本文通过一个Go语言接口示例，展示了如何将Go的接口特性映射到C语言中实现。具体包括定义接口、实现接口的结构体以及转换过程。
我写了一个 go interface 相关的代码转换为 C 代码的样例。也许有助于大家理解 go 的 interface。不过请注意一点，这里没有完整解析 go 语言 interface 的所有细节。
Go 代码：
package main
import "fmt"
// ------------------------------------------------------------ -
type IReadWriter interface {
Read(buf *byte, cb int) int
Write(buf *byte, cb int) int
}
// ------------------------------------------------------------ -
type A struct {
a int
}
func NewA(params int) *A {
fmt.Println("NewA:", params);
return &A{params}
}
func (this *A) Read(buf *byte, cb int) int {
fmt.Println("A_Read:", this.a)
return cb
}
func (this *A) Write(buf *byte, cb int) int {
fmt.Println("A_Write:", this.a)
return cb
}
// ------------------------------------------------------------ -
type B struct {
A
}
func NewB(params int) *B {
fmt.Println("NewB:", params);
return &B{A{params}}
}
func (this *B) Write(buf *byte, cb int) int {
fmt.Println("B_Write:", this.a)
return cb
}
func (this *B) Foo() {
fmt.Println("B_Foo:", this.a)
}
// ------------------------------------------------------------ -
func main() {
var p IReadWriter = NewB(8)
p.Read(nil, 10)
p.Write(nil, 10)
}
// ------------------------------------------------------------ -
对应的 C 代码：
#include <stdio.h>
#include <stdlib.h>
// ------------------------------------------------------------ -
typedef struct _TypeInfo {
// 用于运行时取得类型信息, 比如反射机制
} TypeInfo;
typedef struct _InterfaceInfo {
// 用于运行时取得interface信息
} InterfaceInfo;
// ------------------------------------------------------------ -
typedef struct _IReadWriterTbl {
InterfaceInfo* inter;
TypeInfo* type;
int (*Read)(void* this, char* buf, int cb);
int (*Write)(void* this, char* buf, int cb);
} IReadWriterTbl;
typedef struct _IReadWriter {
IReadWriterTbl* tab;
void* data;
} IReadWriter;
InterfaceInfo g_InterfaceInfo_IReadWriter = {
// ...
};
// ------------------------------------------------------------ -
typedef struct _A {
int a;
} A;
int A_Read(A* this, char* buf, int cb) {
printf("A_Read: %d\n", this->a);
return cb;
}
int A_Write(A* this, char* buf, int cb) {
printf("A_Write: %d\n", this->a);
return cb;
}
TypeInfo g_TypeInfo_A = {
// ...
};
A* NewA(int params) {
printf("NewA: %d\n", params);
A* this = (A*)malloc(sizeof(A));
this->a = params;
return this;
}
// ------------------------------------------------------------ -
typedef struct _B {
A base;
} B;
int B_Write(B* this, char* buf, int cb) {
printf("B_Write: %d\n", this->base.a);
return cb;
}
void B_Foo(B* this) {
printf("B_Foo: %d\n", this->base.a);
}
TypeInfo g_TypeInfo_B = {
// ...
};
B* NewB(int params) {
printf("NewB: %d\n", params);
B* this = (B*)malloc(sizeof(B));
this->base.a = params;
return this;
}
// ------------------------------------------------------------ -
IReadWriterTbl g_Itbl_IReadWriter_B = {
&g_InterfaceInfo_IReadWriter,
&g_TypeInfo_B,
(int (*)(void* this, char* buf, int cb))A_Read,
(int (*)(void* this, char* buf, int cb))B_Write
};
int main() {
B* unnamed = NewB(8);
IReadWriter p = {
&g_Itbl_IReadWriter_B,
unnamed
};
p.tab->Read(p.data, NULL, 10);
p.tab->Write(p.data, NULL, 10);
return 0;
}
// ------------------------------------------------------------ -
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