support constant [] and {} expression

libraries/Microsoft.Bot.Builder.Dialogs.Adaptive/AdaptiveComponentRegistration.cs

@@ -76,7 +76,6 @@ public override IEnumerable<TypeRegistration> GetTypes()
             yield return new TypeRegistration<ForeachPage>(ForeachPage.DeclarativeType);
             yield return new TypeRegistration<HttpRequest>(HttpRequest.DeclarativeType);
             yield return new TypeRegistration<IfCondition>(IfCondition.DeclarativeType);
-            yield return new TypeRegistration<InitProperty>(InitProperty.DeclarativeType);
             yield return new TypeRegistration<LogAction>(LogAction.DeclarativeType);
             yield return new TypeRegistration<RepeatDialog>(RepeatDialog.DeclarativeType);
             yield return new TypeRegistration<ReplaceDialog>(ReplaceDialog.DeclarativeType);

libraries/Microsoft.Bot.Builder.LanguageGeneration/Analyzer.cs

@@ -227,7 +227,7 @@ private AnalyzerResult AnalyzeExpressionDirectly(Expression exp)
         private AnalyzerResult AnalyzeExpression(string exp)
         {
             var result = new AnalyzerResult();
-            exp = exp.TrimStart('@').TrimStart('{').TrimEnd('}');
+            exp = exp.TrimExpression();
             var parsed = _expressionParser.Parse(exp);
 
             var references = parsed.References();

libraries/Microsoft.Bot.Builder.LanguageGeneration/Evaluator.cs

@@ -305,7 +305,7 @@ private bool EvalExpressionInCondition(string exp)
         {
             try
             {
-                exp = exp.TrimStart('@').TrimStart('{').TrimEnd('}');
+                exp = exp.TrimExpression();
                 var (result, error) = EvalByExpressionEngine(exp, CurrentTarget().Scope);
 
                 if (error != null
@@ -328,7 +328,7 @@ private bool EvalExpressionInCondition(string exp)
 
         private object EvalExpression(string exp)
         {
-            exp = exp.TrimStart('@').TrimStart('{').TrimEnd('}');
+            exp = exp.TrimExpression();
             var (result, error) = EvalByExpressionEngine(exp, CurrentTarget().Scope);
             if (error != null)
             {

libraries/Microsoft.Bot.Builder.LanguageGeneration/Expander.cs

@@ -317,7 +317,7 @@ private bool EvalExpressionInCondition(string exp)
         {
             try
             {
-                exp = exp.TrimStart('@').TrimStart('{').TrimEnd('}');
+                exp = exp.TrimExpression();
                 var (result, error) = EvalByExpressionEngine(exp, CurrentTarget().Scope);
 
                 if (error != null
@@ -340,7 +340,7 @@ private bool EvalExpressionInCondition(string exp)
 
         private List<string> EvalExpression(string exp)
         {
-            exp = exp.TrimStart('@').TrimStart('{').TrimEnd('}');
+            exp = exp.TrimExpression();
             var (result, error) = EvalByExpressionEngine(exp, CurrentTarget().Scope);
             if (error != null)
             {

libraries/Microsoft.Bot.Builder.LanguageGeneration/Extensions.cs

@@ -79,6 +79,23 @@ public static string Escape(this string text)
             }));
         }
 
+        /// <summary>
+        /// trim expression. @{abc} => abc,  @{a == {}} => a == {}.
+        /// </summary>
+        /// <param name="expression">input expression string.</param>
+        /// <returns>pure expression string.</returns>
+        public static string TrimExpression(this string expression)
+        {
+            var result = expression.Trim().TrimStart('@').Trim();
+
+            if (result.StartsWith("{") && result.EndsWith("}"))
+            {
+                result = result.Substring(1, result.Length - 2);
+            }
+
+            return result;
+        }
+
         /// <summary>
         /// Normalize authored path to os path.
         /// </summary>

libraries/Microsoft.Bot.Builder.LanguageGeneration/LGFileLexer.g4

@@ -43,9 +43,11 @@ fragment NUMBER: '0'..'9';
 
 fragment WHITESPACE : ' '|'\t'|'\ufeff'|'\u00a0';
 
+fragment EMPTY_OBJECT: '{' WHITESPACE* '}';
+
 fragment STRING_LITERAL : ('\'' (~['\r\n])* '\'') | ('"' (~["\r\n])* '"');
 
-fragment EXPRESSION_FRAGMENT : '@' '{' (STRING_LITERAL| ~[\r\n{}'"] )*? '}';
+fragment EXPRESSION_FRAGMENT : '@' '{' (STRING_LITERAL| ~[\r\n{}'"] | EMPTY_OBJECT )*? '}';
 
 fragment ESCAPE_CHARACTER_FRAGMENT : '\\' ~[\r\n]?;
 

libraries/Microsoft.Bot.Builder.LanguageGeneration/StaticChecker.cs

@@ -372,7 +372,7 @@ public override List<Diagnostic> VisitNormalTemplateString([NotNull] LGFileParse
         private List<Diagnostic> CheckExpression(string exp, ParserRuleContext context)
         {
             var result = new List<Diagnostic>();
-            exp = exp.TrimStart('@').TrimStart('{').TrimEnd('}');
+            exp = exp.TrimExpression();
 
             try
             {

libraries/Microsoft.Bot.Expressions/BuiltInFunctions.cs

@@ -2403,6 +2403,57 @@ private static (object, string) IndicesAndValues(Expression expression, object s
 
         private static bool IsSameDay(DateTime date1, DateTime date2) => date1.Year == date2.Year && date1.Month == date2.Month && date1.Day == date2.Day;
 
+        private static bool IsEqual(IReadOnlyList<dynamic> args)
+        {
+            if (args[0] == null)
+            {
+                return args[1] == null;
+            }
+
+            if (TryParseList(args[0], out IList l0) && l0.Count == 0 && (TryParseList(args[1], out IList l1) && l1.Count == 0))
+            {
+                return true;
+            }
+
+            if (GetPropertyCount(args[0]) == 0 && GetPropertyCount(args[1]) == 0)
+            {
+                return true;
+            }
+
+            try
+            {
+                return args[0] == args[1];
+            }
+            catch
+            {
+                return false;
+            }
+        }
+
+        /// <summary>
+        /// Get the property count of an object.
+        /// </summary>
+        /// <param name="obj">input object.</param>
+        /// <returns>property count.</returns>
+        private static int GetPropertyCount(dynamic obj)
+        {
+            if (obj is IDictionary dictionary)
+            {
+                return dictionary.Count;
+            }
+            else if (obj is JObject jobj)
+            {
+                return jobj.Properties().Count();
+            }
+            else if (!(obj is JValue) && obj.GetType().IsValueType == false && obj.GetType().FullName != "System.String")
+            {
+                // exclude constant type.
+                return obj.GetType().GetProperties().Length;
+            }
+
+            return -1;
+        }
+
         private static Dictionary<string, ExpressionEvaluator> BuildFunctionLookup()
         {
             var functions = new List<ExpressionEvaluator>
@@ -2577,8 +2628,9 @@ private static Dictionary<string, ExpressionEvaluator> BuildFunctionLookup()
                 // Booleans
                 Comparison(ExpressionType.LessThan, args => args[0] < args[1], ValidateBinaryNumberOrString, VerifyNumberOrString),
                 Comparison(ExpressionType.LessThanOrEqual, args => args[0] <= args[1], ValidateBinaryNumberOrString, VerifyNumberOrString),
-                Comparison(ExpressionType.Equal, args => args[0] == args[1], ValidateBinary),
-                Comparison(ExpressionType.NotEqual, args => args[0] != args[1], ValidateBinary),
+
+                Comparison(ExpressionType.Equal, IsEqual, ValidateBinary),
+                Comparison(ExpressionType.NotEqual, args => !IsEqual(args), ValidateBinary),
                 Comparison(ExpressionType.GreaterThan, args => args[0] > args[1], ValidateBinaryNumberOrString, VerifyNumberOrString),
                 Comparison(ExpressionType.GreaterThanOrEqual, args => args[0] >= args[1], ValidateBinaryNumberOrString, VerifyNumberOrString),
                 Comparison(ExpressionType.Exists, args => args[0] != null, ValidateUnary, VerifyNotNull),

libraries/Microsoft.Bot.Expressions/parser/Expression.g4

@@ -20,6 +20,7 @@ expression
 
 primaryExpression 
     : '(' expression ')'                      #parenthesisExp
+    | CONSTANT                                #constantAtom
     | NUMBER                                  #numericAtom
     | STRING                                  #stringAtom
     | IDENTIFIER                              #idAtom
@@ -45,4 +46,6 @@ NEWLINE : '\r'? '\n' -> skip;
 
 STRING : ('\'' (~'\'')* '\'') | ('"' (~'"')* '"');
 
+CONSTANT : ('[' WHITESPACE* ']') | ('{' WHITESPACE* '}');
+
 INVALID_TOKEN_DEFAULT_MODE : . ;

libraries/Microsoft.Bot.Expressions/parser/ExpressionEngine.cs

@@ -8,6 +8,7 @@
 using Antlr4.Runtime;
 using Antlr4.Runtime.Misc;
 using Antlr4.Runtime.Tree;
+using Newtonsoft.Json.Linq;
 
 namespace Microsoft.Bot.Expressions
 {
@@ -171,6 +172,22 @@ public override Expression VisitStringAtom([NotNull] ExpressionParser.StringAtom
                 }
             }
 
+            public override Expression VisitConstantAtom([NotNull] ExpressionParser.ConstantAtomContext context)
+            {
+                var text = context.GetText();
+                if (string.IsNullOrWhiteSpace(text.TrimStart('[').TrimEnd(']')))
+                {
+                    return Expression.ConstantExpression(new JArray());
+                }
+
+                if (string.IsNullOrWhiteSpace(text.TrimStart('{').TrimEnd('}')))
+                {
+                    return Expression.ConstantExpression(new JObject());
+                }
+
+                throw new Exception($"Unregonized constant: {text}");
+            }
+
             private Expression MakeExpression(string type, params Expression[] children)
                 => Expression.MakeExpression(_lookup(type), children);