whitespace.java

java1.6众多例子参考

		// Skip to next rule (there might not be any)...
		idx++;
	    }
	}

	// The rules vector could be empty if first rule has strength RULE_ALL
	if (rules.size() == 0) {
	    return defaultAction;
	}

	// Now work backwards and strip away all rules that have the same
	// action as the default rule (no reason the check them at the end).
	do {
	    currentRule = (WhitespaceRule)rules.lastElement();
	    if (currentRule.getAction() == defaultAction) {
		rules.removeElementAt(rules.size() - 1);
	    }
	    else {
		break;
	    }
	} while (rules.size() > 0);
	
	// Signal that whitespace detection predicate must be used.
	return defaultAction;
    }

    public static void compileStripSpace(BranchHandle strip[], 
					 int sCount,
					 InstructionList il) {
	final InstructionHandle target = il.append(ICONST_1);
	il.append(IRETURN);
	for (int i = 0; i < sCount; i++) {
	    strip[i].setTarget(target);
	}
    }

    public static void compilePreserveSpace(BranchHandle preserve[], 
					    int pCount,
					    InstructionList il) {
	final InstructionHandle target = il.append(ICONST_0);
	il.append(IRETURN);
	for (int i = 0; i < pCount; i++) {
	    preserve[i].setTarget(target);
	}
    }

    /*
    private static void compileDebug(ClassGenerator classGen,
				     InstructionList il) {
	final ConstantPoolGen cpg = classGen.getConstantPool();
	final int prt = cpg.addMethodref("java/lang/System/out",
					 "println",
					 "(Ljava/lang/String;)V");
	il.append(DUP);
	il.append(new INVOKESTATIC(prt));
    }
    */

    /**
     * Compiles the predicate method
     */
    private static void compilePredicate(Vector rules,
					 int defaultAction,
					 ClassGenerator classGen) {
	final ConstantPoolGen cpg = classGen.getConstantPool();
	final InstructionList il = new InstructionList();
	final XSLTC xsltc = classGen.getParser().getXSLTC();

	// private boolean Translet.stripSpace(int type) - cannot be static
	final MethodGenerator stripSpace =
	    new MethodGenerator(ACC_PUBLIC | ACC_FINAL ,
			com.sun.org.apache.bcel.internal.generic.Type.BOOLEAN, 
			new com.sun.org.apache.bcel.internal.generic.Type[] {
			    Util.getJCRefType(DOM_INTF_SIG),
			    com.sun.org.apache.bcel.internal.generic.Type.INT,
			    com.sun.org.apache.bcel.internal.generic.Type.INT
			},
			new String[] { "dom","node","type" },
			"stripSpace",classGen.getClassName(),il,cpg);

	classGen.addInterface("com/sun/org/apache/xalan/internal/xsltc/StripFilter");

	final int paramDom = stripSpace.getLocalIndex("dom");
	final int paramCurrent = stripSpace.getLocalIndex("node");
	final int paramType = stripSpace.getLocalIndex("type");

	BranchHandle strip[] = new BranchHandle[rules.size()];
	BranchHandle preserve[] = new BranchHandle[rules.size()];
	int sCount = 0;
	int pCount = 0;

	// Traverse all strip/preserve rules
	for (int i = 0; i<rules.size(); i++) {
	    // Get the next rule in the prioritised list
	    WhitespaceRule rule = (WhitespaceRule)rules.elementAt(i);

	    // Returns the namespace for a node in the DOM
	    final int gns = cpg.addInterfaceMethodref(DOM_INTF,
						      "getNamespaceName",
						      "(I)Ljava/lang/String;");

	    final int strcmp = cpg.addMethodref("java/lang/String",
						"compareTo",
						"(Ljava/lang/String;)I");

	    // Handle elements="ns:*" type rule
	    if (rule.getStrength() == RULE_NAMESPACE) {
		il.append(new ALOAD(paramDom));
		il.append(new ILOAD(paramCurrent));
		il.append(new INVOKEINTERFACE(gns,2));
		il.append(new PUSH(cpg, rule.getNamespace()));
		il.append(new INVOKEVIRTUAL(strcmp));
		il.append(ICONST_0);

		if (rule.getAction() == STRIP_SPACE) {
		    strip[sCount++] = il.append(new IF_ICMPEQ(null));
		}
		else {
		    preserve[pCount++] = il.append(new IF_ICMPEQ(null));
		}
	    }
	    // Handle elements="ns:el" type rule
	    else if (rule.getStrength() == RULE_ELEMENT) {
		// Create the QName for the element
		final Parser parser = classGen.getParser();
		QName qname;
		if (rule.getNamespace() != Constants.EMPTYSTRING )
		    qname = parser.getQName(rule.getNamespace(), null,
					    rule.getElement());
		else
		    qname = parser.getQName(rule.getElement());

		// Register the element.
		final int elementType = xsltc.registerElement(qname);
		il.append(new ILOAD(paramType));
		il.append(new PUSH(cpg, elementType));

		// Compare current node type with wanted element type
		if (rule.getAction() == STRIP_SPACE)
		    strip[sCount++] = il.append(new IF_ICMPEQ(null));
		else
		    preserve[pCount++] = il.append(new IF_ICMPEQ(null));
	    }
	}

	if (defaultAction == STRIP_SPACE) {
	    compileStripSpace(strip, sCount, il);
	    compilePreserveSpace(preserve, pCount, il);
	}
	else {
	    compilePreserveSpace(preserve, pCount, il);
	    compileStripSpace(strip, sCount, il);
	}

	stripSpace.stripAttributes(true);
	stripSpace.setMaxLocals();
	stripSpace.setMaxStack();
	stripSpace.removeNOPs();

	classGen.addMethod(stripSpace.getMethod());
    }

    /**
     * Compiles the predicate method
     */
    private static void compileDefault(int defaultAction,
				       ClassGenerator classGen) {
	final ConstantPoolGen cpg = classGen.getConstantPool();
	final InstructionList il = new InstructionList();
	final XSLTC xsltc = classGen.getParser().getXSLTC();

	// private boolean Translet.stripSpace(int type) - cannot be static
	final MethodGenerator stripSpace =
	    new MethodGenerator(ACC_PUBLIC | ACC_FINAL ,
			com.sun.org.apache.bcel.internal.generic.Type.BOOLEAN, 
			new com.sun.org.apache.bcel.internal.generic.Type[] {
			    Util.getJCRefType(DOM_INTF_SIG),
			    com.sun.org.apache.bcel.internal.generic.Type.INT,
			    com.sun.org.apache.bcel.internal.generic.Type.INT
			},
			new String[] { "dom","node","type" },
			"stripSpace",classGen.getClassName(),il,cpg);

	classGen.addInterface("com/sun/org/apache/xalan/internal/xsltc/StripFilter");

	if (defaultAction == STRIP_SPACE)
	    il.append(ICONST_1);
	else
	    il.append(ICONST_0);
	il.append(IRETURN);

	stripSpace.stripAttributes(true);
	stripSpace.setMaxLocals();
	stripSpace.setMaxStack();
	stripSpace.removeNOPs();

	classGen.addMethod(stripSpace.getMethod());
    }


    /**
     * Takes a vector of WhitespaceRule objects and generates a predicate
     * method. This method returns the translets default action for handling
     * whitespace text-nodes:
     *    - USE_PREDICATE  (run the method generated by this method)
     *    - STRIP_SPACE    (always strip whitespace text-nodes)
     *    - PRESERVE_SPACE (always preserve whitespace text-nodes)
     */
    public static int translateRules(Vector rules,
				     ClassGenerator classGen) {
	// Get the core rules in prioritized order
	final int defaultAction = prioritizeRules(rules);
	// The rules vector may be empty after prioritising
	if (rules.size() == 0) {
	    compileDefault(defaultAction,classGen);
	    return defaultAction;
	}
	// Now - create a predicate method and sequence through rules...
	compilePredicate(rules, defaultAction, classGen);
	// Return with the translets required action (
	return USE_PREDICATE;
    }

    /**
     * Sorts a range of rules with regard to PRIORITY only
     */
    private static void quicksort(Vector rules, int p, int r) {
	while (p < r) {
	    final int q = partition(rules, p, r);
	    quicksort(rules, p, q);
	    p = q + 1;
	}
    }
    
    /**
     * Used with quicksort method above
     */
    private static int partition(Vector rules, int p, int r) {
	final WhitespaceRule x = (WhitespaceRule)rules.elementAt((p+r) >>> 1);
	int i = p - 1, j = r + 1;
	while (true) {
	    while (x.compareTo((WhitespaceRule)rules.elementAt(--j)) < 0) {
	    }
	    while (x.compareTo((WhitespaceRule)rules.elementAt(++i)) > 0) {
	    }
	    if (i < j) {
		final WhitespaceRule tmp = (WhitespaceRule)rules.elementAt(i);
		rules.setElementAt(rules.elementAt(j), i);
		rules.setElementAt(tmp, j);
	    }
	    else {
		return j;
	    }
	}
    }
    
    /**
     * Type-check contents/attributes - nothing to do...
     */
    public Type typeCheck(SymbolTable stable) throws TypeCheckError {
	return Type.Void; // We don't return anything.
    }

    /**
     * This method should not produce any code
     */
    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
    }
}