method5.go

// run

// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

// Concrete types implementing M method.
// Smaller than a word, word-sized, larger than a word.
// Value and pointer receivers.

type Tinter interface {
	M(int, byte) (byte, int)
}

type Tsmallv byte

func (v Tsmallv) M(x int, b byte) (byte, int) { return b, x+int(v) }

type Tsmallp byte

func (p *Tsmallp) M(x int, b byte) (byte, int) { return b, x+int(*p) }

type Twordv uintptr

func (v Twordv) M(x int, b byte) (byte, int) { return b, x+int(v) }

type Twordp uintptr

func (p *Twordp) M(x int, b byte) (byte, int) { return b, x+int(*p) }

type Tbigv [2]uintptr

func (v Tbigv) M(x int, b byte) (byte, int) { return b, x+int(v[0])+int(v[1]) }

type Tbigp [2]uintptr

func (p *Tbigp) M(x int, b byte) (byte, int) { return b, x+int(p[0])+int(p[1]) }

// Again, with an unexported method.

type tsmallv byte

func (v tsmallv) m(x int, b byte) (byte, int) { return b, x+int(v) }

type tsmallp byte

func (p *tsmallp) m(x int, b byte) (byte, int) { return b, x+int(*p) }

type twordv uintptr

func (v twordv) m(x int, b byte) (byte, int) { return b, x+int(v) }

type twordp uintptr

func (p *twordp) m(x int, b byte) (byte, int) { return b, x+int(*p) }

type tbigv [2]uintptr

func (v tbigv) m(x int, b byte) (byte, int) { return b, x+int(v[0])+int(v[1]) }

type tbigp [2]uintptr

func (p *tbigp) m(x int, b byte) (byte, int) { return b, x+int(p[0])+int(p[1]) }

type tinter interface {
	m(int, byte) (byte, int)
}

// Embedding via pointer.

type T1 struct {
	T2
}

type T2 struct {
	*T3
}

type T3 struct {
	*T4
}

type T4 struct {
}

func (t4 T4) M(x int, b byte) (byte, int) { return b, x+40 }

var failed = false

func CheckI(name string, i Tinter, inc int) {
	b, x := i.M(1000, 99)
	if b != 99 || x != 1000+inc {
		failed = true
		print(name, ".M(1000, 99) = ", b, ", ", x, " want 99, ", 1000+inc, "\n")
	}
	
	CheckF("(i="+name+")", i.M, inc)
}

func CheckF(name string, f func(int, byte) (byte, int), inc int) {
	b, x := f(1000, 99)
	if b != 99 || x != 1000+inc {
		failed = true
		print(name, "(1000, 99) = ", b, ", ", x, " want 99, ", 1000+inc, "\n")
	}
}

func checkI(name string, i tinter, inc int) {
	b, x := i.m(1000, 99)
	if b != 99 || x != 1000+inc {
		failed = true
		print(name, ".m(1000, 99) = ", b, ", ", x, " want 99, ", 1000+inc, "\n")
	}
	
	checkF("(i="+name+")", i.m, inc)
}

func checkF(name string, f func(int, byte) (byte, int), inc int) {
	b, x := f(1000, 99)
	if b != 99 || x != 1000+inc {
		failed = true
		print(name, "(1000, 99) = ", b, ", ", x, " want 99, ", 1000+inc, "\n")
	}
}

func shouldPanic(f func()) {
	defer func() {
		if recover() == nil {
			panic("not panicking")
		}
	}()
	f()
}

func shouldNotPanic(f func()) {
	f()
}

func main() {
	sv := Tsmallv(1)
	CheckI("sv", sv, 1)
	CheckF("sv.M", sv.M, 1)
	CheckF("(&sv).M", (&sv).M, 1)
	psv := &sv
	CheckI("psv", psv, 1)
	CheckF("psv.M", psv.M, 1)
	CheckF("(*psv).M", (*psv).M, 1)

	sp := Tsmallp(2)
	CheckI("&sp", &sp, 2)
	CheckF("sp.M", sp.M, 2)
	CheckF("(&sp).M", (&sp).M, 2)
	psp := &sp
	CheckI("psp", psp, 2)
	CheckF("psp.M", psp.M, 2)
	CheckF("(*psp).M", (*psp).M, 2)

	wv := Twordv(3)
	CheckI("wv", wv, 3)
	CheckF("wv.M", wv.M, 3)
	CheckF("(&wv).M", (&wv).M, 3)
	pwv := &wv
	CheckI("pwv", pwv, 3)
	CheckF("pwv.M", pwv.M, 3)
	CheckF("(*pwv).M", (*pwv).M, 3)

	wp := Twordp(4)
	CheckI("&wp", &wp, 4)
	CheckF("wp.M", wp.M, 4)
	CheckF("(&wp).M", (&wp).M, 4)
	pwp := &wp
	CheckI("pwp", pwp, 4)
	CheckF("pwp.M", pwp.M, 4)
	CheckF("(*pwp).M", (*pwp).M, 4)

	bv := Tbigv([2]uintptr{5, 6})
	pbv := &bv
	CheckI("bv", bv, 11)
	CheckF("bv.M", bv.M, 11)
	CheckF("(&bv).M", (&bv).M, 11)
	CheckI("pbv", pbv, 11)
	CheckF("pbv.M", pbv.M, 11)
	CheckF("(*pbv).M", (*pbv).M, 11)
	
	bp := Tbigp([2]uintptr{7,8})
	CheckI("&bp", &bp, 15)
	CheckF("bp.M", bp.M, 15)
	CheckF("(&bp).M", (&bp).M, 15)
	pbp := &bp
	CheckI("pbp", pbp, 15)
	CheckF("pbp.M", pbp.M, 15)
	CheckF("(*pbp).M", (*pbp).M, 15)

	_sv := tsmallv(1)
	checkI("_sv", _sv, 1)
	checkF("_sv.m", _sv.m, 1)
	checkF("(&_sv).m", (&_sv).m, 1)
	_psv := &_sv
	checkI("_psv", _psv, 1)
	checkF("_psv.m", _psv.m, 1)
	checkF("(*_psv).m", (*_psv).m, 1)

	_sp := tsmallp(2)
	checkI("&_sp", &_sp, 2)
	checkF("_sp.m", _sp.m, 2)
	checkF("(&_sp).m", (&_sp).m, 2)
	_psp := &_sp
	checkI("_psp", _psp, 2)
	checkF("_psp.m", _psp.m, 2)
	checkF("(*_psp).m", (*_psp).m, 2)

	_wv := twordv(3)
	checkI("_wv", _wv, 3)
	checkF("_wv.m", _wv.m, 3)
	checkF("(&_wv).m", (&_wv).m, 3)
	_pwv := &_wv
	checkI("_pwv", _pwv, 3)
	checkF("_pwv.m", _pwv.m, 3)
	checkF("(*_pwv).m", (*_pwv).m, 3)

	_wp := twordp(4)
	checkI("&_wp", &_wp, 4)
	checkF("_wp.m", _wp.m, 4)
	checkF("(&_wp).m", (&_wp).m, 4)
	_pwp := &_wp
	checkI("_pwp", _pwp, 4)
	checkF("_pwp.m", _pwp.m, 4)
	checkF("(*_pwp).m", (*_pwp).m, 4)

	_bv := tbigv([2]uintptr{5, 6})
	_pbv := &_bv
	checkI("_bv", _bv, 11)
	checkF("_bv.m", _bv.m, 11)
	checkF("(&_bv).m", (&_bv).m, 11)
	checkI("_pbv", _pbv, 11)
	checkF("_pbv.m", _pbv.m, 11)
	checkF("(*_pbv).m", (*_pbv).m, 11)
	
	_bp := tbigp([2]uintptr{7,8})
	checkI("&_bp", &_bp, 15)
	checkF("_bp.m", _bp.m, 15)
	checkF("(&_bp).m", (&_bp).m, 15)
	_pbp := &_bp
	checkI("_pbp", _pbp, 15)
	checkF("_pbp.m", _pbp.m, 15)
	checkF("(*_pbp).m", (*_pbp).m, 15)
	
	t4 := T4{}
	t3 := T3{&t4}
	t2 := T2{&t3}
	t1 := T1{t2}
	CheckI("t4", t4, 40)
	CheckI("&t4", &t4, 40)
	CheckI("t3", t3, 40)
	CheckI("&t3", &t3, 40)
	CheckI("t2", t2, 40)
	CheckI("&t2", &t2, 40)
	CheckI("t1", t1, 40)
	CheckI("&t1", &t1, 40)
	
	// x.M panics if x is an interface type and is nil,
	// or if x.M expands to (*x).M where x is nil,
	// or if x.M expands to x.y.z.w.M where something
	// along the evaluation of x.y.z.w is nil.
	var f func(int, byte) (byte, int)
	shouldPanic(func() { psv = nil; f = psv.M })
	shouldPanic(func() { pwv = nil; f = pwv.M })
	shouldPanic(func() { pbv = nil; f = pbv.M })
	shouldPanic(func() { var i Tinter; f = i.M })
	shouldPanic(func() { _psv = nil; f = _psv.m })
	shouldPanic(func() { _pwv = nil; f = _pwv.m })
	shouldPanic(func() { _pbv = nil; f = _pbv.m })
	shouldPanic(func() { var _i tinter; f = _i.m })
	shouldPanic(func() { var t1 T1; f = t1.M })
	shouldPanic(func() { var t2 T2; f = t2.M })
	shouldPanic(func() { var t3 *T3; f = t3.M })
	shouldPanic(func() { var t3 T3; f = t3.M })

	if f != nil {
		panic("something set f")
	}
	
	// x.M does not panic if x is a nil pointer and
	// M is a method with a pointer receiver.
	shouldNotPanic(func() { psp = nil; f = psp.M })
	shouldNotPanic(func() { pwp = nil; f = pwp.M })
	shouldNotPanic(func() { pbp = nil; f = pbp.M })
	shouldNotPanic(func() { _psp = nil; f = _psp.m })
	shouldNotPanic(func() { _pwp = nil; f = _pwp.m })
	shouldNotPanic(func() { _pbp = nil; f = _pbp.m })
	shouldNotPanic(func() { var t4 T4; f = t4.M })
	if f == nil {
		panic("nothing set f")
	}
}