Cleanup WebvttCueParser and WebvttCssStyle

- Remove scratchStyleMatches output parameter from WebvttCueParser.
- Switch from String[] to Set<String> for representing classes.
- In-line WebvttCssStyle.reset() since it's not used anywhere else.

PiperOrigin-RevId: 312249552

library/core/src/main/java/com/google/android/exoplayer2/text/webvtt/WebvttCssStyle.java

@@ -27,8 +27,8 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.util.Arrays;
 import java.util.Collections;
-import java.util.List;
-import org.checkerframework.checker.nullness.qual.EnsuresNonNull;
+import java.util.HashSet;
+import java.util.Set;
 
 /**
  * Style object of a Css style block in a Webvtt file.
@@ -80,7 +80,7 @@ public final class WebvttCssStyle {
   // Selector properties.
   private String targetId;
   private String targetTag;
-  private List<String> targetClasses;
+  private Set<String> targetClasses;
   private String targetVoice;
 
   // Style properties.
@@ -96,18 +96,10 @@ public final class WebvttCssStyle {
   @RubySpan.Position private int rubyPosition;
   private boolean combineUpright;
 
-  // Calling reset() is forbidden because `this` isn't initialized. This can be safely suppressed
-  // because reset() only assigns fields, it doesn't read any.
-  @SuppressWarnings("nullness:method.invocation.invalid")
   public WebvttCssStyle() {
-    reset();
-  }
-
-  @EnsuresNonNull({"targetId", "targetTag", "targetClasses", "targetVoice"})
-  public void reset() {
     targetId = "";
     targetTag = "";
-    targetClasses = Collections.emptyList();
+    targetClasses = Collections.emptySet();
     targetVoice = "";
     fontFamily = null;
     hasFontColor = false;
@@ -129,7 +121,7 @@ public final class WebvttCssStyle {
   }
 
   public void setTargetClasses(String[] targetClasses) {
-    this.targetClasses = Arrays.asList(targetClasses);
+    this.targetClasses = new HashSet<>(Arrays.asList(targetClasses));
   }
 
   public void setTargetVoice(String targetVoice) {
@@ -155,7 +147,7 @@ public final class WebvttCssStyle {
    * @return The score of the match, zero if there is no match.
    */
   public int getSpecificityScore(
-      @Nullable String id, @Nullable String tag, String[] classes, @Nullable String voice) {
+      @Nullable String id, @Nullable String tag, Set<String> classes, @Nullable String voice) {
     if (targetId.isEmpty() && targetTag.isEmpty() && targetClasses.isEmpty()
         && targetVoice.isEmpty()) {
       // The selector is universal. It matches with the minimum score if and only if the given
@@ -166,7 +158,7 @@ public final class WebvttCssStyle {
     score = updateScoreForMatch(score, targetId, id, 0x40000000);
     score = updateScoreForMatch(score, targetTag, tag, 2);
     score = updateScoreForMatch(score, targetVoice, voice, 4);
-    if (score == -1 || !Arrays.asList(classes).containsAll(targetClasses)) {
+    if (score == -1 || !classes.containsAll(targetClasses)) {
       return 0;
     } else {
       score += targetClasses.size() * 4;

library/core/src/main/java/com/google/android/exoplayer2/text/webvtt/WebvttCueParser.java

@@ -49,8 +49,10 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
@@ -239,7 +241,6 @@ public final class WebvttCueParser {
       @Nullable String id, String markup, List<WebvttCssStyle> styles) {
     SpannableStringBuilder spannedText = new SpannableStringBuilder();
     ArrayDeque<StartTag> startTagStack = new ArrayDeque<>();
-    List<StyleMatch> scratchStyleMatches = new ArrayList<>();
     int pos = 0;
     List<Element> nestedElements = new ArrayList<>();
     while (pos < markup.length()) {
@@ -270,8 +271,7 @@ public final class WebvttCueParser {
                 break;
               }
               startTag = startTagStack.pop();
-              applySpansForTag(
-                  id, startTag, nestedElements, spannedText, styles, scratchStyleMatches);
+              applySpansForTag(id, startTag, nestedElements, spannedText, styles);
               if (!startTagStack.isEmpty()) {
                 nestedElements.add(new Element(startTag, spannedText.length()));
               } else {
@@ -307,16 +307,14 @@ public final class WebvttCueParser {
     }
     // apply unclosed tags
     while (!startTagStack.isEmpty()) {
-      applySpansForTag(
-          id, startTagStack.pop(), nestedElements, spannedText, styles, scratchStyleMatches);
+      applySpansForTag(id, startTagStack.pop(), nestedElements, spannedText, styles);
     }
     applySpansForTag(
         id,
         StartTag.buildWholeCueVirtualTag(),
         /* nestedElements= */ Collections.emptyList(),
         spannedText,
-        styles,
-        scratchStyleMatches);
+        styles);
     return SpannedString.valueOf(spannedText);
   }
 
@@ -534,8 +532,7 @@ public final class WebvttCueParser {
       StartTag startTag,
       List<Element> nestedElements,
       SpannableStringBuilder text,
-      List<WebvttCssStyle> styles,
-      List<StyleMatch> scratchStyleMatches) {
+      List<WebvttCssStyle> styles) {
     int start = startTag.position;
     int end = text.length();
 
@@ -565,10 +562,9 @@ public final class WebvttCueParser {
         return;
     }
 
-    scratchStyleMatches.clear();
-    getApplicableStyles(styles, cueId, startTag, scratchStyleMatches);
-    for (int i = 0; i < scratchStyleMatches.size(); i++) {
-      applyStyleToText(text, scratchStyleMatches.get(i).style, start, end);
+    List<StyleMatch> applicableStyles = getApplicableStyles(styles, cueId, startTag);
+    for (int i = 0; i < applicableStyles.size(); i++) {
+      applyStyleToText(text, applicableStyles.get(i).style, start, end);
     }
   }
 
@@ -616,8 +612,7 @@ public final class WebvttCueParser {
   @RubySpan.Position
   private static int getRubyPosition(
       List<WebvttCssStyle> styles, @Nullable String cueId, StartTag startTag) {
-    List<StyleMatch> styleMatches = new ArrayList<>();
-    getApplicableStyles(styles, cueId, startTag, styleMatches);
+    List<StyleMatch> styleMatches = getApplicableStyles(styles, cueId, startTag);
     for (int i = 0; i < styleMatches.size(); i++) {
       WebvttCssStyle style = styleMatches.get(i).style;
       if (style.getRubyPosition() != RubySpan.POSITION_UNKNOWN) {
@@ -652,7 +647,7 @@ public final class WebvttCueParser {
    * colors</a>.
    */
   private static void applyDefaultColors(
-      SpannableStringBuilder text, String[] classes, int start, int end) {
+      SpannableStringBuilder text, Set<String> classes, int start, int end) {
     for (String className : classes) {
       if (DEFAULT_TEXT_COLORS.containsKey(className)) {
         int color = DEFAULT_TEXT_COLORS.get(className);
@@ -746,20 +741,18 @@ public final class WebvttCueParser {
     return Util.splitAtFirst(tagExpression, "[ \\.]")[0];
   }
 
-  private static void getApplicableStyles(
-      List<WebvttCssStyle> declaredStyles,
-      @Nullable String id,
-      StartTag tag,
-      List<StyleMatch> output) {
-    int styleCount = declaredStyles.size();
-    for (int i = 0; i < styleCount; i++) {
+  private static List<StyleMatch> getApplicableStyles(
+      List<WebvttCssStyle> declaredStyles, @Nullable String id, StartTag tag) {
+    List<StyleMatch> applicableStyles = new ArrayList<>();
+    for (int i = 0; i < declaredStyles.size(); i++) {
       WebvttCssStyle style = declaredStyles.get(i);
       int score = style.getSpecificityScore(id, tag.name, tag.classes, tag.voice);
       if (score > 0) {
-        output.add(new StyleMatch(score, style));
+        applicableStyles.add(new StyleMatch(score, style));
       }
     }
-    Collections.sort(output);
+    Collections.sort(applicableStyles);
+    return applicableStyles;
   }
 
   private static final class WebvttCueInfoBuilder {
@@ -929,14 +922,12 @@ public final class WebvttCueParser {
 
   private static final class StartTag {
 
-    private static final String[] NO_CLASSES = new String[0];
-
     public final String name;
     public final int position;
     public final String voice;
-    public final String[] classes;
+    public final Set<String> classes;
 
-    private StartTag(String name, int position, String voice, String[] classes) {
+    private StartTag(String name, int position, String voice, Set<String> classes) {
       this.position = position;
       this.name = name;
       this.voice = voice;
@@ -956,17 +947,19 @@ public final class WebvttCueParser {
       }
       String[] nameAndClasses = Util.split(fullTagExpression, "\\.");
       String name = nameAndClasses[0];
-      String[] classes;
-      if (nameAndClasses.length > 1) {
-        classes = Util.nullSafeArrayCopyOfRange(nameAndClasses, 1, nameAndClasses.length);
-      } else {
-        classes = NO_CLASSES;
+      Set<String> classes = new HashSet<>();
+      for (int i = 1; i < nameAndClasses.length; i++) {
+        classes.add(nameAndClasses[i]);
       }
       return new StartTag(name, position, voice, classes);
     }
 
     public static StartTag buildWholeCueVirtualTag() {
-      return new StartTag("", 0, "", new String[0]);
+      return new StartTag(
+          /* name= */ "",
+          /* position= */ 0,
+          /* voice= */ "",
+          /* classes= */ Collections.emptySet());
     }
 
   }

library/core/src/test/java/com/google/android/exoplayer2/text/webvtt/CssParserTest.java

@@ -21,6 +21,9 @@ import static com.google.common.truth.Truth.assertThat;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import com.google.android.exoplayer2.util.ParsableByteArray;
 import com.google.android.exoplayer2.util.Util;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashSet;
 import java.util.List;
 import org.junit.Before;
 import org.junit.Test;
@@ -163,32 +166,54 @@ public final class CssParserTest {
   public void styleScoreSystem() {
     WebvttCssStyle style = new WebvttCssStyle();
     // Universal selector.
-    assertThat(style.getSpecificityScore("", "", new String[0], "")).isEqualTo(1);
+    assertThat(style.getSpecificityScore("", "", Collections.emptySet(), "")).isEqualTo(1);
     // Class match without tag match.
     style.setTargetClasses(new String[] { "class1", "class2"});
-    assertThat(style.getSpecificityScore("", "", new String[]{"class1", "class2", "class3"},
-        "")).isEqualTo(8);
+    assertThat(
+            style.getSpecificityScore(
+                "", "", new HashSet<>(Arrays.asList("class1", "class2", "class3")), ""))
+        .isEqualTo(8);
     // Class and tag match
     style.setTargetTagName("b");
-    assertThat(style.getSpecificityScore("", "b",
-        new String[]{"class1", "class2", "class3"}, "")).isEqualTo(10);
+    assertThat(
+            style.getSpecificityScore(
+                "", "b", new HashSet<>(Arrays.asList("class1", "class2", "class3")), ""))
+        .isEqualTo(10);
     // Class insufficiency.
-    assertThat(style.getSpecificityScore("", "b", new String[]{"class1", "class"}, ""))
+    assertThat(
+            style.getSpecificityScore("", "b", new HashSet<>(Arrays.asList("class1", "class")), ""))
         .isEqualTo(0);
     // Voice, classes and tag match.
     style.setTargetVoice("Manuel Cráneo");
-    assertThat(style.getSpecificityScore("", "b",
-        new String[]{"class1", "class2", "class3"}, "Manuel Cráneo")).isEqualTo(14);
+    assertThat(
+            style.getSpecificityScore(
+                "",
+                "b",
+                new HashSet<>(Arrays.asList("class1", "class2", "class3")),
+                "Manuel Cráneo"))
+        .isEqualTo(14);
     // Voice mismatch.
-    assertThat(style.getSpecificityScore(null, "b",
-        new String[]{"class1", "class2", "class3"}, "Manuel Craneo")).isEqualTo(0);
+    assertThat(
+            style.getSpecificityScore(
+                null,
+                "b",
+                new HashSet<>(Arrays.asList("class1", "class2", "class3")),
+                "Manuel Craneo"))
+        .isEqualTo(0);
     // Id, voice, classes and tag match.
     style.setTargetId("id");
-    assertThat(style.getSpecificityScore("id", "b",
-        new String[]{"class1", "class2", "class3"}, "Manuel Cráneo")).isEqualTo(0x40000000 + 14);
+    assertThat(
+            style.getSpecificityScore(
+                "id",
+                "b",
+                new HashSet<>(Arrays.asList("class1", "class2", "class3")),
+                "Manuel Cráneo"))
+        .isEqualTo(0x40000000 + 14);
     // Id mismatch.
-    assertThat(style.getSpecificityScore("id1", "b",
-        new String[]{"class1", "class2", "class3"}, "")).isEqualTo(0);
+    assertThat(
+            style.getSpecificityScore(
+                "id1", "b", new HashSet<>(Arrays.asList("class1", "class2", "class3")), ""))
+        .isEqualTo(0);
   }
 
   // Utility methods.