists for information as to what is happening.

var myDict = {"key": {"test": 10}};
var myDict1 = myDict.copy(); // Shallow copy
var myDict2 = myDict.deepCopy(); // Deep copy

dict.forEach(Func)

To run a function on every element in a dictionary we use .forEach. The callback function passed to .forEach expects two parameters which will be the key-value pair of the dictionary.

const myDict = {"key": 1, "key1": 2};

myDict.forEach(def (key, value) => {
    print("Key: {} Value: {}".format(key, value));
});

dict.merge(Dict)

To merge two dicts together we use .merge. This operation will take a shallow copy of the dict the .merge method was called on and add any items from the dictionary passed into the method. If there are keys that exist in both dictionaries the value from the passed in dictionary is the one that will be used.

const dictOne = {"key": 1, "key1": 2, "key2": 3};
const dictTwo = {"key3": 4,"key1":0};

const mergedDict = dictOne.merge(dictTwo);

mergedDict; //{"key2": 3, "key": 1, "key3": 4, "key1": 0}