package com.twitter;
import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
import java.util.List;
/**
* A class for adding HTML highlighting in Tweet text (such as would be returned
* from a Search)
*/
class HitHighlighter {
/**
* Default HTML tag for highlight hits
*/
private static final String DEFAULT_HIGHLIGHT_TAG = "em";
/**
* the current HTML tag used for hit highlighting
*/
private String highlightTag;
/**
* Create a new HitHighlighter object.
*/
public HitHighlighter() {
highlightTag = DEFAULT_HIGHLIGHT_TAG;
}
/**
* Surround the <code>hits</code> in the provided <code>text</code> with an
* HTML tag. This is used with offsets from the search API to support the
* highlighting of query terms.
*
* @param text of the Tweet to highlight
* @param hits A List of highlighting offsets (themselves lists of two
* elements)
* @return text with highlight HTML added
*/
public String highlight(String text, List<List<Integer>> hits) {
if (hits == null || hits.isEmpty()) {
return (text);
}
StringBuilder sb = new StringBuilder(text.length());
CharacterIterator iterator = new StringCharacterIterator(text);
boolean isCounting = true;
boolean tagOpened = false;
int currentIndex = 0;
char currentChar = iterator.first();
while (currentChar != CharacterIterator.DONE) {
// TODO: this is slow.
for (List<Integer> start_end : hits) {
if (start_end.get(0) == currentIndex) {
sb.append(tag(false));
tagOpened = true;
} else if (start_end.get(1) == currentIndex) {
sb.append(tag(true));
tagOpened = false;
}
}
if (currentChar == '<') {
isCounting = false;
} else if (currentChar == '>' && !isCounting) {
isCounting = true;
}
if (isCounting) {
currentIndex++;
}
sb.append(currentChar);
currentChar = iterator.next();
}
if (tagOpened) {
sb.append(tag(true));
}
return (sb.toString());
}
/**
* Format the current <code>highlightTag</code> by adding < and >. If
* <code>closeTag</code> is <code>true</code> then the tag returned will
* include a <code>/</code> to signify a closing tag.
*
* @param true if this is a closing tag, false otherwise
*/
String tag(boolean closeTag) {
StringBuilder sb = new StringBuilder(highlightTag.length() + 3);
sb.append("<");
if (closeTag) {
sb.append("/");
}
sb.append(highlightTag).append(">");
return (sb.toString());
}
/**
* Get the current HTML tag used for phrase highlighting.
*
* @return current HTML tag (without < or >)
*/
public String getHighlightTag() {
return highlightTag;
}
/**
* Set the current HTML tag used for phrase highlighting.
*
* @param new HTML tag (without < or >)
*/
public void setHighlightTag(String highlightTag) {
this.highlightTag = highlightTag;
}
}