src/main/java/com/google/devtools/build/lib/syntax/SkylarkDict.java - bazel - Git at Google

 // Copyright 2016 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.syntax;

 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.Lists;
 import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.skylarkinterface.Param;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkPrinter;
 import com.google.devtools.build.lib.syntax.SkylarkList.MutableList;
 import com.google.devtools.build.lib.syntax.SkylarkList.Tuple;
 import com.google.devtools.build.lib.syntax.SkylarkMutable.MutableMap;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import javax.annotation.Nullable;

 /**
  * A Skylark dictionary (dict).
  *
  * <p>Although this implements the {@link Map} interface, it is not mutable via that interface's
  * methods. Instead, use the mutators that take in a {@link Mutability} object.
  */
 @SkylarkModule(
   name = "dict",
   category = SkylarkModuleCategory.BUILTIN,
   doc =
       "A language built-in type representating a dictionary (associative mapping). "
           + "Dictionaries may be constructed with a special literal syntax:<br>"
           + "<pre class=\"language-python\">d = {\"a\": 2, \"b\": 5}</pre>"
           + "See also the <a href=\"globals.html#dict\">dict()</a> constructor function. "
           + "When using the literal syntax, it is an error to have duplicated keys. "
           + "Use square brackets to access elements:<br>"
           + "<pre class=\"language-python\">e = d[\"a\"]   # e == 2</pre>"
           + "Like lists, they can also be constructed using a comprehension syntax:<br>"
           + "<pre class=\"language-python\">d = {i: 2*i for i in range(20)}\n"
           + "e = d[8]       # e == 16</pre>"
           + "Dictionaries are mutable. You can add new elements or mutate existing ones:"
           + "<pre class=\"language-python\">d[\"key\"] = 5</pre>"
           + "<p>Iterating over a dict is equivalent to iterating over its keys. The "
           + "<code>in</code> operator tests for membership in the keyset of the dict.<br>"
           + "<pre class=\"language-python\">\"a\" in {\"a\" : 2, \"b\" : 5} "
           + "# evaluates as True</pre>"
           + "The iteration order for a dict is deterministic and specified as the order in which "
           + "the keys have been added to the dict. The iteration order is not affected if a value "
           + "associated with an existing key is updated."
 )
 public final class SkylarkDict<K, V> extends MutableMap<K, V>
     implements Map<K, V>, SkylarkIndexable {

   private final LinkedHashMap<K, V> contents = new LinkedHashMap<>();

   /** Final except for {@link #unsafeShallowFreeze}; must not be modified any other way. */
   private Mutability mutability;

   private SkylarkDict(@Nullable Mutability mutability) {
     this.mutability = mutability == null ? Mutability.IMMUTABLE : mutability;
   }

   private SkylarkDict(@Nullable Environment env) {
     this.mutability = env == null ? Mutability.IMMUTABLE : env.mutability();
   }

   @SkylarkCallable(name = "get",
     doc = "Returns the value for <code>key</code> if <code>key</code> is in the dictionary, "
         + "else <code>default</code>. If <code>default</code> is not given, it defaults to "
         + "<code>None</code>, so that this method never throws an error.",
     parameters = {
       @Param(name = "key", noneable = true, doc = "The key to look for."),
       @Param(name = "default", defaultValue = "None", noneable = true, named = true,
           doc = "The default value to use (instead of None) if the key is not found.")},
     allowReturnNones = true
   )
   public Object get(Object key, Object defaultValue) {
     if (this.containsKey(key)) {
       return this.get(key);
     }
     return defaultValue;
   }

   @SkylarkCallable(
       name = "pop",
       doc =
           "Removes a <code>key</code> from the dict, and returns the associated value. "
               + "If no entry with that key was found, remove nothing and return the specified "
               + "<code>default</code> value; if no default value was specified, fail instead.",
       parameters = {
         @Param(name = "key", type = Object.class, doc = "The key.", noneable = true),
         @Param(
             name = "default",
             type = Object.class,
             defaultValue = "unbound",
             named = true,
             noneable = true,
             doc = "a default value if the key is absent."),
       },
       useLocation = true,
       useEnvironment = true)
   public Object pop(Object key, Object defaultValue, Location loc, Environment env)
       throws EvalException {
     Object value = get(key);
     if (value != null) {
       remove(key, loc, env.mutability());
       return value;
     }
     if (defaultValue != Runtime.UNBOUND) {
       return defaultValue;
     }
     throw new EvalException(loc, Printer.format("KeyError: %r", key));
   }

   @SkylarkCallable(
       name = "popitem",
       doc =
           "Remove and return an arbitrary <code>(key, value)</code> pair from the dictionary. "
               + "<code>popitem()</code> is useful to destructively iterate over a dictionary, "
               + "as often used in set algorithms. "
               + "If the dictionary is empty, calling <code>popitem()</code> fails. "
               + "It is deterministic which pair is returned.",
       useLocation = true,
       useEnvironment = true
   )
   public Tuple<Object> popitem(Location loc, Environment env)
       throws EvalException {
     if (isEmpty()) {
       throw new EvalException(loc, "popitem(): dictionary is empty");
     }
     Object key = keySet().iterator().next();
     Object value = get(key);
     remove(key, loc, env.mutability());
     return Tuple.of(key, value);
   }

   @SkylarkCallable(
     name = "setdefault",
     doc =
         "If <code>key</code> is in the dictionary, return its value. "
             + "If not, insert key with a value of <code>default</code> "
             + "and return <code>default</code>. "
             + "<code>default</code> defaults to <code>None</code>.",
     parameters = {
         @Param(name = "key", type = Object.class, doc = "The key."),
         @Param(
             name = "default",
             type = Object.class,
             defaultValue = "None",
             named = true,
             noneable = true,
             doc = "a default value if the key is absent."
         ),
     },
     useLocation = true,
     useEnvironment = true
   )
   public Object setdefault(
       K key,
       V defaultValue,
       Location loc,
       Environment env)
       throws EvalException {
     Object value = get(key);
     if (value != null) {
       return value;
     }
     put(key, defaultValue, loc, env);
     return defaultValue;
   }

   @SkylarkCallable(
     name = "update",
     doc = "Update the dictionary with the key/value pairs from other, overwriting existing keys.",
     parameters = {
         @Param(name = "other", type = SkylarkDict.class, doc = "The values to add."),
     },
     useLocation = true,
     useEnvironment = true
   )
   public Runtime.NoneType update(
       SkylarkDict<K, V> other,
       Location loc,
       Environment env)
       throws EvalException {
     putAll(other, loc, env.mutability());
     return Runtime.NONE;
   }

   @SkylarkCallable(
     name = "values",
     doc =
         "Returns the list of values:"
             + "<pre class=\"language-python\">"
             + "{2: \"a\", 4: \"b\", 1: \"c\"}.values() == [\"a\", \"b\", \"c\"]</pre>\n",
     useEnvironment = true
   )
   public MutableList<?> invoke(Environment env) throws EvalException {
     return MutableList.copyOf(env, values());
   }

   @SkylarkCallable(
     name = "items",
     doc =
         "Returns the list of key-value tuples:"
             + "<pre class=\"language-python\">"
             + "{2: \"a\", 4: \"b\", 1: \"c\"}.items() == [(2, \"a\"), (4, \"b\"), (1, \"c\")]"
             + "</pre>\n",
     useEnvironment = true
   )
   public MutableList<?> items(Environment env) throws EvalException {
     ArrayList<Object> list = Lists.newArrayListWithCapacity(size());
     for (Map.Entry<?, ?> entries : entrySet()) {
       list.add(Tuple.of(entries.getKey(), entries.getValue()));
     }
     return MutableList.wrapUnsafe(env, list);
   }

   @SkylarkCallable(name = "keys",
     doc = "Returns the list of keys:"
         + "<pre class=\"language-python\">{2: \"a\", 4: \"b\", 1: \"c\"}.keys() == [2, 4, 1]"
         + "</pre>\n",
     useEnvironment = true
   )
   public MutableList<?> keys(Environment env) throws EvalException {
     ArrayList<Object> list = Lists.newArrayListWithCapacity(size());
     for (Map.Entry<?, ?> entries : entrySet()) {
       list.add(entries.getKey());
     }
     return MutableList.wrapUnsafe(env, list);
   }

   private static final SkylarkDict<?, ?> EMPTY = withMutability(Mutability.IMMUTABLE);

   /** Returns an immutable empty dict. */
   // Safe because the empty singleton is immutable.
   @SuppressWarnings("unchecked")
   public static <K, V> SkylarkDict<K, V> empty() {
     return (SkylarkDict<K, V>) EMPTY;
   }

   /** Returns an empty dict with the given {@link Mutability}. */
   public static <K, V> SkylarkDict<K, V> withMutability(@Nullable Mutability mutability) {
     return new SkylarkDict<>(mutability);
   }

   /** @return a dict mutable in given environment only */
   public static <K, V> SkylarkDict<K, V> of(@Nullable Environment env) {
     return new SkylarkDict<>(env);
   }

   /** @return a dict mutable in given environment only, with given initial key and value */
   public static <K, V> SkylarkDict<K, V> of(@Nullable Environment env, K k, V v) {
     return SkylarkDict.<K, V>of(env).putUnsafe(k, v);
   }

   /** @return a dict mutable in given environment only, with two given initial key value pairs */
   public static <K, V> SkylarkDict<K, V> of(
       @Nullable Environment env, K k1, V v1, K k2, V v2) {
     return SkylarkDict.<K, V>of(env).putUnsafe(k1, v1).putUnsafe(k2, v2);
   }

   // TODO(bazel-team): Make other methods that take in mutabilities instead of environments, make
   // this method public.
   @VisibleForTesting
   static <K, V> SkylarkDict<K, V> copyOf(
       @Nullable Mutability mutability, Map<? extends K, ? extends V> m) {
     return SkylarkDict.<K, V>withMutability(mutability).putAllUnsafe(m);
   }

   /** @return a dict mutable in given environment only, with contents copied from given map */
   public static <K, V> SkylarkDict<K, V> copyOf(
       @Nullable Environment env, Map<? extends K, ? extends V> m) {
     return SkylarkDict.<K, V>of(env).putAllUnsafe(m);
   }

   /** Puts the given entry into the dict, without calling {@link #checkMutable}. */
   private SkylarkDict<K, V> putUnsafe(K k, V v) {
     contents.put(k, v);
     return this;
   }

   /** Puts all entries of the given map into the dict, without calling {@link #checkMutable}. */
   @SuppressWarnings("unchecked")
   private <KK extends K, VV extends V> SkylarkDict<K, V> putAllUnsafe(Map<KK, VV> m) {
     for (Map.Entry<KK, VV> e : m.entrySet()) {
       contents.put(e.getKey(), (VV) SkylarkType.convertToSkylark(e.getValue(), mutability));
     }
     return this;
   }

   @Override
   public Mutability mutability() {
     return mutability;
   }

   @Override
   public void unsafeShallowFreeze() {
     Mutability.Freezable.checkUnsafeShallowFreezePrecondition(this);
     this.mutability = Mutability.IMMUTABLE;
   }

   @Override
   protected Map<K, V> getContentsUnsafe() {
     return contents;
   }

   /**
    * Puts an entry into a dict, after validating that mutation is allowed.
    *
    * @param key the key of the added entry
    * @param value the value of the added entry
    * @param loc the location to use for error reporting
    * @param mutability the {@link Mutability} associated with the opreation
    * @throws EvalException if the key is invalid or the dict is frozen
    */
   public void put(K key, V value, Location loc, Mutability mutability) throws EvalException {
     checkMutable(loc, mutability);
     EvalUtils.checkValidDictKey(key);
     contents.put(key, value);
   }

   /**
    * Convenience version of {@link #put(K, V, Location, Mutability)} that uses the {@link
    * Mutability} of an {@link Environment}.
    */
   // TODO(bazel-team): Decide whether to eliminate this overload.
   public void put(K key, V value, Location loc, Environment env) throws EvalException {
     put(key, value, loc, env.mutability());
   }

   /**
    * Puts all the entries from a given map into the dict, after validating that mutation is allowed.
    *
    * @param map the map whose entries are added
    * @param loc the location to use for error reporting
    * @param mutability the {@link Mutability} associated with the operation
    * @throws EvalException if some key is invalid or the dict is frozen
    */
   public <KK extends K, VV extends V> void putAll(
       Map<KK, VV> map, Location loc, Mutability mutability) throws EvalException {
     checkMutable(loc, mutability);
     for (Map.Entry<KK, VV> e : map.entrySet()) {
       KK k = e.getKey();
       EvalUtils.checkValidDictKey(k);
       contents.put(k, e.getValue());
     }
   }

   /**
    * Deletes the entry associated with the given key.
    *
    * @param key the key to delete
    * @param loc the location to use for error reporting
    * @param mutability the {@link Mutability} associated with the operation
    * @return the value associated to the key, or {@code null} if not present
    * @throws EvalException if the dict is frozen
    */
   V remove(Object key, Location loc, Mutability mutability) throws EvalException {
     checkMutable(loc, mutability);
     return contents.remove(key);
   }

   @SkylarkCallable(
       name = "clear",
       doc = "Remove all items from the dictionary.",
       useLocation = true,
       useEnvironment = true
   )
   public Runtime.NoneType clearDict(
       Location loc, Environment env)
       throws EvalException {
     clear(loc, env.mutability());
     return Runtime.NONE;
   }

   /**
    * Clears the dict.
    *
    * @param loc the location to use for error reporting
    * @param mutability the {@link Mutability} associated with the operation
    * @throws EvalException if the dict is frozen
    */
   void clear(Location loc, Mutability mutability) throws EvalException {
     checkMutable(loc, mutability);
     contents.clear();
   }

   @Override
   public void repr(SkylarkPrinter printer) {
     printer.printList(entrySet(), "{", ", ", "}", null);
   }

   @Override
   public String toString() {
     return Printer.repr(this);
   }

   /**
    * If {@code obj} is a {@code SkylarkDict}, casts it to an unmodifiable {@code Map<K, V>} after
    * checking that each of its entries has key type {@code keyType} and value type {@code
    * valueType}. If {@code obj} is {@code None} or null, treats it as an empty dict.
    *
    * <p>The returned map may or may not be a view that is affected by updates to the original dict.
    *
    * @param obj the object to cast. null and None are treated as an empty dict.
    * @param keyType the expected type of all the dict's keys
    * @param valueType the expected type of all the dict's values
    * @param description a description of the argument being converted, or null, for debugging
    */
   public static <K, V> Map<K, V> castSkylarkDictOrNoneToDict(
       Object obj, Class<K> keyType, Class<V> valueType, @Nullable String description)
       throws EvalException {
     if (EvalUtils.isNullOrNone(obj)) {
       return empty();
     }
     if (obj instanceof SkylarkDict) {
       return ((SkylarkDict<?, ?>) obj).getContents(keyType, valueType, description);
     }
     throw new EvalException(
         null,
         String.format(
             "%s is not of expected type dict or NoneType",
             description == null ? Printer.repr(obj) : String.format("'%s'", description)));
   }

   /**
    * Casts this dict to an unmodifiable {@code SkylarkDict<X, Y>}, after checking that all keys and
    * values have types {@code keyType} and {@code valueType} respectively.
    *
    * <p>The returned map may or may not be a view that is affected by updates to the original dict.
    *
    * @param keyType the expected class of keys
    * @param valueType the expected class of values
    * @param description a description of the argument being converted, or null, for debugging
    */
   @SuppressWarnings("unchecked")
   public <X, Y> Map<X, Y> getContents(
       Class<X> keyType, Class<Y> valueType, @Nullable String description)
       throws EvalException {
     Object keyDescription = description == null
         ? null : Printer.formattable("'%s' key", description);
     Object valueDescription = description == null
         ? null : Printer.formattable("'%s' value", description);
     for (Map.Entry<?, ?> e : this.entrySet()) {
       SkylarkType.checkType(e.getKey(), keyType, keyDescription);
       if (e.getValue() != null) {
         SkylarkType.checkType(e.getValue(), valueType, valueDescription);
       }
     }
     return Collections.unmodifiableMap((SkylarkDict<X, Y>) this);
   }

   @Override
   public final Object getIndex(Object key, Location loc) throws EvalException {
     if (!this.containsKey(key)) {
       throw new EvalException(loc, Printer.format("key %r not found in dictionary", key));
     }
     return this.get(key);
   }

   @Override
   public final boolean containsKey(Object key, Location loc) throws EvalException {
     return this.containsKey(key);
   }

   public static <K, V> SkylarkDict<K, V> plus(
       SkylarkDict<? extends K, ? extends V> left,
       SkylarkDict<? extends K, ? extends V> right,
       @Nullable Environment env) {
     SkylarkDict<K, V> result = SkylarkDict.of(env);
     result.putAllUnsafe(left);
     result.putAllUnsafe(right);
     return result;
   }
 }
	// Copyright 2016 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.syntax;

	import com.google.common.annotations.VisibleForTesting;
	import com.google.common.collect.Lists;
	import com.google.devtools.build.lib.events.Location;
	import com.google.devtools.build.lib.skylarkinterface.Param;
	import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
	import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
	import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
	import com.google.devtools.build.lib.skylarkinterface.SkylarkPrinter;
	import com.google.devtools.build.lib.syntax.SkylarkList.MutableList;
	import com.google.devtools.build.lib.syntax.SkylarkList.Tuple;
	import com.google.devtools.build.lib.syntax.SkylarkMutable.MutableMap;
	import java.util.ArrayList;
	import java.util.Collections;
	import java.util.LinkedHashMap;
	import java.util.Map;
	import javax.annotation.Nullable;

	/**
	* A Skylark dictionary (dict).
	*
	* <p>Although this implements the {@link Map} interface, it is not mutable via that interface's
	* methods. Instead, use the mutators that take in a {@link Mutability} object.
	*/
	@SkylarkModule(
	name = "dict",
	category = SkylarkModuleCategory.BUILTIN,
	doc =
	"A language built-in type representating a dictionary (associative mapping). "
	+ "Dictionaries may be constructed with a special literal syntax:<br>"
	+ "<pre class=\"language-python\">d = {\"a\": 2, \"b\": 5}</pre>"
	+ "See also the <a href=\"globals.html#dict\">dict()</a> constructor function. "
	+ "When using the literal syntax, it is an error to have duplicated keys. "
	+ "Use square brackets to access elements:<br>"
	+ "<pre class=\"language-python\">e = d[\"a\"] # e == 2</pre>"
	+ "Like lists, they can also be constructed using a comprehension syntax:<br>"
	+ "<pre class=\"language-python\">d = {i: 2*i for i in range(20)}\n"
	+ "e = d[8] # e == 16</pre>"
	+ "Dictionaries are mutable. You can add new elements or mutate existing ones:"
	+ "<pre class=\"language-python\">d[\"key\"] = 5</pre>"
	+ "<p>Iterating over a dict is equivalent to iterating over its keys. The "
	+ "<code>in</code> operator tests for membership in the keyset of the dict.<br>"
	+ "<pre class=\"language-python\">\"a\" in {\"a\" : 2, \"b\" : 5} "
	+ "# evaluates as True</pre>"
	+ "The iteration order for a dict is deterministic and specified as the order in which "
	+ "the keys have been added to the dict. The iteration order is not affected if a value "
	+ "associated with an existing key is updated."
	)
	public final class SkylarkDict<K, V> extends MutableMap<K, V>
	implements Map<K, V>, SkylarkIndexable {

	private final LinkedHashMap<K, V> contents = new LinkedHashMap<>();

	/** Final except for {@link #unsafeShallowFreeze}; must not be modified any other way. */
	private Mutability mutability;

	private SkylarkDict(@Nullable Mutability mutability) {
	this.mutability = mutability == null ? Mutability.IMMUTABLE : mutability;
	}

	private SkylarkDict(@Nullable Environment env) {
	this.mutability = env == null ? Mutability.IMMUTABLE : env.mutability();
	}

	@SkylarkCallable(name = "get",
	doc = "Returns the value for <code>key</code> if <code>key</code> is in the dictionary, "
	+ "else <code>default</code>. If <code>default</code> is not given, it defaults to "
	+ "<code>None</code>, so that this method never throws an error.",
	parameters = {
	@Param(name = "key", noneable = true, doc = "The key to look for."),
	@Param(name = "default", defaultValue = "None", noneable = true, named = true,
	doc = "The default value to use (instead of None) if the key is not found.")},
	allowReturnNones = true
	)
	public Object get(Object key, Object defaultValue) {
	if (this.containsKey(key)) {
	return this.get(key);
	}
	return defaultValue;
	}

	@SkylarkCallable(
	name = "pop",
	doc =
	"Removes a <code>key</code> from the dict, and returns the associated value. "
	+ "If no entry with that key was found, remove nothing and return the specified "
	+ "<code>default</code> value; if no default value was specified, fail instead.",
	parameters = {
	@Param(name = "key", type = Object.class, doc = "The key.", noneable = true),
	@Param(
	name = "default",
	type = Object.class,
	defaultValue = "unbound",
	named = true,
	noneable = true,
	doc = "a default value if the key is absent."),
	},
	useLocation = true,
	useEnvironment = true)
	public Object pop(Object key, Object defaultValue, Location loc, Environment env)
	throws EvalException {
	Object value = get(key);
	if (value != null) {
	remove(key, loc, env.mutability());
	return value;
	}
	if (defaultValue != Runtime.UNBOUND) {
	return defaultValue;
	}
	throw new EvalException(loc, Printer.format("KeyError: %r", key));
	}

	@SkylarkCallable(
	name = "popitem",
	doc =
	"Remove and return an arbitrary <code>(key, value)</code> pair from the dictionary. "
	+ "<code>popitem()</code> is useful to destructively iterate over a dictionary, "
	+ "as often used in set algorithms. "
	+ "If the dictionary is empty, calling <code>popitem()</code> fails. "
	+ "It is deterministic which pair is returned.",
	useLocation = true,
	useEnvironment = true
	)
	public Tuple<Object> popitem(Location loc, Environment env)
	throws EvalException {
	if (isEmpty()) {
	throw new EvalException(loc, "popitem(): dictionary is empty");
	}
	Object key = keySet().iterator().next();
	Object value = get(key);
	remove(key, loc, env.mutability());
	return Tuple.of(key, value);
	}

	@SkylarkCallable(
	name = "setdefault",
	doc =
	"If <code>key</code> is in the dictionary, return its value. "
	+ "If not, insert key with a value of <code>default</code> "
	+ "and return <code>default</code>. "
	+ "<code>default</code> defaults to <code>None</code>.",
	parameters = {
	@Param(name = "key", type = Object.class, doc = "The key."),
	@Param(
	name = "default",
	type = Object.class,
	defaultValue = "None",
	named = true,
	noneable = true,
	doc = "a default value if the key is absent."
	),
	},
	useLocation = true,
	useEnvironment = true
	)
	public Object setdefault(
	K key,
	V defaultValue,
	Location loc,
	Environment env)
	throws EvalException {
	Object value = get(key);
	if (value != null) {
	return value;
	}
	put(key, defaultValue, loc, env);
	return defaultValue;
	}

	@SkylarkCallable(
	name = "update",
	doc = "Update the dictionary with the key/value pairs from other, overwriting existing keys.",
	parameters = {
	@Param(name = "other", type = SkylarkDict.class, doc = "The values to add."),
	},
	useLocation = true,
	useEnvironment = true
	)
	public Runtime.NoneType update(
	SkylarkDict<K, V> other,
	Location loc,
	Environment env)
	throws EvalException {
	putAll(other, loc, env.mutability());
	return Runtime.NONE;
	}

	@SkylarkCallable(
	name = "values",
	doc =
	"Returns the list of values:"
	+ "<pre class=\"language-python\">"
	+ "{2: \"a\", 4: \"b\", 1: \"c\"}.values() == [\"a\", \"b\", \"c\"]</pre>\n",
	useEnvironment = true
	)
	public MutableList<?> invoke(Environment env) throws EvalException {
	return MutableList.copyOf(env, values());
	}

	@SkylarkCallable(
	name = "items",
	doc =
	"Returns the list of key-value tuples:"
	+ "<pre class=\"language-python\">"
	+ "{2: \"a\", 4: \"b\", 1: \"c\"}.items() == [(2, \"a\"), (4, \"b\"), (1, \"c\")]"
	+ "</pre>\n",
	useEnvironment = true
	)
	public MutableList<?> items(Environment env) throws EvalException {
	ArrayList<Object> list = Lists.newArrayListWithCapacity(size());
	for (Map.Entry<?, ?> entries : entrySet()) {
	list.add(Tuple.of(entries.getKey(), entries.getValue()));
	}
	return MutableList.wrapUnsafe(env, list);
	}

	@SkylarkCallable(name = "keys",
	doc = "Returns the list of keys:"
	+ "<pre class=\"language-python\">{2: \"a\", 4: \"b\", 1: \"c\"}.keys() == [2, 4, 1]"
	+ "</pre>\n",
	useEnvironment = true
	)
	public MutableList<?> keys(Environment env) throws EvalException {
	ArrayList<Object> list = Lists.newArrayListWithCapacity(size());
	for (Map.Entry<?, ?> entries : entrySet()) {
	list.add(entries.getKey());
	}
	return MutableList.wrapUnsafe(env, list);
	}

	private static final SkylarkDict<?, ?> EMPTY = withMutability(Mutability.IMMUTABLE);

	/** Returns an immutable empty dict. */
	// Safe because the empty singleton is immutable.
	@SuppressWarnings("unchecked")
	public static <K, V> SkylarkDict<K, V> empty() {
	return (SkylarkDict<K, V>) EMPTY;
	}

	/** Returns an empty dict with the given {@link Mutability}. */
	public static <K, V> SkylarkDict<K, V> withMutability(@Nullable Mutability mutability) {
	return new SkylarkDict<>(mutability);
	}

	/** @return a dict mutable in given environment only */
	public static <K, V> SkylarkDict<K, V> of(@Nullable Environment env) {
	return new SkylarkDict<>(env);
	}

	/** @return a dict mutable in given environment only, with given initial key and value */
	public static <K, V> SkylarkDict<K, V> of(@Nullable Environment env, K k, V v) {
	return SkylarkDict.<K, V>of(env).putUnsafe(k, v);
	}

	/** @return a dict mutable in given environment only, with two given initial key value pairs */
	public static <K, V> SkylarkDict<K, V> of(
	@Nullable Environment env, K k1, V v1, K k2, V v2) {
	return SkylarkDict.<K, V>of(env).putUnsafe(k1, v1).putUnsafe(k2, v2);
	}

	// TODO(bazel-team): Make other methods that take in mutabilities instead of environments, make
	// this method public.
	@VisibleForTesting
	static <K, V> SkylarkDict<K, V> copyOf(
	@Nullable Mutability mutability, Map<? extends K, ? extends V> m) {
	return SkylarkDict.<K, V>withMutability(mutability).putAllUnsafe(m);
	}

	/** @return a dict mutable in given environment only, with contents copied from given map */
	public static <K, V> SkylarkDict<K, V> copyOf(
	@Nullable Environment env, Map<? extends K, ? extends V> m) {
	return SkylarkDict.<K, V>of(env).putAllUnsafe(m);
	}

	/** Puts the given entry into the dict, without calling {@link #checkMutable}. */
	private SkylarkDict<K, V> putUnsafe(K k, V v) {
	contents.put(k, v);
	return this;
	}

	/** Puts all entries of the given map into the dict, without calling {@link #checkMutable}. */
	@SuppressWarnings("unchecked")
	private <KK extends K, VV extends V> SkylarkDict<K, V> putAllUnsafe(Map<KK, VV> m) {
	for (Map.Entry<KK, VV> e : m.entrySet()) {
	contents.put(e.getKey(), (VV) SkylarkType.convertToSkylark(e.getValue(), mutability));
	}
	return this;
	}

	@Override
	public Mutability mutability() {
	return mutability;
	}

	@Override
	public void unsafeShallowFreeze() {
	Mutability.Freezable.checkUnsafeShallowFreezePrecondition(this);
	this.mutability = Mutability.IMMUTABLE;
	}

	@Override
	protected Map<K, V> getContentsUnsafe() {
	return contents;
	}

	/**
	* Puts an entry into a dict, after validating that mutation is allowed.
	*
	* @param key the key of the added entry
	* @param value the value of the added entry
	* @param loc the location to use for error reporting
	* @param mutability the {@link Mutability} associated with the opreation
	* @throws EvalException if the key is invalid or the dict is frozen
	*/
	public void put(K key, V value, Location loc, Mutability mutability) throws EvalException {
	checkMutable(loc, mutability);
	EvalUtils.checkValidDictKey(key);
	contents.put(key, value);
	}

	/**
	* Convenience version of {@link #put(K, V, Location, Mutability)} that uses the {@link
	* Mutability} of an {@link Environment}.
	*/
	// TODO(bazel-team): Decide whether to eliminate this overload.
	public void put(K key, V value, Location loc, Environment env) throws EvalException {
	put(key, value, loc, env.mutability());
	}

	/**
	* Puts all the entries from a given map into the dict, after validating that mutation is allowed.
	*
	* @param map the map whose entries are added
	* @param loc the location to use for error reporting
	* @param mutability the {@link Mutability} associated with the operation
	* @throws EvalException if some key is invalid or the dict is frozen
	*/
	public <KK extends K, VV extends V> void putAll(
	Map<KK, VV> map, Location loc, Mutability mutability) throws EvalException {
	checkMutable(loc, mutability);
	for (Map.Entry<KK, VV> e : map.entrySet()) {
	KK k = e.getKey();
	EvalUtils.checkValidDictKey(k);
	contents.put(k, e.getValue());
	}
	}

	/**
	* Deletes the entry associated with the given key.
	*
	* @param key the key to delete
	* @param loc the location to use for error reporting
	* @param mutability the {@link Mutability} associated with the operation
	* @return the value associated to the key, or {@code null} if not present
	* @throws EvalException if the dict is frozen
	*/
	V remove(Object key, Location loc, Mutability mutability) throws EvalException {
	checkMutable(loc, mutability);
	return contents.remove(key);
	}

	@SkylarkCallable(
	name = "clear",
	doc = "Remove all items from the dictionary.",
	useLocation = true,
	useEnvironment = true
	)
	public Runtime.NoneType clearDict(
	Location loc, Environment env)
	throws EvalException {
	clear(loc, env.mutability());
	return Runtime.NONE;
	}

	/**
	* Clears the dict.
	*
	* @param loc the location to use for error reporting
	* @param mutability the {@link Mutability} associated with the operation
	* @throws EvalException if the dict is frozen
	*/
	void clear(Location loc, Mutability mutability) throws EvalException {
	checkMutable(loc, mutability);
	contents.clear();
	}

	@Override
	public void repr(SkylarkPrinter printer) {
	printer.printList(entrySet(), "{", ", ", "}", null);
	}

	@Override
	public String toString() {
	return Printer.repr(this);
	}

	/**
	* If {@code obj} is a {@code SkylarkDict}, casts it to an unmodifiable {@code Map<K, V>} after
	* checking that each of its entries has key type {@code keyType} and value type {@code
	* valueType}. If {@code obj} is {@code None} or null, treats it as an empty dict.
	*
	* <p>The returned map may or may not be a view that is affected by updates to the original dict.
	*
	* @param obj the object to cast. null and None are treated as an empty dict.
	* @param keyType the expected type of all the dict's keys
	* @param valueType the expected type of all the dict's values
	* @param description a description of the argument being converted, or null, for debugging
	*/
	public static <K, V> Map<K, V> castSkylarkDictOrNoneToDict(
	Object obj, Class<K> keyType, Class<V> valueType, @Nullable String description)
	throws EvalException {
	if (EvalUtils.isNullOrNone(obj)) {
	return empty();
	}
	if (obj instanceof SkylarkDict) {
	return ((SkylarkDict<?, ?>) obj).getContents(keyType, valueType, description);
	}
	throw new EvalException(
	null,
	String.format(
	"%s is not of expected type dict or NoneType",
	description == null ? Printer.repr(obj) : String.format("'%s'", description)));
	}

	/**
	* Casts this dict to an unmodifiable {@code SkylarkDict<X, Y>}, after checking that all keys and
	* values have types {@code keyType} and {@code valueType} respectively.
	*
	* <p>The returned map may or may not be a view that is affected by updates to the original dict.
	*
	* @param keyType the expected class of keys
	* @param valueType the expected class of values
	* @param description a description of the argument being converted, or null, for debugging
	*/
	@SuppressWarnings("unchecked")
	public <X, Y> Map<X, Y> getContents(
	Class<X> keyType, Class<Y> valueType, @Nullable String description)
	throws EvalException {
	Object keyDescription = description == null
	? null : Printer.formattable("'%s' key", description);
	Object valueDescription = description == null
	? null : Printer.formattable("'%s' value", description);
	for (Map.Entry<?, ?> e : this.entrySet()) {
	SkylarkType.checkType(e.getKey(), keyType, keyDescription);
	if (e.getValue() != null) {
	SkylarkType.checkType(e.getValue(), valueType, valueDescription);
	}
	}
	return Collections.unmodifiableMap((SkylarkDict<X, Y>) this);
	}

	@Override
	public final Object getIndex(Object key, Location loc) throws EvalException {
	if (!this.containsKey(key)) {
	throw new EvalException(loc, Printer.format("key %r not found in dictionary", key));
	}
	return this.get(key);
	}

	@Override
	public final boolean containsKey(Object key, Location loc) throws EvalException {
	return this.containsKey(key);
	}

	public static <K, V> SkylarkDict<K, V> plus(
	SkylarkDict<? extends K, ? extends V> left,
	SkylarkDict<? extends K, ? extends V> right,
	@Nullable Environment env) {
	SkylarkDict<K, V> result = SkylarkDict.of(env);
	result.putAllUnsafe(left);
	result.putAllUnsafe(right);
	return result;
	}
	}