[ios, macos] Add acos NSExpresssion operator.

2 files changed, 17 insertions, 0 deletions

diff --git a/platform/darwin/src/NSExpression+MGLAdditions.mm b/platform/darwin/src/NSExpression+MGLAdditions.mm
index 54f98c6ab9..9238a291a4 100644
--- a/platform/darwin/src/NSExpression+MGLAdditions.mm
+++ b/platform/darwin/src/NSExpression+MGLAdditions.mm
@@ -68,6 +68,7 @@ const MGLExpressionInterpolationMode MGLExpressionInterpolationModeCubicBezier =
     INSTALL_METHOD(mgl_step:from:stops:);
     INSTALL_METHOD(mgl_coalesce:);
     INSTALL_METHOD(mgl_does:have:);
+    INSTALL_METHOD(mgl_acos:);
     
     // Install functions that resemble control structures, taking arbitrary
     // numbers of arguments. Vararg aftermarket functions need to be declared
@@ -98,6 +99,13 @@ const MGLExpressionInterpolationMode MGLExpressionInterpolationModeCubicBezier =
 }
 
 /**
+  Computes the principal value of the arc cosine of number.
+ */
+- (NSNumber *)mgl_acos:(NSNumber *)number {
+    return @(acos(number.doubleValue));
+}
+
+/**
  A placeholder for a method that evaluates an interpolation expression.
  */
 - (id)mgl_interpolate:(id)inputExpression withCurveType:(NSString *)curveType parameters:(NSDictionary *)params stops:(NSDictionary *)stops {
@@ -675,6 +683,7 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
             @"ln": @"ln:",
             @"abs": @"abs:",
             @"round": @"mgl_round:",
+            @"acos" : @"mgl_acos:",
             @"floor": @"floor:",
             @"ceil": @"ceiling:",
             @"^": @"raise:toPower:",
@@ -917,6 +926,7 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
             @"lowercase:": @"downcase",
             @"length:": @"length",
             @"mgl_round:": @"round",
+            @"mgl_acos:" : @"acos",
             // Vararg aftermarket expressions need to be declared with an explicit and implicit first argument.
             @"MGL_LET": @"let",
             @"MGL_LET:": @"let",
diff --git a/platform/darwin/test/MGLExpressionTests.mm b/platform/darwin/test/MGLExpressionTests.mm
index e078c4f4b6..04198dbfc3 100644
--- a/platform/darwin/test/MGLExpressionTests.mm
+++ b/platform/darwin/test/MGLExpressionTests.mm
@@ -531,6 +531,13 @@ using namespace std::string_literals;
         XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @(M_PI));
         XCTAssertEqualObjects([NSExpression expressionWithMGLJSONObject:jsonExpression], expression);
     }
+    {
+        NSExpression *expression = [NSExpression expressionForFunction:@"mgl_acos:" arguments:@[MGLConstantExpression(@1)]];
+        NSArray *jsonExpression = @[@"acos", @1];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @0);
+        XCTAssertEqualObjects([NSExpression expressionWithMGLJSONObject:jsonExpression], expression);
+    }
 }
 
 - (void)testStringFormattingExpressionObject {