runtime/Swift/Sources/Antlr4/FailedPredicateException.swift

/// 
/// Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
/// Use of this file is governed by the BSD 3-clause license that
/// can be found in the LICENSE.txt file in the project root.
/// 


/// 
/// A semantic predicate failed during validation.  Validation of predicates
/// occurs when normally parsing the alternative just like matching a token.
/// Disambiguating predicate evaluation occurs when we test a predicate during
/// prediction.
/// 
public class FailedPredicateException: RecognitionException {
	private let ruleIndex: Int
	private let predicateIndex: Int
	private let predicate: String?

	public init(_ recognizer: Parser, _ predicate: String? = nil, _ message: String? = nil) {
		let s = recognizer.getInterpreter().atn.states[recognizer.getState()]!

		let trans = s.transition(0) as! AbstractPredicateTransition
		if let predex = trans as? PredicateTransition {
			self.ruleIndex = predex.ruleIndex
			self.predicateIndex = predex.predIndex
		}
		else {
			self.ruleIndex = 0
			self.predicateIndex = 0
		}

		self.predicate = predicate

        super.init(recognizer, recognizer.getInputStream()!, recognizer._ctx, FailedPredicateException.formatMessage(predicate, message))
        if let token = try? recognizer.getCurrentToken() {
            setOffendingToken(token)
        }
	}

	public func getRuleIndex() -> Int {
		return ruleIndex
	}

	public func getPredIndex() -> Int {
		return predicateIndex
	}

	public func getPredicate() -> String? {
		return predicate
	}


	private static func formatMessage(_ predicate: String?, _ message: String?) -> String {
		if let message = message {
			return message
		}

        let predstr = predicate ?? "<unknown>"
		return "failed predicate: {\(predstr)}?"
	}
}