// Copyright 2021 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 noder

import (
	"cmd/compile/internal/ir"
	"cmd/compile/internal/syntax"
)

// TODO(mdempsky): Investigate replacing with switch statements or dense arrays.

var branchOps = [...]ir.Op{
	syntax.Break:       ir.OBREAK,
	syntax.Continue:    ir.OCONTINUE,
	syntax.Fallthrough: ir.OFALL,
	syntax.Goto:        ir.OGOTO,
}

var callOps = [...]ir.Op{
	syntax.Defer: ir.ODEFER,
	syntax.Go:    ir.OGO,
}

// initDefn marks the given names as declared by defn and populates
// its Init field with ODCL nodes. It then reports whether any names
// were so declared, which can be used to initialize defn.Def.
func initDefn(defn ir.InitNode, names []*ir.Name) bool {
	if len(names) == 0 {
		return false
	}

	init := make([]ir.Node, len(names))
	for i, name := range names {
		name.Defn = defn
		init[i] = ir.NewDecl(name.Pos(), ir.ODCL, name)
	}
	defn.SetInit(init)
	return true
}

// unpackTwo returns the first two nodes in list. If list has fewer
// than 2 nodes, then the missing nodes are replaced with nils.
func unpackTwo(list []ir.Node) (fst, snd ir.Node) {
	switch len(list) {
	case 0:
		return nil, nil
	case 1:
		return list[0], nil
	default:
		return list[0], list[1]
	}
}