X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FInput.java;h=bf0d50deb2e02f14ec73b0e88d1f9e1f6d0b3604;hp=846fd9a7b60de45439cc7650913e8121e6f1c75a;hb=449c39e0dafd7c736bfcd8d56bbd08b7a99e25a4;hpb=e12a3098c6ed3cbfa6493870af3688f833c4f8ac

diff --git a/src/edu/berkeley/sbp/Input.java b/src/edu/berkeley/sbp/Input.java
index 846fd9a..bf0d50d 100644
--- a/src/edu/berkeley/sbp/Input.java
+++ b/src/edu/berkeley/sbp/Input.java
@@ -1,3 +1,5 @@
+// Copyright 2006 all rights reserved; see LICENSE file for BSD-style license
+
 package edu.berkeley.sbp;
 import java.io.*;
 import java.util.*;
@@ -6,7 +8,7 @@ import java.lang.ref.*;
 import edu.berkeley.sbp.*;
 import edu.berkeley.sbp.util.*;
 
-/** a stream of tokens to be parsed */
+/** <font color=purple>a stream of <tt>Token</tt>s to be parsed</font> */
 public interface Input<Token> {
 
     /** returns the token just beyond the current location and advances beyond it */
@@ -14,24 +16,52 @@ public interface Input<Token> {
 
     /** returns the location the input stream is currently at */
     public Location<Token> getLocation();
+    
+    /** should return a short string describing where the input is coming from */
+    public String getName();
+
+    /**
+     *  <b>Optional:</b> <i>If possible</i>, this method will return a
+     *  rendering of the input region (for example, if the input is a
+     *  region of characters, it would be those characters) --
+     *  otherwise, returns null.  In any case, the string returned
+     *  will be no more than <tt>maxLength</tt> characters long;
+     *  typically ellipses will be inserted to perform truncation.
+     */
+    public abstract String showRegion(Region<Token> r, int maxLength);
+
+    /** <font color=purple>a location (position) in the input stream -- <i>between tokens</i></font> */
+    public static interface Location<Token> extends Comparable<Location> {
+
+        /** return the region between this location and <tt>loc</tt> */
+        public Region<Token> createRegion(Location<Token> loc);
 
-    /** a location <i>between tokens<i> in the input stream */
-    public static interface Location<Tok> extends Comparable<Location> {
         public String toString();
+
+        /** the location following this one */
+        public Location next();
+
+        /** the location preceding this one */
+        public Location prev();
     }
 
-    public static class Region<Loc extends Location> /* implements Topology<Location<Tok>> */ {
-        public final Loc start;
-        public final Loc end;
-        public Region(Loc a, Loc b) {
-            switch(a.compareTo(b)) {
-                case -1:
-                case  0: start=a; end=b; return;
-                case  1: start=b; end=a; return;
-                default: throw new Error("impossible");
-            }
-        }
+    /** <font color=purple>a contiguous set of <tt>Location</tt>s</font> */
+    public static interface Region<Token> /* implements Topology<Location<Tok>> */ {
+
+        /**
+         *  the toString() method of Region should return a <80char
+         *  "rendition" of the input region, if possible
+         */
+        public abstract String toString();
+        
+        /** The location of the start of this region */
+        public abstract Location<Token> getStart();
+
+        /** The location of the end of this region */
+        public abstract Location<Token> getEnd();
+
     }
+
 }