// boundMethodWrapper returns a synthetic wrapper function that
// delegates to a concrete or interface method.
// The wrapper has one free variable, the method's receiver.
// Use MakeClosure with such a wrapper to construct a bound-method
// closure. e.g.:
//
// type T int or: type T interface { meth() }
// func (t T) meth()
// var t T
// f := t.meth
// f() // calls t.meth()
//
// f is a closure of a synthetic wrapper defined as if by:
//
// f := func() { return t.meth() }
//
// EXCLUSIVE_LOCKS_ACQUIRED(meth.Prog.methodsMu)
//
func boundMethodWrapper(prog *Program, obj *types.Func) *Function {
prog.methodsMu.Lock()
defer prog.methodsMu.Unlock()
fn, ok := prog.boundMethodWrappers[obj]
if !ok {
description := fmt.Sprintf("bound method wrapper for %s", obj)
if prog.mode&LogSource != 0 {
defer logStack("%s", description)()
}
fn = &Function{
name: "bound$" + obj.FullName(),
Signature: changeRecv(obj.Type().(*types.Signature), nil), // drop receiver
Synthetic: description,
Prog: prog,
Pkg: prog.packages[obj.Pkg()],
pos: obj.Pos(),
}
cap := &Capture{name: "recv", typ: recvType(obj), parent: fn}
fn.FreeVars = []*Capture{cap}
fn.startBody()
createParams(fn)
var c Call
if _, ok := recvType(obj).Underlying().(*types.Interface); !ok { // concrete
c.Call.Value = prog.declaredFunc(obj)
c.Call.Args = []Value{cap}
} else {
c.Call.Value = cap
c.Call.Method = obj
}
for _, arg := range fn.Params {
c.Call.Args = append(c.Call.Args, arg)
}
emitTailCall(fn, &c)
fn.finishBody()
prog.boundMethodWrappers[obj] = fn
}
return fn
}