Add utility for looping from 0 to n.

TheModMaker · AnteWall · commit 662746809821 · 2019-07-17T16:17:57.000+02:00
Closes shaka-project#1518 Change-Id: I865f7a0311516d04ae84532dab873e1aaa31eb24
diff --git a/build/misspellings.txt b/build/misspellings.txt
@@ -5,6 +5,7 @@
     r'(?i)arti?fi?ci?ai?l': 'artificial',
     r'(?i)cur+ent': 'current',
     r'(?i)ful+screen': 'fullscreen',
+    r'(?i)interable': 'iterable',
     r'(?i)int(er|re)p(er|er)tation': 'interpretation',
     r'(?i)langauge': 'language',
     r'(?i)mananger': 'manager',
diff --git a/lib/dash/mpd_utils.js b/lib/dash/mpd_utils.js
@@ -233,7 +233,8 @@ shaka.dash.MpdUtils = class {
         timeline[timeline.length - 1].end = startTime / timescale;
       }
 
-      for (let j = 0; j <= repeat; ++j) {
+      for (const _ of shaka.util.Iterables.range(repeat + 1)) {
+        shaka.util.Functional.ignored(_);
         const endTime = startTime + d;
         const item = {
           start: startTime / timescale,
diff --git a/lib/dash/segment_list.js b/lib/dash/segment_list.js
@@ -25,6 +25,7 @@ goog.require('shaka.media.SegmentIndex');
 goog.require('shaka.media.SegmentReference');
 goog.require('shaka.util.Error');
 goog.require('shaka.util.Functional');
+goog.require('shaka.util.Iterables');
 goog.require('shaka.util.ManifestParserUtils');
 goog.require('shaka.util.XmlUtils');
 
@@ -212,7 +213,7 @@ shaka.dash.SegmentList = class {
     /** @type {!Array.<!shaka.media.SegmentReference>} */
     const references = [];
     let prevEndTime = info.startTime;
-    for (let i = 0; i < max; i++) {
+    for (const i of shaka.util.Iterables.range(max)) {
       const segment = info.mediaSegments[i];
       const mediaUri = ManifestParserUtils.resolveUris(
           baseUris, [segment.mediaUri]);
diff --git a/lib/media/adaptation_set.js b/lib/media/adaptation_set.js
@@ -18,6 +18,7 @@
 goog.provide('shaka.media.AdaptationSet');
 
 goog.require('goog.asserts');
+goog.require('shaka.util.Iterables');
 goog.require('shaka.util.MimeUtils');
 
 
@@ -219,7 +220,7 @@ shaka.media.AdaptationSet = class {
     codecsA.sort();
     codecsB.sort();
 
-    for (let i = 0; i < codecsA.length; i++) {
+    for (const i of shaka.util.Iterables.range(codecsA.length)) {
       if (codecsA[i] != codecsB[i]) {
         return false;
       }
diff --git a/lib/media/mp4_segment_index_parser.js b/lib/media/mp4_segment_index_parser.js
@@ -21,6 +21,7 @@ goog.require('goog.asserts');
 goog.require('shaka.log');
 goog.require('shaka.media.SegmentReference');
 goog.require('shaka.util.Error');
+goog.require('shaka.util.Iterables');
 goog.require('shaka.util.Mp4Parser');
 
 
@@ -123,7 +124,8 @@ shaka.media.Mp4SegmentIndexParser = class {
     let unscaledStartTime = earliestPresentationTime;
     let startByte = sidxOffset + box.size + firstOffset;
 
-    for (let i = 0; i < referenceCount; i++) {
+    for (const _ of shaka.util.Iterables.range(referenceCount)) {
+      shaka.util.Functional.ignored(_);
       // |chunk| is 1 bit for |referenceType|, and 31 bits for |referenceSize|.
       const chunk = box.reader.readUint32();
       const referenceType = (chunk & 0x80000000) >>> 31;
diff --git a/lib/media/streaming_engine.js b/lib/media/streaming_engine.js
@@ -2004,7 +2004,7 @@ shaka.media.StreamingEngine = class {
     }
 
     // Now setup all known Periods.
-    for (let i = 0; i < this.manifest_.periods.length; ++i) {
+    for (const i of shaka.util.Iterables.range(this.manifest_.periods.length)) {
       this.setupPeriod_(i).catch(Functional.noop);
     }
 
diff --git a/lib/media/time_ranges_utils.js b/lib/media/time_ranges_utils.js
@@ -17,6 +17,7 @@
 
 goog.provide('shaka.media.TimeRangesUtils');
 
+goog.require('shaka.util.Iterables');
 goog.require('shaka.util.Platform');
 
 
@@ -181,7 +182,7 @@ shaka.media.TimeRangesUtils = class {
       return [];
     }
     const ret = [];
-    for (let i = 0; i < b.length; i++) {
+    for (const i of shaka.util.Iterables.range(b.length)) {
       ret.push({start: b.start(i), end: b.end(i)});
     }
     return ret;
diff --git a/lib/text/mp4_vtt_parser.js b/lib/text/mp4_vtt_parser.js
@@ -25,6 +25,7 @@ goog.require('shaka.text.VttTextParser');
 goog.require('shaka.util.DataViewReader');
 goog.require('shaka.util.Error');
 goog.require('shaka.util.Functional');
+goog.require('shaka.util.Iterables');
 goog.require('shaka.util.Mp4Parser');
 goog.require('shaka.util.StringUtils');
 goog.require('shaka.util.TextParser');
@@ -299,7 +300,8 @@ shaka.text.Mp4VttParser = class {
 
     const samples = [];
 
-    for (let sampleIndex = 0; sampleIndex < sampleCount; sampleIndex++) {
+    for (const _ of shaka.util.Iterables.range(sampleCount)) {
+      shaka.util.Functional.ignored(_);
       /** @type {shaka.text.Mp4VttParser.TimeSegment} */
       const sample = {
         duration: null,
diff --git a/lib/util/ebml_parser.js b/lib/util/ebml_parser.js
@@ -144,11 +144,8 @@ shaka.util.EbmlParser = class {
     goog.asserts.assert(numBytes <= 8 && numBytes >= 1, 'Incorrect log2 value');
 
     const vint = new Uint8Array(numBytes);
-    vint[0] = firstByte;
-
-    // Include the remaining bytes.
-    for (let i = 1; i < numBytes; i++) {
-      vint[i] = this.reader_.readUint8();
+    for (const i of shaka.util.Iterables.range(numBytes)) {
+      vint[i] = i == 0 ? firstByte : this.reader_.readUint8();
     }
 
     return vint;
@@ -292,7 +289,7 @@ shaka.util.EbmlElement = class {
 
     let value = 0;
 
-    for (let i = 0; i < this.dataView_.byteLength; i++) {
+    for (const i of shaka.util.Iterables.range(this.dataView_.byteLength)) {
       const chunk = this.dataView_.getUint8(i);
       value = (256 * value) + chunk;
     }
diff --git a/lib/util/functional.js b/lib/util/functional.js
@@ -54,6 +54,13 @@ shaka.util.Functional = class {
     return all.concat(part);
   }
 
+  /**
+   * A no-op function that ignores its arguments.  This is used to suppress
+   * unused variable errors.
+   * @param {...*} args
+   */
+  static ignored(...args) {}
+
 
   /**
    * A no-op function.  Useful in promise chains.
diff --git a/lib/util/iterables.js b/lib/util/iterables.js
@@ -87,6 +87,18 @@ shaka.util.Iterables = class {
     return out;
   }
 
+  /**
+   * Returns an iterable that contains numbers in the range [0, end).
+   *
+   * @param {number=} end The exclusive end of the list.
+   * @return {!Iterable.<number>}
+   */
+  static* range(end) {
+    for (let i = 0; i < end; i++) {
+      yield i;
+    }
+  }
+
   /**
    * Iterates over an iterable object and includes additional info about each
    * item:
diff --git a/lib/util/mp4_parser.js b/lib/util/mp4_parser.js
@@ -20,6 +20,7 @@ goog.provide('shaka.util.Mp4Parser');
 goog.require('goog.asserts');
 goog.require('shaka.log');
 goog.require('shaka.util.DataViewReader');
+goog.require('shaka.util.Iterables');
 
 
 /**
@@ -208,10 +209,13 @@ shaka.util.Mp4Parser = class {
    * @export
    */
   static sampleDescription(box) {
-    for (let count = box.reader.readUint32();
-      count > 0 && !box.parser.done_;
-      count -= 1) {
+    const count = box.reader.readUint32();
+    for (const _ of shaka.util.Iterables.range(count)) {
+      shaka.util.Functional.ignored(_);
       box.parser.parseNext(box.start, box.reader, box.partialOkay);
+      if (box.parser.done_) {
+        break;
+      }
     }
   }
 
diff --git a/lib/util/pssh.js b/lib/util/pssh.js
@@ -19,6 +19,7 @@ goog.provide('shaka.util.Pssh');
 
 goog.require('goog.asserts');
 goog.require('shaka.log');
+goog.require('shaka.util.Iterables');
 goog.require('shaka.util.Mp4Parser');
 goog.require('shaka.util.Uint8ArrayUtils');
 
@@ -84,7 +85,8 @@ shaka.util.Pssh = class {
     const keyIds = [];
     if (box.version > 0) {
       const numKeyIds = box.reader.readUint32();
-      for (let i = 0; i < numKeyIds; ++i) {
+      for (const _ of shaka.util.Iterables.range(numKeyIds)) {
+        shaka.util.Functional.ignored(_);
         const keyId =
             shaka.util.Uint8ArrayUtils.toHex(box.reader.readBytes(16));
         keyIds.push(keyId);
diff --git a/lib/util/string_utils.js b/lib/util/string_utils.js
@@ -110,7 +110,7 @@ shaka.util.StringUtils = class {
     const length = Math.floor(data.byteLength / 2);
     const arr = new Uint16Array(length);
     const dataView = new DataView(buffer);
-    for (let i = 0; i < length; i++) {
+    for (const i of shaka.util.Iterables.range(length)) {
       arr[i] = dataView.getUint16(i * 2, littleEndian);
     }
     return shaka.util.StringUtils.fromCharCode(arr);
diff --git a/lib/util/uint8array_utils.js b/lib/util/uint8array_utils.js
@@ -81,9 +81,10 @@ shaka.util.Uint8ArrayUtils = class {
    * @export
    */
   static fromHex(str) {
-    const arr = new Uint8Array(str.length / 2);
-    for (let i = 0; i < str.length; i += 2) {
-      arr[i / 2] = window.parseInt(str.substr(i, 2), 16);
+    const size = str.length / 2;
+    const arr = new Uint8Array(size);
+    for (const i of shaka.util.Iterables.range(size)) {
+      arr[i] = window.parseInt(str.substr(i * 2, 2), 16);
     }
     return arr;
   }
@@ -128,7 +129,7 @@ shaka.util.Uint8ArrayUtils = class {
     if (arr1.length != arr2.length) {
       return false;
     }
-    for (let i = 0; i < arr1.length; ++i) {
+    for (const i of shaka.util.Iterables.range(arr1.length)) {
       if (arr1[i] != arr2[i]) {
         return false;
       }
diff --git a/test/cast/cast_receiver_integration.js b/test/cast/cast_receiver_integration.js
@@ -183,7 +183,8 @@ filterDescribe('CastReceiver', castReceiverIntegrationSupport, () => {
       // the average length is expected to be lower than the length of the first
       // update message.
       let totalLength = 0;
-      for (let i = 0; i < 50; i++) {
+      for (const _ of shaka.util.Iterables.range(50)) {
+        shaka.util.Functional.ignored(_);
         // eslint-disable-next-line no-await-in-loop
         const message = await waitForUpdateMessage();
         totalLength += message.length;
diff --git a/test/dash/dash_parser_content_protection_unit.js b/test/dash/dash_parser_content_protection_unit.js
@@ -104,7 +104,7 @@ describe('DashParser ContentProtection', () => {
     }
 
     const variants = [];
-    for (let i = 0; i < numVariants; i++) {
+    for (const i of shaka.util.Iterables.range(numVariants)) {
       const variant = jasmine.objectContaining({
         drmInfos: drmInfos,
         video: jasmine.objectContaining({
diff --git a/test/dash/mpd_utils_unit.js b/test/dash/mpd_utils_unit.js
@@ -522,10 +522,10 @@ describe('MpdUtils', () => {
 
     it('fails if it recurses too many times', async () => {
       const baseXMLString = inBaseContainer(
-          '<ToReplace xlink:href="https://xlink1" xlink:actuate="onLoad" />');
+          '<ToReplace xlink:href="https://xlink0" xlink:actuate="onLoad" />');
       // Create a large but finite number of links, so this won't
       // infinitely recurse if there isn't a depth limit.
-      for (let i = 1; i < 20; i++) {
+      for (const i of shaka.util.Iterables.range(20)) {
         const key = 'https://xlink' + i;
         const value = makeRecursiveXMLString(0, 'https://xlink' + (i + 1));
 
@@ -645,10 +645,10 @@ describe('MpdUtils', () => {
 
     it('interrupts requests on abort', async () => {
       const baseXMLString = inBaseContainer(
-          '<ToReplace xlink:href="https://xlink1" xlink:actuate="onLoad" />');
+          '<ToReplace xlink:href="https://xlink0" xlink:actuate="onLoad" />');
       // Create a few links.  This is few enough that it would succeed if we
       // didn't abort it.
-      for (let i = 1; i < 3; i++) {
+      for (const i of shaka.util.Iterables.range(4)) {
         const key = 'https://xlink' + i;
         const value = makeRecursiveXMLString(0, 'https://xlink' + (i + 1));
 
diff --git a/test/hls/hls_live_unit.js b/test/hls/hls_live_unit.js
@@ -406,7 +406,8 @@ describe('HlsParser live', () => {
       '#EXT-X-MAP:URI="init.mp4",BYTERANGE="616@0"\n',
       '#EXT-X-MEDIA-SEQUENCE:0\n',
     ].join('');
-    for (let i = 0; i < 1000; ++i) {
+    for (const _ of shaka.util.Iterables.range(1000)) {
+      shaka.util.Functional.ignored(_);
       mediaWithManySegments += '#EXTINF:2,\n';
       mediaWithManySegments += 'main.mp4\n';
     }
diff --git a/test/media/buffering_observer_unit.js b/test/media/buffering_observer_unit.js
@@ -123,7 +123,7 @@ describe('BufferingObserver', () => {
       /** @type {boolean} */
       let changed;
 
-      for (let lead = 0; lead <= 4; lead++) {
+      for (const lead of shaka.util.Iterables.range(5)) {
         changed = controller.update(lead, /* toEnd= */ false);
         expect(changed).toBeFalsy();
       }
diff --git a/test/media/period_observer_unit.js b/test/media/period_observer_unit.js
@@ -56,7 +56,7 @@ describe('PeriodObserver', () => {
     expect(onPeriodChanged).toHaveBeenCalledOnceMoreWith([manifest.periods[0]]);
 
     // Playing in period 0 (period 1 starts at 10).
-    for (let time = 1; time <= 9; time++) {
+    for (const time of shaka.util.Iterables.range(10)) {
       poll(observer, time);
       expect(onPeriodChanged).not.toHaveBeenCalled();
     }
diff --git a/test/media/streaming_engine_unit.js b/test/media/streaming_engine_unit.js
@@ -256,7 +256,7 @@ describe('StreamingEngine', () => {
     };
 
     const segmentsInFirstPeriod = 12;
-    for (let i = 0; i < segmentsInFirstPeriod; ++i) {
+    for (const i of shaka.util.Iterables.range(segmentsInFirstPeriod)) {
       segmentData[ContentType.AUDIO].segments.push(
           makeBuffer(segmentSizes[ContentType.AUDIO]));
       segmentData[ContentType.VIDEO].segments.push(
@@ -274,7 +274,7 @@ describe('StreamingEngine', () => {
     }
 
     const segmentsInSecondPeriod = 2;
-    for (let i = 0; i < segmentsInSecondPeriod; ++i) {
+    for (const i of shaka.util.Iterables.range(segmentsInSecondPeriod)) {
       segmentData[ContentType.AUDIO].segments.push(
           makeBuffer(segmentSizes[ContentType.AUDIO]));
       segmentData[ContentType.VIDEO].segments.push(
@@ -695,16 +695,10 @@ describe('StreamingEngine', () => {
 
     // Since we started playback from segment 11, segments 10 through 14
     // should be buffered.
-    for (let i = 0; i <= 8; ++i) {
-      expect(mediaSourceEngine.segments[ContentType.AUDIO][i]).toBeFalsy();
-      expect(mediaSourceEngine.segments[ContentType.VIDEO][i]).toBeFalsy();
-      expect(mediaSourceEngine.segments[ContentType.TEXT][i]).toBeFalsy();
-    }
-
-    for (let i = 9; i <= 13; ++i) {
-      expect(mediaSourceEngine.segments[ContentType.AUDIO][i]).toBeTruthy();
-      expect(mediaSourceEngine.segments[ContentType.VIDEO][i]).toBeTruthy();
-      expect(mediaSourceEngine.segments[ContentType.TEXT][i]).toBeTruthy();
+    for (const i of shaka.util.Iterables.range(14)) {
+      expect(mediaSourceEngine.segments[ContentType.AUDIO][i]).toBe(i >= 9);
+      expect(mediaSourceEngine.segments[ContentType.VIDEO][i]).toBe(i >= 9);
+      expect(mediaSourceEngine.segments[ContentType.TEXT][i]).toBe(i >= 9);
     }
   });
 
@@ -1824,16 +1818,10 @@ describe('StreamingEngine', () => {
 
       // Since we performed an unbuffered seek into the second Period, the
       // first 12 segments should not be buffered.
-      for (let i = 0; i <= 11; ++i) {
-        expect(mediaSourceEngine.segments[ContentType.AUDIO][i]).toBeFalsy();
-        expect(mediaSourceEngine.segments[ContentType.VIDEO][i]).toBeFalsy();
-        expect(mediaSourceEngine.segments[ContentType.TEXT][i]).toBeFalsy();
-      }
-
-      for (let i = 12; i <= 13; ++i) {
-        expect(mediaSourceEngine.segments[ContentType.AUDIO][i]).toBeTruthy();
-        expect(mediaSourceEngine.segments[ContentType.VIDEO][i]).toBeTruthy();
-        expect(mediaSourceEngine.segments[ContentType.TEXT][i]).toBeTruthy();
+      for (const i of shaka.util.Iterables.range(14)) {
+        expect(mediaSourceEngine.segments[ContentType.AUDIO][i]).toBe(i >= 12);
+        expect(mediaSourceEngine.segments[ContentType.VIDEO][i]).toBe(i >= 12);
+        expect(mediaSourceEngine.segments[ContentType.TEXT][i]).toBe(i >= 12);
       }
     });
   });
@@ -2627,16 +2615,10 @@ describe('StreamingEngine', () => {
         text: [],
       });
 
-      for (let i = 0; i <= 8; ++i) {
-        expect(mediaSourceEngine.segments['audio'][i]).toBeFalsy();
-        expect(mediaSourceEngine.segments['video'][i]).toBeFalsy();
-        expect(mediaSourceEngine.segments['text'][i]).toBeFalsy();
-      }
-
-      for (let i = 9; i <= 13; ++i) {
-        expect(mediaSourceEngine.segments['audio'][i]).toBeTruthy();
-        expect(mediaSourceEngine.segments['video'][i]).toBeTruthy();
-        expect(mediaSourceEngine.segments['text'][i]).toBeTruthy();
+      for (const i of shaka.util.Iterables.range(14)) {
+        expect(mediaSourceEngine.segments['audio'][i]).toBe(i >= 9);
+        expect(mediaSourceEngine.segments['video'][i]).toBe(i >= 9);
+        expect(mediaSourceEngine.segments['text'][i]).toBe(i >= 9);
       }
     }
 
diff --git a/test/test/util/indexeddb_utils.js b/test/test/util/indexeddb_utils.js
diff --git a/test/test/util/test_scheme.js b/test/test/util/test_scheme.js
diff --git a/test/test/util/util.js b/test/test/util/util.js
diff --git a/test/ui/ui_unit.js b/test/ui/ui_unit.js

Original file line number	Diff line number	Diff line change
`@@ -233,7 +233,8 @@ shaka.dash.MpdUtils = class {`
`233`	`233`	`timeline[timeline.length - 1].end = startTime / timescale;`
`234`	`234`	`}`
`235`	`235`
`236`		`- for (let j = 0; j <= repeat; ++j) {`
	`236`	`+ for (const _ of shaka.util.Iterables.range(repeat + 1)) {`
	`237`	`+ shaka.util.Functional.ignored(_);`
`237`	`238`	`const endTime = startTime + d;`
`238`	`239`	`const item = {`
`239`	`240`	`start: startTime / timescale,`
Original file line number	Diff line number	Diff line change
`@@ -2004,7 +2004,7 @@ shaka.media.StreamingEngine = class {`
`2004`	`2004`	`}`
`2005`	`2005`
`2006`	`2006`	`// Now setup all known Periods.`
`2007`		`- for (let i = 0; i < this.manifest_.periods.length; ++i) {`
	`2007`	`+ for (const i of shaka.util.Iterables.range(this.manifest_.periods.length)) {`
`2008`	`2008`	`this.setupPeriod_(i).catch(Functional.noop);`
`2009`	`2009`	`}`
`2010`	`2010`
Original file line number	Diff line number	Diff line change
`@@ -17,6 +17,7 @@`
`17`	`17`
`18`	`18`	`goog.provide('shaka.media.TimeRangesUtils');`
`19`	`19`
	`20`	`+goog.require('shaka.util.Iterables');`
`20`	`21`	`goog.require('shaka.util.Platform');`
`21`	`22`
`22`	`23`
`@@ -181,7 +182,7 @@ shaka.media.TimeRangesUtils = class {`
`181`	`182`	`return [];`
`182`	`183`	`}`
`183`	`184`	`const ret = [];`
`184`		`- for (let i = 0; i < b.length; i++) {`
	`185`	`+ for (const i of shaka.util.Iterables.range(b.length)) {`
`185`	`186`	`ret.push({start: b.start(i), end: b.end(i)});`
`186`	`187`	`}`
`187`	`188`	`return ret;`