Merge pull request #13303 from Snuffleupagus/BaseStream

Add an abstract base-class, which all the various Stream implementations inherit from

src/core/ascii_85_stream.js

@@ -0,0 +1,98 @@
+/* Copyright 2012 Mozilla Foundation
+ *
+ * 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.
+ */
+
+import { DecodeStream } from "./decode_stream.js";
+import { isWhiteSpace } from "./core_utils.js";
+
+class Ascii85Stream extends DecodeStream {
+  constructor(str, maybeLength) {
+    // Most streams increase in size when decoded, but Ascii85 streams
+    // typically shrink by ~20%.
+    if (maybeLength) {
+      maybeLength = 0.8 * maybeLength;
+    }
+    super(maybeLength);
+
+    this.str = str;
+    this.dict = str.dict;
+    this.input = new Uint8Array(5);
+  }
+
+  readBlock() {
+    const TILDA_CHAR = 0x7e; // '~'
+    const Z_LOWER_CHAR = 0x7a; // 'z'
+    const EOF = -1;
+
+    const str = this.str;
+
+    let c = str.getByte();
+    while (isWhiteSpace(c)) {
+      c = str.getByte();
+    }
+
+    if (c === EOF || c === TILDA_CHAR) {
+      this.eof = true;
+      return;
+    }
+
+    const bufferLength = this.bufferLength;
+    let buffer, i;
+
+    // special code for z
+    if (c === Z_LOWER_CHAR) {
+      buffer = this.ensureBuffer(bufferLength + 4);
+      for (i = 0; i < 4; ++i) {
+        buffer[bufferLength + i] = 0;
+      }
+      this.bufferLength += 4;
+    } else {
+      const input = this.input;
+      input[0] = c;
+      for (i = 1; i < 5; ++i) {
+        c = str.getByte();
+        while (isWhiteSpace(c)) {
+          c = str.getByte();
+        }
+
+        input[i] = c;
+
+        if (c === EOF || c === TILDA_CHAR) {
+          break;
+        }
+      }
+      buffer = this.ensureBuffer(bufferLength + i - 1);
+      this.bufferLength += i - 1;
+
+      // partial ending;
+      if (i < 5) {
+        for (; i < 5; ++i) {
+          input[i] = 0x21 + 84;
+        }
+        this.eof = true;
+      }
+      let t = 0;
+      for (i = 0; i < 5; ++i) {
+        t = t * 85 + (input[i] - 0x21);
+      }
+
+      for (i = 3; i >= 0; --i) {
+        buffer[bufferLength + i] = t & 0xff;
+        t >>= 8;
+      }
+    }
+  }
+}
+
+export { Ascii85Stream };

src/core/ascii_hex_stream.js

@@ -0,0 +1,79 @@
+/* Copyright 2012 Mozilla Foundation
+ *
+ * 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.
+ */
+
+import { DecodeStream } from "./decode_stream.js";
+
+class AsciiHexStream extends DecodeStream {
+  constructor(str, maybeLength) {
+    // Most streams increase in size when decoded, but AsciiHex streams shrink
+    // by 50%.
+    if (maybeLength) {
+      maybeLength = 0.5 * maybeLength;
+    }
+    super(maybeLength);
+
+    this.str = str;
+    this.dict = str.dict;
+
+    this.firstDigit = -1;
+  }
+
+  readBlock() {
+    const UPSTREAM_BLOCK_SIZE = 8000;
+    const bytes = this.str.getBytes(UPSTREAM_BLOCK_SIZE);
+    if (!bytes.length) {
+      this.eof = true;
+      return;
+    }
+
+    const maxDecodeLength = (bytes.length + 1) >> 1;
+    const buffer = this.ensureBuffer(this.bufferLength + maxDecodeLength);
+    let bufferLength = this.bufferLength;
+
+    let firstDigit = this.firstDigit;
+    for (const ch of bytes) {
+      let digit;
+      if (ch >= /* '0' = */ 0x30 && ch <= /* '9' = */ 0x39) {
+        digit = ch & 0x0f;
+      } else if (
+        (ch >= /* 'A' = */ 0x41 && ch <= /* 'Z' = */ 0x46) ||
+        (ch >= /* 'a' = */ 0x61 && ch <= /* 'z' = */ 0x66)
+      ) {
+        digit = (ch & 0x0f) + 9;
+      } else if (ch === /* '>' = */ 0x3e) {
+        this.eof = true;
+        break;
+      } else {
+        // Probably whitespace, ignoring.
+        continue;
+      }
+      if (firstDigit < 0) {
+        firstDigit = digit;
+      } else {
+        buffer[bufferLength++] = (firstDigit << 4) | digit;
+        firstDigit = -1;
+      }
+    }
+    if (firstDigit >= 0 && this.eof) {
+      // incomplete byte
+      buffer[bufferLength++] = firstDigit << 4;
+      firstDigit = -1;
+    }
+    this.firstDigit = firstDigit;
+    this.bufferLength = bufferLength;
+  }
+}
+
+export { AsciiHexStream };

src/core/base_stream.js

@@ -0,0 +1,106 @@
+/* Copyright 2021 Mozilla Foundation
+ *
+ * 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.
+ */
+
+import { shadow, unreachable } from "../shared/util.js";
+
+class BaseStream {
+  constructor() {
+    if (this.constructor === BaseStream) {
+      unreachable("Cannot initialize BaseStream.");
+    }
+  }
+
+  // eslint-disable-next-line getter-return
+  get length() {
+    unreachable("Abstract getter `length` accessed");
+  }
+
+  // eslint-disable-next-line getter-return
+  get isEmpty() {
+    unreachable("Abstract getter `isEmpty` accessed");
+  }
+
+  get isDataLoaded() {
+    return shadow(this, "isDataLoaded", true);
+  }
+
+  getByte() {
+    unreachable("Abstract method `getByte` called");
+  }
+
+  getBytes(length, forceClamped = false) {
+    unreachable("Abstract method `getBytes` called");
+  }
+
+  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;
+  }
+
+  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;
+  }
+
+  getByteRange(begin, end) {
+    unreachable("Abstract method `getByteRange` called");
+  }
+
+  skip(n) {
+    this.pos += n || 1;
+  }
+
+  reset() {
+    unreachable("Abstract method `reset` called");
+  }
+
+  moveStart() {
+    unreachable("Abstract method `moveStart` called");
+  }
+
+  makeSubStream(start, length, dict = null) {
+    unreachable("Abstract method `makeSubStream` called");
+  }
+
+  /**
+   * @returns {Array | null}
+   */
+  getBaseStreams() {
+    return null;
+  }
+}
+
+export { BaseStream };

src/core/ccitt_stream.js

@@ -15,7 +15,7 @@
 
 import { Dict, isDict } from "./primitives.js";
 import { CCITTFaxDecoder } from "./ccitt.js";
-import { DecodeStream } from "./stream.js";
+import { DecodeStream } from "./decode_stream.js";
 
 class CCITTFaxStream extends DecodeStream {
   constructor(str, maybeLength, params) {

src/core/chunked_stream.js

@@ -19,13 +19,17 @@ import {
   createPromiseCapability,
 } from "../shared/util.js";
 import { MissingDataException } from "./core_utils.js";
+import { Stream } from "./stream.js";
 
-class ChunkedStream {
+class ChunkedStream extends Stream {
   constructor(length, chunkSize, manager) {
-    this.bytes = new Uint8Array(length);
+    super(
-    this.start = 0;
+      /* arrayBuffer = */ new Uint8Array(length),
-    this.pos = 0;
+      /* start = */ 0,
-    this.end = length;
+      /* length = */ length,
+      /* dict = */ null
+    );
+
     this.chunkSize = chunkSize;
     this._loadedChunks = new Set();
     this.numChunks = Math.ceil(length / chunkSize);
@@ -46,15 +50,11 @@ class ChunkedStream {
     return chunks;
   }
 
-  getBaseStreams() {
-    return [this];
-  }
-
   get numChunksLoaded() {
     return this._loadedChunks.size;
   }
 
-  allChunksLoaded() {
+  get isDataLoaded() {
     return this.numChunksLoaded === this.numChunks;
   }
 
@@ -150,14 +150,6 @@ class ChunkedStream {
     return this._loadedChunks.has(chunk);
   }
 
-  get length() {
-    return this.end - this.start;
-  }
-
-  get isEmpty() {
-    return this.length === 0;
-  }
-
   getByte() {
     const pos = this.pos;
     if (pos >= this.end) {
@@ -169,24 +161,6 @@ class ChunkedStream {
     return this.bytes[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;
-  }
-
-  // Returns subarray of original buffer, should only be read.
   getBytes(length, forceClamped = false) {
     const bytes = this.bytes;
     const pos = this.pos;
@@ -215,20 +189,6 @@ class ChunkedStream {
     return forceClamped ? 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;
-  }
-
   getByteRange(begin, end) {
     if (begin < 0) {
       begin = 0;
@@ -242,22 +202,7 @@ class ChunkedStream {
     return this.bytes.subarray(begin, end);
   }
 
-  skip(n) {
+  makeSubStream(start, length, dict = null) {
-    if (!n) {
-      n = 1;
-    }
-    this.pos += n;
-  }
-
-  reset() {
-    this.pos = this.start;
-  }
-
-  moveStart() {
-    this.start = this.pos;
-  }
-
-  makeSubStream(start, length, dict) {
     if (length) {
       if (start + length > this.progressiveDataLength) {
         this.ensureRange(start, start + length);
@@ -291,12 +236,15 @@ class ChunkedStream {
       }
       return missingChunks;
     };
-    ChunkedStreamSubstream.prototype.allChunksLoaded = function () {
+    Object.defineProperty(ChunkedStreamSubstream.prototype, "isDataLoaded", {
+      get() {
         if (this.numChunksLoaded === this.numChunks) {
           return true;
         }
         return this.getMissingChunks().length === 0;
-    };
+      },
+      configurable: true,
+    });
 
     const subStream = new ChunkedStreamSubstream();
     subStream.pos = subStream.start = start;
@@ -304,6 +252,10 @@ class ChunkedStream {
     subStream.dict = dict;
     return subStream;
   }
+
+  getBaseStreams() {
+    return [this];
+  }
 }
 
 class ChunkedStreamManager {
@@ -521,7 +473,7 @@ class ChunkedStreamManager {
       this.stream.onReceiveData(begin, chunk);
     }
 
-    if (this.stream.allChunksLoaded()) {
+    if (this.stream.isDataLoaded) {
       this._loadedStreamCapability.resolve(this.stream);
     }
 

src/core/crypto.js

@@ -26,7 +26,7 @@ import {
   warn,
 } from "../shared/util.js";
 import { isDict, isName, Name } from "./primitives.js";
-import { DecryptStream } from "./stream.js";
+import { DecryptStream } from "./decrypt_stream.js";
 
 class ARCFourCipher {
   constructor(key) {

src/core/decode_stream.js

@@ -0,0 +1,170 @@
+/* Copyright 2012 Mozilla Foundation
+ *
+ * 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.
+ */
+
+import { BaseStream } from "./base_stream.js";
+import { Stream } from "./stream.js";
+
+// Lots of DecodeStreams are created whose buffers are never used.  For these
+// we share a single empty buffer. This is (a) space-efficient and (b) avoids
+// having special cases that would be required if we used |null| for an empty
+// buffer.
+const emptyBuffer = new Uint8Array(0);
+
+// Super class for the decoding streams.
+class DecodeStream extends BaseStream {
+  constructor(maybeMinBufferLength) {
+    super();
+    this._rawMinBufferLength = maybeMinBufferLength || 0;
+
+    this.pos = 0;
+    this.bufferLength = 0;
+    this.eof = false;
+    this.buffer = emptyBuffer;
+    this.minBufferLength = 512;
+    if (maybeMinBufferLength) {
+      // Compute the first power of two that is as big as maybeMinBufferLength.
+      while (this.minBufferLength < maybeMinBufferLength) {
+        this.minBufferLength *= 2;
+      }
+    }
+  }
+
+  get isEmpty() {
+    while (!this.eof && this.bufferLength === 0) {
+      this.readBlock();
+    }
+    return this.bufferLength === 0;
+  }
+
+  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++];
+  }
+
+  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;
+  }
+
+  reset() {
+    this.pos = 0;
+  }
+
+  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);
+  }
+
+  getBaseStreams() {
+    return this.str ? this.str.getBaseStreams() : null;
+  }
+}
+
+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;
+    if (streams.length === 0) {
+      this.eof = true;
+      return;
+    }
+    const stream = streams.shift();
+    const chunk = stream.getBytes();
+    const bufferLength = this.bufferLength;
+    const newLength = bufferLength + chunk.length;
+    const buffer = this.ensureBuffer(newLength);
+    buffer.set(chunk, bufferLength);
+    this.bufferLength = newLength;
+  }
+
+  getBaseStreams() {
+    const baseStreamsBuf = [];
+    for (const stream of this.streams) {
+      const baseStreams = stream.getBaseStreams();
+      if (baseStreams) {
+        baseStreamsBuf.push(...baseStreams);
+      }
+    }
+    return baseStreamsBuf.length > 0 ? baseStreamsBuf : null;
+  }
+}
+
+export { DecodeStream, StreamsSequenceStream };

src/core/decrypt_stream.js

@@ -0,0 +1,59 @@
+/* Copyright 2012 Mozilla Foundation
+ *
+ * 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.
+ */
+
+import { DecodeStream } from "./decode_stream.js";
+
+const chunkSize = 512;
+
+class DecryptStream extends DecodeStream {
+  constructor(str, maybeLength, decrypt) {
+    super(maybeLength);
+
+    this.str = str;
+    this.dict = str.dict;
+    this.decrypt = decrypt;
+    this.nextChunk = null;
+    this.initialized = false;
+  }
+
+  readBlock() {
+    let chunk;
+    if (this.initialized) {
+      chunk = this.nextChunk;
+    } else {
+      chunk = this.str.getBytes(chunkSize);
+      this.initialized = true;
+    }
+    if (!chunk || chunk.length === 0) {
+      this.eof = true;
+      return;
+    }
+    this.nextChunk = this.str.getBytes(chunkSize);
+    const hasMoreData = this.nextChunk && this.nextChunk.length > 0;
+
+    const decrypt = this.decrypt;
+    chunk = decrypt(chunk, !hasMoreData);
+
+    let bufferLength = this.bufferLength;
+    const n = chunk.length,
+      buffer = this.ensureBuffer(bufferLength + n);
+    for (let i = 0; i < n; i++) {
+      buffer[bufferLength++] = chunk[i];
+    }
+    this.bufferLength = bufferLength;
+  }
+}
+
+export { DecryptStream };

src/core/document.js

@@ -53,7 +53,7 @@ import {
   XRefEntryException,
   XRefParseException,
 } from "./core_utils.js";
-import { NullStream, Stream, StreamsSequenceStream } from "./stream.js";
+import { NullStream, Stream } from "./stream.js";
 import { AnnotationFactory } from "./annotation.js";
 import { calculateMD5 } from "./crypto.js";
 import { Catalog } from "./catalog.js";
@@ -61,6 +61,7 @@ import { Linearization } from "./parser.js";
 import { ObjectLoader } from "./object_loader.js";
 import { OperatorList } from "./operator_list.js";
 import { PartialEvaluator } from "./evaluator.js";
+import { StreamsSequenceStream } from "./decode_stream.js";
 import { StructTreePage } from "./struct_tree.js";
 import { XFAFactory } from "./xfa/factory.js";
 import { XRef } from "./xref.js";

src/core/evaluator.js

@@ -47,7 +47,6 @@ import {
   Ref,
   RefSet,
 } from "./primitives.js";
-import { DecodeStream, NullStream } from "./stream.js";
 import {
   ErrorFont,
   Font,
@@ -85,10 +84,12 @@ import {
 } from "./image_utils.js";
 import { bidi } from "./bidi.js";
 import { ColorSpace } from "./colorspace.js";
+import { DecodeStream } from "./decode_stream.js";
 import { getGlyphsUnicode } from "./glyphlist.js";
 import { getLookupTableFactory } from "./core_utils.js";
 import { getMetrics } from "./metrics.js";
 import { MurmurHash3_64 } from "./murmurhash3.js";
+import { NullStream } from "./stream.js";
 import { OperatorList } from "./operator_list.js";
 import { PDFImage } from "./image.js";
 

src/core/flate_stream.js

@@ -0,0 +1,401 @@
+/* Copyright 2012 Mozilla Foundation
+ *
+ * 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.
+ */
+/* Copyright 1996-2003 Glyph & Cog, LLC
+ *
+ * The flate stream implementation contained in this file is a JavaScript port
+ * of XPDF's implementation, made available under the Apache 2.0 open source
+ * license.
+ */
+
+import { DecodeStream } from "./decode_stream.js";
+import { FormatError } from "../shared/util.js";
+
+// prettier-ignore
+const codeLenCodeMap = new Int32Array([
+  16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15
+]);
+
+// prettier-ignore
+const lengthDecode = new Int32Array([
+  0x00003, 0x00004, 0x00005, 0x00006, 0x00007, 0x00008, 0x00009, 0x0000a,
+  0x1000b, 0x1000d, 0x1000f, 0x10011, 0x20013, 0x20017, 0x2001b, 0x2001f,
+  0x30023, 0x3002b, 0x30033, 0x3003b, 0x40043, 0x40053, 0x40063, 0x40073,
+  0x50083, 0x500a3, 0x500c3, 0x500e3, 0x00102, 0x00102, 0x00102
+]);
+
+// prettier-ignore
+const distDecode = new Int32Array([
+  0x00001, 0x00002, 0x00003, 0x00004, 0x10005, 0x10007, 0x20009, 0x2000d,
+  0x30011, 0x30019, 0x40021, 0x40031, 0x50041, 0x50061, 0x60081, 0x600c1,
+  0x70101, 0x70181, 0x80201, 0x80301, 0x90401, 0x90601, 0xa0801, 0xa0c01,
+  0xb1001, 0xb1801, 0xc2001, 0xc3001, 0xd4001, 0xd6001
+]);
+
+// prettier-ignore
+const fixedLitCodeTab = [new Int32Array([
+  0x70100, 0x80050, 0x80010, 0x80118, 0x70110, 0x80070, 0x80030, 0x900c0,
+  0x70108, 0x80060, 0x80020, 0x900a0, 0x80000, 0x80080, 0x80040, 0x900e0,
+  0x70104, 0x80058, 0x80018, 0x90090, 0x70114, 0x80078, 0x80038, 0x900d0,
+  0x7010c, 0x80068, 0x80028, 0x900b0, 0x80008, 0x80088, 0x80048, 0x900f0,
+  0x70102, 0x80054, 0x80014, 0x8011c, 0x70112, 0x80074, 0x80034, 0x900c8,
+  0x7010a, 0x80064, 0x80024, 0x900a8, 0x80004, 0x80084, 0x80044, 0x900e8,
+  0x70106, 0x8005c, 0x8001c, 0x90098, 0x70116, 0x8007c, 0x8003c, 0x900d8,
+  0x7010e, 0x8006c, 0x8002c, 0x900b8, 0x8000c, 0x8008c, 0x8004c, 0x900f8,
+  0x70101, 0x80052, 0x80012, 0x8011a, 0x70111, 0x80072, 0x80032, 0x900c4,
+  0x70109, 0x80062, 0x80022, 0x900a4, 0x80002, 0x80082, 0x80042, 0x900e4,
+  0x70105, 0x8005a, 0x8001a, 0x90094, 0x70115, 0x8007a, 0x8003a, 0x900d4,
+  0x7010d, 0x8006a, 0x8002a, 0x900b4, 0x8000a, 0x8008a, 0x8004a, 0x900f4,
+  0x70103, 0x80056, 0x80016, 0x8011e, 0x70113, 0x80076, 0x80036, 0x900cc,
+  0x7010b, 0x80066, 0x80026, 0x900ac, 0x80006, 0x80086, 0x80046, 0x900ec,
+  0x70107, 0x8005e, 0x8001e, 0x9009c, 0x70117, 0x8007e, 0x8003e, 0x900dc,
+  0x7010f, 0x8006e, 0x8002e, 0x900bc, 0x8000e, 0x8008e, 0x8004e, 0x900fc,
+  0x70100, 0x80051, 0x80011, 0x80119, 0x70110, 0x80071, 0x80031, 0x900c2,
+  0x70108, 0x80061, 0x80021, 0x900a2, 0x80001, 0x80081, 0x80041, 0x900e2,
+  0x70104, 0x80059, 0x80019, 0x90092, 0x70114, 0x80079, 0x80039, 0x900d2,
+  0x7010c, 0x80069, 0x80029, 0x900b2, 0x80009, 0x80089, 0x80049, 0x900f2,
+  0x70102, 0x80055, 0x80015, 0x8011d, 0x70112, 0x80075, 0x80035, 0x900ca,
+  0x7010a, 0x80065, 0x80025, 0x900aa, 0x80005, 0x80085, 0x80045, 0x900ea,
+  0x70106, 0x8005d, 0x8001d, 0x9009a, 0x70116, 0x8007d, 0x8003d, 0x900da,
+  0x7010e, 0x8006d, 0x8002d, 0x900ba, 0x8000d, 0x8008d, 0x8004d, 0x900fa,
+  0x70101, 0x80053, 0x80013, 0x8011b, 0x70111, 0x80073, 0x80033, 0x900c6,
+  0x70109, 0x80063, 0x80023, 0x900a6, 0x80003, 0x80083, 0x80043, 0x900e6,
+  0x70105, 0x8005b, 0x8001b, 0x90096, 0x70115, 0x8007b, 0x8003b, 0x900d6,
+  0x7010d, 0x8006b, 0x8002b, 0x900b6, 0x8000b, 0x8008b, 0x8004b, 0x900f6,
+  0x70103, 0x80057, 0x80017, 0x8011f, 0x70113, 0x80077, 0x80037, 0x900ce,
+  0x7010b, 0x80067, 0x80027, 0x900ae, 0x80007, 0x80087, 0x80047, 0x900ee,
+  0x70107, 0x8005f, 0x8001f, 0x9009e, 0x70117, 0x8007f, 0x8003f, 0x900de,
+  0x7010f, 0x8006f, 0x8002f, 0x900be, 0x8000f, 0x8008f, 0x8004f, 0x900fe,
+  0x70100, 0x80050, 0x80010, 0x80118, 0x70110, 0x80070, 0x80030, 0x900c1,
+  0x70108, 0x80060, 0x80020, 0x900a1, 0x80000, 0x80080, 0x80040, 0x900e1,
+  0x70104, 0x80058, 0x80018, 0x90091, 0x70114, 0x80078, 0x80038, 0x900d1,
+  0x7010c, 0x80068, 0x80028, 0x900b1, 0x80008, 0x80088, 0x80048, 0x900f1,
+  0x70102, 0x80054, 0x80014, 0x8011c, 0x70112, 0x80074, 0x80034, 0x900c9,
+  0x7010a, 0x80064, 0x80024, 0x900a9, 0x80004, 0x80084, 0x80044, 0x900e9,
+  0x70106, 0x8005c, 0x8001c, 0x90099, 0x70116, 0x8007c, 0x8003c, 0x900d9,
+  0x7010e, 0x8006c, 0x8002c, 0x900b9, 0x8000c, 0x8008c, 0x8004c, 0x900f9,
+  0x70101, 0x80052, 0x80012, 0x8011a, 0x70111, 0x80072, 0x80032, 0x900c5,
+  0x70109, 0x80062, 0x80022, 0x900a5, 0x80002, 0x80082, 0x80042, 0x900e5,
+  0x70105, 0x8005a, 0x8001a, 0x90095, 0x70115, 0x8007a, 0x8003a, 0x900d5,
+  0x7010d, 0x8006a, 0x8002a, 0x900b5, 0x8000a, 0x8008a, 0x8004a, 0x900f5,
+  0x70103, 0x80056, 0x80016, 0x8011e, 0x70113, 0x80076, 0x80036, 0x900cd,
+  0x7010b, 0x80066, 0x80026, 0x900ad, 0x80006, 0x80086, 0x80046, 0x900ed,
+  0x70107, 0x8005e, 0x8001e, 0x9009d, 0x70117, 0x8007e, 0x8003e, 0x900dd,
+  0x7010f, 0x8006e, 0x8002e, 0x900bd, 0x8000e, 0x8008e, 0x8004e, 0x900fd,
+  0x70100, 0x80051, 0x80011, 0x80119, 0x70110, 0x80071, 0x80031, 0x900c3,
+  0x70108, 0x80061, 0x80021, 0x900a3, 0x80001, 0x80081, 0x80041, 0x900e3,
+  0x70104, 0x80059, 0x80019, 0x90093, 0x70114, 0x80079, 0x80039, 0x900d3,
+  0x7010c, 0x80069, 0x80029, 0x900b3, 0x80009, 0x80089, 0x80049, 0x900f3,
+  0x70102, 0x80055, 0x80015, 0x8011d, 0x70112, 0x80075, 0x80035, 0x900cb,
+  0x7010a, 0x80065, 0x80025, 0x900ab, 0x80005, 0x80085, 0x80045, 0x900eb,
+  0x70106, 0x8005d, 0x8001d, 0x9009b, 0x70116, 0x8007d, 0x8003d, 0x900db,
+  0x7010e, 0x8006d, 0x8002d, 0x900bb, 0x8000d, 0x8008d, 0x8004d, 0x900fb,
+  0x70101, 0x80053, 0x80013, 0x8011b, 0x70111, 0x80073, 0x80033, 0x900c7,
+  0x70109, 0x80063, 0x80023, 0x900a7, 0x80003, 0x80083, 0x80043, 0x900e7,
+  0x70105, 0x8005b, 0x8001b, 0x90097, 0x70115, 0x8007b, 0x8003b, 0x900d7,
+  0x7010d, 0x8006b, 0x8002b, 0x900b7, 0x8000b, 0x8008b, 0x8004b, 0x900f7,
+  0x70103, 0x80057, 0x80017, 0x8011f, 0x70113, 0x80077, 0x80037, 0x900cf,
+  0x7010b, 0x80067, 0x80027, 0x900af, 0x80007, 0x80087, 0x80047, 0x900ef,
+  0x70107, 0x8005f, 0x8001f, 0x9009f, 0x70117, 0x8007f, 0x8003f, 0x900df,
+  0x7010f, 0x8006f, 0x8002f, 0x900bf, 0x8000f, 0x8008f, 0x8004f, 0x900ff
+]), 9];
+
+// prettier-ignore
+const fixedDistCodeTab = [new Int32Array([
+  0x50000, 0x50010, 0x50008, 0x50018, 0x50004, 0x50014, 0x5000c, 0x5001c,
+  0x50002, 0x50012, 0x5000a, 0x5001a, 0x50006, 0x50016, 0x5000e, 0x00000,
+  0x50001, 0x50011, 0x50009, 0x50019, 0x50005, 0x50015, 0x5000d, 0x5001d,
+  0x50003, 0x50013, 0x5000b, 0x5001b, 0x50007, 0x50017, 0x5000f, 0x00000
+]), 5];
+
+class FlateStream extends DecodeStream {
+  constructor(str, maybeLength) {
+    super(maybeLength);
+
+    this.str = str;
+    this.dict = str.dict;
+
+    const cmf = str.getByte();
+    const flg = str.getByte();
+    if (cmf === -1 || flg === -1) {
+      throw new FormatError(`Invalid header in flate stream: ${cmf}, ${flg}`);
+    }
+    if ((cmf & 0x0f) !== 0x08) {
+      throw new FormatError(
+        `Unknown compression method in flate stream: ${cmf}, ${flg}`
+      );
+    }
+    if (((cmf << 8) + flg) % 31 !== 0) {
+      throw new FormatError(`Bad FCHECK in flate stream: ${cmf}, ${flg}`);
+    }
+    if (flg & 0x20) {
+      throw new FormatError(`FDICT bit set in flate stream: ${cmf}, ${flg}`);
+    }
+
+    this.codeSize = 0;
+    this.codeBuf = 0;
+  }
+
+  getBits(bits) {
+    const str = this.str;
+    let codeSize = this.codeSize;
+    let codeBuf = this.codeBuf;
+
+    let b;
+    while (codeSize < bits) {
+      if ((b = str.getByte()) === -1) {
+        throw new FormatError("Bad encoding in flate stream");
+      }
+      codeBuf |= b << codeSize;
+      codeSize += 8;
+    }
+    b = codeBuf & ((1 << bits) - 1);
+    this.codeBuf = codeBuf >> bits;
+    this.codeSize = codeSize -= bits;
+
+    return b;
+  }
+
+  getCode(table) {
+    const str = this.str;
+    const codes = table[0];
+    const maxLen = table[1];
+    let codeSize = this.codeSize;
+    let codeBuf = this.codeBuf;
+
+    let b;
+    while (codeSize < maxLen) {
+      if ((b = str.getByte()) === -1) {
+        // premature end of stream. code might however still be valid.
+        // codeSize < codeLen check below guards against incomplete codeVal.
+        break;
+      }
+      codeBuf |= b << codeSize;
+      codeSize += 8;
+    }
+    const code = codes[codeBuf & ((1 << maxLen) - 1)];
+    const codeLen = code >> 16;
+    const codeVal = code & 0xffff;
+    if (codeLen < 1 || codeSize < codeLen) {
+      throw new FormatError("Bad encoding in flate stream");
+    }
+    this.codeBuf = codeBuf >> codeLen;
+    this.codeSize = codeSize - codeLen;
+    return codeVal;
+  }
+
+  generateHuffmanTable(lengths) {
+    const n = lengths.length;
+
+    // find max code length
+    let maxLen = 0;
+    let i;
+    for (i = 0; i < n; ++i) {
+      if (lengths[i] > maxLen) {
+        maxLen = lengths[i];
+      }
+    }
+
+    // build the table
+    const size = 1 << maxLen;
+    const codes = new Int32Array(size);
+    for (
+      let len = 1, code = 0, skip = 2;
+      len <= maxLen;
+      ++len, code <<= 1, skip <<= 1
+    ) {
+      for (let val = 0; val < n; ++val) {
+        if (lengths[val] === len) {
+          // bit-reverse the code
+          let code2 = 0;
+          let t = code;
+          for (i = 0; i < len; ++i) {
+            code2 = (code2 << 1) | (t & 1);
+            t >>= 1;
+          }
+
+          // fill the table entries
+          for (i = code2; i < size; i += skip) {
+            codes[i] = (len << 16) | val;
+          }
+          ++code;
+        }
+      }
+    }
+
+    return [codes, maxLen];
+  }
+
+  readBlock() {
+    let buffer, len;
+    const str = this.str;
+    // read block header
+    let hdr = this.getBits(3);
+    if (hdr & 1) {
+      this.eof = true;
+    }
+    hdr >>= 1;
+
+    if (hdr === 0) {
+      // uncompressed block
+      let b;
+
+      if ((b = str.getByte()) === -1) {
+        throw new FormatError("Bad block header in flate stream");
+      }
+      let blockLen = b;
+      if ((b = str.getByte()) === -1) {
+        throw new FormatError("Bad block header in flate stream");
+      }
+      blockLen |= b << 8;
+      if ((b = str.getByte()) === -1) {
+        throw new FormatError("Bad block header in flate stream");
+      }
+      let check = b;
+      if ((b = str.getByte()) === -1) {
+        throw new FormatError("Bad block header in flate stream");
+      }
+      check |= b << 8;
+      if (check !== (~blockLen & 0xffff) && (blockLen !== 0 || check !== 0)) {
+        // Ignoring error for bad "empty" block (see issue 1277)
+        throw new FormatError("Bad uncompressed block length in flate stream");
+      }
+
+      this.codeBuf = 0;
+      this.codeSize = 0;
+
+      const bufferLength = this.bufferLength,
+        end = bufferLength + blockLen;
+      buffer = this.ensureBuffer(end);
+      this.bufferLength = end;
+
+      if (blockLen === 0) {
+        if (str.peekByte() === -1) {
+          this.eof = true;
+        }
+      } else {
+        const block = str.getBytes(blockLen);
+        buffer.set(block, bufferLength);
+        if (block.length < blockLen) {
+          this.eof = true;
+        }
+      }
+      return;
+    }
+
+    let litCodeTable;
+    let distCodeTable;
+    if (hdr === 1) {
+      // compressed block, fixed codes
+      litCodeTable = fixedLitCodeTab;
+      distCodeTable = fixedDistCodeTab;
+    } else if (hdr === 2) {
+      // compressed block, dynamic codes
+      const numLitCodes = this.getBits(5) + 257;
+      const numDistCodes = this.getBits(5) + 1;
+      const numCodeLenCodes = this.getBits(4) + 4;
+
+      // build the code lengths code table
+      const codeLenCodeLengths = new Uint8Array(codeLenCodeMap.length);
+
+      let i;
+      for (i = 0; i < numCodeLenCodes; ++i) {
+        codeLenCodeLengths[codeLenCodeMap[i]] = this.getBits(3);
+      }
+      const codeLenCodeTab = this.generateHuffmanTable(codeLenCodeLengths);
+
+      // build the literal and distance code tables
+      len = 0;
+      i = 0;
+      const codes = numLitCodes + numDistCodes;
+      const codeLengths = new Uint8Array(codes);
+      let bitsLength, bitsOffset, what;
+      while (i < codes) {
+        const code = this.getCode(codeLenCodeTab);
+        if (code === 16) {
+          bitsLength = 2;
+          bitsOffset = 3;
+          what = len;
+        } else if (code === 17) {
+          bitsLength = 3;
+          bitsOffset = 3;
+          what = len = 0;
+        } else if (code === 18) {
+          bitsLength = 7;
+          bitsOffset = 11;
+          what = len = 0;
+        } else {
+          codeLengths[i++] = len = code;
+          continue;
+        }
+
+        let repeatLength = this.getBits(bitsLength) + bitsOffset;
+        while (repeatLength-- > 0) {
+          codeLengths[i++] = what;
+        }
+      }
+
+      litCodeTable = this.generateHuffmanTable(
+        codeLengths.subarray(0, numLitCodes)
+      );
+      distCodeTable = this.generateHuffmanTable(
+        codeLengths.subarray(numLitCodes, codes)
+      );
+    } else {
+      throw new FormatError("Unknown block type in flate stream");
+    }
+
+    buffer = this.buffer;
+    let limit = buffer ? buffer.length : 0;
+    let pos = this.bufferLength;
+    while (true) {
+      let code1 = this.getCode(litCodeTable);
+      if (code1 < 256) {
+        if (pos + 1 >= limit) {
+          buffer = this.ensureBuffer(pos + 1);
+          limit = buffer.length;
+        }
+        buffer[pos++] = code1;
+        continue;
+      }
+      if (code1 === 256) {
+        this.bufferLength = pos;
+        return;
+      }
+      code1 -= 257;
+      code1 = lengthDecode[code1];
+      let code2 = code1 >> 16;
+      if (code2 > 0) {
+        code2 = this.getBits(code2);
+      }
+      len = (code1 & 0xffff) + code2;
+      code1 = this.getCode(distCodeTable);
+      code1 = distDecode[code1];
+      code2 = code1 >> 16;
+      if (code2 > 0) {
+        code2 = this.getBits(code2);
+      }
+      const dist = (code1 & 0xffff) + code2;
+      if (pos + len >= limit) {
+        buffer = this.ensureBuffer(pos + len);
+        limit = buffer.length;
+      }
+      for (let k = 0; k < len; ++k, ++pos) {
+        buffer[pos] = buffer[pos - dist];
+      }
+    }
+  }
+}
+
+export { FlateStream };

src/core/image.js

@@ -16,7 +16,7 @@
 import { assert, FormatError, ImageKind, info, warn } from "../shared/util.js";
 import { isName, isStream, Name } from "./primitives.js";
 import { ColorSpace } from "./colorspace.js";
-import { DecodeStream } from "./stream.js";
+import { DecodeStream } from "./decode_stream.js";
 import { JpegStream } from "./jpeg_stream.js";
 import { JpxImage } from "./jpx.js";
 

src/core/jbig2_stream.js

@@ -14,7 +14,7 @@
  */
 
 import { isDict, isStream } from "./primitives.js";
-import { DecodeStream } from "./stream.js";
+import { DecodeStream } from "./decode_stream.js";
 import { Jbig2Image } from "./jbig2.js";
 import { shadow } from "../shared/util.js";
 
@@ -23,12 +23,12 @@ import { shadow } from "../shared/util.js";
  * the stream behaves like all the other DecodeStreams.
  */
 class Jbig2Stream extends DecodeStream {
-  constructor(stream, maybeLength, dict, params) {
+  constructor(stream, maybeLength, params) {
     super(maybeLength);
 
     this.stream = stream;
+    this.dict = stream.dict;
     this.maybeLength = maybeLength;
-    this.dict = dict;
     this.params = params;
   }
 

src/core/jpeg_stream.js

@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-import { DecodeStream } from "./stream.js";
+import { DecodeStream } from "./decode_stream.js";
 import { isDict } from "./primitives.js";
 import { JpegImage } from "./jpg.js";
 import { shadow } from "../shared/util.js";
@@ -23,7 +23,7 @@ import { shadow } from "../shared/util.js";
  * like all the other DecodeStreams.
  */
 class JpegStream extends DecodeStream {
-  constructor(stream, maybeLength, dict, params) {
+  constructor(stream, maybeLength, params) {
     // Some images may contain 'junk' before the SOI (start-of-image) marker.
     // Note: this seems to mainly affect inline images.
     let ch;
@@ -37,8 +37,8 @@ class JpegStream extends DecodeStream {
     super(maybeLength);
 
     this.stream = stream;
+    this.dict = stream.dict;
     this.maybeLength = maybeLength;
-    this.dict = dict;
     this.params = params;
   }
 

src/core/jpx_stream.js

@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-import { DecodeStream } from "./stream.js";
+import { DecodeStream } from "./decode_stream.js";
 import { JpxImage } from "./jpx.js";
 import { shadow } from "../shared/util.js";
 
@@ -22,12 +22,12 @@ import { shadow } from "../shared/util.js";
  * the stream behaves like all the other DecodeStreams.
  */
 class JpxStream extends DecodeStream {
-  constructor(stream, maybeLength, dict, params) {
+  constructor(stream, maybeLength, params) {
     super(maybeLength);
 
     this.stream = stream;
+    this.dict = stream.dict;
     this.maybeLength = maybeLength;
-    this.dict = dict;
     this.params = params;
   }
 

src/core/lzw_stream.js

@@ -0,0 +1,150 @@
+/* Copyright 2012 Mozilla Foundation
+ *
+ * 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.
+ */
+
+import { DecodeStream } from "./decode_stream.js";
+
+class LZWStream extends DecodeStream {
+  constructor(str, maybeLength, earlyChange) {
+    super(maybeLength);
+
+    this.str = str;
+    this.dict = str.dict;
+    this.cachedData = 0;
+    this.bitsCached = 0;
+
+    const maxLzwDictionarySize = 4096;
+    const lzwState = {
+      earlyChange,
+      codeLength: 9,
+      nextCode: 258,
+      dictionaryValues: new Uint8Array(maxLzwDictionarySize),
+      dictionaryLengths: new Uint16Array(maxLzwDictionarySize),
+      dictionaryPrevCodes: new Uint16Array(maxLzwDictionarySize),
+      currentSequence: new Uint8Array(maxLzwDictionarySize),
+      currentSequenceLength: 0,
+    };
+    for (let i = 0; i < 256; ++i) {
+      lzwState.dictionaryValues[i] = i;
+      lzwState.dictionaryLengths[i] = 1;
+    }
+    this.lzwState = lzwState;
+  }
+
+  readBits(n) {
+    let bitsCached = this.bitsCached;
+    let cachedData = this.cachedData;
+    while (bitsCached < n) {
+      const c = this.str.getByte();
+      if (c === -1) {
+        this.eof = true;
+        return null;
+      }
+      cachedData = (cachedData << 8) | c;
+      bitsCached += 8;
+    }
+    this.bitsCached = bitsCached -= n;
+    this.cachedData = cachedData;
+    this.lastCode = null;
+    return (cachedData >>> bitsCached) & ((1 << n) - 1);
+  }
+
+  readBlock() {
+    const blockSize = 512,
+      decodedSizeDelta = blockSize;
+    let estimatedDecodedSize = blockSize * 2;
+    let i, j, q;
+
+    const lzwState = this.lzwState;
+    if (!lzwState) {
+      return; // eof was found
+    }
+
+    const earlyChange = lzwState.earlyChange;
+    let nextCode = lzwState.nextCode;
+    const dictionaryValues = lzwState.dictionaryValues;
+    const dictionaryLengths = lzwState.dictionaryLengths;
+    const dictionaryPrevCodes = lzwState.dictionaryPrevCodes;
+    let codeLength = lzwState.codeLength;
+    let prevCode = lzwState.prevCode;
+    const currentSequence = lzwState.currentSequence;
+    let currentSequenceLength = lzwState.currentSequenceLength;
+
+    let decodedLength = 0;
+    let currentBufferLength = this.bufferLength;
+    let buffer = this.ensureBuffer(this.bufferLength + estimatedDecodedSize);
+
+    for (i = 0; i < blockSize; i++) {
+      const code = this.readBits(codeLength);
+      const hasPrev = currentSequenceLength > 0;
+      if (code < 256) {
+        currentSequence[0] = code;
+        currentSequenceLength = 1;
+      } else if (code >= 258) {
+        if (code < nextCode) {
+          currentSequenceLength = dictionaryLengths[code];
+          for (j = currentSequenceLength - 1, q = code; j >= 0; j--) {
+            currentSequence[j] = dictionaryValues[q];
+            q = dictionaryPrevCodes[q];
+          }
+        } else {
+          currentSequence[currentSequenceLength++] = currentSequence[0];
+        }
+      } else if (code === 256) {
+        codeLength = 9;
+        nextCode = 258;
+        currentSequenceLength = 0;
+        continue;
+      } else {
+        this.eof = true;
+        delete this.lzwState;
+        break;
+      }
+
+      if (hasPrev) {
+        dictionaryPrevCodes[nextCode] = prevCode;
+        dictionaryLengths[nextCode] = dictionaryLengths[prevCode] + 1;
+        dictionaryValues[nextCode] = currentSequence[0];
+        nextCode++;
+        codeLength =
+          (nextCode + earlyChange) & (nextCode + earlyChange - 1)
+            ? codeLength
+            : Math.min(
+                Math.log(nextCode + earlyChange) / 0.6931471805599453 + 1,
+                12
+              ) | 0;
+      }
+      prevCode = code;
+
+      decodedLength += currentSequenceLength;
+      if (estimatedDecodedSize < decodedLength) {
+        do {
+          estimatedDecodedSize += decodedSizeDelta;
+        } while (estimatedDecodedSize < decodedLength);
+        buffer = this.ensureBuffer(this.bufferLength + estimatedDecodedSize);
+      }
+      for (j = 0; j < currentSequenceLength; j++) {
+        buffer[currentBufferLength++] = currentSequence[j];
+      }
+    }
+    lzwState.nextCode = nextCode;
+    lzwState.codeLength = codeLength;
+    lzwState.prevCode = prevCode;
+    lzwState.currentSequenceLength = currentSequenceLength;
+
+    this.bufferLength = currentBufferLength;
+  }
+}
+
+export { LZWStream };

src/core/object_loader.js

@@ -61,12 +61,8 @@ class ObjectLoader {
   }
 
   async load() {
-    // Don't walk the graph if all the data is already loaded; note that only
+    // Don't walk the graph if all the data is already loaded.
-    // `ChunkedStream` instances have a `allChunksLoaded` method.
+    if (this.xref.stream.isDataLoaded) {
-    if (
-      !this.xref.stream.allChunksLoaded ||
-      this.xref.stream.allChunksLoaded()
-    ) {
       return undefined;
     }
 
@@ -112,20 +108,22 @@ class ObjectLoader {
           pendingRequests.push({ begin: ex.begin, end: ex.end });
         }
       }
-      if (currentNode && currentNode.getBaseStreams) {
+      if (isStream(currentNode)) {
         const baseStreams = currentNode.getBaseStreams();
+        if (baseStreams) {
           let foundMissingData = false;
-        for (let i = 0, ii = baseStreams.length; i < ii; i++) {
+          for (const stream of baseStreams) {
-          const stream = baseStreams[i];
+            if (stream.isDataLoaded) {
-          if (stream.allChunksLoaded && !stream.allChunksLoaded()) {
+              continue;
+            }
             foundMissingData = true;
             pendingRequests.push({ begin: stream.start, end: stream.end });
           }
-        }
           if (foundMissingData) {
             nodesToRevisit.push(currentNode);
           }
         }
+      }
 
       addChildren(currentNode, nodesToVisit);
     }
@@ -133,8 +131,7 @@ class ObjectLoader {
     if (pendingRequests.length) {
       await this.xref.stream.manager.requestRanges(pendingRequests);
 
-      for (let i = 0, ii = nodesToRevisit.length; i < ii; i++) {
+      for (const node of nodesToRevisit) {
-        const node = nodesToRevisit[i];
         // Remove any reference nodes from the current `RefSet` so they
         // aren't skipped when we revist them.
         if (node instanceof Ref) {

src/core/parser.js

@@ -13,15 +13,6 @@
  * limitations under the License.
  */
 
-import {
-  Ascii85Stream,
-  AsciiHexStream,
-  FlateStream,
-  LZWStream,
-  NullStream,
-  PredictorStream,
-  RunLengthStream,
-} from "./stream.js";
 import {
   assert,
   bytesToString,
@@ -43,10 +34,17 @@ import {
   Ref,
 } from "./primitives.js";
 import { isWhiteSpace, MissingDataException } from "./core_utils.js";
+import { Ascii85Stream } from "./ascii_85_stream.js";
+import { AsciiHexStream } from "./ascii_hex_stream.js";
 import { CCITTFaxStream } from "./ccitt_stream.js";
+import { FlateStream } from "./flate_stream.js";
 import { Jbig2Stream } from "./jbig2_stream.js";
 import { JpegStream } from "./jpeg_stream.js";
 import { JpxStream } from "./jpx_stream.js";
+import { LZWStream } from "./lzw_stream.js";
+import { NullStream } from "./stream.js";
+import { PredictorStream } from "./predictor_stream.js";
+import { RunLengthStream } from "./run_length_stream.js";
 
 const MAX_LENGTH_TO_CACHE = 1000;
 const MAX_ADLER32_LENGTH = 5552;
@@ -767,11 +765,11 @@ class Parser {
       }
       if (name === "DCTDecode" || name === "DCT") {
         xrefStreamStats[StreamType.DCT] = true;
-        return new JpegStream(stream, maybeLength, stream.dict, params);
+        return new JpegStream(stream, maybeLength, params);
       }
       if (name === "JPXDecode" || name === "JPX") {
         xrefStreamStats[StreamType.JPX] = true;
-        return new JpxStream(stream, maybeLength, stream.dict, params);
+        return new JpxStream(stream, maybeLength, params);
       }
       if (name === "ASCII85Decode" || name === "A85") {
         xrefStreamStats[StreamType.A85] = true;
@@ -791,7 +789,7 @@ class Parser {
       }
       if (name === "JBIG2Decode") {
         xrefStreamStats[StreamType.JBIG] = true;
-        return new Jbig2Stream(stream, maybeLength, stream.dict, params);
+        return new Jbig2Stream(stream, maybeLength, params);
       }
       warn(`Filter "${name}" is not supported.`);
       return stream;

src/core/predictor_stream.js

@@ -0,0 +1,238 @@
+/* Copyright 2012 Mozilla Foundation
+ *
+ * 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.
+ */
+
+import { DecodeStream } from "./decode_stream.js";
+import { FormatError } from "../shared/util.js";
+import { isDict } from "./primitives.js";
+
+class PredictorStream extends DecodeStream {
+  constructor(str, maybeLength, params) {
+    if (!isDict(params)) {
+      return str; // no prediction
+    }
+    const predictor = params.get("Predictor") || 1;
+
+    if (predictor <= 1) {
+      return str; // no prediction
+    }
+    if (predictor !== 2 && (predictor < 10 || predictor > 15)) {
+      throw new FormatError(`Unsupported predictor: ${predictor}`);
+    }
+    super(maybeLength);
+    this.predictor = predictor;
+
+    if (predictor === 2) {
+      this.readBlock = this.readBlockTiff;
+    } else {
+      this.readBlock = this.readBlockPng;
+    }
+
+    this.str = str;
+    this.dict = str.dict;
+
+    const colors = (this.colors = params.get("Colors") || 1);
+    const bits = (this.bits = params.get("BitsPerComponent") || 8);
+    const columns = (this.columns = params.get("Columns") || 1);
+
+    this.pixBytes = (colors * bits + 7) >> 3;
+    this.rowBytes = (columns * colors * bits + 7) >> 3;
+
+    return this;
+  }
+
+  readBlockTiff() {
+    const rowBytes = this.rowBytes;
+
+    const bufferLength = this.bufferLength;
+    const buffer = this.ensureBuffer(bufferLength + rowBytes);
+
+    const bits = this.bits;
+    const colors = this.colors;
+
+    const rawBytes = this.str.getBytes(rowBytes);
+    this.eof = !rawBytes.length;
+    if (this.eof) {
+      return;
+    }
+
+    let inbuf = 0,
+      outbuf = 0;
+    let inbits = 0,
+      outbits = 0;
+    let pos = bufferLength;
+    let i;
+
+    if (bits === 1 && colors === 1) {
+      // Optimized version of the loop in the "else"-branch
+      // for 1 bit-per-component and 1 color TIFF images.
+      for (i = 0; i < rowBytes; ++i) {
+        let c = rawBytes[i] ^ inbuf;
+        c ^= c >> 1;
+        c ^= c >> 2;
+        c ^= c >> 4;
+        inbuf = (c & 1) << 7;
+        buffer[pos++] = c;
+      }
+    } else if (bits === 8) {
+      for (i = 0; i < colors; ++i) {
+        buffer[pos++] = rawBytes[i];
+      }
+      for (; i < rowBytes; ++i) {
+        buffer[pos] = buffer[pos - colors] + rawBytes[i];
+        pos++;
+      }
+    } else if (bits === 16) {
+      const bytesPerPixel = colors * 2;
+      for (i = 0; i < bytesPerPixel; ++i) {
+        buffer[pos++] = rawBytes[i];
+      }
+      for (; i < rowBytes; i += 2) {
+        const sum =
+          ((rawBytes[i] & 0xff) << 8) +
+          (rawBytes[i + 1] & 0xff) +
+          ((buffer[pos - bytesPerPixel] & 0xff) << 8) +
+          (buffer[pos - bytesPerPixel + 1] & 0xff);
+        buffer[pos++] = (sum >> 8) & 0xff;
+        buffer[pos++] = sum & 0xff;
+      }
+    } else {
+      const compArray = new Uint8Array(colors + 1);
+      const bitMask = (1 << bits) - 1;
+      let j = 0,
+        k = bufferLength;
+      const columns = this.columns;
+      for (i = 0; i < columns; ++i) {
+        for (let kk = 0; kk < colors; ++kk) {
+          if (inbits < bits) {
+            inbuf = (inbuf << 8) | (rawBytes[j++] & 0xff);
+            inbits += 8;
+          }
+          compArray[kk] =
+            (compArray[kk] + (inbuf >> (inbits - bits))) & bitMask;
+          inbits -= bits;
+          outbuf = (outbuf << bits) | compArray[kk];
+          outbits += bits;
+          if (outbits >= 8) {
+            buffer[k++] = (outbuf >> (outbits - 8)) & 0xff;
+            outbits -= 8;
+          }
+        }
+      }
+      if (outbits > 0) {
+        buffer[k++] =
+          (outbuf << (8 - outbits)) + (inbuf & ((1 << (8 - outbits)) - 1));
+      }
+    }
+    this.bufferLength += rowBytes;
+  }
+
+  readBlockPng() {
+    const rowBytes = this.rowBytes;
+    const pixBytes = this.pixBytes;
+
+    const predictor = this.str.getByte();
+    const rawBytes = this.str.getBytes(rowBytes);
+    this.eof = !rawBytes.length;
+    if (this.eof) {
+      return;
+    }
+
+    const bufferLength = this.bufferLength;
+    const buffer = this.ensureBuffer(bufferLength + rowBytes);
+
+    let prevRow = buffer.subarray(bufferLength - rowBytes, bufferLength);
+    if (prevRow.length === 0) {
+      prevRow = new Uint8Array(rowBytes);
+    }
+
+    let i,
+      j = bufferLength,
+      up,
+      c;
+    switch (predictor) {
+      case 0:
+        for (i = 0; i < rowBytes; ++i) {
+          buffer[j++] = rawBytes[i];
+        }
+        break;
+      case 1:
+        for (i = 0; i < pixBytes; ++i) {
+          buffer[j++] = rawBytes[i];
+        }
+        for (; i < rowBytes; ++i) {
+          buffer[j] = (buffer[j - pixBytes] + rawBytes[i]) & 0xff;
+          j++;
+        }
+        break;
+      case 2:
+        for (i = 0; i < rowBytes; ++i) {
+          buffer[j++] = (prevRow[i] + rawBytes[i]) & 0xff;
+        }
+        break;
+      case 3:
+        for (i = 0; i < pixBytes; ++i) {
+          buffer[j++] = (prevRow[i] >> 1) + rawBytes[i];
+        }
+        for (; i < rowBytes; ++i) {
+          buffer[j] =
+            (((prevRow[i] + buffer[j - pixBytes]) >> 1) + rawBytes[i]) & 0xff;
+          j++;
+        }
+        break;
+      case 4:
+        // we need to save the up left pixels values. the simplest way
+        // is to create a new buffer
+        for (i = 0; i < pixBytes; ++i) {
+          up = prevRow[i];
+          c = rawBytes[i];
+          buffer[j++] = up + c;
+        }
+        for (; i < rowBytes; ++i) {
+          up = prevRow[i];
+          const upLeft = prevRow[i - pixBytes];
+          const left = buffer[j - pixBytes];
+          const p = left + up - upLeft;
+
+          let pa = p - left;
+          if (pa < 0) {
+            pa = -pa;
+          }
+          let pb = p - up;
+          if (pb < 0) {
+            pb = -pb;
+          }
+          let pc = p - upLeft;
+          if (pc < 0) {
+            pc = -pc;
+          }
+
+          c = rawBytes[i];
+          if (pa <= pb && pa <= pc) {
+            buffer[j++] = left + c;
+          } else if (pb <= pc) {
+            buffer[j++] = up + c;
+          } else {
+            buffer[j++] = upLeft + c;
+          }
+        }
+        break;
+      default:
+        throw new FormatError(`Unsupported predictor: ${predictor}`);
+    }
+    this.bufferLength += rowBytes;
+  }
+}
+
+export { PredictorStream };

src/core/primitives.js

@@ -14,6 +14,7 @@
  */
 
 import { assert, unreachable } from "../shared/util.js";
+import { BaseStream } from "./base_stream.js";
 
 const EOF = {};
 
@@ -383,7 +384,7 @@ function isRefsEqual(v1, v2) {
 }
 
 function isStream(v) {
-  return typeof v === "object" && v !== null && v.getBytes !== undefined;
+  return v instanceof BaseStream;
 }
 
 function clearPrimitiveCaches() {

src/core/run_length_stream.js

@@ -0,0 +1,61 @@
+/* Copyright 2012 Mozilla Foundation
+ *
+ * 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.
+ */
+
+import { DecodeStream } from "./decode_stream.js";
+
+class RunLengthStream extends DecodeStream {
+  constructor(str, maybeLength) {
+    super(maybeLength);
+
+    this.str = str;
+    this.dict = str.dict;
+  }
+
+  readBlock() {
+    // The repeatHeader has following format. The first byte defines type of run
+    // and amount of bytes to repeat/copy: n = 0 through 127 - copy next n bytes
+    // (in addition to the second byte from the header), n = 129 through 255 -
+    // duplicate the second byte from the header (257 - n) times, n = 128 - end.
+    const repeatHeader = this.str.getBytes(2);
+    if (!repeatHeader || repeatHeader.length < 2 || repeatHeader[0] === 128) {
+      this.eof = true;
+      return;
+    }
+
+    let buffer;
+    let bufferLength = this.bufferLength;
+    let n = repeatHeader[0];
+    if (n < 128) {
+      // copy n bytes
+      buffer = this.ensureBuffer(bufferLength + n + 1);
+      buffer[bufferLength++] = repeatHeader[1];
+      if (n > 0) {
+        const source = this.str.getBytes(n);
+        buffer.set(source, bufferLength);
+        bufferLength += n;
+      }
+    } else {
+      n = 257 - n;
+      const b = repeatHeader[1];
+      buffer = this.ensureBuffer(bufferLength + n + 1);
+      for (let i = 0; i < n; i++) {
+        buffer[bufferLength++] = b;
+      }
+    }
+    this.bufferLength = bufferLength;
+  }
+}
+
+export { RunLengthStream };

test/unit/stream_spec.js

@@ -13,8 +13,9 @@
  * limitations under the License.
  */
 
-import { PredictorStream, Stream } from "../../src/core/stream.js";
 import { Dict } from "../../src/core/primitives.js";
+import { PredictorStream } from "../../src/core/predictor_stream.js";
+import { Stream } from "../../src/core/stream.js";
 
 describe("stream", function () {
   beforeEach(function () {