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* This file is part of the BeanShell Java Scripting distribution. *
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* Patrick Niemeyer ([email protected]) *
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* http://www.pat.net/~pat/ *
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package bsh;
import java.util.Vector;
class BSHTryStatement extends SimpleNode {
BSHTryStatement(int id) {
super(id);
}
public Object eval(CallStack callstack, Interpreter interpreter) throws EvalError {
BSHBlock tryBlock = ((BSHBlock) jjtGetChild(0));
Vector catchParams = new Vector();
Vector catchBlocks = new Vector();
int nchild = jjtGetNumChildren();
Node node = null;
int i = 1;
while ((i < nchild) && ((node = jjtGetChild(i++)) instanceof BSHFormalParameter)) {
catchParams.addElement(node);
catchBlocks.addElement(jjtGetChild(i++));
node = null;
}
// finaly block
BSHBlock finallyBlock = null;
if (node != null)
finallyBlock = (BSHBlock) node;
// Why both of these?
TargetError target = null;
Throwable thrown = null;
Object ret = null;
/*
* Evaluate the contents of the try { } block and catch any
* resulting TargetErrors generated by the script. We save the
* callstack depth and if an exception is thrown we pop back to
* that depth before contiuing. The exception short circuited
* any intervening method context pops.
*
* Note: we the stack info... what do we do with it? append to
* exception message?
*/
int callstackDepth = callstack.depth();
try {
ret = tryBlock.eval(callstack, interpreter);
} catch (TargetError e) {
target = e;
String stackInfo = "Bsh Stack: ";
while (callstack.depth() > callstackDepth)
stackInfo += "\t" + callstack.pop() + "\n";
}
// unwrap the target error
if (target != null)
thrown = target.getTarget();
// If we have an exception, find a catch
if (thrown != null) {
int n = catchParams.size();
for (i = 0; i < n; i++) {
// Get catch block
BSHFormalParameter fp = (BSHFormalParameter) catchParams.elementAt(i);
// Should cache this subject to classloader
// change message
// Evaluation of the formal parameter simply
// resolves its
// type via the specified namespace.. it doesn't
// modify the
// namespace.
fp.eval(callstack, interpreter);
if (fp.type == null && interpreter.getStrictJava())
throw new EvalError("(Strict Java) Untyped catch block", this, callstack);
// If the param is typed check assignability
if (fp.type != null)
try {
thrown = (Throwable) Types.castObject(thrown/* rsh */, fp.type/* lhsType */, Types.ASSIGNMENT);
} catch (UtilEvalError e) {
/*
* Catch the mismatch and
* continue to try the next
* Note: this is innefficient,
* should have an
* isAssignableFrom() that
* doesn't throw // TODO: we do
* now have a way to test
* assignment // in
* castObject(), use it?
*/
continue;
}
// Found match, execute catch block
BSHBlock cb = (BSHBlock) (catchBlocks.elementAt(i));
// Prepare to execute the block.
// We must create a new BlockNameSpace to hold
// the catch
// parameter and swap it on the stack after
// initializing it.
NameSpace enclosingNameSpace = callstack.top();
BlockNameSpace cbNameSpace = new BlockNameSpace(enclosingNameSpace);
try {
if (fp.type == BSHFormalParameter.UNTYPED)
// set an untyped variable
// directly in the block
cbNameSpace.setBlockVariable(fp.name, thrown);
else {
// set a typed variable
// (directly in the block)
Modifiers modifiers = new Modifiers();
cbNameSpace.setTypedVariable(fp.name, fp.type, thrown, new Modifiers()/* none */);
}
} catch (UtilEvalError e) {
throw new InterpreterError("Unable to set var in catch block namespace.");
}
// put cbNameSpace on the top of the stack
callstack.swap(cbNameSpace);
try {
ret = cb.eval(callstack, interpreter);
} finally {
// put it back
callstack.swap(enclosingNameSpace);
}
target = null; // handled target
break;
}
}
// evaluate finally block
if (finallyBlock != null)
ret = finallyBlock.eval(callstack, interpreter);
// exception fell through, throw it upward...
if (target != null)
throw target;
if (ret instanceof ReturnControl)
return ret;
else
return Primitive.VOID;
}
}
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