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diff --git a/intl/components/src/BidiEmbeddingLevel.h b/intl/components/src/BidiEmbeddingLevel.h
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+++ b/intl/components/src/BidiEmbeddingLevel.h
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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef intl_components_BidiEmbeddingLevel_h_
+#define intl_components_BidiEmbeddingLevel_h_
+
+#include <cstdint>
+
+/**
+ * This file has the BidiEmbeddingLevel and BidiDirection enum broken out from
+ * the main Bidi class for faster includes. This code is used in Layout which
+ * could trigger long build times when changing core mozilla::intl files.
+ */
+namespace mozilla::intl {
+
+/**
+ * This enum unambiguously classifies text runs as either being left to right,
+ * or right to left.
+ */
+enum class BidiDirection : uint8_t {
+  // Left to right text.
+  LTR = 0,
+  // Right to left text.
+  RTL = 1,
+};
+
+/**
+ * Embedding levels are numbers that indicate how deeply the bidi text is
+ * embedded, and the direction of text on that embedding level. When switching
+ * between strongly LTR code points and strongly RTL code points the embedding
+ * level normally switches between an embedding level of 0 (LTR) and 1 (RTL).
+ * The only time the embedding level increases is if the embedding code points
+ * are used. This is the Left-to-Right Embedding (LRE) code point (U+202A), or
+ * the Right-to-Left Embedding (RLE) code point (U+202B). The minimum
+ * embedding level of text is zero, and the maximum explicit depth is 125.
+ *
+ * The most significant bit is reserved for additional meaning. It can be used
+ * to signify in certain APIs that the text should by default be LTR or RTL if
+ * no strongly directional code points are found.
+ *
+ * Bug 1736595: At the time of this writing, some places in Gecko code use a 1
+ * in the most significant bit to indicate that an embedding level has not
+ * been set. This leads to an ambiguous understanding of what the most
+ * significant bit actually means.
+ */
+class BidiEmbeddingLevel {
+ public:
+  explicit BidiEmbeddingLevel(uint8_t aValue) : mValue(aValue) {}
+  explicit BidiEmbeddingLevel(int aValue)
+      : mValue(static_cast<uint8_t>(aValue)) {}
+
+  BidiEmbeddingLevel() = default;
+
+  // Enable the copy operators, but disable move as this is only a uint8_t.
+  BidiEmbeddingLevel(const BidiEmbeddingLevel& other) = default;
+  BidiEmbeddingLevel& operator=(const BidiEmbeddingLevel& other) = default;
+
+  /**
+   * Determine the direction of the embedding level by looking at the least
+   * significant bit. If it is 0, then it is LTR. If it is 1, then it is RTL.
+   */
+  BidiDirection Direction();
+
+  /**
+   * Create a left-to-right embedding level.
+   */
+  static BidiEmbeddingLevel LTR();
+
+  /**
+   * Create an right-to-left embedding level.
+   */
+  static BidiEmbeddingLevel RTL();
+
+  /**
+   * When passed into `SetParagraph`, the direction is determined by first
+   * strongly directional character, with the default set to left-to-right if
+   * none is found.
+   *
+   * This is encoded with the highest bit set to 1.
+   */
+  static BidiEmbeddingLevel DefaultLTR();
+
+  /**
+   * When passed into `SetParagraph`, the direction is determined by first
+   * strongly directional character, with the default set to right-to-left if
+   * none is found.
+   *
+   * * This is encoded with the highest and lowest bits set to 1.
+   */
+  static BidiEmbeddingLevel DefaultRTL();
+
+  bool IsDefaultLTR() const;
+  bool IsDefaultRTL() const;
+  bool IsLTR() const;
+  bool IsRTL() const;
+  bool IsSameDirection(BidiEmbeddingLevel aOther) const;
+
+  /**
+   * Get the underlying value as a uint8_t.
+   */
+  uint8_t Value() const;
+
+  /**
+   * Implicitly convert to the underlying value.
+   */
+  operator uint8_t() const { return mValue; }
+
+ private:
+  uint8_t mValue = 0;
+};
+
+}  // namespace mozilla::intl
+#endif