import java.util.concurrent.Executor;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/** Implementations of {@code Futures.transform*}. */
@GwtCompatible
@ElementTypesAreNonnullByDefault
@SuppressWarnings("nullness") // TODO(b/147136275): Remove once our checker understands & and |.
abstract class AbstractTransformFuture<

    public T get() {
      // A 2-field variant of Double Checked Locking.
      if (!initialized) {
        synchronized (this) {
          if (!initialized) {
            T t = delegate.get();
            value = t;
            initialized = true;
            return t;
          }
        }
      }
      // This is safe because we checked `initialized`.
      return uncheckedCastNullableTToT(value);
    }

// path of named types in a cycle, it is only needed for error reporting.
func (check *Checker) validType0(pos syntax.Pos, typ Type, nest, path []*Named) bool {
	typ = Unalias(typ)

	if check.conf.Trace {
		if t, _ := typ.(*Named); t != nil && t.obj != nil /* obj should always exist but be conservative */ {
			pos = t.obj.pos
		}
		check.indent++

// path of named types in a cycle, it is only needed for error reporting.
func (check *Checker) validType0(pos token.Pos, typ Type, nest, path []*Named) bool {
	typ = Unalias(typ)

	if check.conf._Trace {
		if t, _ := typ.(*Named); t != nil && t.obj != nil /* obj should always exist but be conservative */ {
			pos = t.obj.pos
		}
		check.indent++

		x.typ = Typ[Invalid]
	}

	check.index(index, length)
	return false
}

func (check *Checker) sliceExpr(x *operand, e *syntax.SliceExpr) {
	check.expr(nil, x, e.X)
	if x.mode == invalid {
		check.use(e.Index[:]...)
		return
	}

	valid := false
	length := int64(-1) // valid if >= 0
	switch u := coreString(x.typ).(type) {
	case nil:

		x.typ = Typ[Invalid]
	}

	check.index(index, length)
	return false
}

func (check *Checker) sliceExpr(x *operand, e *ast.SliceExpr) {
	check.expr(nil, x, e.X)
	if x.mode == invalid {
		check.use(e.Low, e.High, e.Max)
		return
	}

	valid := false
	length := int64(-1) // valid if >= 0
	switch u := coreString(x.typ).(type) {
	case nil:

    public T get() {
      // A 2-field variant of Double Checked Locking.
      if (!initialized) {
        synchronized (this) {
          if (!initialized) {
            T t = delegate.get();
            value = t;
            initialized = true;
            return t;
          }
        }
      }
      // This is safe because we checked `initialized`.
      return uncheckedCastNullableTToT(value);
    }

If the "dump" flag is specified, the output is written on a file named
<phase>__<function_name>_<seq>.dump; otherwise it is directed to stdout.

Examples:

    -d=ssa/check/on
enables checking after each phase

	-d=ssa/check/seed=1234
enables checking after each phase, using 1234 to seed the PRNG
used for value order randomization

    -d=ssa/all/time
enables time reporting for all phases

    -d=ssa/prove/debug=2

	"os"
	"os/exec"
	"path/filepath"
	"reflect"
	"runtime"
	"strings"
)

// Partial type checker.
//
// The fact that it is partial is very important: the input is
// an AST and a description of some type information to
// assume about one or more packages, but not all the
// packages that the program imports. The checker is
// expected to do as much as it can with what it has been

		// baseline 1, basebits 0, and one entry that is baseline 2,
		// basebits 1. All other entries will have baseline >= 4
		// basebits >= 2.
		//
		// So we can check for RFC offset <= 3 by checking for
		// basebits <= 1. That means that we can subtract 3 here
		// and not worry about doing it in the hot loop.

		be.baseline = 1 << e.sym
		if e.sym >= 2 {
			be.baseline -= 3
		}