datastructures

AssemblyScript WASM - Datastructures

This example package demonstrates compiling a AssemblyScript program, datastructures.ts which demonstrates working with the AssemblyScript Map and Set data structures.

Installing Dependencies

from the add directory project root:

npm install

Compiling AssemblyScript to WASM

To compile the datastructures.ts code to a WASM binary:

npm run build

A datastructures.wasm file will be produced in the build directory

Testing

Test the module outside of the context of the blockchain:

npm test

This will run NodeJS based tests in the test directory. For example in datastructures.unit.spec.js test instantiation of the compiled WASM module, and assertions to verify its API and behavior:

describe('Map', function () {
        it('Set', function () {
            //create a pointer to the string param "hello" we will pass in as the value
            let paramPointer0 = module.__retain(module.__allocString("hello"));

            //set the key 0 => "hello"
            module.mapSet(0, paramPointer0);
            module.__release(paramPointer0); //release the memory for the pointer
            
            //get the value from memory
            const pointer = module.mapGet(0);
            const string = module.__getString(pointer);
            module.__release(pointer);

            assert.strictEqual(string, 'hello'); // => true!
        });
    
    ...
    });

API

arrayPush(string(i32) x) - void

Add the string at pointer x to the end of the internal Array

arrayPop() - string(i32)

Remove the last element from the internal array and return the pointer to the string element

arrayShift() - string(i32)

Remove the first element from the internal array and return the pointer to the string element

arrayGet(string(i8) x) - void

Get the pointer to the string at index x in the internal Array

arrayLength() - i32

Return the length of the internal Array

setAdd(string(i32) x) - void

Add the string at pointer x to the internal Set

setHas(string(i32) x) - i32

Check if the string at pointer x is contained in the internal Set. Return the integer representation of the boolean result (0/1)

setSize() - i32

Return the number of elements in the internal Set (cardinality)

mapSet(i32 k, string(i32) v) - i32

Set the integer key k in the internal Map<i32, string> to string value at pointer v

mapGet(i32 k) - string(i32)

Return the pointer to the string value in memory mapped to int k

mapSize() - i32

Return the number of keys in the internal Map<i32, string>