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) {
}
/** 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);
// 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 //////////////////////////////////////////////////////////////////////////////