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ceph-csi/vendor/github.com/antlr4-go/antlr/v4/atn.go

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// Copyright (c) 2012-2022 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
import "sync"
// ATNInvalidAltNumber is used to represent an ALT number that has yet to be calculated or
// which is invalid for a particular struct such as [*antlr.BaseRuleContext]
var ATNInvalidAltNumber int
// ATN represents an “[Augmented Transition Network]”, though general in ANTLR the term
// “Augmented Recursive Transition Network” though there are some descriptions of “[Recursive Transition Network]”
// in existence.
//
// ATNs represent the main networks in the system and are serialized by the code generator and support [ALL(*)].
//
// [Augmented Transition Network]: https://en.wikipedia.org/wiki/Augmented_transition_network
// [ALL(*)]: https://www.antlr.org/papers/allstar-techreport.pdf
// [Recursive Transition Network]: https://en.wikipedia.org/wiki/Recursive_transition_network
type ATN struct {
// DecisionToState is the decision points for all rules, sub-rules, optional
// blocks, ()+, ()*, etc. Each sub-rule/rule is a decision point, and we must track them, so we
// can go back later and build DFA predictors for them. This includes
// all the rules, sub-rules, optional blocks, ()+, ()* etc...
DecisionToState []DecisionState
// grammarType is the ATN type and is used for deserializing ATNs from strings.
grammarType int
// lexerActions is referenced by action transitions in the ATN for lexer ATNs.
lexerActions []LexerAction
// maxTokenType is the maximum value for any symbol recognized by a transition in the ATN.
maxTokenType int
modeNameToStartState map[string]*TokensStartState
modeToStartState []*TokensStartState
// ruleToStartState maps from rule index to starting state number.
ruleToStartState []*RuleStartState
// ruleToStopState maps from rule index to stop state number.
ruleToStopState []*RuleStopState
// ruleToTokenType maps the rule index to the resulting token type for lexer
// ATNs. For parser ATNs, it maps the rule index to the generated bypass token
// type if ATNDeserializationOptions.isGenerateRuleBypassTransitions was
// specified, and otherwise is nil.
ruleToTokenType []int
// ATNStates is a list of all states in the ATN, ordered by state number.
//
states []ATNState
mu sync.Mutex
stateMu sync.RWMutex
edgeMu sync.RWMutex
}
// NewATN returns a new ATN struct representing the given grammarType and is used
// for runtime deserialization of ATNs from the code generated by the ANTLR tool
func NewATN(grammarType int, maxTokenType int) *ATN {
return &ATN{
grammarType: grammarType,
maxTokenType: maxTokenType,
modeNameToStartState: make(map[string]*TokensStartState),
}
}
// NextTokensInContext computes and returns the set of valid tokens that can occur starting
// in state s. If ctx is nil, the set of tokens will not include what can follow
// the rule surrounding s. In other words, the set will be restricted to tokens
// reachable staying within the rule of s.
func (a *ATN) NextTokensInContext(s ATNState, ctx RuleContext) *IntervalSet {
return NewLL1Analyzer(a).Look(s, nil, ctx)
}
// NextTokensNoContext computes and returns the set of valid tokens that can occur starting
// in state s and staying in same rule. [antlr.Token.EPSILON] is in set if we reach end of
// rule.
func (a *ATN) NextTokensNoContext(s ATNState) *IntervalSet {
a.mu.Lock()
defer a.mu.Unlock()
iset := s.GetNextTokenWithinRule()
if iset == nil {
iset = a.NextTokensInContext(s, nil)
iset.readOnly = true
s.SetNextTokenWithinRule(iset)
}
return iset
}
// NextTokens computes and returns the set of valid tokens starting in state s, by
// calling either [NextTokensNoContext] (ctx == nil) or [NextTokensInContext] (ctx != nil).
func (a *ATN) NextTokens(s ATNState, ctx RuleContext) *IntervalSet {
if ctx == nil {
return a.NextTokensNoContext(s)
}
return a.NextTokensInContext(s, ctx)
}
func (a *ATN) addState(state ATNState) {
if state != nil {
state.SetATN(a)
state.SetStateNumber(len(a.states))
}
a.states = append(a.states, state)
}
func (a *ATN) removeState(state ATNState) {
a.states[state.GetStateNumber()] = nil // Just free the memory; don't shift states in the slice
}
func (a *ATN) defineDecisionState(s DecisionState) int {
a.DecisionToState = append(a.DecisionToState, s)
s.setDecision(len(a.DecisionToState) - 1)
return s.getDecision()
}
func (a *ATN) getDecisionState(decision int) DecisionState {
if len(a.DecisionToState) == 0 {
return nil
}
return a.DecisionToState[decision]
}
// getExpectedTokens computes the set of input symbols which could follow ATN
// state number stateNumber in the specified full parse context ctx and returns
// the set of potentially valid input symbols which could follow the specified
// state in the specified context. This method considers the complete parser
// context, but does not evaluate semantic predicates (i.e. all predicates
// encountered during the calculation are assumed true). If a path in the ATN
// exists from the starting state to the RuleStopState of the outermost context
// without Matching any symbols, Token.EOF is added to the returned set.
//
// A nil ctx defaults to ParserRuleContext.EMPTY.
//
// It panics if the ATN does not contain state stateNumber.
func (a *ATN) getExpectedTokens(stateNumber int, ctx RuleContext) *IntervalSet {
if stateNumber < 0 || stateNumber >= len(a.states) {
panic("Invalid state number.")
}
s := a.states[stateNumber]
following := a.NextTokens(s, nil)
if !following.contains(TokenEpsilon) {
return following
}
expected := NewIntervalSet()
expected.addSet(following)
expected.removeOne(TokenEpsilon)
for ctx != nil && ctx.GetInvokingState() >= 0 && following.contains(TokenEpsilon) {
invokingState := a.states[ctx.GetInvokingState()]
rt := invokingState.GetTransitions()[0]
following = a.NextTokens(rt.(*RuleTransition).followState, nil)
expected.addSet(following)
expected.removeOne(TokenEpsilon)
ctx = ctx.GetParent().(RuleContext)
}
if following.contains(TokenEpsilon) {
expected.addOne(TokenEOF)
}
return expected
}