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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
type DFA struct {
// atnStartState is the ATN state in which this was created
atnStartState DecisionState
decision int
// states is all the DFA states. Use Map to get the old state back; Set can only
// indicate whether it is there. Go maps implement key hash collisions and so on and are very
// good, but the DFAState is an object and can't be used directly as the key as it can in say JAva
// amd C#, whereby if the hashcode is the same for two objects, then Equals() is called against them
// to see if they really are the same object.
//
//
states *JStore[*DFAState, *ObjEqComparator[*DFAState]]
numstates int
s0 *DFAState
// precedenceDfa is the backing field for isPrecedenceDfa and setPrecedenceDfa.
// True if the DFA is for a precedence decision and false otherwise.
precedenceDfa bool
}
func NewDFA(atnStartState DecisionState, decision int) *DFA {
dfa := &DFA{
atnStartState: atnStartState,
decision: decision,
states: NewJStore[*DFAState, *ObjEqComparator[*DFAState]](&ObjEqComparator[*DFAState]{}),
}
if s, ok := atnStartState.(*StarLoopEntryState); ok && s.precedenceRuleDecision {
dfa.precedenceDfa = true
dfa.s0 = NewDFAState(-1, NewBaseATNConfigSet(false))
dfa.s0.isAcceptState = false
dfa.s0.requiresFullContext = false
}
return dfa
}
// getPrecedenceStartState gets the start state for the current precedence and
// returns the start state corresponding to the specified precedence if a start
// state exists for the specified precedence and nil otherwise. d must be a
// precedence DFA. See also isPrecedenceDfa.
func (d *DFA) getPrecedenceStartState(precedence int) *DFAState {
if !d.getPrecedenceDfa() {
panic("only precedence DFAs may contain a precedence start state")
}
// s0.edges is never nil for a precedence DFA
if precedence < 0 || precedence >= len(d.getS0().getEdges()) {
return nil
}
return d.getS0().getIthEdge(precedence)
}
// setPrecedenceStartState sets the start state for the current precedence. d
// must be a precedence DFA. See also isPrecedenceDfa.
func (d *DFA) setPrecedenceStartState(precedence int, startState *DFAState) {
if !d.getPrecedenceDfa() {
panic("only precedence DFAs may contain a precedence start state")
}
if precedence < 0 {
return
}
// Synchronization on s0 here is ok. When the DFA is turned into a
// precedence DFA, s0 will be initialized once and not updated again. s0.edges
// is never nil for a precedence DFA.
s0 := d.getS0()
if precedence >= s0.numEdges() {
edges := append(s0.getEdges(), make([]*DFAState, precedence+1-s0.numEdges())...)
s0.setEdges(edges)
d.setS0(s0)
}
s0.setIthEdge(precedence, startState)
}
func (d *DFA) getPrecedenceDfa() bool {
return d.precedenceDfa
}
// setPrecedenceDfa sets whether d is a precedence DFA. If precedenceDfa differs
// from the current DFA configuration, then d.states is cleared, the initial
// state s0 is set to a new DFAState with an empty outgoing DFAState.edges to
// store the start states for individual precedence values if precedenceDfa is
// true or nil otherwise, and d.precedenceDfa is updated.
func (d *DFA) setPrecedenceDfa(precedenceDfa bool) {
if d.getPrecedenceDfa() != precedenceDfa {
d.states = NewJStore[*DFAState, *ObjEqComparator[*DFAState]](&ObjEqComparator[*DFAState]{})
d.numstates = 0
if precedenceDfa {
precedenceState := NewDFAState(-1, NewBaseATNConfigSet(false))
precedenceState.setEdges(make([]*DFAState, 0))
precedenceState.isAcceptState = false
precedenceState.requiresFullContext = false
d.setS0(precedenceState)
} else {
d.setS0(nil)
}
d.precedenceDfa = precedenceDfa
}
}
func (d *DFA) getS0() *DFAState {
return d.s0
}
func (d *DFA) setS0(s *DFAState) {
d.s0 = s
}
// sortedStates returns the states in d sorted by their state number.
func (d *DFA) sortedStates() []*DFAState {
vs := d.states.SortedSlice(func(i, j *DFAState) bool {
return i.stateNumber < j.stateNumber
})
return vs
}
func (d *DFA) String(literalNames []string, symbolicNames []string) string {
if d.getS0() == nil {
return ""
}
return NewDFASerializer(d, literalNames, symbolicNames).String()
}
func (d *DFA) ToLexerString() string {
if d.getS0() == nil {
return ""
}
return NewLexerDFASerializer(d).String()
}
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