Fix various bugs, improve docs, allow 'null' in JSON, specify behaviour of must_match better

AspectedRouting.Test/MustMatchTest.cs

@@ -0,0 +1,48 @@
+using System.Collections.Generic;
+using AspectedRouting.Language;
+using AspectedRouting.Language.Functions;
+using Xunit;
+
+namespace AspectedRouting.Test
+{
+    public class MustMatchTest
+    {
+        [Fact]
+        public void MustMatch_SimpleInput()
+        {
+            var mapValue = new Mapping(new[] {"residential", "living_street"},
+                new[] {
+                    new Constant("yes"),
+                    new Constant("no")
+                });
+            var mapTag = new Mapping(new[] {"highway"}, new[] {mapValue});
+            var mm = Funcs.MustMatch
+                    .Apply(
+                        new Constant(new[] {new Constant("highway")}),
+                        Funcs.StringStringToTags.Apply(mapTag)
+                    )
+                ;
+
+
+            var residential = mm.Apply(new Constant(new Dictionary<string, string> {
+                {"highway", "residential"}
+            })).Evaluate(new Context());
+            Assert.Equal("yes", residential);
+
+            var living = mm.Apply(new Constant(new Dictionary<string, string> {
+                {"highway", "living_street"}
+            })).Evaluate(new Context());
+            Assert.Equal("no", living);
+
+            var unknown = mm.Apply(new Constant(new Dictionary<string, string> {
+                {"highway", "unknown_type"}
+            })).Evaluate(new Context());
+            Assert.Equal("yes", unknown);
+
+            var missing = mm.Apply(new Constant(new Dictionary<string, string> {
+                {"proposed:highway", "unknown_type"}
+            })).Evaluate(new Context());
+            Assert.Equal("no", missing);
+        }
+    }
+}