Initial attempt at creating a regex modifier for key patterns

src/main/java/org/jabref/logic/formatter/Formatters.java

@@ -16,6 +16,7 @@
 import org.jabref.logic.formatter.bibtexfields.NormalizeNamesFormatter;
 import org.jabref.logic.formatter.bibtexfields.NormalizePagesFormatter;
 import org.jabref.logic.formatter.bibtexfields.OrdinalsToSuperscriptFormatter;
+import org.jabref.logic.formatter.bibtexfields.RegexFormatter;
 import org.jabref.logic.formatter.bibtexfields.RemoveBracesFormatter;
 import org.jabref.logic.formatter.bibtexfields.UnicodeToLatexFormatter;
 import org.jabref.logic.formatter.bibtexfields.UnitsToLatexFormatter;
@@ -56,6 +57,7 @@ public class Formatters {
             new NormalizeNamesFormatter(),
             new NormalizePagesFormatter(),
             new OrdinalsToSuperscriptFormatter(),
+            new RegexFormatter(),
             new RemoveBracesFormatter(),
             new UnitsToLatexFormatter(),
             new EscapeUnderscoresFormatter()
@@ -68,7 +70,16 @@ private Formatters() {
 
     public static Optional<Formatter> getFormatterForModifier(String modifier) {
         Objects.requireNonNull(modifier);
-        Optional<Formatter> formatter = ALL.stream().filter(f -> f.getKey().equals(modifier)).findAny();
+        Optional<Formatter> formatter;
+
+        if (modifier.matches("regex.*")) {
+            String regex = modifier.substring(5);
+            RegexFormatter.setRegex(regex);
+            formatter = ALL.stream().filter(f -> f.getKey().equals("regex")).findAny();
+
+        } else {
+            formatter = ALL.stream().filter(f -> f.getKey().equals(modifier)).findAny();
+        }
         if (formatter.isPresent()) {
             return formatter;
         }

src/main/java/org/jabref/logic/formatter/bibtexfields/RegexFormatter.java

@@ -0,0 +1,49 @@
+package org.jabref.logic.formatter.bibtexfields;
+
+import java.util.Objects;
+
+import org.jabref.logic.l10n.Localization;
+import org.jabref.model.cleanup.Formatter;
+
+public class RegexFormatter implements Formatter {
+
+    private static String[] rex;
+
+    @Override
+    public String getName() {
+        return Localization.lang("Regex");
+    }
+
+    @Override
+    public String getKey() {
+        return "regex";
+    }
+
+    @Override
+    public String format(String oldString) {
+        Objects.requireNonNull(oldString);
+        rex[0] = rex[0].replaceAll("\"", "");
+        rex[1] = rex[1].replaceAll("\"", "");
+
+        return oldString.replaceAll(rex[0], rex[1]);
+    }
+
+    @Override
+    public String getDescription() {
+        return Localization.lang("Add a regular expression for the key pattern.");
+    }
+
+    @Override
+    public String getExampleInput() {
+        return "Please replace the spaces";
+    }
+
+    public static void setRegex(String regex) {
+        regex = regex.substring(1, regex.length() - 1);
+        String[] parts = regex.split("\",\"");
+        parts[0] += "\"";
+        parts[1] = "\"" + parts[1];
+        rex = parts;
+    }
+
+}

src/test/java/org/jabref/logic/bibtexkeypattern/MakeLabelWithDatabaseTest.java

@@ -387,6 +387,14 @@ public void generateKeyAuthIniMany() {
         assertEquals(Optional.of("DoeSmiWon"), entry.getCiteKeyOptional());
     }
 
+    @Test
+    public void generateKeyTitleRegexe() {
+        bibtexKeyPattern.setDefaultValue("[title:regex(\" \",\"-\")]");
+        entry.setField("title", "Please replace the spaces");
+        BibtexKeyPatternUtil.makeAndSetLabel(bibtexKeyPattern, database, entry, preferences);
+        assertEquals(Optional.of("Please-Replace-the-Spaces"), entry.getCiteKeyOptional());
+    }
+
     @Test
     public void generateKeyTitleTitleCase() {
         bibtexKeyPattern.setDefaultValue("[title:title_case]");