Group reader/writer into format adapters

Author: sagebind

src/main/java/com/widen/tabitha/formats/FormatAdapter.java

@@ -0,0 +1,58 @@
+package com.widen.tabitha.formats;
+
+import com.widen.tabitha.reader.ReaderOptions;
+import com.widen.tabitha.reader.RowReader;
+import com.widen.tabitha.writer.RowWriter;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+/**
+ * Provides factory methods for creating readers and writers of a particular format.
+ */
+public interface FormatAdapter {
+    /**
+     * Create a row reader for a file at the given path.
+     *
+     * @param path The path of the file to read.
+     * @param options Options to pass to the reader.
+     * @return A new row reader.
+     * @throws IOException if an I/O error occurs.
+     */
+    default RowReader createReader(Path path, ReaderOptions options) throws IOException {
+        return createReader(Files.newInputStream(path), options);
+    }
+
+    /**
+     * Create a row reader for an input stream.
+     *
+     * @param inputStream The input stream to read.
+     * @param options Options to pass to the reader.
+     * @return A new row reader.
+     * @throws IOException if an I/O error occurs.
+     */
+    RowReader createReader(InputStream inputStream, ReaderOptions options) throws IOException;
+
+    /**
+     * Create a row writer that writes to the given path.
+     *
+     * @param path The path to write to.
+     * @return A new row writer.
+     * @throws IOException if an I/O error occurs.
+     */
+    default RowWriter createWriter(Path path) throws IOException {
+        return createWriter(Files.newOutputStream(path));
+    }
+
+    /**
+     * Create a row writer that writes to the given output stream.
+     *
+     * @param outputStream The output stream to write to.
+     * @return A new row writer.
+     * @throws IOException if an I/O error occurs.
+     */
+    RowWriter createWriter(OutputStream outputStream) throws IOException;
+}

src/main/java/com/widen/tabitha/formats/FormatRegistry.java

@@ -0,0 +1,110 @@
+package com.widen.tabitha.formats;
+
+import com.widen.tabitha.formats.delimited.DelimitedFormat;
+import com.widen.tabitha.formats.delimited.DelimitedRowReader;
+import com.widen.tabitha.formats.delimited.DelimitedRowWriter;
+import com.widen.tabitha.formats.excel.WorkbookRowWriter;
+import com.widen.tabitha.formats.excel.XLSRowReader;
+import com.widen.tabitha.formats.excel.XLSXRowReader;
+import com.widen.tabitha.reader.InlineHeaderReader;
+import com.widen.tabitha.reader.ReaderOptions;
+import com.widen.tabitha.reader.RowReader;
+import com.widen.tabitha.writer.RowWriter;
+import io.reactivex.Maybe;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.nio.file.Path;
+
+/**
+ * Manages the adapters for the file formats supported by Tabitha.
+ * <p>
+ * You probably want to use {@link com.widen.tabitha.reader.RowReaders} or {@link com.widen.tabitha.writer.RowWriter}
+ * instead.
+ */
+public class FormatRegistry {
+    /**
+     * Get a format factory for handling the given MIME type.
+     *
+     * @param mimeType The format MIME type.
+     * @return A format adapter, if one could be found.
+     */
+    public static Maybe<FormatAdapter> forMimeType(String mimeType) {
+        switch (mimeType) {
+            case "text/csv":
+            case "text/plain":
+                return Maybe.just(new FormatAdapter() {
+                    @Override
+                    public RowReader createReader(InputStream inputStream, ReaderOptions options) {
+                        return decorateReader(new DelimitedRowReader(inputStream, DelimitedFormat.CSV), options);
+                    }
+
+                    @Override
+                    public RowWriter createWriter(OutputStream outputStream) {
+                        return new DelimitedRowWriter(outputStream, DelimitedFormat.CSV);
+                    }
+                });
+
+            case "text/tab-separated-values":
+                return Maybe.just(new FormatAdapter() {
+                    @Override
+                    public RowReader createReader(InputStream inputStream, ReaderOptions options) {
+                        return decorateReader(new DelimitedRowReader(inputStream, DelimitedFormat.TSV), options);
+                    }
+
+                    @Override
+                    public RowWriter createWriter(OutputStream outputStream) {
+                        return new DelimitedRowWriter(outputStream, DelimitedFormat.TSV);
+                    }
+                });
+
+            case "application/vnd.ms-excel":
+                return Maybe.just(new FormatAdapter() {
+                    @Override
+                    public RowReader createReader(Path path, ReaderOptions options) throws IOException {
+                        return decorateReader(XLSRowReader.open(path, options), options);
+                    }
+
+                    @Override
+                    public RowReader createReader(InputStream inputStream, ReaderOptions options) throws IOException {
+                        return decorateReader(XLSRowReader.open(inputStream, options), options);
+                    }
+
+                    @Override
+                    public RowWriter createWriter(OutputStream outputStream) {
+                        return WorkbookRowWriter.xls(outputStream);
+                    }
+                });
+
+            case "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet":
+            case "application/x-tika-ooxml":
+                return Maybe.just(new FormatAdapter() {
+                    @Override
+                    public RowReader createReader(Path path, ReaderOptions options) throws IOException {
+                        return decorateReader(XLSXRowReader.open(path, options), options);
+                    }
+
+                    @Override
+                    public RowReader createReader(InputStream inputStream, ReaderOptions options) throws IOException {
+                        return decorateReader(XLSXRowReader.open(inputStream, options), options);
+                    }
+
+                    @Override
+                    public RowWriter createWriter(OutputStream outputStream) {
+                        return WorkbookRowWriter.xlsx(outputStream);
+                    }
+                });
+
+            default:
+                return Maybe.empty();
+        }
+    }
+
+    private static RowReader decorateReader(RowReader reader, ReaderOptions options) {
+        if (options.isInlineHeaders()) {
+            reader = new InlineHeaderReader(reader);
+        }
+        return reader;
+    }
+}

src/main/java/com/widen/tabitha/reader/Header.java

@@ -1,6 +1,12 @@
 package com.widen.tabitha.reader;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
 
 /**
  * Defines an ordered list of named columns.
@@ -182,5 +188,7 @@ public DuplicateColumnException(String column) {
     }
 
     @Override
-    public String toString() { return columnsByIndex.toString(); }
+    public String toString() {
+        return columnsByIndex.toString();
+    }
 }

src/main/java/com/widen/tabitha/reader/InlineHeaderReader.java

@@ -8,12 +8,12 @@
 /**
  * Decorates another reader, interpreting the first row of each page of data as the header for subsequent rows.
  */
-class InlineHeaderReader implements RowReader {
+public class InlineHeaderReader implements RowReader {
     private final RowReader inner;
     private Header currentHeader;
     private long currentPage = -1;
 
-    InlineHeaderReader(RowReader inner) {
+    public InlineHeaderReader(RowReader inner) {
         this.inner = inner;
     }
 

src/main/java/com/widen/tabitha/reader/RowReaders.java

@@ -1,18 +1,13 @@
 package com.widen.tabitha.reader;
 
-import com.widen.tabitha.formats.delimited.DelimitedFormat;
-import com.widen.tabitha.formats.delimited.DelimitedRowReader;
-import com.widen.tabitha.formats.excel.XLSRowReader;
-import com.widen.tabitha.formats.excel.XLSXRowReader;
+import com.widen.tabitha.formats.FormatRegistry;
+import io.reactivex.Maybe;
 import org.apache.tika.Tika;
 
 import java.io.BufferedInputStream;
-import java.io.IOException;
 import java.io.InputStream;
-import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
-import java.util.Optional;
 
 /**
  * Helper factory methods for creating row readers.
@@ -24,7 +19,7 @@ public class RowReaders {
      * @param path The file path of the file to open.
      * @return A row reader if the file is in a supported format.
      */
-    public static Optional<RowReader> open(String path) throws Exception {
+    public static Maybe<RowReader> open(String path) {
         return open(Paths.get(path), null);
     }
 
@@ -34,7 +29,7 @@ public static Optional<RowReader> open(String path) throws Exception {
      * @param path The file path of the file to open.
      * @return A row reader if the file is in a supported format.
      */
-    public static Optional<RowReader> open(Path path) throws Exception {
+    public static Maybe<RowReader> open(Path path) {
         return open(path, null);
     }
 
@@ -45,30 +40,11 @@ public static Optional<RowReader> open(Path path) throws Exception {
      * @param options Options to pass to the reader.
      * @return A row reader if the file is in a supported format.
      */
-    public static Optional<RowReader> open(Path path, ReaderOptions options) throws Exception {
-        if (options == null) {
-            options = new ReaderOptions();
-        }
-
-        String mimeType = tika.detect(path);
-
-        switch (mimeType) {
-            case "text/csv":
-            case "text/plain":
-                return Optional.of(decorate(new DelimitedRowReader(Files.newInputStream(path), DelimitedFormat.CSV), options));
-
-            case "text/tab-separated-values":
-                return Optional.of(decorate(new DelimitedRowReader(Files.newInputStream(path), DelimitedFormat.TSV), options));
-
-            case "application/vnd.ms-excel":
-                return Optional.of(decorate(XLSRowReader.open(path, options), options));
-
-            case "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet":
-            case "application/x-tika-ooxml":
-                return Optional.of(decorate(XLSXRowReader.open(path, options), options));
-        }
-
-        return Optional.empty();
+    public static Maybe<RowReader> open(Path path, ReaderOptions options) {
+        return Maybe
+            .fromCallable(() -> tika.detect(path))
+            .flatMap(FormatRegistry::forMimeType)
+            .map(formatAdapter -> formatAdapter.createReader(path, options != null ? options : new ReaderOptions()));
     }
 
     /**
@@ -77,7 +53,7 @@ public static Optional<RowReader> open(Path path, ReaderOptions options) throws
      * @param inputStream The input stream to read.
      * @return A row reader if the stream is in a supported format.
      */
-    public static Optional<RowReader> open(InputStream inputStream) throws IOException {
+    public static Maybe<RowReader> open(InputStream inputStream) {
         return open(inputStream, null, null);
     }
 
@@ -88,7 +64,7 @@ public static Optional<RowReader> open(InputStream inputStream) throws IOExcepti
      * @param filename The filename associated with the stream, if known.
      * @return A row reader if the stream is in a supported format.
      */
-    public static Optional<RowReader> open(InputStream inputStream, String filename) throws IOException {
+    public static Maybe<RowReader> open(InputStream inputStream, String filename) {
         return open(inputStream, filename, null);
     }
 
@@ -99,7 +75,7 @@ public static Optional<RowReader> open(InputStream inputStream, String filename)
      * @param options Options to pass to the reader.
      * @return A row reader if the stream is in a supported format.
      */
-    public static Optional<RowReader> open(InputStream inputStream, ReaderOptions options) throws IOException {
+    public static Maybe<RowReader> open(InputStream inputStream, ReaderOptions options) {
         return open(inputStream, null, options);
     }
 
@@ -111,44 +87,15 @@ public static Optional<RowReader> open(InputStream inputStream, ReaderOptions op
      * @param options Options to pass to the reader.
      * @return A row reader if the stream is in a supported format.
      */
-    public static Optional<RowReader> open(
-        InputStream inputStream,
-        String filename,
-        ReaderOptions options
-    ) throws IOException {
-        if (options == null) {
-            options = new ReaderOptions();
-        }
-
+    public static Maybe<RowReader> open(InputStream inputStream, String filename, ReaderOptions options) {
         // If our input stream supports marks, Tika will rewind the stream back to the start for us after detecting the
         // format, so ensure our input stream supports it.
-        inputStream = createRewindableInputStream(inputStream);
-        String mimeType = tika.detect(inputStream, filename);
-
-        switch (mimeType) {
-            case "text/csv":
-            case "text/plain":
-                return Optional.of(decorate(new DelimitedRowReader(inputStream, DelimitedFormat.CSV), options));
-
-            case "text/tab-separated-values":
-                return Optional.of(decorate(new DelimitedRowReader(inputStream, DelimitedFormat.TSV), options));
-
-            case "application/vnd.ms-excel":
-                return Optional.of(decorate(XLSRowReader.open(inputStream, options), options));
-
-            case "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet":
-            case "application/x-tika-ooxml":
-                return Optional.of(decorate(XLSXRowReader.open(inputStream, options), options));
-        }
-
-        return Optional.empty();
-    }
+        InputStream rewindableStream = createRewindableInputStream(inputStream);
 
-    private static RowReader decorate(RowReader reader, ReaderOptions options) {
-        if (options.isInlineHeaders()) {
-            reader = new InlineHeaderReader(reader);
-        }
-        return reader;
+        return Maybe
+            .fromCallable(() -> tika.detect(rewindableStream, filename))
+            .flatMap(FormatRegistry::forMimeType)
+            .map(formatAdapter -> formatAdapter.createReader(rewindableStream, options != null ? options : new ReaderOptions()));
     }
 
     private static InputStream createRewindableInputStream(InputStream inputStream) {