pbni-rs

pbni-rs是[PBNI]的Rust绑定,使开发者可以使用Rust语言进行PowerBuilder扩展开发.
[注意] pbni-rs只支持PowerBuilder 10及以上版本.

Feature flags

| Flag | Description | Default | |-------------------|----------------------------------------------------------|------------| | global_function | 全局函数导出 | enabled | | nonvisualobject | 不可视对象导出 | enabled | | visualobject | 可视对象导出 | enabled | | decimal | 日期类型处理,将引入[rust_decimal]库 | enabled | | datetime | 日期类型处理,将引入[chrono]库 | enabled | | vm | 加载虚拟机以及创建[Session]等功能,将引入[libloading]库 | disabled |

什么是PBNI?

[PBNI]是PowerBuilder虚拟机的C++扩展接口(PowerBuilder Native Interface).

![Figure]

通过[PBNI]接口我们可以使用底层语言与PBVM进行集成交互,极大的扩展了PowerBuilder的能力.

其他托管语言类似的技术有[JNI],[C++/CLI]等.

开始使用

添加pbni-rs到Cargo.toml即可使用:

```toml [lib] crate-type = ["cdylib"]

[dependencies] pbni-rs = "0.1.0" ```

数据类型映射

|PowerBuilder|Rust| |---|---| |int|pbint,i16| |uint|pbuint,u16| |long|pblong,i32| |ulong|pbulong,u32| |longlong|pblonglong,i64| |real|pbreal,f32| |double|pbdouble,f64| |decimal|[Decimal] (需要开启decimal特性)| |byte|pbbyte,u8| |boolean|bool| |char|PBChar| |string|&PBStr,PBString,String| |blob|&[u8],Vec<u8>| |date|[NaiveDate] (需要开启datetime特性)| |time|[NaiveTime] (需要开启datetime特性)| |datetime|[NaiveDateTime] (需要开启datetime特性)| |any|Value| |任意对象|Object| |任意数组|Array|

PowerBuilder的所有类型都是Nullable的,Rust里使用Option<T>表示.

字符串

PowerBuilder字符编码是[UTF-16LE],而Rust字符串编码采用的是[UTF-8]编码,这使得字符串操作时可能会有一点的性能损失.如果对性能有较高要求,请使用&PBStr进行交互,避免发生内存拷贝和编码转换.

pbni-rs提供了[pbstr!]宏在编译时生成&'static PBStr:

rust let rstr: &'static str = "hell world!"; let pstr: &'static PBStr = pbstr!("hell world!");

pbni-rs使用[widestring]进行UTF-16编码转换.

内存安全

pbni-rs的Safe代码提供100%类型和内存安全保证,对于无法提供100%的内存安全保证的接口都使用了unsafe标记.最常见的就是获取引用,比如&PBStr.

rust impl<'obj> Object<'obj> { pub unsafe fn get_var_str(&self, fid: impl VarId) -> Option<&'obj PBStr> { ... } pub fn get_var_string(&self, fid: impl VarId) -> Option<PBString> { ... } pub fn set_var_str(&mut self, fid: impl VarId, value: impl AsPBStr) -> Result<()> { ... } }

可以看到Object的get_var_str是unsafe方法,而get_var_string则是Safe的,这是因为像set_var_str这样的方法可能会修改get_var_str返回引用的内存,导致垂悬引用([Dangling Reference]).
pbni-rs无法避免这种情况,因为对象的内部状态不完全由Rust维护,有很多途径会导致内存被修改,所以pbni-rs中所有返回引用的方法都将是[Unsafe]的,需要开发者自己保证对其正确使用.

线程安全

Session及其所有分配的资源都不能跨线程访问(包括Object/Array),因此它们都不是Send和Sync的,跨线程访问建议结合消息队列实现.

代码生成

pbni-rs可以非常方便将Rust对象或函数与PowerBuilder建立映射,全部由pbni-rs生成代码,省去手写繁琐的样板代码的同时保证了类型安全.

映射PowerBuilder全局函数

PowerBuilder

```vbscript global type gfbitor from function_object native "pbrs.dll" end type

forward prototypes global function long gfbitor (readonly long a,readonly long b) end prototypes ```

```cpp

include

PBXRESULT bitor(PBCallInfo *ci) { pblong a = ci->pArgs->GetAt(0)->GetLong(); pblong b = ci->pArgs->GetAt(1)->GetLong(); return ci->returnValue->SetLong(a|b); } PBXRESULT PBXCALL PBXInvokeGlobalFunction( IPBSession *pbsession, LPCWSTR functionName, PBCallInfo *ci) { if(::wcscmp(functionName,L"gfbitor") == 0) return bitor(ci); return PBXENOREGISTERFUNCTION; } ```

Rust(pbni-rs)

```rust use pbni::*;

[globalfunction(name="gfbit_or")]

fn bit_or(a: pblong, b: pblong) -> pblong { a | b } ```

映射PowerBuilder对象

PowerBuilder

```vbscript forward global type n_pbni from nonvisualobject end type end forward

global type npbni from nonvisualobject native "pbrs.dll" public function string ofhello (string world) end type global npbni npbni

on n_pbni.create call super::create TriggerEvent( this, "constructor" ) end on

on n_pbni.destroy TriggerEvent( this, "destructor" ) call super::destroy end on ```

```cpp

include

class CppObject: public IPBXNonVisualObject { IPBSession *session; pbobject ctx;

PBXRESULT handle_hello(PBCallInfo *ci)
{
    LPCWSTR lpcsWorld = this->session->GetString(ci->pArgs->GetAt(0)->GetString());
    std::wostringstream ss;
    ss << L"hello " << lpcsWorld << L"!";
    return ci->returnValue->SetString(ss.str().c_str());
}

public: CppObject(IPB_Session *pbsession,pbobject pbobj) :session(pbsession), ctx(pbobj) {} virtual ~CppObject() override {};

virtual void Destroy() override { delete this; }

virtual PBXRESULT Invoke(
    IPB_Session *session,
    pbobject obj,
    pbmethodID mid,
    PBCallInfo *ci) override

{ if(mid == 0) return this->handlehello(ci); return PBXENOREGISTER_FUNCTION; } };

PBXRESULT PBXCALL PBXCreateNonVisualObject( IPBSession pbsession, pbobject pbobj, LPCWSTR className, IPBX_NonVisualObject *obj) { if(::wcscmp(className,L"npbni") == 0) { *obj = new CppObject(pbsession,pbobj); return PBXOK; } return PBXENOSUCHCLASS; } ```

Rust(pbni-rs)

```rust use pbni::*;

struct RustObject { session: Session, ctx: ContextObject }

[nonvisualobject(name = "n_pbni")]

impl RustObject { #[constructor] fn new(session: Session, ctx: ContextObject) -> RustObject { RustObject { session, ctx } } #[method(name="of_Hello")] fn hello(&self, world: String) -> String { format!("hello {}!",world) } } ```

参数提取

pbni-rs代码生成宏会自动提取PB参数为Rust映射的[数据类型],参数的提取顺序与PB端定义的顺序保持一致.其中有几个特殊的参数: [Session]/[CallInfoRef]/[ArgumentsRef],这几个参数对位置没有要求并且数量任意.

```rust use pbni::*;

[globalfunction(name="gfbit_or")]

fn bit_or(session: Session,a: pblong, b: pblong) -> pblong { a | b }

//等同于

[globalfunction(name="gfbit_or")]

fn bitor(session: Session,args: ArgumentsRef,a: pblong) -> pblong { a | args.get(1).getlong().unwrap() } ```

注意 Rust端参数列表须与PB端定义的类型数量以及顺序一致,任何不匹配的情况都会在运行时触发异常.
当参数列表通过CallInfoRef/ArgumentsRef接收后,将不再匹配参数数量,因为这两个参数已经隐式表示接收了所有的参数.CallInfoRef/ArgumentsRef一般用于处理引用传递参数以及变长参数列表.

可选参数列表匹配

以下示例为重载可选参数列表的匹配映射

PowerBuilder

```vbscript global type gftest from functionobject native "pbrs.dll" end type

forward prototypes global function long gftest (readonly long a,readonly long b) global function long gftest (readonly long a,readonly long b,readonly long c) global function long gf_test (readonly long a,readonly long b,readonly long c,readonly long d) end prototypes ```

Rust(pbni-rs)

```rust use pbni::*;

[globalfunction(name="gftest")]

fn test(a: pblong, b: pblong, c: Option, d: Option) -> pblong { a | b } ```