JSSpecCompiler: Add functions for splitting node contents into tokens

Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Parser/XMLUtils.cpp

@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2023, Dan Klishch <danilklishch@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/NonnullOwnPtr.h>
+#include <LibXML/DOM/Node.h>
+
+#include "Parser/XMLUtils.h"
+
+namespace JSSpecCompiler {
+
+bool contains_empty_text(XML::Node const* node)
+{
+    return node->as_text().builder.string_view().trim_whitespace().is_empty();
+}
+
+ParseErrorOr<StringView> get_attribute_by_name(XML::Node const* node, StringView attribute_name)
+{
+    auto const& attribute = node->as_element().attributes.get(attribute_name);
+
+    if (!attribute.has_value())
+        return ParseError::create(String::formatted("Attribute {} is not present", attribute_name), node);
+    return attribute.value();
+}
+
+ParseErrorOr<StringView> get_text_contents(XML::Node const* node)
+{
+    auto const& children = node->as_element().children;
+
+    if (children.size() != 1 || !children[0]->is_text())
+        return ParseError::create("Expected single text node in a child list of the node"sv, node);
+    return children[0]->as_text().builder.string_view();
+}
+
+ParseErrorOr<XML::Node const*> get_only_child(XML::Node const* element, StringView tag_name)
+{
+    XML::Node const* result = nullptr;
+
+    for (auto const& child : element->as_element().children) {
+        TRY(child->content.visit(
+            [&](XML::Node::Element const& element) -> ParseErrorOr<void> {
+                if (element.name != tag_name)
+                    return ParseError::create(String::formatted("Expected child with the tag name {} but found {}", tag_name, element.name), child);
+                if (result != nullptr)
+                    return ParseError::create("Element must have only one child"sv, child);
+                result = child;
+                return {};
+            },
+            [&](XML::Node::Text const&) -> ParseErrorOr<void> {
+                if (!contains_empty_text(child))
+                    return ParseError::create("Element should not have non-empty child text nodes"sv, element);
+                return {};
+            },
+            move(ignore_comments)));
+    }
+
+    if (result == nullptr)
+        return ParseError::create(String::formatted("Element must have only one child"), element);
+    return result;
+}
+
+}