Merge pull request #12338 from vespa-engine/bratseth/truncate-expressions-in-messages

Trunkcate expressions in messages

3 files changed, 25 insertions, 1 deletions

diff --git a/vespajlib/abi-spec.json b/vespajlib/abi-spec.json
index b8b6716d879..04f859e2802 100644
--- a/vespajlib/abi-spec.json
+++ b/vespajlib/abi-spec.json
@@ -3022,7 +3022,8 @@
       "public static boolean isTextCharacter(int)",
       "public static java.util.OptionalInt validateTextString(java.lang.String)",
       "public static boolean isDisplayable(int)",
-      "public static java.lang.String stripInvalidCharacters(java.lang.String)"
+      "public static java.lang.String stripInvalidCharacters(java.lang.String)",
+      "public static java.lang.String truncate(java.lang.String, int)"
     ],
     "fields": []
   },
diff --git a/vespajlib/src/main/java/com/yahoo/text/Text.java b/vespajlib/src/main/java/com/yahoo/text/Text.java
index 706fd1583a3..85b28639d89 100644
--- a/vespajlib/src/main/java/com/yahoo/text/Text.java
+++ b/vespajlib/src/main/java/com/yahoo/text/Text.java
@@ -174,4 +174,16 @@ public final class Text {
         return stripped != null ? stripped.toString() : string;
     }
 
+    /**
+     * Returns a string which is never larger than the given number of characters.
+     * If the string is longer than the given length it will be truncated.
+     * If length is 4 or less the string will be truncated to length.
+     * If length is longer than 4, it will be truncated at length-4 with " ..." added at the end.
+     */
+    public static String truncate(String s, int length) {
+        if (s.length() <= length) return s;
+        if (length <= 4) return s.substring(0, length);
+        return s.substring(0, length - 4) + " ...";
+    }
+
 }
diff --git a/vespajlib/src/test/java/com/yahoo/text/TextTestCase.java b/vespajlib/src/test/java/com/yahoo/text/TextTestCase.java
index e733b838c39..8bb8b2aaad5 100644
--- a/vespajlib/src/test/java/com/yahoo/text/TextTestCase.java
+++ b/vespajlib/src/test/java/com/yahoo/text/TextTestCase.java
@@ -61,4 +61,15 @@ public class TextTestCase {
         assertFalse(Text.isDisplayable(0));
     }
 
+    @Test
+    public void testTruncate() {
+        assertEquals("ab", Text.truncate("ab", 5));
+        assertEquals("ab", Text.truncate("ab", 6));
+        assertEquals("ab", Text.truncate("ab", 2));
+        assertEquals("a",  Text.truncate("ab", 1));
+        assertEquals("",   Text.truncate("ab", 0));
+        assertEquals("ab c",  Text.truncate("ab cde", 4));
+        assertEquals("a ...", Text.truncate("ab cde", 5));
+    }
+
 }