From 016f13f54bc955b87a6a1b9a37dd605aa280d2e3 Mon Sep 17 00:00:00 2001
From: Jules Jacobsen <j.jacobsen@qmul.ac.uk>
Date: Wed, 3 Apr 2019 14:56:56 +0100
Subject: [PATCH] Add CurieUtil.getCuriePrefix(iri) for Issue #4

---
 src/main/java/org/prefixcommons/CurieUtil.java     | 8 ++++++++
 src/test/java/org/prefixcommons/CurieUtilTest.java | 5 +++++
 2 files changed, 13 insertions(+)

diff --git a/src/main/java/org/prefixcommons/CurieUtil.java b/src/main/java/org/prefixcommons/CurieUtil.java
index 9f616cf..10087c9 100644
--- a/src/main/java/org/prefixcommons/CurieUtil.java
+++ b/src/main/java/org/prefixcommons/CurieUtil.java
@@ -92,6 +92,14 @@ public Optional<String> getCurie(String iri) {
     }
   }
 
+  public Optional<String> getCuriePrefix(String iri) {
+    String prefix = trie.getMatchingPrefix(iri);
+    if (prefix.equals("")) {
+      return Optional.empty();
+    }
+    return Optional.of(curieMap.inverse().get(prefix));
+  }
+
   /***
    * Expands a CURIE to a full IRI, if mapped.
    * 
diff --git a/src/test/java/org/prefixcommons/CurieUtilTest.java b/src/test/java/org/prefixcommons/CurieUtilTest.java
index 114ade7..cfb5fff 100644
--- a/src/test/java/org/prefixcommons/CurieUtilTest.java
+++ b/src/test/java/org/prefixcommons/CurieUtilTest.java
@@ -88,4 +88,9 @@ public void fromJsonLdFile() throws IOException {
         is(Optional.of("http://purl.obolibrary.org/obo/XAO_foo")));
   }
 
+  @Test
+  public void getIriPrefix() {
+    assertThat(util.getCuriePrefix("http://x.org/a_12345"), is(Optional.of("A")));
+    assertThat(util.getCuriePrefix("http://x.org/C_C12345"), is(Optional.of("CC")));
+  }
 }