swift-pterodactyl / Sources / PterodactylSyntax / VisibleNodeSearching.swift

// SPDX-FileCopyrightText: 2026 The Project Pterodactyl Developers
//
// SPDX-License-Identifier: MPL-2.0

import Foundation

public enum ArraySymmetry {
	case identity
	case reverse
}

extension Array {
	fileprivate func apply(symmetry: ArraySymmetry) -> any Collection<Element> {
		switch symmetry {
		case .identity: self
		case .reverse: reversed()
		}
	}
}

public protocol NodeSearching {
	func firstToken(under symmetry: ArraySymmetry, satisfying predicate: (Token) -> Bool) -> SyntaxTokenCursor?
}

extension NodeSearching {
	public func utf16RangeClamped(to predicate: (Token) -> Bool) -> Range<Int>? {
		guard
			let first = firstToken(under: .identity, satisfying: predicate),
			let last = firstToken(under: .reverse, satisfying: predicate)
		else { return nil }
		return first.utf16Range.lowerBound..<last.utf16Range.upperBound
	}

	public var visibleUtf16Range: Range<Int>? {
		utf16RangeClamped(to: \.kind.isVisible)
	}

	public var nontrivialUtf16Range: Range<Int>? {
		utf16RangeClamped { token in
			!token.kind.isTrivia
		}
	}
}

extension SyntaxTokenCursor: NodeSearching {
	public func firstToken(under symmetry: ArraySymmetry, satisfying predicate: (Token) -> Bool) -> SyntaxTokenCursor? {
		if predicate(token) { self } else { nil }
	}
}

extension SyntaxTreeCursor.Child: NodeSearching {
	public func firstToken(under symmetry: ArraySymmetry, satisfying predicate: (Token) -> Bool) -> SyntaxTokenCursor? {
		switch self {
		case .token(let syntaxTokenCursor): syntaxTokenCursor.firstToken(under: symmetry, satisfying: predicate)
		case .tree(let syntaxTreeCursor): syntaxTreeCursor.firstToken(under: symmetry, satisfying: predicate)
		}
	}
}

extension SyntaxTreeCursor: NodeSearching {
	public func firstToken(under symmetry: ArraySymmetry, satisfying predicate: (Token) -> Bool) -> SyntaxTokenCursor? {
		for child in children.apply(symmetry: symmetry) {
			if let first = child.firstToken(under: symmetry, satisfying: predicate) { return first }
		}

		return nil
	}
}