// license that can be found in the LICENSE file.

package runtime

// This file contains the implementation of Go select statements.

import (
	"internal/abi"
	"unsafe"
)

const debugSelect = false

// Select case descriptor.
// Known to compiler.
// Changes here must also be made in src/cmd/compile/internal/walk/select.go's scasetype.
type scase struct {
	c    *hchan         // chan
	elem unsafe.Pointer // data element
}

		switch c.Dir {
		default:
			panic("reflect.Select: invalid Dir")

		case SelectDefault: // default
			if haveDefault {
				panic("reflect.Select: multiple default cases")
			}
			haveDefault = true
			if c.Chan.IsValid() {
				panic("reflect.Select: default case has Chan value")
			}
			if c.Send.IsValid() {
				panic("reflect.Select: default case has Send value")
			}

package clause

// Select select attrs when querying, updating, creating
type Select struct {
	Distinct   bool
	Columns    []Column
	Expression Expression
}

func (s Select) Name() string {
	return "SELECT"
}

func (s Select) Build(builder Builder) {
	if len(s.Columns) > 0 {
		if s.Distinct {
			builder.WriteString("DISTINCT ")
		}

		for idx, column := range s.Columns {
			if idx > 0 {
				builder.WriteByte(',')

	// optimization: zero-case select
	if ncas == 0 {
		return []ir.Node{mkcallstmt("block")}
	}

	// optimization: one-case select: single op.
	if ncas == 1 {
		cas := cases[0]
		ir.SetPos(cas)
		l := cas.Init()
		if cas.Comm != nil { // not default:
			n := cas.Comm
			l = append(l, ir.TakeInit(n)...)
			switch n.Op() {
			default:
				base.Fatalf("select %v", n.Op())

			case ir.OSEND:

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Test simple select.

package main

var counter uint
var shift uint

func GetValue() uint {
	counter++
	return 1 << shift
}

func Send(a, b chan uint) int {
	var i int

LOOP:
	for {
		select {
		case a <- GetValue():
			i++
			a = nil
		case b <- GetValue():
			i++
			b = nil
		default:

// license that can be found in the LICENSE file.

package codegen

func f() {
	ch1 := make(chan int)
	ch2 := make(chan int)
	for {
		// amd64:-`MOVQ\t[$]0, command-line-arguments..autotmp_3`
		select {
		case <-ch1:
		case <-ch2:
		default:
		}
	}

                  region_name='us-east-1')

r = s3.select_object_content(
    Bucket='mycsvbucket',
    Key='sampledata/TotalPopulation.csv.gz',
    ExpressionType='SQL',
    Expression="select * from s3object s where s.Location like '%United States%'",
    InputSerialization={
        'CSV': {
            "FileHeaderInfo": "USE",
        },
        'CompressionType': 'GZIP',
    },

		}
	})

	// selects with closed channels behave like ordinary operations
	testBlock(never, func() {
		select {
		case <-closedch:
		}
	})
	testBlock(never, func() {
		select {
		case x := (<-closedch):
			_ = x
		}
	})
	testBlock(never, func() {
		select {
		case x, ok := (<-closedch):
			_, _ = x, ok
		}
	})
	testPanic(always, func() {
		select {
		case closedch <- 7:

	order = 0
	c <- n
	{{if .Maybe}}
	{{/*  Outside of select, left-to-right rule applies. */}}
	{{/*  (Inside select, assignment waits until case is chosen, */}}
	{{/*  so right hand side happens before anything on left hand side. */}}
	*fp(&x, 1) = <-fc(c, 2)
	{{else}}{{if .Maybe}}
	m[fn(13, 1)] = <-fc(c, 2)
	x = m[13]
	{{else}}
	select {
	{{/*  Blocking or non-blocking, before the receive. */}}

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Test for select: Issue 2075
// A bug in select corrupts channel queues of failed cases
// if there are multiple waiters on those channels and the
// select is the last in the queue. If further waits are made
// on the channel without draining it first then those waiters