Merge pull request #3978 from TGIshib/key

Find by key on C# and Java (2)

java/com/google/flatbuffers/FlatBufferBuilder.java

@@ -389,6 +389,31 @@ public class FlatBufferBuilder {
         return copy;
     }
 
+   /**
+     * Create a vector of tables.
+     *
+     * @param offsets Offsets of the tables.
+     * @return Returns offset of the vector.
+     */
+    public int createVectorOfTables(int[] offsets) {
+        notNested();
+        startVector(Constants.SIZEOF_INT, offsets.length, Constants.SIZEOF_INT);
+        for(int i = offsets.length - 1; i >= 0; i--) addOffset(offsets[i]);
+        return endVector();
+    }
+
+    /**
+     * Create a vector of sorted by the key tables.
+     *
+     * @param obj Instance of the table subclass.
+     * @param offsets Offsets of the tables.
+     * @return Returns offset of the sorted vector.
+     */
+    public <T extends Table> int createSortedVectorOfTables(T obj, int[] offsets) {
+        obj.sortTables(offsets, bb);
+        return createVectorOfTables(offsets);
+    }
+	
    /**
     * Encode the string `s` in the buffer using UTF-8.  If {@code s} is
     * already a {@link CharBuffer}, this method is allocation free.

java/com/google/flatbuffers/Table.java

@@ -61,6 +61,11 @@ public class Table {
     return vtable_offset < bb.getShort(vtable) ? bb.getShort(vtable + vtable_offset) : 0;
   }
 
+  protected static int __offset(int vtable_offset, int offset, ByteBuffer bb) {
+    int vtable = bb.array().length - offset;
+    return bb.getShort(vtable + vtable_offset - bb.getInt(vtable)) + vtable;
+  }
+
   /**
    * Retrieve a relative offset.
    *
@@ -70,6 +75,10 @@ public class Table {
   protected int __indirect(int offset) {
     return offset + bb.getInt(offset);
   }
+  
+  protected static int __indirect(int offset, ByteBuffer bb) {
+    return offset + bb.getInt(offset);
+  }
 
   /**
    * Create a Java `String` from UTF-8 data stored inside the FlatBuffer.
@@ -188,6 +197,72 @@ public class Table {
     }
     return true;
   }
+  
+  /**
+   * Sort tables by the key.
+   *
+   * @param offsets An 'int' indexes of the tables into the bb.
+   * @param bb A {@code ByteBuffer} to get the tables.
+   */
+  protected void sortTables(int[] offsets, ByteBuffer bb) {
+    Integer[] off = new Integer[offsets.length];
+    for (int i = 0; i < offsets.length; i++) off[i] = offsets[i];
+    Arrays.sort(off, (Integer o1, Integer o2) -> keysCompare(o1, o2, bb));
+    for (int i = 0; i < offsets.length; i++) offsets[i] = off[i];
+  }
+
+  /**
+   * Compare two tables by the key.
+   *
+   * @param o1 An 'Integer' index of the first key into the bb.
+   * @param o2 An 'Integer' index of the second key into the bb.
+   * @param bb A {@code ByteBuffer} to get the keys.
+   */
+  protected int keysCompare(Integer o1, Integer o2, ByteBuffer bb) { return 0; }
+  
+  /**
+   * Compare two strings in the buffer.
+   *
+   * @param offset_1 An 'int' index of the first string into the bb.
+   * @param offset_2 An 'int' index of the second string into the bb.
+   * @param bb A {@code ByteBuffer} to get the strings.
+   */
+  protected static int compareStrings(int offset_1, int offset_2, ByteBuffer bb) {
+    offset_1 += bb.getInt(offset_1);
+    offset_2 += bb.getInt(offset_2);
+    int len_1 = bb.getInt(offset_1);
+    int len_2 = bb.getInt(offset_2);
+    int startPos_1 = offset_1 + SIZEOF_INT;
+    int startPos_2 = offset_2 + SIZEOF_INT;
+    int len = Math.min(len_1, len_2);
+    byte[] bbArray = bb.array();
+    for(int i = 0; i < len; i++) {
+      if (bbArray[i + startPos_1] != bbArray[i + startPos_2])
+        return bbArray[i + startPos_1] - bbArray[i + startPos_2];
+    }
+    return len_1 - len_2;
+  }
+  
+  /**
+   * Compare string from the buffer with the 'String' object.
+   *
+   * @param offset_1 An 'int' index of the first string into the bb.
+   * @param key Second string as a byte array.
+   * @param bb A {@code ByteBuffer} to get the first string.
+   */
+  protected static int compareStrings(int offset_1, byte[] key, ByteBuffer bb) {
+    offset_1 += bb.getInt(offset_1);
+    int len_1 = bb.getInt(offset_1);
+    int len_2 = key.length;
+    int startPos_1 = offset_1 + Constants.SIZEOF_INT;
+    int len = Math.min(len_1, len_2);
+    byte[] bbArray = bb.array();
+    for (int i = 0; i < len; i++) {
+      if (bbArray[i + startPos_1] != key[i])
+        return bbArray[i + startPos_1] - key[i];
+    }
+    return len_1 - len_2;
+  }
 }
 
 /// @endcond