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Updated documentation for addDFAEdge and addDFAState

This commit is contained in:
Sam Harwell 2013-04-24 11:00:57 -05:00
parent 1a07a6b6fa
commit 297754fff5
1 changed files with 55 additions and 5 deletions
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60
runtime/Java/src/org/antlr/v4/runtime/atn/ParserATNSimulator.java
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@ -1441,25 +1441,75 @@ public class ParserATNSimulator extends ATNSimulator {
return alt;
}
/**
* Add an edge to the DFA, if possible. This method calls
* {@link #addDFAState} to ensure the {@code to} state is present in the
* DFA. If {@code from} is {@code null}, or if {@code t} is outside the
* range of edges that can be represented in the DFA tables, this method
* returns without adding the edge to the DFA.
* <p/>
* If {@code to} is {@code null}, this method returns {@code null}.
* Otherwise, this method returns the {@link DFAState} returned by calling
* {@link #addDFAState} for the {@code to} state.
*
* @param dfa The DFA
* @param from The source state for the edge
* @param t The input symbol
* @param to The target state for the edge
*
* @return If {@code to} is {@code null}, this method returns {@code null};
* otherwise this method returns the result of calling {@link #addDFAState}
* on {@code to}
*/
protected DFAState addDFAEdge(@NotNull DFA dfa,
@Nullable DFAState from,
int t,
@Nullable DFAState to)
{
if ( debug ) System.out.println("EDGE "+from+" -> "+to+" upon "+getTokenName(t));
if ( from==null || t < -1 || to == null ) return to;
if ( debug ) {
System.out.println("EDGE "+from+" -> "+to+" upon "+getTokenName(t));
}
if (to == null) {
return null;
}
to = addDFAState(dfa, to); // used existing if possible not incoming
if (from == null || t < -1 || t > atn.maxTokenType) {
return to;
}
synchronized (from) {
if ( from.edges==null ) {
from.edges = new DFAState[atn.maxTokenType+1+1]; // TODO: make adaptive
from.edges = new DFAState[atn.maxTokenType+1+1];
}
from.edges[t+1] = to; // connect
}
if ( debug ) System.out.println("DFA=\n"+dfa.toString(parser!=null?parser.getTokenNames():null));
if ( debug ) {
System.out.println("DFA=\n"+dfa.toString(parser!=null?parser.getTokenNames():null));
}
return to;
}
/** Add D if not there and return D. Return previous if already present. */
/**
* Add state {@code D} to the DFA if it is not already present, and return
* the actual instance stored in the DFA. If a state equivalent to {@code D}
* is already in the DFA, the existing state is returned. Otherwise this
* method returns {@code D} after adding it to the DFA.
* <p/>
* If {@code D} is {@link #ERROR}, this method returns {@link #ERROR} and
* does not change the DFA.
*
* @param dfa The dfa
* @param D The DFA state to add
* @return The state stored in the DFA. This will be either the existing
* state if {@code D} is already in the DFA, or {@code D} itself if the
* state was not already present.
*/
@NotNull
protected DFAState addDFAState(@NotNull DFA dfa, @NotNull DFAState D) {
if (D == ERROR) {
return D;