LibWeb: Implement custom element name validation

2 files changed, 91 insertions, 0 deletions

diff --git a/Userland/Libraries/LibWeb/HTML/CustomElements/CustomElementName.cpp b/Userland/Libraries/LibWeb/HTML/CustomElements/CustomElementName.cpp
new file mode 100644
index 0000000000..340fc51f3f
--- /dev/null
+++ b/Userland/Libraries/LibWeb/HTML/CustomElements/CustomElementName.cpp
@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2023, Srikavin Ramkumar <me@srikavin.me>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/StringView.h>
+#include <AK/Utf8View.h>
+#include <LibWeb/HTML/CustomElements/CustomElementName.h>
+
+namespace Web::HTML {
+
+// https://html.spec.whatwg.org/multipage/custom-elements.html#custom-elements-core-concepts:prod-pcenchar
+static bool is_pcen_char(u32 code_point)
+{
+    return code_point == '-'
+        || code_point == '.'
+        || (code_point >= '0' && code_point <= '9')
+        || code_point == '_'
+        || (code_point >= 'a' && code_point <= 'z')
+        || code_point == 0xb7
+        || (code_point >= 0xc0 && code_point <= 0xd6)
+        || (code_point >= 0xd8 && code_point <= 0xf6)
+        || (code_point >= 0xf8 && code_point <= 0x37d)
+        || (code_point >= 0x37f && code_point <= 0x1fff)
+        || (code_point >= 0x200c && code_point <= 0x200d)
+        || (code_point >= 0x203f && code_point <= 0x2040)
+        || (code_point >= 0x2070 && code_point <= 0x218f)
+        || (code_point >= 0x2c00 && code_point <= 0x2fef)
+        || (code_point >= 0x3001 && code_point <= 0xD7ff)
+        || (code_point >= 0xf900 && code_point <= 0xfdcf)
+        || (code_point >= 0xfdf0 && code_point <= 0xfffd)
+        || (code_point >= 0x10000 && code_point <= 0xeffff);
+}
+
+// https://html.spec.whatwg.org/multipage/custom-elements.html#valid-custom-element-name
+bool is_valid_custom_element_name(StringView name)
+{
+    // name must not be any of the following:
+    if (name.is_one_of(
+            "annotation-xml"sv,
+            "color-profile"sv,
+            "font-face"sv,
+            "font-face-src"sv,
+            "font-face-uri"sv,
+            "font-face-format"sv,
+            "font-face-name"sv,
+            "missing-glyph"sv)) {
+        return false;
+    }
+
+    // name must match the PotentialCustomElementName production:
+    // PotentialCustomElementName ::=
+    //      [a-z] (PCENChar)* '-' (PCENChar)*
+
+    auto code_points = Utf8View { name };
+    auto it = code_points.begin();
+
+    if (code_points.is_empty() || *it < 'a' || *it > 'z')
+        return false;
+
+    ++it;
+
+    bool found_hyphen = false;
+
+    for (; it != code_points.end(); ++it) {
+        if (!is_pcen_char(*it))
+            return false;
+        if (*it == '-')
+            found_hyphen = true;
+    }
+
+    return found_hyphen;
+}
+
+}
diff --git a/Userland/Libraries/LibWeb/HTML/CustomElements/CustomElementName.h b/Userland/Libraries/LibWeb/HTML/CustomElements/CustomElementName.h
new file mode 100644
index 0000000000..b16ea325cd
--- /dev/null
+++ b/Userland/Libraries/LibWeb/HTML/CustomElements/CustomElementName.h
@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2023, Srikavin Ramkumar <me@srikavin.me>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/StringView.h>
+
+namespace Web::HTML {
+
+bool is_valid_custom_element_name(StringView name);
+
+}