The build tree state is managed by the `BuildTreeState` class.
An instance is created at the start of a build execution and discarded at the end of the execution.

### Build state

The "build state" holds the state for a build within the build definition for a single build execution, and is contained by the build tree state.

The build state is managed by the `BuildState` class.

        m.region(pos, input.length());
        return m.lookingAt();
    }

    public String region() {
        return input.substring(markPos, pos);
    }

    /**
     * Moves the position to the next instance of the given character, or the end of the input if not found.
     */
    public void find(char c) {
        int cpos = pos;
        while (cpos < input.length()) {
            if (input.charAt(cpos) == c) {

@GwtCompatible
final class Absent<T> extends Optional<T> {
  static final Absent<Object> INSTANCE = new Absent<>();

  @SuppressWarnings("unchecked") // implementation is "fully variant"
  static <T> Optional<T> withType() {
    return (Optional<T>) INSTANCE;
  }

  private Absent() {}

  @Override
  public boolean isPresent() {
    return false;
  }

  @Override

 *
 * @since 4.0.0
 */
@Experimental
@Consumer
public interface ToolchainFactory {
    /**
     * Creates a toolchain instance from the provided model configuration.
     *
     * @param model The toolchain configuration model
     * @return A configured toolchain instance
     * @throws ToolchainFactoryException if toolchain creation fails
     */
    @Nonnull

 * returns a new instance.
 *
 * This collection is optimized for safe concurrent access over a very small number of elements.
 *
 * This collection and is expected to hold fewer than 10 elements. Each operation is _O(N)_, and so
 * building an instance with _N_ elements is _O(N**2)_.
 */
internal sealed class Tags {
  /**

            f.include(PublicApi.INSTANCE.getIncludes());
            // Filter out any non-public APIs
            f.exclude(PublicApi.INSTANCE.getExcludes());
        }));
        extension.getKotlinDslSource().from(sourcesPath.getIncoming().artifactView(v -> v.lenient(true)).getFiles().getAsFileTree().matching(f -> {
            f.include(PublicKotlinDslApi.INSTANCE.getIncludes());
            // Filter out any non-public APIs

 * JUnit constructs the instances.
 *
 * <p>This class is emulated in GWT.
 *
 * @param <G> the type of the test generator required by this tester. An instance of G should
 *     somehow provide an instance of the class under test, plus any other information required to
 *     parameterize the test.
 * @author George van den Driessche
 */
@GwtCompatible
@NullMarked

 * JUnit constructs the instances.
 *
 * <p>This class is emulated in GWT.
 *
 * @param <G> the type of the test generator required by this tester. An instance of G should
 *     somehow provide an instance of the class under test, plus any other information required to
 *     parameterize the test.
 * @author George van den Driessche
 */
@GwtCompatible
@NullMarked

    super(message);
  }

  /**
   * Creates a new instance with the given detail message and cause. Prefer to provide a
   * non-nullable {@code cause}, as many users expect to find one.
   */
  public ExecutionError(@Nullable String message, @Nullable Error cause) {
    super(message, cause);
  }

  /**
   * Creates a new instance with {@code null} as its detail message and the given cause. Prefer to

  public <S extends Comparable<?>> Ordering<S> reverse() {
    return (Ordering<S>) ReverseNaturalOrdering.INSTANCE;
  }

  // preserving singleton-ness gives equals()/hashCode() for free
  private Object readResolve() {
    return INSTANCE;
  }

  @Override
  public String toString() {
    return "Ordering.natural()";
  }

  private NaturalOrdering() {}