X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FParser.java;h=db08afcd22c0afadd2671761384d5a29efcce848;hp=95c3985aa49bb2a65adaf5b4a243de8b6b711d1c;hb=a22c5074e705e3ffcf03e9f9d174aed8ef79fc91;hpb=3eb9fa560dee4f8c3b3af0460ff850d755676d81

diff --git a/src/edu/berkeley/sbp/Parser.java b/src/edu/berkeley/sbp/Parser.java
index 95c3985..db08afc 100644
--- a/src/edu/berkeley/sbp/Parser.java
+++ b/src/edu/berkeley/sbp/Parser.java
@@ -1,28 +1,27 @@
 package edu.berkeley.sbp;
 import edu.berkeley.sbp.*;
 import edu.berkeley.sbp.util.*;
-import edu.berkeley.sbp.*;
 import edu.berkeley.sbp.Sequence.Position;
-import edu.berkeley.sbp.*;
 import java.io.*;
 import java.util.*;
-import java.lang.reflect.*;
 
 /** a parser which translates streams of Tokens of type T into a Forest<R> */
 public abstract class Parser<T extends Token, R> {
 
-    public final Table pt;
+    private final Table pt;
 
     /** create a parser to parse the grammar with start symbol <tt>u</tt> */
     protected Parser(Union u)  { this.pt = new Table(u, top()); }
-    protected Parser(Table pt) { this.pt = pt; }
+    //protected Parser(Table pt) { this.pt = pt; }
 
+    /** implement this method to create the output forest corresponding to a lone shifted input token */
     public abstract Forest<R> shiftedToken(T t, Token.Location loc);
-    public abstract Topology<T> top();
 
+    /** this method must return an empty topology of the input token type */
+    public abstract Topology<T> top();
 
-    /** parse <tt>input</tt> for a exactly one unique result, throwing <tt>Ambiguous</tt> if not unique or <tt>Failed</tt> if none */
-    public Tree<R> parse1(Token.Stream<T> input) throws IOException, Failed, Ambiguous {
+    /** parse <tt>input</tt> for a exactly one unique result, throwing <tt>Ambiguous</tt> if not unique or <tt>ParseFailed</tt> if none */
+    public Tree<R> parse1(Token.Stream<T> input) throws IOException, ParseFailed, Ambiguous {
         Forest<R> ret = parse(input);
         try { return ret.expand1(); }
         catch (Ambiguous a) {
@@ -33,7 +32,7 @@ public abstract class Parser<T extends Token, R> {
     }
 
     /** parse <tt>input</tt>, using the table <tt>pt</tt> to drive the parser */
-    public Forest<R> parse(Token.Stream<T> input) throws IOException, Failed {
+    public Forest<R> parse(Token.Stream<T> input) throws IOException, ParseFailed {
         GSS gss = new GSS();
         Token.Location loc = input.getLocation();
         GSS.Phase current = gss.new Phase(null, this, null, input.next(1, 0, 0), loc, null);
@@ -41,7 +40,6 @@ public abstract class Parser<T extends Token, R> {
         int count = 1;
         for(;;) {
             loc = input.getLocation();
-            //current.checkFailure();
             current.reduce();
             Forest forest = current.token==null ? null : shiftedToken((T)current.token, loc);
             GSS.Phase next = gss.new Phase(current, this, current, input.next(count, gss.resets, gss.waits), loc, forest);
@@ -54,27 +52,6 @@ public abstract class Parser<T extends Token, R> {
 
     // Exceptions //////////////////////////////////////////////////////////////////////////////
 
-    public static class Failed extends RuntimeException {
-        private final Token.Location location;
-        private final String         message;
-        public Failed() { this("", null); }
-        public Failed(String message, Token.Location loc) { this.location = loc; this.message = message; }
-        public Token.Location getLocation() { return location; }
-        public String toString() { return message/* + (location==null ? "" : (" at " + location))*/; }
-    }
-
-    public static class Ambiguous extends RuntimeException {
-        public final Forest ambiguity;
-        public Ambiguous(Forest ambiguity) { this.ambiguity = ambiguity; }
-        public String toString() {
-            StringBuffer sb = new StringBuffer();
-            sb.append("unresolved ambiguity "/*"at " + ambiguity.getLocation() + ":"*/);
-            for(Object result : ambiguity.expand(false))
-                sb.append("\n    " + result);
-            return sb.toString();
-        }
-    }
-
 
     // Table //////////////////////////////////////////////////////////////////////////////
 
@@ -162,10 +139,18 @@ public abstract class Parser<T extends Token, R> {
         }
 
         /** a single state in the LR table and the transitions possible from it */
-        public class State implements Comparable<Table.State>, Iterable<Position>, IntegerMappable {
+
+        public class State implements Comparable<Table.State>, IntegerMappable, Iterable<Position> {
         
             public int toInt() { return idx; }
 
+            public boolean lame() {
+                for(Position p : this)
+                    for(Position p2 = p; p2!=null; p2=p2.next())
+                        if (p2.isLast() && !p2.owner().lame)
+                            return false;
+                return true;
+            }
             /*
             public boolean isResolvable(Token t) {
                 boolean found = false;
@@ -313,7 +298,13 @@ public abstract class Parser<T extends Token, R> {
                 }
             }
 
-            public String toString() { return "state["+idx+"]"; }
+            public String toString() {
+                //return "state["+idx+"]";
+                StringBuffer ret = new StringBuffer();
+                ret.append("state["+idx+"]: ");
+                for(Position p : this) ret.append("{"+p+"}  ");
+                return ret.toString();
+            }
 
             public int compareTo(Table.State s) { return idx==s.idx ? 0 : idx < s.idx ? -1 : 1; }
         }