/* 
   scanFloat.def

   Copyright (C) 1995, 1996 Ovidiu Predescu and Mircea Oancea.
   All rights reserved.

   Author: Ovidiu Predescu <ovidiu@bx.logicnet.ro>

   This file is part of libFoundation.

   Permission to use, copy, modify, and distribute this software and its
   documentation for any purpose and without fee is hereby granted, provided
   that the above copyright notice appear in all copies and that both that
   copyright notice and this permission notice appear in supporting
   documentation.

   We disclaim all warranties with regard to this software, including all
   implied warranties of merchantability and fitness, in no event shall
   we be liable for any special, indirect or consequential damages or any
   damages whatsoever resulting from loss of use, data or profits, whether in
   an action of contract, negligence or other tortious action, arising out of
   or in connection with the use or performance of this software.
*/

/* This file is included by NSScanner.m to produce the definitions of
   -scanFloat: and -scanDouble: methods. In order to work, either FLOAT_TYPE or
   DOUBLE_TYPE should be defined. */

#if defined(FLOAT_TYPE)
# define TYPE double
# define MIN_VALUE FLT_MIN
# define MAX_VALUE FLT_MAX
# define MAX_DIG FLT_DIG
# define MAX_EXP FLT_MAX_10_EXP
# define MIN_EXP FLT_MIN_10_EXP
#elif defined(DOUBLE_TYPE)
# define TYPE double
# define MIN_VALUE DBL_MIN
# define MAX_VALUE DBL_MAX
# define MAX_DIG DBL_DIG
# define MAX_EXP DBL_MAX_10_EXP
# define MIN_EXP DBL_MIN_10_EXP
#else
# error You should define FLOAT_TYPE or DOUBLE_TYPE
#endif

    NSCharacterSet* decimals = nil;
    id string = [self string];
    unsigned int orig;
    unsigned int location;
    unsigned int length = [string length];
    TYPE maxvalue = MAX_VALUE / 10;
    TYPE mantissa = 0;
    TYPE decValue = 0;
    TYPE exponent1 = 0;
    TYPE result;
    int exponent2 = 0;
    BOOL isNegative = NO;
    NSDictionary* locale = [self locale];
    unichar zeroChar = '0';
    unichar thousandSep = ',';
    unichar decimalSep = '.';
    unichar c;

    if ([self isAtEnd])
	return NO;

    /* First skip the blank characters */
    [self scanCharactersFromSet:[self charactersToBeSkipped] intoString:NULL];

    /* Create the decimals set */
    if (locale) {
	NSString* thousandString = [locale objectForKey:NSThousandsSeparator];
	NSString* decimalsString = [locale objectForKey:NSDecimalDigits];
	NSString* decimalSepString = [locale objectForKey:NSDecimalSeparator];

	if (decimalsString) {
	    zeroChar = [decimalsString characterAtIndex:0];
	    decimals = [NSCharacterSet characterSetWithCharactersInString:
				    decimalsString];
	}

	if (thousandString)
	    thousandSep = [thousandString characterAtIndex:0];

	if (decimalSepString)
	    decimalSep = [decimalSepString characterAtIndex:0];
    }

    if (!decimals)
	decimals = [NSCharacterSet decimalDigitCharacterSet];

    orig = [self scanLocation];
    c = [string characterAtIndex:orig];
    if (c == '-' || c == '+') {
	isNegative = (c == '-');
	orig++;
    }

    /* Scan the mantisa */
    for (location = orig; location < length; location++) {
	c = [string characterAtIndex:location];
	if ([decimals characterIsMember:c]) {
	    /* Even if result is greater than the maximum value that can be 
	       represented, continue the scanning to skip the hole number. */
	    if (mantissa <= maxvalue)
		mantissa = mantissa * 10 + (c - zeroChar);
	    continue;
	}
	if (c == thousandSep)
	    continue;

	/* If `c' is neither a decimal nor a thousand separator, break. */
	break;
    }
    result = mantissa;

    if (c == decimalSep) {
	/* The number has a decimal part. Store it in the decValue but no more
	   than MAX_DIG digits; then skip all the digits. */
	int digits_no = 0;

	location++;

	/* Iterate through the exponent's digits */
	for (exponent1 = 0.1; location < length; location++, exponent1 /= 10) {
	    c = [string characterAtIndex:location];

	    /* Break if the character is not a digit */
	    if (![decimals characterIsMember:c])
		break;

	    /* If result is too big to be represented just skip to the
	       next character. */
	    if (result > maxvalue)
		continue;

	    digits_no++;

	    /* Only store the digit if the number of digits read so far is less
	       than MAX_DIG to avoid a possible overflow. */
	    if (digits_no <= MAX_DIG)
		decValue += (c - zeroChar) * exponent1;
	}
    }
    if (result <= maxvalue)
	result += decValue;

    if (c == 'e' || c == 'E') {
	/* The number has an exponent. Store it in exponent2. */
	BOOL expIsNegative = NO;

	location++;
	if (location < length) {
	    c = [string characterAtIndex:location];
	    if (c == '-') {
		expIsNegative = YES;
		location++;
	    }
	    else if (c == '+')
		location++;
	}

	/* Read the digits of the exponent. First skip the leading zeroes. */
	for (; location < length; location++) {
	    c = [string characterAtIndex:location];
	    if (c == '0')
		continue;
	    else
		break;
	}

	/* Read the exponent digits but check if it's greater than MAX_EXP or
	   less than MIN_EXP. */
	for (; location < length; location++) {
	    TYPE power10[10] = {
		1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9
	    };

	    c = [string characterAtIndex:location];

	    /* Break if the character is not a digit */
	    if (![decimals characterIsMember:c])
		break;

	    /* If result is too big to be represented just skip to the
	       next character. */
	    if (result > maxvalue)
		continue;

	    if (expIsNegative) {
		if (exponent2 < abs(MIN_EXP)) {
		    exponent2 = exponent2 * 10 + (c - zeroChar);
		    /* Adjust the result */
		    if (exponent2 < abs(MIN_EXP))
			result /= power10[c - zeroChar];
		}
	    }
	    else {
		if (exponent2 < MAX_EXP) {
		    exponent2 = exponent2 * 10 + (c - zeroChar);
		    /* Adjust the result */
		    if (exponent2 < MAX_EXP)
			result *= power10[c - zeroChar];
		}
	    }
	}
    }

    if (location != orig) {
	[self setScanLocation:location];

	if (result > maxvalue) {
	    if (value)
		*value = (isNegative ? MIN_VALUE : MAX_VALUE);
	    return NO;
	}
	else {
	    if (value)
		*value = (isNegative ? -result : result);
	    return YES;
	}
    }

    return NO;

#undef TYPE
#undef MIN_VALUE
#undef MAX_VALUE
#undef MAX_DIG
#undef MAX_EXP
#undef MIN_EXP