introduce a signalling exception and improve error messages

[org.ibex.xt-crawshaw.git] / src / java / org / ibex / xt / JSElement.java

diff --git a/src/java/org/ibex/xt/JSElement.java b/src/java/org/ibex/xt/JSElement.java
index cfa1a1f..c6eee6e 100644 (file)
--- a/src/java/org/ibex/xt/JSElement.java
+++ b/src/java/org/ibex/xt/JSElement.java
@@ -9,6 +9,7 @@ import java.util.*;
 import org.ibex.util.*;
 import org.ibex.js.JS;
 import org.ibex.js.JSScope;
+import org.ibex.js.JSExn;
 
 public class JSElement extends JSScope implements XML.Element {
     protected XML.Element wrapped;
@@ -42,7 +43,7 @@ public class JSElement extends JSScope implements XML.Element {
                 declare(a.getKey(i));
                 put(a.getKey(i), eval(a.getVal(i)));
             }
-        } catch (Exception e) { throw new RuntimeException(e); }
+        } catch (JSExn e) { throw new Exn(e); }
     }
 
     private Object eval(String s) {
@@ -58,9 +59,9 @@ public class JSElement extends JSScope implements XML.Element {
                   app instanceof String ||
                   app instanceof Number ||
                   app instanceof Boolean))
-                throw new RuntimeException("javascripts within ${...} can only return " +
-                                           "strings, numbers, and booleans; not a " +
-                                           app.getClass().getName());
+                throw new Exn("javascripts within ${...} can only return " +
+                              "strings, numbers, and booleans; not a " +
+                              app.getClass().getName());
 
             ret.append(app == null ? "null" : app.toString());
         }
@@ -72,9 +73,11 @@ public class JSElement extends JSScope implements XML.Element {
         try {
             return JS.eval(JS.cloneWithNewParentScope(
                            JS.fromReader("input", 0, new StringReader(s)), this));
-        } catch (Exception e) {
+        } catch (IOException e) {
             e.printStackTrace();
-            throw new RuntimeException(e);
+            throw new Exn("impossible IOException, reading from StringReader");
+        } catch (JSExn e) {
+            throw new Exn(e);
         }
     }
 
@@ -147,4 +150,10 @@ public class JSElement extends JSScope implements XML.Element {
             return i >= a.attrSize() ? b.getUri(i-a.attrSize()) : a.getUri(i); }
         public int attrSize() { return a.attrSize() + b.attrSize(); }
     }
+
+    public static class Exn extends RuntimeException {
+        public Exn(String cause) { super(cause); }
+        public Exn(JSExn e) { super(e); }
+        public String toString() { return "JSElement.Exn: "+getMessage(); }
+    }
 }