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#include "nsParserUtils.h"
#include "nsIParser.h" // for kQuote et. al.
#include "jsapi.h"

// This method starts at aOffSet in aStr and tries to find aChar. It keeps 
// skipping whitespace till it finds aChar or some other non-whitespace character.  If
// it finds aChar, it returns aChar's offset.  If it finds some other non-whitespace character
// or runs into the end of the string, it returns -1.
static PRInt32
FindWhileSkippingWhitespace(nsString& aStr, PRUnichar aChar, PRInt32 aOffset)
{
  PRInt32 i = aOffset;
  PRUnichar ch = aStr.CharAt(i);
  PRInt32 index = -1;

  while (ch == '\n' || ch == '\t' || ch == '\r') {
    ch = aStr.CharAt(++i);
  }

  if (ch == aChar)
    index = i;

  return index;
}


nsresult
nsParserUtils::GetQuotedAttributeValue(nsString& aSource,
                                       const nsAFlatString& aAttribute,
                                       nsString& aValue)
{  
  PRInt32 startOfAttribute = 0;     // Index into aSource where the attribute name starts
  PRInt32 startOfValue = 0;         // Index into aSource where the attribute value starts
  PRInt32 posnOfValueDelimiter = 0; 
  nsresult result = NS_ERROR_FAILURE;

  // While there are more characters to look at
  while (startOfAttribute != -1) {
    // Find the attribute starting at offset
    startOfAttribute = aSource.Find(aAttribute.get(), PR_FALSE, startOfAttribute);
    // If attribute found
    if (startOfAttribute != -1) { 
      // Find the '=' character while skipping whitespace
      startOfValue = FindWhileSkippingWhitespace(aSource, '=', startOfAttribute + aAttribute.Length());
      // If '=' found
      if (startOfValue != -1) {
        PRUnichar delimiter = kQuote;
        // Find the quote or apostrophe while skipping whitespace
        posnOfValueDelimiter = FindWhileSkippingWhitespace(aSource, kQuote, startOfValue + 1);
        if (posnOfValueDelimiter == -1) {
          posnOfValueDelimiter = FindWhileSkippingWhitespace(aSource, kApostrophe, startOfValue + 1);
          delimiter = kApostrophe;
        }
        // If quote or apostrophe found
        if (posnOfValueDelimiter != -1) {
          startOfValue = posnOfValueDelimiter + 1;
          // Find the ending quote or apostrophe
          posnOfValueDelimiter = aSource.FindChar(delimiter, PR_FALSE, startOfValue);
          // If found
          if (posnOfValueDelimiter != -1) {
            // Set the value of the attibute and exit the loop
            // The attribute value starts at startOfValue and ends at (posnOfValueDelimiter - 1)
            aSource.Mid(aValue, startOfValue, posnOfValueDelimiter - startOfValue);
            result = NS_OK;
            break;
          }
          else {
            // Try to find the attribute in the remainder of the string
            startOfAttribute++;
            continue;
          } // Endif found  
        }
        else {
          // Try to find the attribute in the remainder of the string
          startOfAttribute++;
          continue;
        } // Endif quote or apostrophe found
      } 
      else {
        // Try to find the attribute in the remainder of the string
        startOfAttribute++;
        continue;
      } // Endif '=' found
    } // Endif attribute found
  } // End while
  
  return result;
}


// XXX Stolen from nsHTMLContentSink. Needs to be shared.
// XXXbe share also with nsRDFParserUtils.cpp and nsHTMLContentSink.cpp
// Returns PR_TRUE if the language name is a version of JavaScript and
// PR_FALSE otherwise
PRBool
nsParserUtils::IsJavaScriptLanguage(const nsString& aName, const char* *aVersion)
{
  JSVersion version = JSVERSION_UNKNOWN;

  if (aName.EqualsIgnoreCase("JavaScript") ||
      aName.EqualsIgnoreCase("LiveScript") ||
      aName.EqualsIgnoreCase("Mocha")) {
    version = JSVERSION_DEFAULT;
  }
  else if (aName.EqualsIgnoreCase("JavaScript1.0")) {
    version = JSVERSION_1_0;
  }
  else if (aName.EqualsIgnoreCase("JavaScript1.1")) {
    version = JSVERSION_1_1;
  }
  else if (aName.EqualsIgnoreCase("JavaScript1.2")) {
    version = JSVERSION_1_2;
  }
  else if (aName.EqualsIgnoreCase("JavaScript1.3")) {
    version = JSVERSION_1_3;
  }
  else if (aName.EqualsIgnoreCase("JavaScript1.4")) {
    version = JSVERSION_1_4;
  }
  else if (aName.EqualsIgnoreCase("JavaScript1.5")) {
    version = JSVERSION_1_5;
  }
  if (version == JSVERSION_UNKNOWN)
    return PR_FALSE;
  *aVersion = JS_VersionToString(version);
  return PR_TRUE;
}