[libSyntax] Restructure RawSyntax to more closely resemble the SwiftSyntax implementation

include/swift/Syntax/AbsoluteRawSyntax.h

@@ -0,0 +1,244 @@
+//===--- AbsoluteRawSyntax.h ------------------------------------*- C++ -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SWIFT_SYNTAX_ABSOLUTERAWSYNTAX_H
+#define SWIFT_SYNTAX_ABSOLUTERAWSYNTAX_H
+
+#include "swift/Basic/SourceLoc.h"
+#include "swift/Syntax/RawSyntax.h"
+
+namespace swift {
+namespace syntax {
+
+/// Type-safe wrapper around a \c size_t that describes a node's index in its
+/// tree. This represents the index at which the node will be encountered during
+/// a depth-first traversal of the tree.
+class SyntaxIndexInTree {
+  size_t IndexInTree;
+
+  explicit SyntaxIndexInTree(size_t IndexInTree) : IndexInTree(IndexInTree) {}
+
+public:
+  static SyntaxIndexInTree zero() { return SyntaxIndexInTree(0); }
+
+  /// Assuming that this index points to the start of \p Raw, advance it so that
+  /// it points to the next sibling of \p Raw.
+  SyntaxIndexInTree advancedBy(const RC<RawSyntax> &Raw) const;
+
+  /// Assuming that this index points to the next sibling of \p Raw, reverse it
+  /// so that it points to the start of \p Raw.
+  SyntaxIndexInTree reversedBy(const RC<RawSyntax> &Raw) const;
+
+  /// Advance this index to point to its first immediate child.
+  SyntaxIndexInTree advancedToFirstChild() const;
+};
+
+/// A syntax identifier that globally identifies a \c Syntax node.
+/// In contrast to \c NodeId of \c RawSyntax, this also takes into account the
+/// node's position in the tree. For example, a source file may contain two
+/// int literals with value 0. The corresponding \c RawSyntax nodes can share
+/// the same \c NodeId. However, because the literals occur in different
+/// locations of the syntax tree, their \c SyntaxIdentifiers are different.
+class SyntaxIdentifier {
+public:
+  using RootIdType = size_t;
+
+private:
+  static std::atomic<RootIdType> NextUnusedRootId;
+
+  /// An integer that identifies the tree in which the node represented by this
+  /// identifier lives.
+  RootIdType RootId;
+
+  /// The position of the node represented by this identifier in the syntax
+  /// tree.
+  SyntaxIndexInTree IndexInTree;
+
+public:
+  SyntaxIdentifier(RootIdType RootId, SyntaxIndexInTree IndexInTree)
+      : RootId(RootId), IndexInTree(IndexInTree) {
+    assert(RootId < NextUnusedRootId && "New RootIds should only be created "
+                                        "using the newRoot constructor.");
+  }
+
+  /// Create a SyntaxIdentifier that refers to the root of a new syntax tree.
+  static SyntaxIdentifier newRoot() {
+    return SyntaxIdentifier(NextUnusedRootId++, SyntaxIndexInTree::zero());
+  }
+
+  RootIdType getRootId() const { return RootId; }
+  SyntaxIndexInTree getIndexInTree() const { return IndexInTree; }
+
+  /// Assuming that this identifier points to the start of \p Raw, advance it so
+  /// that it points to the next sibling of \p Raw.
+  SyntaxIdentifier advancedBy(const RC<RawSyntax> &Raw) const {
+    auto NewIndexInTree = IndexInTree.advancedBy(Raw);
+    return SyntaxIdentifier(RootId, NewIndexInTree);
+  }
+
+  /// Assuming that this identifier points to the next sibling of \p Raw,
+  /// reverse it so that it points to the start of \p Raw.
+  SyntaxIdentifier reversedBy(const RC<RawSyntax> &Raw) const {
+    auto NewIndexInTree = IndexInTree.reversedBy(Raw);
+    return SyntaxIdentifier(RootId, NewIndexInTree);
+  }
+
+  /// Get the identifier of the first immediate child.
+  SyntaxIdentifier advancedToFirstChild() const {
+    auto NewIndexInTree = IndexInTree.advancedToFirstChild();
+    return SyntaxIdentifier(RootId, NewIndexInTree);
+  }
+};
+
+/// Represents a node's position in a syntax tree, described by its overal
+/// textual offset and the position within its parent.
+class AbsoluteSyntaxPosition {
+public:
+  using OffsetType = uint32_t;
+  using IndexInParentType = uint32_t;
+
+private:
+  /// The text offset where this node starts within its syntax tree, counted in
+  /// UTF-8 bytes.
+  OffsetType Offset;
+
+  /// The node's index within its parent, i.e.
+  /// `node.parent.childAt(IndexInParent) = node`.
+  IndexInParentType IndexInParent;
+
+public:
+  AbsoluteSyntaxPosition(OffsetType Offset, IndexInParentType IndexInParent)
+      : Offset(Offset), IndexInParent(IndexInParent) {}
+
+  /// Create a new \c AbsoluteSyntaxPosition that refers to the root of a syntax
+  /// tree.
+  static AbsoluteSyntaxPosition forRoot() {
+    return AbsoluteSyntaxPosition(0, 0);
+  }
+
+  OffsetType getOffset() const { return Offset; }
+  IndexInParentType getIndexInParent() const { return IndexInParent; }
+
+  /// Assuming that this position points to the start of \p Raw, advance it so
+  /// that it points to the next sibling of \p Raw.
+  AbsoluteSyntaxPosition advancedBy(const RC<RawSyntax> &Raw) const;
+
+  /// Assuming that this position points to the next sibling of \p Raw, reverse
+  /// it so that it points to the start of \p Raw.
+  AbsoluteSyntaxPosition reversedBy(const RC<RawSyntax> &Raw) const;
+
+  /// Get the position of the node's first immediate child.
+  AbsoluteSyntaxPosition advancedToFirstChild() const {
+    return AbsoluteSyntaxPosition(Offset, 0);
+  }
+};
+
+/// A type-safe wrapper that describes a node's textual position within a source
+/// file, represented by its UTF-8 byte offset from the start.
+class AbsoluteOffsetPosition {
+  AbsoluteSyntaxPosition::OffsetType Offset;
+
+public:
+  explicit AbsoluteOffsetPosition(AbsoluteSyntaxPosition::OffsetType Offset)
+      : Offset(Offset) {}
+  AbsoluteOffsetPosition(AbsoluteSyntaxPosition Position)
+      : Offset(Position.getOffset()) {}
+
+  AbsoluteSyntaxPosition::OffsetType getOffset() const { return Offset; }
+
+  /// Return a position that has been advanced by \p Advance UTF-8 bytes.s
+  AbsoluteOffsetPosition advancedBy(int Advance) {
+    return AbsoluteOffsetPosition(Offset + Advance);
+  }
+};
+
+/// Various information that enrich a \c RawSyntax node with information on how
+/// it's located within the syntax tree.
+class AbsoluteSyntaxInfo {
+  AbsoluteSyntaxPosition Position;
+  SyntaxIdentifier NodeId;
+
+public:
+  AbsoluteSyntaxInfo(AbsoluteSyntaxPosition Position, SyntaxIdentifier NodeId)
+      : Position(Position), NodeId(NodeId) {}
+
+  static AbsoluteSyntaxInfo forRoot() {
+    return AbsoluteSyntaxInfo(AbsoluteSyntaxPosition::forRoot(),
+                              SyntaxIdentifier::newRoot());
+  }
+
+  AbsoluteSyntaxPosition getPosition() const { return Position; }
+  SyntaxIdentifier getNodeId() const { return NodeId; }
+
+  /// Assuming that this info points to the start of \p Raw, advance it so
+  /// that it points to the next sibling of \p Raw.
+  AbsoluteSyntaxInfo advancedBy(const RC<RawSyntax> &Raw) const {
+    auto NewNodeId = NodeId.advancedBy(Raw);
+    auto NewPosition = Position.advancedBy(Raw);
+    return AbsoluteSyntaxInfo(NewPosition, NewNodeId);
+  }
+
+  /// Assuming that this info points to the next sibling of \p Raw, reverse
+  /// it so that it points to the start of \p Raw.
+  AbsoluteSyntaxInfo reversedBy(const RC<RawSyntax> &Raw) const {
+    auto NewNodeId = NodeId.reversedBy(Raw);
+    auto NewPosition = Position.reversedBy(Raw);
+    return AbsoluteSyntaxInfo(NewPosition, NewNodeId);
+  }
+
+  /// Get the information of the node's first immediate child.
+  AbsoluteSyntaxInfo advancedToFirstChild() const {
+    auto NewNodeId = NodeId.advancedToFirstChild();
+    auto NewPosition = Position.advancedToFirstChild();
+    return AbsoluteSyntaxInfo(NewPosition, NewNodeId);
+  }
+};
+
+/// A \c RawSyntax node that is enrichted with information of its position
+/// within the syntax tree it lives in.
+struct AbsoluteRawSyntax {
+  const RC<RawSyntax> Raw;
+  const AbsoluteSyntaxInfo Info;
+
+public:
+  AbsoluteRawSyntax(const RC<RawSyntax> &Raw, AbsoluteSyntaxInfo Info)
+      : Raw(Raw), Info(Info) {}
+
+  /// Construct a \c AbsoluteRawSyntax for a \c RawSyntax node that represents
+  /// the syntax tree's root.
+  static AbsoluteRawSyntax forRoot(const RC<RawSyntax> &Raw) {
+    return AbsoluteRawSyntax(Raw, AbsoluteSyntaxInfo::forRoot());
+  }
+
+  const RC<RawSyntax> &getRaw() const { return Raw; }
+
+  AbsoluteSyntaxInfo getInfo() const { return Info; }
+
+  /// Get the position at which the leading triva of this node starts.
+  AbsoluteSyntaxPosition getPosition() const { return Info.getPosition(); };
+
+  SyntaxIdentifier getNodeId() const { return Info.getNodeId(); };
+
+  AbsoluteSyntaxPosition::IndexInParentType getIndexInParent() const {
+    return getPosition().getIndexInParent();
+  }
+};
+
+} // end namespace syntax
+} // end namespace swift
+
+namespace llvm {
+raw_ostream &operator<<(raw_ostream &OS,
+                        swift::syntax::AbsoluteOffsetPosition Pos);
+} // end namespace llvm
+
+#endif // SWIFT_SYNTAX_ABSOLUTERAWSYNTAX_H