errors.go

// 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.

package antlr

// The root of the ANTLR exception hierarchy. In general, ANTLR tracks just
//  3 kinds of errors: prediction errors, failed predicate errors, and
//  mismatched input errors. In each case, the parser knows where it is
//  in the input, where it is in the ATN, the rule invocation stack,
//  and what kind of problem occurred.

type RecognitionException interface {
	GetOffendingToken() Token
	GetMessage() string
	GetInputStream() IntStream
}

type BaseRecognitionException struct {
	message        string
	recognizer     Recognizer
	offendingToken Token
	offendingState int
	ctx            RuleContext
	input          IntStream
}

func NewBaseRecognitionException(message string, recognizer Recognizer, input IntStream, ctx RuleContext) *BaseRecognitionException {

	// todo
	//	Error.call(this)
	//
	//	if (!!Error.captureStackTrace) {
	//        Error.captureStackTrace(this, RecognitionException)
	//	} else {
	//		stack := NewError().stack
	//	}
	// TODO may be able to use - "runtime" func Stack(buf []byte, all bool) int

	t := new(BaseRecognitionException)

	t.message = message
	t.recognizer = recognizer
	t.input = input
	t.ctx = ctx
	// The current {@link Token} when an error occurred. Since not all streams
	// support accessing symbols by index, we have to track the {@link Token}
	// instance itself.
	t.offendingToken = nil
	// Get the ATN state number the parser was in at the time the error
	// occurred. For {@link NoViableAltException} and
	// {@link LexerNoViableAltException} exceptions, this is the
	// {@link DecisionState} number. For others, it is the state whose outgoing
	// edge we couldn't Match.
	t.offendingState = -1
	if t.recognizer != nil {
		t.offendingState = t.recognizer.GetState()
	}

	return t
}

func (b *BaseRecognitionException) GetMessage() string {
	return b.message
}

func (b *BaseRecognitionException) GetOffendingToken() Token {
	return b.offendingToken
}

func (b *BaseRecognitionException) GetInputStream() IntStream {
	return b.input
}

// <p>If the state number is not known, b method returns -1.</p>

//
// Gets the set of input symbols which could potentially follow the
// previously Matched symbol at the time b exception was panicn.
//
// <p>If the set of expected tokens is not known and could not be computed,
// b method returns {@code nil}.</p>
//
// @return The set of token types that could potentially follow the current
// state in the ATN, or {@code nil} if the information is not available.
// /
func (b *BaseRecognitionException) getExpectedTokens() *IntervalSet {
	if b.recognizer != nil {
		return b.recognizer.GetATN().getExpectedTokens(b.offendingState, b.ctx)
	}

	return nil
}

func (b *BaseRecognitionException) String() string {
	return b.message
}

type LexerNoViableAltException struct {
	*BaseRecognitionException

	startIndex     int
	deadEndConfigs ATNConfigSet
}

func NewLexerNoViableAltException(lexer Lexer, input CharStream, startIndex int, deadEndConfigs ATNConfigSet) *LexerNoViableAltException {

	l := new(LexerNoViableAltException)

	l.BaseRecognitionException = NewBaseRecognitionException("", lexer, input, nil)

	l.startIndex = startIndex
	l.deadEndConfigs = deadEndConfigs

	return l
}

func (l *LexerNoViableAltException) String() string {
	symbol := ""
	if l.startIndex >= 0 && l.startIndex < l.input.Size() {
		symbol = l.input.(CharStream).GetTextFromInterval(NewInterval(l.startIndex, l.startIndex))
	}
	return "LexerNoViableAltException" + symbol
}

type NoViableAltException struct {
	*BaseRecognitionException

	startToken     Token
	offendingToken Token
	ctx            ParserRuleContext
	deadEndConfigs ATNConfigSet
}

// Indicates that the parser could not decide which of two or more paths
// to take based upon the remaining input. It tracks the starting token
// of the offending input and also knows where the parser was
// in the various paths when the error. Reported by ReportNoViableAlternative()
//
func NewNoViableAltException(recognizer Parser, input TokenStream, startToken Token, offendingToken Token, deadEndConfigs ATNConfigSet, ctx ParserRuleContext) *NoViableAltException {

	if ctx == nil {
		ctx = recognizer.GetParserRuleContext()
	}

	if offendingToken == nil {
		offendingToken = recognizer.GetCurrentToken()
	}

	if startToken == nil {
		startToken = recognizer.GetCurrentToken()
	}

	if input == nil {
		input = recognizer.GetInputStream().(TokenStream)
	}

	n := new(NoViableAltException)
	n.BaseRecognitionException = NewBaseRecognitionException("", recognizer, input, ctx)

	// Which configurations did we try at input.Index() that couldn't Match
	// input.LT(1)?//
	n.deadEndConfigs = deadEndConfigs
	// The token object at the start index the input stream might
	// not be buffering tokens so get a reference to it. (At the
	// time the error occurred, of course the stream needs to keep a
	// buffer all of the tokens but later we might not have access to those.)
	n.startToken = startToken
	n.offendingToken = offendingToken

	return n
}

type InputMisMatchException struct {
	*BaseRecognitionException
}

// This signifies any kind of mismatched input exceptions such as
// when the current input does not Match the expected token.
//
func NewInputMisMatchException(recognizer Parser) *InputMisMatchException {

	i := new(InputMisMatchException)
	i.BaseRecognitionException = NewBaseRecognitionException("", recognizer, recognizer.GetInputStream(), recognizer.GetParserRuleContext())

	i.offendingToken = recognizer.GetCurrentToken()

	return i

}

// 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.

type FailedPredicateException struct {
	*BaseRecognitionException

	ruleIndex      int
	predicateIndex int
	predicate      string
}

func NewFailedPredicateException(recognizer Parser, predicate string, message string) *FailedPredicateException {

	f := new(FailedPredicateException)

	f.BaseRecognitionException = NewBaseRecognitionException(f.formatMessage(predicate, message), recognizer, recognizer.GetInputStream(), recognizer.GetParserRuleContext())

	s := recognizer.GetInterpreter().atn.states[recognizer.GetState()]
	trans := s.GetTransitions()[0]
	if trans2, ok := trans.(*PredicateTransition); ok {
		f.ruleIndex = trans2.ruleIndex
		f.predicateIndex = trans2.predIndex
	} else {
		f.ruleIndex = 0
		f.predicateIndex = 0
	}
	f.predicate = predicate
	f.offendingToken = recognizer.GetCurrentToken()

	return f
}

func (f *FailedPredicateException) formatMessage(predicate, message string) string {
	if message != "" {
		return message
	}

	return "failed predicate: {" + predicate + "}?"
}

type ParseCancellationException struct {
}

func NewParseCancellationException() *ParseCancellationException {
	//	Error.call(this)
	//	Error.captureStackTrace(this, ParseCancellationException)
	return new(ParseCancellationException)
}