blob: 2305910cab23dea2d7e13bfafd2a76037c1e4294 [file] [log] [blame]
// Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
/**
* Code for converting HTML into text, for use during code generation of
* analyzer and analysis server.
*/
import 'package:analysis_tool/tools.dart';
import 'package:html/dom.dart' as dom;
final RegExp whitespace = new RegExp(r'\s');
/**
* Convert the HTML in [desc] into text, word wrapping at width [width].
*
* If [javadocStyle] is true, then the output is compatible with Javadoc,
* which understands certain HTML constructs.
*/
String nodesToText(List<dom.Node> desc, int width, bool javadocStyle,
{bool removeTrailingNewLine: false}) {
_TextFormatter formatter = new _TextFormatter(width, javadocStyle);
return formatter.collectCode(() {
formatter.addAll(desc);
formatter.lineBreak(false);
}, removeTrailingNewLine: removeTrailingNewLine);
}
/**
* Engine that transforms HTML to text. The input HTML is processed one
* character at a time, gathering characters into words and words into lines.
*/
class _TextFormatter extends CodeGenerator {
/**
* Word-wrapping width.
*/
final int width;
/**
* The word currently being gathered.
*/
String word = '';
/**
* The line currently being gathered.
*/
String line = '';
/**
* True if a blank line should be inserted before the next word.
*/
bool verticalSpaceNeeded = false;
/**
* True if no text has been output yet. This suppresses blank lines.
*/
bool atStart = true;
/**
* True if we are processing a <pre> element, thus whitespace should be
* preserved.
*/
bool preserveSpaces = false;
/**
* True if the output should be Javadoc compatible.
*/
final bool javadocStyle;
_TextFormatter(this.width, this.javadocStyle);
/**
* Process an HTML node.
*/
void add(dom.Node node) {
if (node is dom.Text) {
for (String char in node.text.split('')) {
if (preserveSpaces) {
wordBreak();
write(escape(char));
} else if (whitespace.hasMatch(char)) {
wordBreak();
} else {
resolveVerticalSpace();
word += escape(char);
}
}
} else if (node is dom.Element) {
switch (node.localName) {
case 'br':
lineBreak(false);
break;
case 'dl':
case 'dt':
case 'h1':
case 'h2':
case 'h3':
case 'h4':
case 'p':
lineBreak(true);
addAll(node.nodes);
lineBreak(true);
break;
case 'div':
lineBreak(false);
if (node.classes.contains('hangingIndent')) {
resolveVerticalSpace();
indentSpecial('', ' ', () {
addAll(node.nodes);
lineBreak(false);
});
} else {
addAll(node.nodes);
lineBreak(false);
}
break;
case 'ul':
lineBreak(false);
addAll(node.nodes);
lineBreak(false);
break;
case 'li':
lineBreak(false);
resolveVerticalSpace();
indentSpecial('- ', ' ', () {
addAll(node.nodes);
lineBreak(false);
});
break;
case 'dd':
lineBreak(true);
indent(() {
addAll(node.nodes);
lineBreak(true);
});
break;
case 'pre':
lineBreak(false);
resolveVerticalSpace();
if (javadocStyle) {
writeln('<pre>');
}
bool oldPreserveSpaces = preserveSpaces;
try {
preserveSpaces = true;
addAll(node.nodes);
} finally {
preserveSpaces = oldPreserveSpaces;
}
writeln();
if (javadocStyle) {
writeln('</pre>');
}
lineBreak(false);
break;
case 'a':
case 'b':
case 'body':
case 'html':
case 'i':
case 'span':
case 'tt':
addAll(node.nodes);
break;
case 'head':
break;
default:
throw new Exception('Unexpected HTML element: ${node.localName}');
}
} else {
throw new Exception('Unexpected HTML: $node');
}
}
/**
* Process a list of HTML nodes.
*/
void addAll(List<dom.Node> nodes) {
for (dom.Node node in nodes) {
add(node);
}
}
/**
* Escape the given character for HTML.
*/
String escape(String char) {
if (javadocStyle) {
switch (char) {
case '<':
return '&lt;';
case '>':
return '&gt;';
case '&':
return '&amp;';
}
}
return char;
}
/**
* Terminate the current word and/or line, if either is in progress.
*/
void lineBreak(bool gap) {
wordBreak();
if (line.isNotEmpty) {
writeln(line);
line = '';
}
if (gap && !atStart) {
verticalSpaceNeeded = true;
}
}
/**
* Insert vertical space if necessary.
*/
void resolveVerticalSpace() {
if (verticalSpaceNeeded) {
writeln();
verticalSpaceNeeded = false;
}
}
/**
* Terminate the current word, if a word is in progress.
*/
void wordBreak() {
if (word.isNotEmpty) {
atStart = false;
if (line.isNotEmpty) {
if (indentWidth + line.length + 1 + word.length <= width) {
line += ' $word';
} else {
writeln(line);
line = word;
}
} else {
line = word;
}
word = '';
}
}
}