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Convert src/core/decode_stream.js to use standard classes

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This commit is contained in:
Jonas Jenwald 2021-04-27 16:31:03 +02:00
parent 8ce2cae4a7
commit b11f012e52
1 changed files with 160 additions and 163 deletions
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323
src/core/decode_stream.js
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@ -16,16 +16,15 @@
import { Stream } from "./stream.js"; import { Stream } from "./stream.js";
import { unreachable } from "../shared/util.js"; import { unreachable } from "../shared/util.js";
// super class for the decoding streams // Lots of DecodeStreams are created whose buffers are never used. For these
const DecodeStream = (function DecodeStreamClosure() { // we share a single empty buffer. This is (a) space-efficient and (b) avoids
// Lots of DecodeStreams are created whose buffers are never used. For these // having special cases that would be required if we used |null| for an empty
// we share a single empty buffer. This is (a) space-efficient and (b) avoids // buffer.
// having special cases that would be required if we used |null| for an empty const emptyBuffer = new Uint8Array(0);
// buffer.
const emptyBuffer = new Uint8Array(0);
// eslint-disable-next-line no-shadow // Super class for the decoding streams.
function DecodeStream(maybeMinBufferLength) { class DecodeStream {
constructor(maybeMinBufferLength) {
this._rawMinBufferLength = maybeMinBufferLength || 0; this._rawMinBufferLength = maybeMinBufferLength || 0;
this.pos = 0; this.pos = 0;
@ -41,155 +40,156 @@ const DecodeStream = (function DecodeStreamClosure() {
} }
} }
DecodeStream.prototype = { // eslint-disable-next-line getter-return
// eslint-disable-next-line getter-return get length() {
get length() { unreachable("Should not access DecodeStream.length");
unreachable("Should not access DecodeStream.length");
},
get isEmpty() {
while (!this.eof && this.bufferLength === 0) {
this.readBlock();
}
return this.bufferLength === 0;
},
ensureBuffer: function DecodeStream_ensureBuffer(requested) {
const buffer = this.buffer;
if (requested <= buffer.byteLength) {
return buffer;
}
let size = this.minBufferLength;
while (size < requested) {
size *= 2;
}
const buffer2 = new Uint8Array(size);
buffer2.set(buffer);
return (this.buffer = buffer2);
},
getByte: function DecodeStream_getByte() {
const pos = this.pos;
while (this.bufferLength <= pos) {
if (this.eof) {
return -1;
}
this.readBlock();
}
return this.buffer[this.pos++];
},
getUint16: function DecodeStream_getUint16() {
const b0 = this.getByte();
const b1 = this.getByte();
if (b0 === -1 || b1 === -1) {
return -1;
}
return (b0 << 8) + b1;
},
getInt32: function DecodeStream_getInt32() {
const b0 = this.getByte();
const b1 = this.getByte();
const b2 = this.getByte();
const b3 = this.getByte();
return (b0 << 24) + (b1 << 16) + (b2 << 8) + b3;
},
getBytes(length, forceClamped = false) {
const pos = this.pos;
let end;
if (length) {
this.ensureBuffer(pos + length);
end = pos + length;
while (!this.eof && this.bufferLength < end) {
this.readBlock();
}
const bufEnd = this.bufferLength;
if (end > bufEnd) {
end = bufEnd;
}
} else {
while (!this.eof) {
this.readBlock();
}
end = this.bufferLength;
}
this.pos = end;
const subarray = this.buffer.subarray(pos, end);
// `this.buffer` is either a `Uint8Array` or `Uint8ClampedArray` here.
return forceClamped && !(subarray instanceof Uint8ClampedArray)
? new Uint8ClampedArray(subarray)
: subarray;
},
peekByte: function DecodeStream_peekByte() {
const peekedByte = this.getByte();
if (peekedByte !== -1) {
this.pos--;
}
return peekedByte;
},
peekBytes(length, forceClamped = false) {
const bytes = this.getBytes(length, forceClamped);
this.pos -= bytes.length;
return bytes;
},
makeSubStream: function DecodeStream_makeSubStream(start, length, dict) {
if (length === undefined) {
while (!this.eof) {
this.readBlock();
}
} else {
const end = start + length;
while (this.bufferLength <= end && !this.eof) {
this.readBlock();
}
}
return new Stream(this.buffer, start, length, dict);
},
getByteRange(begin, end) {
unreachable("Should not call DecodeStream.getByteRange");
},
skip: function DecodeStream_skip(n) {
if (!n) {
n = 1;
}
this.pos += n;
},
reset: function DecodeStream_reset() {
this.pos = 0;
},
getBaseStreams: function DecodeStream_getBaseStreams() {
if (this.str && this.str.getBaseStreams) {
return this.str.getBaseStreams();
}
return [];
},
};
return DecodeStream;
})();
const StreamsSequenceStream = (function StreamsSequenceStreamClosure() {
// eslint-disable-next-line no-shadow
function StreamsSequenceStream(streams) {
this.streams = streams;
let maybeLength = 0;
for (let i = 0, ii = streams.length; i < ii; i++) {
const stream = streams[i];
if (stream instanceof DecodeStream) {
maybeLength += stream._rawMinBufferLength;
} else {
maybeLength += stream.length;
}
}
DecodeStream.call(this, maybeLength);
} }
StreamsSequenceStream.prototype = Object.create(DecodeStream.prototype); get isEmpty() {
while (!this.eof && this.bufferLength === 0) {
this.readBlock();
}
return this.bufferLength === 0;
}
StreamsSequenceStream.prototype.readBlock = function streamSequenceStreamReadBlock() { ensureBuffer(requested) {
const buffer = this.buffer;
if (requested <= buffer.byteLength) {
return buffer;
}
let size = this.minBufferLength;
while (size < requested) {
size *= 2;
}
const buffer2 = new Uint8Array(size);
buffer2.set(buffer);
return (this.buffer = buffer2);
}
getByte() {
const pos = this.pos;
while (this.bufferLength <= pos) {
if (this.eof) {
return -1;
}
this.readBlock();
}
return this.buffer[this.pos++];
}
getUint16() {
const b0 = this.getByte();
const b1 = this.getByte();
if (b0 === -1 || b1 === -1) {
return -1;
}
return (b0 << 8) + b1;
}
getInt32() {
const b0 = this.getByte();
const b1 = this.getByte();
const b2 = this.getByte();
const b3 = this.getByte();
return (b0 << 24) + (b1 << 16) + (b2 << 8) + b3;
}
getBytes(length, forceClamped = false) {
const pos = this.pos;
let end;
if (length) {
this.ensureBuffer(pos + length);
end = pos + length;
while (!this.eof && this.bufferLength < end) {
this.readBlock();
}
const bufEnd = this.bufferLength;
if (end > bufEnd) {
end = bufEnd;
}
} else {
while (!this.eof) {
this.readBlock();
}
end = this.bufferLength;
}
this.pos = end;
const subarray = this.buffer.subarray(pos, end);
// `this.buffer` is either a `Uint8Array` or `Uint8ClampedArray` here.
return forceClamped && !(subarray instanceof Uint8ClampedArray)
? new Uint8ClampedArray(subarray)
: subarray;
}
peekByte() {
const peekedByte = this.getByte();
if (peekedByte !== -1) {
this.pos--;
}
return peekedByte;
}
peekBytes(length, forceClamped = false) {
const bytes = this.getBytes(length, forceClamped);
this.pos -= bytes.length;
return bytes;
}
makeSubStream(start, length, dict = null) {
if (length === undefined) {
while (!this.eof) {
this.readBlock();
}
} else {
const end = start + length;
while (this.bufferLength <= end && !this.eof) {
this.readBlock();
}
}
return new Stream(this.buffer, start, length, dict);
}
getByteRange(begin, end) {
unreachable("Should not call DecodeStream.getByteRange");
}
skip(n) {
if (!n) {
n = 1;
}
this.pos += n;
}
reset() {
this.pos = 0;
}
getBaseStreams() {
if (this.str && this.str.getBaseStreams) {
return this.str.getBaseStreams();
}
return [];
}
}
class StreamsSequenceStream extends DecodeStream {
constructor(streams) {
let maybeLength = 0;
for (const stream of streams) {
maybeLength +=
stream instanceof DecodeStream
? stream._rawMinBufferLength
: stream.length;
}
super(maybeLength);
this.streams = streams;
}
readBlock() {
const streams = this.streams; const streams = this.streams;
if (streams.length === 0) { if (streams.length === 0) {
this.eof = true; this.eof = true;
@ -202,20 +202,17 @@ const StreamsSequenceStream = (function StreamsSequenceStreamClosure() {
const buffer = this.ensureBuffer(newLength); const buffer = this.ensureBuffer(newLength);
buffer.set(chunk, bufferLength); buffer.set(chunk, bufferLength);
this.bufferLength = newLength; this.bufferLength = newLength;
}; }
StreamsSequenceStream.prototype.getBaseStreams = function StreamsSequenceStream_getBaseStreams() { getBaseStreams() {
const baseStreams = []; const baseStreams = [];
for (let i = 0, ii = this.streams.length; i < ii; i++) { for (const stream of this.streams) {
const stream = this.streams[i];
if (stream.getBaseStreams) { if (stream.getBaseStreams) {
baseStreams.push(...stream.getBaseStreams()); baseStreams.push(...stream.getBaseStreams());
} }
} }
return baseStreams; return baseStreams;
}; }
}
return StreamsSequenceStream;
})();
export { DecodeStream, StreamsSequenceStream }; export { DecodeStream, StreamsSequenceStream };