X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2Fmisc%2FDemo.java;h=2846d7c841e17ae2fbc59817307c6874c665c66a;hp=2b99ffbe3bf33c5c1ffee506e08aaddc8d42cf04;hb=16460a4ebf976fddbcb4dd79f1fa0b010d61602b;hpb=03e1f20f869819893205ec771571b2c62ab00421

diff --git a/src/edu/berkeley/sbp/misc/Demo.java b/src/edu/berkeley/sbp/misc/Demo.java
index 2b99ffb..2846d7c 100644
--- a/src/edu/berkeley/sbp/misc/Demo.java
+++ b/src/edu/berkeley/sbp/misc/Demo.java
@@ -1,811 +1,58 @@
+// Copyright 2006 all rights reserved; see LICENSE file for BSD-style license
+
 package edu.berkeley.sbp.misc;
-import edu.berkeley.sbp.util.*;
+
 import edu.berkeley.sbp.*;
 import edu.berkeley.sbp.chr.*;
+import edu.berkeley.sbp.misc.*;
+import edu.berkeley.sbp.meta.*;
+import edu.berkeley.sbp.util.*;
 import java.util.*;
-import java.lang.annotation.*;
-import java.lang.reflect.*;
 import java.io.*;
 
 public class Demo {
-    
-    public static boolean harsh = false;
-
-    public static void main(String[] s) throws Exception {
-
-        ReflectiveMeta m = new ReflectiveMeta();
-        Tree<String> res = new CharParser(MetaGrammar.make()).parse(new FileInputStream(s[0])).expand1();
-        MetaGrammar.Meta.MetaGrammarFile mgf = m.new MetaGrammarFile(res);
-        MetaGrammar.BuildContext bc = new MetaGrammar.BuildContext(mgf);
-
-        Union meta = mgf.get("s").build(bc);
-        Tree t = new CharParser(meta).parse(new FileInputStream(s[1])).expand1();
-
-        Union u = Demo.make(t, "s");
-
-        System.err.println();
-        System.err.println("== parsing with parsed grammar =================================================================================");
-        t = new CharParser((Union)u).parse(new FileInputStream(s[1])).expand1();
-        System.out.println(t.toPrettyString());
-
-        System.err.println("== parsing with parsed-parsed grammar ==========================================================================");
-        t = new CharParser(new Context(t, m).build()).parse(new FileInputStream(s[1])).expand1();
-        System.out.println(t.toPrettyString());
-    }
-
-    public static class ReflectiveMetaPlain extends ReflectiveMeta {
-        public Object repeatTag() { return null; }
-        public Sequence tryResolveTag(String tag, String nonTerminalName, Element[] els, Object[] labels, boolean[] drops) {
-            return null; }
-        public Sequence resolveTag(String tag, String nonTerminalName, Element[] els, Object[] labels, boolean[] drops) {
-            return Sequence.rewritingSequence(tag, els, labels, drops);
-        }
-    }
-
-    public static class ReflectiveMeta extends MetaGrammar.Meta {
-        private final Class _cl;
-        private final Class[] _inner;
-        public ReflectiveMeta() {
-            this(MG.class,
-                 new Class[] {
-                     MG.Grammar.class,
-                     MG.NonTerminal.class,
-                     MG.AnonUn.class,
-                     MG.Range.class,
-                     MG.El.class,
-                     MG.Seq.class,
-                     MG.NonTerminalReference.class,
-                     MG.StringLiteral.class,
-                     MG.XTree.class,
-                     MG.CharClass.class
-                 });
-        }
-        public ReflectiveMeta(Class c, Class[] inner) {
-            this._cl = c;
-            this._inner = inner;
-        }
-        private boolean match(Method m, String s) { return match(m.getAnnotation(tag.class), null, s); }
-        private boolean match(tag t, Class c, String s) {
-            if (t==null) return false;
-            if (t.value().equals(s)) return true;
-            if (c != null && t.equals("") && c.getSimpleName().equals(s)) return true;
-            return false;
-        }
-        private boolean match(nonterminal t, Class c, String s) {
-            if (t==null) return false;
-            if (t.value().equals(s)) return true;
-            if (c != null && t.equals("") && c.getSimpleName().equals(s)) return true;
-            return false;
-        }
-        private boolean match(Class c, String s, String nonTerminalName) {
-            if (match((tag)c.getAnnotation(tag.class), c, s)) return true;
-            if (match((nonterminal)c.getAnnotation(nonterminal.class), c, nonTerminalName)) return true;
-            return false;
-        }
-        public boolean match(Constructor con, String s, String nonTerminalName) {
-            Class c = con.getDeclaringClass();
-            if (match((tag)con.getAnnotation(tag.class), null, s)) return true;
-            if (match((nonterminal)con.getAnnotation(nonterminal.class), c, s)) return true;
-            return false;
-        }
-        public Object repeatTag() {
-            return new Reducer() {
-                    public String toString() { return ""; }
-                    public Object reduce(Iterable<Tree> t) {
-                        ArrayList ret = new ArrayList();
-                        for(Tree tc : t) {
-                            if (tc.head() != null && tc.head() instanceof Reducer)
-                                ret.add(((Reducer)tc.head()).reduce(tc.children()));
-                            else if (tc.numChildren() == 0)
-                                ret.add(tc.head());
-                            else {
-                                System.err.println("FIXME: don't know what to do about " + tc);
-                                ret.add(null);
-                            }
-                        }
-                        return ret.toArray(new Object[0]);
-                    }
-                };
-        }
-        public Sequence tryResolveTag(String tag, String nonTerminalName, Element[] els, Object[] labels, boolean[] drops) {
-            Production p = new Production(tag, nonTerminalName, els, labels, drops);
-            for(Method m : _cl.getMethods())
-                if (new TargetMethod(m).isCompatible(p))
-                    return new TargetMethod(m).makeSequence(p);
-            for(Class c : _inner)
-                for(Constructor con : c.getConstructors())
-                    if (new TargetConstructor(con).isCompatible(p))
-                        return new TargetConstructor(con).makeSequence(p);
-            for(Class c : _inner)
-                if (new TargetClass(c).isCompatible(p))
-                    return new TargetClass(c).makeSequence(p);
-            return null;
-        }
-        public Sequence resolveTag(String tag, String nonTerminalName, Element[] els, Object[] labels, boolean[] drops) {
-            Sequence ret = tryResolveTag(tag, nonTerminalName, els, labels, drops);
-            if (ret != null) return ret;
-            String message = "could not find a Java method/class/ctor matching tag \""+tag+
-                "\", nonterminal \""+nonTerminalName+"\" with " + els.length + " arguments";
-            if (harsh) {
-                throw new RuntimeException(message);
-            } else {
-                System.err.println(message);
-                return Sequence.rewritingSequence(tag, els, labels, drops);
-            }
-        }
-    }
-
-    
-    /**
-     *  Constructors, classes, and methods with this attribute will
-     *  match every production of the nonterminal called "value()"
-     *  that is arg-compatible.  If value() is undefined, then the
-     *  class/constructor/method name is used.
-     */ 
-    @Retention(RetentionPolicy.RUNTIME) public static @interface nonterminal { String value() default ""; }
-
-    @Retention(RetentionPolicy.RUNTIME) public static @interface raw { }
-
-    /**
-     *  Constructors, classes, and methods with this attribute will
-     *  match every tree tagged with "value()" that is arg-compatible.
-     *  If value() is undefined, then the class/constructor/method
-     *  name is used.
-     */ 
-    @Retention(RetentionPolicy.RUNTIME) public static @interface tag         { String value() default ""; }
-
-    /**
-     *  If any parameter to a method or field in a class has a named
-     *  arg-tag, that parameter/field matches the child of the tree
-     *  which either has that label or else is a reference to a
-     *  nonterminal with the corresponding name.
-     *  
-     *  The remaining non-named arg-tags match the remaining children
-     *  of the tree in sequential order.
-     *
-     *  If any arg-tagged parameters/fields remain, the match fails.
-     *  If there were no arg-tagged parameters-fields, it is as if all
-     *  of them were non-named and arg-tagged.
-     *
-     *  A method/constructor is arg-compatible if all of its arguments
-     *  are arg-compatible.
-     *
-     *  A class is arg-compatible if all of its fields are
-     *  arg-compatible, or if one of its constructors is arg-compatible.
-     *
-     */
-    @Retention(RetentionPolicy.RUNTIME) public static @interface arg         { String value() default ""; }
-
-    public static class Production {
-        public String tag;
-        public String nonTerminal;
-        public Object[] labels;
-        public boolean[] drops;
-        public Element[] elements;
-        public int count = 0;
-        public Production(String tag, String nonTerminal, Element[] elements, Object[] labels, boolean[] drops) {
-            this.tag = tag;
-            this.elements = elements;
-            this.nonTerminal = nonTerminal;
-            this.labels = labels;
-            this.drops = drops;
-            for(int i=0; i<drops.length; i++)
-                if (!drops[i])
-                    count++;
-        }
-    }
-
-    public static abstract class Target {
-        public abstract String getName();
-        public abstract tag getTag();
-        public abstract nonterminal getNonTerminal();
-        public abstract int[] buildSequence(Production p);
-        public boolean isCompatible(Production p) {
-            tag t = getTag();
-            if (t != null &&
-                (t.value().equals(p.tag) ||
-                 (t.value().equals("") && getName().equals(p.tag))))
-                return buildSequence(p)!=null;
-
-            nonterminal n = getNonTerminal();
-            if (n != null &&
-                (n.value().equals(p.nonTerminal) ||
-                 (n.value().equals("") && getName().equals(p.nonTerminal))))
-                return buildSequence(p)!=null;
-
-            return false;
-        }
-        public int[] buildSequence(Production p, String[] names, arg[] argtags) {
-            int argTagged = 0;
-            for(int i=0; i<argtags.length; i++)
-                if (argtags[i] != null)
-                    argTagged++;
-
-            // FIXME: can be smarter here
-            if (names.length==p.count) {
-                int[] ret = new int[p.count];
-                for(int i=0; i<p.count; i++) ret[i] = i;
-                return ret;
-            } else if (argTagged==p.count) {
-                int[] ret = new int[argtags.length];
-                int j = 0;
-                for(int i=0; i<argtags.length; i++)
-                    ret[i] = argtags[i]==null ? -1 : (j++);
-                return ret;
-            } else {
-                return null;
-            }
-        }
-        public Sequence makeSequence(Production p) {
-            return Sequence.rewritingSequence(new TargetReducer(p, buildSequence(p), "reducer-"+this), p.elements, p.labels, p.drops);
-        }
-        public abstract Object plant(Object[] fields, int[] map);
-        public boolean isRaw() { return false; }
-        public Object invokeRaw(Iterable<Tree> t) { return null; }
-        public class TargetReducer implements Reducer {
-            private Production p;
-            private int[] map;
-            private String name;
-            public TargetReducer(Production p, int[] map, String name) {
-                this.p = p;
-                this.map = map;
-                this.name = name;
-            }
-            public String toString() { return name; }
-            public Object reduce(Iterable<Tree> t) {
-                if (isRaw()) return invokeRaw(t);
-                ArrayList ret = new ArrayList();
-                for(Tree tc : t) {
-                    if (tc.head() != null && tc.head() instanceof Reducer)
-                        ret.add(((Reducer)tc.head()).reduce(tc.children()));
-                    else if (tc.numChildren() == 0)
-                        ret.add(tc.head());
-                    else {
-                        System.err.println("FIXME: don't know what to do about " + tc);
-                        ret.add(null);
-                    }
-                }
-                System.err.println("input tree: " + t);
-                return plant(ret.toArray(new Object[0]), map);
-            }
-        }
-    }
-
-    public static interface Reducer {
-        public Object reduce(Iterable<Tree> t);
-    }
-
-    public static class TargetClass extends Target {
-        public final Class _class;
-        public TargetClass(Class _class) { this._class = _class; }
-        public String getName() { return _class.getSimpleName(); }
-        public tag getTag() { return (tag)_class.getAnnotation(tag.class); }
-        public nonterminal getNonTerminal() { return (nonterminal)_class.getAnnotation(nonterminal.class); }
-        public String toString() { return _class.getSimpleName(); }
-        public int[] buildSequence(Production p) {
-            Field[]  f       = _class.getDeclaredFields();
-            String[] names   = new String[f.length];
-            arg[]    argtags = new arg[f.length];
-            for(int i=0; i<f.length; i++) {
-                names[i]   = f[i].getName();
-                argtags[i] = f[i].getAnnotation(arg.class);
-            }
-            int[] ret = buildSequence(p, names, argtags);
-            if (ret!=null) return ret;
-            for(Constructor c : _class.getConstructors())
-                if (new TargetConstructor(c).buildSequence(p)!=null)
-                    return new TargetConstructor(c).buildSequence(p);
-            return null;
-        }
-        public Object plant(Object[] fields, int[] map) {
-            try {
-                Object ret = _class.newInstance();
-                Field[] f = _class.getFields();
-                int j = 0;
-                for(int i=0; i<f.length; i++)
-                    if (map[i] != -1) {
-                        Object tgt = Reflection.lub(fields[map[i]]);
-                        if (f[i].getType() == String.class) tgt = stringify(tgt);
-                        // FUGLY
-                        tgt = coerce(tgt, f[i].getType());
-                        System.err.println("setting a " + f[i].getType().getName() + " to " + Reflection.show(tgt));
-                        f[i].set(ret, tgt);
-                    }
-                return ret;
-            } catch (Exception e) {
-                e.printStackTrace();
-                throw new RuntimeException(e);
-            }
-        }
-    }
-
-    public static String stringify(Object o) {
-        if (o==null) return "";
-        if (!(o instanceof Object[])) return o.toString();
-        Object[] arr = (Object[])o;
-        StringBuffer ret = new StringBuffer();
-        for(int i=0; i<arr.length; i++)
-            ret.append(arr[i]);
-        return ret.toString();
-    }
+    /*
+    // our grammar class
+    public static class Math {
 
-    public static class TargetConstructor extends Target {
-        public final Constructor _ctor;
-        public TargetConstructor(Constructor _ctor) { this._ctor = _ctor; }
-        public String getName() { return _ctor.getName(); }
-        public tag getTag() { return (tag)_ctor.getAnnotation(tag.class); }
-        public nonterminal getNonTerminal() { return (nonterminal)_ctor.getAnnotation(nonterminal.class); }
-        public String toString() { return _ctor.getName(); }
-        public int[] buildSequence(Production p) {
-            Annotation[][] annotations = _ctor.getParameterAnnotations();
-            int len = annotations.length;
-            int ofs = 0;
-            String name = _ctor.getDeclaringClass().getName();
-            /*
-            if (name.indexOf('$') > name.lastIndexOf('.')) {
-                len--;
-                ofs++;
-            }
-            */
-            String[] names   = new String[len];
-            arg[]    argtags = new arg[len];
-            for(int i=0; i<names.length; i++)
-                for(Annotation a : annotations[i+ofs])
-                    if (a instanceof arg)
-                        argtags[i+ofs] = (arg)a;
-            return buildSequence(p, names, argtags);
-        }
-        public Object plant(Object[] fields, int[] map) {
-            try {
-                Class[] argTypes = _ctor.getParameterTypes();
-                Object[] args = new Object[argTypes.length];
-                int j = 0;
-                for(int i=0; i<args.length; i++)
-                    if (map[i] != -1) {
-                        Object tgt = Reflection.lub(fields[map[i]]);
-                        if (argTypes[i] == String.class) tgt = stringify(tgt);
-                        // FUGLY
-                        tgt = coerce(tgt, argTypes[i]);
-                        System.err.println("setting a " + argTypes[i].getName() + " to " + Reflection.show(tgt));
-                        args[i] = tgt;
-                    }
-                return _ctor.newInstance(args);
-            } catch (Exception e) {
-                throw new RuntimeException(e);
-            }
-        }
-    }
-    public static class TargetMethod extends Target {
-        public final Method _method;
-        public TargetMethod(Method _method) { this._method = _method; }
-        public String getName() { return _method.getName(); }
-        public String toString() { return _method.getName(); }
-        public tag getTag() { return (tag)_method.getAnnotation(tag.class); }
-        public nonterminal getNonTerminal() { return (nonterminal)_method.getAnnotation(nonterminal.class); }
-        public int[] buildSequence(Production p) {
-            Annotation[][] annotations = _method.getParameterAnnotations();
-            String[] names   = new String[annotations.length];
-            arg[]    argtags = new arg[annotations.length];
-            for(int i=0; i<names.length; i++)
-                for(Annotation a : annotations[i])
-                    if (a instanceof arg)
-                        argtags[i] = (arg)a;
-            int[] ret = buildSequence(p, names, argtags);
-            return ret;
-        }
-        public boolean isRaw() { return _method.isAnnotationPresent(raw.class); }
-        public Object invokeRaw(Iterable<Tree> t) {
-            try {
-                return _method.invoke(null, new Object[] { t });
-            } catch (Exception e) {
-                throw new RuntimeException(e);
-            }
-        }
-        public Object plant(Object[] fields, int[] map) {
-            try {
-                Class[] argTypes = _method.getParameterTypes();
-                Object[] args = new Object[argTypes.length];
-                int j = 0;
-                for(int i=0; i<args.length; i++)
-                    if (map[i] != -1) {
-                        Object tgt = Reflection.lub(fields[map[i]]);
-                        if (argTypes[i] == String.class) tgt = stringify(tgt);
-                        // FUGLY
-                        tgt = coerce(tgt, argTypes[i]);
-                        System.err.println("setting a " + argTypes[i].getName() + " to " + Reflection.show(tgt));
-                        args[i] = tgt;
-                    }
-                System.err.println("invoking " + _method + " with " + Reflection.show(args));
-                return _method.invoke(null, args);
-            } catch (Exception e) {
-                throw new RuntimeException(e);
-            }
-        }
-    }
+        public static @bind.as("(") Expr parenthesis(Expr e) { return e; }
+        public static class Expr implements Reflection.Show { }
 
-    public static Object coerce(Object o, Class c) {
-        if (o==null) return null;
-        if (c.isInstance(o)) return o;
-        if (c == char.class) {
-            return o.toString().charAt(0);
+        public static @bind.as("Expr") class Numeric extends Expr {
+            public @bind.arg String numeric;
         }
 
-        if (o.getClass().isArray() &&
-            o.getClass().getComponentType().isArray() &&
-            o.getClass().getComponentType().getComponentType() == String.class &&
-            c.isArray() &&
-            c.getComponentType() == String.class) {
-            String[] ret = new String[((Object[])o).length];
-            for(int i=0; i<ret.length; i++) {
-                StringBuffer sb = new StringBuffer();
-                for(Object ob : (Object[])(((Object[])o)[i]))
-                    sb.append(ob);
-                ret[i] = sb.toString();
-            }
-            return ret;
+        public static class BinOp extends Expr {
+            public @bind.arg Expr left;
+            public @bind.arg Expr right;
         }
 
-        if (c.isArray() && (c.getComponentType().isInstance(o))) {
-            Object[] ret = (Object[])Array.newInstance(c.getComponentType(), 1);
-            ret[0] = o;
-            return ret;
-        }
-
-        if (o.getClass().isArray() && c.isArray()) {
-            boolean ok = true;
-            for(int i=0; i<((Object[])o).length; i++) {
-                Object ob = (((Object[])o)[i]);
-                if (ob != null) {
-                    System.err.println("no hit with " + c.getComponentType().getName() + " on " + Reflection.show(((Object[])o)[i]));
-                    ok = false;
-                }
-            }
-            if (ok) {
-                System.err.println("hit with " + c.getComponentType().getName());
-                return Array.newInstance(c.getComponentType(), ((Object[])o).length);
-            }
-        }
-        return o;
-    }
-
-    public static Union cached = null;
-    public static Union make() {
-        if (cached != null) return cached;
-        try {
-            ReflectiveMeta m = new ReflectiveMeta();
-            Tree<String> res = new CharParser(MetaGrammar.make()).parse(new FileInputStream("tests/meta.g")).expand1();
-            MetaGrammar.Meta.MetaGrammarFile mgf = m.new MetaGrammarFile(res);
-            MetaGrammar.BuildContext bc = new MetaGrammar.BuildContext(mgf);
-            Union meta = mgf.get("s").build(bc);
-            Tree t = new CharParser(meta).parse(new FileInputStream("tests/meta.g")).expand1();
-            return cached = make(t, "s");
-        } catch (Exception e) {
-            throw new RuntimeException(e);
-        }
+        public static @bind.as("*") class Multiply extends BinOp { }
+        public static @bind.as("/") class Divide   extends BinOp { }
+        public static @bind.as("+") class Add      extends BinOp { }
+        public static @bind.as("-") class Subtract extends BinOp { }
     }
-    public static Union make(Tree t, String s) { return make(t, s, new ReflectiveMeta()); }
-    public static Union make(Tree t, String s, ReflectiveMeta rm) {
-        Reducer red = (Reducer)t.head();
-        MG.Grammar g = (MG.Grammar)red.reduce(t.children());
-        Context cx = new Context(g,rm);
-        Union u = null;
-        for(MG.NonTerminal nt : g.nonterminals) {
-            System.out.println(nt.name);
-            Union el = (Union)cx.get(nt.name);
-            StringBuffer st = new StringBuffer();
-            el.toString(st);
-            System.err.println(st);
-            if (nt.name.equals(s)) u = el;
-        }
-        return u;
-    }
-
-    public static class MG {
-        public static @tag("grammar") class Grammar {
-            public NonTerminal get(String s) {
-                for(NonTerminal nt : nonterminals)
-                    if (nt.name.equals(s))
-                        return nt;
-                return null;
-            }
-            public @arg("NonTerminal") NonTerminal[] nonterminals;
-            public String toString() {
-                String ret = "[ ";
-                for(NonTerminal nt : nonterminals) ret += nt + ", ";
-                return ret + " ]";
-            }
-        }
-        public abstract static class Un extends El {
-            public Seq[][] sequences;
-            public void build(Context cx, Union u) {
-                HashSet<Sequence> bad2 = new HashSet<Sequence>();
-                for(int i=0; i<sequences.length; i++) {
-                    Seq[] group = sequences[i];
-                    Union u2 = new Union();
-                    if (sequences.length==1) u2 = u;
-                    for(int j=0; j<group.length; j++) {
-                        group[j].build(cx, u2, false);
-                    }
-                    if (sequences.length==1) break;
-                    Sequence seq = Sequence.singleton(u2);
-                    for(Sequence s : bad2) {
-                        s.lame = true;
-                        seq = seq.not(s);
-                    }
-                    u.add(seq);
-                    bad2.add(Sequence.singleton(u2));
-                }
-            }
-        }
-        public static class NonTerminal extends Un {
-            public String  name = null;
-            public @nonterminal("NonTerminal") NonTerminal(@arg("Word") String name,
-                                                           @arg("RHS") Seq[][] sequences) {
-                this.name = name;
-                this.sequences = sequences;
-            }
-            public Element build(Context cx) { return cx.get(name); }
-        }
-
-        public static class AnonUn extends Un {
-            public @tag("(") AnonUn(Seq[][] sequences) {
-                this.sequences = sequences;
-            }
-            public Element build(Context cx) {
-                Union ret = new Union();
-                build(cx, ret);
-                return ret;
-            }
-        }
-
-        //public static @tag void range(char c) { }
-        public static class Range {
-            public @tag("range") Range(char only) { first = only; last = only; }
-            public @tag("-")     Range(char first, char last) { this.first = first; this.last = last; }
-            public char first;
-            public char last;
-        }
-        public static abstract class El {
-            public String getLabel() { return null; }
-            public String getOwnerTag() { return null; }
-            public boolean drop() { return false; }
-            public abstract Element build(Context cx);
-        }
-        public static class Drop extends El {
-            public El e;
-            public Drop(El e) { this.e = e; }
-            public String getLabel() { return null; }
-            public boolean drop() { return true; }
-            public String getOwnerTag() { return e.getOwnerTag(); }
-            public Element build(Context cx) { return e.build(cx); }
-        }
-        public static class Label extends El {
-            public String label;
-            public El e;
-            public Label(String label, El e) { this.e = e; this.label = label; }
-            public String getLabel() { return label; }
-            public String getOwnerTag() { return e.getOwnerTag(); }
-            public Element build(Context cx) { return e.build(cx); }
-        }
-        public static /*abstract*/ class Seq {
-            HashSet<Seq> and = new HashSet<Seq>();
-            HashSet<Seq> not = new HashSet<Seq>();
-            El[] elements;
-            El follow;
-            String tag = null;
-            boolean lame;
-            public Seq(El e) { this(new El[] { e }); }
-            public Seq(El[] elements) { this.elements = elements; }
-            public Seq tag(String tag) { this.tag = tag; return this; }
-            public Seq follow(El follow) { this.follow = follow; return this; }
-            public Seq dup() {
-                Seq ret = new Seq(elements);
-                ret.and.addAll(and);
-                ret.not.addAll(not);
-                ret.follow = follow;
-                ret.tag = tag;
-                return ret;
-            }
-            public Seq and(Seq s) { and.add(s); s.lame = true; return this; }
-            public Seq andnot(Seq s) { not.add(s); s.lame = true; return this; }
-            public Seq separate(El sep) {
-                El[] elements = new El[this.elements.length * 2 - 1];
-                for(int i=0; i<this.elements.length; i++) {
-                    elements[i*2]   = this.elements[i];
-                    if (i<this.elements.length-1)
-                        elements[i*2+1] = new Drop(sep);
-                }
-                this.elements = elements;
-                return this;
-            }
-            public Sequence build(Context cx, Union u, boolean lame) {
-                Sequence ret = build0(cx, lame || this.lame);
-                for(Seq s : and) { Sequence dork = s.build(cx, u, true); ret = ret.and(dork); }
-                for(Seq s : not) { Sequence dork = s.build(cx, u, true); ret = ret.not(dork); }
-                u.add(ret);
-                ret.lame = lame;
-                return ret;
-            }
-            public Sequence build0(Context cx, boolean lame) {
-                boolean unwrap = false;
-                boolean dropAll = lame;
-                if (tag!=null && tag.equals("[]")) unwrap  = true;
-                if (tag!=null && "()".equals(tag)) dropAll = true;
-                Object[] labels = new Object[elements.length];
-                boolean[] drops = new boolean[elements.length];
-                Element[] els = new Element[elements.length];
-                for(int i=0; i<elements.length; i++) {
-                    labels[i] = elements[i].getLabel();
-                    drops[i]  = elements[i].drop();
-                    els[i] = elements[i].build(cx);
-                    if (elements[i].getOwnerTag() != null)
-                        tag = elements[i].getOwnerTag();
-                }
-                Sequence ret = null;
-                if (dropAll)     ret = Sequence.drop(els, false);
-                else if (unwrap) ret = Sequence.unwrap(els, cx.rm.repeatTag(), drops);
-                else if (tag!=null) {
-                    ret = cx.rm.resolveTag(tag, cx.cnt, els, labels, drops);
-                } else {
-                    int idx = -1;
-                    for(int i=0; i<els.length; i++)
-                        if (!drops[i])
-                            if (idx==-1) idx = i;
-                            else throw new Error("multiple non-dropped elements in sequence: " + Sequence.drop(els,false));
-                    if (idx != -1) ret = Sequence.singleton(els, idx);
-                    else           ret = Sequence.drop(els, false);
-                }
-                if (this.follow != null)
-                    ret.follow = MetaGrammar.infer(this.follow.build(cx));
-                ret.lame = this.lame;
-                return ret;
-            }
-        }
-        public static @tag("&")   Seq  and(Seq s,         El[] elements) { return s.and(seq(elements)); }
-        public static @tag("&~")  Seq  andnot(Seq s,      El[] elements) { return s.andnot(seq(elements)); }
-        public static @tag("->")  Seq  arrow(Seq s, El e)                { return s.follow(e); }
-        public static @tag("::")  Seq  tag(String tagname, Seq s)        { return s.tag(tagname); }
-        public static @tag("/")   Seq  slash(Seq s, El e)                { return s.separate(e); }
 
-        public static @tag("ps")  Seq  seq(El[] elements)                { return new Seq(elements); }
-        public static @tag        Seq  psx(Seq s)                        { return s; }
-        public static @tag(":")   El   colon(String s, El e)             { return new Label(s, e); }
-        public static @tag(")")   void close(String foo)                 { throw new Error("not supported"); }
-        public static @tag("()")  El   epsilon()                         { return new Constant(Union.epsilon); }
-
-        public static @tag("nonTerminal") class NonTerminalReference extends El {
-            public @arg String nonTerminal;
-            public Element build(Context cx) {
-                return cx.get(nonTerminal);
-            }
-        }
 
-        public static class StringLiteral        extends Constant {
-            public @tag("literal") StringLiteral(String string) { super(CharRange.string(string)); }
-            public boolean drop() { return true; }
-        }
-
-        public static                     class CharClass            extends El {
-            Range[] ranges;
-            public @tag("[") CharClass(Range[] ranges) { this.ranges = ranges; }
-            public Element build(Context cx) {
-                edu.berkeley.sbp.util.Range.Set set = new edu.berkeley.sbp.util.Range.Set();
-                for(Range r : ranges)
-                        set.add(r.first, r.last);
-                return CharRange.set(set);
-            }
-        }
-
-        public static @tag("{")           class XTree                 extends El {
-            public @arg Seq body;
-            public Element build(Context cx) {
-                throw new Error();
-            }
-        }
-
-        public static class Rep extends El {
-            public El e, sep;
-            public boolean zero, many, max;
-            public Rep(El e, El sep, boolean zero, boolean many, boolean max) {
-                this.e = e; this.sep = sep; this.zero = zero; this.many = many; this.max = max;}
-            public Element build(Context cx) {
-                return (!max)
-                    ? Sequence.repeat(e.build(cx),        zero, many, sep==null ? null : sep.build(cx), cx.rm.repeatTag())
-                    : sep==null
-                    ? Sequence.repeatMaximal(MetaGrammar.infer(e.build(cx)), zero, many,                                   cx.rm.repeatTag())
-                    : Sequence.repeatMaximal(e.build(cx),                    zero, many, MetaGrammar.infer(sep.build(cx)), cx.rm.repeatTag());
-            }
-        }
-        public static class Constant extends El {
-            Element constant;
-            public Constant(Element constant) { this.constant = constant; }
-            public Element build(Context cx) { return constant; }
-        }
-        public abstract static class PostProcess extends El {
-            El e;
-            public PostProcess(El e) { this.e = e; }
-            public Element build(Context cx) { return postProcess(e.build(cx)); }
-            public abstract Element postProcess(Element e);
-        }
-
-        // FIXME: it would be nice if we could hoist this into "Rep"
-        public static @tag("++")  El plusmax(final El e)                     { return new Rep(e, null, false, true, true); }
-        public static @tag("+")   El plus(final El e)                        { return new Rep(e, null, false, true, false); }
-        public static @tag("++/") El plusmaxfollow(final El e, final El sep) { return new Rep(e, sep,  false, true, true); }
-        public static @tag("+/")  El plusfollow(final El e, final El sep)    { return new Rep(e, sep,  false, true, false); }
-        public static @tag("**")  El starmax(final El e)                     { return new Rep(e, null, true,  true, true); }
-        public static @tag("*")   El star(final El e)                        { return new Rep(e, null, true,  true, false); }
-        public static @tag("**/") El starmaxfollow(final El e, final El sep) { return new Rep(e, sep,  true,  true, true); }
-        public static @tag("*/")  El starfollow(final El e, final El sep)    { return new Rep(e, sep,  true,  true, false); }
-        public static @tag("?")   El question(final El e)                    { return new Rep(e, null, true,  true, false); }
-
-        public static @tag("!")   El bang(final El e)                        { return new Drop(e); }
-
-        public static @tag("^")   El caret(final String s) {
-            return new Drop(new Constant(CharRange.string(s)) {
-                    public String getOwnerTag() { return s; }
-                });
-        }
-
-        public static @tag("~")   El tilde(final El e) {
-            return new PostProcess(e) {
-                    public Element postProcess(Element e) {
-                        return MetaGrammar.infer((Topology<Character>)Atom.toAtom(e).complement()); 
-                    } }; }
-
-        public static @tag("^^")  void doublecaret(final El e)                 { throw new Error("not implemented"); }
+    // invoke "java -jar edu.berkeley.sbp.jar edu.berkeley.sbp.misc.Demo tests/demo.g <expr>"
+    public static void main(String[] s) throws Exception {
 
-        //public static @tag("(")   El subexpression(Seq[][] rhs)                { return new NonTerminal(rhs); }
+        Parser metaGrammarParser   = new CharParser(MetaGrammar.newInstance());
+        Tree<String> parsedGrammar = metaGrammarParser.parse(new CharInput(new FileInputStream(s[0]))).expand1();
+        Grammar.Bindings gbr       = new AnnotationGrammarBindings(Math.class);
+        Union   mathGrammar        = Grammar.create(parsedGrammar, "Expr", gbr);
+        Parser  mathParser         = new CharParser(mathGrammar);
 
-        public static @nonterminal("Word")    String word(String s) { return s; }
-        public static @nonterminal("Quoted")  String quoted(String s) { return s; }
-        public static @nonterminal("escaped") String c(char c) { return c+""; }
-        public static @tag("\"\"")            String emptystring() { return ""; }
-        public static @tag("\n")              String retur() { return "\n"; }
-        public static @tag("\r")              String lf() { return "\r"; }
+        System.out.println("about to parse: \""+s[1]+"\"");
+        Tree tree = mathParser.parse(new CharInput(new StringReader(s[1]))).expand1();
 
-    }
-    public static class Context {
-        HashMap<String,Union> map = new HashMap<String,Union>();
-        private MG.Grammar grammar;
-        public String cnt = null;
-        private ReflectiveMeta rm;
-        public Context(MG.Grammar g, ReflectiveMeta rm) {
-            this.grammar = g;
-            this.rm = rm;
-        }
-        public Union build() {
-            Union ret = null;
-            for(MG.NonTerminal nt : grammar.nonterminals) {
-                Union u = get(nt.name);
-                if ("s".equals(nt.name))
-                    ret = u;
-            }
-            return ret;
-        }
-        public Context(Tree t, ReflectiveMeta rm) {
-            this.rm = rm;
-            Reducer red = (Reducer)t.head();
-            this.grammar = (MG.Grammar)red.reduce(t.children());
-        }
-        public Union peek(String name) { return map.get(name); }
-        public void  put(String name, Union u) { map.put(name, u); }
-        public Union get(String name) {
-            Union ret = map.get(name);
-            if (ret != null) return ret;
-            ret = new Union(name);
-            map.put(name, ret);
-            MG.NonTerminal nt = grammar.get(name);
-            if (nt==null) {
-                System.err.println("*** warning could not find " + name);
-            } else {
-                String old = cnt;
-                cnt = name;
-                nt.build(this, ret);
-                cnt = old;
-            }
-            return ret;
-        }
+        // below is ugly voodoo which will go away very soon.  ignore it.
+        TreeFunctor tf = (TreeFunctor)tree.head();
+        Math.Expr e = (Math.Expr)tf.invoke(tree);
+        // above is ugly voodoo which will go away very soon.  ignore it.
 
+        System.out.println("done!");
+        System.out.println(Reflection.show(e));
     }
+    */
 }