From 54a6331a87fbde2e0749c2ea12cf9319e87782b0 Mon Sep 17 00:00:00 2001
From: Randolf Richardson <randolf@richardson.tw>
Date: Wed, 16 Jan 2019 02:34:16 -0800
Subject: [PATCH] Added "separators" customization, NULL pre-checks, and
 Javadoc comment blocks to all constructors

Added a new Hashids constructor to support customized "separators" plus a pre-check for NULL that prevents a NullException by defaulting to DEFAULT_SEPS (this behaviour is modeled after the "salt" pre-check for NULL).

Added a pre-check for NULL for the custom "alphabet" that prevents a NullException by defaulting to DEFAULT_ALPHABET (this behaviour is also modeled after the "salt" pre-check for NULL).

Added rudimentary comments for existing constructors for better Javadoc output.  Added relevant details about the new constructor that supports custom "separators" (should this also be mentioned in the documentation on the web site?).
---
 src/main/java/org/hashids/Hashids.java | 39 +++++++++++++++++++++++++-
 1 file changed, 38 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/hashids/Hashids.java b/src/main/java/org/hashids/Hashids.java
index 6d688ea..49c30b4 100644
--- a/src/main/java/org/hashids/Hashids.java
+++ b/src/main/java/org/hashids/Hashids.java
@@ -15,6 +15,7 @@
  *
  * @author <a href="mailto:fanweixiao@gmail.com">fanweixiao</a>
  * @author <a href="mailto:terciofilho@gmail.com">Tercio Gaudencio Filho</a>
+ * @author <a href="mailto:randolf@richardson.tw">Randolf Richardson</a>
  * @since 0.3.3
  */
 public class Hashids {
@@ -38,21 +39,58 @@ public class Hashids {
   private final String seps;
   private final String guards;
 
+  /**
+   * Instantiate Hashids
+   */
   public Hashids() {
     this(DEFAULT_SALT);
   }
 
+  /**
+   * Instantiate Hashids
+   *
+   * @param salt (NULL defaults to "")
+   */
   public Hashids(String salt) {
     this(salt, 0);
   }
 
+  /**
+   * Instantiate Hashids
+   *
+   * @param salt (NULL defaults to "")
+   * @param minHashLength (0 is the default)
+   */
   public Hashids(String salt, int minHashLength) {
     this(salt, minHashLength, DEFAULT_ALPHABET);
   }
 
+  /**
+   * Instantiate Hashids
+   *
+   * @param salt (NULL defaults to "")
+   * @param minHashLength (0 is the default)
+   * @param alphabet (NULL defaults to "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890")
+   */
   public Hashids(String salt, int minHashLength, String alphabet) {
+    this(salt, minHashLength, DEFAULT_ALPHABET, DEFAULT_SEPS);
+  }
+
+  /**
+   * Instantiate Hashids
+   *
+   * Note: Specifiying separators (or none) that differ from the default will yield a different set of Hashids because separators-based character avoidance effects which characters can be used in encoding/decoding
+   *
+   * @param salt (NULL defaults to "")
+   * @param minHashLength (0 is the default)
+   * @param alphabet (NULL defaults to "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890")
+   * @param seps (NULL defaults to "cfhistuCFHISTU"; use "" to specify none)
+   */
+  public Hashids(String salt, int minHashLength, String alphabet, String seps) {
     this.salt = salt != null ? salt : DEFAULT_SALT;
     this.minHashLength = minHashLength > 0 ? minHashLength : DEFAULT_MIN_HASH_LENGTH;
+    if (alphabet == null) alphabet = DEFAULT_ALPHABET;
+    if (seps == null) seps = DEFAULT_SEPS;
 
     final StringBuilder uniqueAlphabet = new StringBuilder();
     for (int i = 0; i < alphabet.length(); i++) {
@@ -74,7 +112,6 @@ public Hashids(String salt, int minHashLength, String alphabet) {
 
     // seps should contain only characters present in alphabet;
     // alphabet should not contains seps
-    String seps = DEFAULT_SEPS;
     for (int i = 0; i < seps.length(); i++) {
       final int j = alphabet.indexOf(seps.charAt(i));
       if (j == -1) {