From e1362fdb833381c44b5a432285be1582d36d2e33 Mon Sep 17 00:00:00 2001
From: "kr.angelov" <kr.angelov@gmail.com>
Date: Wed, 28 Aug 2013 08:51:53 +0000
Subject: [PATCH] fix the error handling in the Java binding

---
 src/runtime/java/Test.java                    | 20 ++++++++++++-------
 src/runtime/java/jpgf.c                       |  1 +
 .../org/grammaticalframework/pgf/Concr.java   |  4 ++--
 .../org/grammaticalframework/pgf/Expr.java    |  2 +-
 .../grammaticalframework/pgf/ParseError.java  | 11 ++++++++++
 .../org/grammaticalframework/pgf/Parser.java  | 20 ++++++++++++++-----
 6 files changed, 43 insertions(+), 15 deletions(-)
 create mode 100644 src/runtime/java/org/grammaticalframework/pgf/ParseError.java

diff --git a/src/runtime/java/Test.java b/src/runtime/java/Test.java
index c4d7b710c..15a8ff7ff 100644
--- a/src/runtime/java/Test.java
+++ b/src/runtime/java/Test.java
@@ -6,7 +6,7 @@ public class Test {
 	public static void main(String[] args) {
 		PGF gr = null;
 		try {
-			gr = PGF.readPGF("/home/krasimir/www.grammaticalframework.org/treebanks/PennTreebank/ParseEngAbs.pgf");
+			gr = PGF.readPGF("Phrasebook.pgf");
 		} catch (FileNotFoundException e) {
 			e.printStackTrace();
 			return;
@@ -14,16 +14,22 @@ public class Test {
 			e.printStackTrace();
 			return;
 		}
-		
+
 		System.out.println(gr.getAbstractName());
 		for (Map.Entry<String,Concr> entry : gr.getLanguages().entrySet()) {
 			System.out.println(entry.getKey()+" "+entry.getValue()+" "+entry.getValue().getName());
 		}
-		
-		Concr eng = gr.getLanguages().get("ParseEng");
-		for (ExprProb ep : eng.parse("Phr", "where are you")) {
-			System.out.println("["+ep.getProb()+"] "+ep.getExpr());
-			System.out.println(eng.linearize(ep.getExpr()));
+
+		Concr eng = gr.getLanguages().get("PhrasebookEng");
+		Concr ger = gr.getLanguages().get("PhrasebookGer");
+
+		try {
+			for (ExprProb ep : eng.parse(gr.getStartCat(), "where is the conference")) {
+				System.out.println("["+ep.getProb()+"] "+ep.getExpr());
+				System.out.println(ger.linearize(ep.getExpr()));
+			}
+		} catch (ParseError e) {
+			System.out.println("Parsing failed at token \""+e.getToken()+"\"");
 		}
 	}
 }
diff --git a/src/runtime/java/jpgf.c b/src/runtime/java/jpgf.c
index f04f32e24..ec68c87a4 100644
--- a/src/runtime/java/jpgf.c
+++ b/src/runtime/java/jpgf.c
@@ -226,6 +226,7 @@ Java_org_grammaticalframework_pgf_Parser_parse
 
 		gu_pool_free(pool);
 		gu_pool_free(out_pool);
+		return NULL;
 	}
 
 	jclass expiter_class = (*env)->FindClass(env, "org/grammaticalframework/pgf/ExprIterator");
diff --git a/src/runtime/java/org/grammaticalframework/pgf/Concr.java b/src/runtime/java/org/grammaticalframework/pgf/Concr.java
index df4d1c54f..6fde4c63f 100644
--- a/src/runtime/java/org/grammaticalframework/pgf/Concr.java
+++ b/src/runtime/java/org/grammaticalframework/pgf/Concr.java
@@ -6,7 +6,7 @@ public class Concr {
 
 	public native String getName();
 
-	public Iterable<ExprProb> parse(String startCat, String s) {
+	public Iterable<ExprProb> parse(String startCat, String s) throws ParseError {
 		return new Parser(this, startCat, s);
 	}
 
@@ -25,7 +25,7 @@ public class Concr {
 	// private stuff
 	
 	private PGF gr;
-	public long ref;
+	private long ref;
 
 	private Concr(PGF gr, long ref) {
 		this.gr  = gr;
diff --git a/src/runtime/java/org/grammaticalframework/pgf/Expr.java b/src/runtime/java/org/grammaticalframework/pgf/Expr.java
index e129af68d..0dc4d1c4b 100644
--- a/src/runtime/java/org/grammaticalframework/pgf/Expr.java
+++ b/src/runtime/java/org/grammaticalframework/pgf/Expr.java
@@ -4,7 +4,7 @@ public class Expr {
 		private Pool pool;
 		private long ref;
 
-		private Expr(Pool pool, long ref) {
+		Expr(Pool pool, long ref) {
 			this.pool = pool;
 			this.ref  = ref;
 		}
diff --git a/src/runtime/java/org/grammaticalframework/pgf/ParseError.java b/src/runtime/java/org/grammaticalframework/pgf/ParseError.java
new file mode 100644
index 000000000..a527c8e47
--- /dev/null
+++ b/src/runtime/java/org/grammaticalframework/pgf/ParseError.java
@@ -0,0 +1,11 @@
+package org.grammaticalframework.pgf;
+
+public class ParseError extends Exception {
+	public ParseError(String token) {
+		super(token);
+	}
+	
+	public String getToken() {
+		return getMessage();
+	}
+}
diff --git a/src/runtime/java/org/grammaticalframework/pgf/Parser.java b/src/runtime/java/org/grammaticalframework/pgf/Parser.java
index 636deb521..8892d423a 100644
--- a/src/runtime/java/org/grammaticalframework/pgf/Parser.java
+++ b/src/runtime/java/org/grammaticalframework/pgf/Parser.java
@@ -6,20 +6,30 @@ class Parser implements Iterable<ExprProb> {
 	private Concr concr;
 	private String s;
 	private String startCat;
+	private ExprIterator iter;
 
-	public Parser(Concr concr, String startCat, String s) {
+	public Parser(Concr concr, String startCat, String s) throws ParseError {
 		this.concr    = concr;
 		this.startCat = startCat;
 		this.s        = s;
+		this.iter     = parse(concr, startCat, s);
 	}
 
 	public Iterator<ExprProb> iterator() {
-		ExprIterator iter = parse(concr, startCat, s);
 		if (iter == null) {
-			throw new PGFError("The sentence cannot be parsed");
+			// If someone has asked for a second iterator over
+			// the same parse results then we have to parse again.
+			try {
+				return parse(concr, startCat, s);
+			} catch (ParseError e) {
+				return null;
+			}
+		} else {
+			ExprIterator tmp_iter = iter;
+			iter = null;
+			return tmp_iter;
 		}
-		return iter;
 	}
 
-	static native ExprIterator parse(Concr concr, String startCat, String s);
+	static native ExprIterator parse(Concr concr, String startCat, String s) throws ParseError;
 }