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SWHID.java
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SWHID.java
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package org.softwareheritage.graph;
import com.fasterxml.jackson.annotation.JsonValue;
import org.apache.commons.codec.DecoderException;
import org.apache.commons.codec.binary.Hex;
/**
* A Software Heritage persistent identifier (SWHID), see <a href=
* "https://docs.softwareheritage.org/devel/swh-model/persistent-identifiers.html#persistent-identifiers">persistent
* identifier documentation</a>.
*
* @author The Software Heritage developers
*/
public class SWHID {
/** Fixed hash length of the SWHID */
public static final int HASH_LENGTH = 40;
/** Full SWHID as a string */
String swhid;
/** SWHID node type */
Node.Type type;
/**
* Constructor.
*
* @param swhid full SWHID as a string
*/
public SWHID(String swhid) {
this.swhid = swhid;
// SWHID format: 'swh:1:type:hash'
String[] parts = swhid.split(":");
if (parts.length != 4 || !parts[0].equals("swh") || !parts[1].equals("1")) {
throw new IllegalArgumentException("malformed SWHID: " + swhid);
}
this.type = Node.Type.fromStr(parts[2]);
if (!parts[3].matches("[0-9a-f]{" + HASH_LENGTH + "}")) {
throw new IllegalArgumentException("malformed SWHID: " + swhid);
}
}
/**
* Creates a SWHID from a compact binary representation.
* <p>
* The binary format is specified in the Python module swh.graph.swhid:str_to_bytes .
*/
public static SWHID fromBytes(byte[] input) {
byte[] digest = new byte[20];
System.arraycopy(input, 2, digest, 0, digest.length);
String swhidStr = String.format("swh:%d:%s:%s", input[0], Node.Type.fromInt(input[1]).toString().toLowerCase(),
Hex.encodeHexString(digest));
return new SWHID(swhidStr);
}
@Override
public boolean equals(Object otherObj) {
if (otherObj == this)
return true;
if (!(otherObj instanceof SWHID))
return false;
SWHID other = (SWHID) otherObj;
return swhid.equals(other.getSWHID());
}
@Override
public int hashCode() {
return swhid.hashCode();
}
@Override
public String toString() {
return swhid;
}
/**
* Converts SWHID to a compact binary representation.
* <p>
* The binary format is specified in the Python module swh.graph.swhid:str_to_bytes .
*/
public byte[] toBytes() {
byte[] bytes = new byte[22];
byte[] digest;
bytes[0] = (byte) 1; // namespace version
bytes[1] = (byte) Node.Type.toInt(this.type); // SWHID type
try {
digest = Hex.decodeHex(this.swhid.substring(10)); // SHA1 hash
System.arraycopy(digest, 0, bytes, 2, digest.length);
} catch (DecoderException e) {
throw new IllegalArgumentException("invalid hex sequence in SWHID: " + this.swhid);
}
return bytes;
}
/**
* Returns full SWHID as a string.
*
* @return full SWHID string
*/
@JsonValue
public String getSWHID() {
return swhid;
}
/**
* Returns SWHID node type.
*
* @return SWHID corresponding {@link Node.Type}
* @see org.softwareheritage.graph.Node.Type
*/
public Node.Type getType() {
return type;
}
}

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