1 files changed, 119 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/text/webvtt/WebvttParserUtil.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/text/webvtt/WebvttParserUtil.java
new file mode 100644
index 0000000000..b87d014de0
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/text/webvtt/WebvttParserUtil.java
@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * 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.
+ */
+package org.mozilla.thirdparty.com.google.android.exoplayer2.text.webvtt;
+
+import androidx.annotation.Nullable;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.ParserException;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.ParsableByteArray;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Util;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * Utility methods for parsing WebVTT data.
+ */
+public final class WebvttParserUtil {
+
+  private static final Pattern COMMENT = Pattern.compile("^NOTE([ \t].*)?$");
+  private static final String WEBVTT_HEADER = "WEBVTT";
+
+  private WebvttParserUtil() {}
+
+  /**
+   * Reads and validates the first line of a WebVTT file.
+   *
+   * @param input The input from which the line should be read.
+   * @throws ParserException If the line isn't the start of a valid WebVTT file.
+   */
+  public static void validateWebvttHeaderLine(ParsableByteArray input) throws ParserException {
+    int startPosition = input.getPosition();
+    if (!isWebvttHeaderLine(input)) {
+      input.setPosition(startPosition);
+      throw new ParserException("Expected WEBVTT. Got " + input.readLine());
+    }
+  }
+
+  /**
+   * Returns whether the given input is the first line of a WebVTT file.
+   *
+   * @param input The input from which the line should be read.
+   */
+  public static boolean isWebvttHeaderLine(ParsableByteArray input) {
+    @Nullable String line = input.readLine();
+    return line != null && line.startsWith(WEBVTT_HEADER);
+  }
+
+  /**
+   * Parses a WebVTT timestamp.
+   *
+   * @param timestamp The timestamp string.
+   * @return The parsed timestamp in microseconds.
+   * @throws NumberFormatException If the timestamp could not be parsed.
+   */
+  public static long parseTimestampUs(String timestamp) throws NumberFormatException {
+    long value = 0;
+    String[] parts = Util.splitAtFirst(timestamp, "\\.");
+    String[] subparts = Util.split(parts[0], ":");
+    for (String subpart : subparts) {
+      value = (value * 60) + Long.parseLong(subpart);
+    }
+    value *= 1000;
+    if (parts.length == 2) {
+      value += Long.parseLong(parts[1]);
+    }
+    return value * 1000;
+  }
+
+  /**
+   * Parses a percentage string.
+   *
+   * @param s The percentage string.
+   * @return The parsed value, where 1.0 represents 100%.
+   * @throws NumberFormatException If the percentage could not be parsed.
+   */
+  public static float parsePercentage(String s) throws NumberFormatException {
+    if (!s.endsWith("%")) {
+      throw new NumberFormatException("Percentages must end with %");
+    }
+    return Float.parseFloat(s.substring(0, s.length() - 1)) / 100;
+  }
+
+  /**
+   * Reads lines up to and including the next WebVTT cue header.
+   *
+   * @param input The input from which lines should be read.
+   * @return A {@link Matcher} for the WebVTT cue header, or null if the end of the input was
+   *     reached without a cue header being found. In the case that a cue header is found, groups 1,
+   *     2 and 3 of the returned matcher contain the start time, end time and settings list.
+   */
+  @Nullable
+  public static Matcher findNextCueHeader(ParsableByteArray input) {
+    @Nullable String line;
+    while ((line = input.readLine()) != null) {
+      if (COMMENT.matcher(line).matches()) {
+        // Skip until the end of the comment block.
+        while ((line = input.readLine()) != null && !line.isEmpty()) {}
+      } else {
+        Matcher cueHeaderMatcher = WebvttCueParser.CUE_HEADER_PATTERN.matcher(line);
+        if (cueHeaderMatcher.matches()) {
+          return cueHeaderMatcher;
+        }
+      }
+    }
+    return null;
+  }
+
+}