[ios, macos] Added rounding expression function

platform/darwin/docs/guides/For Style Authors.md.ejs

@@ -394,7 +394,7 @@ In style specification | Method, function, or predicate type | Format string syn
 `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`                | |
+`round`                | `mgl_round:` | `mgl_round(1.5)`
 `sin`                  | |
 `sqrt`                 | `sqrt:` | `sqrt(2)`
 `tan`                  | |

platform/darwin/docs/guides/Predicates and Expressions.md

@@ -196,6 +196,7 @@ Initializer parameter | Format string syntax | Description
 `mgl_interpolate:withCurveType:parameters:stops:` | `mgl_interpolate:withCurveType:parameters:stops:(x, 'linear', nil, %@)` | Produces continuous, smooth results by interpolating between pairs of input and output values (“stops”). Compared to the `mgl_interpolateWithCurveType:parameters:stops:` custom function, the input expression (that function’s target) is instead passed in as the first argument to this function.
 `mgl_step:from:stops:` | `mgl_step:from:stops:(x, 11, %@)` | Produces discrete, stepped results by evaluating a piecewise-constant function defined by pairs of input and output values ("stops"). Compared to the `mgl_stepWithMinimum:stops:` custom function, the input expression (that function’s target) is instead passed in as the first argument to this function.
 `mgl_join:` | `mgl_join({'Old', 'MacDonald'})` | Returns the result of concatenating together all the elements of an array in order. Compared to the `stringByAppendingString:` custom function, this function takes only one argument, which is an aggregate expression containing the strings to concatenate.
+`mgl_round:` | `mgl_round(1.5)` | Returns the number rounded to the nearest integer. If the number is halfway between two integers, this function rounds it away from zero.
 `mgl_coalesce:` | `mgl_coalesce({x, y, z})` | Returns the first non-`nil` value from an array of expressions.
 `MGL_LET` | `MGL_LET('age', uppercase('old'), 'name', uppercase('MacDonald'), mgl_join({$age, $name}))` | Any number of variable names interspersed with their assigned `NSExpression` values, followed by an `NSExpression` that may contain references to those variables. Compared to the `mgl_expressionWithContext:` custom function, this function takes the variable names and values inline before the expression that contains references to those variables.
 `MGL_MATCH` | `MGL_MATCH(x, 0, 'zero match', 1, 'one match', 'two match', 'default')` | Evaluates the first expression and returns the value that matches the initial condition. After the first expression condition a pair of matching/return value should be added and a default value.

platform/darwin/src/NSExpression+MGLAdditions.mm

@@ -58,6 +58,7 @@ + (void)installFunctions {
     // Install method-like functions, taking the number of arguments implied by
     // the selector name.
     INSTALL_METHOD(mgl_join:);
+    INSTALL_METHOD(mgl_round:);
     INSTALL_METHOD(mgl_interpolate:withCurveType:parameters:stops:);
     INSTALL_METHOD(mgl_step:from:stops:);
     INSTALL_METHOD(mgl_coalesce:);
@@ -83,6 +84,14 @@ - (NSString *)mgl_join:(NSArray<NSString *> *)components {
     return [components componentsJoinedByString:@""];
 }
 
+/**
+ Rounds the given number to the nearest integer. If the number is halfway
+ between two integers, this method rounds it away from zero.
+ */
+- (NSNumber *)mgl_round:(NSNumber *)number {
+    return @(round(number.doubleValue));
+}
+
 /**
  A placeholder for a method that evaluates an interpolation expression.
  */
@@ -488,6 +497,7 @@ + (instancetype)mgl_expressionWithJSONObject:(id)object {
             @"log10": @"log:",
             @"ln": @"ln:",
             @"abs": @"abs:",
+            @"round": @"mgl_round:",
             @"floor": @"floor:",
             @"ceil": @"ceiling:",
             @"^": @"raise:toPower:",
@@ -729,6 +739,7 @@ - (id)mgl_jsonExpressionObject {
             @"uppercase:": @"upcase",
             @"lowercase:": @"downcase",
             @"length:": @"length",
+            @"mgl_round:": @"round",
             // Vararg aftermarket expressions need to be declared with an explicit and implicit first argument.
             @"MGL_LET": @"let",
             @"MGL_LET:": @"let",

platform/darwin/test/MGLExpressionTests.mm

@@ -463,6 +463,30 @@ - (void)testArithmeticExpressionObject {
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @-2);
     }
+    {
+        NSExpression *expression = [NSExpression expressionForFunction:@"mgl_round:" arguments:@[MGLConstantExpression(@1.5)]];
+        NSArray *jsonExpression = @[@"round", @1.5];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @2);
+    }
+    {
+        NSExpression *expression = [NSExpression expressionForFunction:@"mgl_round:" arguments:@[MGLConstantExpression(@-1.5)]];
+        NSArray *jsonExpression = @[@"round", @-1.5];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @-2);
+    }
+    {
+        NSExpression *expression = [NSExpression expressionForFunction:@"mgl_round:" arguments:@[MGLConstantExpression(@2.5)]];
+        NSArray *jsonExpression = @[@"round", @2.5];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @3);
+    }
+    {
+        NSExpression *expression = [NSExpression expressionForFunction:@"mgl_round:" arguments:@[MGLConstantExpression(@-2.5)]];
+        NSArray *jsonExpression = @[@"round", @-2.5];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @-3);
+    }
 }
 
 - (void)testTrigonometricExpressionObject {

platform/ios/docs/guides/For Style Authors.md

@@ -379,7 +379,7 @@ In style specification | Method, function, or predicate type | Format string syn
 `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`                | |
+`round`                | `mgl_round:` | `mgl_round(1.5)`
 `sin`                  | |
 `sqrt`                 | `sqrt:` | `sqrt(2)`
 `tan`                  | |

platform/macos/docs/guides/For Style Authors.md

@@ -372,7 +372,7 @@ In style specification | Method, function, or predicate type | Format string syn
 `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`                | |
+`round`                | `mgl_round:` | `mgl_round(1.5)`
 `sin`                  | |
 `sqrt`                 | `sqrt:` | `sqrt(2)`
 `tan`                  | |