[core] Implement data-driven styling for {text,icon}-{color,opacity,halo-color,halo-blur,halo-width} (#7939)

* Add symbol dds attributes and adapt style code generation

* Update to mapbox-gl-js/master

* Refactor SymbolFeature as a subclass of GeometryTileFeature

Prepares for enabling DDS on symbol paint properties by allowing the
SymbolFeatures, which we keep around after constructing SymbolLayout,
to be used in evaluating data-driven paint properties later in the
layout process.

* Draft approach for splitting icon/text paint properties

The `Program` types are set up to bind GL attributes to each of the
data-driven paint properties specified in the `PaintProperties` type
provided.  Since `SymbolPaintProperties` specifies both `Text*` and
`Icon*` properties, the symbolIcon, symbolIconSDF, and symbolGlyph
programs each attempt to bind roughly double the number of attributes
that they actually need.

This change addresses this by:
- Adding the more specific `IconPaintProperties` and `TextPaintProperties` types, which are subsets of the full `SymbolPaintProperties`.
- The symbol layer continues to use its `SymbolPaintProperties paint` member to track layer property state, but it provides helpers that construct objects of each the specific `{Icon,Text}PaintProperties::Evaluated` type, for use by the painter.
- The three symbol programs instantiate `Program<>` using the appropriate `{Icon,Text}PaintProperties` type.

* check in generated style code

* Populate paint buffers for symbol DDS properties

* Address first round of review comments

* Refactor VectorTile{Layer,Feature} to explicitly share data

* Update submodule

1 files changed, 920 insertions, 0 deletions

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 74b9555183..3b3bc9c8b5 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
@@ -1598,6 +1598,112 @@ public class SymbolLayerTest extends BaseStyleTest {
   }
 
   @Test
+  public void testIconOpacityAsIdentitySourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-opacity");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconOpacity(property("FeaturePropertyA", Stops.<Float>identity()))
+    );
+
+    // Verify
+    assertNotNull(layer.getIconOpacity());
+    assertNotNull(layer.getIconOpacity().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconOpacity().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconOpacity().getFunction()).getProperty());
+    assertEquals(IdentityStops.class, layer.getIconOpacity().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testIconOpacityAsExponentialSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-opacity");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconOpacity(
+        property(
+          "FeaturePropertyA",
+          exponential(
+            stop(0.3f, iconOpacity(0.3f))
+          ).withBase(0.5f)
+        )
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getIconOpacity());
+    assertNotNull(layer.getIconOpacity().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconOpacity().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconOpacity().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getIconOpacity().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testIconOpacityAsCategoricalSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-opacity");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconOpacity(
+        property(
+          "FeaturePropertyA",
+          categorical(
+            stop(1.0f, iconOpacity(0.3f))
+          )
+        ).withDefaultValue(0.3f)
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getIconOpacity());
+    assertNotNull(layer.getIconOpacity().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconOpacity().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconOpacity().getFunction()).getProperty());
+    assertEquals(CategoricalStops.class, layer.getIconOpacity().getFunction().getStops().getClass());
+    assertEquals(0.3f, ((SourceFunction) layer.getIconOpacity().getFunction()).getDefaultValue());
+  }
+
+  @Test
+  public void testIconOpacityAsCompositeFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-opacity");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconOpacity(
+        composite(
+          "FeaturePropertyA",
+          exponential(
+            stop(0, 0.3f, iconOpacity(0.9f))
+          ).withBase(0.5f)
+        ).withDefaultValue(0.3f)
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getIconOpacity());
+    assertNotNull(layer.getIconOpacity().getFunction());
+    assertEquals(CompositeFunction.class, layer.getIconOpacity().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((CompositeFunction) layer.getIconOpacity().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getIconOpacity().getFunction().getStops().getClass());
+    assertEquals(1, ((ExponentialStops) layer.getIconOpacity().getFunction().getStops()).size());
+
+    ExponentialStops<Stop.CompositeValue<Float, Float>, Float> stops =
+      (ExponentialStops<Stop.CompositeValue<Float, Float>, Float>) layer.getIconOpacity().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 testIconColorAsConstant() {
     checkViewIsDisplayed(R.id.mapView);
     Timber.i("icon-color");
@@ -1635,6 +1741,77 @@ public class SymbolLayerTest extends BaseStyleTest {
   }
 
   @Test
+  public void testIconColorAsIdentitySourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-color");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconColor(property("FeaturePropertyA", Stops.<String>identity()))
+    );
+
+    // Verify
+    assertNotNull(layer.getIconColor());
+    assertNotNull(layer.getIconColor().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconColor().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconColor().getFunction()).getProperty());
+    assertEquals(IdentityStops.class, layer.getIconColor().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testIconColorAsExponentialSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-color");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconColor(
+        property(
+          "FeaturePropertyA",
+          exponential(
+            stop(Color.RED, iconColor(Color.RED))
+          ).withBase(0.5f)
+        )
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getIconColor());
+    assertNotNull(layer.getIconColor().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconColor().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconColor().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getIconColor().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testIconColorAsCategoricalSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-color");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconColor(
+        property(
+          "FeaturePropertyA",
+          categorical(
+            stop("valueA", iconColor(Color.RED))
+          )
+        )
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getIconColor());
+    assertNotNull(layer.getIconColor().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconColor().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconColor().getFunction()).getProperty());
+    assertEquals(CategoricalStops.class, layer.getIconColor().getFunction().getStops().getClass());
+  }
+
+  @Test
   public void testIconColorAsIntConstant() {
     checkViewIsDisplayed(R.id.mapView);
     Timber.i("icon-color");
@@ -1683,6 +1860,77 @@ public class SymbolLayerTest extends BaseStyleTest {
   }
 
   @Test
+  public void testIconHaloColorAsIdentitySourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-halo-color");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconHaloColor(property("FeaturePropertyA", Stops.<String>identity()))
+    );
+
+    // Verify
+    assertNotNull(layer.getIconHaloColor());
+    assertNotNull(layer.getIconHaloColor().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconHaloColor().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconHaloColor().getFunction()).getProperty());
+    assertEquals(IdentityStops.class, layer.getIconHaloColor().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testIconHaloColorAsExponentialSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-halo-color");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconHaloColor(
+        property(
+          "FeaturePropertyA",
+          exponential(
+            stop(Color.RED, iconHaloColor(Color.RED))
+          ).withBase(0.5f)
+        )
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getIconHaloColor());
+    assertNotNull(layer.getIconHaloColor().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconHaloColor().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconHaloColor().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getIconHaloColor().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testIconHaloColorAsCategoricalSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-halo-color");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconHaloColor(
+        property(
+          "FeaturePropertyA",
+          categorical(
+            stop("valueA", iconHaloColor(Color.RED))
+          )
+        )
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getIconHaloColor());
+    assertNotNull(layer.getIconHaloColor().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconHaloColor().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconHaloColor().getFunction()).getProperty());
+    assertEquals(CategoricalStops.class, layer.getIconHaloColor().getFunction().getStops().getClass());
+  }
+
+  @Test
   public void testIconHaloColorAsIntConstant() {
     checkViewIsDisplayed(R.id.mapView);
     Timber.i("icon-halo-color");
@@ -1731,6 +1979,112 @@ public class SymbolLayerTest extends BaseStyleTest {
   }
 
   @Test
+  public void testIconHaloWidthAsIdentitySourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-halo-width");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconHaloWidth(property("FeaturePropertyA", Stops.<Float>identity()))
+    );
+
+    // Verify
+    assertNotNull(layer.getIconHaloWidth());
+    assertNotNull(layer.getIconHaloWidth().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconHaloWidth().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconHaloWidth().getFunction()).getProperty());
+    assertEquals(IdentityStops.class, layer.getIconHaloWidth().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testIconHaloWidthAsExponentialSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-halo-width");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconHaloWidth(
+        property(
+          "FeaturePropertyA",
+          exponential(
+            stop(0.3f, iconHaloWidth(0.3f))
+          ).withBase(0.5f)
+        )
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getIconHaloWidth());
+    assertNotNull(layer.getIconHaloWidth().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconHaloWidth().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconHaloWidth().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getIconHaloWidth().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testIconHaloWidthAsCategoricalSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-halo-width");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconHaloWidth(
+        property(
+          "FeaturePropertyA",
+          categorical(
+            stop(1.0f, iconHaloWidth(0.3f))
+          )
+        ).withDefaultValue(0.3f)
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getIconHaloWidth());
+    assertNotNull(layer.getIconHaloWidth().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconHaloWidth().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconHaloWidth().getFunction()).getProperty());
+    assertEquals(CategoricalStops.class, layer.getIconHaloWidth().getFunction().getStops().getClass());
+    assertEquals(0.3f, ((SourceFunction) layer.getIconHaloWidth().getFunction()).getDefaultValue());
+  }
+
+  @Test
+  public void testIconHaloWidthAsCompositeFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-halo-width");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconHaloWidth(
+        composite(
+          "FeaturePropertyA",
+          exponential(
+            stop(0, 0.3f, iconHaloWidth(0.9f))
+          ).withBase(0.5f)
+        ).withDefaultValue(0.3f)
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getIconHaloWidth());
+    assertNotNull(layer.getIconHaloWidth().getFunction());
+    assertEquals(CompositeFunction.class, layer.getIconHaloWidth().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((CompositeFunction) layer.getIconHaloWidth().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getIconHaloWidth().getFunction().getStops().getClass());
+    assertEquals(1, ((ExponentialStops) layer.getIconHaloWidth().getFunction().getStops()).size());
+
+    ExponentialStops<Stop.CompositeValue<Float, Float>, Float> stops =
+      (ExponentialStops<Stop.CompositeValue<Float, Float>, Float>) layer.getIconHaloWidth().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 testIconHaloBlurAsConstant() {
     checkViewIsDisplayed(R.id.mapView);
     Timber.i("icon-halo-blur");
@@ -1768,6 +2122,112 @@ public class SymbolLayerTest extends BaseStyleTest {
   }
 
   @Test
+  public void testIconHaloBlurAsIdentitySourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-halo-blur");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconHaloBlur(property("FeaturePropertyA", Stops.<Float>identity()))
+    );
+
+    // Verify
+    assertNotNull(layer.getIconHaloBlur());
+    assertNotNull(layer.getIconHaloBlur().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconHaloBlur().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconHaloBlur().getFunction()).getProperty());
+    assertEquals(IdentityStops.class, layer.getIconHaloBlur().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testIconHaloBlurAsExponentialSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-halo-blur");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconHaloBlur(
+        property(
+          "FeaturePropertyA",
+          exponential(
+            stop(0.3f, iconHaloBlur(0.3f))
+          ).withBase(0.5f)
+        )
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getIconHaloBlur());
+    assertNotNull(layer.getIconHaloBlur().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconHaloBlur().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconHaloBlur().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getIconHaloBlur().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testIconHaloBlurAsCategoricalSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-halo-blur");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconHaloBlur(
+        property(
+          "FeaturePropertyA",
+          categorical(
+            stop(1.0f, iconHaloBlur(0.3f))
+          )
+        ).withDefaultValue(0.3f)
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getIconHaloBlur());
+    assertNotNull(layer.getIconHaloBlur().getFunction());
+    assertEquals(SourceFunction.class, layer.getIconHaloBlur().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getIconHaloBlur().getFunction()).getProperty());
+    assertEquals(CategoricalStops.class, layer.getIconHaloBlur().getFunction().getStops().getClass());
+    assertEquals(0.3f, ((SourceFunction) layer.getIconHaloBlur().getFunction()).getDefaultValue());
+  }
+
+  @Test
+  public void testIconHaloBlurAsCompositeFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("icon-halo-blur");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      iconHaloBlur(
+        composite(
+          "FeaturePropertyA",
+          exponential(
+            stop(0, 0.3f, iconHaloBlur(0.9f))
+          ).withBase(0.5f)
+        ).withDefaultValue(0.3f)
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getIconHaloBlur());
+    assertNotNull(layer.getIconHaloBlur().getFunction());
+    assertEquals(CompositeFunction.class, layer.getIconHaloBlur().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((CompositeFunction) layer.getIconHaloBlur().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getIconHaloBlur().getFunction().getStops().getClass());
+    assertEquals(1, ((ExponentialStops) layer.getIconHaloBlur().getFunction().getStops()).size());
+
+    ExponentialStops<Stop.CompositeValue<Float, Float>, Float> stops =
+      (ExponentialStops<Stop.CompositeValue<Float, Float>, Float>) layer.getIconHaloBlur().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 testIconTranslateAsConstant() {
     checkViewIsDisplayed(R.id.mapView);
     Timber.i("icon-translate");
@@ -1878,6 +2338,112 @@ public class SymbolLayerTest extends BaseStyleTest {
   }
 
   @Test
+  public void testTextOpacityAsIdentitySourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-opacity");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textOpacity(property("FeaturePropertyA", Stops.<Float>identity()))
+    );
+
+    // Verify
+    assertNotNull(layer.getTextOpacity());
+    assertNotNull(layer.getTextOpacity().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextOpacity().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextOpacity().getFunction()).getProperty());
+    assertEquals(IdentityStops.class, layer.getTextOpacity().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testTextOpacityAsExponentialSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-opacity");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textOpacity(
+        property(
+          "FeaturePropertyA",
+          exponential(
+            stop(0.3f, textOpacity(0.3f))
+          ).withBase(0.5f)
+        )
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getTextOpacity());
+    assertNotNull(layer.getTextOpacity().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextOpacity().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextOpacity().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getTextOpacity().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testTextOpacityAsCategoricalSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-opacity");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textOpacity(
+        property(
+          "FeaturePropertyA",
+          categorical(
+            stop(1.0f, textOpacity(0.3f))
+          )
+        ).withDefaultValue(0.3f)
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getTextOpacity());
+    assertNotNull(layer.getTextOpacity().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextOpacity().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextOpacity().getFunction()).getProperty());
+    assertEquals(CategoricalStops.class, layer.getTextOpacity().getFunction().getStops().getClass());
+    assertEquals(0.3f, ((SourceFunction) layer.getTextOpacity().getFunction()).getDefaultValue());
+  }
+
+  @Test
+  public void testTextOpacityAsCompositeFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-opacity");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textOpacity(
+        composite(
+          "FeaturePropertyA",
+          exponential(
+            stop(0, 0.3f, textOpacity(0.9f))
+          ).withBase(0.5f)
+        ).withDefaultValue(0.3f)
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getTextOpacity());
+    assertNotNull(layer.getTextOpacity().getFunction());
+    assertEquals(CompositeFunction.class, layer.getTextOpacity().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((CompositeFunction) layer.getTextOpacity().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getTextOpacity().getFunction().getStops().getClass());
+    assertEquals(1, ((ExponentialStops) layer.getTextOpacity().getFunction().getStops()).size());
+
+    ExponentialStops<Stop.CompositeValue<Float, Float>, Float> stops =
+      (ExponentialStops<Stop.CompositeValue<Float, Float>, Float>) layer.getTextOpacity().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 testTextColorAsConstant() {
     checkViewIsDisplayed(R.id.mapView);
     Timber.i("text-color");
@@ -1915,6 +2481,77 @@ public class SymbolLayerTest extends BaseStyleTest {
   }
 
   @Test
+  public void testTextColorAsIdentitySourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-color");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textColor(property("FeaturePropertyA", Stops.<String>identity()))
+    );
+
+    // Verify
+    assertNotNull(layer.getTextColor());
+    assertNotNull(layer.getTextColor().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextColor().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextColor().getFunction()).getProperty());
+    assertEquals(IdentityStops.class, layer.getTextColor().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testTextColorAsExponentialSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-color");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textColor(
+        property(
+          "FeaturePropertyA",
+          exponential(
+            stop(Color.RED, textColor(Color.RED))
+          ).withBase(0.5f)
+        )
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getTextColor());
+    assertNotNull(layer.getTextColor().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextColor().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextColor().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getTextColor().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testTextColorAsCategoricalSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-color");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textColor(
+        property(
+          "FeaturePropertyA",
+          categorical(
+            stop("valueA", textColor(Color.RED))
+          )
+        )
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getTextColor());
+    assertNotNull(layer.getTextColor().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextColor().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextColor().getFunction()).getProperty());
+    assertEquals(CategoricalStops.class, layer.getTextColor().getFunction().getStops().getClass());
+  }
+
+  @Test
   public void testTextColorAsIntConstant() {
     checkViewIsDisplayed(R.id.mapView);
     Timber.i("text-color");
@@ -1963,6 +2600,77 @@ public class SymbolLayerTest extends BaseStyleTest {
   }
 
   @Test
+  public void testTextHaloColorAsIdentitySourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-halo-color");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textHaloColor(property("FeaturePropertyA", Stops.<String>identity()))
+    );
+
+    // Verify
+    assertNotNull(layer.getTextHaloColor());
+    assertNotNull(layer.getTextHaloColor().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextHaloColor().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextHaloColor().getFunction()).getProperty());
+    assertEquals(IdentityStops.class, layer.getTextHaloColor().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testTextHaloColorAsExponentialSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-halo-color");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textHaloColor(
+        property(
+          "FeaturePropertyA",
+          exponential(
+            stop(Color.RED, textHaloColor(Color.RED))
+          ).withBase(0.5f)
+        )
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getTextHaloColor());
+    assertNotNull(layer.getTextHaloColor().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextHaloColor().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextHaloColor().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getTextHaloColor().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testTextHaloColorAsCategoricalSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-halo-color");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textHaloColor(
+        property(
+          "FeaturePropertyA",
+          categorical(
+            stop("valueA", textHaloColor(Color.RED))
+          )
+        )
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getTextHaloColor());
+    assertNotNull(layer.getTextHaloColor().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextHaloColor().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextHaloColor().getFunction()).getProperty());
+    assertEquals(CategoricalStops.class, layer.getTextHaloColor().getFunction().getStops().getClass());
+  }
+
+  @Test
   public void testTextHaloColorAsIntConstant() {
     checkViewIsDisplayed(R.id.mapView);
     Timber.i("text-halo-color");
@@ -2011,6 +2719,112 @@ public class SymbolLayerTest extends BaseStyleTest {
   }
 
   @Test
+  public void testTextHaloWidthAsIdentitySourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-halo-width");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textHaloWidth(property("FeaturePropertyA", Stops.<Float>identity()))
+    );
+
+    // Verify
+    assertNotNull(layer.getTextHaloWidth());
+    assertNotNull(layer.getTextHaloWidth().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextHaloWidth().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextHaloWidth().getFunction()).getProperty());
+    assertEquals(IdentityStops.class, layer.getTextHaloWidth().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testTextHaloWidthAsExponentialSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-halo-width");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textHaloWidth(
+        property(
+          "FeaturePropertyA",
+          exponential(
+            stop(0.3f, textHaloWidth(0.3f))
+          ).withBase(0.5f)
+        )
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getTextHaloWidth());
+    assertNotNull(layer.getTextHaloWidth().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextHaloWidth().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextHaloWidth().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getTextHaloWidth().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testTextHaloWidthAsCategoricalSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-halo-width");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textHaloWidth(
+        property(
+          "FeaturePropertyA",
+          categorical(
+            stop(1.0f, textHaloWidth(0.3f))
+          )
+        ).withDefaultValue(0.3f)
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getTextHaloWidth());
+    assertNotNull(layer.getTextHaloWidth().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextHaloWidth().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextHaloWidth().getFunction()).getProperty());
+    assertEquals(CategoricalStops.class, layer.getTextHaloWidth().getFunction().getStops().getClass());
+    assertEquals(0.3f, ((SourceFunction) layer.getTextHaloWidth().getFunction()).getDefaultValue());
+  }
+
+  @Test
+  public void testTextHaloWidthAsCompositeFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-halo-width");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textHaloWidth(
+        composite(
+          "FeaturePropertyA",
+          exponential(
+            stop(0, 0.3f, textHaloWidth(0.9f))
+          ).withBase(0.5f)
+        ).withDefaultValue(0.3f)
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getTextHaloWidth());
+    assertNotNull(layer.getTextHaloWidth().getFunction());
+    assertEquals(CompositeFunction.class, layer.getTextHaloWidth().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((CompositeFunction) layer.getTextHaloWidth().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getTextHaloWidth().getFunction().getStops().getClass());
+    assertEquals(1, ((ExponentialStops) layer.getTextHaloWidth().getFunction().getStops()).size());
+
+    ExponentialStops<Stop.CompositeValue<Float, Float>, Float> stops =
+      (ExponentialStops<Stop.CompositeValue<Float, Float>, Float>) layer.getTextHaloWidth().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 testTextHaloBlurAsConstant() {
     checkViewIsDisplayed(R.id.mapView);
     Timber.i("text-halo-blur");
@@ -2048,6 +2862,112 @@ public class SymbolLayerTest extends BaseStyleTest {
   }
 
   @Test
+  public void testTextHaloBlurAsIdentitySourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-halo-blur");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textHaloBlur(property("FeaturePropertyA", Stops.<Float>identity()))
+    );
+
+    // Verify
+    assertNotNull(layer.getTextHaloBlur());
+    assertNotNull(layer.getTextHaloBlur().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextHaloBlur().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextHaloBlur().getFunction()).getProperty());
+    assertEquals(IdentityStops.class, layer.getTextHaloBlur().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testTextHaloBlurAsExponentialSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-halo-blur");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textHaloBlur(
+        property(
+          "FeaturePropertyA",
+          exponential(
+            stop(0.3f, textHaloBlur(0.3f))
+          ).withBase(0.5f)
+        )
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getTextHaloBlur());
+    assertNotNull(layer.getTextHaloBlur().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextHaloBlur().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextHaloBlur().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getTextHaloBlur().getFunction().getStops().getClass());
+  }
+
+  @Test
+  public void testTextHaloBlurAsCategoricalSourceFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-halo-blur");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textHaloBlur(
+        property(
+          "FeaturePropertyA",
+          categorical(
+            stop(1.0f, textHaloBlur(0.3f))
+          )
+        ).withDefaultValue(0.3f)
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getTextHaloBlur());
+    assertNotNull(layer.getTextHaloBlur().getFunction());
+    assertEquals(SourceFunction.class, layer.getTextHaloBlur().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((SourceFunction) layer.getTextHaloBlur().getFunction()).getProperty());
+    assertEquals(CategoricalStops.class, layer.getTextHaloBlur().getFunction().getStops().getClass());
+    assertEquals(0.3f, ((SourceFunction) layer.getTextHaloBlur().getFunction()).getDefaultValue());
+  }
+
+  @Test
+  public void testTextHaloBlurAsCompositeFunction() {
+    checkViewIsDisplayed(R.id.mapView);
+    Timber.i("text-halo-blur");
+    assertNotNull(layer);
+
+    // Set
+    layer.setProperties(
+      textHaloBlur(
+        composite(
+          "FeaturePropertyA",
+          exponential(
+            stop(0, 0.3f, textHaloBlur(0.9f))
+          ).withBase(0.5f)
+        ).withDefaultValue(0.3f)
+      )
+    );
+
+    // Verify
+    assertNotNull(layer.getTextHaloBlur());
+    assertNotNull(layer.getTextHaloBlur().getFunction());
+    assertEquals(CompositeFunction.class, layer.getTextHaloBlur().getFunction().getClass());
+    assertEquals("FeaturePropertyA", ((CompositeFunction) layer.getTextHaloBlur().getFunction()).getProperty());
+    assertEquals(ExponentialStops.class, layer.getTextHaloBlur().getFunction().getStops().getClass());
+    assertEquals(1, ((ExponentialStops) layer.getTextHaloBlur().getFunction().getStops()).size());
+
+    ExponentialStops<Stop.CompositeValue<Float, Float>, Float> stops =
+      (ExponentialStops<Stop.CompositeValue<Float, Float>, Float>) layer.getTextHaloBlur().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 testTextTranslateAsConstant() {
     checkViewIsDisplayed(R.id.mapView);
     Timber.i("text-translate");