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1// SPDX-FileCopyrightText: 2025 The Project Pterodactyl Developers
2//
3// SPDX-License-Identifier: MPL-2.0
4
5import Foundation
6
7/// This is an abstraction of grammatical productions.
8public protocol Grammar: Sendable {
9 /// The kinds of tree that the production produces.
10 static var kinds: [SyntaxTreeKind] { get }
11
12 /// Indicates whether the current parser state is consistent with the grammatical production starting here. When a given grammatical element is optional, this can be used to avoid backtracking. This is a *precondition* for parsing.
13 static func precondition(_ parser: inout Parser) -> Bool
14
15 /// Parse the grammatical production, assuming the precondition indicated by ``precondition(_:)``. This function should not be called outside this module (instead, use ``parse(_:recovery:)`` and ``tryParse(_:recovery:)``.
16 static func inside(_ parser: inout Parser, recovery: Set<TokenKind>) -> ParseResult
17}
18
19extension Grammar {
20 public static func tryParse(_ parser: inout Parser, recovery: Set<TokenKind>) -> Bool {
21 guard !parser.isEndOfFile && precondition(&parser) else { return false }
22 parse(&parser, recovery: recovery)
23 return true
24 }
25
26 public static func parse(_ parser: inout Parser, recovery: Set<TokenKind>) {
27 let mark = parser.builder.open()
28 let result = inside(&parser, recovery: recovery)
29 parser.builder.close(mark: mark, kind: result.kind, metadata: result.metadata)
30 }
31}
32
33public struct ParseResult {
34 public var kind: SyntaxTreeKind
35 public var metadata: SyntaxTreeMetadata? = nil
36
37 public init(kind: SyntaxTreeKind, metadata: SyntaxTreeMetadata? = nil) {
38 self.kind = kind
39 self.metadata = metadata
40 }
41}
42