tools/SwiftSyntax/SyntaxRewriter.swift.gyb

%{
  from gyb_syntax_support import *
  # -*- mode: Swift -*-
  # Ignore the following admonition it applies to the resulting .swift file only
}%
//// Automatically Generated From SyntaxFactory.swift.gyb.
//// Do Not Edit Directly!
//===------------ SyntaxRewriter.swift - Syntax Rewriter class ------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 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
//
//===----------------------------------------------------------------------===//
//
// This file defines the SyntaxRewriter, a class that performs a standard walk
// and tree-rebuilding pattern.
//
// Subclassers of this class can override the walking behavior for any syntax
// node and transform nodes however they like.
//
//===----------------------------------------------------------------------===//

open class SyntaxRewriter {
  public init() {}
% for node in SYNTAX_NODES:
%   if is_visitable(node):
  open func visit(_ node: ${node.name}) -> ${node.base_type} {
%   cast = ('as! ' + node.base_type) if node.base_type != 'Syntax' else ''
    return visitChildren(node) ${cast}
  }

%   end
% end

  open func visit(_ token: TokenSyntax) -> Syntax {
    return token
  }

  /// The function called before visiting the node and its descendents.
  ///   - node: the node we are about to visit.
  open func visitPre(_ node: Syntax) {}

  /// Override point to choose custom visitation dispatch instead of the
  /// specialized `visit(_:)` methods. Use this instead of those methods if
  /// you intend to dynamically dispatch rewriting behavior.
  /// - note: If this method returns a non-nil result, the specialized
  ///         `visit(_:)` methods will not be called for this node.
  open func visitAny(_ node: Syntax) -> Syntax? {
    return nil
  }

  /// The function called after visting the node and its descendents.
  ///   - node: the node we just finished visiting.
  open func visitPost(_ node: Syntax) {}

  public func visit(_ node: Syntax) -> Syntax {
    visitPre(node)
    defer { visitPost(node) }

    // If the global visitor returned non-nil, skip specialized dispatch.
    if let newNode = visitAny(node) {
      return newNode
    }

    switch node.raw.kind {
    case .token: return visit(node as! TokenSyntax)
% for node in SYNTAX_NODES:
%   if is_visitable(node):
    case .${node.swift_syntax_kind}: return visit(node as! ${node.name})
%   end
% end
    default: return visitChildren(node)
    }
  }

  func visitChildren(_ node: Syntax) -> Syntax {
    // Visit all children of this node, returning `nil` if child is not
    // present. This will ensure that there are always the same number
    // of children after transforming.
    let newLayout = (0..<node.numberOfChildren).map { (i: Int) -> RawSyntax? in
      guard let child = node.child(at: i) else { return nil }
      return visit(child).raw
    }

    // Sanity check, ensure the new children are the same length.
    assert(newLayout.count == node.raw.layout.count)

    return makeSyntax(node.raw.replacingLayout(newLayout))
  }
}

open class SyntaxVisitor {
    public init() {}
% for node in SYNTAX_NODES:
%   if is_visitable(node):
  open func visit(_ node: ${node.name}) {
    visitChildren(node)
  }
%   end
% end

  open func visit(_ token: TokenSyntax) {}

  /// The function called before visiting the node and its descendents.
  ///   - node: the node we are about to visit.
  open func visitPre(_ node: Syntax) {}

  /// The function called after visting the node and its descendents.
  ///   - node: the node we just finished visiting.
  open func visitPost(_ node: Syntax) {}

  public func visit(_ node: Syntax) {
    visitPre(node)
    defer { visitPost(node) }
    switch node.raw.kind {
    case .token: visit(node as! TokenSyntax)
% for node in SYNTAX_NODES:
%   if is_visitable(node):
    case .${node.swift_syntax_kind}: visit(node as! ${node.name})
%   end
% end
    default: visitChildren(node)
    }
  }

  func visitChildren(_ node: Syntax) {
    node.children.forEach { visit($0) }
  }
}