JSSpecCompiler: Add infrastructure to parse <emu-clause> into AST

Author: https://github.com/DanShaders
Commit: db0a03d1fb
Pull-request: https://github.com/SerenityOS/serenity/pull/20632
Reviewed-by: https://github.com/ADKaster ✅

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

@@ -0,0 +1,176 @@
+/*
+ * Copyright (c) 2023, Dan Klishch <danilklishch@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/NonnullOwnPtr.h>
+
+#include "Parser/Lexer.h"
+#include "Parser/SpecParser.h"
+#include "Parser/TextParser.h"
+#include "Parser/XMLUtils.h"
+
+namespace JSSpecCompiler {
+
+ParseErrorOr<AlgorithmStep> AlgorithmStep::create(XML::Node const* node)
+{
+    VERIFY(node->as_element().name == tag_li);
+
+    auto [tokens, substeps] = TRY(tokenize_tree(node, true));
+    AlgorithmStep result { .m_tokens = move(tokens), .m_node = node };
+
+    if (substeps)
+        result.m_substeps = TRY(AlgorithmStepList::create(substeps->as_element())).m_expression;
+
+    result.m_expression = TRY(result.parse());
+    return result;
+}
+
+ParseErrorOr<Tree> AlgorithmStep::parse()
+{
+    TextParser parser(m_tokens, m_node);
+
+    if (m_substeps)
+        return parser.parse_step_with_substeps(RefPtr(m_substeps).release_nonnull());
+    else
+        return parser.parse_step_without_substeps();
+}
+
+ParseErrorOr<AlgorithmStepList> AlgorithmStepList::create(XML::Node::Element const& element)
+{
+    VERIFY(element.name == tag_ol);
+
+    AlgorithmStepList result;
+    auto& steps = result.m_steps;
+
+    Vector<Tree> step_expressions;
+
+    for (auto const& child : element.children) {
+        TRY(child->content.visit(
+            [&](XML::Node::Element const& element) -> ParseErrorOr<void> {
+                if (element.name != tag_li)
+                    return ParseError::create("<emu-alg> <ol> > :not(<li>) should not match any elements"sv, child);
+                steps.append(TRY(AlgorithmStep::create(child)));
+                step_expressions.append(steps.last().m_expression);
+                return {};
+            },
+            [&](XML::Node::Text const&) -> ParseErrorOr<void> {
+                if (!contains_empty_text(child))
+                    return ParseError::create("<emu-alg> <ol> should not have non-empty child text nodes"sv, child);
+                return {};
+            },
+            move(ignore_comments)));
+    }
+
+    result.m_expression = make_ref_counted<TreeList>(move(step_expressions));
+
+    return result;
+}
+
+ParseErrorOr<Algorithm> Algorithm::create(XML::Node const* node)
+{
+    VERIFY(node->as_element().name == tag_emu_alg);
+
+    XML::Node::Element const* steps_list = nullptr;
+    for (auto const& child : node->as_element().children) {
+        TRY(child->content.visit(
+            [&](XML::Node::Element const& element) -> ParseErrorOr<void> {
+                if (element.name == tag_ol) {
+                    if (steps_list != nullptr)
+                        return ParseError::create("<emu-alg> should have exactly one <ol> child"sv, child);
+                    steps_list = &element;
+                    return {};
+                } else {
+                    return ParseError::create("<emu-alg> should not have children other than <ol>"sv, child);
+                }
+            },
+            [&](XML::Node::Text const&) -> ParseErrorOr<void> {
+                if (!contains_empty_text(child))
+                    return ParseError::create("<emu-alg> should not have non-empty child text nodes"sv, child);
+                return {};
+            },
+            move(ignore_comments)));
+    }
+
+    if (steps_list == nullptr)
+        return ParseError::create("<emu-alg> should have exactly one <ol> child"sv, node);
+
+    Algorithm algorithm;
+    algorithm.m_steps = TRY(AlgorithmStepList::create(*steps_list));
+    algorithm.m_tree = algorithm.m_steps.m_expression;
+
+    return algorithm;
+}
+
+ParseErrorOr<Function> Function::create(XML::Node const* element)
+{
+    VERIFY(element->as_element().name == tag_emu_clause);
+
+    Function result;
+    result.m_id = TRY(get_attribute_by_name(element, attribute_id));
+    result.m_name = TRY(get_attribute_by_name(element, attribute_aoid));
+
+    u32 children_count = 0;
+    bool has_definition = false;
+
+    XML::Node const* algorithm_node = nullptr;
+    XML::Node const* prose_node = nullptr;
+
+    for (auto const& child : element->as_element().children) {
+        TRY(child->content.visit(
+            [&](XML::Node::Element const& element) -> ParseErrorOr<void> {
+                ++children_count;
+                if (element.name == tag_h1) {
+                    if (children_count != 1)
+                        return ParseError::create("<h1> should be the first child of a <emu-clause>"sv, child);
+                    TRY(result.parse_definition(child));
+                    has_definition = true;
+                } else if (element.name == tag_p) {
+                    if (prose_node == nullptr)
+                        prose_node = child;
+                } else if (element.name == tag_emu_alg) {
+                    algorithm_node = child;
+                } else {
+                    return ParseError::create("Unknown child of <emu-clause>"sv, child);
+                }
+                return {};
+            },
+            [&](XML::Node::Text const&) -> ParseErrorOr<void> {
+                if (!contains_empty_text(child)) {
+                    return ParseError::create("<emu-clause> should not have non-empty child text nodes"sv, child);
+                }
+                return {};
+            },
+            move(ignore_comments)));
+    }
+
+    if (algorithm_node == nullptr)
+        return ParseError::create("No <emu-alg>"sv, element);
+    if (prose_node == nullptr)
+        return ParseError::create("No prose element"sv, element);
+    if (!has_definition)
+        return ParseError::create("Definition was not found"sv, element);
+
+    result.m_algorithm = TRY(Algorithm::create(algorithm_node));
+    return result;
+}
+
+ParseErrorOr<void> Function::parse_definition(XML::Node const* element)
+{
+    auto tokens = TRY(tokenize_tree(element));
+    TextParser parser(tokens.tokens, element);
+
+    auto [section_number, function_name, arguments] = TRY(parser.parse_definition());
+
+    if (function_name != m_name)
+        return ParseError::create("Function name in definition differs from <emu-clause>[aoid]"sv, element);
+
+    m_section_number = section_number;
+    for (auto const& argument : arguments)
+        m_arguments.append({ argument });
+
+    return {};
+}
+
+}