[core] Add DDS support for {text,icon}-size (#8593)

* Update gl-js and generate style code

* Factor out packUint8Pair() helper function

* Draft implementation of DDS for {text,icon}-size

Ports https://github.com/mapbox/mapbox-gl-js/pull/4455

* Fix text-size/composite-function-line-placement test

* Refactor to PaintPropertyBinders-like strategy

* Dedupe gl::Program construction

* Use exponential function base for interpolation

* Dedupe coveringZoomStops method

* Fixup tests

* Fix CI errors (hidden within #if block)

5 files changed, 294 insertions, 24 deletions

diff --git a/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/style/layers/PropertyFactory.java b/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/style/layers/PropertyFactory.java
index 269a777050..e37245000e 100644
--- a/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/style/layers/PropertyFactory.java
+++ b/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/style/layers/PropertyFactory.java
@@ -1526,11 +1526,11 @@ public class PropertyFactory {
   /**
    * Scale factor for icon. 1 is original size, 3 triples the size.
    *
-   * @param <Z> the zoom parameter type
-   * @param function a wrapper {@link CameraFunction} for Float
+   * @param <T> the function input type
+   * @param function a wrapper function for Float
    * @return property wrapper around a Float function
    */
-  public static <Z extends Number> PropertyValue<CameraFunction<Z, Float>> iconSize(CameraFunction<Z, Float> function) {
+  public static <T> PropertyValue<Function<T, Float>> iconSize(Function<T, Float> function) {
     return new LayoutPropertyValue<>("icon-size", function);
   }
 
@@ -1802,11 +1802,11 @@ public class PropertyFactory {
   /**
    * Font size.
    *
-   * @param <Z> the zoom parameter type
-   * @param function a wrapper {@link CameraFunction} for Float
+   * @param <T> the function input type
+   * @param function a wrapper function for Float
    * @return property wrapper around a Float function
    */
-  public static <Z extends Number> PropertyValue<CameraFunction<Z, Float>> textSize(CameraFunction<Z, Float> function) {
+  public static <T> PropertyValue<Function<T, Float>> textSize(Function<T, Float> function) {
     return new LayoutPropertyValue<>("text-size", function);
   }
 
diff --git a/platform/android/MapboxGLAndroidSDKTestApp/src/androidTest/java/com/mapbox/mapboxsdk/testapp/style/SymbolLayerTest.java b/platform/android/MapboxGLAndroidSDKTestApp/src/androidTest/java/com/mapbox/mapboxsdk/testapp/style/SymbolLayerTest.java
index e8af375d66..d81965f2c9 100644
--- a/platform/android/MapboxGLAndroidSDKTestApp/src/androidTest/java/com/mapbox/mapboxsdk/testapp/style/SymbolLayerTest.java
+++ b/platform/android/MapboxGLAndroidSDKTestApp/src/androidTest/java/com/mapbox/mapboxsdk/testapp/style/SymbolLayerTest.java
@@ -383,6 +383,114 @@ public class SymbolLayerTest extends BaseStyleTest {
 
 
   @Test
+  public void testIconSizeAsIdentitySourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-size");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconSize(property("FeaturePropertyA", Stops.<Float>identity()))
+    );
+
+    // Verify
+    assertNotNull(layer.getIconSize());
+    assertNotNull(layer.getIconSize().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconSize().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconSize().getFunction()).getProperty());
+    assertEquals(IdentityStops.class, layer.getIconSize().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testIconSizeAsExponentialSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-size");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconSize(
+        property(
+          "FeaturePropertyA",
+          exponential(
+            stop(0.3f, iconSize(0.3f))
+          ).withBase(0.5f)
+        )
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getIconSize());
+    assertNotNull(layer.getIconSize().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconSize().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconSize().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getIconSize().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testIconSizeAsCategoricalSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-size");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconSize(
+        property(
+          "FeaturePropertyA",
+          categorical(
+            stop(1.0f, iconSize(0.3f))
+          )
+        ).withDefaultValue(iconSize(0.3f))
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getIconSize());
+    assertNotNull(layer.getIconSize().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconSize().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconSize().getFunction()).getProperty());
+    assertEquals(CategoricalStops.class, layer.getIconSize().getFunction().getStops().getClass());
+    assertNotNull(((SourceFunction) layer.getIconSize().getFunction()).getDefaultValue());
+    assertNotNull(((SourceFunction) layer.getIconSize().getFunction()).getDefaultValue().getValue());
+    assertEquals(0.3f, ((SourceFunction) layer.getIconSize().getFunction()).getDefaultValue().getValue());
+  }
+
+  @Test
+  public void testIconSizeAsCompositeFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-size");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconSize(
+        composite(
+          "FeaturePropertyA",
+          exponential(
+            stop(0, 0.3f, iconSize(0.9f))
+          ).withBase(0.5f)
+        ).withDefaultValue(iconSize(0.3f))
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getIconSize());
+    assertNotNull(layer.getIconSize().getFunction());
+    assertEquals(CompositeFunction.class, layer.getIconSize().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((CompositeFunction) layer.getIconSize().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getIconSize().getFunction().getStops().getClass());
+    assertEquals(1, ((ExponentialStops) layer.getIconSize().getFunction().getStops()).size());
+
+    ExponentialStops<Stop.CompositeValue<Float, Float>, Float> stops =
+      (ExponentialStops<Stop.CompositeValue<Float, Float>, Float>) layer.getIconSize().getFunction().getStops();
+    Stop<Stop.CompositeValue<Float, Float>, Float> stop = stops.iterator().next();
+    assertEquals(0f, stop.in.zoom, 0.001);
+    assertEquals(0.3f, stop.in.value, 0.001f);
+    assertEquals(0.9f, stop.out, 0.001f);
+  }
+
+  @Test
   public void testIconTextFitAsConstant() {
     checkViewIsDisplayed(R.id.mapView);
     Timber.i("icon-text-fit");
@@ -1075,6 +1183,114 @@ public class SymbolLayerTest extends BaseStyleTest {
 
 
   @Test
+  public void testTextSizeAsIdentitySourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-size");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textSize(property("FeaturePropertyA", Stops.<Float>identity()))
+    );
+
+    // Verify
+    assertNotNull(layer.getTextSize());
+    assertNotNull(layer.getTextSize().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextSize().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextSize().getFunction()).getProperty());
+    assertEquals(IdentityStops.class, layer.getTextSize().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testTextSizeAsExponentialSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-size");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textSize(
+        property(
+          "FeaturePropertyA",
+          exponential(
+            stop(0.3f, textSize(0.3f))
+          ).withBase(0.5f)
+        )
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getTextSize());
+    assertNotNull(layer.getTextSize().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextSize().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextSize().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getTextSize().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testTextSizeAsCategoricalSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-size");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textSize(
+        property(
+          "FeaturePropertyA",
+          categorical(
+            stop(1.0f, textSize(0.3f))
+          )
+        ).withDefaultValue(textSize(0.3f))
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getTextSize());
+    assertNotNull(layer.getTextSize().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextSize().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextSize().getFunction()).getProperty());
+    assertEquals(CategoricalStops.class, layer.getTextSize().getFunction().getStops().getClass());
+    assertNotNull(((SourceFunction) layer.getTextSize().getFunction()).getDefaultValue());
+    assertNotNull(((SourceFunction) layer.getTextSize().getFunction()).getDefaultValue().getValue());
+    assertEquals(0.3f, ((SourceFunction) layer.getTextSize().getFunction()).getDefaultValue().getValue());
+  }
+
+  @Test
+  public void testTextSizeAsCompositeFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-size");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textSize(
+        composite(
+          "FeaturePropertyA",
+          exponential(
+            stop(0, 0.3f, textSize(0.9f))
+          ).withBase(0.5f)
+        ).withDefaultValue(textSize(0.3f))
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getTextSize());
+    assertNotNull(layer.getTextSize().getFunction());
+    assertEquals(CompositeFunction.class, layer.getTextSize().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((CompositeFunction) layer.getTextSize().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getTextSize().getFunction().getStops().getClass());
+    assertEquals(1, ((ExponentialStops) layer.getTextSize().getFunction().getStops()).size());
+
+    ExponentialStops<Stop.CompositeValue<Float, Float>, Float> stops =
+      (ExponentialStops<Stop.CompositeValue<Float, Float>, Float>) layer.getTextSize().getFunction().getStops();
+    Stop<Stop.CompositeValue<Float, Float>, Float> stop = stops.iterator().next();
+    assertEquals(0f, stop.in.zoom, 0.001);
+    assertEquals(0.3f, stop.in.value, 0.001f);
+    assertEquals(0.9f, stop.out, 0.001f);
+  }
+
+  @Test
   public void testTextMaxWidthAsConstant() {
     checkViewIsDisplayed(R.id.mapView);
     Timber.i("text-max-width");
diff --git a/platform/darwin/src/MGLSymbolStyleLayer.h b/platform/darwin/src/MGLSymbolStyleLayer.h
index 2c32b36c31..7040610093 100644
--- a/platform/darwin/src/MGLSymbolStyleLayer.h
+++ b/platform/darwin/src/MGLSymbolStyleLayer.h
@@ -537,6 +537,15 @@ MGL_EXPORT
  * `MGLCameraStyleFunction` with an interpolation mode of:
    * `MGLInterpolationModeExponential`
    * `MGLInterpolationModeInterval`
+ * `MGLSourceStyleFunction` with an interpolation mode of:
+   * `MGLInterpolationModeExponential`
+   * `MGLInterpolationModeInterval`
+   * `MGLInterpolationModeCategorical`
+   * `MGLInterpolationModeIdentity`
+ * `MGLCompositeStyleFunction` with an interpolation mode of:
+   * `MGLInterpolationModeExponential`
+   * `MGLInterpolationModeInterval`
+   * `MGLInterpolationModeCategorical`
  */
 @property (nonatomic, null_resettable) MGLStyleValue<NSNumber *> *iconScale;
 
@@ -919,6 +928,15 @@ MGL_EXPORT
  * `MGLCameraStyleFunction` with an interpolation mode of:
    * `MGLInterpolationModeExponential`
    * `MGLInterpolationModeInterval`
+ * `MGLSourceStyleFunction` with an interpolation mode of:
+   * `MGLInterpolationModeExponential`
+   * `MGLInterpolationModeInterval`
+   * `MGLInterpolationModeCategorical`
+   * `MGLInterpolationModeIdentity`
+ * `MGLCompositeStyleFunction` with an interpolation mode of:
+   * `MGLInterpolationModeExponential`
+   * `MGLInterpolationModeInterval`
+   * `MGLInterpolationModeCategorical`
  */
 @property (nonatomic, null_resettable) MGLStyleValue<NSNumber *> *textFontSize;
 
diff --git a/platform/darwin/src/MGLSymbolStyleLayer.mm b/platform/darwin/src/MGLSymbolStyleLayer.mm
index c01877f8dc..0f7953311e 100644
--- a/platform/darwin/src/MGLSymbolStyleLayer.mm
+++ b/platform/darwin/src/MGLSymbolStyleLayer.mm
@@ -356,7 +356,7 @@ namespace mbgl {
 - (void)setIconScale:(MGLStyleValue<NSNumber *> *)iconScale {
     MGLAssertStyleLayerIsValid();
 
-    auto mbglValue = MGLStyleValueTransformer<float, NSNumber *>().toInterpolatablePropertyValue(iconScale);
+    auto mbglValue = MGLStyleValueTransformer<float, NSNumber *>().toDataDrivenPropertyValue(iconScale);
     self.rawLayer->setIconSize(mbglValue);
 }
 
@@ -365,9 +365,9 @@ namespace mbgl {
 
     auto propertyValue = self.rawLayer->getIconSize();
     if (propertyValue.isUndefined()) {
-        return MGLStyleValueTransformer<float, NSNumber *>().toStyleValue(self.rawLayer->getDefaultIconSize());
+        return MGLStyleValueTransformer<float, NSNumber *>().toDataDrivenStyleValue(self.rawLayer->getDefaultIconSize());
     }
-    return MGLStyleValueTransformer<float, NSNumber *>().toStyleValue(propertyValue);
+    return MGLStyleValueTransformer<float, NSNumber *>().toDataDrivenStyleValue(propertyValue);
 }
 
 - (void)setIconSize:(MGLStyleValue<NSNumber *> *)iconSize {
@@ -657,7 +657,7 @@ namespace mbgl {
 - (void)setTextFontSize:(MGLStyleValue<NSNumber *> *)textFontSize {
     MGLAssertStyleLayerIsValid();
 
-    auto mbglValue = MGLStyleValueTransformer<float, NSNumber *>().toInterpolatablePropertyValue(textFontSize);
+    auto mbglValue = MGLStyleValueTransformer<float, NSNumber *>().toDataDrivenPropertyValue(textFontSize);
     self.rawLayer->setTextSize(mbglValue);
 }
 
@@ -666,9 +666,9 @@ namespace mbgl {
 
     auto propertyValue = self.rawLayer->getTextSize();
     if (propertyValue.isUndefined()) {
-        return MGLStyleValueTransformer<float, NSNumber *>().toStyleValue(self.rawLayer->getDefaultTextSize());
+        return MGLStyleValueTransformer<float, NSNumber *>().toDataDrivenStyleValue(self.rawLayer->getDefaultTextSize());
     }
-    return MGLStyleValueTransformer<float, NSNumber *>().toStyleValue(propertyValue);
+    return MGLStyleValueTransformer<float, NSNumber *>().toDataDrivenStyleValue(propertyValue);
 }
 
 - (void)setTextSize:(MGLStyleValue<NSNumber *> *)textSize {
diff --git a/platform/darwin/test/MGLSymbolStyleLayerTests.mm b/platform/darwin/test/MGLSymbolStyleLayerTests.mm
index eee61dd5d7..367ebf363c 100644
--- a/platform/darwin/test/MGLSymbolStyleLayerTests.mm
+++ b/platform/darwin/test/MGLSymbolStyleLayerTests.mm
@@ -405,7 +405,7 @@
 
         MGLStyleValue<NSNumber *> *constantStyleValue = [MGLStyleValue<NSNumber *> valueWithRawValue:@0xff];
         layer.iconScale = constantStyleValue;
-        mbgl::style::PropertyValue<float> propertyValue = { 0xff };
+        mbgl::style::DataDrivenPropertyValue<float> propertyValue = { 0xff };
         XCTAssertEqual(rawLayer->getIconSize(), propertyValue,
                        @"Setting iconScale to a constant value should update icon-size.");
         XCTAssertEqualObjects(layer.iconScale, constantStyleValue,
@@ -422,6 +422,29 @@
         XCTAssertEqualObjects(layer.iconScale, functionStyleValue,
                               @"iconScale should round-trip camera functions.");
 
+        functionStyleValue = [MGLStyleValue<NSNumber *> valueWithInterpolationMode:MGLInterpolationModeExponential sourceStops:@{@18: constantStyleValue} attributeName:@"keyName" options:nil];
+        layer.iconScale = functionStyleValue;
+
+        mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
+        propertyValue = mbgl::style::SourceFunction<float> { "keyName", exponentialStops };
+
+        XCTAssertEqual(rawLayer->getIconSize(), propertyValue,
+                       @"Setting iconScale to a source function should update icon-size.");
+        XCTAssertEqualObjects(layer.iconScale, functionStyleValue,
+                              @"iconScale should round-trip source functions.");
+
+        functionStyleValue = [MGLStyleValue<NSNumber *> valueWithInterpolationMode:MGLInterpolationModeExponential compositeStops:@{@10: @{@18: constantStyleValue}} attributeName:@"keyName" options:nil];
+        layer.iconScale = functionStyleValue;
+
+        std::map<float, float> innerStops { {18, 0xff} };
+        mbgl::style::CompositeExponentialStops<float> compositeStops { { {10.0, innerStops} }, 1.0 };
+
+        propertyValue = mbgl::style::CompositeFunction<float> { "keyName", compositeStops };
+
+        XCTAssertEqual(rawLayer->getIconSize(), propertyValue,
+                       @"Setting iconScale to a composite function should update icon-size.");
+        XCTAssertEqualObjects(layer.iconScale, functionStyleValue,
+                              @"iconScale should round-trip composite functions.");                                                                                                          
                               
 
         layer.iconScale = nil;
@@ -429,11 +452,6 @@
                       @"Unsetting iconScale should return icon-size to the default value.");
         XCTAssertEqualObjects(layer.iconScale, defaultStyleValue,
                               @"iconScale should return the default value after being unset.");
-
-        functionStyleValue = [MGLStyleValue<NSNumber *> valueWithInterpolationMode:MGLInterpolationModeIdentity sourceStops:nil attributeName:@"" options:nil];
-        XCTAssertThrowsSpecificNamed(layer.iconScale = functionStyleValue, NSException, NSInvalidArgumentException, @"MGLStyleValue should raise an exception if it is applied to a property that cannot support it");
-        functionStyleValue = [MGLStyleValue<NSNumber *> valueWithInterpolationMode:MGLInterpolationModeInterval compositeStops:@{@18: constantStyleValue} attributeName:@"" options:nil];
-        XCTAssertThrowsSpecificNamed(layer.iconScale = functionStyleValue, NSException, NSInvalidArgumentException, @"MGLStyleValue should raise an exception if it is applied to a property that cannot support it");
     }
 
     // icon-text-fit
@@ -952,7 +970,7 @@
 
         MGLStyleValue<NSNumber *> *constantStyleValue = [MGLStyleValue<NSNumber *> valueWithRawValue:@0xff];
         layer.textFontSize = constantStyleValue;
-        mbgl::style::PropertyValue<float> propertyValue = { 0xff };
+        mbgl::style::DataDrivenPropertyValue<float> propertyValue = { 0xff };
         XCTAssertEqual(rawLayer->getTextSize(), propertyValue,
                        @"Setting textFontSize to a constant value should update text-size.");
         XCTAssertEqualObjects(layer.textFontSize, constantStyleValue,
@@ -969,6 +987,29 @@
         XCTAssertEqualObjects(layer.textFontSize, functionStyleValue,
                               @"textFontSize should round-trip camera functions.");
 
+        functionStyleValue = [MGLStyleValue<NSNumber *> valueWithInterpolationMode:MGLInterpolationModeExponential sourceStops:@{@18: constantStyleValue} attributeName:@"keyName" options:nil];
+        layer.textFontSize = functionStyleValue;
+
+        mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
+        propertyValue = mbgl::style::SourceFunction<float> { "keyName", exponentialStops };
+
+        XCTAssertEqual(rawLayer->getTextSize(), propertyValue,
+                       @"Setting textFontSize to a source function should update text-size.");
+        XCTAssertEqualObjects(layer.textFontSize, functionStyleValue,
+                              @"textFontSize should round-trip source functions.");
+
+        functionStyleValue = [MGLStyleValue<NSNumber *> valueWithInterpolationMode:MGLInterpolationModeExponential compositeStops:@{@10: @{@18: constantStyleValue}} attributeName:@"keyName" options:nil];
+        layer.textFontSize = functionStyleValue;
+
+        std::map<float, float> innerStops { {18, 0xff} };
+        mbgl::style::CompositeExponentialStops<float> compositeStops { { {10.0, innerStops} }, 1.0 };
+
+        propertyValue = mbgl::style::CompositeFunction<float> { "keyName", compositeStops };
+
+        XCTAssertEqual(rawLayer->getTextSize(), propertyValue,
+                       @"Setting textFontSize to a composite function should update text-size.");
+        XCTAssertEqualObjects(layer.textFontSize, functionStyleValue,
+                              @"textFontSize should round-trip composite functions.");                                                                                                          
                               
 
         layer.textFontSize = nil;
@@ -976,11 +1017,6 @@
                       @"Unsetting textFontSize should return text-size to the default value.");
         XCTAssertEqualObjects(layer.textFontSize, defaultStyleValue,
                               @"textFontSize should return the default value after being unset.");
-
-        functionStyleValue = [MGLStyleValue<NSNumber *> valueWithInterpolationMode:MGLInterpolationModeIdentity sourceStops:nil attributeName:@"" options:nil];
-        XCTAssertThrowsSpecificNamed(layer.textFontSize = functionStyleValue, NSException, NSInvalidArgumentException, @"MGLStyleValue should raise an exception if it is applied to a property that cannot support it");
-        functionStyleValue = [MGLStyleValue<NSNumber *> valueWithInterpolationMode:MGLInterpolationModeInterval compositeStops:@{@18: constantStyleValue} attributeName:@"" options:nil];
-        XCTAssertThrowsSpecificNamed(layer.textFontSize = functionStyleValue, NSException, NSInvalidArgumentException, @"MGLStyleValue should raise an exception if it is applied to a property that cannot support it");
     }
 
     // text-ignore-placement