added empty list and empty structure handling

Author: dprzybyl

app/aem/core/src/main/antlr/ApmLang.g4

@@ -33,7 +33,7 @@ name
     ;
 
 privilegeName
-    : IDENTIFIER ':' IDENTIFIER
+    : IDENTIFIER COLON IDENTIFIER
     ;
 
 path
@@ -42,7 +42,7 @@ path
     ;
 
 array
-    : ARRAY_BEGIN arrayValue (',' arrayValue)* ARRAY_END
+    : ARRAY_BEGIN (arrayValue (COMMA arrayValue)*)? ARRAY_END
     ;
 
 arrayValue
@@ -53,11 +53,11 @@ arrayValue
     ;
 
 structure
-    : STRUCTURE_BEGIN structureEntry (',' structureEntry)* STRUCTURE_END
+    : STRUCTURE_BEGIN (structureEntry (COMMA structureEntry)*)? STRUCTURE_END
     ;
 
 structureEntry
-    : structureKey ':' structureValue
+    : structureKey COLON structureValue
     ;
 
 structureKey
@@ -156,7 +156,7 @@ flag
     ;
 
 body
-    : BLOCK_BEGIN command+ BLOCK_END
+    : BLOCK_BEGIN command* BLOCK_END
     ;
 
 /*
@@ -176,6 +176,12 @@ STRUCTURE_BEGIN
 STRUCTURE_END
     : '}'
     ;
+COMMA
+    : ','
+    ;
+COLON
+    : ':'
+    ;
 BLOCK_BEGIN
     : 'begin'
     | 'BEGIN'

app/aem/core/src/main/java/com/cognifide/apm/core/grammar/ScriptRunner.java

@@ -145,6 +145,10 @@ public Status visitRequireVariable(RequireVariableContext ctx) {
     public Status visitForEach(ForEachContext ctx) {
       List<Map<String, ApmType>> values = readValues(ctx);
       ListIterator<Map<String, ApmType>> iterator = values.listIterator();
+      if (!iterator.hasNext() && shouldVisitNextChild()) {
+        String key = ctx.IDENTIFIER().toString();
+        progress(ctx, Status.SKIPPED, "for-each", String.format("%s is always empty", key));
+      }
       while (iterator.hasNext() && shouldVisitNextChild()) {
         try {
           int index = iterator.nextIndex();

app/aem/core/src/test/groovy/com/cognifide/apm/core/grammar/ScriptRunnerTest.groovy

@@ -92,7 +92,9 @@ class ScriptRunnerTest extends Specification {
                      "Executing command SHOW \"t\"",
                      "Executing command SHOW [3, \"ab\"]",
                      "Executing command SHOW [\"a\", \"b\", \"c\", \"d\", 1, 2]",
-                     "Executing command SHOW [\n\t[\"a\", \"b\"],\n\t[\"c\", \"d\"]\n]"]
+                     "Executing command SHOW [\n\t[\"a\", \"b\"],\n\t[\"c\", \"d\"]\n]",
+                     "Executing command SHOW []",
+                     "Executing command SHOW {}"]
     }
 
     def "run macro"() {

app/aem/core/src/test/resources/define.apm

@@ -43,6 +43,8 @@ DEFINE tab3 [['a', 'b'], ['c', 'd']]
 DEFINE obj {x:'a', y:1, z:['c', 1], 't':'t'}
 DEFINE tabEnum [a, b, "c", "d", 1, 2]
 DEFINE tab4 [1 + 2, "a" + "b"]
+DEFINE emptyList []
+DEFINE emptyMap {}
 SHOW $a
 SHOW $b
 SHOW $tab1
@@ -60,3 +62,5 @@ SHOW ${obj[t]}
 SHOW $tab4
 SHOW $tabEnum
 SHOW $tab3
+SHOW $emptyList
+SHOW $emptyMap