Package & Module

Source code module

You can use import declaration within your code to include other source. The interpreter will interpret those imported sources first.

Bytecode module

You can use compile() to make a single file bytecode module. The compiler with automatically compile every other source that the code imported.

Resource context

If a source contains import statement, the parser will try to fetch another source content by the import path through a helper class HTResourceContext. The default HTResourceContext provided by the Interpreter is HTOverlayContext, it will not handle physical files and you need to manually add String content into the context before you run the script for it to import from.

Resource type

Hetu script file have 3 way to interpret, controlled by the ResourceType type parameter in the eval method of the Interpreter class or the extension of the source file.

When ResourceType is not provided in interpreter's 'eval' method, interpreter will evaluate the string provided as ResourceType.hetuLiteralCode. Other than the code use global as its namespace. It is the same to ResourceType.hetuScript.
For ResourceType.hetuScript, the source file is organized like a Javascript, Python and Lua file. It has its own namespace. It may contain any expression and control statement that is allowed in a function body (including nested function and class declaration). And every expression is immediately evaluated.
For ResourceType.hetuModule, the source file is organized like a C++, Java or Dart app. It only contains import statement and declarations(variable, function and class). The top level variables are lazily initialized (initialize when first used).

When using evalFile method on the interpreter, the source type is inferred from the extension of the file name: '*.hts' is ResourceType.hetuScript, and '*.ht' is ResourceType.hetuModule.

Import a pre-compiled binary module

You can pre-compiled a hetu script package into a binary module for better performance. If you have a such module. You can import it by using special prefix in import path. Note that for anlysis purpose, you have to provide a alias name for this imported module.

import 'module:calculate' as calculate;

final result = calculate.calculate()

However, to do so, you have to load the bytecode before you can import it in your script. This is a example to pre-load a pre-compiled binary file:

import 'dart:io';

import 'package:hetu_script/hetu_script.dart';
import 'package:hetu_script_dev_tools/hetu_script_dev_tools.dart';

void main() {
  final sourceContext = HTFileSystemResourceContext(root: 'example/script/');
  final hetu = Hetu(sourceContext: sourceContext);
  hetu.init();
  final binaryFile = File('example/script/module.out');
  final bytes = binaryFile.readAsBytesSync();
  hetu.loadBytecode(bytes: bytes, module: 'calculate');
  hetu.evalFile('import_binary_module.hts');
}

Import a JSON file

Sometimes we need to import a non-hetu source in your code. For example, if you imported a JSON file, you will get a HTStruct object from it. Because the syntax of a JSON is fully compatible with Hetu's struct object.

The two implementation of HTResourceContext (HTFileSystemResourceContext & HTAssetResourceContext) will automatically include json and json5 file extensions, and you can import them as normal source files.

Example code (dart part):

import 'package:hetu_script/hetu_script.dart';
import 'package:hetu_script_dev_tools/hetu_script_dev_tools.dart';

void main() {
  final sourceContext = HTFileSystemResourceContext(root: 'example/script');
  final hetu = Hetu(sourceContext: sourceContext);
  hetu.init();

  hetu.eval('''
    import 'values.json' as json
    print(json.name) // use json value like a struct
  ''');
}

Note that you have to provide a alias name for this imported json file.

# Package & Module

# Source code module

# Bytecode module

# Resource context

# Resource type

# Import a pre-compiled binary module