[ios, macos] Add trigonometric support to NSExpression. (#11716)

* [ios, macos] Add acos NSExpresssion operator.

* [ios, macos] Add asin NSExpresssion operator.

* [ios, macos] Add atan NSExpresssion operator.

* [ios, macos] Add cosine NSExpresssion operator.

* [ios, macos] Add sine NSExpresssion operator.

* [ios, macos] Add tangent NSExpresssion operator.

* [ios, macos] Add log2 NSExpresssion operator.

* [ios, macos] Update style authors documentation.

5 files changed, 141 insertions, 21 deletions

diff --git a/platform/darwin/docs/guides/For Style Authors.md.ejs b/platform/darwin/docs/guides/For Style Authors.md.ejs
index a3083571cf..bca894c063 100644
--- a/platform/darwin/docs/guides/For Style Authors.md.ejs
+++ b/platform/darwin/docs/guides/For Style Authors.md.ejs
@@ -380,24 +380,24 @@ In style specification | Method, function, or predicate type | Format string syn
 `^`                    | `raise:toPower:` | `2 ** 2`
 `+`                    | `add:to:` | `1 + 2`
 `abs`                  | `abs:` | `abs(-1)`
-`acos`                 | |
-`asin`                 | |
-`atan`                 | |
+`acos`                 | `mgl_acos:` | `mgl_acos(1)`
+`asin`                 | `mgl_asin:` | `mgl_asin(0)`
+`atan`                 | `mgl_atan:` | `mgl_atan(20)`
 `ceil`                 | `ceiling:` | `ceiling(0.99999)`
-`cos`                  | |
+`cos`                  | `mgl_cos:` | `mgl_cos(0)`
 `e`                    | | `%@` representing `NSNumber` containing `M_E`
 `floor`                | `floor:` | `floor(-0.99999)`
 `ln`                   | `ln:` | `ln(2)`
 `ln2`                  | | `%@` representing `NSNumber` containing `M_LN2`
 `log10`                | `log:` | `log(1)`
-`log2`                 | |
+`log2`                 | `mgl_log2:` | `mgl_log2(1024)`
 `max`                  | `max:` | `max({1, 2, 2, 3, 4, 7, 9})`
 `min`                  | `min:` | `min({1, 2, 2, 3, 4, 7, 9})`
 `pi`                   | | `%@` representing `NSNumber` containing `M_PI`
 `round`                | `mgl_round:` | `mgl_round(1.5)`
-`sin`                  | |
+`sin`                  | `mgl_sin:` | `mgl_sin(0)`
 `sqrt`                 | `sqrt:` | `sqrt(2)`
-`tan`                  | |
+`tan`                  | `mgl_tan:` | `mgl_tan(0)`
 `zoom`                 | `NSExpression.zoomLevelVariableExpression` | `$zoom`
 `heatmap-density`      | `NSExpression.heatmapDensityVariableExpression` | `$heatmapDensity`
 
diff --git a/platform/darwin/src/NSExpression+MGLAdditions.mm b/platform/darwin/src/NSExpression+MGLAdditions.mm
index 54f98c6ab9..46a463430b 100644
--- a/platform/darwin/src/NSExpression+MGLAdditions.mm
+++ b/platform/darwin/src/NSExpression+MGLAdditions.mm
@@ -68,6 +68,13 @@ const MGLExpressionInterpolationMode MGLExpressionInterpolationModeCubicBezier =
     INSTALL_METHOD(mgl_step:from:stops:);
     INSTALL_METHOD(mgl_coalesce:);
     INSTALL_METHOD(mgl_does:have:);
+    INSTALL_METHOD(mgl_acos:);
+    INSTALL_METHOD(mgl_cos:);
+    INSTALL_METHOD(mgl_asin:);
+    INSTALL_METHOD(mgl_sin:);
+    INSTALL_METHOD(mgl_atan:);
+    INSTALL_METHOD(mgl_tan:);
+    INSTALL_METHOD(mgl_log2:);
     
     // Install functions that resemble control structures, taking arbitrary
     // numbers of arguments. Vararg aftermarket functions need to be declared
@@ -98,6 +105,55 @@ const MGLExpressionInterpolationMode MGLExpressionInterpolationModeCubicBezier =
 }
 
 /**
+  Computes the principal value of the inverse cosine.
+ */
+- (NSNumber *)mgl_acos:(NSNumber *)number {
+    return @(acos(number.doubleValue));
+}
+
+/**
+ Computes the principal value of the cosine.
+ */
+- (NSNumber *)mgl_cos:(NSNumber *)number {
+    return @(cos(number.doubleValue));
+}
+
+/**
+ Computes the principal value of the inverse sine.
+ */
+- (NSNumber *)mgl_asin:(NSNumber *)number {
+    return @(asin(number.doubleValue));
+}
+
+/**
+ Computes the principal value of the sine.
+ */
+- (NSNumber *)mgl_sin:(NSNumber *)number {
+    return @(sin(number.doubleValue));
+}
+
+/**
+ Computes the principal value of the inverse tangent.
+ */
+- (NSNumber *)mgl_atan:(NSNumber *)number {
+    return @(atan(number.doubleValue));
+}
+
+/**
+ Computes the principal value of the tangent.
+ */
+- (NSNumber *)mgl_tan:(NSNumber *)number {
+    return @(tan(number.doubleValue));
+}
+
+/**
+ Computes the logarithm base two of the value.
+ */
+- (NSNumber *)mgl_log2:(NSNumber *)number {
+    return @(log2(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 +731,13 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
             @"ln": @"ln:",
             @"abs": @"abs:",
             @"round": @"mgl_round:",
+            @"acos" : @"mgl_acos:",
+            @"cos" : @"mgl_cos:",
+            @"asin" : @"mgl_asin:",
+            @"sin" : @"mgl_sin:",
+            @"atan" : @"mgl_atan:",
+            @"tan" : @"mgl_tan:",
+            @"log2" : @"mgl_log2:",
             @"floor": @"floor:",
             @"ceil": @"ceiling:",
             @"^": @"raise:toPower:",
@@ -917,6 +980,13 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
             @"lowercase:": @"downcase",
             @"length:": @"length",
             @"mgl_round:": @"round",
+            @"mgl_acos:" : @"acos",
+            @"mgl_cos:" : @"cos",
+            @"mgl_asin:" : @"asin",
+            @"mgl_sin:" : @"sin",
+            @"mgl_atan:" : @"atan",
+            @"mgl_tan:" : @"tan",
+            @"mgl_log2:" : @"log2",
             // 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..d7c86ed07c 100644
--- a/platform/darwin/test/MGLExpressionTests.mm
+++ b/platform/darwin/test/MGLExpressionTests.mm
@@ -504,6 +504,13 @@ using namespace std::string_literals;
         XCTAssertEqualObjects([NSExpression expressionWithMGLJSONObject:jsonExpression], expression);
     }
     {
+        NSExpression *expression = [NSExpression expressionForFunction:@"mgl_log2:" arguments:@[MGLConstantExpression(@1024)]];
+        NSArray *jsonExpression = @[@"log2", @1024];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @10);
+        XCTAssertEqualObjects([NSExpression expressionWithMGLJSONObject:jsonExpression], expression);
+    }
+    {
         NSExpression *expression = [NSExpression expressionForFunction:@"raise:toPower:" arguments:arguments];
         NSArray *jsonExpression = @[@"^", @1, @1];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
@@ -531,6 +538,49 @@ 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);
+    }
+    {
+        NSExpression *expression = [NSExpression expressionForFunction:@"mgl_cos:" arguments:@[MGLConstantExpression(@0)]];
+        NSArray *jsonExpression = @[@"cos", @0];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @1);
+        XCTAssertEqualObjects([NSExpression expressionWithMGLJSONObject:jsonExpression], expression);
+    }
+    {
+        NSExpression *expression = [NSExpression expressionForFunction:@"mgl_asin:" arguments:@[MGLConstantExpression(@0)]];
+        NSArray *jsonExpression = @[@"asin", @0];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @0);
+        XCTAssertEqualObjects([NSExpression expressionWithMGLJSONObject:jsonExpression], expression);
+    }
+    {
+        NSExpression *expression = [NSExpression expressionForFunction:@"mgl_sin:" arguments:@[MGLConstantExpression(@0)]];
+        NSArray *jsonExpression = @[@"sin", @0];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @0);
+        XCTAssertEqualObjects([NSExpression expressionWithMGLJSONObject:jsonExpression], expression);
+    }
+    {
+        NSExpression *expression = [NSExpression expressionForFunction:@"mgl_atan:" arguments:@[MGLConstantExpression(@20)]];
+        NSArray *jsonExpression = @[@"atan", @20];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        NSNumber *value = [expression expressionValueWithObject:nil context:nil];
+        XCTAssertEqualWithAccuracy(value.doubleValue, 1.52, 0.001);
+        XCTAssertEqualObjects([NSExpression expressionWithMGLJSONObject:jsonExpression], expression);
+    }
+    {
+        NSExpression *expression = [NSExpression expressionForFunction:@"mgl_tan:" arguments:@[MGLConstantExpression(@0)]];
+        NSArray *jsonExpression = @[@"tan", @0];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @0);
+        XCTAssertEqualObjects([NSExpression expressionWithMGLJSONObject:jsonExpression], expression);
+    }
 }
 
 - (void)testStringFormattingExpressionObject {
diff --git a/platform/ios/docs/guides/For Style Authors.md b/platform/ios/docs/guides/For Style Authors.md
index 1ce0a4bf4f..fa65b3ccb9 100644
--- a/platform/ios/docs/guides/For Style Authors.md
+++ b/platform/ios/docs/guides/For Style Authors.md
@@ -365,24 +365,24 @@ In style specification | Method, function, or predicate type | Format string syn
 `^`                    | `raise:toPower:` | `2 ** 2`
 `+`                    | `add:to:` | `1 + 2`
 `abs`                  | `abs:` | `abs(-1)`
-`acos`                 | |
-`asin`                 | |
-`atan`                 | |
+`acos`                 | `mgl_acos:` | `mgl_acos(1)`
+`asin`                 | `mgl_asin:` | `mgl_asin(0)`
+`atan`                 | `mgl_atan:` | `mgl_atan(20)`
 `ceil`                 | `ceiling:` | `ceiling(0.99999)`
-`cos`                  | |
+`cos`                  | `mgl_cos:` | `mgl_cos(0)`
 `e`                    | | `%@` representing `NSNumber` containing `M_E`
 `floor`                | `floor:` | `floor(-0.99999)`
 `ln`                   | `ln:` | `ln(2)`
 `ln2`                  | | `%@` representing `NSNumber` containing `M_LN2`
 `log10`                | `log:` | `log(1)`
-`log2`                 | |
+`log2`                 | `mgl_log2:` | `mgl_log2(1024)`
 `max`                  | `max:` | `max({1, 2, 2, 3, 4, 7, 9})`
 `min`                  | `min:` | `min({1, 2, 2, 3, 4, 7, 9})`
 `pi`                   | | `%@` representing `NSNumber` containing `M_PI`
 `round`                | `mgl_round:` | `mgl_round(1.5)`
-`sin`                  | |
+`sin`                  | `mgl_sin:` | `mgl_sin(0)`
 `sqrt`                 | `sqrt:` | `sqrt(2)`
-`tan`                  | |
+`tan`                  | `mgl_tan:` | `mgl_tan(0)`
 `zoom`                 | `NSExpression.zoomLevelVariableExpression` | `$zoom`
 `heatmap-density`      | `NSExpression.heatmapDensityVariableExpression` | `$heatmapDensity`
 
diff --git a/platform/macos/docs/guides/For Style Authors.md b/platform/macos/docs/guides/For Style Authors.md
index c8e517a5bd..fff70d0a90 100644
--- a/platform/macos/docs/guides/For Style Authors.md
+++ b/platform/macos/docs/guides/For Style Authors.md
@@ -358,24 +358,24 @@ In style specification | Method, function, or predicate type | Format string syn
 `^`                    | `raise:toPower:` | `2 ** 2`
 `+`                    | `add:to:` | `1 + 2`
 `abs`                  | `abs:` | `abs(-1)`
-`acos`                 | |
-`asin`                 | |
-`atan`                 | |
+`acos`                 | `mgl_acos:` | `mgl_acos(1)`
+`asin`                 | `mgl_asin:` | `mgl_asin(0)`
+`atan`                 | `mgl_atan:` | `mgl_atan(20)`
 `ceil`                 | `ceiling:` | `ceiling(0.99999)`
-`cos`                  | |
+`cos`                  | `mgl_cos:` | `mgl_cos(0)`
 `e`                    | | `%@` representing `NSNumber` containing `M_E`
 `floor`                | `floor:` | `floor(-0.99999)`
 `ln`                   | `ln:` | `ln(2)`
 `ln2`                  | | `%@` representing `NSNumber` containing `M_LN2`
 `log10`                | `log:` | `log(1)`
-`log2`                 | |
+`log2`                 | `mgl_log2:` | `mgl_log2(1024)`
 `max`                  | `max:` | `max({1, 2, 2, 3, 4, 7, 9})`
 `min`                  | `min:` | `min({1, 2, 2, 3, 4, 7, 9})`
 `pi`                   | | `%@` representing `NSNumber` containing `M_PI`
 `round`                | `mgl_round:` | `mgl_round(1.5)`
-`sin`                  | |
+`sin`                  | `mgl_sin:` | `mgl_sin(0)`
 `sqrt`                 | `sqrt:` | `sqrt(2)`
-`tan`                  | |
+`tan`                  | `mgl_tan:` | `mgl_tan(0)`
 `zoom`                 | `NSExpression.zoomLevelVariableExpression` | `$zoom`
 `heatmap-density`      | `NSExpression.heatmapDensityVariableExpression` | `$heatmapDensity`