README
¶
proxyz
ProxyZ is a proxy generator for Go.
It analyzes the method sets of Go types from the sources and then generates code of wrapper structures for the types, which work as proxies. You might intercept method calls via the the proxies in order to check/modify the arguments and results of the method calls, even bypass the method calls.
Features
- Supports method call interception
- Supports embedded structures/interfaces analysis
Installation
go get github.com/roy2220/proxyz/...
go install github.com/roy2220/proxyz/cmd/proxyz
Usage
proxyz [--format] [--write FILE] IPKG ITYPE OPKG OTYPE
Positional arguments:
IPKG input package
ITYPE input type
OPKG output package
OTYPE output type
Options:
--format, -f format output [default: true]
--write FILE, -w FILE
write output to file inside output package directory
--help, -h display this help and exit
Quick Start
1. Create new file calc.go
package main
import "fmt"
type calc struct {
}
func (calc) Sum(x, y int) string {
s := fmt.Sprintf("%d + %d = %d", x, y, x+y)
return s
}
func main() {
var c calc
s := c.Sum(1, 2)
fmt.Println(s)
// Output: 1 + 2 = 3
}
2. Generate proxy
"$(go env GOPATH)/bin/proxyz" . calc . calcProxy -w calcproxy.go
# output written to file "calcproxy.go"
See Usage for explanation
3. Update file calc.go
package main
import (
"fmt"
"strings"
"github.com/roy2220/proxyz"
)
type calc struct {
}
func (calc) Sum(x, y int) string {
s := fmt.Sprintf("%d + %d = %d", x, y, x+y)
return s
}
func main() {
var c calc
// new a proxy.
cp := newCalcProxy(&c) // function `newCalcProxy` is generated by proxyz.
// add a method call interceptor.
cp.XxxInterceptMethodCall(
// method index, indicating the method `Sum` here.
calcProxySum, // constant `calcProxySum` is generated by proxyz.
// method call intercepting function.
func(mc proxyz.MethodCall) {
// modify the second argument `y`, whose index is 1.
y := mc.GetArg(1).(int)
y += 100
mc.SetArg(1, y)
// forward the method call to the next interceptor, if any,
// or forward to the underlying object `calc`.
// NOTE: without this call, the method `Sum` will NOT be
// actually called, and no result provided.
mc.Forward()
// modify the first (only) result, whose index is 0.
s := mc.GetResult(0).(string)
s = strings.ReplaceAll(s, "=", "!=")
mc.SetResult(0, s)
},
)
// call Sum() from the proxy.
s := cp.Sum(1, 2)
fmt.Println(s)
// Output: 1 + 102 != 103
}
4. Run the code
go run calc.go calcproxy.go
# 1 + 102 != 103
See examples/calc for the complete code
Documentation
¶
Overview ¶
Package proxyz defines common interfaces and utility for generated code.
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type MethodCall ¶
type MethodCall interface {
// Forward forwards the method call to the next interceptor, if any,
// or forwards to the underlying object to call the real method.
//
// It should be manually called in the body of every intercepting
// function, otherwise the method will NOT be actually called.
Forward()
// GetArg returns the argument of the method call at the given index.
GetArg(argIndex int) (arg interface{})
// SetArg sets the argument of the method call at the given index.
SetArg(argIndex int, arg interface{})
// GetResult returns the result of the method call at the given index.
GetResult(resultIndex int) (result interface{})
// SetResult sets the result of the method call at the given index.
SetResult(resultIndex int, result interface{})
// MethodName returns the name of the method called.
MethodName() string
// MethodIndex returns the index of the method called.
MethodIndex() int
// NumberOfArgs returns the number of the arguments of the method call.
NumberOfArgs() int
// NumberOfResults returns the number of the results of the method call.
NumberOfResults() int
}
MethodCall represents a call to a method.
type MethodCallInterceptor ¶
type MethodCallInterceptor func(methodCall MethodCall)
MethodCallInterceptor is the type of function intercepting calls to methods.
type Proxy ¶
type Proxy interface {
// XxxInterceptMethodCall adds an interceptor to intercept the calls
// to the method at the given index.
XxxInterceptMethodCall(methodIndex int, methodCallInterceptor MethodCallInterceptor)
// XxxGetMethodName returns the name of the method at the given index.
XxxGetMethodName(methodIndex int) string
// XxxNumberOfMethods returns the number of the methods of the proxy
// generated, excluding the methods whose names start with 'Xxx'.
XxxNumberOfMethods() int
// XxxUnderlyingType returns the representation of the underlying type of
// the proxy generated.
XxxUnderlyingType() string
}
Proxy represents a proxy generated.
type XxxProxyBase ¶
type XxxProxyBase struct {
// contains filtered or unexported fields
}
XxxProxyBase represents the base of proxies generated.
func (*XxxProxyBase) XxxGetMethodCallInterceptors ¶
func (pb *XxxProxyBase) XxxGetMethodCallInterceptors(methodIndex int) []MethodCallInterceptor
XxxGetMethodCallInterceptors returns the interceptors applied to the calls to the method at the given index. It serves for generated code.
func (*XxxProxyBase) XxxInterceptMethodCall ¶
func (pb *XxxProxyBase) XxxInterceptMethodCall(methodIndex int, methodCallInterceptor MethodCallInterceptor)
XxxInterceptMethodCall implements Proxy.XxxInterceptMethodCall.
Source Files
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