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Improve lexer performance during warm-up by tracking DFA states within exec (ATN) and using existing edges when available

This commit is contained in:
Sam Harwell 2012-02-20 19:20:50 -06:00
parent f5edb7653a
commit 5fb389b6e4
1 changed files with 43 additions and 33 deletions
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54
runtime/Java/src/org/antlr/v4/runtime/atn/LexerATNSimulator.java
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@ -201,7 +201,7 @@ public class LexerATNSimulator extends ATNSimulator {
ATNConfigSet s0_closure = computeStartState(input, startState);
int old_mode = mode;
dfa[mode].s0 = addDFAState(s0_closure);
int predict = exec(input, s0_closure);
int predict = exec(input, s0_closure, dfa[mode].s0);
if ( debug ) {
System.out.format("DFA after matchATN: %s\n", dfa[old_mode].toLexerString());
@ -282,7 +282,7 @@ public class LexerATNSimulator extends ATNSimulator {
return dfaPrevAccept.state.prediction;
}
protected int exec(@NotNull CharStream input, @NotNull ATNConfigSet s0) {
protected int exec(@NotNull CharStream input, @NotNull ATNConfigSet s0, @Nullable DFAState ds0) {
//System.out.println("enter exec index "+input.index()+" from "+s0);
@NotNull
ATNConfigSet closure = new ATNConfigSet();
@ -297,12 +297,25 @@ public class LexerATNSimulator extends ATNSimulator {
traceLookahead1();
int t = input.LA(1);
DFAState s = ds0;
while ( true ) { // while more work
if ( debug ) {
System.out.format("in reach starting closure: %s\n", closure);
}
DFAState next = null;
if (s != null) {
if ( s.edges != null && t < s.edges.length && t > CharStream.EOF ) {
closure = s.configset;
next = s.edges[t];
if (next != null) {
reach = next.configset;
}
}
}
if (next == null) {
for (ATNConfig c : closure) {
if ( debug ) {
System.out.format("testing %s at %s\n", getTokenName(t), c.toString(recog, true));
@ -317,12 +330,13 @@ public class LexerATNSimulator extends ATNSimulator {
}
}
}
}
if ( reach.isEmpty() ) {
// we reached state associated with closure for sure, so
// make sure it's defined. worst case, we define s0 from
// start state configs.
DFAState from = addDFAState(closure);
DFAState from = s != null ? s : addDFAState(closure);
// we got nowhere on t, don't throw out this knowledge; it'd
// cause a failover from DFA later.
if (from != null) {
@ -335,17 +349,16 @@ public class LexerATNSimulator extends ATNSimulator {
processAcceptStates(input, reach);
consume(input);
addDFAEdge(closure, t, reach);
if (next == null) {
next = addDFAEdge(s, t, reach);
}
traceLookahead1();
t = input.LA(1);
// swap to avoid reallocating space
// TODO: faster to reallocate?
@NotNull
ATNConfigSet tmp = reach;
reach = closure;
closure = tmp;
reach.clear();
closure = reach;
reach = new ATNConfigSet();
s = next;
}
@ -565,7 +578,7 @@ public class LexerATNSimulator extends ATNSimulator {
input.substring(startIndex, input.index()), s.stateNumber, s.configset);
}
int ttype = exec(input, s.configset);
int ttype = exec(input, s.configset, s);
if ( dfa_debug ) {
System.out.format("back from DFA update, ttype=%d, dfa[mode %d]=\n%s\n",
@ -584,27 +597,24 @@ public class LexerATNSimulator extends ATNSimulator {
state.charPos = charPositionInLine;
}
protected void addDFAEdge(@NotNull ATNConfigSet p,
protected DFAState addDFAEdge(@NotNull DFAState from,
int t,
@NotNull ATNConfigSet q)
{
DFAState to = addDFAState(q);
// even if we can add the states, we can't add an edge for labels out of range
if (t < 0 || t > MAX_DFA_EDGE) {
return;
return to;
}
// 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;
if (from == null || to == null) {
return to;
}
addDFAEdge(from, t, to);
return to;
}
protected void addDFAEdge(@NotNull DFAState p, int t, @NotNull DFAState q) {