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README
GPL-2.0

panda简介

panda是脚本语言解释器,它基于javascript,但裁剪了部分语法特性;

panda是轻量级语言,它被设计用来作为嵌入式硬件的解释器;

panda很容易学习。

动手操作

首先,需要一个解释器来执行你编写的脚本,目前有几种方式:

  1. 在Mac或Pc机上运行panda的交互解释器(源代码编译生成)
  2. 通过Mac或Pc连接到安装了cupkee OS的硬件板(这种方式下,你将能够直接操作硬件,更多内容请参考cupkee相关资料)

解释器在显示出一个漂亮(丑陋)的logo后,开始等待用户输入。 你可以键入panda/javascript语句,解释器将进行语法解析、编译为字节码、解释执行,最后将执行结果通过终端返回。

如果你使用panda交互解释器,看到的输出大概就是下面的样子

$ panda/repl
> 

编译panda解释器

获取源代码

cd your_workspace_path
git clone https://github.com/cupkee/panda.git

编译

在编译panda之前,你需要安装gcc编译器以及libreadline库

编译步骤:

  1. 通过终端,进入panda源代码目录
  2. 执行命令 make example
  3. 正常情况下,在panda源代码目录中会出现一个build子目录,这里存放所有编译好的可执行文件
  4. .../panda/build/example/repl 就是我们需要的交互解释器

把panda用到你自己的项目中

正向你所看到的,之前用到的交互解释器只是一个例子程序。

你完全可以将panda用到自己的项目中,作为配置解释器、命令行或其它。

bug反馈

我非常需要实际使用中发现bug的反馈,以便不断对程序进行完善。

欢迎你通过以下两种方式提交bug:

  1. 在github上提交issue(推荐)
  2. 发EMail到bug-report@cupkee.cn

使用简介

panda一个裁剪板的javascript解释器,基础语法与javascript相同,非常易于学习掌握

支持的数据类型

  • undefined类型
  • NaN类型
  • 布尔类型
  • 数值类型
  • 字符串类型
  • 数组类型
  • 对象类型

基本语句

var语句 - 定义变量

  1. 定义变量a, b, c
var a, b, c
  1. 定义变量并赋值
var a = 0, b, c = 'hello'

表达式语句

  1. panda解释器在计算表达式时与标准javascript区别

    不同类型的值进行运算时,不会进行类型转换,直接返回NaN(非数字)

  2. 运算符

  • ++ -- () [] .
  • (单目) - ~ !
    • / %
  • & | ^
  • << >>
  • < > >= <=
  • == !=
  • && ||
  • = += -= * = /= %= &= |= ^= <<= >>=
  • ? :
  • ,
  1. 基本表达式举例
> 1 + 1
2
> (10 + 5) * 3 / 5
9
> 1, 2, 3, 5 + 6
11
> 1 > 2
false
> 'hello' + 'world'
"helloworld"
> 'a1' < 'b2'
true
> 'hello' + 1
NaN
> 1 * 'hello'
NaN
...

if语句

if语句是根据条件选择不同分支处理的语句

if (true) {
    // always execute
} else {
    // never execute
}

if (a > 100) {
    ...
}

while语句

while语句是进行循环处理的语句

while(a++ < 100) {
    ...
}

break语句

break用于跳出循环

continue语句

continue用于跳转到循环条件判断

return语句

return 用于从函数跳出,并可指定返回值

函数

在panda中扩展了javascript定义函数的语法

定义函数

  1. 标准的定义方法
function fn() {
  // statements ...
}

// 匿名函数
var fn = function () {
  // statements ...
}
  1. panda扩展语法

在panda中提供了def关键字,作为function的别名

def fn() {
  // statements ...
}

// 匿名函数
var fn = def () {
}

在panda中定义单语句函数时,可以不带"{}"

def fn() return 0;
var fn = def() return 1;

调用函数

panda支持javascript程序中常用的即时调用

(def(x, y) {
    ...
    return x + y;
})(100, 50);            // return 150

关于new关键字

在panda中不支持new的相关语义,但保留new关键字(不要把"new"作为变量或函数名)。

闭包

panda支持闭包

var fn = (def(n) {
    var c = n;
    return def() return c++;
})(100);

fn() // 100
fn() // 101

复合数据类型

  • panda中的数组和对象与javascript非常相似,但目前只提供了有限的方法。(一个好消息是:panda是开源代码,你可以随意添加需要的方法)

  • Buffer对象来源于nodejs, panda同样也没有实现完整操作接口

  • Date对象目前没有实现, 但已经在计划之中

  • panda对复合类型的支持还在持续完善中, 参考test和example中的代码了解更多(不用担心,代码非常容易理解)

以下是一些使用复合对象的例子

/* array example */
var a = [];         // 定义空数组,赋值到变量a

a.push(1);
a.push('hello');
a.length();         // 2
a[0]                // 1
a[1]                // 'hello'
a[2]                // undefined
a.shift()           // 1
a.length()          // 1
a.pop()             // 'hello'
a.length()          // 0
a[0]                // undefined
a.unshift('hi');
a.push('panda');
a.length()          // 2
a[0]                // 'hi'
a[1]                // 'panda'

a.foreach(def(value, index) {
    ...
});

/* object example */
var o = {};         // 定义空对象,赋值到变量o

o.length();         // 0
o.a                 // undefined
o.a = 1;            // 1
o.a                 // 1
o['a']              // 1
o['a'] = 'hello     // 'hello
o['a']              // 'hello
o.length();         // 1
o.foreach(def(key, value) {
    ...
});

定义原生函数

请参考test和example中的代码,非常简单。

总结和提示

panda目前已经具备了解释器库的基本特性,而且很容易使用,可以用在很多项目中实现很有意思的功能

但以下几点需要注意:

  1. panda还不完善,接口没有达到稳定状态,后续还将保持更新

  2. panda首先被设计用在资源有限的嵌入式处理器,最小4k内存就可以工作,但对于大内存条件没有经过良好测试

  3. panda内建了内存管理和垃圾收集机制,但当前的gc算法对大内存环境没有进行优化,随着内存使用量的增大gc占用的时间会有较大增长

  4. panda不依赖任何操作系统层的支持, 整合到应用中非常简单,但操作系统提供的高级特性(如:多线程/任务,事件处理)需要集成开发人员处理

  5. panda被cupkee(一个开源智能硬件操作系统)用来作为解释器,它的特性和开发进度是被cupkee驱动的

帮助panda成长

  1. 使用并反馈bug或特性需求

  2. 为panda提交代码

  3. 其它你觉得有帮助的任何事

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简介

Panda,嵌入式系统的javascript脚本解释器 展开 收起
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