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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2024 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
//
//===----------------------------------------------------------------------===//
/// `AbsoluteSyntaxInfo` represents the information that relates a `RawSyntax`
/// to a source file tree, like its absolute source offset.
struct AbsoluteSyntaxInfo: Sendable {
/// The UTF-8 offset at which the syntax node’s leading trivia start in the source file.
let offset: UInt32
/// Index in parent's layout. Note that this counts `nil` children.
let layoutIndexInParent: UInt32
/// Index of the node when traversing the syntax tree using a depth-first traversal.
/// This skips `nil` children in the parent's layout.
let indexInTree: UInt32
func advancedBySibling(_ raw: RawSyntax?) -> AbsoluteSyntaxInfo {
if let raw {
// '&+' operations are safe because we have the preconditions in 'forRoot(_:)'.
return AbsoluteSyntaxInfo(
offset: offset &+ UInt32(truncatingIfNeeded: raw.totalLength.utf8Length),
layoutIndexInParent: layoutIndexInParent &+ 1,
indexInTree: indexInTree &+ UInt32(truncatingIfNeeded: raw.totalNodes)
)
} else {
return AbsoluteSyntaxInfo(
offset: offset,
layoutIndexInParent: layoutIndexInParent &+ 1,
indexInTree: indexInTree
)
}
}
func advancedToFirstChild() -> AbsoluteSyntaxInfo {
return AbsoluteSyntaxInfo(
offset: offset,
layoutIndexInParent: 0,
indexInTree: indexInTree &+ 1
)
}
static func forRoot(_ raw: RawSyntax) -> AbsoluteSyntaxInfo {
// These checks ensure the safety of the unchecked arithmetic operations in 'advancedBySibling(_:)'.
precondition(raw.totalLength.utf8Length <= UInt32.max, "too long")
precondition(raw.totalNodes <= UInt32.max, "too many nodes")
return AbsoluteSyntaxInfo(
offset: 0,
layoutIndexInParent: 0,
indexInTree: 0
)
}
}
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