ANTLR 4 Runtime 4.13.1 · org.antlr.v4.runtime.CharStreams

This class represents the primary interface for creating CharStreams from a variety of sources as of 4.7. The motivation was to support Unicode code points > U+FFFF. ANTLRInputStream and ANTLRFileStream are now deprecated in favor of the streams created by this interface. DEPRECATED: new ANTLRFileStream("myinputfile") NEW: CharStreams.fromFileName("myinputfile") WARNING: If you use both the deprecated and the new streams, you will see a nontrivial performance degradation. This speed hit is because the Lexer's internal code goes from a monomorphic to megamorphic dynamic dispatch to get characters from the input stream. Java's on-the-fly compiler (JIT) is unable to perform the same optimizations so stick with either the old or the new streams, if performance is a primary concern. See the extreme debugging and spelunking needed to identify this issue in our timing rig: https://github.com/antlr/antlr4/pull/1781 The ANTLR character streams still buffer all the input when you create the stream, as they have done for ~20 years. If you need unbuffered access, please note that it becomes challenging to create parse trees. The parse tree has to point to tokens which will either point into a stale location in an unbuffered stream or you have to copy the characters out of the buffer into the token. That defeats the purpose of unbuffered input. Per the ANTLR book, unbuffered streams are primarily useful for processing infinite streams *during the parse.* The new streams also use 8-bit buffers when possible so this new interface supports character streams that use half as much memory as the old ANTLRFileStream, which assumed 16-bit characters. A big shout out to Ben Hamilton (github bhamiltoncx) for his superhuman efforts across all targets to get true Unicode 3.1 support for U+10FFFF.

Modifier and Type	Field and Description
private static final int	DEFAULT_BUFFER_SIZE

Access	Constructor and Description
private	CharStreams()

Method Summary

Modifier and Type	Method and Description
public static CharStream	fromChannel(ReadableByteChannel channel) Creates a `CharStream` given an opened `ReadableByteChannel` containing UTF-8 bytes.
public static CharStream	fromChannel(ReadableByteChannel channel, Charset charset) Creates a `CharStream` given an opened `ReadableByteChannel` and the charset of the bytes contained in the channel.
public static CodePointCharStream	fromChannel(ReadableByteChannel channel, int bufferSize, CodingErrorAction decodingErrorAction, String sourceName) Creates a `CharStream` given an opened `ReadableByteChannel` containing UTF-8 bytes.
public static CodePointCharStream	fromChannel(ReadableByteChannel channel, Charset charset, int bufferSize, CodingErrorAction decodingErrorAction, String sourceName, long inputSize)
public static CharStream	fromFileName(String fileName) Creates a `CharStream` given a string containing a path to a UTF-8 file on disk.
public static CharStream	fromFileName(String fileName, Charset charset) Creates a `CharStream` given a string containing a path to a file on disk and the charset of the bytes contained in the file.
public static CharStream	fromPath(Path path) Creates a `CharStream` given a path to a UTF-8 encoded file on disk.
public static CharStream	fromPath(Path path, Charset charset) Creates a `CharStream` given a path to a file on disk and the charset of the bytes contained in the file.
public static CodePointCharStream	fromReader(Reader r) Creates a `CharStream` given a `Reader`.
public static CodePointCharStream	fromReader(Reader r, String sourceName) Creates a `CharStream` given a `Reader` and its source name.
public static CharStream	fromStream(InputStream is) Creates a `CharStream` given an opened `InputStream` containing UTF-8 bytes.
public static CharStream	fromStream(InputStream is, Charset charset) Creates a `CharStream` given an opened `InputStream` and the charset of the bytes contained in the stream.
public static CharStream	fromStream(InputStream is, Charset charset, long inputSize)
public static CodePointCharStream	fromString(String s) Creates a `CharStream` given a `String`.
public static CodePointCharStream	fromString(String s, String sourceName) Creates a `CharStream` given a `String` and the `sourceName` from which it came.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

DEFAULT_BUFFER_SIZE	back to summary
private static final int DEFAULT_BUFFER_SIZE

Constructor Detail

CharStreams	back to summary
private CharStreams()

Method Detail

fromChannel	back to summary
public static CharStream fromChannel(ReadableByteChannel channel) throws IOException Creates a `CharStream` given an opened `ReadableByteChannel` containing UTF-8 bytes. Reads the entire contents of the `channel` into the result before returning, then closes the `channel`.

fromChannel	back to summary
public static CharStream fromChannel(ReadableByteChannel channel, Charset charset) throws IOException Creates a `CharStream` given an opened `ReadableByteChannel` and the charset of the bytes contained in the channel. Reads the entire contents of the `channel` into the result before returning, then closes the `channel`.

fromChannel	back to summary
public static CodePointCharStream fromChannel(ReadableByteChannel channel, int bufferSize, CodingErrorAction decodingErrorAction, String sourceName) throws IOException Creates a `CharStream` given an opened `ReadableByteChannel` containing UTF-8 bytes. Reads the entire contents of the `channel` into the result before returning, then closes the `channel`.

fromChannel	back to summary
public static CodePointCharStream fromChannel(ReadableByteChannel channel, Charset charset, int bufferSize, CodingErrorAction decodingErrorAction, String sourceName, long inputSize) throws IOException

fromFileName	back to summary
public static CharStream fromFileName(String fileName) throws IOException Creates a `CharStream` given a string containing a path to a UTF-8 file on disk. Reads the entire contents of the file into the result before returning.

fromFileName	back to summary
public static CharStream fromFileName(String fileName, Charset charset) throws IOException Creates a `CharStream` given a string containing a path to a file on disk and the charset of the bytes contained in the file. Reads the entire contents of the file into the result before returning.

fromPath	back to summary
public static CharStream fromPath(Path path) throws IOException Creates a `CharStream` given a path to a UTF-8 encoded file on disk. Reads the entire contents of the file into the result before returning.

fromPath	back to summary
public static CharStream fromPath(Path path, Charset charset) throws IOException Creates a `CharStream` given a path to a file on disk and the charset of the bytes contained in the file. Reads the entire contents of the file into the result before returning.

fromReader	back to summary
public static CodePointCharStream fromReader(Reader r) throws IOException Creates a `CharStream` given a `Reader`. Closes the reader before returning.

fromReader	back to summary
public static CodePointCharStream fromReader(Reader r, String sourceName) throws IOException Creates a `CharStream` given a `Reader` and its source name. Closes the reader before returning.

fromStream	back to summary
public static CharStream fromStream(InputStream is) throws IOException Creates a `CharStream` given an opened `InputStream` containing UTF-8 bytes. Reads the entire contents of the `InputStream` into the result before returning, then closes the `InputStream`.

fromStream	back to summary
public static CharStream fromStream(InputStream is, Charset charset) throws IOException Creates a `CharStream` given an opened `InputStream` and the charset of the bytes contained in the stream. Reads the entire contents of the `InputStream` into the result before returning, then closes the `InputStream`.

fromStream	back to summary
public static CharStream fromStream(InputStream is, Charset charset, long inputSize) throws IOException

fromString	back to summary
public static CodePointCharStream fromString(String s) Creates a `CharStream` given a `String`.

fromString	back to summary
public static CodePointCharStream fromString(String s, String sourceName) Creates a `CharStream` given a `String` and the `sourceName` from which it came.

public final Class CharStreams

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Field Detail

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