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Based on the feedbacks from our early adopters, separating syntax tree analysis with transformation is a common pattern. Thus, we introduce a read-only syntax tree visitor to help the analysis phase. This visitor never alters the content of a tree being visited, in contrast to SyntaxRewriter which always does.
91 lines
2.6 KiB
Swift
91 lines
2.6 KiB
Swift
%{
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from gyb_syntax_support import *
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# -*- mode: Swift -*-
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# Ignore the following admonition it applies to the resulting .swift file only
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def is_visitable(node):
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return not node.is_base() and not node.collection_element
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}%
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//// Automatically Generated From SyntaxFactory.swift.gyb.
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//// Do Not Edit Directly!
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//===------------ SyntaxRewriter.swift - Syntax Rewriter class ------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the SyntaxRewriter, a class that performs a standard walk
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// and tree-rebuilding pattern.
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//
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// Subclassers of this class can override the walking behavior for any syntax
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// node and transform nodes however they like.
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//
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//===----------------------------------------------------------------------===//
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open class SyntaxRewriter {
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public init() {}
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% for node in SYNTAX_NODES:
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% if is_visitable(node):
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open func visit(_ node: ${node.name}) -> ${node.base_type} {
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% cast = ('as! ' + node.base_type) if node.base_type != 'Syntax' else ''
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return visitChildren(node)${cast}
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}
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% end
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% end
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open func visit(_ token: TokenSyntax) -> Syntax {
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return token
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}
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public func visit(_ node: Syntax) -> Syntax {
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switch node.raw.kind {
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case .token: return visit(node as! TokenSyntax)
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% for node in SYNTAX_NODES:
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% if is_visitable(node):
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case .${node.swift_syntax_kind}: return visit(node as! ${node.name})
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% end
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% end
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default: return visitChildren(node)
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}
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}
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func visitChildren(_ node: Syntax) -> Syntax {
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let newLayout = node.children.map { visit($0).raw }
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return Syntax.fromRaw(node.raw.replacingLayout(newLayout))
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}
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}
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open class SyntaxVisitor {
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public init() {}
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% for node in SYNTAX_NODES:
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% if is_visitable(node):
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open func visit(_ node: ${node.name}) {
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visitChildren(node)
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}
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% end
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% end
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open func visit(_ token: TokenSyntax) {}
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public func visit(_ node: Syntax) {
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switch node.raw.kind {
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case .token: visit(node as! TokenSyntax)
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% for node in SYNTAX_NODES:
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% if is_visitable(node):
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case .${node.swift_syntax_kind}: visit(node as! ${node.name})
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% end
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% end
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default: visitChildren(node)
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}
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}
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func visitChildren(_ node: Syntax) {
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node.children.forEach { visit($0) }
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}
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}
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