Expressions / introduced the case operator

This operator is used for if/else control flow

test/spec/ol/style/expressions.test.js

@@ -294,6 +294,94 @@ describe('ol.style.expressions', function() {
     });
   });
 
+  describe('case operator', function() {
+    let context;
+
+    beforeEach(function () {
+      context = {
+        variables: [],
+        attributes: [],
+        stringLiteralsMap: {}
+      };
+    });
+
+    it('correctly guesses the output type', function() {
+      expect(getValueType(['case', true, 0, false, [3, 4, 5], 'green']))
+        .to.eql(ValueTypes.NONE);
+      expect(getValueType(['case', true, 0, false, 1, 2]))
+        .to.eql(ValueTypes.NUMBER);
+      expect(getValueType(['case', true, [0, 0, 0], true, [1, 2, 3], ['get', 'attr'], [4, 5, 6, 7], [8, 9, 0]]))
+        .to.eql(ValueTypes.COLOR | ValueTypes.NUMBER_ARRAY);
+      expect(getValueType(['case', true, 'red', true, 'yellow', ['get', 'attr'], 'green', 'white']))
+        .to.eql(ValueTypes.COLOR | ValueTypes.STRING);
+      expect(getValueType(['case', true, [0, 0], false, [1, 1], [2, 2]]))
+        .to.eql(ValueTypes.NUMBER_ARRAY);
+    });
+
+    it('throws if no single output type could be inferred', function() {
+      let thrown = false;
+      try {
+        expressionToGlsl(context, ['case', false, 'red', true, 'yellow', 'green'], ValueTypes.COLOR);
+      } catch (e) {
+        thrown = true;
+      }
+      expect(thrown).to.be(false);
+
+      try {
+        expressionToGlsl(context, ['case', true, 'red', true, 'yellow', 'green']);
+      } catch (e) {
+        thrown = true;
+      }
+      expect(thrown).to.be(true);
+
+      thrown = false;
+      try {
+        expressionToGlsl(context, ['case', true, 'red', false, 'yellow', 'green'], ValueTypes.NUMBER);
+      } catch (e) {
+        thrown = true;
+      }
+      expect(thrown).to.be(true);
+
+      thrown = false;
+      try {
+        expressionToGlsl(context, ['case', true, 'red', false, 'yellow', 'not_a_color'], ValueTypes.COLOR);
+      } catch (e) {
+        thrown = true;
+      }
+      expect(thrown).to.be(true);
+    });
+
+    it('throws if invalid argument count', function() {
+      let thrown = false;
+      try {
+        expressionToGlsl(context, ['case', true, 0, false, 1]);
+      } catch (e) {
+        thrown = true;
+      }
+      expect(thrown).to.be(true);
+
+      thrown = false;
+      try {
+        expressionToGlsl(context, ['case', true, 0]);
+      } catch (e) {
+        thrown = true;
+      }
+      expect(thrown).to.be(true);
+
+      try {
+        expressionToGlsl(context, ['case', false]);
+      } catch (e) {
+        thrown = true;
+      }
+      expect(thrown).to.be(true);
+    });
+
+    it('correctly parses the expression (colors)', function() {
+      expect(expressionToGlsl(context, ['case', ['>', ['get', 'attr'], 3], 'red', ['>', ['get', 'attr'], 1], 'yellow', 'white'], ValueTypes.COLOR))
+        .to.eql('((a_attr > 3.0) ? vec4(1.0, 0.0, 0.0, 1.0) : ((a_attr > 1.0) ? vec4(1.0, 1.0, 0.0, 1.0) : vec4(1.0, 1.0, 1.0, 1.0)))');
+    });
+  });
+
   describe('match operator', function() {
     let context;