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// 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
import (
"sort"
"sync"
)
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.
states map[int]*DFAState
statesMu sync.RWMutex
s0 *DFAState
s0Mu sync.RWMutex
// 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 {
return &DFA{
atnStartState: atnStartState,
decision: decision,
states: make(map[int]*DFAState),
}
}
// 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.precedenceDfa {
panic("only precedence DFAs may contain a precedence start state")
}
d.s0Mu.RLock()
defer d.s0Mu.RUnlock()
// s0.edges is never nil for a precedence DFA
if precedence < 0 || precedence >= len(d.s0.edges) {
return nil
}
return d.s0.edges[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.precedenceDfa {
panic("only precedence DFAs may contain a precedence start state")
}
if precedence < 0 {
return
}
d.s0Mu.Lock()
defer d.s0Mu.Unlock()
// 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.
if precedence >= len(d.s0.edges) {
d.s0.edges = append(d.s0.edges, make([]*DFAState, precedence+1-len(d.s0.edges))...)
}
d.s0.edges[precedence] = startState
}
// 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.precedenceDfa != precedenceDfa {
d.states = make(map[int]*DFAState)
if precedenceDfa {
precedenceState := NewDFAState(-1, NewBaseATNConfigSet(false))
precedenceState.edges = make([]*DFAState, 0)
precedenceState.isAcceptState = false
precedenceState.requiresFullContext = false
d.s0 = precedenceState
} else {
d.s0 = nil
}
d.precedenceDfa = precedenceDfa
}
}
func (d *DFA) getS0() *DFAState {
d.s0Mu.RLock()
defer d.s0Mu.RUnlock()
return d.s0
}
func (d *DFA) setS0(s *DFAState) {
d.s0Mu.Lock()
defer d.s0Mu.Unlock()
d.s0 = s
}
func (d *DFA) getState(hash int) (*DFAState, bool) {
d.statesMu.RLock()
defer d.statesMu.RUnlock()
s, ok := d.states[hash]
return s, ok
}
func (d *DFA) setState(hash int, state *DFAState) {
d.statesMu.Lock()
defer d.statesMu.Unlock()
d.states[hash] = state
}
func (d *DFA) numStates() int {
d.statesMu.RLock()
defer d.statesMu.RUnlock()
return len(d.states)
}
type dfaStateList []*DFAState
func (d dfaStateList) Len() int { return len(d) }
func (d dfaStateList) Less(i, j int) bool { return d[i].stateNumber < d[j].stateNumber }
func (d dfaStateList) Swap(i, j int) { d[i], d[j] = d[j], d[i] }
// sortedStates returns the states in d sorted by their state number.
func (d *DFA) sortedStates() []*DFAState {
vs := make([]*DFAState, 0, len(d.states))
for _, v := range d.states {
vs = append(vs, v)
}
sort.Sort(dfaStateList(vs))
return vs
}
func (d *DFA) String(literalNames []string, symbolicNames []string) string {
if d.s0 == nil {
return ""
}
return NewDFASerializer(d, literalNames, symbolicNames).String()
}
func (d *DFA) ToLexerString() string {
if d.s0 == nil {
return ""
}
return NewLexerDFASerializer(d).String()
}
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