1 files changed, 197 insertions, 0 deletions
diff --git a/backend/include/rcc/Support/YAML.h b/backend/include/rcc/Support/YAML.h
new file mode 100644
index 0000000..2e403a9
--- /dev/null
+++ b/backend/include/rcc/Support/YAML.h
@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef RCC_SUPPORT_YAML_H
+#define RCC_SUPPORT_YAML_H
+
+#include "rcc/Support/TextDiagnostic.h"
+
+#include <cstddef>
+#include <cstdint>
+#include <limits>
+#include <optional>
+#include <span>
+#include <string>
+#include <string_view>
+#include <utility>
+#include <vector>
+
+namespace rcc::yaml {
+
+class Parser;
+
+class NodeID final {
+public:
+  constexpr NodeID() noexcept = default;
+
+  [[nodiscard]] constexpr bool isValid() const noexcept {
+    return Value != InvalidValue;
+  }
+
+  [[nodiscard]] constexpr std::uint32_t rawValue() const noexcept {
+    return Value;
+  }
+
+  friend constexpr bool operator==(NodeID Left, NodeID Right) noexcept = default;
+
+private:
+  static constexpr std::uint32_t InvalidValue = std::numeric_limits<std::uint32_t>::max();
+
+  explicit constexpr NodeID(std::uint32_t Value) noexcept : Value(Value) {}
+
+  std::uint32_t Value = InvalidValue;
+
+  friend class Parser;
+  friend class Stream;
+};
+
+enum class NodeKind : std::uint8_t {
+  Null,
+  Scalar,
+  Sequence,
+  Mapping,
+};
+
+enum class ScalarStyle : std::uint8_t {
+  Plain,
+  SingleQuoted,
+  DoubleQuoted,
+  Literal,
+  Folded,
+};
+
+enum class CollectionStyle : std::uint8_t {
+  Block,
+  Flow,
+};
+
+struct MappingEntry final {
+  std::string Key;
+  TextRange KeyRange;
+  NodeID Value;
+};
+
+class Node final {
+public:
+  [[nodiscard]] NodeKind kind() const noexcept {
+    return Kind;
+  }
+
+  [[nodiscard]] const TextRange &range() const noexcept {
+    return Range;
+  }
+
+  [[nodiscard]] ScalarStyle scalarStyle() const noexcept {
+    return ScalarStyleValue;
+  }
+
+  [[nodiscard]] CollectionStyle collectionStyle() const noexcept {
+    return CollectionStyleValue;
+  }
+
+  [[nodiscard]] std::string_view scalar() const noexcept {
+    return Scalar;
+  }
+
+  [[nodiscard]] std::span<const NodeID> sequence() const noexcept {
+    return Sequence;
+  }
+
+  [[nodiscard]] std::span<const MappingEntry> mapping() const noexcept {
+    return Mapping;
+  }
+
+  [[nodiscard]] std::optional<NodeID> mappingValue(std::string_view Key) const noexcept;
+
+private:
+  explicit Node(NodeKind Kind, TextRange Range) : Kind(Kind), Range(Range) {}
+
+  NodeKind Kind;
+  TextRange Range;
+  ScalarStyle ScalarStyleValue = ScalarStyle::Plain;
+  CollectionStyle CollectionStyleValue = CollectionStyle::Block;
+  std::string Scalar;
+  std::vector<NodeID> Sequence;
+  std::vector<MappingEntry> Mapping;
+
+  friend class Parser;
+};
+
+struct Document final {
+  NodeID Root;
+  TextRange Range;
+  bool HasExplicitStart = false;
+  bool HasExplicitEnd = false;
+};
+
+class Stream final {
+public:
+  Stream(const Stream &) = delete;
+  Stream &operator=(const Stream &) = delete;
+  Stream(Stream &&) noexcept = default;
+  Stream &operator=(Stream &&) noexcept = default;
+  ~Stream() = default;
+
+  [[nodiscard]] const TextSource &source() const noexcept {
+    return Source;
+  }
+
+  [[nodiscard]] std::span<const Document> documents() const noexcept {
+    return Documents;
+  }
+
+  [[nodiscard]] const Node *node(NodeID ID) const noexcept;
+  [[nodiscard]] std::size_t nodeCount() const noexcept {
+    return Nodes.size();
+  }
+
+private:
+  Stream(std::string SourceName, std::string SourceText)
+      : Source(std::move(SourceName), std::move(SourceText)) {}
+
+  TextSource Source;
+  std::vector<Node> Nodes;
+  std::vector<Document> Documents;
+
+  friend class Parser;
+};
+
+struct ParseOptions final {
+  std::size_t MaximumDepth = 128;
+  std::size_t MaximumNodes = 1U << 20U;
+};
+
+class ParseResult final {
+public:
+  ParseResult(const ParseResult &) = delete;
+  ParseResult &operator=(const ParseResult &) = delete;
+  ParseResult(ParseResult &&) noexcept = default;
+  ParseResult &operator=(ParseResult &&) noexcept = default;
+  ~ParseResult() = default;
+
+  [[nodiscard]] bool succeeded() const noexcept {
+    return ParsedStream.has_value() && Diagnostics.empty();
+  }
+
+  [[nodiscard]] const Stream *stream() const noexcept {
+    return ParsedStream.has_value() ? ParsedStream.operator->() : nullptr;
+  }
+
+  [[nodiscard]] std::span<const TextDiagnostic> diagnostics() const noexcept {
+    return Diagnostics;
+  }
+
+private:
+  ParseResult() = default;
+
+  std::optional<Stream> ParsedStream;
+  std::vector<TextDiagnostic> Diagnostics;
+
+  friend class Parser;
+};
+
+[[nodiscard]] ParseResult parse(std::string SourceName, std::string SourceText,
+                                ParseOptions Options = {});
+
+} // namespace rcc::yaml
+
+#endif // RCC_SUPPORT_YAML_H