changed $expand filter matching from left-match to contains match (#2327)

* changed $expand filter matching from left-match to contains match

* changelog

* pure substring match is too generous (a regression test checked for that).  Tightened the match up to word boundaries.

* CLean up to avoid intermittent test failure

Co-authored-by: jamesagnew <jamesagnew@gmail.com>

hapi-fhir-docs/src/main/resources/ca/uhn/hapi/fhir/changelog/5_3_0/2327-expand-filter.yaml

@@ -0,0 +1,6 @@
+---
+type: fix
+issue: 2327
+title: "The $expand filter parameter was not matching the ValueSet display value in all cases.  E.g. a ValueSet
+with name 'abc def ghi' would match 'abc def' and 'def' but not 'def ghi'.  This has been corrected so the ValueSet
+will match the filter if any substring of the ValueSet display value matches the $expand filter."

hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/term/BaseTermReadSvcImpl.java

@@ -186,6 +186,7 @@ import static org.apache.commons.lang3.StringUtils.isEmpty;
 import static org.apache.commons.lang3.StringUtils.isNoneBlank;
 import static org.apache.commons.lang3.StringUtils.isNotBlank;
 import static org.apache.commons.lang3.StringUtils.lowerCase;
+import static org.apache.commons.lang3.StringUtils.startsWithIgnoreCase;
 
 public abstract class BaseTermReadSvcImpl implements ITermReadSvc {
 	public static final int DEFAULT_FETCH_SIZE = 250;
@@ -644,27 +645,44 @@ public abstract class BaseTermReadSvcImpl implements ITermReadSvc {
 		}
 	}
 
-	public boolean applyFilter(final String theInput, final String thePrefixToken) {
+	public boolean applyFilter(final String theDisplay, final String theFilterDisplay) {
 		
 		//-- safety check only, no need to apply filter
-		if (theInput == null || thePrefixToken == null)
+		if (theDisplay == null || theFilterDisplay == null)
 			return true;
 
 		// -- sentence case
-		if (org.apache.commons.lang3.StringUtils.startsWithIgnoreCase(theInput, thePrefixToken))
+		if (startsWithIgnoreCase(theDisplay, theFilterDisplay))
 			return true;
 		
 		//-- token case
-		// return true only e.g. the input is 'Body height', thePrefixToken is "he", or 'bo'
-		StringTokenizer tok = new StringTokenizer(theInput);		
-		while (tok.hasMoreTokens()) {
-			if (org.apache.commons.lang3.StringUtils.startsWithIgnoreCase(tok.nextToken(), thePrefixToken))
-				return true;
-		}
-		
+		if (startsWithByWordBoundaries(theDisplay, theFilterDisplay)) return true;
+
 		return false;
 	}
-	
+
+	private boolean startsWithByWordBoundaries(String theDisplay, String theFilterDisplay) {
+		// return true only e.g. the input is 'Body height', theFilterDisplay is "he", or 'bo'
+		StringTokenizer tok = new StringTokenizer(theDisplay);
+		List<String> tokens = new ArrayList<>();
+		while (tok.hasMoreTokens()) {
+			String token = tok.nextToken();
+			if (startsWithIgnoreCase(token, theFilterDisplay))
+				return true;
+			tokens.add(token);
+		}
+
+		// Allow to search by the end of the phrase.  E.g.  "working proficiency" will match "Limited working proficiency"
+		for (int start = 0; start <= tokens.size() - 1; ++ start) {
+			for (int end = start + 1; end <= tokens.size(); ++end) {
+				String sublist = String.join(" ", tokens.subList(start, end));
+				if (startsWithIgnoreCase(sublist, theFilterDisplay))
+					return true;
+			}
+		}
+		return false;
+	}
+
 	@Override
 	@Transactional(propagation = Propagation.REQUIRED)
 	public void expandValueSet(ValueSetExpansionOptions theExpansionOptions, ValueSet theValueSetToExpand, IValueSetConceptAccumulator theValueSetCodeAccumulator) {

hapi-fhir-jpaserver-base/src/test/java/ca/uhn/fhir/jpa/term/BaseTermReadSvcImplTest.java

@@ -0,0 +1,43 @@
+package ca.uhn.fhir.jpa.term;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class BaseTermReadSvcImplTest {
+
+	private final TermReadSvcR5 mySvc = new TermReadSvcR5();
+
+	@Test
+	void applyFilterMatchWords() {
+		assertTrue(mySvc.applyFilter("abc def", "abc def"));
+		assertTrue(mySvc.applyFilter("abc def", "abc"));
+		assertTrue(mySvc.applyFilter("abc def", "def"));
+		assertTrue(mySvc.applyFilter("abc def ghi", "abc def ghi"));
+		assertTrue(mySvc.applyFilter("abc def ghi", "abc def"));
+		assertTrue(mySvc.applyFilter("abc def ghi", "def ghi"));
+	}
+
+	@Test
+	void applyFilterSentenceStart() {
+		assertTrue(mySvc.applyFilter("manifold", "man"));
+		assertTrue(mySvc.applyFilter("manifest destiny", "man"));
+		assertTrue(mySvc.applyFilter("deep sight", "deep sigh"));
+		assertTrue(mySvc.applyFilter("sink cottage", "sink cot"));
+	}
+
+	@Test
+	void applyFilterSentenceEnd() {
+		assertFalse(mySvc.applyFilter("rescue", "cue"));
+		assertFalse(mySvc.applyFilter("very picky", "icky"));
+	}
+
+	@Test
+	void applyFilterSubwords() {
+		assertFalse(mySvc.applyFilter("splurge", "urge"));
+		assertFalse(mySvc.applyFilter("sink cottage", "ink cot"));
+		assertFalse(mySvc.applyFilter("sink cottage", "ink cottage"));
+		assertFalse(mySvc.applyFilter("clever jump startle", "lever jump star"));
+	}
+}