src/main/java/com/google/devtools/build/lib/packages/StarlarkInfoWithSchema.java - bazel - Git at Google

 // Copyright 2023 The Bazel Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //    http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 package com.google.devtools.build.lib.packages;

 import com.google.common.base.Joiner;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Interner;
 import com.google.devtools.build.lib.collect.nestedset.Depset;
 import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 import com.google.devtools.build.lib.concurrent.BlazeInterners;
 import com.google.devtools.build.lib.skyframe.serialization.VisibleForSerialization;
 import com.google.devtools.build.lib.util.HashCodes;
 import com.google.errorprone.annotations.ForOverride;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import javax.annotation.Nullable;
 import net.starlark.java.eval.Compactable;
 import net.starlark.java.eval.EvalException;
 import net.starlark.java.eval.Starlark;
 import net.starlark.java.eval.StarlarkFloat;
 import net.starlark.java.eval.StarlarkThread;
 import net.starlark.java.syntax.TokenKind;

 /**
  * A struct-like Info (provider instance) for providers defined in Starlark that have a schema.
  *
  * <p>Maintainer's note: This class is memory-optimized in a way that can cause profiling
  * instability in some pathological cases. See {@link StarlarkProvider#maybeUnwrapDepset} for more
  * information.
  *
  * <p>Schemas with <= 5 fields (covering the majority of provider types in practice) each have their
  * own dedicated subclass to optimize for memory by forgoing an array.
  */
 public abstract sealed class StarlarkInfoWithSchema extends StarlarkInfo {

   /**
    * Interner for {@linkplain #isInternable internable} instances.
    *
    * <p>Interning is limited to instances without truthy values for two reasons:
    *
    * <ol>
    *   <li>This covers the most frequent category of duplicates in practice. Interning further may
    *       not be worth the cost.
    *   <li>Hashing truthy values can be arbitrarily expensive and potentially even dangerous due to
    *       the possibility of object graph cycles.
    * </ol>
    */
   private static final Interner<StarlarkInfoWithSchema> interner = BlazeInterners.newWeakInterner();

   private final StarlarkProvider provider;

   private StarlarkInfoWithSchema(StarlarkProvider provider) {
     this.provider = provider;
   }

   @Override
   public final Provider getProvider() {
     return provider;
   }

   @ForOverride
   abstract Object getValueAt(int i);

   @ForOverride
   abstract void setValueAt(int i, Object val);

   @VisibleForSerialization
   Object[] getValuesForSerialization() {
     int n = provider.getFields().size();
     Object[] table = new Object[n];
     for (int i = 0; i < n; i++) {
       table[i] = getValueAt(i);
     }
     return table;
   }

   @VisibleForSerialization
   static StarlarkInfoWithSchema create(StarlarkProvider provider, Object[] vs) {
     return switch (vs.length) {
       case 0 -> new Schema0(provider);
       case 1 -> new Schema1(provider, vs[0]);
       case 2 -> new Schema2(provider, vs[0], vs[1]);
       case 3 -> new Schema3(provider, vs[0], vs[1], vs[2]);
       case 4 -> new Schema4(provider, vs[0], vs[1], vs[2], vs[3]);
       case 5 -> new Schema5(provider, vs[0], vs[1], vs[2], vs[3], vs[4]);
       default -> new SchemaN(provider, vs);
     };
   }

   static StarlarkProvider.StarlarkInfoFactory newStarlarkInfoFactory(
       StarlarkProvider provider, StarlarkThread thread) {
     return new StarlarkInfoFactory(provider, thread);
   }

   /**
    * Constructs a StarlarkInfo with calls forwarded from one of the StarlarkInfo ArgumentProcessor
    * implementations. Checks that each key is provided at most once, and is defined by the schema,
    * which must be sorted. This class exists solely for the StarlarkInfo ArgumentProcessors.
    */
   static final class StarlarkInfoFactory extends StarlarkProvider.StarlarkInfoFactory {
     private final ImmutableMap<String, Integer> fields;
     private final Object[] valueTable;
     private List<String> unexpected;

     StarlarkInfoFactory(StarlarkProvider provider, StarlarkThread thread) {
       super(provider, thread);
       this.fields = provider.getFields();
       this.valueTable = new Object[fields.size()];
       this.unexpected = null;
     }

     @Override
     public void addNamedArg(String name, Object value) throws EvalException {
       int pos = indexOfField(name, fields);
       if (pos >= 0) {
         if (valueTable[pos] != null) {
           throw Starlark.errorf(
               "got multiple values for parameter %s in call to instantiate provider %s",
               name, provider.getPrintableName());
         }
         valueTable[pos] =
             value instanceof Depset depset ? provider.maybeUnwrapDepset(pos, depset) : value;
       } else {
         if (unexpected == null) {
           unexpected = new ArrayList<>();
         }
         unexpected.add(name);
       }
     }

     @Override
     public StarlarkInfoWithSchema createFromArgs() throws EvalException {
       if (unexpected != null) {
         throw Starlark.errorf(
             "got unexpected field%s '%s' in call to instantiate provider %s",
             unexpected.size() > 1 ? "s" : "",
             Joiner.on("', '").join(unexpected),
             provider.getPrintableName());
       }
       return create(provider, valueTable);
     }

     @Override
     public StarlarkInfo createFromMap(Map<String, Object> map) throws EvalException {
       for (Map.Entry<String, Object> e : map.entrySet()) {
         addNamedArg(e.getKey(), e.getValue());
       }
       return createFromArgs();
     }
   }

   @Override
   public final ImmutableList<String> getFieldNames() {
     ImmutableList.Builder<String> fieldNames = new ImmutableList.Builder<>();
     int i = 0;
     for (String field : provider.getFields().keySet()) {
       if (getValueAt(i) != null) {
         fieldNames.add(field);
       }
       i++;
     }
     return fieldNames.build();
   }

   @Override
   public final boolean isImmutable() {
     // If the provider is not yet exported, the hash code of the object is subject to change.
     if (!provider.isExported()) {
       return false;
     }
     int n = provider.getFields().size();
     for (int i = 0; i < n; i++) {
       Object val = getValueAt(i);
       // Unwrapped depsets (NestedSets) are not Starlark values, but are immutable.
       if (val != null && !(val instanceof NestedSet<?> || Starlark.isImmutable(val))) {
         return false;
       }
     }
     return true;
   }

   @Nullable
   @Override
   public final Object getValue(String name) {
     ImmutableMap<String, Integer> fields = provider.getFields();
     int i = indexOfField(name, fields);
     if (i < 0) {
       return null;
     }
     Object val = getValueAt(i);
     return val instanceof NestedSet<?> nestedSet ? provider.rewrapDepset(i, nestedSet) : val;
   }

   @Nullable
   @Override
   public final StarlarkInfoWithSchema binaryOp(TokenKind op, Object that, boolean thisLeft)
       throws EvalException {
     if (op == TokenKind.PLUS && that instanceof StarlarkInfo thatInfo) {
       Provider thatProvider = thatInfo.getProvider();
       if (!provider.equals(thatProvider)) {
         throw Starlark.errorf(
             "Cannot use '+' operator on instances of different providers (%s and %s)",
             provider.getPrintableName(), thatProvider.getPrintableName());
       }
       Preconditions.checkArgument(thatInfo instanceof StarlarkInfoWithSchema, thatInfo);
       return thisLeft
           ? plus(this, (StarlarkInfoWithSchema) that) //
           : plus((StarlarkInfoWithSchema) that, this);
     }
     return null;
   }

   private static StarlarkInfoWithSchema plus(StarlarkInfoWithSchema x, StarlarkInfoWithSchema y)
       throws EvalException {
     int n = x.provider.getFields().size();

     Object[] ztable = new Object[n];
     for (int i = 0; i < n; i++) {
       Object xVal = x.getValueAt(i);
       Object yVal = y.getValueAt(i);
       if (xVal != null && yVal != null) {
         ImmutableMap<String, Integer> schema = x.provider.getFields();
         throw Starlark.errorf(
             "cannot add struct instances with common field '%s'", schema.keySet().asList().get(i));
       }
       ztable[i] = xVal != null ? xVal : yVal;
     }
     return create(x.provider, ztable);
   }

   @Override
   public final StarlarkInfoWithSchema unsafeOptimizeMemoryLayout() {
     boolean internable = true;
     int n = provider.getFields().size();
     for (int i = 0; i < n; i++) {
       Object val = getValueAt(i);
       internable = internable && valueIsInternable(val);
       if (val instanceof Compactable compactable) {
         setValueAt(i, compactable.unsafeOptimizeMemoryLayout());
       }
     }
     return internable ? interner.intern(this) : this;
   }

   /**
    * Returns true if this instance is internable (i.e. it contains only values that are considered
    * internable).
    *
    * <p>Internable instances are guaranteed to contain no object reference cycles, so they can be
    * interned by value equality.
    */
   final boolean isInternable() {
     int n = provider.getFields().size();
     for (int i = 0; i < n; i++) {
       if (!valueIsInternable(getValueAt(i))) {
         return false;
       }
     }
     return true;
   }

   /**
    * A value is considered internable if its {@linkplain Starlark#truth truthiness} is false (except
    * for {@link StarlarkFloat} values, which are never internable), or it is an empty {@link
    * NestedSet}, or a {@code null}.
    */
   private static boolean valueIsInternable(@Nullable Object val) {
     return switch (val) {
       case NestedSet<?> nestedSet -> nestedSet.isEmpty();
       // ``+0.0`, `-0.0`, and `0` are all `equals()` but have different memory representations.
       case StarlarkFloat sf -> false;
       case null -> true;
       default -> !Starlark.truth(val);
     };
   }

   /** Returns the index of the given named field in the given map of fields, or -1 if not found. */
   private static int indexOfField(String name, ImmutableMap<String, Integer> fields) {
     Integer idx = fields.get(name);
     return idx != null ? idx : -1;
   }

   /** For providers with no fields. */
   private static final class Schema0 extends StarlarkInfoWithSchema {
     Schema0(StarlarkProvider provider) {
       super(provider);
     }

     @Override
     Object getValueAt(int i) {
       throw new IndexOutOfBoundsException(i);
     }

     @Override
     void setValueAt(int i, Object val) {
       throw new IndexOutOfBoundsException(i);
     }

     @Override
     public int hashCode() {
       return 31 * getProvider().hashCode() + 1;
     }

     @Override
     public boolean equals(Object o) {
       if (this == o) {
         return true;
       }
       if (!(o instanceof Schema0 other)) {
         return false;
       }
       return getProvider().equals(other.getProvider());
     }
   }

   /** For providers with 1 field. */
   private static final class Schema1 extends StarlarkInfoWithSchema {
     private Object v0;

     Schema1(StarlarkProvider provider, Object v0) {
       super(provider);
       this.v0 = v0;
     }

     @Override
     Object getValueAt(int i) {
       if (i == 0) {
         return v0;
       }
       throw new IndexOutOfBoundsException(i);
     }

     @Override
     void setValueAt(int i, Object val) {
       if (i == 0) {
         this.v0 = val;
         return;
       }
       throw new IndexOutOfBoundsException(i);
     }

     @Override
     public int hashCode() {
       return HashCodes.hashObjects(getProvider(), v0);
     }

     @Override
     public boolean equals(Object o) {
       if (this == o) {
         return true;
       }
       if (!(o instanceof Schema1 other)) {
         return false;
       }
       return getProvider().equals(other.getProvider()) && Objects.equals(v0, other.v0);
     }
   }

   /** For providers with 2 fields. */
   private static final class Schema2 extends StarlarkInfoWithSchema {
     private Object v0;
     private Object v1;

     Schema2(StarlarkProvider provider, Object v0, Object v1) {
       super(provider);
       this.v0 = v0;
       this.v1 = v1;
     }

     @Override
     Object getValueAt(int i) {
       return switch (i) {
         case 0 -> v0;
         case 1 -> v1;
         default -> throw new IndexOutOfBoundsException(i);
       };
     }

     @Override
     void setValueAt(int i, Object val) {
       switch (i) {
         case 0 -> this.v0 = val;
         case 1 -> this.v1 = val;
         default -> throw new IndexOutOfBoundsException(i);
       }
     }

     @Override
     public int hashCode() {
       return HashCodes.hashObjects(getProvider(), v0, v1);
     }

     @Override
     public boolean equals(Object o) {
       if (this == o) {
         return true;
       }
       if (!(o instanceof Schema2 other)) {
         return false;
       }
       return getProvider().equals(other.getProvider())
           && Objects.equals(v0, other.v0)
           && Objects.equals(v1, other.v1);
     }
   }

   /** For providers with 3 fields. */
   private static final class Schema3 extends StarlarkInfoWithSchema {
     private Object v0;
     private Object v1;
     private Object v2;

     Schema3(StarlarkProvider provider, Object v0, Object v1, Object v2) {
       super(provider);
       this.v0 = v0;
       this.v1 = v1;
       this.v2 = v2;
     }

     @Override
     Object getValueAt(int i) {
       return switch (i) {
         case 0 -> v0;
         case 1 -> v1;
         case 2 -> v2;
         default -> throw new IndexOutOfBoundsException(i);
       };
     }

     @Override
     void setValueAt(int i, Object val) {
       switch (i) {
         case 0 -> this.v0 = val;
         case 1 -> this.v1 = val;
         case 2 -> this.v2 = val;
         default -> throw new IndexOutOfBoundsException(i);
       }
     }

     @Override
     public int hashCode() {
       return HashCodes.hashObjects(getProvider(), v0, v1, v2);
     }

     @Override
     public boolean equals(Object o) {
       if (this == o) {
         return true;
       }
       if (!(o instanceof Schema3 other)) {
         return false;
       }
       return getProvider().equals(other.getProvider())
           && Objects.equals(v0, other.v0)
           && Objects.equals(v1, other.v1)
           && Objects.equals(v2, other.v2);
     }
   }

   /** For providers with 4 fields. */
   private static final class Schema4 extends StarlarkInfoWithSchema {
     private Object v0;
     private Object v1;
     private Object v2;
     private Object v3;

     Schema4(StarlarkProvider provider, Object v0, Object v1, Object v2, Object v3) {
       super(provider);
       this.v0 = v0;
       this.v1 = v1;
       this.v2 = v2;
       this.v3 = v3;
     }

     @Override
     Object getValueAt(int i) {
       return switch (i) {
         case 0 -> v0;
         case 1 -> v1;
         case 2 -> v2;
         case 3 -> v3;
         default -> throw new IndexOutOfBoundsException(i);
       };
     }

     @Override
     void setValueAt(int i, Object val) {
       switch (i) {
         case 0 -> this.v0 = val;
         case 1 -> this.v1 = val;
         case 2 -> this.v2 = val;
         case 3 -> this.v3 = val;
         default -> throw new IndexOutOfBoundsException(i);
       }
     }

     @Override
     public int hashCode() {
       return HashCodes.hashObjects(getProvider(), v0, v1, v2, v3);
     }

     @Override
     public boolean equals(Object o) {
       if (this == o) {
         return true;
       }
       if (!(o instanceof Schema4 other)) {
         return false;
       }
       return getProvider().equals(other.getProvider())
           && Objects.equals(v0, other.v0)
           && Objects.equals(v1, other.v1)
           && Objects.equals(v2, other.v2)
           && Objects.equals(v3, other.v3);
     }
   }

   /** For providers with 5 fields. */
   private static final class Schema5 extends StarlarkInfoWithSchema {
     private Object v0;
     private Object v1;
     private Object v2;
     private Object v3;
     private Object v4;

     Schema5(StarlarkProvider provider, Object v0, Object v1, Object v2, Object v3, Object v4) {
       super(provider);
       this.v0 = v0;
       this.v1 = v1;
       this.v2 = v2;
       this.v3 = v3;
       this.v4 = v4;
     }

     @Override
     Object getValueAt(int i) {
       return switch (i) {
         case 0 -> v0;
         case 1 -> v1;
         case 2 -> v2;
         case 3 -> v3;
         case 4 -> v4;
         default -> throw new IndexOutOfBoundsException(i);
       };
     }

     @Override
     void setValueAt(int i, Object val) {
       switch (i) {
         case 0 -> this.v0 = val;
         case 1 -> this.v1 = val;
         case 2 -> this.v2 = val;
         case 3 -> this.v3 = val;
         case 4 -> this.v4 = val;
         default -> throw new IndexOutOfBoundsException(i);
       }
     }

     @Override
     public int hashCode() {
       return HashCodes.hashObjects(getProvider(), v0, v1, v2, v3, v4);
     }

     @Override
     public boolean equals(Object o) {
       if (this == o) {
         return true;
       }
       if (!(o instanceof Schema5 other)) {
         return false;
       }
       return getProvider().equals(other.getProvider())
           && Objects.equals(v0, other.v0)
           && Objects.equals(v1, other.v1)
           && Objects.equals(v2, other.v2)
           && Objects.equals(v3, other.v3)
           && Objects.equals(v4, other.v4);
     }
   }

   /** For providers with 6 or more fields. */
   private static final class SchemaN extends StarlarkInfoWithSchema {
     private final Object[] vs;

     SchemaN(StarlarkProvider provider, Object[] vs) {
       super(provider);
       this.vs = vs;
     }

     @Override
     Object getValueAt(int i) {
       return vs[i];
     }

     @Override
     void setValueAt(int i, Object val) {
       vs[i] = val;
     }

     @Override
     Object[] getValuesForSerialization() {
       return vs;
     }

     @Override
     public int hashCode() {
       return 31 * getProvider().hashCode() + Arrays.hashCode(vs);
     }

     @Override
     public boolean equals(Object o) {
       if (this == o) {
         return true;
       }
       if (!(o instanceof SchemaN other)) {
         return false;
       }
       return getProvider().equals(other.getProvider()) && Arrays.equals(vs, other.vs);
     }
   }
 }
	// Copyright 2023 The Bazel Authors. All rights reserved.
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	package com.google.devtools.build.lib.packages;

	import com.google.common.base.Joiner;
	import com.google.common.base.Preconditions;
	import com.google.common.collect.ImmutableList;
	import com.google.common.collect.ImmutableMap;
	import com.google.common.collect.Interner;
	import com.google.devtools.build.lib.collect.nestedset.Depset;
	import com.google.devtools.build.lib.collect.nestedset.NestedSet;
	import com.google.devtools.build.lib.concurrent.BlazeInterners;
	import com.google.devtools.build.lib.skyframe.serialization.VisibleForSerialization;
	import com.google.devtools.build.lib.util.HashCodes;
	import com.google.errorprone.annotations.ForOverride;
	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.List;
	import java.util.Map;
	import java.util.Objects;
	import javax.annotation.Nullable;
	import net.starlark.java.eval.Compactable;
	import net.starlark.java.eval.EvalException;
	import net.starlark.java.eval.Starlark;
	import net.starlark.java.eval.StarlarkFloat;
	import net.starlark.java.eval.StarlarkThread;
	import net.starlark.java.syntax.TokenKind;

	/**
	* A struct-like Info (provider instance) for providers defined in Starlark that have a schema.
	*
	* <p>Maintainer's note: This class is memory-optimized in a way that can cause profiling
	* instability in some pathological cases. See {@link StarlarkProvider#maybeUnwrapDepset} for more
	* information.
	*
	* <p>Schemas with <= 5 fields (covering the majority of provider types in practice) each have their
	* own dedicated subclass to optimize for memory by forgoing an array.
	*/
	public abstract sealed class StarlarkInfoWithSchema extends StarlarkInfo {

	/**
	* Interner for {@linkplain #isInternable internable} instances.
	*
	* <p>Interning is limited to instances without truthy values for two reasons:
	*
	* <ol>
	* <li>This covers the most frequent category of duplicates in practice. Interning further may
	* not be worth the cost.
	* <li>Hashing truthy values can be arbitrarily expensive and potentially even dangerous due to
	* the possibility of object graph cycles.
	* </ol>
	*/
	private static final Interner<StarlarkInfoWithSchema> interner = BlazeInterners.newWeakInterner();

	private final StarlarkProvider provider;

	private StarlarkInfoWithSchema(StarlarkProvider provider) {
	this.provider = provider;
	}

	@Override
	public final Provider getProvider() {
	return provider;
	}

	@ForOverride
	abstract Object getValueAt(int i);

	@ForOverride
	abstract void setValueAt(int i, Object val);

	@VisibleForSerialization
	Object[] getValuesForSerialization() {
	int n = provider.getFields().size();
	Object[] table = new Object[n];
	for (int i = 0; i < n; i++) {
	table[i] = getValueAt(i);
	}
	return table;
	}

	@VisibleForSerialization
	static StarlarkInfoWithSchema create(StarlarkProvider provider, Object[] vs) {
	return switch (vs.length) {
	case 0 -> new Schema0(provider);
	case 1 -> new Schema1(provider, vs[0]);
	case 2 -> new Schema2(provider, vs[0], vs[1]);
	case 3 -> new Schema3(provider, vs[0], vs[1], vs[2]);
	case 4 -> new Schema4(provider, vs[0], vs[1], vs[2], vs[3]);
	case 5 -> new Schema5(provider, vs[0], vs[1], vs[2], vs[3], vs[4]);
	default -> new SchemaN(provider, vs);
	};
	}

	static StarlarkProvider.StarlarkInfoFactory newStarlarkInfoFactory(
	StarlarkProvider provider, StarlarkThread thread) {
	return new StarlarkInfoFactory(provider, thread);
	}

	/**
	* Constructs a StarlarkInfo with calls forwarded from one of the StarlarkInfo ArgumentProcessor
	* implementations. Checks that each key is provided at most once, and is defined by the schema,
	* which must be sorted. This class exists solely for the StarlarkInfo ArgumentProcessors.
	*/
	static final class StarlarkInfoFactory extends StarlarkProvider.StarlarkInfoFactory {
	private final ImmutableMap<String, Integer> fields;
	private final Object[] valueTable;
	private List<String> unexpected;

	StarlarkInfoFactory(StarlarkProvider provider, StarlarkThread thread) {
	super(provider, thread);
	this.fields = provider.getFields();
	this.valueTable = new Object[fields.size()];
	this.unexpected = null;
	}

	@Override
	public void addNamedArg(String name, Object value) throws EvalException {
	int pos = indexOfField(name, fields);
	if (pos >= 0) {
	if (valueTable[pos] != null) {
	throw Starlark.errorf(
	"got multiple values for parameter %s in call to instantiate provider %s",
	name, provider.getPrintableName());
	}
	valueTable[pos] =
	value instanceof Depset depset ? provider.maybeUnwrapDepset(pos, depset) : value;
	} else {
	if (unexpected == null) {
	unexpected = new ArrayList<>();
	}
	unexpected.add(name);
	}
	}

	@Override
	public StarlarkInfoWithSchema createFromArgs() throws EvalException {
	if (unexpected != null) {
	throw Starlark.errorf(
	"got unexpected field%s '%s' in call to instantiate provider %s",
	unexpected.size() > 1 ? "s" : "",
	Joiner.on("', '").join(unexpected),
	provider.getPrintableName());
	}
	return create(provider, valueTable);
	}

	@Override
	public StarlarkInfo createFromMap(Map<String, Object> map) throws EvalException {
	for (Map.Entry<String, Object> e : map.entrySet()) {
	addNamedArg(e.getKey(), e.getValue());
	}
	return createFromArgs();
	}
	}

	@Override
	public final ImmutableList<String> getFieldNames() {
	ImmutableList.Builder<String> fieldNames = new ImmutableList.Builder<>();
	int i = 0;
	for (String field : provider.getFields().keySet()) {
	if (getValueAt(i) != null) {
	fieldNames.add(field);
	}
	i++;
	}
	return fieldNames.build();
	}

	@Override
	public final boolean isImmutable() {
	// If the provider is not yet exported, the hash code of the object is subject to change.
	if (!provider.isExported()) {
	return false;
	}
	int n = provider.getFields().size();
	for (int i = 0; i < n; i++) {
	Object val = getValueAt(i);
	// Unwrapped depsets (NestedSets) are not Starlark values, but are immutable.
	if (val != null && !(val instanceof NestedSet<?> \|\| Starlark.isImmutable(val))) {
	return false;
	}
	}
	return true;
	}

	@Nullable
	@Override
	public final Object getValue(String name) {
	ImmutableMap<String, Integer> fields = provider.getFields();
	int i = indexOfField(name, fields);
	if (i < 0) {
	return null;
	}
	Object val = getValueAt(i);
	return val instanceof NestedSet<?> nestedSet ? provider.rewrapDepset(i, nestedSet) : val;
	}

	@Nullable
	@Override
	public final StarlarkInfoWithSchema binaryOp(TokenKind op, Object that, boolean thisLeft)
	throws EvalException {
	if (op == TokenKind.PLUS && that instanceof StarlarkInfo thatInfo) {
	Provider thatProvider = thatInfo.getProvider();
	if (!provider.equals(thatProvider)) {
	throw Starlark.errorf(
	"Cannot use '+' operator on instances of different providers (%s and %s)",
	provider.getPrintableName(), thatProvider.getPrintableName());
	}
	Preconditions.checkArgument(thatInfo instanceof StarlarkInfoWithSchema, thatInfo);
	return thisLeft
	? plus(this, (StarlarkInfoWithSchema) that) //
	: plus((StarlarkInfoWithSchema) that, this);
	}
	return null;
	}

	private static StarlarkInfoWithSchema plus(StarlarkInfoWithSchema x, StarlarkInfoWithSchema y)
	throws EvalException {
	int n = x.provider.getFields().size();

	Object[] ztable = new Object[n];
	for (int i = 0; i < n; i++) {
	Object xVal = x.getValueAt(i);
	Object yVal = y.getValueAt(i);
	if (xVal != null && yVal != null) {
	ImmutableMap<String, Integer> schema = x.provider.getFields();
	throw Starlark.errorf(
	"cannot add struct instances with common field '%s'", schema.keySet().asList().get(i));
	}
	ztable[i] = xVal != null ? xVal : yVal;
	}
	return create(x.provider, ztable);
	}

	@Override
	public final StarlarkInfoWithSchema unsafeOptimizeMemoryLayout() {
	boolean internable = true;
	int n = provider.getFields().size();
	for (int i = 0; i < n; i++) {
	Object val = getValueAt(i);
	internable = internable && valueIsInternable(val);
	if (val instanceof Compactable compactable) {
	setValueAt(i, compactable.unsafeOptimizeMemoryLayout());
	}
	}
	return internable ? interner.intern(this) : this;
	}

	/**
	* Returns true if this instance is internable (i.e. it contains only values that are considered
	* internable).
	*
	* <p>Internable instances are guaranteed to contain no object reference cycles, so they can be
	* interned by value equality.
	*/
	final boolean isInternable() {
	int n = provider.getFields().size();
	for (int i = 0; i < n; i++) {
	if (!valueIsInternable(getValueAt(i))) {
	return false;
	}
	}
	return true;
	}

	/**
	* A value is considered internable if its {@linkplain Starlark#truth truthiness} is false (except
	* for {@link StarlarkFloat} values, which are never internable), or it is an empty {@link
	* NestedSet}, or a {@code null}.
	*/
	private static boolean valueIsInternable(@Nullable Object val) {
	return switch (val) {
	case NestedSet<?> nestedSet -> nestedSet.isEmpty();
	// ``+0.0`, `-0.0`, and `0` are all `equals()` but have different memory representations.
	case StarlarkFloat sf -> false;
	case null -> true;
	default -> !Starlark.truth(val);
	};
	}

	/** Returns the index of the given named field in the given map of fields, or -1 if not found. */
	private static int indexOfField(String name, ImmutableMap<String, Integer> fields) {
	Integer idx = fields.get(name);
	return idx != null ? idx : -1;
	}

	/** For providers with no fields. */
	private static final class Schema0 extends StarlarkInfoWithSchema {
	Schema0(StarlarkProvider provider) {
	super(provider);
	}

	@Override
	Object getValueAt(int i) {
	throw new IndexOutOfBoundsException(i);
	}

	@Override
	void setValueAt(int i, Object val) {
	throw new IndexOutOfBoundsException(i);
	}

	@Override
	public int hashCode() {
	return 31 * getProvider().hashCode() + 1;
	}

	@Override
	public boolean equals(Object o) {
	if (this == o) {
	return true;
	}
	if (!(o instanceof Schema0 other)) {
	return false;
	}
	return getProvider().equals(other.getProvider());
	}
	}

	/** For providers with 1 field. */
	private static final class Schema1 extends StarlarkInfoWithSchema {
	private Object v0;

	Schema1(StarlarkProvider provider, Object v0) {
	super(provider);
	this.v0 = v0;
	}

	@Override
	Object getValueAt(int i) {
	if (i == 0) {
	return v0;
	}
	throw new IndexOutOfBoundsException(i);
	}

	@Override
	void setValueAt(int i, Object val) {
	if (i == 0) {
	this.v0 = val;
	return;
	}
	throw new IndexOutOfBoundsException(i);
	}

	@Override
	public int hashCode() {
	return HashCodes.hashObjects(getProvider(), v0);
	}

	@Override
	public boolean equals(Object o) {
	if (this == o) {
	return true;
	}
	if (!(o instanceof Schema1 other)) {
	return false;
	}
	return getProvider().equals(other.getProvider()) && Objects.equals(v0, other.v0);
	}
	}

	/** For providers with 2 fields. */
	private static final class Schema2 extends StarlarkInfoWithSchema {
	private Object v0;
	private Object v1;

	Schema2(StarlarkProvider provider, Object v0, Object v1) {
	super(provider);
	this.v0 = v0;
	this.v1 = v1;
	}

	@Override
	Object getValueAt(int i) {
	return switch (i) {
	case 0 -> v0;
	case 1 -> v1;
	default -> throw new IndexOutOfBoundsException(i);
	};
	}

	@Override
	void setValueAt(int i, Object val) {
	switch (i) {
	case 0 -> this.v0 = val;
	case 1 -> this.v1 = val;
	default -> throw new IndexOutOfBoundsException(i);
	}
	}

	@Override
	public int hashCode() {
	return HashCodes.hashObjects(getProvider(), v0, v1);
	}

	@Override
	public boolean equals(Object o) {
	if (this == o) {
	return true;
	}
	if (!(o instanceof Schema2 other)) {
	return false;
	}
	return getProvider().equals(other.getProvider())
	&& Objects.equals(v0, other.v0)
	&& Objects.equals(v1, other.v1);
	}
	}

	/** For providers with 3 fields. */
	private static final class Schema3 extends StarlarkInfoWithSchema {
	private Object v0;
	private Object v1;
	private Object v2;

	Schema3(StarlarkProvider provider, Object v0, Object v1, Object v2) {
	super(provider);
	this.v0 = v0;
	this.v1 = v1;
	this.v2 = v2;
	}

	@Override
	Object getValueAt(int i) {
	return switch (i) {
	case 0 -> v0;
	case 1 -> v1;
	case 2 -> v2;
	default -> throw new IndexOutOfBoundsException(i);
	};
	}

	@Override
	void setValueAt(int i, Object val) {
	switch (i) {
	case 0 -> this.v0 = val;
	case 1 -> this.v1 = val;
	case 2 -> this.v2 = val;
	default -> throw new IndexOutOfBoundsException(i);
	}
	}

	@Override
	public int hashCode() {
	return HashCodes.hashObjects(getProvider(), v0, v1, v2);
	}

	@Override
	public boolean equals(Object o) {
	if (this == o) {
	return true;
	}
	if (!(o instanceof Schema3 other)) {
	return false;
	}
	return getProvider().equals(other.getProvider())
	&& Objects.equals(v0, other.v0)
	&& Objects.equals(v1, other.v1)
	&& Objects.equals(v2, other.v2);
	}
	}

	/** For providers with 4 fields. */
	private static final class Schema4 extends StarlarkInfoWithSchema {
	private Object v0;
	private Object v1;
	private Object v2;
	private Object v3;

	Schema4(StarlarkProvider provider, Object v0, Object v1, Object v2, Object v3) {
	super(provider);
	this.v0 = v0;
	this.v1 = v1;
	this.v2 = v2;
	this.v3 = v3;
	}

	@Override
	Object getValueAt(int i) {
	return switch (i) {
	case 0 -> v0;
	case 1 -> v1;
	case 2 -> v2;
	case 3 -> v3;
	default -> throw new IndexOutOfBoundsException(i);
	};
	}

	@Override
	void setValueAt(int i, Object val) {
	switch (i) {
	case 0 -> this.v0 = val;
	case 1 -> this.v1 = val;
	case 2 -> this.v2 = val;
	case 3 -> this.v3 = val;
	default -> throw new IndexOutOfBoundsException(i);
	}
	}

	@Override
	public int hashCode() {
	return HashCodes.hashObjects(getProvider(), v0, v1, v2, v3);
	}

	@Override
	public boolean equals(Object o) {
	if (this == o) {
	return true;
	}
	if (!(o instanceof Schema4 other)) {
	return false;
	}
	return getProvider().equals(other.getProvider())
	&& Objects.equals(v0, other.v0)
	&& Objects.equals(v1, other.v1)
	&& Objects.equals(v2, other.v2)
	&& Objects.equals(v3, other.v3);
	}
	}

	/** For providers with 5 fields. */
	private static final class Schema5 extends StarlarkInfoWithSchema {
	private Object v0;
	private Object v1;
	private Object v2;
	private Object v3;
	private Object v4;

	Schema5(StarlarkProvider provider, Object v0, Object v1, Object v2, Object v3, Object v4) {
	super(provider);
	this.v0 = v0;
	this.v1 = v1;
	this.v2 = v2;
	this.v3 = v3;
	this.v4 = v4;
	}

	@Override
	Object getValueAt(int i) {
	return switch (i) {
	case 0 -> v0;
	case 1 -> v1;
	case 2 -> v2;
	case 3 -> v3;
	case 4 -> v4;
	default -> throw new IndexOutOfBoundsException(i);
	};
	}

	@Override
	void setValueAt(int i, Object val) {
	switch (i) {
	case 0 -> this.v0 = val;
	case 1 -> this.v1 = val;
	case 2 -> this.v2 = val;
	case 3 -> this.v3 = val;
	case 4 -> this.v4 = val;
	default -> throw new IndexOutOfBoundsException(i);
	}
	}

	@Override
	public int hashCode() {
	return HashCodes.hashObjects(getProvider(), v0, v1, v2, v3, v4);
	}

	@Override
	public boolean equals(Object o) {
	if (this == o) {
	return true;
	}
	if (!(o instanceof Schema5 other)) {
	return false;
	}
	return getProvider().equals(other.getProvider())
	&& Objects.equals(v0, other.v0)
	&& Objects.equals(v1, other.v1)
	&& Objects.equals(v2, other.v2)
	&& Objects.equals(v3, other.v3)
	&& Objects.equals(v4, other.v4);
	}
	}

	/** For providers with 6 or more fields. */
	private static final class SchemaN extends StarlarkInfoWithSchema {
	private final Object[] vs;

	SchemaN(StarlarkProvider provider, Object[] vs) {
	super(provider);
	this.vs = vs;
	}

	@Override
	Object getValueAt(int i) {
	return vs[i];
	}

	@Override
	void setValueAt(int i, Object val) {
	vs[i] = val;
	}

	@Override
	Object[] getValuesForSerialization() {
	return vs;
	}

	@Override
	public int hashCode() {
	return 31 * getProvider().hashCode() + Arrays.hashCode(vs);
	}

	@Override
	public boolean equals(Object o) {
	if (this == o) {
	return true;
	}
	if (!(o instanceof SchemaN other)) {
	return false;
	}
	return getProvider().equals(other.getProvider()) && Arrays.equals(vs, other.vs);
	}
	}
	}