libs-base/Source/NSScanner.m

/* Implemenation of NSScanner class
   Copyright (C) 1996 Free Software Foundation, Inc.

   Author:  Eric Norum <eric@skatter.usask.ca>
   Date: 1996
   
   This file is part of the GNUstep Objective-C Library.

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.
   
   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with this library; if not, write to the Free
   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/ 

#include <Foundation/NSScanner.h>
#include <Foundation/NSException.h>
#include <float.h>
#include <limits.h>
#include <math.h>
#include <ctype.h>    /* FIXME: May go away once I figure out Unicode */

/*
 * Cache the default NSCharacterSet of characters to be skipped.
 * FIXME: This would be unecessary if NSCharacterSet did the caching.
 */
static NSCharacterSet *defaultCharactersToBeSkipped;

@implementation NSScanner

/*
 * Class initialization.
 * Fill in default NSCharacterSet of characters to be skipped.
 */
+ (void)initialize
{
  if (defaultCharactersToBeSkipped == nil)
    defaultCharactersToBeSkipped = 
      [[NSCharacterSet whitespaceAndNewlineCharacterSet] retain];
}

/*
 * Create and return a scanner that scans aString.
 */
+ scannerWithString:(NSString *)aString
{
  return [[[self alloc] initWithString: aString]
	   autorelease];
}

+ localizedScannerWithString: (NSString*)locale
{
  [self notImplemented: _cmd];
  return Nil;
}

/*
 * Initialize a a newly-allocated scanner to scan aString.
 * Returns self.
 */
- initWithString:(NSString *)aString
{
  [super init];
  string = [aString copyWithZone: [self zone]];
  len = [string length];
  charactersToBeSkipped = defaultCharactersToBeSkipped;
  return self;
}

/*
 * Deallocate a scanner and all its associated storage.
 */
- (void)dealloc
{
  [string release];
  [locale release];
  if (charactersToBeSkipped != defaultCharactersToBeSkipped)
    [charactersToBeSkipped release];
  [super dealloc];
}

/*
 * Like scanCharactersFromSet:intoString: but no initial skip
 * For internal use only.
 */
- (BOOL)_scanCharactersFromSet: (NSCharacterSet *)set
		    intoString: (NSString **)value;
{
  unsigned int start;

  if (scanLocation >= len)
    return NO;
  start = scanLocation;
  while (scanLocation < len)
    {
      if (![set characterIsMember: [string characterAtIndex:scanLocation]])
	break;
      scanLocation++;
    }
  if (scanLocation == start)
    return NO;
  if (value)
    {
      NSRange range;
      range.location = start;
      range.length = scanLocation - start;
      *value = [string substringFromRange: range];
    }
  return YES;
}

/*
 * Scan characters to be skipped.
 * Return YES if there are more characters to be scanned.
 * Return NO if the end of the string is reached.
 * For internal use only.
 */
- (BOOL) _skipToNextField
{
  [self _scanCharactersFromSet: charactersToBeSkipped intoString: NULL];
  if (scanLocation >= len)
    return NO;
  return YES;
}

/*
 * Returns YES if no more characters remain to be scanned.
 * Returns YES if all characters remaining to be scanned are to be skipped.
 * Returns NO if there are characters left to scan.
 */
- (BOOL) isAtEnd
{
  unsigned int save_scanLocation;
  BOOL ret;

  if (scanLocation >= len)
    return YES;
  save_scanLocation = scanLocation;
  ret = ![self _skipToNextField];
  scanLocation = save_scanLocation;
  return ret;
}

/*
 * Internal version of scanInt: method.
 * Does the actual work for scanInt: except for the initial skip.
 * For internal use only.  This method may move the scan location
 * even if a valid integer is not scanned.
 * Based on the strtol code from the GNU C library.  A little simpler since
 * we deal only with base 10.
 * FIXME: I don't use the decimalDigitCharacterSet here since it
 * includes many more characters than the ASCII digits.  I don't
 * know how to convert those other characters, so I ignore them
 * for now.  For the same reason, I don't try to support all the
 * possible Unicode plus and minus characters.
 */
- (BOOL) _scanInt: (int*)value
{
  unsigned int num = 0;
  const unsigned int limit = UINT_MAX / 10;
  BOOL negative = NO;
  BOOL overflow = NO;
  BOOL got_digits = NO;

  /* Check for sign */
  switch ([string characterAtIndex:scanLocation])
    {
    case '+':
      scanLocation++;
      break;
    case '-':
      negative = YES;
      scanLocation++;
      break;
    }

  /* Process digits */
  while (scanLocation < len)
    {
      unichar digit = [string characterAtIndex: scanLocation];
      if ((digit < '0') || (digit > '9'))
	break;
      if (!overflow) {
	if (num >= limit)
	  overflow = YES;
	else
	  num = num * 10 + (digit - '0');
      }
      scanLocation++;
      got_digits = YES;
    }

  /* Save result */
  if (!got_digits)
    return NO;
  if (value)
    {
      if (num > (negative ? -(unsigned int)INT_MIN : (unsigned int)INT_MAX))
	overflow = YES;
      if (overflow)
	num = negative ? INT_MIN: INT_MAX;
      if (negative)
	*value = -num;
      else
	*value = num;
    }
  return YES;
}

/*
 * Scan an int into value.
 */
- (BOOL) scanInt: (int*)value
{
  unsigned int saveScanLocation = scanLocation;

  if ([self _skipToNextField] && [self _scanInt: value])
    return YES;
  scanLocation = saveScanLocation;
  return NO;
}

/*
 * Scan a long long int into value.
 * Same as scanInt, except with different variable types and limits.
 */
- (BOOL)scanLongLong: (long long *)value
{
#if defined(LONG_LONG_MAX)
  unsigned long long num = 0;
  const unsigned long long limit = ULONG_LONG_MAX / 10;
  BOOL negative = NO;
  BOOL overflow = NO;
  BOOL got_digits = NO;
  unsigned int saveScanLocation = scanLocation;

  /* Skip whitespace */
  if (![self _skipToNextField])
    {
      scanLocation = saveScanLocation;
      return NO;
    }

  /* Check for sign */
  switch ([string characterAtIndex:scanLocation])
    {
    case '+':
      scanLocation++;
      break;
    case '-':
      negative = YES;
      scanLocation++;
      break;
    }

    /* Process digits */
  while (scanLocation < len)
    {
      unichar digit = [string characterAtIndex:scanLocation];
      if ((digit < '0') || (digit > '9'))
	break;
      if (!overflow) {
	if (num >= limit)
	  overflow = YES;
	else
	  num = num * 10 + (digit - '0');
      }
      scanLocation++;
      got_digits = YES;
    }

    /* Save result */
  if (!got_digits)
    {
      scanLocation = saveScanLocation;
      return NO;
    }
  if (value)
    {
      if (num > (unsigned long long)LONG_LONG_MAX)
	/* xxx When would this ever be true?  Isn't is impossible? mccallum. */
	overflow = YES;
      if (overflow)
	num = negative ? LONG_LONG_MIN: LONG_LONG_MAX;
      if (negative)
	*value = -num;
      else
	*value = num;
    }
  return YES;
#else /* defined(LONG_LONG_MAX) */
  /*
   * Provide compile-time warning and run-time exception.
   */
#    warning "Can't use long long variables."
  [NSException raise: NSGenericException
	       format:@"Can't use long long variables."];
  return NO;
#endif /* defined(LONG_LONG_MAX) */
}

/*
 * Scan a double into value.
 * Returns YES if a valid floating-point expression was scanned. 
 * Returns NO otherwise.
 * On overflow, HUGE_VAL or -HUGE_VAL is put into value and YES is returned.
 * On underflow, 0.0 is put into value and YES is returned.
 * Based on the strtod code from the GNU C library.
 */
- (BOOL)scanDouble:(double *)value
{
  unichar decimal;
  unichar c = 0;
  double num = 0.0;
  long int exponent = 0;
  BOOL negative = NO;
  BOOL got_dot = NO;
  BOOL got_digit = NO;
  unsigned int saveScanLocation = scanLocation;

  /* Skip whitespace */
  if (![self _skipToNextField])
    {
      scanLocation = saveScanLocation;
      return NO;
    }

  /*
   * FIXME: Should get decimal point character from locale.  The problem
   * is that I can't find anything in the OPENSTEP specification about
   * the format of the locale dictionary.
   */
  decimal = '.';

  /* Check for sign */
  switch ([string characterAtIndex:scanLocation])
    {
    case '+':
      scanLocation++;
      break;
    case '-':
      negative = YES;
      scanLocation++;
      break;
    }

    /* Process number */
  while (scanLocation < len)
    {
      c = [string characterAtIndex: scanLocation];
      if ((c >= '0') && (c <= '9'))
	{
	  /* Ensure that the number being accumulated will not overflow. */
	  if (num >= (DBL_MAX / 10.000000001))
	    {
	      ++exponent;
	    }
	  else
	    {
	      num = (num * 10.0) + (c - '0');
	      got_digit = YES;
	    }
            /* Keep track of the number of digits after the decimal point.
	       If we just divided by 10 here, we would lose precision. */
	  if (got_dot)
	    --exponent;
        }
      else if (!got_dot && (c == decimal))
	{
	  /* Note that we have found the decimal point. */
	  got_dot = YES;
        }
      else
	{
	  /* Any other character terminates the number. */
	  break;
        }
      scanLocation++;
    }
    if (!got_digit)
      {
	scanLocation = saveScanLocation;
        return NO;
      }

    /* Check for trailing exponent
       Numbers like 1.23eFOO are rejected. */
    if ((scanLocation < len) && ((c == 'e') || (c == 'E')))
      {
        int exp;
        scanLocation++;
        if (![self _scanInt: &exp])
	  {
	    scanLocation = saveScanLocation;
	    return NO;
	  }

	/* Check for exponent overflow */
	if (num)
	  {
	    if ((exponent > 0) && (exp > (LONG_MAX - exponent)))
	      exponent = LONG_MAX;
	    else if ((exponent < 0) && (exp < (LONG_MIN - exponent)))
	      exponent = LONG_MIN;
	    else
	      exponent += exp;
	  }
      }
    if (value)
      {
        if (num && exponent)
	  num *= pow(10.0, (double) exponent);
        if (negative)
	  *value = -num;
        else
	  *value = num;
      }
    return YES;
}

/*
 * Scan a float into value.
 * Returns YES if a valid floating-point expression was scanned. 
 * Returns NO otherwise.
 * On overflow, HUGE_VAL or -HUGE_VAL is put into value and YES is returned.
 * On underflow, 0.0 is put into value and YES is returned.
 */
- (BOOL)scanFloat: (float*)value
{
  double num;
  
  if (value == NULL)
    return [self scanDouble:NULL];
  if ([self scanDouble:&num])
    {
      *value = num;
      return YES;
    }
  return NO;
}
    
/*
 * Scan as long as characters from aSet are encountered.
 * Returns YES if any characters were scanned.
 * Returns NO if no characters were scanned.
 * If value is non-NULL, and any characters were scanned, a string
 * containing the scanned characters is returned by reference in value.
 */
- (BOOL)scanCharactersFromSet:(NSCharacterSet *)aSet 
		   intoString:(NSString **)value;
{
  unsigned int saveScanLocation = scanLocation;

  if ([self _skipToNextField]
      && [self _scanCharactersFromSet: aSet intoString: value])
    return YES;
  scanLocation = saveScanLocation;
  return NO;
}

/*
 * Scan until a character from aSet is encountered.
 * Returns YES if any characters were scanned.
 * Returns NO if no characters were scanned.
 * If value is non-NULL, and any characters were scanned, a string
 * containing the scanned characters is returned by reference in value.
 */
- (BOOL)scanUpToCharactersFromSet:(NSCharacterSet *)set 
		       intoString:(NSString **)value;
{
  unsigned int saveScanLocation = scanLocation;
  unsigned int start;

  if (![self _skipToNextField])
    return NO;
  start = scanLocation;
  while (scanLocation < len)
    {
      if ([set characterIsMember:[string characterAtIndex: scanLocation]])
	break;
      scanLocation++;
    }
  if (scanLocation == start)
    {
      scanLocation = saveScanLocation;
      return NO;
    }
  if (value)
    {
      NSRange range;
      range.location = start;
      range.length = scanLocation - start;
      *value = [string substringFromRange: range];
    }
  return YES;
}

/*
 * Scans for aString.
 * Returns YES if the characters at the scan location match aString.
 * Returns NO if the characters at the scan location do not match aString.
 * If the characters at the scan location match aString.
 * If value is non-NULL, and the characters at the scan location match aString,
 * a string containing the matching string is returned by reference in value.
 */
- (BOOL)scanString:(NSString *)aString intoString:(NSString **)value;
{
  NSRange range;
  unsigned int saveScanLocation = scanLocation;
    
  [self _skipToNextField];
  range.location = scanLocation;
  range.length = [aString length];
  range = [string rangeOfString:aString
		  options:caseSensitive ? 0 : NSCaseInsensitiveSearch
		  range:range];
  if (range.length == 0)
    {
      scanLocation = saveScanLocation;
      return NO;
    }
  if (value)
    *value = [string substringFromRange:range];
  scanLocation += range.length;
  return YES;
}

/*
 * Scans the string until aString is encountered..
 * Returns YES if any characters were scanned.
 * Returns NO if no characters were scanned.
 * If value is non-NULL, and any characters were scanned, a string
 * containing the scanned characters is returned by reference in value.
 */
- (BOOL)scanUpToString:(NSString *)aString 
	    intoString:(NSString **)value;
{
  NSRange range;
  NSRange found;
  unsigned int saveScanLocation = scanLocation;
    
  [self _skipToNextField];
  range.location = scanLocation;
  range.length = len - scanLocation;
  found = [string rangeOfString:aString
		  options:caseSensitive ? 0 : NSCaseInsensitiveSearch
		  range:range];
  if (found.length)
    range.length = found.location - scanLocation;
  if (range.length == 0)
    {
      scanLocation = saveScanLocation;
      return NO;
    }
  if (value)
    *value = [string substringFromRange:range];
  scanLocation += range.length;
  return YES;
}

/*
 * Returns the string being scanned.
 */
- (NSString *)string
{
  return string;
}

/*
 * Returns the character index at which the scanner
 * will begin the next scanning operation.
 */
- (unsigned)scanLocation
{
  return scanLocation;
}

/*
 * Set the character location at which the scanner
 * will begin the next scanning operation to anIndex.
 */
- (void)setScanLocation:(unsigned int)anIndex
{
  scanLocation = anIndex;
}

/*
 * Returns YES if the scanner makes a distinction
 * between upper and lower case characters.
 */
- (BOOL)caseSensitive
{
  return caseSensitive;
}

/*
 * If flag is YES the scanner will consider upper and lower case
 * to be the same during scanning.  If flag is NO the scanner will
 * not make a distinction between upper and lower case characters.
 */
- (void)setCaseSensitive:(BOOL)flag
{
  caseSensitive = flag;
}

/*
 * Return a character set object containing the characters the scanner
 * will ignore when searching for the next element to be scanned.
 */
- (NSCharacterSet *)charactersToBeSkipped
{
  return charactersToBeSkipped;
}

/*
 * Set the characters to be ignored when the scanner
 * searches for the next element to be scanned.
 */
- (void)setCharactersToBeSkipped:(NSCharacterSet *)aSet
{
  if (charactersToBeSkipped != defaultCharactersToBeSkipped)
    [charactersToBeSkipped release];
  charactersToBeSkipped = [aSet copyWithZone: [self zone]];
}

/*
 * Returns a dictionary object containing the locale
 * information used by the scanner.
 */
- (NSDictionary *)locale
{
  return locale;
}

/*
 * Set the dictionary containing the locale
 * information used by the scanner to localeDictionary.
 */
- (void)setLocale:(NSDictionary *)localeDictionary
{
  locale = [localeDictionary retain];
}

/*
 * NSCopying protocol
 */
- copyWithZone:(NSZone *)zone
{
  NSScanner *n = [[self class] allocWithZone:zone];

  [n initWithString: string];
  [n setCharactersToBeSkipped: charactersToBeSkipped];
  [n setLocale: locale];
  [n setScanLocation: scanLocation];
  [n setCaseSensitive: caseSensitive];
  return n;
}

- copy
{
  return [self copyWithZone: [self zone]];
}

@end