X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FElement.java;h=0d7fb84f583ea0ba9594a9b23cf88d83998afafc;hb=f8dec42308b5eb1196db5bf56bb2f5426b4a76af;hp=b4402574b9220781633d35a0dd0e66d1c97bf195;hpb=0516ea34996c86664928ef948013b749876b87ec;p=sbp.git diff --git a/src/edu/berkeley/sbp/Element.java b/src/edu/berkeley/sbp/Element.java index b440257..0d7fb84 100644 --- a/src/edu/berkeley/sbp/Element.java +++ b/src/edu/berkeley/sbp/Element.java @@ -10,17 +10,9 @@ import java.lang.ref.*; /** the root superclass for all components of the grammar (terminals, nonterminals, literals, etc) */ public abstract class Element { - /** add all positions reachable from the start of this Element to @rp */ - abstract void reachable(HashSet rp); + abstract StringBuffer toString(StringBuffer sb); + + /** returns the Forest resulting from matching this element against the empty string */ + Forest epsilonForm() { throw new Error("element " + this + " has no epsilon form"); } - abstract Topology toAtom(); - public Topology noFollow() { return null; } - Forest epsilonForm() { throw new Error("no epsilon form: " + this); } - final boolean possiblyEpsilon(Walk.Cache cache) { - Boolean ret = cache==null ? null : cache.possiblyEpsilon.get(this); - if (ret != null) return ret.booleanValue(); - ret = new Walk.PossiblyEpsilon().walk(this) ? Boolean.TRUE : Boolean.FALSE; - if (cache != null) cache.possiblyEpsilon.put(this, ret); - return ret; - } }