protected function parseUserValue($value)
{
$value = trim($value);
if ($value == '') {
//do not accept empty strings
$this->addError(wfMsgForContent('smw_emptystring'));
} else {
$parser = new ChemEqParser();
if ($parser->checkFormula($value) === true) {
$this->m_xsdValue = smwfXMLContentEncode($parser->getWikiFormat());
$this->m_html = $parser->getHtmlFormat();
if ($this->m_caption === false) {
$this->m_caption = $this->m_html;
}
$this->m_wikitext = $value;
} else {
$this->addError($value . ":" . $parser->getError() . "<br>");
}
if ($this->m_caption === false) {
$this->m_caption = $value;
}
}
return true;
}
/**
* Checks a chemical equation for syntactical correctness.
*
* Grammar for chemical equations:
* CE := CF [{'+'|'*'|'x'} CF]* [{'<-' | '<->' | '->' } CF [{'+'|'*'|'x'} CF]*]+
* CF is a chemical formula (see checkFormula())
*
* The fields <mError>, <mWikiFormat> and <mHtmlFormat> will be set.
*
* @param string $eq Wiki text of a chemical equation
* @return boolean <true> if the expression is a valid chemical equation,
* <false> otherwise
*/
public function checkEquation($eq)
{
$eq = trim(htmlspecialchars_decode($eq));
$formulaParser = new ChemEqParser();
try {
$result = $this->splitEquation($eq);
$wikiFormat = "";
$htmlFormat = "";
$delimCount = 0;
$delimiters = array('<-', '<->', '->', '+', '*', 'x');
foreach ($result as $term) {
$formulas = $this->splitChemTerm($term);
foreach ($formulas as $formula) {
if (in_array($formula, $delimiters)) {
$delimCount--;
}
switch ($formula) {
case "<-":
$htmlFormat .= ' ← ';
$wikiFormat .= $formula;
break;
case "->":
$htmlFormat .= ' → ';
$wikiFormat .= $formula;
break;
case "<->":
$htmlFormat .= ' ⇌ ';
$wikiFormat .= $formula;
break;
case "+":
$htmlFormat .= ' + ';
$wikiFormat .= $formula;
break;
case "*":
case "x":
$htmlFormat .= '●';
$wikiFormat .= "*";
break;
default:
if ($formulaParser->checkFormula($formula) === true) {
$delimCount++;
$wikiFormat .= $formulaParser->getWikiFormat();
$htmlFormat .= $formulaParser->getHtmlFormat();
} else {
throw new Exception($formulaParser->getError());
}
}
if ($delimCount < 0 || $delimCount > 1) {
throw new Exception(wfMsgForContent('smw_no_alternating_formula', $eq));
}
}
}
if ($delimCount != 1) {
// In the end, there must be one more formula than operators
throw new Exception(wfMsgForContent('smw_no_alternating_formula', $eq));
}
$this->mWikiFormat = $wikiFormat;
$this->mHtmlFormat = $htmlFormat;
$this->mError = "";
return true;
} catch (Exception $e) {
$this->mWikiFormat = "";
$this->mHtmlFormat = "";
$this->mError = $e->getMessage();
return false;
}
}