Parsing XML and TXT files in PHP - php

Question

I have a Text.xml file with some text and the bibliographic references in this text. Its look like this:
Text.xml
<p>…blabla S.King (1987). Bla bla bla J.Doe (2001) blabla bla J.Martin (1995) blabla…</p>
And I have a Reference.txt file with list of bibliographic references and ID number for each reference. Its look like this:
Reference.txt
b1#S.King (1987)
b2#J.Doe (2001)
b3#J.Martin (1995)
I would like to find all bibliographic references from Reference.txt into Text.xml and then add a tag with ID. The goal is TextWithReference.xml who must look like this:
TextWithReference.xml
<p>…blabla <ref type="biblio" target=“b1”>S.King (1987)</ref>. Bla bla bla <ref type="biblio" target=“b2”>J.Doe (2001)</ref> blabla bla <ref type="biblio" target=“b3”>J.Martin (1995)</ref> blabla…</p>
To do this, I use a php file.
Search&Replace.php
<?php
$handle = fopen("Reference.txt","r");
while(!feof($handle))
{
$ligne = fgets($handle,1024);
$tabRef[] = $ligne;
}
fclose($handle);
$handleXML = fopen("Text.xml","r");
$fp = fopen("TextWithReference.xml", "w");
while(!feof($handleXML))
{
$ligneXML = fgets($handleXML,2048);
for($i=0;$i<sizeof($tabRef);$i++)
{
$tabSearch = explode('/#/',$tabRef[$i]);
$xmlID = $tabSearch[0];
$searchString = trim($tabSearch[1]);
if(preg_match('/$searchString/',$ligneXML))
{
$ligneXML = preg_replace('/($searchString)/','/<ref type=\"biblio\" target=\"#$xmlID\">\\0</ref>/',$ligneXML);
}
}
fwrite($fp, $ligneXML);
}
fclose($handleXML);
fclose($fp);
?>
The problem is that this php script just copy Text.xml in TextWithReference.xml without identifing the bibliographic references and without adding the tags…
Many thanks for your help!

Answer 1

There are a number of problems with your code.
The search strings contain characters that are special in regular expressions, such as parentheses. You need to escape these if you want to match them literally. The preg_quote function does this.
Your file-reading loops are not correct. while (!feof()) is not the correct way to read through a file, because the EOF flag isn't set until after you read at the end of the file. So you'll go through the loops an extra time. The proper way to write this is while ($ligne = fgets()).
You have single quotes around the strings where you're trying to substitute $searchString and $xmlID. Variables are only substituted inside double quotes. See What is the difference between single-quoted and double-quoted strings in PHP?
You don't need to put / delimiters around the replacement string in preg_replace.
It's inefficient to explode, trim and escape the lines from the Reference.txt every time you're processing a line in Text.xml. Do it once when you're reading Reference.txt.
In the replacement string, use $0 to replace with the matched text from the source. \0 is an obsolete method that isn't recommended.
You don't need parentheses around the search string in the regexp, since you're not using the $1 capture group in the replacement. And since it's around the whole regexp, it's the same as $0.
Here's the working rewrite:
<?php
$handle = fopen("Reference.txt","r");
$tabRef = array();
while($ligne = trim(fgets($handle,1024))) {
list($xmlID, $searchString) = explode('#', $ligne);
$tabRef[] = array($xmlID, preg_quote($searchString));
}
fclose($handle);
$handleXML = fopen("Text.xml","r");
$fp = fopen("TextWithReference.xml", "w");
while($ligneXML = fgets($handleXML,2048)) {
foreach ($tabRef as $tabSearch) {
$xmlID = $tabSearch[0];
$searchString = $tabSearch[1];
if(preg_match("/$searchString/",$ligneXML)) {
$ligneXML = preg_replace("/$searchString/","<ref type=\"biblio\" target=\"#$xmlID\">$0</ref>",$ligneXML);
}
}
fwrite($fp, $ligneXML);
}
fclose($handleXML);
fclose($fp);
?>
Another improvement takes advantage of the ability to give use arrays as the search and replacement arguments to preg_replace, instead of using a loop. When reading Reference.txt, create the regexp and replacement strings there, and put them each into an array.
<?php
$handle = fopen("Reference.txt","r");
$search = array();
$replacement = array();
while($ligne = trim(fgets($handle,1024))) {
list($xmlID, $searchString) = explode('#', $ligne);
$search[] = "/" . preg_quote($searchString) . "/";
$replacement[] = "<ref type=\"biblio\" target=\"#$xmlID\">$0</ref>";
}
fclose($handle);
$handleXML = fopen("Text.xml","r");
$fp = fopen("TextWithReference.xml", "w");
while($ligneXML = fgets($handleXML,2048)) {
$ligneXML = preg_replace($search,$replacement,$ligneXML);
fwrite($fp, $ligneXML);
}
fclose($handleXML);
fclose($fp);
?>