rotrics-scratch-vm

scratch-vm

#### Scratch VM is a library for representing, running, and maintaining the state of computer programs written using Scratch Blocks.


Installation

``bash
npm install scratch-vm
`

Setup

`js
var VirtualMachine = require('scratch-vm');
var vm = new VirtualMachine();

// Block events
workspace.addChangeListener(function(e) {
// Handle "tapping" a block
if (e instanceof Blockly.Events.Ui && e.element === 'click') {
var stackBlock = workspace.getBlockById(e.blockId).getRootBlock().id;
vm.runtime.toggleStack(stackBlock);
// Otherwise, pass along to the block listener
} else {
vm.blockListener(e);
}
});

// Run threads
vm.runtime.start();
`

Standalone Build

`bash
make build
`

`html


`

Abstract Syntax Tree

#### Overview
The Virtual Machine constructs and maintains the state of an Abstract Syntax Tree (AST) by listening to events emitted by the scratch-blocks workspace via the blockListener. At any time, the current state of the AST can be viewed by inspecting the vm.runtime.blocks object.

#### Anatomy of a Block
`json
{
"id": "^1r~63Gdl7;Dh?I*OP3_",
"opcode": "wedo_motorclockwise",
"next": null,
"fields": {
"DURATION": {
"name": "DURATION",
"value": null,
"blocks": {
"1?P=eV(OiDY3vMk!24Ip": {
"id": "1?P=eV(OiDY3vMk!24Ip",
"opcode": "math_number",
"next": null,
"fields": {
"NUM": {
"name": "NUM",
"value": "10",
"blocks": null
}
}
}
}
},
"SUBSTACK": {
"name": "SUBSTACK",
"value": "@1ln(HsUO4!]2%BrE|",
"blocks": null
}
}
}
`

Testing

`bash
make test
`

`bash
make coverage
``

Donation

We provide Scratch free of charge, and want to keep it that way! Please consider making a donation to support our continued engineering, community, and resource development efforts. Donations of any size are appreciated. Thank you!