Add filter that displays part of a String.

diff --git a/src/main/java/net/pterodactylus/sone/template/SubstringFilter.java b/src/main/java/net/pterodactylus/sone/template/SubstringFilter.java
new file mode 100644 (file)
index 0000000..f0075e4
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+++ b/src/main/java/net/pterodactylus/sone/template/SubstringFilter.java
@@ -0,0 +1,69 @@
+/*
+ * Sone - SubstringFilter.java - Copyright © 2010 David Roden
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.pterodactylus.sone.template;
+
+import java.util.Map;
+
+import net.pterodactylus.util.template.DataProvider;
+import net.pterodactylus.util.template.Filter;
+
+/**
+ * {@link Filter} implementation that executes
+ * {@link String#substring(int, int)} on the given data. It has two parameters:
+ * “start” and “length.” “length” is optional and defaults to “the rest of the
+ * string.” “start” starts at {@code 0} and can be negative to denote starting
+ * at the end of the string.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class SubstringFilter implements Filter {
+
+       /**
+        * {@inheritDoc}
+        */
+       @Override
+       public Object format(DataProvider dataProvider, Object data, Map<String, String> parameters) {
+               String startString = parameters.get("start");
+               String lengthString = parameters.get("length");
+               int start = 0;
+               try {
+                       start = Integer.parseInt(startString);
+               } catch (NumberFormatException nfe1) {
+                       /* ignore. */
+               }
+               String dataString = String.valueOf(data);
+               int dataLength = dataString.length();
+               if (lengthString == null) {
+                       if (start < 0) {
+                               return dataString.substring(dataLength + start);
+                       }
+                       return dataString.substring(start);
+               }
+               int length = Integer.MAX_VALUE;
+               try {
+                       length = Integer.parseInt(lengthString);
+               } catch (NumberFormatException nfe1) {
+                       /* ignore. */
+               }
+               if (start < 0) {
+                       return dataString.substring(dataLength + start, Math.min(dataLength, dataLength + start + length));
+               }
+               return dataString.substring(start, Math.min(dataLength, start + length));
+       }
+
+}