Tasmota/lib/libesp32/berry/README.md

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<p align="center">
<h1 align="center">
<img src="https://gitee.com/mirrors/Berry/raw/master/berry-logo.png" alt="Berry" width=272 height=128>
</h1>
<p align="center">The Berry Script Language.</p>
</p>
## Introduction
Berry is a ultra-lightweight dynamically typed embedded scripting language. It is designed for lower-performance embedded devices. The Berry interpreter-core's code size is less than 40KiB and can run on less than 4KiB heap (on ARM Cortex M4 CPU, Thumb ISA and ARMCC compiler).
The interpreter of Berry include a one-pass compiler and register-based VM, all the code is written in ANSI C99. In Berry not every type is a class object. Some simple value types, such as int, real, boolean and string are not class object, but list, map and range are class object. This is a consideration about performance.
Register-based VM is the same meaning as above.
Berry has the following advantages:
* Lightweight: A well-optimized interpreter with very little resources. Ideal for use in microprocessors.
* Fast: optimized one-pass bytecode compiler and register-based virtual machine.
* Powerful: supports imperative programming, object-oriented programming, functional programming.
* Flexible: Berry is a dynamic type script, and it's intended for embedding in applications. It can provide good dynamic scalability for the host system.
* Simple: simple and natural syntax, support garbage collection, and easy to use FFI (foreign function interface).
* RAM saving: With compile-time object construction, most of the constant objects are stored in read-only code data segments, so the RAM usage of the interpreter is very low when it starts.
## Documents
LaTeX documents repository: [https://github.com/Skiars/berry_doc](https://github.com/Skiars/berry_doc)
Short Manual: [berry_short_manual.pdf](https://github.com/Skiars/berry_doc/releases/download/latest/berry_short_manual.pdf).
Reference Manual: [berry_rm_en_us.pdf](https://github.com/Skiars/berry_doc/releases/download/latest/berry_rm_en_us.pdf), [berry_rm_zh_cn.pdf](https://github.com/Skiars/berry_doc/releases/download/latest/berry_rm_zh_cn.pdf).
Berry's EBNF grammar definition: [tools/grammar/berry.ebnf](./tools/grammar/berry.ebnf)
## Features
* Base Type
* Nil: `nil`
* Boolean: `true` and `false`
* Numerical: Integer (`int`) and Real (`real`)
* String: Single quotation-mark string and double quotation-mark string
* Class: Instance template, read only
* Instance: Object constructed by class
* Module: Read-write key-value pair table
* List: Ordered container, like `[1, 2, 3]`
* Map: Hash Map container, like `{ 'a': 1, 2: 3, 'map': {} }`
* Range: include a lower and a upper integer value, like `0..5`
* Operator and Expression
* Assign operator: `=`, `+=`, `-=`, `*=`, `/=`, `%=`, `&=`, `|=`, `^=`, `<<=`, `>>=`
* Relational operator: `<`, `<=`, `==`, `!=`, `>`, `>=`
* Logic operator: `&&`, `||`, `!`
* Arithmetic operator: `+`, `-`, `*`, `/`, `%`
* Bitwise operator: `&`, `|`, `~`, `^`, `<<`, `>>`
* Field operator: `.`
* Subscript operator: `[]`
* Connect string operator: `+`
* Conditional operator: `? :`
* Brackets: `()`
* Control Structure
* Conditional statement: `if-else`
* Iteration statement: `while` and `for`
* Jump statement: `break` and `continue`
* Function
* Local variable and block scope
* Return statement
* Nested functions definition
* Closure based on Upvalue
* Anonymous function
* Lambda expression
* Class
* Inheritance (only public single inheritance)
* Method and Operator Overload
* Constructor method
* Destructive method
* Module Management
* Built-in module that takes almost no RAM
* Extension module support: script module, bytecode file module and shared library (like *.so, *.dll) module
* GC (Garbage collection)
* Mark-Sweep GC
* Exceptional Handling
* Throw any exception value using the `raise` statement
* Multiple catch mode
* Bytecode file support
* Export function to bytecode file
* Load the bytecode file and execute
## Build and Run
1. Install the readline library (Windows does not need):
``` bash
sudo apt install libreadline-dev # Ubuntu
brew install readline # MacOS
```
2. Build (The default compiler is GCC):
```
make
```
3. Run:
``` bash
./berry # Bash or PowerShell
berry # Windows CMD
```
4. Install (Only Unix-like):
``` bash
make install
```
## Editor pulgins
[Visual Studio Code](https://code.visualstudio.com/) pulgin are in this directory: [./tools/pulgins/vscode](./tools/pulgins/vscode).
## Examples
After compiling successfully, use the `berry` command with no parameters to enter the REPL environment:
```
Berry 0.0.1 (build in Dec 24 2018, 18:12:49)
[GCC 8.2.0] on Linux (default)
>
```
Now enter this code:
``` lua
print("Hello world!")
```
You will see this output:
```
Hello world!
```
You can copy this code to the REPL:
``` ruby
def fib(x)
if x <= 1
return x
end
return fib(x - 1) + fib(x - 2)
end
fib(10)
```
This example code will output the result `55` and you can save the above code to a plain text file (eg test.be) and run this command:
``` bash
./berry test.be
```
This will also get the correct output.
## License
Berry is free software distributed under the [MIT license](./LICENSE).
The Berry interpreter partly referred to [Lua](http://www.lua.org/)'s design. View Lua's license here: http://www.lua.org/license.html.