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Updated documentation in LL1Analyzer

This commit is contained in:
Sam Harwell 2013-05-14 16:26:45 -05:00
parent 1906e4a639
commit f9f4883855
1 changed files with 51 additions and 17 deletions
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68
runtime/Java/src/org/antlr/v4/runtime/atn/LL1Analyzer.java
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@ -30,7 +30,6 @@
package org.antlr.v4.runtime.atn;
import org.antlr.v4.runtime.IntStream;
import org.antlr.v4.runtime.RuleContext;
import org.antlr.v4.runtime.Token;
import org.antlr.v4.runtime.misc.IntervalSet;
@ -43,7 +42,7 @@ import java.util.Set;
public class LL1Analyzer {
/** Special value added to the lookahead sets to indicate that we hit
* a predicate during analysis if seeThruPreds==false.
* a predicate during analysis if {@code seeThruPreds==false}.
*/
public static final int HIT_PRED = Token.INVALID_TYPE;
@ -53,8 +52,14 @@ public class LL1Analyzer {
public LL1Analyzer(@NotNull ATN atn) { this.atn = atn; }
/**
* From an ATN state, {@code s}, find the set of all labels reachable from
* {@code s} at depth k. Only for DecisionStates.
* Calculates the SLL(1) expected lookahead set for each outgoing transition
* of an {@link ATNState}. The returned array has one element for each
* outgoing transition in {@code s}. If the closure from transition
* <em>i</em> leads to a semantic predicate before matching a symbol, the
* element at index <em>i</em> of the result will be {@code null}.
*
* @param s the ATN state
* @return the expected symbols for each outgoing transition of {@code s}.
*/
@Nullable
public IntervalSet[] getDecisionLookahead(@Nullable ATNState s) {
@ -81,12 +86,20 @@ public class LL1Analyzer {
}
/**
* Get lookahead, using {@code ctx} if we reach end of rule. If {@code ctx}
* is {@code null} or {@link RuleContext#EMPTY EMPTY}, don't chase FOLLOW.
* If {@code ctx} is {@code null}, {@link Token#EPSILON EPSILON} is in set
* if we can reach end of rule. If {@code ctx} is
* {@link RuleContext#EMPTY EMPTY}, {@link IntStream#EOF EOF} is in set if
* we can reach end of rule.
* Compute set of tokens that can follow {@code s} in the ATN in the
* specified {@code ctx}.
* <p/>
* If {@code ctx} is {@code null} and the end of the rule containing
* {@code s} is reached, {@link Token#EPSILON} is added to the result set.
* If {@code ctx} is not {@code null} and the end of the outermost rule is
* reached, {@link Token#EOF} is added to the result set.
*
* @param s the ATN state
* @param ctx the complete parser context, or {@code null} if the context
* should be ignored
*
* @return The set of tokens that can follow {@code s} in the ATN in the
* specified {@code ctx}.
*/
@NotNull
public IntervalSet LOOK(@NotNull ATNState s, @Nullable RuleContext ctx) {
@ -98,13 +111,34 @@ public class LL1Analyzer {
return r;
}
/** Compute set of tokens that can come next. If the {@code ctx} is {@link PredictionContext#EMPTY},
* then we don't go anywhere when we hit the end of the rule. We have
* the correct set. If {@code ctx} is null, that means that we did not want
* any tokens following this rule--just the tokens that could be found within this
* rule. Add {@link Token#EPSILON} to the set indicating we reached the end of the ruled out having
* to match a token.
*/
/**
* Compute set of tokens that can follow {@code s} in the ATN in the
* specified {@code ctx}.
* <p/>
* If {@code ctx} is {@code null} and the end of the rule containing
* {@code s} is reached, {@link Token#EPSILON} is added to the result set.
* If {@code ctx} is not {@code null} and {@code addEOF} is {@code true} and
* the end of the outermost rule is reached, {@link Token#EOF} is added to
* the result set.
*
* @param s the ATN state.
* @param ctx The outer context, or {@code null} if the outer context should
* not be used.
* @param look The result lookahead set.
* @param lookBusy A set used for preventing epsilon closures in the ATN
* from causing a stack overflow. Outside code should pass
* {@code new HashSet<ATNConfig>} for this argument.
* @param calledRuleStack A set used for preventing left recursion in the
* ATN from causing a stack overflow. Outside code should pass
* {@code new BitSet()} for this argument.
* @param seeThruPreds {@code true} to true semantic predicates as
* implicitly {@code true} and "see through them", otherwise {@code false}
* to treat semantic predicates as opaque and add {@link #HIT_PRED} to the
* result if one is encountered.
* @param addEOF Add {@link Token#EOF} to the result if the end of the
* outermost context is reached. This parameter has no effect if {@code ctx}
* is {@code null}.
*/
protected void _LOOK(@NotNull ATNState s, @Nullable PredictionContext ctx,
@NotNull IntervalSet look,
@NotNull Set<ATNConfig> lookBusy,