1 files changed, 73 insertions, 0 deletions
diff --git a/toolkit/components/glean/bindings/private/String.h b/toolkit/components/glean/bindings/private/String.h
new file mode 100644
index 0000000000..8c3c6ae05e
--- /dev/null
+++ b/toolkit/components/glean/bindings/private/String.h
@@ -0,0 +1,73 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 mozilla_glean_GleanString_h
+#define mozilla_glean_GleanString_h
+
+#include "mozilla/Maybe.h"
+#include "mozilla/Result.h"
+#include "nsIGleanMetrics.h"
+#include "nsString.h"
+
+namespace mozilla::glean {
+
+namespace impl {
+
+class StringMetric {
+ public:
+  constexpr explicit StringMetric(uint32_t aId) : mId(aId) {}
+
+  /*
+   * Set to the specified value.
+   *
+   * Truncates the value if it is longer than 100 bytes and logs an error.
+   * See https://mozilla.github.io/glean/book/user/metrics/string.html#limits.
+   *
+   * @param aValue The string to set the metric to.
+   */
+  void Set(const nsACString& aValue) const;
+
+  /**
+   * **Test-only API**
+   *
+   * Gets the currently stored value as a string.
+   *
+   * This function will attempt to await the last parent-process task (if any)
+   * writing to the the metric's storage engine before returning a value.
+   * This function will not wait for data from child processes.
+   *
+   * This doesn't clear the stored value.
+   * Parent process only. Panics in child processes.
+   *
+   * @param aPingName The (optional) name of the ping to retrieve the metric
+   *        for. Defaults to the first value in `send_in_pings`.
+   *
+   * @return value of the stored metric, or Nothing() if there is no value.
+   */
+  Result<Maybe<nsCString>, nsCString> TestGetValue(
+      const nsACString& aPingName = nsCString()) const;
+
+ private:
+  const uint32_t mId;
+};
+}  // namespace impl
+
+class GleanString final : public nsIGleanString {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIGLEANSTRING
+
+  explicit GleanString(uint32_t aId) : mString(aId){};
+
+ private:
+  virtual ~GleanString() = default;
+
+  const impl::StringMetric mString;
+};
+
+}  // namespace mozilla::glean
+
+#endif /* mozilla_glean_GleanString_h */