From 6ae850ab628bec600a537aad447d04a695465d06 Mon Sep 17 00:00:00 2001
From: Jonatan Asketorp
 <2598631+k3KAW8Pnf7mkmdSMPHz27@users.noreply.github.com>
Date: Tue, 5 May 2020 13:50:15 -0400
Subject: [PATCH] Add modifier to truncate a BibTex key

---
 .../org/jabref/logic/bibtexkeypattern/BracketedPattern.java  | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/main/java/org/jabref/logic/bibtexkeypattern/BracketedPattern.java b/src/main/java/org/jabref/logic/bibtexkeypattern/BracketedPattern.java
index 8c0d7ff3a83..8781782375f 100644
--- a/src/main/java/org/jabref/logic/bibtexkeypattern/BracketedPattern.java
+++ b/src/main/java/org/jabref/logic/bibtexkeypattern/BracketedPattern.java
@@ -377,6 +377,11 @@ static String applyModifiers(final String label, final List<String> parts, final
                     }
                 }
                 resultingLabel = abbreviateSB.toString();
+            } else if (modifier.matches("truncate[\\d]+")) {
+                // Truncate by keeping the first N characters and remove trailing white spaces.
+                int N = Integer.parseInt(modifier.substring(8));
+                N = Math.min(N, resultingLabel.length());
+                resultingLabel = resultingLabel.substring(0, N).stripTrailing();
             } else {
                 Optional<Formatter> formatter = Formatters.getFormatterForModifier(modifier);
                 if (formatter.isPresent()) {