title: BigQuery REGEXP_MATCH and accents : boundary wildcard fails?
body: <p>In GAS I can correctly match accents with regular expression having boundary characters, such as \bà\b. The character à is matched only when it is a separate word. This works in GAS: </p>
  
  <pre><code>function test_regExp() {
    var str = "la séance est à Paris";
    var RegExp = "\\bà\\b";
    var PatReg= new RegExp( RegExp);
    var found=PatReg.exec(str);
    if (found) {
      Logger.log( [str.substring(0,found.index),found[0],str.substring(found[0].length+found.index)] );
    } else Logger.log("oops! Did not match");
  </code></pre>
  
  <p>In BigQuery, if boundary characters are next to accents the patterns do not match. \bséance\b matches séance: </p>
  
  <pre><code>SELECT [row],etext,ftext FROM [hcd.hdctextx] WHERE (REGEXP_MATCH(ftext,"\\bséance\\b") ) LIMIT 100;
  </code></pre>
  
  <p>\bà\b does not match à as a word: </p>
  
  <pre><code>SELECT [row],etext,ftext FROM [hcd.hdctextx] WHERE (REGEXP_MATCH(ftext,"\\bà\\b") ) LIMIT 100;
  </code></pre>
  
  <p>I'm assuming that BigQuery, unlike GAS, is including accents in the boundary character set. So \bséance\b works because é can function properly as a boundary in that configuration. \bà\b or \bétranger\b or \bmarché\b do not work because accent + \b is interpreted as \b\b, which never matches anything. (Ok, I'm grasping at straws here, because I can't find a better explanation....besides a bug.)</p>
  
  <p>I don't think it is a unicode problem, because it only crops up at boundary positions. </p>
  
  <p>For the moment therefore, no way to use boundary in those particular configurations of accents.</p>
  
  <p>Is there a way to set the Locale in BigQuery or other fix? </p>
  
  <p>Workaround: substitute (?:[^a-zA-Zéàïëâê]) and so on for \b.</p>
  
  <p>Thanks! </p>