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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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*****************************************************************************/
package bsh;
import java.lang.reflect.Field;
/**
*
* An LHS is a wrapper for an variable, field, or property. It ordinarily holds
* the "left hand side" of an assignment and may be either resolved to a value
* or assigned a value.
*
*
*
* There is one special case here termed METHOD_EVAL where the LHS is used in an
* intermediate evaluation of a chain of suffixes and wraps a method invocation.
* In this case it may only be resolved to a value and cannot be assigned. (You
* can't assign a value to the result of a method call e.g. "foo() = 5;").
*
*/
class LHS implements ParserConstants, java.io.Serializable {
private static final long serialVersionUID = 1L;
NameSpace nameSpace;
/** The assignment should be to a local variable */
boolean localVar;
/**
* Identifiers for the various types of LHS.
*/
static final int VARIABLE = 0, FIELD = 1, PROPERTY = 2, INDEX = 3,
METHOD_EVAL = 4;
int type;
String varName;
String propName;
Field field;
Object object;
int index;
/**
* Variable LHS constructor.
*/
LHS(NameSpace nameSpace, String varName) {
throw new Error("namespace lhs");
/*
* type = VARIABLE; this.varName = varName; this.nameSpace = nameSpace;
*/
}
/**
* @param localVar
* if true the variable is set directly in the This reference's
* local scope. If false recursion to look for the variable
* definition in parent's scope is allowed. (e.g. the default
* case for undefined vars going to global).
*/
LHS(NameSpace nameSpace, String varName, boolean localVar) {
type = VARIABLE;
this.localVar = localVar;
this.varName = varName;
this.nameSpace = nameSpace;
}
/**
* Static field LHS Constructor. This simply calls Object field constructor
* with null object.
*/
LHS(Field field) {
type = FIELD;
this.object = null;
this.field = field;
}
/**
* Object field LHS Constructor.
*/
LHS(Object object, Field field) {
if (object == null)
throw new NullPointerException("constructed empty LHS");
type = FIELD;
this.object = object;
this.field = field;
}
/**
* Object property LHS Constructor.
*/
LHS(Object object, String propName) {
if (object == null)
throw new NullPointerException("constructed empty LHS");
type = PROPERTY;
this.object = object;
this.propName = propName;
}
/**
* Array index LHS Constructor.
*/
LHS(Object array, int index) {
if (array == null)
throw new NullPointerException("constructed empty LHS");
type = INDEX;
this.object = array;
this.index = index;
}
public Object getValue() throws UtilEvalError {
if (type == VARIABLE)
return nameSpace.getVariable(varName);
if (type == FIELD)
try {
Object o = field.get(object);
return Primitive.wrap(o, field.getType());
} catch (IllegalAccessException e2) {
throw new UtilEvalError("Can't read field: " + field);
}
if (type == PROPERTY)
try {
return Reflect.getObjectProperty(object, propName);
} catch (ReflectError e) {
Interpreter.debug(e.getMessage());
throw new UtilEvalError("No such property: " + propName);
}
if (type == INDEX)
try {
return Reflect.getIndex(object, index);
} catch (Exception e) {
throw new UtilEvalError("Array access: " + e);
}
throw new InterpreterError("LHS type");
}
/**
* Assign a value to the LHS.
*/
public Object assign(Object val, boolean strictJava) throws UtilEvalError {
if (type == VARIABLE) {
// Set the variable in namespace according to localVar
// flag
if (localVar)
nameSpace.setLocalVariable(varName, val, strictJava);
else
nameSpace.setVariable(varName, val, strictJava);
} else if (type == FIELD) {
try {
Object fieldVal = val instanceof Primitive ? ((Primitive) val).getValue() : val;
// This should probably be in Reflect.java
ReflectManager.RMSetAccessible(field);
field.set(object, fieldVal);
return val;
} catch (NullPointerException e) {
throw new UtilEvalError("LHS (" + field.getName() + ") not a static field.");
} catch (IllegalAccessException e2) {
throw new UtilEvalError("LHS (" + field.getName() + ") can't access field: " + e2);
} catch (IllegalArgumentException e3) {
String type = val instanceof Primitive ? ((Primitive) val).getType().getName() : val.getClass().getName();
throw new UtilEvalError("Argument type mismatch. " + (val == null ? "null" : type) + " not assignable to field " + field.getName());
}
} else if (type == PROPERTY) {
/*
* if ( object instanceof Hashtable )
* ((Hashtable)object).put(propName, val);
*/
CollectionManager cm = CollectionManager.getCollectionManager();
if (cm.isMap(object))
cm.putInMap(object/* map */, propName, val);
else
try {
Reflect.setObjectProperty(object, propName, val);
} catch (ReflectError e) {
Interpreter.debug("Assignment: " + e.getMessage());
throw new UtilEvalError("No such property: " + propName);
}
} else if (type == INDEX)
try {
Reflect.setIndex(object, index, val);
} catch (UtilTargetError e1) { // pass along target
// error
throw e1;
} catch (Exception e) {
throw new UtilEvalError("Assignment: " + e.getMessage());
}
else
throw new InterpreterError("unknown lhs");
return val;
}
public String toString() {
return "LHS: " + ((field != null) ? "field = " + field.toString() : "") + (varName != null ? " varName = " + varName : "")
+ (nameSpace != null ? " nameSpace = " + nameSpace.toString() : "");
}
}
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