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v4: Check for early return conditions during DFA updates 

[git-p4: depot-paths = "//depot/code/antlr4/main/": change = 9494]
This commit is contained in:
sharwell 2011-11-30 07:05:38 -08:00
parent 83a5f592d0
commit 8096b3b4c4
1 changed files with 18 additions and 4 deletions
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22
runtime/Java/src/org/antlr/v4/runtime/atn/LexerATNSimulator.java
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@ -287,7 +287,9 @@ public class LexerATNSimulator extends ATNSimulator {
DFAState from = addDFAState(closure);
// we got nowhere on t, don't throw out this knowledge; it'd
// cause a failover from DFA later.
addDFAEdge(from, t, ERROR);
if (from != null) {
addDFAEdge(from, t, ERROR);
}
break;
}
@ -535,15 +537,27 @@ public class LexerATNSimulator extends ATNSimulator {
int t,
@NotNull OrderedHashSet<ATNConfig> q)
{
// even if we can add the states, we can't add an edge for labels out of range
if (t < 0 || t > NUM_EDGES) {
return;
}
// System.out.println("MOVE "+p+" -> "+q+" upon "+getTokenName(t));
DFAState from = addDFAState(p);
if (from == null) {
return;
}
DFAState to = addDFAState(q);
if (to == null) {
return;
}
addDFAEdge(from, t, to);
}
// TODO (sam): should we allow q==null?
protected void addDFAEdge(@Nullable DFAState p, int t, DFAState q) {
if ( p==null || t==CharStream.EOF || q==null ) return; // Don't track EOF edges from stop states
protected void addDFAEdge(@NotNull DFAState p, int t, @NotNull DFAState q) {
if (t < 0 || t > NUM_EDGES) return; // Only track edges within the DFA bounds
if ( p.edges==null ) {
// make room for tokens 1..n and -1 masquerading as index 0
p.edges = new DFAState[NUM_EDGES+1]; // TODO: make adaptive