4 files changed, 166 insertions, 0 deletions
diff --git a/mfbt/TextUtils.h b/mfbt/TextUtils.h
new file mode 100644
index 0000000000..9494296ce1
--- /dev/null
+++ b/mfbt/TextUtils.h
@@ -0,0 +1,58 @@
+/* -*- 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/. */
+
+/* Character/text operations. */
+
+#ifndef mozilla_TextUtils_h
+#define mozilla_TextUtils_h
+
+#include "mozilla/TypeTraits.h"
+
+namespace mozilla {
+
+namespace detail {
+
+template<typename Char>
+class MakeUnsignedChar
+  : public MakeUnsigned<Char>
+{};
+
+template<>
+class MakeUnsignedChar<char16_t>
+{
+public:
+  using Type = char16_t;
+};
+
+template<>
+class MakeUnsignedChar<char32_t>
+{
+public:
+  using Type = char32_t;
+};
+
+} // namespace detail
+
+/**
+ * Returns true iff |aChar| matches [a-zA-Z].
+ *
+ * This function is basically what you thought isalpha was, except its behavior
+ * doesn't depend on the user's current locale.
+ */
+template<typename Char>
+constexpr bool
+IsAsciiAlpha(Char aChar)
+{
+  using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
+  return ('a' <= static_cast<UnsignedChar>(aChar) &&
+          static_cast<UnsignedChar>(aChar) <= 'z') ||
+         ('A' <= static_cast<UnsignedChar>(aChar) &&
+          static_cast<UnsignedChar>(aChar) <= 'Z');
+}
+
+} // namespace mozilla
+
+#endif /* mozilla_TextUtils_h */
diff --git a/mfbt/moz.build b/mfbt/moz.build
index f23a3b6f5d..897a686f48 100644
--- a/mfbt/moz.build
+++ b/mfbt/moz.build
@@ -87,6 +87,7 @@ EXPORTS.mozilla = [
     'StaticAnalysisFunctions.h',
     'TaggedAnonymousMemory.h',
     'TemplateLib.h',
+    'TextUtils.h',
     'ThreadLocal.h',
     'ToString.h',
     'Tuple.h',
diff --git a/mfbt/tests/TestTextUtils.cpp b/mfbt/tests/TestTextUtils.cpp
new file mode 100644
index 0000000000..db481c1389
--- /dev/null
+++ b/mfbt/tests/TestTextUtils.cpp
@@ -0,0 +1,106 @@
+/* -*- 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/. */
+
+#include "mozilla/Assertions.h"
+#include "mozilla/TextUtils.h"
+
+using mozilla::IsAsciiAlpha;
+
+// char
+
+static_assert(!IsAsciiAlpha('@'), "'@' isn't ASCII alpha");
+static_assert('@' == 0x40, "'@' has value 0x40");
+
+static_assert('A' == 0x41, "'A' has value 0x41");
+static_assert(IsAsciiAlpha('A'), "'A' is ASCII alpha");
+static_assert(IsAsciiAlpha('B'), "'B' is ASCII alpha");
+static_assert(IsAsciiAlpha('M'), "'M' is ASCII alpha");
+static_assert(IsAsciiAlpha('Y'), "'Y' is ASCII alpha");
+static_assert(IsAsciiAlpha('Z'), "'Z' is ASCII alpha");
+
+static_assert('Z' == 0x5A, "'Z' has value 0x5A");
+static_assert('[' == 0x5B, "'[' has value 0x5B");
+static_assert(!IsAsciiAlpha('['), "'[' isn't ASCII alpha");
+
+static_assert(!IsAsciiAlpha('`'), "'`' isn't ASCII alpha");
+static_assert('`' == 0x60, "'`' has value 0x60");
+
+static_assert('a' == 0x61, "'a' has value 0x61");
+static_assert(IsAsciiAlpha('a'), "'a' is ASCII alpha");
+static_assert(IsAsciiAlpha('b'), "'b' is ASCII alpha");
+static_assert(IsAsciiAlpha('m'), "'m' is ASCII alpha");
+static_assert(IsAsciiAlpha('y'), "'y' is ASCII alpha");
+static_assert(IsAsciiAlpha('z'), "'z' is ASCII alpha");
+
+static_assert('z' == 0x7A, "'z' has value 0x7A");
+static_assert('{' == 0x7B, "'{' has value 0x7B");
+static_assert(!IsAsciiAlpha('{'), "'{' isn't ASCII alpha");
+
+// char16_t
+
+static_assert(!IsAsciiAlpha(u'@'), "u'@' isn't ASCII alpha");
+static_assert(u'@' == 0x40, "u'@' has value 0x40");
+
+static_assert(u'A' == 0x41, "u'A' has value 0x41");
+static_assert(IsAsciiAlpha(u'A'), "u'A' is ASCII alpha");
+static_assert(IsAsciiAlpha(u'B'), "u'B' is ASCII alpha");
+static_assert(IsAsciiAlpha(u'M'), "u'M' is ASCII alpha");
+static_assert(IsAsciiAlpha(u'Y'), "u'Y' is ASCII alpha");
+static_assert(IsAsciiAlpha(u'Z'), "u'Z' is ASCII alpha");
+
+static_assert(u'Z' == 0x5A, "u'Z' has value 0x5A");
+static_assert(u'[' == 0x5B, "u'[' has value 0x5B");
+static_assert(!IsAsciiAlpha(u'['), "u'[' isn't ASCII alpha");
+
+static_assert(!IsAsciiAlpha(u'`'), "u'`' isn't ASCII alpha");
+static_assert(u'`' == 0x60, "u'`' has value 0x60");
+
+static_assert(u'a' == 0x61, "u'a' has value 0x61");
+static_assert(IsAsciiAlpha(u'a'), "u'a' is ASCII alpha");
+static_assert(IsAsciiAlpha(u'b'), "u'b' is ASCII alpha");
+static_assert(IsAsciiAlpha(u'm'), "u'm' is ASCII alpha");
+static_assert(IsAsciiAlpha(u'y'), "u'y' is ASCII alpha");
+static_assert(IsAsciiAlpha(u'z'), "u'z' is ASCII alpha");
+
+static_assert(u'z' == 0x7A, "u'z' has value 0x7A");
+static_assert(u'{' == 0x7B, "u'{' has value 0x7B");
+static_assert(!IsAsciiAlpha(u'{'), "u'{' isn't ASCII alpha");
+
+// char32_t
+
+static_assert(!IsAsciiAlpha(U'@'), "U'@' isn't ASCII alpha");
+static_assert(U'@' == 0x40, "U'@' has value 0x40");
+
+static_assert(U'A' == 0x41, "U'A' has value 0x41");
+static_assert(IsAsciiAlpha(U'A'), "U'A' is ASCII alpha");
+static_assert(IsAsciiAlpha(U'B'), "U'B' is ASCII alpha");
+static_assert(IsAsciiAlpha(U'M'), "U'M' is ASCII alpha");
+static_assert(IsAsciiAlpha(U'Y'), "U'Y' is ASCII alpha");
+static_assert(IsAsciiAlpha(U'Z'), "U'Z' is ASCII alpha");
+
+static_assert(U'Z' == 0x5A, "U'Z' has value 0x5A");
+static_assert(U'[' == 0x5B, "U'[' has value 0x5B");
+static_assert(!IsAsciiAlpha(U'['), "U'[' isn't ASCII alpha");
+
+static_assert(!IsAsciiAlpha(U'`'), "U'`' isn't ASCII alpha");
+static_assert(U'`' == 0x60, "U'`' has value 0x60");
+
+static_assert(U'a' == 0x61, "U'a' has value 0x61");
+static_assert(IsAsciiAlpha(U'a'), "U'a' is ASCII alpha");
+static_assert(IsAsciiAlpha(U'b'), "U'b' is ASCII alpha");
+static_assert(IsAsciiAlpha(U'm'), "U'm' is ASCII alpha");
+static_assert(IsAsciiAlpha(U'y'), "U'y' is ASCII alpha");
+static_assert(IsAsciiAlpha(U'z'), "U'z' is ASCII alpha");
+
+static_assert(U'z' == 0x7A, "U'z' has value 0x7A");
+static_assert(U'{' == 0x7B, "U'{' has value 0x7B");
+static_assert(!IsAsciiAlpha(U'{'), "U'{' isn't ASCII alpha");
+
+int
+main()
+{
+  return 0;
+}
diff --git a/mfbt/tests/moz.build b/mfbt/tests/moz.build
index f96117e038..bd25ab1d0b 100644
--- a/mfbt/tests/moz.build
+++ b/mfbt/tests/moz.build
@@ -42,6 +42,7 @@ CppUnitTests([
     'TestSHA1',
     'TestSplayTree',
     'TestTemplateLib',
+    'TestTextUtils',
     'TestTuple',
     'TestTypedEnum',
     'TestTypeTraits',