From 013262fd96a3dfc4c2cd7a0ba320dd7981ce678c Mon Sep 17 00:00:00 2001
From: adam <adam@megacz.com>
Date: Sun, 27 May 2007 19:27:30 -0400
Subject: [PATCH] GrammarAST: remove BracedNode, refactor, remove
 getOwnerTag()

darcs-hash:20070527232730-5007d-275023fb0288c1072a36486d8e10c85b1cc18236.gz
---
 src/edu/berkeley/sbp/meta/GrammarAST.java |   73 ++++++++++-------------------
 1 file changed, 26 insertions(+), 47 deletions(-)

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 (<tt>meta.g</tt>); the Tree produced by
+     *  parsing with this Union should be provided to <tt>buildFromAST</tt>
+     */
+    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<this.elements.length; i++) {
@@ -357,8 +369,10 @@ public class GrammarAST {
             for(int i=0; i<elements.length; i++) {
                 if (dropall) drops[i] = true;
                 else         drops[i] = elements[i].drop(cx);
-                if (elements[i].getOwnerTag() != null)
-                    tag = elements[i].getOwnerTag();
+                if (elements[i] instanceof LiteralNode && ((LiteralNode)elements[i]).caret) {
+                    if (tag != null) throw new RuntimeException("cannot have multiple tags in a sequence: " + this);
+                    tag = ((LiteralNode)elements[i]).getLiteralTag();
+                }
             }
             Sequence ret = null;
             int idx = -1;
@@ -416,10 +430,6 @@ public class GrammarAST {
         }
         public boolean drop(Context cx) { return resolve(cx).drop(cx); }
         public Element build(Context cx, NonTerminalNode cnt, boolean dropall) {
-            /*
-            if (!this.nonTerminal.startsWith(prefix))
-                nonTerminal = prefix + nonTerminal;
-            */
             Element ret = cx.get(nonTerminal);
             if (ret == null) throw new RuntimeException("unknown nonterminal \""+nonTerminal+"\"");
             return ret;
@@ -435,7 +445,7 @@ public class GrammarAST {
             this.string = string;
             this.caret = caret;
         }
-        public String getOwnerTag() { return caret ? thePrefix+string : super.getOwnerTag(); }
+        public String getLiteralTag() { return caret ? thePrefix+string : null; }
         public String toString() { return "\""+string+"\""; }
         public boolean drop(Context cx) { return true; }
         public Atom toAtom(Context cx) {
@@ -486,20 +496,9 @@ public class GrammarAST {
         }
     }
 
-    private abstract class ElementNode {
-        public boolean lifted = false;
-        public Seq ownerSeq = null;
-        public String getOwnerTag() { return 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 abstract class ElementNodeWrapper extends ElementNode {
         protected ElementNode _e;
         public ElementNodeWrapper(ElementNode e) { this._e = e; }
-        public String getOwnerTag() { return _e.getOwnerTag(); }
         public boolean drop(Context cx) { return _e.drop(cx); }
         public Atom toAtom(Context cx) { return _e.toAtom(cx); }
         public Element build(Context cx, NonTerminalNode cnt, boolean dropall) { return _e.build(cx, cnt, dropall); }
@@ -516,26 +515,6 @@ public class GrammarAST {
         public boolean drop(Context cx) { return true; }
     }
 
-    // FIXME: doesn't this require a tag?
-    private class BracedNode extends ElementNode {
-        public Seq body;
-        public BracedNode(Seq seq) { this.body = seq; }
-        public Element build(Context cx, NonTerminalNode cnt, boolean dropall) {
-            Union u = new Union(null, false);
-            Sequence s = body.build(cx, u, null, dropall);
-            Union u2 = new Union(null, false);
-            u2.add(Sequence.create(new Element[] {
-                CharAtom.leftBrace,
-                u,
-                CharAtom.rightBrace
-            }, 1));
-            return u2;
-        }
-    }
-
-    public Seq  and2(Seq s,    Seq a) { a.alwaysDrop = true; return s.and(a);    }
-    public Seq  andnot2(Seq s, Seq a) { a.alwaysDrop = true; return s.andnot(a); }
-
     //////////////////////////////////////////////////////////////////////////////
 
     public class Context {
-- 
1.7.10.4