Update #0 - First Release

sources/main/java/com/google/common/io/GwtWorkarounds.java

@@ -0,0 +1,241 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.google.common.io;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.base.Preconditions.checkPositionIndexes;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.Reader;
+import java.io.Writer;
+
+import com.google.common.annotations.GwtCompatible;
+import com.google.common.annotations.GwtIncompatible;
+
+/**
+ * Provides simple GWT-compatible substitutes for {@code InputStream},
+ * {@code OutputStream}, {@code Reader}, and {@code Writer} so that
+ * {@code BaseEncoding} can use streaming implementations while remaining
+ * GWT-compatible.
+ *
+ * @author Louis Wasserman
+ */
+@GwtCompatible(emulated = true)
+final class GwtWorkarounds {
+	private GwtWorkarounds() {
+	}
+
+	/**
+	 * A GWT-compatible substitute for a {@code Reader}.
+	 */
+	interface CharInput {
+		int read() throws IOException;
+
+		void close() throws IOException;
+	}
+
+	/**
+	 * Views a {@code Reader} as a {@code CharInput}.
+	 */
+	@GwtIncompatible("Reader")
+	static CharInput asCharInput(final Reader reader) {
+		checkNotNull(reader);
+		return new CharInput() {
+			@Override
+			public int read() throws IOException {
+				return reader.read();
+			}
+
+			@Override
+			public void close() throws IOException {
+				reader.close();
+			}
+		};
+	}
+
+	/**
+	 * Views a {@code CharSequence} as a {@code CharInput}.
+	 */
+	static CharInput asCharInput(final CharSequence chars) {
+		checkNotNull(chars);
+		return new CharInput() {
+			int index = 0;
+
+			@Override
+			public int read() {
+				if (index < chars.length()) {
+					return chars.charAt(index++);
+				} else {
+					return -1;
+				}
+			}
+
+			@Override
+			public void close() {
+				index = chars.length();
+			}
+		};
+	}
+
+	/**
+	 * A GWT-compatible substitute for an {@code InputStream}.
+	 */
+	interface ByteInput {
+		int read() throws IOException;
+
+		void close() throws IOException;
+	}
+
+	/**
+	 * Views a {@code ByteInput} as an {@code InputStream}.
+	 */
+	@GwtIncompatible("InputStream")
+	static InputStream asInputStream(final ByteInput input) {
+		checkNotNull(input);
+		return new InputStream() {
+			@Override
+			public int read() throws IOException {
+				return input.read();
+			}
+
+			@Override
+			public int read(byte[] b, int off, int len) throws IOException {
+				checkNotNull(b);
+				checkPositionIndexes(off, off + len, b.length);
+				if (len == 0) {
+					return 0;
+				}
+				int firstByte = read();
+				if (firstByte == -1) {
+					return -1;
+				}
+				b[off] = (byte) firstByte;
+				for (int dst = 1; dst < len; dst++) {
+					int readByte = read();
+					if (readByte == -1) {
+						return dst;
+					}
+					b[off + dst] = (byte) readByte;
+				}
+				return len;
+			}
+
+			@Override
+			public void close() throws IOException {
+				input.close();
+			}
+		};
+	}
+
+	/**
+	 * A GWT-compatible substitute for an {@code OutputStream}.
+	 */
+	interface ByteOutput {
+		void write(byte b) throws IOException;
+
+		void flush() throws IOException;
+
+		void close() throws IOException;
+	}
+
+	/**
+	 * Views a {@code ByteOutput} as an {@code OutputStream}.
+	 */
+	@GwtIncompatible("OutputStream")
+	static OutputStream asOutputStream(final ByteOutput output) {
+		checkNotNull(output);
+		return new OutputStream() {
+			@Override
+			public void write(int b) throws IOException {
+				output.write((byte) b);
+			}
+
+			@Override
+			public void flush() throws IOException {
+				output.flush();
+			}
+
+			@Override
+			public void close() throws IOException {
+				output.close();
+			}
+		};
+	}
+
+	/**
+	 * A GWT-compatible substitute for a {@code Writer}.
+	 */
+	interface CharOutput {
+		void write(char c) throws IOException;
+
+		void flush() throws IOException;
+
+		void close() throws IOException;
+	}
+
+	/**
+	 * Views a {@code Writer} as a {@code CharOutput}.
+	 */
+	@GwtIncompatible("Writer")
+	static CharOutput asCharOutput(final Writer writer) {
+		checkNotNull(writer);
+		return new CharOutput() {
+			@Override
+			public void write(char c) throws IOException {
+				writer.append(c);
+			}
+
+			@Override
+			public void flush() throws IOException {
+				writer.flush();
+			}
+
+			@Override
+			public void close() throws IOException {
+				writer.close();
+			}
+		};
+	}
+
+	/**
+	 * Returns a {@code CharOutput} whose {@code toString()} method can be used to
+	 * get the combined output.
+	 */
+	static CharOutput stringBuilderOutput(int initialSize) {
+		final StringBuilder builder = new StringBuilder(initialSize);
+		return new CharOutput() {
+
+			@Override
+			public void write(char c) {
+				builder.append(c);
+			}
+
+			@Override
+			public void flush() {
+			}
+
+			@Override
+			public void close() {
+			}
+
+			@Override
+			public String toString() {
+				return builder.toString();
+			}
+		};
+	}
+}