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// Copyright 2017 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package fn
import (
"reflect"
)
func Wrap(f interface{}) *fn {
t := reflect.TypeOf(f)
if t.Kind() != reflect.Func {
panic("fn only support wrap a function to http.Handler")
}
numOut := t.NumOut()
// Supported signatures
// func(...) (Response, error)
if numOut != 2 {
panic("unsupported function type, function return values should contain response data & error")
}
var (
adapter adapter
numIn = t.NumIn()
inContext = false
)
if numIn > 0 {
for i := 0; i < numIn; i++ {
// Legal: func(ctx context.Context, ...) ...
if t.In(i) == contextType {
// Illegal: func(..., ctx context.Context, ...) ...
if i != 0 {
panic("the `context.Context` must be the first parameter if the signature contains `context.Context`")
}
// Illegal: func(..., ctx context.Context, ..., ctx2 context.Context) ...
if inContext {
panic("the function can receive two `context.Context`")
}
inContext = true
}
}
}
if numIn == 0 {
// func() (Response, error)
adapter = &simplePlainAdapter{
inContext: false,
method: reflect.ValueOf(f),
cacheArgs: []reflect.Value{},
}
} else if numIn == 1 && inContext {
// func(ctx context.Context) (Response, error)
adapter = &simplePlainAdapter{
inContext: true,
method: reflect.ValueOf(f),
cacheArgs: make([]reflect.Value, 1),
}
} else if numIn == 1 && !isBuiltinType(t.In(0)) && t.In(0).Kind() == reflect.Ptr {
// func(request *Customized) (Response, error)
adapter = &simpleUnaryAdapter{
argType: t.In(0),
method: reflect.ValueOf(f),
cacheArgs: make([]reflect.Value, 1),
}
} else {
// Complicated signatures
//
// e.g:
// type LoginResponse {...}
// type LoginRequest {...}
//
// func (header http.Header) (*LoginResponse, error) {}
// func (form fn.Form) (*LoginResponse, error) {}
// func (header http.Header, form fn.Form, body io.ReadCloser) (*LoginResponse, error) {}
// func (header http.Header, r *LoginRequest, url *url.URL) (*LoginResponse, error) { }
adapter = makeGenericAdapter(reflect.ValueOf(f), inContext)
}
return &fn{adapter: adapter}
}
func SetErrorEncoder(c ErrorEncoder) {
if c == nil {
panic("nil pointer to error encoder")
}
errorEncoder = c
}
func SetResponseEncoder(c ResponseEncoder) {
if c == nil {
panic("nil pointer to error encoder")
}
responseEncoder = c
}
func SetMultipartFormMaxMemory(m int64) {
maxMemory = m
}
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