Adding adapter generic array T using T object comparator.

src/main/java/org/jsuffixarrays/GenericArrayAdapter.java

@@ -0,0 +1,69 @@
+package org.jsuffixarrays;
+
+import java.util.Comparator;
+import java.util.Map.Entry;
+import java.util.TreeMap;
+
+/**
+ * An adapter for constructing suffix arrays on generic arrays.
+ *
+ * @author Anton Olsson <abc2386@gmail.com> for friprogramvarusyndikatet.se
+ */
+class GenericArrayAdapter<T> {
+
+    private final ISuffixArrayBuilder delegate;
+    int[] input;
+    TreeMap<T, Integer> tokIDs;
+    private final Comparator<? super T> comparator;
+
+    public GenericArrayAdapter(ISuffixArrayBuilder builder) {
+        // TODO make sure T is comparable
+        this.delegate = builder;
+        this.comparator = null;
+    }
+
+    public GenericArrayAdapter(ISuffixArrayBuilder builder, Comparator<? super T> comparator) {
+        // TODO make sure that comparator != null or T is comparable
+        this.delegate = builder;
+        this.comparator = comparator;
+    }
+
+    /**
+     * Construct a suffix array for a given generic token array.
+     */
+    public int[] buildSuffixArray(T[] tokens) {
+        final int length = tokens.length;
+        /*
+         * Allocate slightly more space, some suffix construction strategies need it and
+         * we don't want to waste space for multiple symbol mappings.
+         */
+        this.input = new int[length + SuffixArrays.MAX_EXTRA_TRAILING_SPACE];
+
+        //System.out.println("Renaming tokens ...");
+        /*
+         * Here we create a mapping for the token to an integer id which we
+         * can use in the suffax array construction algorithm.
+         */
+        this.tokIDs = new TreeMap<T, Integer>(comparator);
+
+        // put and order all tokens in tokIDs
+        for (int i = 0; i < length; i++) {
+            tokIDs.put(tokens[i], null); // null is temporary placeholder value
+        }
+
+        // assign each token an ascending id
+        int _id = 1;
+        for (Entry<T, Integer> entry : tokIDs.entrySet()) {
+            entry.setValue(_id++);
+        }
+
+        // fill input array with ids
+        for (int i = 0; i < length; i++) {
+            input[i] = tokIDs.get(tokens[i]);
+        }
+
+        //System.out.println("Renaming tokens done.");
+
+        return delegate.buildSuffixArray(input, 0, length);
+    }
+}