[core] Add a method for statically evaluating font stacks used by a style

2 files changed, 48 insertions, 0 deletions

diff --git a/test/fixtures/style_parser/font_stacks.json b/test/fixtures/style_parser/font_stacks.json
new file mode 100644
index 0000000000..07fe223d46
--- /dev/null
+++ b/test/fixtures/style_parser/font_stacks.json
@@ -0,0 +1,38 @@
+{
+  "version": 8,
+  "sources": {
+    "source": {
+      "type": "vector",
+      "tiles": []
+    }
+  },
+  "layers": [{
+    "id": "a",
+    "type": "symbol",
+    "source": "source",
+    "source-layer": "source-layer",
+    "layout": {
+      "text-font": ["a"]
+    }
+  }, {
+    "id": "a,b",
+    "type": "symbol",
+    "source": "source",
+    "source-layer": "source-layer",
+    "layout": {
+      "text-font": {
+        "stops": [[0, ["a", "b"]]]
+      }
+    }
+  }, {
+    "id": "a,b;a,b,c",
+    "type": "symbol",
+    "source": "source",
+    "source-layer": "source-layer",
+    "layout": {
+      "text-font": {
+        "stops": [[0, ["a", "b"]], [1, ["a", "b", "c"]]]
+      }
+    }
+  }]
+}
diff --git a/test/style/style_parser.cpp b/test/style/style_parser.cpp
index 22b5acb12b..1554c76a27 100644
--- a/test/style/style_parser.cpp
+++ b/test/style/style_parser.cpp
@@ -113,3 +113,13 @@ TEST(StyleParser, ParseTileJSONVector) {
     EXPECT_EQ("attribution", result->attribution);
     EXPECT_EQ("http://a.tiles.mapbox.com/mapbox.streets/{z}-{x}-{y}.vector.pbf?access_token=key", result->tiles[0]);
 }
+
+TEST(StyleParser, FontStacks) {
+    StyleParser parser;
+    parser.parse(util::read_file("test/fixtures/style_parser/font_stacks.json"));
+    auto result = parser.fontStacks();
+    ASSERT_EQ(3, result.size());
+    ASSERT_EQ("a", result[0]);
+    ASSERT_EQ("a,b", result[1]);
+    ASSERT_EQ("a,b,c", result[2]);
+}