Add support for pattern comprehension

Author: FylmTM

language/cypher/src/main/gen/com/neueda/jetbrains/plugin/graphdb/language/cypher/CypherParser.java

@@ -378,6 +378,7 @@ private Expression1 ::= NumberLiteral
               | MapLiteral
               | MapProjection
               | ListComprehension
+              | PatternComprehension
               | ("[" Expression? ("," Expression)* "]")
               | FilterFunctionInvocation
               | ExtractFunctionInvocation
@@ -418,6 +419,8 @@ NoneFunctionInvocation ::= K_NONE "(" FilterExpression ")"
 SingleFunctionInvocation ::= K_SINGLE "(" FilterExpression ")"
 ExistsFunctionInvocation ::= K_EXISTS "(" Expression ")"
 
+PatternComprehension ::= "[" RelationshipsPattern (K_WHERE Expression)? "|" Expression "]"
+
 /*************************
  * Literals
  */

language/cypher/src/main/gen/com/neueda/jetbrains/plugin/graphdb/language/cypher/psi/CypherExpression.java

@@ -31,4 +31,8 @@ public void testSpecialFunctions() {
     public void testMapProjection() {
         doTest(true);
     }
+
+    public void testPatternComprehension() {
+        doTest(true);
+    }
 }

language/cypher/src/main/gen/com/neueda/jetbrains/plugin/graphdb/language/cypher/psi/CypherPatternComprehension.java

@@ -0,0 +1,2 @@
+RETURN [(n)-[]-() | n.property];
+RETURN [(n)-[]-() WHERE n.property = 2 | n.property];