1 files changed, 116 insertions, 0 deletions
diff --git a/src/main/java/bjc/esodata/DefaultList.java b/src/main/java/bjc/esodata/DefaultList.java
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+++ b/src/main/java/bjc/esodata/DefaultList.java
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+package bjc.esodata;
+
+import java.util.AbstractList;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * A list that has a default value that out-of-bounds accesses return.
+ *
+ * @author Ben Culkin
+ * @param <ValueType>
+ *                The type of the values contained in the list.
+ */
+public class DefaultList<ValueType> extends AbstractList<ValueType> {
+	/*
+	 * @NOTE 9/17/18
+	 *
+	 * A possible feature to add would be the ability to set a 'default
+	 * index', so that the default value is 'whatever is at that list index'
+	 *
+	 * Of course, this would cause an exception if that index was out of
+	 * bounds, but what are you going to do?
+	 */
+
+	private ValueType defVal;
+
+	private List<ValueType> backing;
+
+	/**
+	 * Create a new DefaultList.
+	 */
+	public DefaultList() {
+		this(new ArrayList<>(), null);
+	}
+
+	/**
+	 * Create a new DefaultList, with a set default value.
+	 * 
+	 * @param defVal
+	 *                The default value for the list.
+	 */
+	public DefaultList(ValueType defVal) {
+		this(new ArrayList<>(), defVal);
+	}
+
+	/**
+	 * Create a new DefaultList, with a specific backing list.
+	 * 
+	 * @param backer
+	 *                The backing list to use.
+	 * 
+	 */
+	public DefaultList(List<ValueType> backer) {
+		this(backer, null);
+	}
+
+	/**
+	 * Create a new DefaultList, with a set default value.
+	 * 
+	 * @param backer
+	 *                The backing list to use.
+	 * 
+	 * @param defVal
+	 *                The default value for the list.
+	 */
+	public DefaultList(List<ValueType> backer, ValueType defVal) {
+		this.defVal = defVal;
+
+		this.backing = backer;
+	}
+
+	/**
+	 * Get the default value.
+	 * 
+	 * @return The default value.
+	 */
+	public ValueType getDefault() {
+		return defVal;
+	}
+
+	/**
+	 * Set the default value.
+	 * 
+	 * @param defVal The default value.
+	 */
+	public void setDefault(ValueType defVal) {
+		this.defVal = defVal;
+	}
+
+	@Override
+	public ValueType get(int idx) {
+		if (idx < 0 || idx >= backing.size()) return defVal;
+
+		return backing.get(idx);
+	}
+
+	@Override
+	public int size() {
+		return backing.size();
+	}
+
+	@Override
+	public ValueType set(int idx, ValueType val) {
+		return backing.set(idx, val);
+	}
+
+	@Override
+	public void add(int idx, ValueType val) {
+		backing.add(idx, val);
+	}
+
+	@Override
+	public ValueType remove(int idx) {
+		return backing.remove(idx);
+	}
+}