Support triple quote strings to disambiguate between String and EscapedJsonPointer (#5655)

* Introduce RawString type to allow strings that begin with forward slash

Signed-off-by: Craig Perkins <cwperx@amazon.com>

* Add tests in GenericExpressionEvaluator_ConditionalIT

Signed-off-by: Craig Perkins <cwperx@amazon.com>

* Address comments

Signed-off-by: Craig Perkins <cwperx@amazon.com>

* Improve coverage

Signed-off-by: Craig Perkins <cwperx@amazon.com>

---------

Signed-off-by: Craig Perkins <cwperx@amazon.com>
Signed-off-by: Craig Perkins <craig5008@gmail.com>

Author: cwperks

data-prepper-expression/src/main/antlr/DataPrepperExpression.g4

@@ -271,6 +271,7 @@ VariableNameCharacter
 
 String
     : DOUBLEQUOTE StringCharacters? DOUBLEQUOTE
+    | DOUBLEQUOTE DOUBLEQUOTE DOUBLEQUOTE StringCharacters? DOUBLEQUOTE DOUBLEQUOTE DOUBLEQUOTE
     ;
 
 fragment

data-prepper-expression/src/main/java/org/opensearch/dataprepper/expression/ParseTreeCoercionService.java

@@ -78,9 +78,7 @@ public Object coercePrimaryTerminalNode(final TerminalNode node, final Event eve
             case DataPrepperExpressionParser.JsonPointer:
                 return resolveJsonPointerValue(nodeStringValue, event);
             case DataPrepperExpressionParser.String:
-                final String nodeStringValueWithQuotesStripped = nodeStringValue.substring(1,
-                        nodeStringValue.length() - 1);
-                return nodeStringValueWithQuotesStripped;
+                return nodeStringValue.replaceAll("^\"{1,3}|\"{1,3}$", "");
             case DataPrepperExpressionParser.Integer:
                 Long longValue = Long.valueOf(nodeStringValue);
                 if (longValue > Integer.MAX_VALUE || longValue < Integer.MIN_VALUE) {

data-prepper-expression/src/test/java/org/opensearch/dataprepper/expression/GenericExpressionEvaluator_ConditionalIT.java

@@ -192,6 +192,8 @@ private static Stream<Arguments> validExpressionArguments() {
                 arguments("/should_drop", event("{\"should_drop\": true}"), true),
                 arguments("/should_drop", event("{\"should_drop\": false}"), false),
                 arguments("/logs/2/should_drop", event("{\"logs\": [{}, {}, {\"should_drop\": true}]}"), true),
+                arguments("/path == \"\"\"/path/to/route\"\"\"", event("{\"path\": \"/path/to/route\"}"), true),
+                arguments("/path == \"\"\"/path/to/route\"\"\"", event("{\"path\": \"/incorrect/path\"}"), false),
                 arguments(
                         escapedJsonPointer(ALL_JACKSON_EVENT_GET_SUPPORTED_CHARACTERS) + " == true",
                         complexEvent(ALL_JACKSON_EVENT_GET_SUPPORTED_CHARACTERS, true),

data-prepper-expression/src/test/java/org/opensearch/dataprepper/expression/ParseTreeCoercionServiceTest.java

@@ -226,6 +226,18 @@ void testCoerceTerminalNodeEscapeJsonPointerTypeUnSupportedValues() {
         assertThrows(ExpressionCoercionException.class, () -> objectUnderTest.coercePrimaryTerminalNode(terminalNode, testEvent));
     }
 
+    @ParameterizedTest
+    @MethodSource("provideSupportedJsonPointerValues")
+    void testCoerceTerminalNodeTripleQuoteStringTypeSupportedValues(final Object testValue) {
+        final String testKey = "/testKey";
+        final String testTruipleQuoteStringKey = "\"\"\"/testKey\"\"\"";
+        when(token.getType()).thenReturn(DataPrepperExpressionParser.String);
+        when(terminalNode.getSymbol()).thenReturn(token);
+        when(terminalNode.getText()).thenReturn(testTruipleQuoteStringKey);
+        final Object result = objectUnderTest.coercePrimaryTerminalNode(terminalNode, null);
+        assertThat(result, equalTo(testKey));
+    }
+
     @Test
     void testCoerceTerminalNodeJsonPointerTypeUnSupportedValues() {
         final String testKey1 = "key1";