/interpreter/tags/at2-build060407/src/edu/vub/at/objects/symbiosis/JavaPackage.java

  1/**
  2 * AmbientTalk/2 Project
  3 * JavaPackage.java created on 19-nov-2006 at 12:31:39
  4 * (c) Programming Technology Lab, 2006 - 2007
  5 * Authors: Tom Van Cutsem & Stijn Mostinckx
  6 * 
  7 * Permission is hereby granted, free of charge, to any person
  8 * obtaining a copy of this software and associated documentation
  9 * files (the "Software"), to deal in the Software without
 10 * restriction, including without limitation the rights to use,
 11 * copy, modify, merge, publish, distribute, sublicense, and/or
 12 * sell copies of the Software, and to permit persons to whom the
 13 * Software is furnished to do so, subject to the following
 14 * conditions:
 15 *
 16 * The above copyright notice and this permission notice shall be
 17 * included in all copies or substantial portions of the Software.
 18 *
 19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 20 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 21 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 22 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 23 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 24 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 25 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 26 * OTHER DEALINGS IN THE SOFTWARE.
 27 */
 28package edu.vub.at.objects.symbiosis;
 29
 30import edu.vub.at.exceptions.InterpreterException;
 31import edu.vub.at.exceptions.XClassNotFound;
 32import edu.vub.at.objects.ATContext;
 33import edu.vub.at.objects.ATObject;
 34import edu.vub.at.objects.ATStripe;
 35import edu.vub.at.objects.ATTable;
 36import edu.vub.at.objects.coercion.NativeStripes;
 37import edu.vub.at.objects.grammar.ATSymbol;
 38import edu.vub.at.objects.mirrors.PrimitiveMethod;
 39import edu.vub.at.objects.mirrors.Reflection;
 40import edu.vub.at.objects.natives.FieldMap;
 41import edu.vub.at.objects.natives.MethodDictionary;
 42import edu.vub.at.objects.natives.NATNumber;
 43import edu.vub.at.objects.natives.NATObject;
 44import edu.vub.at.objects.natives.NATTable;
 45import edu.vub.at.objects.natives.NATText;
 46import edu.vub.at.objects.natives.grammar.AGSymbol;
 47
 48import java.util.LinkedList;
 49import java.util.Vector;
 50
 51/**
 52 * A JavaPackage represents (part of) a Java package name and serves the same purpose
 53 * as AmbientTalk Namespace objects, but for loading Java classes rather than AT objects.
 54 * 
 55 * The behaviour of a JavaPackage object relies on Java naming conventions for automatic
 56 * loading of classes. If some Java code does not follow the naming conventions, then explicit
 57 * loading of packages or classes must be done via a JavaPackage's provided base-level methods.
 58 * 
 59 * Selecting a field f from a JavaPackage encapsulating the path p has the following semantics:
 60 *  - if f starts with an uppercase symbol, the field access is interpreted as a class reference:
 61 *    The JavaPackage tries to load the class p.f.
 62 *    If the class does not exist, an XSelectorNotFound exception is thrown.
 63 *  - if f starts with a lowercase symbol, the field access is interpreted as a subpackage reference:
 64 *    The JavaPackage creates a new field referring to a JavaPackage whose path equals 'p.f.'
 65 *    
 66 * JavaPackage instances are isolates, hence, they are pass-by-copy.
 67 * 
 68 * @author tvcutsem
 69 */
 70public final class JavaPackage extends NATObject {
 71
 72	private static final String _PKG_SEP_ = ".";
 73
 74	/** def class(name) { nil } */
 75	private static final PrimitiveMethod _PRIM_CLS_ = new PrimitiveMethod(
 76			AGSymbol.jAlloc("class"), NATTable.atValue(new ATObject[] { AGSymbol.jAlloc("name")})) {
 77		public ATObject base_apply(ATTable arguments, ATContext ctx) throws InterpreterException {
 78			return ((JavaPackage)ctx.base_getLexicalScope()).base_class(arguments.base_at(NATNumber.ONE).asSymbol());
 79		}
 80	};
 81	/** def package(name) { nil } */
 82	private static final PrimitiveMethod _PRIM_PKG_ = new PrimitiveMethod(
 83			AGSymbol.jAlloc("package"), NATTable.atValue(new ATObject[] { AGSymbol.jAlloc("name")})) {
 84		public ATObject base_apply(ATTable arguments, ATContext ctx) throws InterpreterException {
 85			return ((JavaPackage)ctx.base_getLexicalScope()).base_package(arguments.base_at(NATNumber.ONE).asSymbol());
 86		}
 87	};
 88	
 89	private final String path_;
 90	
 91	/**
 92	 * A JavaPackage object encapsulates a package path.
 93	 * A package path is a '.'-separated string, always ending with a '.'
 94	 * The jlobby root package has an empty package path
 95	 * 
 96	 * A JavaPackage is initialized as an AT/2 isolate object.
 97	 * 
 98	 * @param path the pathname of this JavaPackage, e.g. 'java.' or 'java.lang.'
 99	 */
100	public JavaPackage(String path) {
101		super(new ATStripe[] { NativeStripes._ISOLATE_ });
102		path_ = path;
103		try {
104			super.meta_addMethod(_PRIM_CLS_);
105			super.meta_addMethod(_PRIM_PKG_);
106		} catch (InterpreterException e) {
107			throw new RuntimeException("Failed to initialize a JavaPackage: " + e.getMessage());
108		}
109	}
110	
111	/**
112	 * Private constructor used only for cloning
113	 */
114	private JavaPackage(FieldMap map,
115			  		   Vector state,
116			  		   LinkedList customFields,
117			  		   MethodDictionary methodDict,
118			  		   ATObject dynamicParent,
119			  		   ATObject lexicalParent,
120			  		   byte flags,
121			  		   ATStripe[] stripes,
122			  		   String path) throws InterpreterException {
123		super(map, state, customFields, methodDict, dynamicParent, lexicalParent, flags, stripes);
124		path_ = path;
125	}
126	
127	/**
128	 * For a JavaPackage object, doesNotUnderstand triggers the querying of the Java classpath
129	 * to load classes corresponding to the missing selector. Depending on the case of the
130	 * selector's first letter, the access is interpreted as a class or a package reference.
131	 */
132	public ATObject meta_doesNotUnderstand(ATSymbol selector) throws InterpreterException {
133		// first, convert the AmbientTalk name to a Java selector.
134		String s = selector.base_getText().asNativeText().javaValue;
135		if (Character.isUpperCase(s.charAt(0))) {
136			// the field access is interpreted as a class reference
137			return base_class(selector);
138		} else {
139			// the field access is interpreted as a package reference
140			return base_package(selector);
141		}
142	}
143
144	public NATText meta_print() throws InterpreterException {
145		return NATText.atValue("<jpackage:"+path_+">");
146	}
147	
148	protected NATObject createClone(FieldMap map,
149			  					Vector state,
150			  					LinkedList customFields,
151			  					MethodDictionary methodDict,
152			  					ATObject dynamicParent,
153			  					ATObject lexicalParent,
154			  					byte flags, ATStripe[] stripes) throws InterpreterException {
155		return new JavaPackage(map,
156    		  				      state,
157    		  				      customFields,
158    		  				      methodDict,
159    		  				      dynamicParent,
160    		  				      lexicalParent,
161    		  				      flags,
162    		  				      stripes,
163    		  				      path_);
164	}
165	
166	/**
167	 * Allows the AT programmer to explicitly load a class. This might be necessary if the
168	 * class starts with a lowercase letter.
169	 */
170	public ATObject base_class(ATSymbol selector) throws InterpreterException {
171		// try to see if a class corresponding to the selector prefixed with
172		// this package's pathname exists
173		String qualifiedClassname = path_ + Reflection.upSelector(selector);
174		try {
175			Class c = Class.forName(qualifiedClassname);
176		    JavaClass jc = JavaClass.wrapperFor(c);
177			// bind the new class to the selector within this JavaPackage
178			this.meta_defineField(selector, jc);
179			return jc;
180		} catch (ClassNotFoundException e) {
181			throw new XClassNotFound(qualifiedClassname, e);
182		}
183	}
184	
185	/**
186	 * Allows the AT programmer to explicitly load a package. This might be necessary if the
187	 * package starts with an uppercase letter.
188	 */
189	public ATObject base_package(ATSymbol selector) throws InterpreterException {
190         // define a new Java package with a trailing '.'
191		JavaPackage jpkg = new JavaPackage(path_ + Reflection.upSelector(selector) + _PKG_SEP_);
192		this.meta_defineField(selector, jpkg);
193		return jpkg;
194	}
195	
196}