[ios, macos] Minimal darwin wrappers of 'format' expression

Add support for `MGL_FUNCTION('format', <text>, <options dictionary>)`

8 files changed, 67 insertions, 14 deletions

diff --git a/include/mbgl/style/expression/dsl.hpp b/include/mbgl/style/expression/dsl.hpp
index a4483a6fe6..bd94a765e7 100644
--- a/include/mbgl/style/expression/dsl.hpp
+++ b/include/mbgl/style/expression/dsl.hpp
@@ -38,7 +38,8 @@ std::unique_ptr<Expression> boolean(std::unique_ptr<Expression>);
 
 std::unique_ptr<Expression> toColor(std::unique_ptr<Expression>);
 std::unique_ptr<Expression> toString(std::unique_ptr<Expression>);
-
+std::unique_ptr<Expression> toFormatted(std::unique_ptr<Expression>);
+    
 std::unique_ptr<Expression> get(const char* value);
 std::unique_ptr<Expression> get(std::unique_ptr<Expression>);
 
@@ -78,6 +79,9 @@ std::unique_ptr<Expression> interpolate(Interpolator interpolator,
                                         double input3, std::unique_ptr<Expression> output3);
 
 std::unique_ptr<Expression> concat(std::vector<std::unique_ptr<Expression>> inputs);
+    
+std::unique_ptr<Expression> format(const char* value);
+std::unique_ptr<Expression> format(std::unique_ptr<Expression>);
 
 } // namespace dsl
 } // namespace expression
diff --git a/platform/darwin/scripts/generate-style-code.js b/platform/darwin/scripts/generate-style-code.js
index bc676e9cba..c4c28c7946 100755
--- a/platform/darwin/scripts/generate-style-code.js
+++ b/platform/darwin/scripts/generate-style-code.js
@@ -103,6 +103,11 @@ global.objCTestValue = function (property, layerType, arraysAsStructs, indent) {
         case 'number':
             return '@"1"';
         case 'formatted':
+            // Special 'string' case to handle constant expression text-field that automatically
+            // converts Formatted back to string.
+            return layerType === 'string' ?
+                `@"'${_.startCase(propertyName)}'"` :
+                `@"MGL_FUNCTION('format', '${_.startCase(propertyName)}', %@)", @{}`;
         case 'string':
             return `@"'${_.startCase(propertyName)}'"`;
         case 'enum':
@@ -559,6 +564,7 @@ global.valueTransformerArguments = function (property) {
         case 'number':
             return ['float', objCType];
         case 'formatted':
+            return ['mbgl::style::expression::Formatted', objCType];
         case 'string':
             return ['std::string', objCType];
         case 'enum':
@@ -593,6 +599,7 @@ global.mbglType = function(property) {
         case 'number':
             return 'float';
         case 'formatted':
+            return 'mbgl::style::expression::Formatted';
         case 'string':
             return 'std::string';
         case 'enum': {
diff --git a/platform/darwin/src/MGLStyleLayer.mm.ejs b/platform/darwin/src/MGLStyleLayer.mm.ejs
index 49ac04ce05..6d0c4bfdd9 100644
--- a/platform/darwin/src/MGLStyleLayer.mm.ejs
+++ b/platform/darwin/src/MGLStyleLayer.mm.ejs
@@ -125,8 +125,13 @@ namespace mbgl {
     if (<%- objCName(property) %> && <%- objCName(property) %>.expressionType == NSConstantValueExpressionType) {
         std::string string = ((NSString *)<%- objCName(property) %>.constantValue).UTF8String;
         if (mbgl::style::conversion::hasTokens(string)) {
+<% if (property.type === 'formatted') { -%>
+            self.rawLayer->set<%- camelize(originalPropertyName(property)) %>(mbgl::style::PropertyValue<mbgl::style::expression::Formatted>(
+                mbgl::style::conversion::convertTokenStringToFormatExpression(string)));
+<% } else { -%>
             self.rawLayer->set<%- camelize(originalPropertyName(property)) %>(mbgl::style::PropertyValue<std::string>(
                 mbgl::style::conversion::convertTokenStringToExpression(string)));
+<% } -%>
             return;
         }
     }
diff --git a/platform/darwin/src/MGLStyleValue_Private.h b/platform/darwin/src/MGLStyleValue_Private.h
index 75e422fb45..cc1950bfb8 100644
--- a/platform/darwin/src/MGLStyleValue_Private.h
+++ b/platform/darwin/src/MGLStyleValue_Private.h
@@ -162,6 +162,11 @@ private: // Private utilities for converting from mgl to mbgl values
         mbglValue = rawValue.UTF8String;
     }
 
+    // Formatted
+    void getMBGLValue(NSString *rawValue, mbgl::style::expression::Formatted &mbglValue) {
+        mbglValue = mbgl::style::expression::Formatted(rawValue.UTF8String);
+    }
+
     // Offsets
     void getMBGLValue(id rawValue, std::array<float, 2> &mbglValue) {
         if ([rawValue isKindOfClass:[NSValue class]]) {
@@ -250,6 +255,11 @@ private: // Private utilities for converting from mbgl to mgl values
         return @(mbglStopValue.c_str());
     }
 
+    // Formatted
+    static NSString *toMGLRawStyleValue(const mbgl::style::expression::Formatted &mbglStopValue) {
+        return @(mbglStopValue.toString().c_str());
+    }
+
     // Offsets
     static NSValue *toMGLRawStyleValue(const std::array<float, 2> &mbglStopValue) {
         return [NSValue mgl_valueWithOffsetArray:mbglStopValue];
diff --git a/platform/darwin/src/MGLSymbolStyleLayer.mm b/platform/darwin/src/MGLSymbolStyleLayer.mm
index 4c0fcfe539..e1bc7e7d20 100644
--- a/platform/darwin/src/MGLSymbolStyleLayer.mm
+++ b/platform/darwin/src/MGLSymbolStyleLayer.mm
@@ -601,12 +601,12 @@ namespace mbgl {
     if (text && text.expressionType == NSConstantValueExpressionType) {
         std::string string = ((NSString *)text.constantValue).UTF8String;
         if (mbgl::style::conversion::hasTokens(string)) {
-            self.rawLayer->setTextField(mbgl::style::PropertyValue<std::string>(
-                mbgl::style::conversion::convertTokenStringToExpression(string)));
+            self.rawLayer->setTextField(mbgl::style::PropertyValue<mbgl::style::expression::Formatted>(
+                mbgl::style::conversion::convertTokenStringToFormatExpression(string)));
             return;
         }
     }
-    auto mbglValue = MGLStyleValueTransformer<std::string, NSString *>().toPropertyValue<mbgl::style::PropertyValue<std::string>>(text, true);
+    auto mbglValue = MGLStyleValueTransformer<mbgl::style::expression::Formatted, NSString *>().toPropertyValue<mbgl::style::PropertyValue<mbgl::style::expression::Formatted>>(text, true);
     self.rawLayer->setTextField(mbglValue);
 }
 
@@ -617,7 +617,7 @@ namespace mbgl {
     if (propertyValue.isUndefined()) {
         propertyValue = self.rawLayer->getDefaultTextField();
     }
-    return MGLStyleValueTransformer<std::string, NSString *>().toExpression(propertyValue);
+    return MGLStyleValueTransformer<mbgl::style::expression::Formatted, NSString *>().toExpression(propertyValue);
 }
 
 - (void)setTextField:(NSExpression *)textField {
diff --git a/platform/darwin/src/NSExpression+MGLAdditions.mm b/platform/darwin/src/NSExpression+MGLAdditions.mm
index 58f5816416..1a8dff060c 100644
--- a/platform/darwin/src/NSExpression+MGLAdditions.mm
+++ b/platform/darwin/src/NSExpression+MGLAdditions.mm
@@ -1111,6 +1111,11 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
                     // Avoid wrapping collator options object in literal expression.
                     return @[@"collator", self.arguments[1].constantValue];
                 }
+                if (op.expressionType == NSConstantValueExpressionType
+                    && [op.constantValue isEqualToString:@"format"]) {
+                    // Avoid wrapping format options object in literal expression.
+                    return @[@"format", self.arguments[1].mgl_jsonExpressionObject, self.arguments[2].constantValue];
+                }
                 return self.arguments.mgl_jsonExpressionObject;
             } else if (op == [MGLColor class] && [function isEqualToString:@"colorWithRed:green:blue:alpha:"]) {
                 NSArray *arguments = self.arguments.mgl_jsonExpressionObject;
diff --git a/platform/darwin/test/MGLStyleLayerTests.mm.ejs b/platform/darwin/test/MGLStyleLayerTests.mm.ejs
index 89b6cbe7e4..c97813eca2 100644
--- a/platform/darwin/test/MGLStyleLayerTests.mm.ejs
+++ b/platform/darwin/test/MGLStyleLayerTests.mm.ejs
@@ -68,7 +68,11 @@
                       @"<%- originalPropertyName(property) %> should be unset initially.");
         NSExpression *defaultExpression = layer.<%- objCName(property) %>;
 
+<% if (property.type === 'formatted') { -%>
+        NSExpression *constantExpression = [NSExpression expressionWithFormat:<%- objCTestValue(property, 'string', true, 3) %>];
+<% } else { -%>
         NSExpression *constantExpression = [NSExpression expressionWithFormat:<%- objCTestValue(property, type, true, 3) %>];
+<% } -%>
         layer.<%- objCName(property) %> = constantExpression;
         mbgl::style::PropertyValue<<%- mbglType(property) %>> propertyValue = { <%- mbglTestValue(property, type) %> };
         XCTAssertEqual(rawLayer->get<%- camelize(originalPropertyName(property)) %>(), propertyValue,
@@ -83,7 +87,11 @@
         {
             using namespace mbgl::style::expression::dsl;
             propertyValue = mbgl::style::PropertyExpression<<%- mbglType(property) %>>(
+<% if (property.type === 'formatted') { -%>
+                step(zoom(), format(<%- mbglExpressionTestValue(property, type) %>), 18.0, format(<%- mbglExpressionTestValue(property, type) %>))
+<% } else { -%>
                 step(zoom(), literal(<%- mbglExpressionTestValue(property, type) %>), 18.0, literal(<%- mbglExpressionTestValue(property, type) %>))
+<% } -%>
             );
         }
 
@@ -160,13 +168,23 @@
         {
             using namespace mbgl::style::expression::dsl;
             propertyValue = mbgl::style::PropertyExpression<<%- mbglType(property) %>>(
+<% if (property.type === 'formatted') { -%>
+                format(toString(get(literal("token"))))
+<% } else { -%>
                 toString(get(literal("token")))
+<% } -%>
             );
         }
 
         XCTAssertEqual(rawLayer->get<%- camelize(originalPropertyName(property)) %>(), propertyValue,
                        @"Setting <%- objCName(property) %> to a constant string with tokens should convert to an expression.");
-        XCTAssertEqualObjects(layer.<%- objCName(property) %>, [NSExpression expressionWithFormat:@"CAST(token, \"NSString\")"],
+
+<% if (property.type === 'formatted') { -%>
+        NSExpression* tokenExpression = [NSExpression expressionWithFormat:@"MGL_FUNCTION('format', CAST(token, 'NSString'), %@)", @{}];
+<% } else { -%>
+        NSExpression* tokenExpression = [NSExpression expressionWithFormat:@"CAST(token, \"NSString\")"];
+<% } -%>
+        XCTAssertEqualObjects(layer.<%- objCName(property) %>, tokenExpression,
                               @"Setting <%- objCName(property) %> to a constant string with tokens should convert to an expression.");
 <% } -%>
     }
diff --git a/platform/darwin/test/MGLSymbolStyleLayerTests.mm b/platform/darwin/test/MGLSymbolStyleLayerTests.mm
index 865de68933..42430940cd 100644
--- a/platform/darwin/test/MGLSymbolStyleLayerTests.mm
+++ b/platform/darwin/test/MGLSymbolStyleLayerTests.mm
@@ -224,7 +224,9 @@
 
         XCTAssertEqual(rawLayer->getIconImage(), propertyValue,
                        @"Setting iconImageName to a constant string with tokens should convert to an expression.");
-        XCTAssertEqualObjects(layer.iconImageName, [NSExpression expressionWithFormat:@"CAST(token, \"NSString\")"],
+
+        NSExpression* tokenExpression = [NSExpression expressionWithFormat:@"CAST(token, \"NSString\")"];
+        XCTAssertEqualObjects(layer.iconImageName, tokenExpression,
                               @"Setting iconImageName to a constant string with tokens should convert to an expression.");
     }
 
@@ -1096,20 +1098,20 @@
 
         NSExpression *constantExpression = [NSExpression expressionWithFormat:@"'Text Field'"];
         layer.text = constantExpression;
-        mbgl::style::PropertyValue<std::string> propertyValue = { "Text Field" };
+        mbgl::style::PropertyValue<mbgl::style::expression::Formatted> propertyValue = { "Text Field" };
         XCTAssertEqual(rawLayer->getTextField(), propertyValue,
                        @"Setting text to a constant value expression should update text-field.");
         XCTAssertEqualObjects(layer.text, constantExpression,
                               @"text should round-trip constant value expressions.");
 
-        constantExpression = [NSExpression expressionWithFormat:@"'Text Field'"];
+        constantExpression = [NSExpression expressionWithFormat:@"MGL_FUNCTION('format', 'Text Field', %@)", @{}];
         NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.text = functionExpression;
 
         {
             using namespace mbgl::style::expression::dsl;
-            propertyValue = mbgl::style::PropertyExpression<std::string>(
-                step(zoom(), literal("Text Field"), 18.0, literal("Text Field"))
+            propertyValue = mbgl::style::PropertyExpression<mbgl::style::expression::Formatted>(
+                step(zoom(), format("Text Field"), 18.0, format("Text Field"))
             );
         }
 
@@ -1130,14 +1132,16 @@
 
         {
             using namespace mbgl::style::expression::dsl;
-            propertyValue = mbgl::style::PropertyExpression<std::string>(
-                toString(get(literal("token")))
+            propertyValue = mbgl::style::PropertyExpression<mbgl::style::expression::Formatted>(
+                format(toString(get(literal("token"))))
             );
         }
 
         XCTAssertEqual(rawLayer->getTextField(), propertyValue,
                        @"Setting text to a constant string with tokens should convert to an expression.");
-        XCTAssertEqualObjects(layer.text, [NSExpression expressionWithFormat:@"CAST(token, \"NSString\")"],
+
+        NSExpression* tokenExpression = [NSExpression expressionWithFormat:@"MGL_FUNCTION('format', CAST(token, 'NSString'), %@)", @{}];
+        XCTAssertEqualObjects(layer.text, tokenExpression,
                               @"Setting text to a constant string with tokens should convert to an expression.");
     }