antlr4ts
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ANTLR 4 runtime for JavaScript written in Typescript
133 lines • 6.33 kB
JavaScript
;
/*!
* Copyright 2016 The ANTLR Project. All rights reserved.
* Licensed under the BSD-3-Clause license. See LICENSE file in the project root for license information.
*/
Object.defineProperty(exports, "__esModule", { value: true });
exports.CharStreams = void 0;
const CodePointBuffer_1 = require("./CodePointBuffer");
const CodePointCharStream_1 = require("./CodePointCharStream");
const IntStream_1 = require("./IntStream");
// const DEFAULT_BUFFER_SIZE: number = 4096;
/** This class represents the primary interface for creating {@link CharStream}s
* from a variety of sources as of 4.7. The motivation was to support
* Unicode code points > U+FFFF. {@link ANTLRInputStream} and
* {@link ANTLRFileStream} are now deprecated in favor of the streams created
* by this interface.
*
* DEPRECATED: {@code new ANTLRFileStream("myinputfile")}
* NEW: {@code 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
* {@link 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 {@link 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
*/
var CharStreams;
(function (CharStreams) {
// /**
// * Creates a {@link CharStream} given a path to a UTF-8
// * encoded file on disk.
// *
// * Reads the entire contents of the file into the result before returning.
// */
// export function fromFile(file: File): CharStream;
// export function fromFile(file: File, charset: Charset): CharStream;
// export function fromFile(file: File, charset?: Charset): CharStream {
// if (charset === undefined) {
// charset = Charset.forName("UTF-8");
// }
function fromString(s, sourceName) {
if (sourceName === undefined || sourceName.length === 0) {
sourceName = IntStream_1.IntStream.UNKNOWN_SOURCE_NAME;
}
// Initial guess assumes no code points > U+FFFF: one code
// point for each code unit in the string
let codePointBufferBuilder = CodePointBuffer_1.CodePointBuffer.builder(s.length);
// TODO: CharBuffer.wrap(String) rightfully returns a read-only buffer
// which doesn't expose its array, so we make a copy.
let cb = new Uint16Array(s.length);
for (let i = 0; i < s.length; i++) {
cb[i] = s.charCodeAt(i);
}
codePointBufferBuilder.append(cb);
return CodePointCharStream_1.CodePointCharStream.fromBuffer(codePointBufferBuilder.build(), sourceName);
}
CharStreams.fromString = fromString;
// export function bufferFromChannel(
// channel: ReadableByteChannel,
// charset: Charset,
// bufferSize: number,
// decodingErrorAction: CodingErrorAction,
// inputSize: number): CodePointBuffer {
// try {
// let utf8BytesIn: Uint8Array = new Uint8Array(bufferSize);
// let utf16CodeUnitsOut: Uint16Array = new Uint16Array(bufferSize);
// if (inputSize === -1) {
// inputSize = bufferSize;
// } else if (inputSize > Integer.MAX_VALUE) {
// // ByteBuffer et al don't support long sizes
// throw new RangeError(`inputSize ${inputSize} larger than max ${Integer.MAX_VALUE}`);
// }
// let codePointBufferBuilder: CodePointBuffer.Builder = CodePointBuffer.builder(inputSize);
// let decoder: CharsetDecoder = charset
// .newDecoder()
// .onMalformedInput(decodingErrorAction)
// .onUnmappableCharacter(decodingErrorAction);
// let endOfInput: boolean = false;
// while (!endOfInput) {
// let bytesRead: number = channel.read(utf8BytesIn);
// endOfInput = (bytesRead === -1);
// utf8BytesIn.flip();
// let result: CoderResult = decoder.decode(
// utf8BytesIn,
// utf16CodeUnitsOut,
// endOfInput);
// if (result.isError() && decodingErrorAction === CodingErrorAction.REPORT) {
// result.throwException();
// }
// utf16CodeUnitsOut.flip();
// codePointBufferBuilder.append(utf16CodeUnitsOut);
// utf8BytesIn.compact();
// utf16CodeUnitsOut.compact();
// }
// // Handle any bytes at the end of the file which need to
// // be represented as errors or substitution characters.
// let flushResult: CoderResult = decoder.flush(utf16CodeUnitsOut);
// if (flushResult.isError() && decodingErrorAction === CodingErrorAction.REPORT) {
// flushResult.throwException();
// }
// utf16CodeUnitsOut.flip();
// codePointBufferBuilder.append(utf16CodeUnitsOut);
// return codePointBufferBuilder.build();
// }
// finally {
// channel.close();
// }
// }
})(CharStreams = exports.CharStreams || (exports.CharStreams = {}));
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