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The ANTLR 4 grammar compiler.
CharStreams (ANTLR 4 Runtime (Optimized) 4.7.3 API)
org.antlr.v4.runtime
Enum CharStreams
- java.lang.Object
-
- java.lang.Enum<CharStreams>
-
- org.antlr.v4.runtime.CharStreams
-
- All Implemented Interfaces:
- Serializable, Comparable<CharStreams>
public enum CharStreams
extends Enum<CharStreams>
This class represents the primary interface for creating CharStream
s
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.
- Since:
- 4.7
-
-
Method Summary
Methods
Modifier and Type
Method and Description
static CodePointBuffer
bufferFromChannel(ReadableByteChannel channel,
Charset charset,
int bufferSize,
CodingErrorAction decodingErrorAction,
long inputSize)
static CharStream
fromChannel(ReadableByteChannel channel)
Creates a CharStream
given an opened ReadableByteChannel
containing UTF-8 bytes.
static CharStream
fromChannel(ReadableByteChannel channel,
Charset charset)
Creates a CharStream
given an opened ReadableByteChannel
and the
charset of the bytes contained in the channel.
static CodePointCharStream
fromChannel(ReadableByteChannel channel,
Charset charset,
int bufferSize,
CodingErrorAction decodingErrorAction,
String sourceName,
long inputSize)
static CodePointCharStream
fromChannel(ReadableByteChannel channel,
int bufferSize,
CodingErrorAction decodingErrorAction,
String sourceName)
Creates a CharStream
given an opened ReadableByteChannel
containing UTF-8 bytes.
static CharStream
fromFile(File file)
Creates a CharStream
given a path to a UTF-8
encoded file on disk.
static CharStream
fromFile(File file,
Charset charset)
Creates a CharStream
given a path to a file on disk and the
charset of the bytes contained in the file.
static CharStream
fromFileName(String fileName)
Creates a CharStream
given a string containing a
path to a UTF-8 file on disk.
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.
static CodePointCharStream
fromReader(Reader r)
Creates a CharStream
given a Reader
.
static CodePointCharStream
fromReader(Reader r,
String sourceName)
Creates a CharStream
given a Reader
and its
source name.
static CharStream
fromStream(InputStream is)
Creates a CharStream
given an opened InputStream
containing UTF-8 bytes.
static CharStream
fromStream(InputStream is,
Charset charset)
Creates a CharStream
given an opened InputStream
and the
charset of the bytes contained in the stream.
static CharStream
fromStream(InputStream is,
Charset charset,
String sourceName,
long inputSize)
static CodePointCharStream
fromString(String s)
Creates a CharStream
given a String
.
static CodePointCharStream
fromString(String s,
String sourceName)
static CharStreams
valueOf(String name)
Returns the enum constant of this type with the specified name.
static CharStreams[]
values()
Returns an array containing the constants of this enum type, in
the order they are declared.
-
-
Method Detail
-
values
public static CharStreams[] values()
Returns an array containing the constants of this enum type, in
the order they are declared. This method may be used to iterate
over the constants as follows:
for (CharStreams c : CharStreams.values())
System.out.println(c);
- Returns:
- an array containing the constants of this enum type, in
the order they are declared
-
valueOf
public static CharStreams valueOf(String name)
Returns the enum constant of this type with the specified name.
The string must match exactly an identifier used to declare an
enum constant in this type. (Extraneous whitespace characters are
not permitted.)
- Parameters:
name
- the name of the enum constant to be returned.
- Returns:
- the enum constant with the specified name
- Throws:
IllegalArgumentException
- if this enum type has no constant
with the specified name
NullPointerException
- if the argument is null
-
fromFile
public static CharStream fromFile(File file)
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.
- Throws:
IOException
-
fromFile
public static CharStream fromFile(File file,
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.
- Throws:
IOException
-
fromFileName
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.
- Throws:
IOException
-
fromFileName
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.
- Throws:
IOException
-
fromStream
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
.
- Throws:
IOException
-
fromStream
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
.
- Throws:
IOException
-
fromStream
public static CharStream fromStream(InputStream is,
Charset charset,
String sourceName,
long inputSize)
throws IOException
- Throws:
IOException
-
fromChannel
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
.
- Throws:
IOException
-
fromChannel
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
.
- Throws:
IOException
-
fromReader
public static CodePointCharStream fromReader(Reader r)
throws IOException
Creates a CharStream
given a Reader
. Closes
the reader before returning.
- Throws:
IOException
-
fromReader
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.
- Throws:
IOException
-
fromString
public static CodePointCharStream fromString(String s)
Creates a CharStream
given a String
.
-
fromString
public static CodePointCharStream fromString(String s,
String sourceName)
-
fromChannel
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
.
- Throws:
IOException
-
fromChannel
public static CodePointCharStream fromChannel(ReadableByteChannel channel,
Charset charset,
int bufferSize,
CodingErrorAction decodingErrorAction,
String sourceName,
long inputSize)
throws IOException
- Throws:
IOException
-
bufferFromChannel
public static CodePointBuffer bufferFromChannel(ReadableByteChannel channel,
Charset charset,
int bufferSize,
CodingErrorAction decodingErrorAction,
long inputSize)
throws IOException
- Throws:
IOException
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