From ea786ddedc81c191d5ebf9e076a5bf61111e78eb Mon Sep 17 00:00:00 2001
From: Oliver Egger <oliver.egger@ahdis.ch>
Date: Sat, 26 Oct 2019 09:39:37 +0200
Subject: [PATCH] evaluate FHIRPath for resource or logical model

---
 .../fhir/r5/validation/ValidationEngine.java  |  9 ++++++-
 .../org/hl7/fhir/r5/validation/Validator.java | 24 ++++++++++++++++++-
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/ValidationEngine.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/ValidationEngine.java
index e53db7e12..9201c5752 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/ValidationEngine.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/ValidationEngine.java
@@ -1268,7 +1268,14 @@ public class ValidationEngine implements IValidatorResourceFetcher {
     Element e = Manager.parse(context, new ByteArrayInputStream(cnt.focus), cnt.cntType);
     Manager.compose(context, e, new FileOutputStream(output), (output.endsWith(".json") ? FhirFormat.JSON : FhirFormat.XML), OutputStyle.PRETTY, null);
   }
-  
+
+  public String evaluateFhirPath(String source, String expression) throws Exception {
+    Content cnt = loadContent(source, "validate");
+    FHIRPathEngine fpe = new FHIRPathEngine(context);
+    Element e = Manager.parse(context, new ByteArrayInputStream(cnt.focus), cnt.cntType);
+    return fpe.evaluateToString(e, expression);
+  }
+
   public StructureDefinition snapshot(String source, String version) throws Exception {
     Content cnt = loadContent(source, "validate");
     Resource res = loadResourceByVersion(version, cnt.focus, Utilities.getFileNameForName(source));
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/Validator.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/Validator.java
index 5a924daf0..9ab130e8c 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/Validator.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/Validator.java
@@ -111,7 +111,7 @@ import org.hl7.fhir.utilities.xhtml.XhtmlComposer;
 public class Validator {
 
   public enum EngineMode {
-    VALIDATION, TRANSFORM, NARRATIVE, SNAPSHOT, SCAN, CONVERT
+    VALIDATION, TRANSFORM, NARRATIVE, SNAPSHOT, SCAN, CONVERT, FHIRPATH
   }
 
   private static String getNamedParam(String[] args, String param) {
@@ -243,6 +243,15 @@ public class Validator {
       System.out.println("");
       System.out.println("-convert requires the parameters -source and -output. ig may be used to provide a logical model");
       System.out.println("");
+      System.out.println("Alternatively, you can use the validator to evaluate a FHIRPath expression on a resource or logical model.");
+      System.out.println("To do this, you must provide a specific parameter:");
+      System.out.println("");
+      System.out.println(" -fhirpath [FHIRPath]");
+      System.out.println("");
+      System.out.println("* [FHIRPath] the FHIRPath expression to evaluate");
+      System.out.println("");
+      System.out.println("-fhirpath requires the parameters -source. ig may be used to provide a logical model");
+      System.out.println("");
       System.out.println("Finally, you can use the validator to generate a snapshot for a profile.");
       System.out.println("To do this, you must provide a specific parameter:");
       System.out.println("");
@@ -393,6 +402,7 @@ public class Validator {
       String txLog = null;
       String mapLog = null;
       String lang = null;
+      String fhirpath = null;
       boolean doDebug = false;
 
       // load the parameters - so order doesn't matter
@@ -500,6 +510,15 @@ public class Validator {
           i++;
         } else if (args[i].equals("-convert")) {
           mode = EngineMode.CONVERT;
+        } else if (args[i].equals("-fhirpath")) {
+            mode = EngineMode.FHIRPATH;
+            if (fhirpath == null)
+              if (i+1 == args.length)
+                throw new Error("Specified -fhirpath without indicating a FHIRPath expression");
+              else
+                fhirpath = args[++i];
+            else
+              throw new Exception("Can only nominate a single -fhirpath parameter");
         } else {
           sources.add(args[i]);
         }
@@ -568,6 +587,9 @@ public class Validator {
       } else if (mode == EngineMode.CONVERT) {
         validator.convert(sources.get(0), output);
         System.out.println(" ...convert");
+      } else if (mode == EngineMode.FHIRPATH) {
+        System.out.println(" ...evaluating "+fhirpath);
+        System.out.println(validator.evaluateFhirPath(sources.get(0), fhirpath));
       } else {
         if  (definitions == null)
           throw new Exception("Must provide a defn when doing validation");