X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2Fmeta%2FGrammarAST.java;h=05c7b39dc7394dac4cc448b59f5a6dbc70f76422;hp=87f7789269cabbfdc1a2a102567439de866a140a;hb=013262fd96a3dfc4c2cd7a0ba320dd7981ce678c;hpb=67d5def8fede01f412905fb5ff968b79894166fb
diff --git a/src/edu/berkeley/sbp/meta/GrammarAST.java b/src/edu/berkeley/sbp/meta/GrammarAST.java
index 87f7789..05c7b39 100644
--- a/src/edu/berkeley/sbp/meta/GrammarAST.java
+++ b/src/edu/berkeley/sbp/meta/GrammarAST.java
@@ -17,6 +17,14 @@ import java.io.*;
public class GrammarAST {
/**
+ * Returns a Union representing the metagrammar (meta.g); the Tree produced by
+ * parsing with this Union should be provided to buildFromAST
+ */
+ public static Union getMetaGrammar() {
+ return MetaGrammar.newInstance();
+ }
+
+ /**
* Create a grammar from a parse tree and binding resolver
*
* @param t a tree produced by parsing a grammar using the metagrammar
@@ -27,10 +35,6 @@ public class GrammarAST {
return new GrammarAST(includes, "").buildGrammar(grammarAST, startingNonterminal);
}
- public static Union getMetaGrammar() {
- return MetaGrammar.newInstance();
- }
-
private static Object illegalTag = ""; // this is the tag that should never appear in the non-dropped output FIXME
// Instance //////////////////////////////////////////////////////////////////////////////
@@ -88,7 +92,6 @@ public class GrammarAST {
if (head.equals("Elements")) return new Seq((ElementNode[])Reflection.rebuild(walkChildren(t), ElementNode[].class));
if (head.equals("NonTerminalReference")) return new ReferenceNode(stringifyChildren(t.child(0)));
if (head.equals(")")) return new ReferenceNode(stringifyChildren(t.child(0)), true);
- if (head.equals("{")) return new BracedNode(walkSeq(t.child(0)));
if (head.equals("::")) return walkSeq(t.child(1)).tag(walkString(t.child(0)));
if (head.equals("...")) return new DropNode(new RepeatNode(new TildeNode(new AtomNode()), null, true, true, false));
@@ -111,8 +114,8 @@ public class GrammarAST {
if (head.equals("DropNT")) return new NonTerminalNode(walkString(t.child(0)), (Seq[][])walkChildren(t.child(1)), false, null, true);
if (head.equals("=")) return new NonTerminalNode(walkString(t.child(0)), (Seq[][])walk(t.child(2)),
true, t.size()==2 ? null : walkString(t.child(1)), false);
- if (head.equals("&")) return and2(walkSeq(t.child(0)), walkSeq(t.child(1)));
- if (head.equals("&~")) return andnot2(walkSeq(t.child(0)), walkSeq(t.child(1)));
+ if (head.equals("&")) return walkSeq(t.child(0)).and(walkSeq(t.child(1)));
+ if (head.equals("&~")) return walkSeq(t.child(0)).andnot(walkSeq(t.child(1)));
if (head.equals("/")) return (walkSeq(t.child(0))).separate(walkElement(t.child(1)));
if (head.equals("()")) return new LiteralNode("");
if (head.equals("[")) return new AtomNode((char[][])Reflection.rebuild(walkChildren(t), char[][].class));
@@ -204,6 +207,15 @@ public class GrammarAST {
}
}
+ private abstract class ElementNode {
+ public boolean lifted = false;
+ public Seq ownerSeq = null;
+ public ElementNode lifted() { this.lifted = true; return this; }
+ public boolean drop(Context cx) { return false; }
+ public Atom toAtom(Context cx) { throw new Error("can't convert a " + this.getClass().getName() + " to an atom: " + this); }
+ public abstract Element build(Context cx, NonTerminalNode cnt, boolean dropall);
+ }
+
private class UnionNode extends ElementNode {
public Seq[][] sequences;
public String sep = null;
@@ -331,8 +343,8 @@ public class GrammarAST {
}
public Seq tag(String tag) { this.tag = tag; return this; }
public Seq follow(ElementNode follow) { this.follow = follow; return this; }
- public Seq and(Seq s) { and.add(s); return this; }
- public Seq andnot(Seq s) { not.add(s); return this; }
+ public Seq and(Seq s) { and.add(s); s.alwaysDrop = true; return this; }
+ public Seq andnot(Seq s) { not.add(s); s.alwaysDrop = true; return this; }
public Seq separate(ElementNode sep) {
ElementNode[] elements = new ElementNode[this.elements.length * 2 - 1];
for(int i=0; i