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124 lines
4.0 KiB
124 lines
4.0 KiB
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import java.util.Arrays;
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import java.util.HashSet;
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import java.util.LinkedList;
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import java.util.Queue;
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import java.util.Set;
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/*
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* SD2x Homework #2
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* This class represents a single HTML tag.
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* Please do not change this code! Your solution will be evaluated using this version of the class.
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*/
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public class HtmlTag {
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protected final String element;
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protected final boolean openTag;
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public HtmlTag(String element, boolean isOpenTag) {
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this.element = element.toLowerCase();
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openTag = isOpenTag;
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}
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public String getElement() {
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return element;
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}
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public boolean isOpenTag() {
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return openTag && !isSelfClosing();
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}
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public boolean matches(HtmlTag other) {
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return other != null
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&& element.equalsIgnoreCase(other.element)
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&& openTag != other.openTag;
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}
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public boolean isSelfClosing() {
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return SELF_CLOSING_TAGS.contains(element);
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}
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public boolean equals(Object obj) {
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if (obj instanceof HtmlTag) {
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HtmlTag other = (HtmlTag) obj;
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return element.equals(other.element)
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&& openTag == other.openTag;
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}
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return false;
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}
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public String toString() {
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return "<" + (openTag ? "" : "/")
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+ (element.equals("!--") ? "!-- --" : element) + ">";
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}
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/**
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* The remaining fields and functions are related to HTML file parsing.
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*/
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// a set of tags that don't need to be matched (self-closing)
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protected static final Set<String> SELF_CLOSING_TAGS = new HashSet<String>(
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Arrays.asList("!doctype", "!--", "?xml", "xml", "area", "base",
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"basefont", "br", "col", "frame", "hr", "img",
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"input", "link", "meta", "param"));
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protected static final String WHITESPACE = " \f\n\r\t";
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public static Queue<HtmlTag> tokenize(String text) {
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StringBuffer buf = new StringBuffer(text);
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Queue<HtmlTag> queue = new LinkedList<HtmlTag>();
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HtmlTag nextTag = nextTag(buf);
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while (nextTag != null) {
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queue.add(nextTag);
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nextTag = nextTag(buf);
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}
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return queue;
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}
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protected static HtmlTag nextTag(StringBuffer buf) {
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int openBracket = buf.indexOf("<");
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int closeBracket = buf.indexOf(">");
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if (openBracket >= 0 && closeBracket > openBracket) {
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// check for HTML comments: <!-- -->
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int commentIndex = openBracket + 4;
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if (commentIndex <= buf.length()
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&& buf.substring(openBracket + 1, commentIndex).equals("!--")) {
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// look for closing comment tag -->
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closeBracket = buf.indexOf("-->", commentIndex);
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if (closeBracket < 0) {
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return null;
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} else {
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buf.insert(commentIndex, " ");
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closeBracket += 3; // advance to the closing bracket >
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}
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}
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String element = buf.substring(openBracket + 1, closeBracket).trim();
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// remove attributes
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for (int i = 0; i < WHITESPACE.length(); i++) {
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int attributeIndex = element.indexOf(WHITESPACE.charAt(i));
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if (attributeIndex >= 0) {
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element = element.substring(0, attributeIndex);
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}
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}
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// determine whether opening or closing tag
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boolean isOpenTag = true;
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int checkForClosing = element.indexOf("/");
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if (checkForClosing == 0) {
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isOpenTag = false;
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element = element.substring(1);
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}
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element = element.replaceAll("[^a-zA-Z0-9!-]+", "");
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buf.delete(0, closeBracket + 1);
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return new HtmlTag(element, isOpenTag);
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} else {
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return null;
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}
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}
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}
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