Map

To address the inconvenience of working with compound tags in vanilla Minecraft NBT, MCFPP introduces a new data structure: map. A map is a key-value data structure where the keys must be strings, and the values must all be of the same type.

Basic Usage

Use map<type T> to declare a map. Like with dict, you can access key-value pairs in a map using [].

var m as map<int> = {
    "a": 1,
    "b": 2,
    "c": 3
};

print(m["a"]); # Outputs 1

m["d"] = 4; # Adds a new key-value pair

map Operations

The MCFPP standard library provides a series of functions to manipulate map.

Function Name	Parameters	Return Value	Description
clear	void	void	Clears the map
containsKey	string key	bool	Checks if the map contains the specified key
containsValue	T value	bool	Checks if the map contains the specified value
isEmpty	void	bool	Checks if the map is empty
remove	string key	void	Removes the key-value pair for the specified key
merge	map<T> map	void	Merges two maps
size	void	int	Returns the size of the map

As well as some properties:

Property Name	Type	Description
keys	string	Gets all the keys in the map

map Traversal Future Feature

You can use the foreach loop to easily traverse all key-value pairs in a map.

var m as map<int> = {
    "a": 1,
    "b": 2,
    "c": 3
};

foreach(k, v in m){
    print(k + ": " + v);
}

foreach(k in m.getKeys()){
    print(k + ": " + m[k]);
}

foreach(v in m.getValues()){
    print(v);
}

Tip

Compared to dict, which is composed solely of compound tags, map has a more complex structure. Typically, a map consists of three parts: a list of keys, a list of values, and a compound tag representing the key-value pairs. This structure means that writing data to a map has a higher overhead than writing to a dict. However, this structure also grants map more functionality.

For instance, consider the following code:

var m as map<string> = {};

m["qwq"] = "pwp";
m["owo"] = "uwu";
m["nya"] = "meow";

When stored, the structure of the map would look like this:

namespace.stack_frame:[
    {
        m:{
            keys:["qwq","owo","nya"],        // Key list
            keyValueSet:{
                "qwq":"pwp","owo":"uwu","nya":"meow"    // Key-value pairs, similar to a dict
            }    
        }
    }
]