fork from https://github.com/mozilla/pdf.js.git

src/core/stream.js

@@ -0,0 +1,100 @@
+/* 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 { stringToBytes } from "../shared/util.js";
+
+class Stream extends BaseStream {
+  constructor(arrayBuffer, start, length, dict) {
+    super();
+
+    this.bytes =
+      arrayBuffer instanceof Uint8Array
+        ? arrayBuffer
+        : new Uint8Array(arrayBuffer);
+    this.start = start || 0;
+    this.pos = this.start;
+    this.end = start + length || this.bytes.length;
+    this.dict = dict;
+  }
+
+  get length() {
+    return this.end - this.start;
+  }
+
+  get isEmpty() {
+    return this.length === 0;
+  }
+
+  getByte() {
+    if (this.pos >= this.end) {
+      return -1;
+    }
+    return this.bytes[this.pos++];
+  }
+
+  getBytes(length) {
+    const pos = this.pos;
+    const endPos = !length ? this.end : Math.min(pos + length, this.end);
+
+    this.pos = endPos;
+    return this.bytes.subarray(pos, endPos);
+  }
+
+  getByteRange(begin, end) {
+    if (begin < 0) {
+      begin = 0;
+    }
+    if (end > this.end) {
+      end = this.end;
+    }
+    return this.bytes.subarray(begin, end);
+  }
+
+  reset() {
+    this.pos = this.start;
+  }
+
+  moveStart() {
+    this.start = this.pos;
+  }
+
+  makeSubStream(start, length, dict = null) {
+    return new Stream(this.bytes.buffer, start, length, dict);
+  }
+
+  clone() {
+    return new Stream(
+      this.bytes.buffer,
+      this.start,
+      this.length,
+      this.dict?.clone()
+    );
+  }
+}
+
+class StringStream extends Stream {
+  constructor(str, dict = null) {
+    super(stringToBytes(str), NaN, NaN, dict);
+  }
+}
+
+class NullStream extends Stream {
+  constructor() {
+    super(new Uint8Array(0));
+  }
+}
+
+export { NullStream, Stream, StringStream };