/* Filename:  stringhelp.cpp

   Author:  Br. David Carlson

   Date:  January 25, 2001

   This header file, together with the matching stringhelp.h file,
   provides StrMax, StringType, and these operations on StringType
   data: Capitalize, MyGetline, SubstringPresent, GetSubstring and
   GetValue.
*/

#include "stringhelp.h"


/* Given:  String       A string to capitalize.
   Task:   To capitalize all letters in String.
   Return: NewString    The capitalized verson of the string.
*/
void Capitalize(StringType String, StringType NewString)
   {
   int k, Len;

   Len = strlen(String);

   for (k = 0; k < Len; k++)
      NewString[k] = toupper(String[k]);

   NewString[Len] = '\0';
   }


/* Given:  String       A string to search.
           Substring    The substring to search for.
   Task:   To see if Substring occurs within String. A case-insenstive
           check is made.  (For example, "aBc" is present in "dabCq".)
   Return: True if Substring is present within String, false otherwise.
*/
bool SubstringPresent(StringType String, StringType Substring)
   {
   StringType CapString, CapSubstring;

   Capitalize(String, CapString);
   Capitalize(Substring, CapSubstring);
   if (strstr(CapString, CapSubstring) == '\0')
      return false;
   else
      return true;
   }


/* Given:  String       The string to search through.
           StartChar    The character preceding the sought for substring.
           EndChar      The character immediately following the substring.
   Task:   To extract the substring of String found between the first
           occurance of StartChar and the first occurance of EndChar after
           StartChar.
   Return: Substring    This substring.
           True in the function name if such a substring was found.
           False in the function name if no such substring was found (in
           which case Substring may contain garbage).
*/
bool GetSubstring(StringType String, char StartChar, char EndChar,
   StringType Substring)
   {
   int k, m, Length;
   bool Flag;

   Length = strlen(String);
   Flag = false;

   for (k = 0; k < Length; k++)
      if (String[k] == StartChar)
         {
         Flag = true;
         break;
         }

   if (! Flag)
      return false;

   k++;
   m = 0;
   Flag = false;
   while (k < Length)
      {
      if (String[k] == EndChar)
         {
         Flag = true;
         Substring[m] = '\0';
         break;
         }
      else
         Substring[m++] = String[k++];
      }

   return Flag;
   }


/* Given:  InStream     An input file stream already open for reading.
           StringMax    The maximum number of characters that can be put
                        into String, including the NULL that marks the
                        end of the string.
   Task:   To read up to StringMax - 1 characters from InStream, storing
           them in String, but stopping if a newline is read or end of
           file or an error condition is reached.
   Return: String       The string just read, with a NULL appended to
                        mark the end of the string.  If a newline was
                        read, it is not stored in String.
           Also returns in the function name the count of the number of
           characters placed in String (not including the NULL).
*/
int MyGetLine(istream & InStream, char * String, int StringMax)
   {
   char Ch;
   int Count, Last;

   Count = 0;
   Last = StringMax - 1;
   Ch = InStream.get();

   while ((Ch != '\n') && (! InStream.fail()))
      {
      if (Count < Last)
         String[Count++] = Ch;
      Ch = InStream.get();
      }

   String[Count] = '\0';
   return Count;
   }


/* Given:  EnvVariable   The name (as a string) of a WWW environment variable.
   Task:   To retrieve the value of this variable, being sure not to copy more
           characters than will fit into Result and rejecting any dangerous
           characters (anything other than alphanumeric characters, NULL,
           space, plus sign, minus sign, and period).
   Return: Result        The value of this WWW environment variable, truncated
                         if need be.  If a dangerous character is found, the
                         empty string is returned in Result.
*/
void GetValue(StringType EnvVariable, StringType Result)
   {
   char * Match;
   char ch;
   register int k;

   Match = getenv(EnvVariable);

   for (k = 0; k < StrMax - 1; k++)
      {
      ch = *Match;
      if (ch == '\0')
         {
         Result[k] = '\0';
         break;
         }
      else if (isalnum(ch) || (ch == ' ') || (ch == '+') || (ch == '-')
         || (ch == '.'))
         {
         Result[k] = ch;
         Match++;
         }
      else   // bad data, return empty string
         {
         Result[0] = '\0';
         break;
         }
      }

   // just to be sure there's a NULL at the end of the string:
   Result[StrMax - 1] = '\0'; 
   }