/*
* Copyright (C) 2007 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.Closeable;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.StringReader;
import java.io.Writer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import com.google.common.annotations.Beta;
import com.google.common.base.Charsets;
import com.google.common.base.Function;
import com.google.common.collect.Iterables;
/**
* Provides utility methods for working with character streams.
*
* <p>
* All method parameters must be non-null unless documented otherwise.
*
* <p>
* Some of the methods in this class take arguments with a generic type of
* {@code Readable & Closeable}. A {@link java.io.Reader} implements both of
* those interfaces. Similarly for {@code Appendable & Closeable} and
* {@link java.io.Writer}.
*
* @author Chris Nokleberg
* @author Bin Zhu
* @author Colin Decker
* @since 1.0
*/
@Beta
public final class CharStreams {
private static final int BUF_SIZE = 0x800; // 2K chars (4K bytes)
private CharStreams() {
}
/**
* Returns a factory that will supply instances of {@link StringReader} that
* read a string value.
*
* @param value the string to read
* @return the factory
* @deprecated Use {@link CharSource#wrap(CharSequence)} instead. This method is
* scheduled for removal in Guava 18.0.
*/
@Deprecated
public static InputSupplier<StringReader> newReaderSupplier(final String value) {
return asInputSupplier(CharSource.wrap(value));
}
/**
* Returns a factory that will supply instances of {@link InputStreamReader},
* using the given {@link InputStream} factory and character set.
*
* @param in the factory that will be used to open input streams
* @param charset the charset used to decode the input stream; see
* {@link Charsets} for helpful predefined constants
* @return the factory
* @deprecated Use {@link ByteSource#asCharSource(Charset)} instead. This method
* is scheduled for removal in Guava 18.0.
*/
@Deprecated
public static InputSupplier<InputStreamReader> newReaderSupplier(final InputSupplier<? extends InputStream> in,
final Charset charset) {
return asInputSupplier(ByteStreams.asByteSource(in).asCharSource(charset));
}
/**
* Returns a factory that will supply instances of {@link OutputStreamWriter},
* using the given {@link OutputStream} factory and character set.
*
* @param out the factory that will be used to open output streams
* @param charset the charset used to encode the output stream; see
* {@link Charsets} for helpful predefined constants
* @return the factory
* @deprecated Use {@link ByteSink#asCharSink(Charset)} instead. This method is
* scheduled for removal in Guava 18.0.
*/
@Deprecated
public static OutputSupplier<OutputStreamWriter> newWriterSupplier(final OutputSupplier<? extends OutputStream> out,
final Charset charset) {
return asOutputSupplier(ByteStreams.asByteSink(out).asCharSink(charset));
}
/**
* Writes a character sequence (such as a string) to an appendable object from
* the given supplier.
*
* @param from the character sequence to write
* @param to the output supplier
* @throws IOException if an I/O error occurs
* @deprecated Use {@link CharSink#write(CharSequence)} instead. This method is
* scheduled for removal in Guava 18.0.
*/
@Deprecated
public static <W extends Appendable & Closeable> void write(CharSequence from, OutputSupplier<W> to)
throws IOException {
asCharSink(to).write(from);
}
/**
* Opens {@link Readable} and {@link Appendable} objects from the given
* factories, copies all characters between the two, and closes them.
*
* @param from the input factory
* @param to the output factory
* @return the number of characters copied
* @throws IOException if an I/O error occurs
* @deprecated Use {@link CharSource#copyTo(CharSink)} instead. This method is
* scheduled for removal in Guava 18.0.
*/
@Deprecated
public static <R extends Readable & Closeable, W extends Appendable & Closeable> long copy(InputSupplier<R> from,
OutputSupplier<W> to) throws IOException {
return asCharSource(from).copyTo(asCharSink(to));
}
/**
* Opens a {@link Readable} object from the supplier, copies all characters to
* the {@link Appendable} object, and closes the input. Does not close or flush
* the output.
*
* @param from the input factory
* @param to the object to write to
* @return the number of characters copied
* @throws IOException if an I/O error occurs
* @deprecated Use {@link CharSource#copyTo(Appendable)} instead. This method is
* scheduled for removal in Guava 18.0.
*/
@Deprecated
public static <R extends Readable & Closeable> long copy(InputSupplier<R> from, Appendable to) throws IOException {
return asCharSource(from).copyTo(to);
}
/**
* Copies all characters between the {@link Readable} and {@link Appendable}
* objects. Does not close or flush either object.
*
* @param from the object to read from
* @param to the object to write to
* @return the number of characters copied
* @throws IOException if an I/O error occurs
*/
public static long copy(Readable from, Appendable to) throws IOException {
checkNotNull(from);
checkNotNull(to);
CharBuffer buf = CharBuffer.allocate(BUF_SIZE);
long total = 0;
while (from.read(buf) != -1) {
buf.flip();
to.append(buf);
total += buf.remaining();
buf.clear();
}
return total;
}
/**
* Reads all characters from a {@link Readable} object into a {@link String}.
* Does not close the {@code Readable}.
*
* @param r the object to read from
* @return a string containing all the characters
* @throws IOException if an I/O error occurs
*/
public static String toString(Readable r) throws IOException {
return toStringBuilder(r).toString();
}
/**
* Returns the characters from a {@link Readable} & {@link Closeable} object
* supplied by a factory as a {@link String}.
*
* @param supplier the factory to read from
* @return a string containing all the characters
* @throws IOException if an I/O error occurs
* @deprecated Use {@link CharSource#read()} instead. This method is scheduled
* for removal in Guava 18.0.
*/
@Deprecated
public static <R extends Readable & Closeable> String toString(InputSupplier<R> supplier) throws IOException {
return asCharSource(supplier).read();
}
/**
* Reads all characters from a {@link Readable} object into a new
* {@link StringBuilder} instance. Does not close the {@code Readable}.
*
* @param r the object to read from
* @return a {@link StringBuilder} containing all the characters
* @throws IOException if an I/O error occurs
*/
private static StringBuilder toStringBuilder(Readable r) throws IOException {
StringBuilder sb = new StringBuilder();
copy(r, sb);
return sb;
}
/**
* Reads the first line from a {@link Readable} & {@link Closeable} object
* supplied by a factory. The line does not include line-termination characters,
* but does include other leading and trailing whitespace.
*
* @param supplier the factory to read from
* @return the first line, or null if the reader is empty
* @throws IOException if an I/O error occurs
* @deprecated Use {@link CharSource#readFirstLine()} instead. This method is
* scheduled for removal in Guava 18.0.
*/
@Deprecated
public static <R extends Readable & Closeable> String readFirstLine(InputSupplier<R> supplier) throws IOException {
return asCharSource(supplier).readFirstLine();
}
/**
* Reads all of the lines from a {@link Readable} & {@link Closeable} object
* supplied by a factory. The lines do not include line-termination characters,
* but do include other leading and trailing whitespace.
*
* @param supplier the factory to read from
* @return a mutable {@link List} containing all the lines
* @throws IOException if an I/O error occurs
* @deprecated Use {@link CharSource#readLines()} instead, but note that it
* returns an {@code ImmutableList}. This method is scheduled for
* removal in Guava 18.0.
*/
@Deprecated
public static <R extends Readable & Closeable> List<String> readLines(InputSupplier<R> supplier)
throws IOException {
Closer closer = Closer.create();
try {
R r = closer.register(supplier.getInput());
return readLines(r);
} catch (Throwable e) {
throw closer.rethrow(e);
} finally {
closer.close();
}
}
/**
* Reads all of the lines from a {@link Readable} object. The lines do not
* include line-termination characters, but do include other leading and
* trailing whitespace.
*
* <p>
* Does not close the {@code Readable}. If reading files or resources you should
* use the {@link Files#readLines} and {@link Resources#readLines} methods.
*
* @param r the object to read from
* @return a mutable {@link List} containing all the lines
* @throws IOException if an I/O error occurs
*/
public static List<String> readLines(Readable r) throws IOException {
List<String> result = new ArrayList<String>();
LineReader lineReader = new LineReader(r);
String line;
while ((line = lineReader.readLine()) != null) {
result.add(line);
}
return result;
}
/**
* Streams lines from a {@link Readable} object, stopping when the processor
* returns {@code false} or all lines have been read and returning the result
* produced by the processor. Does not close {@code readable}. Note that this
* method may not fully consume the contents of {@code readable} if the
* processor stops processing early.
*
* @throws IOException if an I/O error occurs
* @since 14.0
*/
public static <T> T readLines(Readable readable, LineProcessor<T> processor) throws IOException {
checkNotNull(readable);
checkNotNull(processor);
LineReader lineReader = new LineReader(readable);
String line;
while ((line = lineReader.readLine()) != null) {
if (!processor.processLine(line)) {
break;
}
}
return processor.getResult();
}
/**
* Streams lines from a {@link Readable} and {@link Closeable} object supplied
* by a factory, stopping when our callback returns false, or we have read all
* of the lines.
*
* @param supplier the factory to read from
* @param callback the LineProcessor to use to handle the lines
* @return the output of processing the lines
* @throws IOException if an I/O error occurs
* @deprecated Use {@link CharSource#readLines(LineProcessor)} instead. This
* method is scheduled for removal in Guava 18.0.
*/
@Deprecated
public static <R extends Readable & Closeable, T> T readLines(InputSupplier<R> supplier, LineProcessor<T> callback)
throws IOException {
checkNotNull(supplier);
checkNotNull(callback);
Closer closer = Closer.create();
try {
R r = closer.register(supplier.getInput());
return readLines(r, callback);
} catch (Throwable e) {
throw closer.rethrow(e);
} finally {
closer.close();
}
}
/**
* Joins multiple {@link Reader} suppliers into a single supplier. Reader
* returned from the supplier will contain the concatenated data from the
* readers of the underlying suppliers.
*
* <p>
* Reading from the joined reader will throw a {@link NullPointerException} if
* any of the suppliers are null or return null.
*
* <p>
* Only one underlying reader will be open at a time. Closing the joined reader
* will close the open underlying reader.
*
* @param suppliers the suppliers to concatenate
* @return a supplier that will return a reader containing the concatenated data
* @deprecated Use {@link CharSource#concat(Iterable)} instead. This method is
* scheduled for removal in Guava 18.0.
*/
@Deprecated
public static InputSupplier<Reader> join(final Iterable<? extends InputSupplier<? extends Reader>> suppliers) {
checkNotNull(suppliers);
Iterable<CharSource> sources = Iterables.transform(suppliers,
new Function<InputSupplier<? extends Reader>, CharSource>() {
@Override
public CharSource apply(InputSupplier<? extends Reader> input) {
return asCharSource(input);
}
});
return asInputSupplier(CharSource.concat(sources));
}
/**
* Varargs form of {@link #join(Iterable)}.
*
* @deprecated Use {@link CharSource#concat(CharSource[])} instead. This method
* is scheduled for removal in Guava 18.0.
*/
@Deprecated
@SuppressWarnings("unchecked") // suppress "possible heap pollution" warning in JDK7
public static InputSupplier<Reader> join(InputSupplier<? extends Reader>... suppliers) {
return join(Arrays.asList(suppliers));
}
/**
* Discards {@code n} characters of data from the reader. This method will block
* until the full amount has been skipped. Does not close the reader.
*
* @param reader the reader to read from
* @param n the number of characters to skip
* @throws EOFException if this stream reaches the end before skipping all the
* characters
* @throws IOException if an I/O error occurs
*/
public static void skipFully(Reader reader, long n) throws IOException {
checkNotNull(reader);
while (n > 0) {
long amt = reader.skip(n);
if (amt == 0) {
// force a blocking read
if (reader.read() == -1) {
throw new EOFException();
}
n--;
} else {
n -= amt;
}
}
}
/**
* Returns a {@link Writer} that simply discards written chars.
*
* @since 15.0
*/
public static Writer nullWriter() {
return NullWriter.INSTANCE;
}
private static final class NullWriter extends Writer {
private static final NullWriter INSTANCE = new NullWriter();
@Override
public void write(int c) {
}
@Override
public void write(char[] cbuf) {
checkNotNull(cbuf);
}
@Override
public void write(char[] cbuf, int off, int len) {
checkPositionIndexes(off, off + len, cbuf.length);
}
@Override
public void write(String str) {
checkNotNull(str);
}
@Override
public void write(String str, int off, int len) {
checkPositionIndexes(off, off + len, str.length());
}
@Override
public Writer append(CharSequence csq) {
checkNotNull(csq);
return this;
}
@Override
public Writer append(CharSequence csq, int start, int end) {
checkPositionIndexes(start, end, csq.length());
return this;
}
@Override
public Writer append(char c) {
return this;
}
@Override
public void flush() {
}
@Override
public void close() {
}
@Override
public String toString() {
return "CharStreams.nullWriter()";
}
}
/**
* Returns a Writer that sends all output to the given {@link Appendable}
* target. Closing the writer will close the target if it is {@link Closeable},
* and flushing the writer will flush the target if it is
* {@link java.io.Flushable}.
*
* @param target the object to which output will be sent
* @return a new Writer object, unless target is a Writer, in which case the
* target is returned
*/
public static Writer asWriter(Appendable target) {
if (target instanceof Writer) {
return (Writer) target;
}
return new AppendableWriter(target);
}
// TODO(user): Remove these once Input/OutputSupplier methods are removed
static Reader asReader(final Readable readable) {
checkNotNull(readable);
if (readable instanceof Reader) {
return (Reader) readable;
}
return new Reader() {
@Override
public int read(char[] cbuf, int off, int len) throws IOException {
return read(CharBuffer.wrap(cbuf, off, len));
}
@Override
public int read(CharBuffer target) throws IOException {
return readable.read(target);
}
@Override
public void close() throws IOException {
if (readable instanceof Closeable) {
((Closeable) readable).close();
}
}
};
}
/**
* Returns a view of the given {@code Readable} supplier as a
* {@code CharSource}.
*
* <p>
* This method is a temporary method provided for easing migration from
* suppliers to sources and sinks.
*
* @since 15.0
* @deprecated Convert all {@code InputSupplier<? extends Readable>}
* implementations to extend {@link CharSource} or provide a method
* for viewing the object as a {@code CharSource}. This method is
* scheduled for removal in Guava 18.0.
*/
@Deprecated
public static CharSource asCharSource(final InputSupplier<? extends Readable> supplier) {
checkNotNull(supplier);
return new CharSource() {
@Override
public Reader openStream() throws IOException {
return asReader(supplier.getInput());
}
@Override
public String toString() {
return "CharStreams.asCharSource(" + supplier + ")";
}
};
}
/**
* Returns a view of the given {@code Appendable} supplier as a
* {@code CharSink}.
*
* <p>
* This method is a temporary method provided for easing migration from
* suppliers to sources and sinks.
*
* @since 15.0
* @deprecated Convert all {@code OutputSupplier<? extends Appendable>}
* implementations to extend {@link CharSink} or provide a method
* for viewing the object as a {@code CharSink}. This method is
* scheduled for removal in Guava 18.0.
*/
@Deprecated
public static CharSink asCharSink(final OutputSupplier<? extends Appendable> supplier) {
checkNotNull(supplier);
return new CharSink() {
@Override
public Writer openStream() throws IOException {
return asWriter(supplier.getOutput());
}
@Override
public String toString() {
return "CharStreams.asCharSink(" + supplier + ")";
}
};
}
@SuppressWarnings("unchecked") // used internally where known to be safe
static <R extends Reader> InputSupplier<R> asInputSupplier(CharSource source) {
return (InputSupplier) checkNotNull(source);
}
@SuppressWarnings("unchecked") // used internally where known to be safe
static <W extends Writer> OutputSupplier<W> asOutputSupplier(CharSink sink) {
return (OutputSupplier) checkNotNull(sink);
}
}