Abstract layer for Memo

src/main/java/org/stellar/base/Memo.java

@@ -1,18 +1,11 @@
 package org.stellar.base;
 
-import com.google.common.base.Strings;
 import org.apache.commons.codec.DecoderException;
-import org.apache.commons.codec.binary.Hex;
-import org.stellar.base.xdr.MemoType;
-import org.stellar.base.xdr.Uint64;
-
-import java.nio.charset.StandardCharsets;
-
-import static com.google.common.base.Preconditions.checkNotNull;
 
 /**
  * <p>The memo contains optional extra information. It is the responsibility of the client to interpret this value. Memos can be one of the following types:</p>
  * <ul>
+ * <li><code>MEMO_NONE</code>: Empty memo.</li>
  * <li><code>MEMO_TEXT</code>: A string up to 28-bytes long.</li>
  * <li><code>MEMO_ID</code>: A 64 bit unsigned integer.</li>
  * <li><code>MEMO_HASH</code>: A 32 byte hash.</li>
@@ -21,101 +14,63 @@
  * <p>Use static methods to generate any of above types.</p>
  * @see Transaction
  */
-public class Memo {
- Memo() {
- }
-
+public abstract class Memo {
  /**
- * Creates MEMO_NONE type memo.
+ * Creates new MemoNone instance.
  */
- public static org.stellar.base.xdr.Memo none() {
- org.stellar.base.xdr.Memo memo = new org.stellar.base.xdr.Memo();
- memo.setDiscriminant(MemoType.MEMO_NONE);
- return memo;
+ public static MemoNone none() {
+ return new MemoNone();
  }
 
  /**
- * Creates MEMO_TEXT type memo.
+ * Creates new {@link MemoText} instance.
  * @param text
  */
- public static org.stellar.base.xdr.Memo text(String text) {
- checkNotNull(text, "text cannot be null");
-
- int length = text.getBytes((StandardCharsets.UTF_8)).length;
- if (length > 28) {
- throw new MemoTooLongException("text must be <= 28 bytes. length=" + String.valueOf(length));
- }
-
- org.stellar.base.xdr.Memo memo = new org.stellar.base.xdr.Memo();
- memo.setDiscriminant(MemoType.MEMO_TEXT);
- memo.setText(text);
- return memo;
+ public static MemoText text(String text) {
+ return new MemoText(text);
  }
 
  /**
- * Creates MEMO_ID type memo.
+ * Creates new {@link MemoId} instance.
  * @param id
  */
- public static org.stellar.base.xdr.Memo id(long id) {
- org.stellar.base.xdr.Memo memo = new org.stellar.base.xdr.Memo();
- memo.setDiscriminant(MemoType.MEMO_ID);
- Uint64 idXdr = new Uint64();
- idXdr.setUint64(id);
- memo.setId(idXdr);
- return memo;
+ public static MemoId id(long id) {
+ return new MemoId(id);
  }
 
  /**
- * Creates MEMO_HASH type memo from byte array.
+ * Creates new {@link MemoHash} instance from byte array.
  * @param bytes
  */
- public static org.stellar.base.xdr.Memo hash(byte[] bytes) {
- org.stellar.base.xdr.Memo memo = new org.stellar.base.xdr.Memo();
- memo.setDiscriminant(MemoType.MEMO_HASH);
-
- if (bytes.length < 32) {
- bytes = Util.paddedByteArray(bytes, 32);
- } else if (bytes.length > 32) {
- throw new MemoTooLongException("Memo.hash can contain 32 bytes at max.");
- }
-
- org.stellar.base.xdr.Hash hash = new org.stellar.base.xdr.Hash();
- hash.setHash(bytes);
-
- memo.setHash(hash);
- return memo;
+ public static MemoHash hash(byte[] bytes) {
+ return new MemoHash(bytes);
  }
 
  /**
- * Creates MEMO_HASH type memo from hex-encoded string
+ * Creates new {@link MemoHash} instance from hex-encoded string
  * @param hexString
  * @throws DecoderException
  */
- public static org.stellar.base.xdr.Memo hash(String hexString) throws DecoderException {
- checkNotNull(hexString, "hexString cannot be null");
- byte[] decoded = Hex.decodeHex(hexString.toCharArray());
- return Memo.hash(decoded);
+ public static MemoHash hash(String hexString) throws DecoderException {
+ return new MemoHash(hexString);
  }
 
  /**
- * Creates MEMO_RETURN type memo from byte array.
+ * Creates new {@link MemoReturnHash} instance from byte array.
  * @param bytes
  */
- public static org.stellar.base.xdr.Memo returnHash(byte[] bytes) {
- org.stellar.base.xdr.Memo memo = Memo.hash(bytes);
- memo.setDiscriminant(MemoType.MEMO_RETURN);
- return memo;
+ public static MemoReturnHash returnHash(byte[] bytes) {
+ return new MemoReturnHash(bytes);
  }
 
  /**
- * Creates MEMO_RETURN type memo from hex-encoded string.
+ * Creates new {@link MemoReturnHash} instance from hex-encoded string.
  * @param hexString
  * @throws DecoderException
  */
- public static org.stellar.base.xdr.Memo returnHash(String hexString) throws DecoderException {
- checkNotNull(hexString, "hexString cannot be null");
- org.stellar.base.xdr.Memo memo = Memo.hash(hexString);
- memo.setDiscriminant(MemoType.MEMO_RETURN);
- return memo;
+ public static MemoReturnHash returnHash(String hexString) throws DecoderException {
+ return new MemoReturnHash(hexString);
  }
+
+ abstract org.stellar.base.xdr.Memo toXdr();
 }

src/main/java/org/stellar/base/MemoHash.java

@@ -0,0 +1,29 @@
+package org.stellar.base;
+
+import org.apache.commons.codec.DecoderException;
+import org.stellar.base.xdr.MemoType;
+
+/**
+ * Represents MEMO_HASH.
+ */
+public class MemoHash extends MemoHashAbstract {
+ public MemoHash(byte[] bytes) {
+ super(bytes);
+ }
+
+ public MemoHash(String hexString) throws DecoderException {
+ super(hexString);
+ }
+
+ @Override
+ org.stellar.base.xdr.Memo toXdr() {
+ org.stellar.base.xdr.Memo memo = new org.stellar.base.xdr.Memo();
+ memo.setDiscriminant(MemoType.MEMO_HASH);
+
+ org.stellar.base.xdr.Hash hash = new org.stellar.base.xdr.Hash();
+ hash.setHash(bytes);
+
+ memo.setHash(hash);
+ return memo;
+ }
+}

src/main/java/org/stellar/base/MemoHashAbstract.java

@@ -0,0 +1,60 @@
+package org.stellar.base;
+
+import org.apache.commons.codec.DecoderException;
+import org.apache.commons.codec.binary.Hex;
+
+abstract class MemoHashAbstract extends Memo {
+ protected byte[] bytes;
+
+ public MemoHashAbstract(byte[] bytes) {
+ if (bytes.length < 32) {
+ bytes = Util.paddedByteArray(bytes, 32);
+ } else if (bytes.length > 32) {
+ throw new MemoTooLongException("MEMO_HASH can contain 32 bytes at max.");
+ }
+
+ this.bytes = bytes;
+ }
+
+ public MemoHashAbstract(String hexString) throws DecoderException {
+ this(Hex.decodeHex(hexString.toCharArray()));
+ }
+
+ /**
+ * Returns 32 bytes long array contained in this memo.
+ */
+ public byte[] getBytes() {
+ return bytes;
+ }
+
+ /**
+ * <p>Returns hex representation of bytes contained in this memo.</p>
+ *
+ * <p>Example:</p>
+ * <code><pre>
+ * MemoHash memo = new MemoHash("4142434445");
+ * memo.getHexValue(); // 4142434445000000000000000000000000000000000000000000000000000000
+ * memo.getTrimmedHexValue(); // 4142434445
+ * </pre></code>
+ */
+ public String getHexValue() {
+ return new String(Hex.encodeHex(this.bytes));
+ }
+
+ /**
+ * <p>Returns hex representation of bytes contained in this memo until null byte (0x00) is found.</p>
+ *
+ * <p>Example:</p>
+ * <code><pre>
+ * MemoHash memo = new MemoHash("4142434445");
+ * memo.getHexValue(); // 4142434445000000000000000000000000000000000000000000000000000000
+ * memo.getTrimmedHexValue(); // 4142434445
+ * </pre></code>
+ */
+ public String getTrimmedHexValue() {
+ return this.getHexValue().split("00")[0];
+ }
+
+ @Override
+ abstract org.stellar.base.xdr.Memo toXdr();
+}

src/main/java/org/stellar/base/MemoId.java

@@ -0,0 +1,32 @@
+package org.stellar.base;
+
+import org.stellar.base.xdr.MemoType;
+import org.stellar.base.xdr.Uint64;
+
+/**
+ * Represents MEMO_ID.
+ */
+public class MemoId extends Memo {
+ private long id;
+
+ public MemoId(long id) {
+ if (id < 0) {
+ throw new IllegalArgumentException("id must be a positive number");
+ }
+ this.id = id;
+ }
+
+ public long getId() {
+ return id;
+ }
+
+ @Override
+ org.stellar.base.xdr.Memo toXdr() {
+ org.stellar.base.xdr.Memo memo = new org.stellar.base.xdr.Memo();
+ memo.setDiscriminant(MemoType.MEMO_ID);
+ Uint64 idXdr = new Uint64();
+ idXdr.setUint64(id);
+ memo.setId(idXdr);
+ return memo;
+ }
+}

src/main/java/org/stellar/base/MemoNone.java

@@ -0,0 +1,15 @@
+package org.stellar.base;
+
+import org.stellar.base.xdr.MemoType;
+
+/**
+ * Represents MEMO_NONE.
+ */
+public class MemoNone extends Memo {
+ @Override
+ org.stellar.base.xdr.Memo toXdr() {
+ org.stellar.base.xdr.Memo memo = new org.stellar.base.xdr.Memo();
+ memo.setDiscriminant(MemoType.MEMO_NONE);
+ return memo;
+ }
+}

src/main/java/org/stellar/base/MemoReturnHash.java

@@ -0,0 +1,30 @@
+package org.stellar.base;
+
+import org.apache.commons.codec.DecoderException;
+import org.stellar.base.xdr.Memo;
+import org.stellar.base.xdr.MemoType;
+
+/**
+ * Represents MEMO_RETURN.
+ */
+public class MemoReturnHash extends MemoHashAbstract {
+ public MemoReturnHash(byte[] bytes) {
+ super(bytes);
+ }
+
+ public MemoReturnHash(String hexString) throws DecoderException {
+ super(hexString);
+ }
+
+ @Override
+ Memo toXdr() {
+ org.stellar.base.xdr.Memo memo = new org.stellar.base.xdr.Memo();
+ memo.setDiscriminant(MemoType.MEMO_RETURN);
+
+ org.stellar.base.xdr.Hash hash = new org.stellar.base.xdr.Hash();
+ hash.setHash(bytes);
+
+ memo.setHash(hash);
+ return memo;
+ }
+}

src/main/java/org/stellar/base/MemoText.java

@@ -0,0 +1,35 @@
+package org.stellar.base;
+
+import org.stellar.base.xdr.MemoType;
+
+import java.nio.charset.StandardCharsets;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Represents MEMO_TEXT.
+ */
+public class MemoText extends Memo {
+ private String text;
+
+ public MemoText(String text) {
+ this.text = checkNotNull(text, "text cannot be null");
+
+ int length = text.getBytes((StandardCharsets.UTF_8)).length;
+ if (length > 28) {
+ throw new MemoTooLongException("text must be <= 28 bytes. length=" + String.valueOf(length));
+ }
+ }
+
+ public String getText() {
+ return text;
+ }
+
+ @Override
+ org.stellar.base.xdr.Memo toXdr() {
+ org.stellar.base.xdr.Memo memo = new org.stellar.base.xdr.Memo();
+ memo.setDiscriminant(MemoType.MEMO_TEXT);
+ memo.setText(text);
+ return memo;
+ }
+}

src/main/java/org/stellar/base/Operation.java

@@ -10,6 +10,9 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
+/**
+ * Abstract class for operations.
+ */
 public abstract class Operation {
  Operation() {}