1 files changed, 837 insertions, 0 deletions
diff --git a/Firestore/Source/Model/FSTFieldValue.m b/Firestore/Source/Model/FSTFieldValue.m
new file mode 100644
index 0000000..7f96a3c
--- /dev/null
+++ b/Firestore/Source/Model/FSTFieldValue.m
@@ -0,0 +1,837 @@
+/*
+ * Copyright 2017 Google
+ *
+ * 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.
+ */
+
+#import "FSTFieldValue.h"
+
+#import "FIRGeoPoint+Internal.h"
+#import "FSTAssert.h"
+#import "FSTClasses.h"
+#import "FSTComparison.h"
+#import "FSTDatabaseID.h"
+#import "FSTDocumentKey.h"
+#import "FSTPath.h"
+#import "FSTTimestamp.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+#pragma mark - FSTFieldValue
+
+@interface FSTFieldValue ()
+- (NSComparisonResult)defaultCompare:(FSTFieldValue *)other;
+@end
+
+@implementation FSTFieldValue
+
+- (FSTTypeOrder)typeOrder {
+  @throw FSTAbstractMethodException();  // NOLINT
+}
+
+- (id)value {
+  @throw FSTAbstractMethodException();  // NOLINT
+}
+
+- (BOOL)isEqual:(id)other {
+  @throw FSTAbstractMethodException();  // NOLINT
+}
+
+- (NSUInteger)hash {
+  @throw FSTAbstractMethodException();  // NOLINT
+}
+
+- (NSComparisonResult)compare:(FSTFieldValue *)other {
+  @throw FSTAbstractMethodException();  // NOLINT
+}
+
+- (NSString *)description {
+  return [[self value] description];
+}
+
+- (NSComparisonResult)defaultCompare:(FSTFieldValue *)other {
+  if (self.typeOrder > other.typeOrder) {
+    return NSOrderedDescending;
+  } else {
+    FSTAssert(self.typeOrder < other.typeOrder,
+              @"defaultCompare should not be used for values of same type.");
+    return NSOrderedAscending;
+  }
+}
+
+@end
+
+#pragma mark - FSTNullValue
+
+@implementation FSTNullValue
+
++ (instancetype)nullValue {
+  static FSTNullValue *sharedInstance = nil;
+  static dispatch_once_t onceToken;
+
+  dispatch_once(&onceToken, ^{
+    sharedInstance = [[FSTNullValue alloc] init];
+  });
+  return sharedInstance;
+}
+
+- (FSTTypeOrder)typeOrder {
+  return FSTTypeOrderNull;
+}
+
+- (id)value {
+  return [NSNull null];
+}
+
+- (BOOL)isEqual:(id)other {
+  return [other isKindOfClass:[self class]];
+}
+
+- (NSUInteger)hash {
+  return 47;
+}
+
+- (NSComparisonResult)compare:(FSTFieldValue *)other {
+  if ([other isKindOfClass:[self class]]) {
+    return NSOrderedSame;
+  } else {
+    return [self defaultCompare:other];
+  }
+}
+
+@end
+
+#pragma mark - FSTBooleanValue
+
+@interface FSTBooleanValue ()
+@property(nonatomic, assign, readonly) BOOL internalValue;
+@end
+
+@implementation FSTBooleanValue
+
++ (instancetype)trueValue {
+  static FSTBooleanValue *sharedInstance = nil;
+  static dispatch_once_t onceToken;
+
+  dispatch_once(&onceToken, ^{
+    sharedInstance = [[FSTBooleanValue alloc] initWithValue:YES];
+  });
+  return sharedInstance;
+}
+
++ (instancetype)falseValue {
+  static FSTBooleanValue *sharedInstance = nil;
+  static dispatch_once_t onceToken;
+
+  dispatch_once(&onceToken, ^{
+    sharedInstance = [[FSTBooleanValue alloc] initWithValue:NO];
+  });
+  return sharedInstance;
+}
+
++ (instancetype)booleanValue:(BOOL)value {
+  return value ? [FSTBooleanValue trueValue] : [FSTBooleanValue falseValue];
+}
+
+- (id)initWithValue:(BOOL)value {
+  self = [super init];
+  if (self) {
+    _internalValue = value;
+  }
+  return self;
+}
+
+- (FSTTypeOrder)typeOrder {
+  return FSTTypeOrderBoolean;
+}
+
+- (id)value {
+  return self.internalValue ? @YES : @NO;
+}
+
+- (BOOL)isEqual:(id)other {
+  // Since we create shared instances for true / false, we can use reference equality.
+  return self == other;
+}
+
+- (NSUInteger)hash {
+  return self.internalValue ? 1231 : 1237;
+}
+
+- (NSComparisonResult)compare:(FSTFieldValue *)other {
+  if ([other isKindOfClass:[FSTBooleanValue class]]) {
+    return FSTCompareBools(self.internalValue, ((FSTBooleanValue *)other).internalValue);
+  } else {
+    return [self defaultCompare:other];
+  }
+}
+
+@end
+
+#pragma mark - FSTNumberValue
+
+@implementation FSTNumberValue
+
+- (FSTTypeOrder)typeOrder {
+  return FSTTypeOrderNumber;
+}
+
+- (NSComparisonResult)compare:(FSTFieldValue *)other {
+  if (![other isKindOfClass:[FSTNumberValue class]]) {
+    return [self defaultCompare:other];
+  } else {
+    if ([self isKindOfClass:[FSTDoubleValue class]]) {
+      double thisDouble = ((FSTDoubleValue *)self).internalValue;
+      if ([other isKindOfClass:[FSTDoubleValue class]]) {
+        return FSTCompareDoubles(thisDouble, ((FSTDoubleValue *)other).internalValue);
+      } else {
+        FSTAssert([other isKindOfClass:[FSTIntegerValue class]], @"Unknown number value: %@",
+                  other);
+        return FSTCompareMixed(thisDouble, ((FSTIntegerValue *)other).internalValue);
+      }
+    } else {
+      int64_t thisInt = ((FSTIntegerValue *)self).internalValue;
+      if ([other isKindOfClass:[FSTIntegerValue class]]) {
+        return FSTCompareInt64s(thisInt, ((FSTIntegerValue *)other).internalValue);
+      } else {
+        FSTAssert([other isKindOfClass:[FSTDoubleValue class]], @"Unknown number value: %@", other);
+        return -1 * FSTCompareMixed(((FSTDoubleValue *)other).internalValue, thisInt);
+      }
+    }
+  }
+}
+
+@end
+
+#pragma mark - FSTIntegerValue
+
+@interface FSTIntegerValue ()
+@property(nonatomic, assign, readonly) int64_t internalValue;
+@end
+
+@implementation FSTIntegerValue
+
++ (instancetype)integerValue:(int64_t)value {
+  return [[FSTIntegerValue alloc] initWithValue:value];
+}
+
+- (id)initWithValue:(int64_t)value {
+  self = [super init];
+  if (self) {
+    _internalValue = value;
+  }
+  return self;
+}
+
+- (id)value {
+  return @(self.internalValue);
+}
+
+- (BOOL)isEqual:(id)other {
+  // NOTE: DoubleValue and LongValue instances may compare: the same, but that doesn't make them
+  // equal via isEqual:
+  return [other isKindOfClass:[FSTIntegerValue class]] &&
+         self.internalValue == ((FSTIntegerValue *)other).internalValue;
+}
+
+- (NSUInteger)hash {
+  return (((NSUInteger)self.internalValue) ^ (NSUInteger)(self.internalValue >> 32));
+}
+
+// NOTE: compare: is implemented in NumberValue.
+
+@end
+
+#pragma mark - FSTDoubleValue
+
+@interface FSTDoubleValue ()
+@property(nonatomic, assign, readonly) double internalValue;
+@end
+
+@implementation FSTDoubleValue
+
++ (instancetype)doubleValue:(double)value {
+  // Normalize NaNs to match the behavior on the backend (which uses Double.doubletoLongBits()).
+  if (isnan(value)) {
+    return [FSTDoubleValue nanValue];
+  }
+  return [[FSTDoubleValue alloc] initWithValue:value];
+}
+
++ (instancetype)nanValue {
+  static FSTDoubleValue *sharedInstance = nil;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    sharedInstance = [[FSTDoubleValue alloc] initWithValue:NAN];
+  });
+  return sharedInstance;
+}
+
+- (id)initWithValue:(double)value {
+  self = [super init];
+  if (self) {
+    _internalValue = value;
+  }
+  return self;
+}
+
+- (id)value {
+  return @(self.internalValue);
+}
+
+- (BOOL)isEqual:(id)other {
+  // NOTE: DoubleValue and LongValue instances may compare: the same, but that doesn't make them
+  // equal via isEqual:
+
+  // NOTE: isEqual: should compare NaN equal to itself and -0.0 not equal to 0.0.
+
+  return [other isKindOfClass:[FSTDoubleValue class]] &&
+         FSTDoubleBitwiseEquals(self.internalValue, ((FSTDoubleValue *)other).internalValue);
+}
+
+- (NSUInteger)hash {
+  return FSTDoubleBitwiseHash(self.internalValue);
+}
+
+// NOTE: compare: is implemented in NumberValue.
+
+@end
+
+#pragma mark - FSTStringValue
+
+@interface FSTStringValue ()
+@property(nonatomic, copy, readonly) NSString *internalValue;
+@end
+
+// TODO(b/37267885): Add truncation support
+@implementation FSTStringValue
+
++ (instancetype)stringValue:(NSString *)value {
+  return [[FSTStringValue alloc] initWithValue:value];
+}
+
+- (id)initWithValue:(NSString *)value {
+  self = [super init];
+  if (self) {
+    _internalValue = [value copy];
+  }
+  return self;
+}
+
+- (FSTTypeOrder)typeOrder {
+  return FSTTypeOrderString;
+}
+
+- (id)value {
+  return self.internalValue;
+}
+
+- (BOOL)isEqual:(id)other {
+  return [other isKindOfClass:[FSTStringValue class]] &&
+         [self.internalValue isEqualToString:((FSTStringValue *)other).internalValue];
+}
+
+- (NSUInteger)hash {
+  return self.internalValue ? 1 : 0;
+}
+
+- (NSComparisonResult)compare:(FSTFieldValue *)other {
+  if ([other isKindOfClass:[FSTStringValue class]]) {
+    return FSTCompareStrings(self.internalValue, ((FSTStringValue *)other).internalValue);
+  } else {
+    return [self defaultCompare:other];
+  }
+}
+
+@end
+
+#pragma mark - FSTTimestampValue
+
+@interface FSTTimestampValue ()
+@property(nonatomic, strong, readonly) FSTTimestamp *internalValue;
+@end
+
+@implementation FSTTimestampValue
+
++ (instancetype)timestampValue:(FSTTimestamp *)value {
+  return [[FSTTimestampValue alloc] initWithValue:value];
+}
+
+- (id)initWithValue:(FSTTimestamp *)value {
+  self = [super init];
+  if (self) {
+    _internalValue = value;  // FSTTimestamp is immutable.
+  }
+  return self;
+}
+
+- (FSTTypeOrder)typeOrder {
+  return FSTTypeOrderTimestamp;
+}
+
+- (id)value {
+  // For developers, we expose Timestamps as Dates.
+  return self.internalValue.approximateDateValue;
+}
+
+- (BOOL)isEqual:(id)other {
+  return [other isKindOfClass:[FSTTimestampValue class]] &&
+         [self.internalValue isEqual:((FSTTimestampValue *)other).internalValue];
+}
+
+- (NSUInteger)hash {
+  return [self.internalValue hash];
+}
+
+- (NSComparisonResult)compare:(FSTFieldValue *)other {
+  if ([other isKindOfClass:[FSTTimestampValue class]]) {
+    return [self.internalValue compare:((FSTTimestampValue *)other).internalValue];
+  } else if ([other isKindOfClass:[FSTServerTimestampValue class]]) {
+    // Concrete timestamps come before server timestamps.
+    return NSOrderedAscending;
+  } else {
+    return [self defaultCompare:other];
+  }
+}
+
+@end
+
+#pragma mark - FSTServerTimestampValue
+
+@implementation FSTServerTimestampValue
+
++ (instancetype)serverTimestampValueWithLocalWriteTime:(FSTTimestamp *)localWriteTime {
+  return [[FSTServerTimestampValue alloc] initWithLocalWriteTime:localWriteTime];
+}
+
+- (id)initWithLocalWriteTime:(FSTTimestamp *)localWriteTime {
+  self = [super init];
+  if (self) {
+    _localWriteTime = localWriteTime;
+  }
+  return self;
+}
+
+- (FSTTypeOrder)typeOrder {
+  return FSTTypeOrderTimestamp;
+}
+
+- (NSNull *)value {
+  // For developers, server timestamps always evaluate to NSNull (for now, at least; b/62064202).
+  return [NSNull null];
+}
+
+- (BOOL)isEqual:(id)other {
+  return [other isKindOfClass:[FSTServerTimestampValue class]] &&
+         [self.localWriteTime isEqual:((FSTServerTimestampValue *)other).localWriteTime];
+}
+
+- (NSUInteger)hash {
+  return [self.localWriteTime hash];
+}
+
+- (NSString *)description {
+  return [NSString stringWithFormat:@"<ServerTimestamp localTime=%@>", self.localWriteTime];
+}
+
+- (NSComparisonResult)compare:(FSTFieldValue *)other {
+  if ([other isKindOfClass:[FSTServerTimestampValue class]]) {
+    return [self.localWriteTime compare:((FSTServerTimestampValue *)other).localWriteTime];
+  } else if ([other isKindOfClass:[FSTTimestampValue class]]) {
+    // Server timestamps come after all concrete timestamps.
+    return NSOrderedDescending;
+  } else {
+    return [self defaultCompare:other];
+  }
+}
+
+@end
+
+#pragma mark - FSTGeoPointValue
+
+@interface FSTGeoPointValue ()
+@property(nonatomic, strong, readonly) FIRGeoPoint *internalValue;
+@end
+
+@implementation FSTGeoPointValue
+
++ (instancetype)geoPointValue:(FIRGeoPoint *)value {
+  return [[FSTGeoPointValue alloc] initWithValue:value];
+}
+
+- (id)initWithValue:(FIRGeoPoint *)value {
+  self = [super init];
+  if (self) {
+    _internalValue = value;  // FIRGeoPoint is immutable.
+  }
+  return self;
+}
+
+- (FSTTypeOrder)typeOrder {
+  return FSTTypeOrderGeoPoint;
+}
+
+- (id)value {
+  return self.internalValue;
+}
+
+- (BOOL)isEqual:(id)other {
+  return [other isKindOfClass:[FSTGeoPointValue class]] &&
+         [self.internalValue isEqual:((FSTGeoPointValue *)other).internalValue];
+}
+
+- (NSUInteger)hash {
+  return [self.internalValue hash];
+}
+
+- (NSComparisonResult)compare:(FSTFieldValue *)other {
+  if ([other isKindOfClass:[FSTGeoPointValue class]]) {
+    return [self.internalValue compare:((FSTGeoPointValue *)other).internalValue];
+  } else {
+    return [self defaultCompare:other];
+  }
+}
+
+@end
+
+#pragma mark - FSTBlobValue
+
+@interface FSTBlobValue ()
+@property(nonatomic, copy, readonly) NSData *internalValue;
+@end
+
+// TODO(b/37267885): Add truncation support
+@implementation FSTBlobValue
+
++ (instancetype)blobValue:(NSData *)value {
+  return [[FSTBlobValue alloc] initWithValue:value];
+}
+
+- (id)initWithValue:(NSData *)value {
+  self = [super init];
+  if (self) {
+    _internalValue = [value copy];
+  }
+  return self;
+}
+
+- (FSTTypeOrder)typeOrder {
+  return FSTTypeOrderBlob;
+}
+
+- (id)value {
+  return self.internalValue;
+}
+
+- (BOOL)isEqual:(id)other {
+  return [other isKindOfClass:[FSTBlobValue class]] &&
+         [self.internalValue isEqual:((FSTBlobValue *)other).internalValue];
+}
+
+- (NSUInteger)hash {
+  return [self.internalValue hash];
+}
+
+- (NSComparisonResult)compare:(FSTFieldValue *)other {
+  if ([other isKindOfClass:[FSTBlobValue class]]) {
+    return FSTCompareBytes(self.internalValue, ((FSTBlobValue *)other).internalValue);
+  } else {
+    return [self defaultCompare:other];
+  }
+}
+
+@end
+
+#pragma mark - FSTReferenceValue
+
+@interface FSTReferenceValue ()
+@property(nonatomic, strong, readonly) FSTDocumentKey *key;
+@end
+
+@implementation FSTReferenceValue
+
++ (instancetype)referenceValue:(FSTDocumentKey *)value databaseID:(FSTDatabaseID *)databaseID {
+  return [[FSTReferenceValue alloc] initWithValue:value databaseID:databaseID];
+}
+
+- (id)initWithValue:(FSTDocumentKey *)value databaseID:(FSTDatabaseID *)databaseID {
+  self = [super init];
+  if (self) {
+    _key = value;
+    _databaseID = databaseID;
+  }
+  return self;
+}
+
+- (id)value {
+  return self.key;
+}
+
+- (FSTTypeOrder)typeOrder {
+  return FSTTypeOrderReference;
+}
+
+- (BOOL)isEqual:(id)other {
+  if (other == self) {
+    return YES;
+  }
+  if (![other isKindOfClass:[FSTReferenceValue class]]) {
+    return NO;
+  }
+
+  FSTReferenceValue *otherRef = (FSTReferenceValue *)other;
+  return [self.key isEqualToKey:otherRef.key] &&
+         [self.databaseID isEqualToDatabaseId:otherRef.databaseID];
+}
+
+- (NSUInteger)hash {
+  NSUInteger result = [self.databaseID hash];
+  result = 31 * result + [self.key hash];
+  return result;
+}
+
+- (NSComparisonResult)compare:(FSTFieldValue *)other {
+  if ([other isKindOfClass:[FSTReferenceValue class]]) {
+    FSTReferenceValue *ref = (FSTReferenceValue *)other;
+    NSComparisonResult cmp = [self.databaseID compare:ref.databaseID];
+    return cmp != NSOrderedSame ? cmp : [self.key compare:ref.key];
+  } else {
+    return [self defaultCompare:other];
+  }
+}
+
+@end
+
+#pragma mark - FSTObjectValue
+
+@interface FSTObjectValue ()
+@property(nonatomic, strong, readonly)
+    FSTImmutableSortedDictionary<NSString *, FSTFieldValue *> *internalValue;
+@end
+
+@implementation FSTObjectValue
+
++ (instancetype)objectValue {
+  static FSTObjectValue *sharedEmptyInstance = nil;
+  static dispatch_once_t onceToken;
+
+  dispatch_once(&onceToken, ^{
+    FSTImmutableSortedDictionary<NSString *, FSTFieldValue *> *empty =
+        [FSTImmutableSortedDictionary dictionaryWithComparator:FSTStringComparator];
+    sharedEmptyInstance = [[FSTObjectValue alloc] initWithImmutableDictionary:empty];
+  });
+  return sharedEmptyInstance;
+}
+
+- (instancetype)initWithImmutableDictionary:
+    (FSTImmutableSortedDictionary<NSString *, FSTFieldValue *> *)value {
+  self = [super init];
+  if (self) {
+    _internalValue = value;  // FSTImmutableSortedDictionary is immutable.
+  }
+  return self;
+}
+
+- (id)initWithDictionary:(NSDictionary<NSString *, FSTFieldValue *> *)value {
+  FSTImmutableSortedDictionary<NSString *, FSTFieldValue *> *dictionary =
+      [FSTImmutableSortedDictionary dictionaryWithDictionary:value comparator:FSTStringComparator];
+  return [self initWithImmutableDictionary:dictionary];
+}
+
+- (id)value {
+  NSMutableDictionary *result = [NSMutableDictionary dictionary];
+  [self.internalValue
+      enumerateKeysAndObjectsUsingBlock:^(NSString *key, FSTFieldValue *obj, BOOL *stop) {
+        result[key] = [obj value];
+      }];
+  return result;
+}
+
+- (FSTTypeOrder)typeOrder {
+  return FSTTypeOrderObject;
+}
+
+- (BOOL)isEqual:(id)other {
+  if (other == self) {
+    return YES;
+  }
+  if (![other isKindOfClass:[FSTObjectValue class]]) {
+    return NO;
+  }
+
+  FSTObjectValue *otherObj = other;
+  return [self.internalValue isEqual:otherObj.internalValue];
+}
+
+- (NSUInteger)hash {
+  return [self.internalValue hash];
+}
+
+- (NSComparisonResult)compare:(FSTFieldValue *)other {
+  if ([other isKindOfClass:[FSTObjectValue class]]) {
+    FSTImmutableSortedDictionary *selfDict = self.internalValue;
+    FSTImmutableSortedDictionary *otherDict = ((FSTObjectValue *)other).internalValue;
+    NSEnumerator *enumerator1 = [selfDict keyEnumerator];
+    NSEnumerator *enumerator2 = [otherDict keyEnumerator];
+    NSString *key1 = [enumerator1 nextObject];
+    NSString *key2 = [enumerator2 nextObject];
+    while (key1 && key2) {
+      NSComparisonResult keyCompare = [key1 compare:key2];
+      if (keyCompare != NSOrderedSame) {
+        return keyCompare;
+      }
+      NSComparisonResult valueCompare = [selfDict[key1] compare:otherDict[key2]];
+      if (valueCompare != NSOrderedSame) {
+        return valueCompare;
+      }
+      key1 = [enumerator1 nextObject];
+      key2 = [enumerator2 nextObject];
+    }
+    // Only equal if both enumerators are exhausted.
+    return FSTCompareBools(key1 != nil, key2 != nil);
+  } else {
+    return [self defaultCompare:other];
+  }
+}
+
+- (nullable FSTFieldValue *)valueForPath:(FSTFieldPath *)fieldPath {
+  FSTFieldValue *value = self;
+  for (int i = 0, max = fieldPath.length; value && i < max; i++) {
+    if (![value isMemberOfClass:[FSTObjectValue class]]) {
+      return nil;
+    }
+
+    NSString *fieldName = fieldPath[i];
+    value = ((FSTObjectValue *)value).internalValue[fieldName];
+  }
+
+  return value;
+}
+
+- (FSTObjectValue *)objectBySettingValue:(FSTFieldValue *)value forPath:(FSTFieldPath *)fieldPath {
+  FSTAssert([fieldPath length] > 0, @"Cannot set value with an empty path");
+
+  NSString *childName = [fieldPath firstSegment];
+  if ([fieldPath length] == 1) {
+    // Recursive base case:
+    return [self objectBySettingValue:value forField:childName];
+  } else {
+    // Nested path. Recursively generate a new sub-object and then wrap a new FSTObjectValue around
+    // the result.
+    FSTFieldValue *child = [_internalValue objectForKey:childName];
+    FSTObjectValue *childObject;
+    if ([child isKindOfClass:[FSTObjectValue class]]) {
+      childObject = (FSTObjectValue *)child;
+    } else {
+      // If the child is not found or is a primitive type, pretend as if an empty object lived
+      // there.
+      childObject = [FSTObjectValue objectValue];
+    }
+    FSTFieldValue *newChild =
+        [childObject objectBySettingValue:value forPath:[fieldPath pathByRemovingFirstSegment]];
+    return [self objectBySettingValue:newChild forField:childName];
+  }
+}
+
+- (FSTObjectValue *)objectByDeletingPath:(FSTFieldPath *)fieldPath {
+  FSTAssert([fieldPath length] > 0, @"Cannot delete an empty path");
+  NSString *childName = [fieldPath firstSegment];
+  if ([fieldPath length] == 1) {
+    return [[FSTObjectValue alloc]
+        initWithImmutableDictionary:[_internalValue dictionaryByRemovingObjectForKey:childName]];
+  } else {
+    FSTFieldValue *child = _internalValue[childName];
+    if ([child isKindOfClass:[FSTObjectValue class]]) {
+      FSTObjectValue *newChild =
+          [((FSTObjectValue *)child) objectByDeletingPath:[fieldPath pathByRemovingFirstSegment]];
+      return [self objectBySettingValue:newChild forField:childName];
+    } else {
+      // If the child is not found or is a primitive type, make no modifications
+      return self;
+    }
+  }
+}
+
+- (FSTObjectValue *)objectBySettingValue:(FSTFieldValue *)value forField:(NSString *)field {
+  return [[FSTObjectValue alloc]
+      initWithImmutableDictionary:[_internalValue dictionaryBySettingObject:value forKey:field]];
+}
+
+@end
+
+@interface FSTArrayValue ()
+@property(nonatomic, strong, readonly) NSArray<FSTFieldValue *> *internalValue;
+@end
+
+#pragma mark - FSTArrayValue
+
+@implementation FSTArrayValue
+
+- (id)initWithValueNoCopy:(NSArray<FSTFieldValue *> *)value {
+  self = [super init];
+  if (self) {
+    // Does not copy, assumes the caller has already copied.
+    _internalValue = value;
+  }
+  return self;
+}
+
+- (BOOL)isEqual:(id)other {
+  if (other == self) {
+    return YES;
+  }
+  if (![other isKindOfClass:[self class]]) {
+    return NO;
+  }
+
+  // NSArray's isEqual does the right thing for our purposes.
+  FSTArrayValue *otherArray = other;
+  return [self.internalValue isEqual:otherArray.internalValue];
+}
+
+- (NSUInteger)hash {
+  return [self.internalValue hash];
+}
+
+- (id)value {
+  NSMutableArray *result = [NSMutableArray arrayWithCapacity:_internalValue.count];
+  [self.internalValue enumerateObjectsUsingBlock:^(FSTFieldValue *obj, NSUInteger idx, BOOL *stop) {
+    [result addObject:[obj value]];
+  }];
+  return result;
+}
+
+- (FSTTypeOrder)typeOrder {
+  return FSTTypeOrderArray;
+}
+
+- (NSComparisonResult)compare:(FSTFieldValue *)other {
+  if ([other isKindOfClass:[FSTArrayValue class]]) {
+    NSArray<FSTFieldValue *> *selfArray = self.internalValue;
+    NSArray<FSTFieldValue *> *otherArray = ((FSTArrayValue *)other).internalValue;
+    NSUInteger minLength = MIN(selfArray.count, otherArray.count);
+    for (NSUInteger i = 0; i < minLength; i++) {
+      NSComparisonResult cmp = [selfArray[i] compare:otherArray[i]];
+      if (cmp != NSOrderedSame) {
+        return cmp;
+      }
+    }
+    return FSTCompareUIntegers(selfArray.count, otherArray.count);
+  } else {
+    return [self defaultCompare:other];
+  }
+}
+
+@end
+
+NS_ASSUME_NONNULL_END