Allow zip part mappers to drop entries

Author: Col-E

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>software.coley</groupId>
     <artifactId>lljzip</artifactId>
-    <version>2.0.0</version>
+    <version>2.1.0</version>
 
     <name>LL Java ZIP</name>
     <description>Lower level ZIP support for Java</description>

src/main/java/software/coley/lljzip/format/model/ZipArchive.java

@@ -46,8 +46,10 @@ public ZipArchive(@Nonnull Closeable closableBackingResource) {
 	@Nonnull
 	public ZipArchive withMapping(@Nonnull ZipPartMapper mapper) {
 		ZipArchive copy = new ZipArchive();
-		for (ZipPart part : parts)
-			copy.addPart(mapper.map(this, part));
+		for (ZipPart part : parts) {
+			ZipPart mappedPart = mapper.map(this, part);
+			if (mappedPart != null) copy.addPart(mappedPart);
+		}
 		return copy;
 	}
 

src/main/java/software/coley/lljzip/format/transform/CentralAdoptingMapper.java

@@ -5,6 +5,7 @@
 import software.coley.lljzip.format.model.ZipArchive;
 
 import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 
 /**
  * Patches {@link LocalFileHeader} to adopt {@link CentralDirectoryFileHeader} values.
@@ -20,7 +21,7 @@ public CentralAdoptingMapper(@Nonnull ZipPartMapper delegate) {
 		super(delegate);
 	}
 
-	@Nonnull
+	@Nullable
 	@Override
 	public LocalFileHeader mapLocal(@Nonnull ZipArchive archive, @Nonnull LocalFileHeader localFileHeader) {
 		if (localFileHeader.getLinkedDirectoryFileHeader() != null) {

src/main/java/software/coley/lljzip/format/transform/DelegatingZipPartMapper.java

@@ -6,6 +6,7 @@
 import software.coley.lljzip.format.model.ZipArchive;
 
 import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 
 /**
  * Zip part mapper that delegates to another mapper. Useful as a base to implement other mappers.
@@ -23,19 +24,19 @@ public DelegatingZipPartMapper(@Nonnull ZipPartMapper delegate) {
 		this.delegate = delegate;
 	}
 
-	@Nonnull
+	@Nullable
 	@Override
 	public LocalFileHeader mapLocal(@Nonnull ZipArchive archive, @Nonnull LocalFileHeader localFileHeader) {
 		return delegate.mapLocal(archive, localFileHeader);
 	}
 
-	@Nonnull
+	@Nullable
 	@Override
 	public CentralDirectoryFileHeader mapCentral(@Nonnull ZipArchive archive, @Nonnull CentralDirectoryFileHeader centralDirectoryFileHeader) {
 		return delegate.mapCentral(archive, centralDirectoryFileHeader);
 	}
 
-	@Nonnull
+	@Nullable
 	@Override
 	public EndOfCentralDirectory mapEnd(@Nonnull ZipArchive archive, @Nonnull EndOfCentralDirectory endOfCentralDirectory) {
 		return delegate.mapEnd(archive, endOfCentralDirectory);

src/main/java/software/coley/lljzip/format/transform/ZipPartMapper.java

@@ -3,6 +3,7 @@
 import software.coley.lljzip.format.model.*;
 
 import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 
 /**
  * Mapper outline for zip parts.
@@ -16,9 +17,9 @@ public interface ZipPartMapper {
 	 * @param part
 	 * 		Part to map.
 	 *
-	 * @return Mapped part.
+	 * @return Mapped part, or {@code null} on removal.
 	 */
-	@Nonnull
+	@Nullable
 	default ZipPart map(@Nonnull ZipArchive archive, @Nonnull ZipPart part) {
 		if (part instanceof LocalFileHeader) {
 			return mapLocal(archive, (LocalFileHeader) part);
@@ -37,9 +38,9 @@ default ZipPart map(@Nonnull ZipArchive archive, @Nonnull ZipPart part) {
 	 * @param localFileHeader
 	 * 		Original local file.
 	 *
-	 * @return Mapped local file.
+	 * @return Mapped local file, or {@code null} on removal.
 	 */
-	@Nonnull
+	@Nullable
 	LocalFileHeader mapLocal(@Nonnull ZipArchive archive, @Nonnull LocalFileHeader localFileHeader);
 
 	/**
@@ -48,9 +49,9 @@ default ZipPart map(@Nonnull ZipArchive archive, @Nonnull ZipPart part) {
 	 * @param centralDirectoryFileHeader
 	 * 		Original central directory file.
 	 *
-	 * @return Mapped central directory file.
+	 * @return Mapped central directory file, or {@code null} on removal.
 	 */
-	@Nonnull
+	@Nullable
 	CentralDirectoryFileHeader mapCentral(@Nonnull ZipArchive archive, @Nonnull CentralDirectoryFileHeader centralDirectoryFileHeader);
 
 	/**
@@ -59,8 +60,8 @@ default ZipPart map(@Nonnull ZipArchive archive, @Nonnull ZipPart part) {
 	 * @param endOfCentralDirectory
 	 * 		Original end.
 	 *
-	 * @return Mapped end.
+	 * @return Mapped end, or {@code null} on removal.
 	 */
-	@Nonnull
+	@Nullable
 	EndOfCentralDirectory mapEnd(@Nonnull ZipArchive archive, @Nonnull EndOfCentralDirectory endOfCentralDirectory);
 }