Liquid enhancements2

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/utils/LiquidEngine.java

@@ -386,7 +386,7 @@ public void evaluate(StringBuilder b, Base resource, LiquidEngineContext ctxt) t
             break;
           }          
           if (lctxt.globalVars.containsKey(varName)) {
-            throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_VARIABLE_ALREADY_ASSIGNED, varName));
+            lctxt.globalVars.remove(varName);
           }
           lctxt.loopVars.put(varName, o);
           boolean wantBreak = false;

org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/fhirpath/FHIRPathEngine.java

@@ -406,6 +406,23 @@ public ExpressionNode getNode() {
     }
 
   }
+
+  /**
+   * Parse a path for later use using execute, but allow the path to be part of some other syntax (e.g. a Liquid expression)
+   * 
+   * @param lexer
+   * @return
+   * @throws FHIRLexerException
+   */
+  public ExpressionNodeWithOffset parsePartialExpression(FHIRLexer lexer) throws FHIRLexerException {
+    if (lexer.done()) {
+      throw lexer.error("Path cannot be empty");
+    }
+    ExpressionNode result = parseExpression(lexer, true);
+    result.check();
+    return new ExpressionNodeWithOffset(lexer.getCurrentStart(), result);    
+  }
+
   /**
    * Parse a path for later use using execute
    *