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ForEach.javaAPI DocApache Tomcat 6.0.1414174Fri Jul 20 04:20:36 BST 2007org.apache.jasper.tagplugins.jstl.core

ForEach

public final class ForEach extends Object implements TagPlugin

Fields Summary
private boolean
hasVar
private boolean
hasBegin
private boolean
hasEnd
private boolean
hasStep
Constructors Summary
Methods Summary
private voiddoCollection(TagPluginContext ctxt)
Generate codes for Collections The pseudo code is:

        
        ctxt.generateImport("java.util.*");
        generateIterators(ctxt);
        
        String itemsV = ctxt.getTemporaryVariableName();
        ctxt.generateJavaSource("Object " + itemsV + "= ");
        ctxt.generateAttribute("items");
        ctxt.generateJavaSource(";");
        
        String indexV=null, beginV=null, endV=null, stepV=null;
        if (hasBegin) {
            beginV = ctxt.getTemporaryVariableName();
            ctxt.generateJavaSource("int " + beginV + " = ");
            ctxt.generateAttribute("begin");
            ctxt.generateJavaSource(";");
        }
        if (hasEnd) {
            indexV = ctxt.getTemporaryVariableName();
            ctxt.generateJavaSource("int " + indexV + " = 0;");
            endV = ctxt.getTemporaryVariableName();
            ctxt.generateJavaSource("int " + endV + " = ");
            ctxt.generateAttribute("end");
            ctxt.generateJavaSource(";");
        }
        if (hasStep) {
            stepV = ctxt.getTemporaryVariableName();
            ctxt.generateJavaSource("int " + stepV + " = ");
            ctxt.generateAttribute("step");
            ctxt.generateJavaSource(";");
        }
        
        String iterV = ctxt.getTemporaryVariableName();
        ctxt.generateJavaSource("Iterator " + iterV + " = null;");
        // Object[]
        ctxt.generateJavaSource("if (" + itemsV + " instanceof Object[])");
        ctxt.generateJavaSource(iterV + "=toIterator((Object[])" + itemsV + ");");
        // boolean[]
        ctxt.generateJavaSource("else if (" + itemsV + " instanceof boolean[])");
        ctxt.generateJavaSource(iterV + "=toIterator((boolean[])" + itemsV + ");");
        // byte[]
        ctxt.generateJavaSource("else if (" + itemsV + " instanceof byte[])");
        ctxt.generateJavaSource(iterV + "=toIterator((byte[])" + itemsV + ");");
        // char[]
        ctxt.generateJavaSource("else if (" + itemsV + " instanceof char[])");
        ctxt.generateJavaSource(iterV + "=toIterator((char[])" + itemsV + ");");
        // short[]
        ctxt.generateJavaSource("else if (" + itemsV + " instanceof short[])");
        ctxt.generateJavaSource(iterV + "=toIterator((short[])" + itemsV + ");");
        // int[]
        ctxt.generateJavaSource("else if (" + itemsV + " instanceof int[])");
        ctxt.generateJavaSource(iterV + "=toIterator((int[])" + itemsV + ");");
        // long[]
        ctxt.generateJavaSource("else if (" + itemsV + " instanceof long[])");
        ctxt.generateJavaSource(iterV + "=toIterator((long[])" + itemsV + ");");
        // float[]
        ctxt.generateJavaSource("else if (" + itemsV + " instanceof float[])");
        ctxt.generateJavaSource(iterV + "=toIterator((float[])" + itemsV + ");");
        // double[]
        ctxt.generateJavaSource("else if (" + itemsV + " instanceof double[])");
        ctxt.generateJavaSource(iterV + "=toIterator((double[])" + itemsV + ");");
        
        // Collection
        ctxt.generateJavaSource("else if (" + itemsV + " instanceof Collection)");
        ctxt.generateJavaSource(iterV + "=((Collection)" + itemsV + ").iterator();");
        
        // Iterator
        ctxt.generateJavaSource("else if (" + itemsV + " instanceof Iterator)");
        ctxt.generateJavaSource(iterV + "=(Iterator)" + itemsV + ";");
        
        // Enumeration
        ctxt.generateJavaSource("else if (" + itemsV + " instanceof Enumeration)");
        ctxt.generateJavaSource(iterV + "=toIterator((Enumeration)" + itemsV + ");");
        
        // Map
        ctxt.generateJavaSource("else if (" + itemsV + " instanceof Map)");
        ctxt.generateJavaSource(iterV + "=((Map)" + itemsV + ").entrySet().iterator();");
        
        if (hasBegin) {
            String tV = ctxt.getTemporaryVariableName();
            ctxt.generateJavaSource("for (int " + tV + "=" + beginV + ";" +
                    tV + ">0 && " + iterV + ".hasNext(); " +
                    tV + "--)");
            ctxt.generateJavaSource(iterV + ".next();");
        }
        
        ctxt.generateJavaSource("while (" + iterV + ".hasNext()){");
        if (hasVar) {
            ctxt.generateJavaSource("_jspx_page_context.setAttribute(");
            ctxt.generateAttribute("var");
            ctxt.generateJavaSource(", " + iterV + ".next());");
        }
        
        ctxt.generateBody();
        
        if (hasStep) {
            String tV = ctxt.getTemporaryVariableName();
            ctxt.generateJavaSource("for (int " + tV + "=" + stepV + "-1;" +
                    tV + ">0 && " + iterV + ".hasNext(); " +
                    tV + "--)");
            ctxt.generateJavaSource(iterV + ".next();");
        }
        if (hasEnd) {
            if (hasStep) {
                ctxt.generateJavaSource(indexV + "+=" + stepV + ";");
            }
            else {
                ctxt.generateJavaSource(indexV + "++;");
            }
            if (hasBegin) {
                ctxt.generateJavaSource("if(" + beginV + "+" + indexV +
                        ">"+ endV + ")");
            }
            else {
                ctxt.generateJavaSource("if(" + indexV + ">" + endV + ")");
            }
            ctxt.generateJavaSource("break;");
        }
        ctxt.generateJavaSource("}");	// while
public voiddoTag(TagPluginContext ctxt)

        
        String index = null;
        
        boolean hasVarStatus = ctxt.isAttributeSpecified("varStatus");
        if (hasVarStatus) {
            ctxt.dontUseTagPlugin();
            return;
        }
        
        hasVar = ctxt.isAttributeSpecified("var");
        hasBegin = ctxt.isAttributeSpecified("begin");
        hasEnd = ctxt.isAttributeSpecified("end");
        hasStep = ctxt.isAttributeSpecified("step");
        
        boolean hasItems = ctxt.isAttributeSpecified("items");
        if (hasItems) {
            doCollection(ctxt);
            return;
        }
        
        // We must have a begin and end attributes
        index = ctxt.getTemporaryVariableName();
        ctxt.generateJavaSource("for (int " + index + " = ");
        ctxt.generateAttribute("begin");
        ctxt.generateJavaSource("; " + index + " <= ");
        ctxt.generateAttribute("end");
        if (hasStep) {
            ctxt.generateJavaSource("; " + index + "+=");
            ctxt.generateAttribute("step");
            ctxt.generateJavaSource(") {");
        }
        else {
            ctxt.generateJavaSource("; " + index + "++) {");
        }
        
        // If var is specified and the body contains an EL, then sycn
        // the var attribute
        if (hasVar /* && ctxt.hasEL() */) {
            ctxt.generateJavaSource("_jspx_page_context.setAttribute(");
            ctxt.generateAttribute("var");
            ctxt.generateJavaSource(", String.valueOf(" + index + "));");
        }
        ctxt.generateBody();
        ctxt.generateJavaSource("}");
private voidgenerateIterators(TagPluginContext ctxt)
Generate iterators for data types supported in items

        
        // Object[]
        ctxt.generateDeclaration("ObjectArrayIterator", 
                "private Iterator toIterator(final Object[] a){\n" +
                "  return (new Iterator() {\n" +
                "    int index=0;\n" +
                "    public boolean hasNext() {\n" +
                "      return index < a.length;}\n" +
                "    public Object next() {\n" +
                "      return a[index++];}\n" +
                "    public void remove() {}\n" +
                "  });\n" +
                "}"
        );
        
        // boolean[]
        ctxt.generateDeclaration("booleanArrayIterator", 
                "private Iterator toIterator(final boolean[] a){\n" +
                "  return (new Iterator() {\n" +
                "    int index=0;\n" +
                "    public boolean hasNext() {\n" +
                "      return index < a.length;}\n" +
                "    public Object next() {\n" +
                "      return new Boolean(a[index++]);}\n" +
                "    public void remove() {}\n" +
                "  });\n" +
                "}"
        );
        
        // byte[]
        ctxt.generateDeclaration("byteArrayIterator", 
                "private Iterator toIterator(final byte[] a){\n" +
                "  return (new Iterator() {\n" +
                "    int index=0;\n" +
                "    public boolean hasNext() {\n" +
                "      return index < a.length;}\n" +
                "    public Object next() {\n" +
                "      return new Byte(a[index++]);}\n" +
                "    public void remove() {}\n" +
                "  });\n" +
                "}"
        );
        
        // char[]
        ctxt.generateDeclaration("charArrayIterator", 
                "private Iterator toIterator(final char[] a){\n" +
                "  return (new Iterator() {\n" +
                "    int index=0;\n" +
                "    public boolean hasNext() {\n" +
                "      return index < a.length;}\n" +
                "    public Object next() {\n" +
                "      return new Character(a[index++]);}\n" +
                "    public void remove() {}\n" +
                "  });\n" +
                "}"
        );
        
        // short[]
        ctxt.generateDeclaration("shortArrayIterator", 
                "private Iterator toIterator(final short[] a){\n" +
                "  return (new Iterator() {\n" +
                "    int index=0;\n" +
                "    public boolean hasNext() {\n" +
                "      return index < a.length;}\n" +
                "    public Object next() {\n" +
                "      return new Short(a[index++]);}\n" +
                "    public void remove() {}\n" +
                "  });\n" +
                "}"
        );
        
        // int[]
        ctxt.generateDeclaration("intArrayIterator", 
                "private Iterator toIterator(final int[] a){\n" +
                "  return (new Iterator() {\n" +
                "    int index=0;\n" +
                "    public boolean hasNext() {\n" +
                "      return index < a.length;}\n" +
                "    public Object next() {\n" +
                "      return new Integer(a[index++]);}\n" +
                "    public void remove() {}\n" +
                "  });\n" +
                "}"
        );
        
        // long[]
        ctxt.generateDeclaration("longArrayIterator", 
                "private Iterator toIterator(final long[] a){\n" +
                "  return (new Iterator() {\n" +
                "    int index=0;\n" +
                "    public boolean hasNext() {\n" +
                "      return index < a.length;}\n" +
                "    public Object next() {\n" +
                "      return new Long(a[index++]);}\n" +
                "    public void remove() {}\n" +
                "  });\n" +
                "}"
        );
        
        // float[]
        ctxt.generateDeclaration("floatArrayIterator",
                "private Iterator toIterator(final float[] a){\n" +
                "  return (new Iterator() {\n" +
                "    int index=0;\n" +
                "    public boolean hasNext() {\n" +
                "      return index < a.length;}\n" +
                "    public Object next() {\n" +
                "      return new Float(a[index++]);}\n" +
                "    public void remove() {}\n" +
                "  });\n" +
                "}"
        );
        
        // double[]
        ctxt.generateDeclaration("doubleArrayIterator",
                "private Iterator toIterator(final double[] a){\n" +
                "  return (new Iterator() {\n" +
                "    int index=0;\n" +
                "    public boolean hasNext() {\n" +
                "      return index < a.length;}\n" +
                "    public Object next() {\n" +
                "      return new Double(a[index++]);}\n" +
                "    public void remove() {}\n" +
                "  });\n" +
                "}"
        );
        
        // Enumeration
        ctxt.generateDeclaration("enumIterator",
                "private Iterator toIterator(final Enumeration e){\n" +
                "  return (new Iterator() {\n" +
                "    public boolean hasNext() {\n" +
                "      return e.hasMoreElements();}\n" +
                "    public Object next() {\n" +
                "      return e.nextElement();}\n" +
                "    public void remove() {}\n" +
                "  });\n" +
                "}"
        );