[ios, macos] Add match expressions support. (#11464)

* [ios, macos] Add match expressions support.

* [ios, macos] Add coalesce operator support.

* [ios, macos] Add coalesce operator test.

* [ios, macos] Match operator implementation is moved to NSPredicate.

* [ios, macos] Match operator function implementation refactor.

* [ios, macos] Address merge conflicts.

5 files changed, 87 insertions, 3 deletions

diff --git a/platform/darwin/src/NSExpression+MGLAdditions.mm b/platform/darwin/src/NSExpression+MGLAdditions.mm
index bd747dc97e..9797709b7b 100644
--- a/platform/darwin/src/NSExpression+MGLAdditions.mm
+++ b/platform/darwin/src/NSExpression+MGLAdditions.mm
@@ -258,6 +258,12 @@
     return [self valueForKeyPath:@"mgl_jsonExpressionObject"];
 }
 
+- (id)mgl_coalesce {
+    [NSException raise:NSInvalidArgumentException
+                format:@"Coalesce expressions lack underlying Objective-C implementations."];
+    return nil;
+}
+
 @end
 
 @implementation NSDictionary (MGLExpressionAdditions)
@@ -476,11 +482,31 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
                 } else {
                     [arguments addObject:[NSExpression mgl_expressionWithJSONObject:caseExpressions[index]]];
                 }
-                
             }
             
             return [NSExpression expressionForFunction:firstConditional selectorName:@"mgl_case:" arguments:arguments];
-        } else {
+        } else if ([op isEqualToString:@"match"]) {
+            NSExpression *operand = [NSExpression mgl_expressionWithJSONObject:argumentObjects[0]];
+            NSArray *matchOptions = [argumentObjects subarrayWithRange:NSMakeRange(1, argumentObjects.count - 1)];
+
+            NSMutableArray *optionsArray = [NSMutableArray array];
+            NSEnumerator *optionsEnumerator = matchOptions.objectEnumerator;
+            while (id object = optionsEnumerator.nextObject) {
+                NSExpression *option = [NSExpression mgl_expressionWithJSONObject:object];
+                [optionsArray addObject:option];
+            }
+        
+            return [NSExpression expressionForFunction:operand
+                                          selectorName:@"mgl_match:"
+                                             arguments:optionsArray];
+        } else if ([op isEqualToString:@"coalesce"]) {
+            NSMutableArray *expressions = [NSMutableArray array];
+            for (id operand in argumentObjects) {
+                [expressions addObject:[NSExpression mgl_expressionWithJSONObject:operand]];
+            }
+            
+            return [NSExpression expressionWithFormat:@"FUNCTION(%@, 'mgl_coalesce')", expressions];
+        }else {
             [NSException raise:NSInvalidArgumentException
                         format:@"Expression operator %@ not yet implemented.", op];
         }
@@ -674,7 +700,7 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
             } else if ([function isEqualToString:@"mgl_case:"]) {
                 NSPredicate *firstConditional = (NSPredicate *)self.operand.constantValue;
                 NSMutableArray *expressionObject = [NSMutableArray arrayWithObjects:@"case", firstConditional.mgl_jsonExpressionObject, nil];
-                
+
                 for (NSExpression *option in self.arguments) {
                     if ([option respondsToSelector:@selector(constantValue)] && [option.constantValue isKindOfClass:[NSComparisonPredicate class]]) {
                         NSPredicate *predicate = (NSPredicate *)option.constantValue;
@@ -683,6 +709,23 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
                         [expressionObject addObject:option.mgl_jsonExpressionObject];
                     }
                 }
+
+                return expressionObject;
+            } else if ([function isEqualToString:@"mgl_match:"]) {
+                NSMutableArray *expressionObject = [NSMutableArray arrayWithObjects:@"match", self.operand.mgl_jsonExpressionObject, nil];
+                
+
+                for (NSExpression *option in self.arguments) {
+                    [expressionObject addObject:option.mgl_jsonExpressionObject];
+                }
+                
+                return expressionObject;
+            } else if ([function isEqualToString:@"mgl_coalesce"]) {
+                NSMutableArray *expressionObject = [NSMutableArray arrayWithObjects:@"coalesce", nil];
+                
+                for (NSExpression *expression in self.operand.constantValue) {
+                    [expressionObject addObject:[expression mgl_jsonExpressionObject]];
+                }
                 
                 return expressionObject;
             } else if ([function isEqualToString:@"median:"] ||
diff --git a/platform/darwin/src/NSExpression+MGLPrivateAdditions.h b/platform/darwin/src/NSExpression+MGLPrivateAdditions.h
index 8d1b4d6af5..b16e2625a0 100644
--- a/platform/darwin/src/NSExpression+MGLPrivateAdditions.h
+++ b/platform/darwin/src/NSExpression+MGLPrivateAdditions.h
@@ -54,6 +54,8 @@ NS_ASSUME_NONNULL_BEGIN
 
 @property (nonatomic, readonly) id mgl_jsonExpressionObject;
 
+@property (nonatomic, readonly) id mgl_coalesce;
+
 @end
 
 @interface NSDictionary (MGLExpressionAdditions)
diff --git a/platform/darwin/src/NSPredicate+MGLAdditions.h b/platform/darwin/src/NSPredicate+MGLAdditions.h
index cce7561add..a67c6ca005 100644
--- a/platform/darwin/src/NSPredicate+MGLAdditions.h
+++ b/platform/darwin/src/NSPredicate+MGLAdditions.h
@@ -18,4 +18,6 @@
 
 - (id)mgl_case:(id)firstValue, ...;
 
+- (id)mgl_match:(NSExpression *)firstCase, ...;
+
 @end
diff --git a/platform/darwin/src/NSPredicate+MGLAdditions.mm b/platform/darwin/src/NSPredicate+MGLAdditions.mm
index 2d5b646ff2..1a7bb30a92 100644
--- a/platform/darwin/src/NSPredicate+MGLAdditions.mm
+++ b/platform/darwin/src/NSPredicate+MGLAdditions.mm
@@ -349,4 +349,10 @@ NSArray *MGLSubpredicatesWithJSONObjects(NSArray *objects) {
     return nil;
 }
 
+- (id)mgl_match:(NSExpression *)firstCase, ... {
+    [NSException raise:NSInvalidArgumentException
+                format:@"Match expressions lack underlying Objective-C implementations."];
+    return nil;
+}
+
 @end
diff --git a/platform/darwin/test/MGLExpressionTests.mm b/platform/darwin/test/MGLExpressionTests.mm
index 3f36a0cf61..ea5a1cd41c 100644
--- a/platform/darwin/test/MGLExpressionTests.mm
+++ b/platform/darwin/test/MGLExpressionTests.mm
@@ -572,6 +572,37 @@ using namespace std::string_literals;
     }
 }
 
+- (void)testMatchExpressionObject {
+    {
+        NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION(2 - 1, 'mgl_match:', %@, %@, %@, %@, 'default')", MGLConstantExpression(@1),
+                                    MGLConstantExpression(@"one"),
+                                    MGLConstantExpression(@0),
+                                    MGLConstantExpression(@"zero")];
+        NSArray *jsonExpression =  @[@"match", @[@"-", @2, @1], @1, @"one", @0, @"zero", @"default"];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
+    }
+    {
+        NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION(2 * 1, 'mgl_match:', %@, %@, 'default')", MGLConstantExpression(@1), MGLConstantExpression(@"one")];
+        NSArray *jsonExpression =  @[@"match", @[@"*", @2, @1], @1, @"one", @"default"];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
+    }
+}
+
+- (void)testCoalesceExpressionObject {
+    {
+        NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION(%@, 'mgl_coalesce')", @[[NSExpression expressionForKeyPath:@"x"],
+                                                                                                     [NSExpression expressionForKeyPath:@"y"],
+                                                                                                     [NSExpression expressionForKeyPath:@"z"],
+                                                                                                     [NSExpression expressionForConstantValue:@0]]];
+        NSArray *jsonExpression = @[@"coalesce", @[@"get", @"x"], @[@"get", @"y"], @[@"get", @"z"], @0];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
+    }
+    
+}
+
 - (void)testConditionalExpressionObject {
     {
         NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION(%@, 'mgl_case:', %@, %@)",