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/interpreter/tags/at2dist110511/src/edu/vub/at/objects/natives/grammar/AGUnquoteSplice.java

http://ambienttalk.googlecode.com/
Java | 115 lines | 45 code | 16 blank | 54 comment | 0 complexity | f55ca3823aaafc784c1d694564e651f0 MD5 | raw file
  1/**
  2 * AmbientTalk/2 Project
  3 * AGUnquoteSplice.java created on 26-jul-2006 at 16:31:07
  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.natives.grammar;
 29
 30import edu.vub.at.exceptions.InterpreterException;
 31import edu.vub.at.exceptions.XIllegalQuote;
 32import edu.vub.at.exceptions.XIllegalUnquote;
 33import edu.vub.at.objects.ATContext;
 34import edu.vub.at.objects.ATObject;
 35import edu.vub.at.objects.grammar.ATExpression;
 36import edu.vub.at.objects.grammar.ATUnquoteSplice;
 37import edu.vub.at.objects.natives.NATText;
 38import edu.vub.util.TempFieldGenerator;
 39
 40import java.util.Set;
 41
 42/**
 43 * The native implementation of an unquote-splice AG element.
 44 * Example: <tt>#@[1,2,3]</tt>
 45 * 
 46 * @author tvcutsem
 47 */
 48public class AGUnquoteSplice extends AGExpression implements ATUnquoteSplice {
 49
 50	private final ATExpression uqsExp_;
 51	
 52	public AGUnquoteSplice(ATExpression exp) {
 53		uqsExp_ = exp;
 54	}
 55	
 56	public ATExpression base_expression() { return uqsExp_; }
 57
 58	/**
 59	 * An unquotation cannot be evaluated, but rather gives rise to an XIllegalUnquote exception.
 60	 * This is because an unquotation should always be nested within a quotation.
 61	 * 
 62	 * AGUQS(exp).eval(ctx) = ERROR
 63	 */
 64	public ATObject meta_eval(ATContext ctx) throws InterpreterException {
 65		throw new XIllegalUnquote(uqsExp_);
 66	}
 67
 68	/**
 69	 * Quoting a spliced unquotation means evaluating its contained expression, and returning
 70	 * its value as the result of the quote. A spliced unquotation can normally only
 71	 * be invoked where a table or begin is expected. The resulting table is replaced by the result of
 72	 * evaluating the unquote-splice's encapsulated expression.
 73	 * 
 74	 * It is the table's responsibility to query an AGUnquoteSplice element for its expression and deal with the inlining appropriately.
 75	 */
 76	public ATObject meta_quote(ATContext ctx) throws InterpreterException {
 77		throw new XIllegalQuote(uqsExp_.meta_print().javaValue);
 78	}
 79	
 80	public NATText meta_print() throws InterpreterException {
 81		return NATText.atValue("#@("+ uqsExp_.meta_print().javaValue + ")");
 82	}
 83	
 84	public NATText impl_asCode(TempFieldGenerator objectMap) throws InterpreterException {
 85		return this.impl_asUnquotedCode(objectMap);
 86	}
 87	
 88	public NATText impl_asUnquotedCode(TempFieldGenerator objectMap) throws InterpreterException {
 89		return NATText.atValue("#@("+ uqsExp_.impl_asUnquotedCode(objectMap).javaValue + ")");
 90	}
 91	
 92	public boolean isUnquoteSplice() {
 93		return true;
 94	}
 95	
 96	public ATUnquoteSplice asUnquoteSplice() {
 97		return this;
 98	}
 99	
100	/**
101	 * FV(#@exp) = FV(exp)
102	 */
103	public Set impl_freeVariables() throws InterpreterException {
104		return uqsExp_.impl_freeVariables();
105	}
106	
107	/**
108	 * Turn unquotation back into quotation.
109	 * E.g. `(x + #@y) => y is considered a free variable.
110	 */
111	public Set impl_quotedFreeVariables() throws InterpreterException {
112		return this.impl_freeVariables();
113	}
114
115}