---

sprintf.c

Go to the documentation of this file.

/**********************************************************************

  sprintf.c -

  $Author: matz $
  $Date: 2004/12/08 06:22:51 $
  created at: Fri Oct 15 10:39:26 JST 1993

  Copyright (C) 1993-2003 Yukihiro Matsumoto
  Copyright (C) 2000  Network Applied Communication Laboratory, Inc.
  Copyright (C) 2000  Information-technology Promotion Agency, Japan

**********************************************************************/

#include "ruby.h"
#include <ctype.h>
#include <math.h>

#define BIT_DIGITS(N)   (((N)*146)/485 + 1)  /* log2(10) =~ 146/485 */

static void fmt_setup (char*,int,int,int,int);

static char*
remove_sign_bits(str, base)
    char *str;
    int base;
{
    char *s, *t;
    
    s = t = str;

    if (base == 16) {
        while (*t == 'f') {
            t++;
        }
    }
    else if (base == 8) {
        if (*t == '3') t++;
        while (*t == '7') {
            t++;
        }
    }
    else if (base == 2) {
        while (*t == '1') {
            t++;
        }
    }
    if (t > s) {
        while (*t) *s++ = *t++;
        *s = '\0';
    }

    return str;
}

static char
sign_bits(base, p)
    int base;
    const char *p;
{
    char c = '.';

    switch (base) {
      case 16:
        if (*p == 'X') c = 'F';
        else c = 'f';
        break;
      case 8:
        c = '7'; break;
      case 2:
        c = '1'; break;
    }
    return c;
}

#define FNONE  0
#define FSHARP 1
#define FMINUS 2
#define FPLUS  4
#define FZERO  8
#define FSPACE 16
#define FWIDTH 32
#define FPREC  64

#define CHECK(l) do {\
    while (blen + (l) >= bsiz) {\
        bsiz*=2;\
    }\
    rb_str_resize(result, bsiz);\
    buf = RSTRING(result)->ptr;\
} while (0)

#define PUSH(s, l) do { \
    CHECK(l);\
    memcpy(&buf[blen], s, l);\
    blen += (l);\
} while (0)

#define GETARG() (nextvalue != Qundef ? nextvalue : \
    posarg < 0 ? \
    (rb_raise(rb_eArgError, "unnumbered(%d) mixed with numbered", nextarg), 0) : \
    (posarg = nextarg++, GETNTHARG(posarg)))

#define GETPOSARG(n) (posarg > 0 ? \
    (rb_raise(rb_eArgError, "numbered(%d) after unnumbered(%d)", n, posarg), 0) : \
    ((n < 1) ? (rb_raise(rb_eArgError, "invalid index - %d$", n), 0) : \
               (posarg = -1, GETNTHARG(n))))

#define GETNTHARG(nth) \
    ((nth >= argc) ? (rb_raise(rb_eArgError, "too few arguments."), 0) : argv[nth])

#define GETASTER(val) do { \
    t = p++; \
    n = 0; \
    for (; p < end && ISDIGIT(*p); p++) { \
        n = 10 * n + (*p - '0'); \
    } \
    if (p >= end) { \
        rb_raise(rb_eArgError, "malformed format string - %%*[0-9]"); \
    } \
    if (*p == '$') { \
        tmp = GETPOSARG(n); \
    } \
    else { \
        tmp = GETARG(); \
        p = t; \
    } \
    val = NUM2INT(tmp); \
} while (0)


/*
 *  call-seq:
 *     format(format_string [, arguments...] )   => string
 *     sprintf(format_string [, arguments...] )  => string
 *  
 *  Returns the string resulting from applying <i>format_string</i> to
 *  any additional arguments. Within the format string, any characters
 *  other than format sequences are copied to the result. A format
 *  sequence consists of a percent sign, followed by optional flags,
 *  width, and precision indicators, then terminated with a field type
 *  character. The field type controls how the corresponding
 *  <code>sprintf</code> argument is to be interpreted, while the flags
 *  modify that interpretation. The field type characters are listed
 *  in the table at the end of this section. The flag characters are:
 *
 *    Flag     | Applies to   | Meaning
 *    ---------+--------------+-----------------------------------------
 *    space    | bdeEfgGioxXu | Leave a space at the start of 
 *             |              | positive numbers.
 *    ---------+--------------+-----------------------------------------
 *    (digit)$ | all          | Specifies the absolute argument number
 *             |              | for this field. Absolute and relative
 *             |              | argument numbers cannot be mixed in a
 *             |              | sprintf string.
 *    ---------+--------------+-----------------------------------------
 *     #       | beEfgGoxX    | Use an alternative format. For the
 *             |              | conversions `o', `x', `X', and `b', 
 *             |              | prefix the result with ``0'', ``0x'', ``0X'',
 *             |              |  and ``0b'', respectively. For `e',
 *             |              | `E', `f', `g', and 'G', force a decimal
 *             |              | point to be added, even if no digits follow.
 *             |              | For `g' and 'G', do not remove trailing zeros.
 *    ---------+--------------+-----------------------------------------
 *    +        | bdeEfgGioxXu | Add a leading plus sign to positive numbers.
 *    ---------+--------------+-----------------------------------------
 *    -        | all          | Left-justify the result of this conversion.
 *    ---------+--------------+-----------------------------------------
 *    0 (zero) | all          | Pad with zeros, not spaces.
 *    ---------+--------------+-----------------------------------------
 *    *        | all          | Use the next argument as the field width. 
 *             |              | If negative, left-justify the result. If the
 *             |              | asterisk is followed by a number and a dollar 
 *             |              | sign, use the indicated argument as the width.
 *
 *     
 *  The field width is an optional integer, followed optionally by a
 *  period and a precision. The width specifies the minimum number of
 *  characters that will be written to the result for this field. For
 *  numeric fields, the precision controls the number of decimal places
 *  displayed. For string fields, the precision determines the maximum
 *  number of characters to be copied from the string. (Thus, the format
 *  sequence <code>%10.10s</code> will always contribute exactly ten
 *  characters to the result.)
 *
 *  The field types are:
 *
 *      Field |  Conversion
 *      ------+--------------------------------------------------------------
 *        b   | Convert argument as a binary number.
 *        c   | Argument is the numeric code for a single character.
 *        d   | Convert argument as a decimal number.
 *        E   | Equivalent to `e', but uses an uppercase E to indicate
 *            | the exponent.
 *        e   | Convert floating point argument into exponential notation 
 *            | with one digit before the decimal point. The precision
 *            | determines the number of fractional digits (defaulting to six).
 *        f   | Convert floating point argument as [-]ddd.ddd, 
 *            |  where the precision determines the number of digits after
 *            | the decimal point.
 *        G   | Equivalent to `g', but use an uppercase `E' in exponent form.
 *        g   | Convert a floating point number using exponential form
 *            | if the exponent is less than -4 or greater than or
 *            | equal to the precision, or in d.dddd form otherwise.
 *        i   | Identical to `d'.
 *        o   | Convert argument as an octal number.
 *        p   | The valuing of argument.inspect.
 *        s   | Argument is a string to be substituted. If the format
 *            | sequence contains a precision, at most that many characters
 *            | will be copied.
 *        u   | Treat argument as an unsigned decimal number.
 *        X   | Convert argument as a hexadecimal number using uppercase
 *            | letters. Negative numbers will be displayed with two
 *            | leading periods (representing an infinite string of
 *            | leading 'FF's.
 *        x   | Convert argument as a hexadecimal number.
 *            | Negative numbers will be displayed with two
 *            | leading periods (representing an infinite string of
 *            | leading 'ff's.
 *     
 *  Examples:
 *
 *     sprintf("%d %04x", 123, 123)               #=> "123 007b"
 *     sprintf("%08b '%4s'", 123, 123)            #=> "01111011 ' 123'"
 *     sprintf("%1$*2$s %2$d %1$s", "hello", 8)   #=> "   hello 8 hello"
 *     sprintf("%1$*2$s %2$d", "hello", -8)       #=> "hello    -8"
 *     sprintf("%+g:% g:%-g", 1.23, 1.23, 1.23)   #=> "+1.23: 1.23:1.23"
 */

VALUE
rb_f_sprintf(argc, argv)
    int argc;
    VALUE *argv;
{
    VALUE fmt;
    const char *p, *end;
    char *buf;
    int blen, bsiz;
    VALUE result;

    int width, prec, flags = FNONE;
    int nextarg = 1;
    int posarg = 0;
    int tainted = 0;
    VALUE nextvalue;
    VALUE tmp;
    VALUE str;

    fmt = GETNTHARG(0);
    if (OBJ_TAINTED(fmt)) tainted = 1;
    StringValue(fmt);
    fmt = rb_str_new4(fmt);
    p = RSTRING(fmt)->ptr;
    end = p + RSTRING(fmt)->len;
    blen = 0;
    bsiz = 120;
    result = rb_str_buf_new(bsiz);
    buf = RSTRING(result)->ptr;

    for (; p < end; p++) {
        const char *t;
        int n;

        for (t = p; t < end && *t != '%'; t++) ;
        PUSH(p, t - p);
        if (t >= end) {
            /* end of fmt string */
            goto sprint_exit;
        }
        p = t + 1;              /* skip `%' */

        width = prec = -1;
        nextvalue = Qundef;
      retry:
        switch (*p) {
          default:
            if (ISPRINT(*p))
                rb_raise(rb_eArgError, "malformed format string - %%%c", *p);
            else
                rb_raise(rb_eArgError, "malformed format string");
            break;

          case ' ':
            flags |= FSPACE;
            p++;
            goto retry;

          case '#':
            flags |= FSHARP;
            p++;
            goto retry;

          case '+':
            flags |= FPLUS;
            p++;
            goto retry;

          case '-':
            flags |= FMINUS;
            p++;
            goto retry;

          case '0':
            flags |= FZERO;
            p++;
            goto retry;

          case '1': case '2': case '3': case '4':
          case '5': case '6': case '7': case '8': case '9':
            n = 0;
            for (; p < end && ISDIGIT(*p); p++) {
                n = 10 * n + (*p - '0');
            }
            if (p >= end) {
                rb_raise(rb_eArgError, "malformed format string - %%[0-9]");
            }
            if (*p == '$') {
                if (nextvalue != Qundef) {
                    rb_raise(rb_eArgError, "value given twice - %d$", n);
                }
                nextvalue = GETPOSARG(n);
                p++;
                goto retry;
            }
            width = n;
            flags |= FWIDTH;
            goto retry;

          case '*':
            if (flags & FWIDTH) {
                rb_raise(rb_eArgError, "width given twice");
            }

            flags |= FWIDTH;
            GETASTER(width);
            if (width < 0) {
                flags |= FMINUS;
                width = -width;
            }
            p++;
            goto retry;

          case '.':
            if (flags & FPREC) {
                rb_raise(rb_eArgError, "precision given twice");
            }
            flags |= FPREC;

            prec = 0;
            p++;
            if (*p == '*') {
                GETASTER(prec);
                if (prec < 0) { /* ignore negative precision */
                    flags &= ~FPREC;
                }
                p++;
                goto retry;
            }

            for (; p < end && ISDIGIT(*p); p++) {
                prec = 10 * prec + (*p - '0');
            }
            if (p >= end) {
                rb_raise(rb_eArgError, "malformed format string - %%.[0-9]");
            }
            goto retry;

          case '\n':
            p--;
          case '\0':
          case '%':
            if (flags != FNONE) {
                rb_raise(rb_eArgError, "illegal format character - %%");
            }
            PUSH("%", 1);
            break;

          case 'c':
            {
                VALUE val = GETARG();
                char c;

                if (!(flags & FMINUS))
                    while (--width > 0)
                        PUSH(" ", 1);
                c = NUM2INT(val) & 0xff;
                PUSH(&c, 1);
                while (--width > 0)
                    PUSH(" ", 1);
            }
            break;

          case 's':
          case 'p':
            {
                VALUE arg = GETARG();
                long len;

                if (*p == 'p') arg = rb_inspect(arg);
                str = rb_obj_as_string(arg);
                if (OBJ_TAINTED(str)) tainted = 1;
                len = RSTRING(str)->len;
                if (flags&FPREC) {
                    if (prec < len) {
                        len = prec;
                    }
                }
                if (flags&FWIDTH) {
                    if (width > len) {
                        CHECK(width);
                        width -= len;
                        if (!(flags&FMINUS)) {
                            while (width--) {
                                buf[blen++] = ' ';
                            }
                        }
                        memcpy(&buf[blen], RSTRING(str)->ptr, len);
                        blen += len;
                        if (flags&FMINUS) {
                            while (width--) {
                                buf[blen++] = ' ';
                            }
                        }
                        break;
                    }
                }
                PUSH(RSTRING(str)->ptr, len);
            }
            break;

          case 'd':
          case 'i':
          case 'o':
          case 'x':
          case 'X':
          case 'b':
          case 'B':
          case 'u':
            {
                volatile VALUE val = GETARG();
                char fbuf[32], nbuf[64], *s, *t;
                char *prefix = 0;
                int sign = 0;
                char sc = 0;
                long v = 0;
                int base, bignum = 0;
                int len, pos;
                VALUE tmp;

                switch (*p) {
                  case 'd':
                  case 'i':
                    sign = 1; break;
                  case 'o':
                  case 'x':
                  case 'X':
                  case 'b':
                  case 'B':
                  case 'u':
                  default:
                    if (flags&(FPLUS|FSPACE)) sign = 1;
                    break;
                }
                if (flags & FSHARP) {
                    switch (*p) {
                      case 'o':
                        prefix = "0"; break;
                      case 'x':
                        prefix = "0x"; break;
                      case 'X':
                        prefix = "0X"; break;
                      case 'b':
                        prefix = "0b"; break;
                      case 'B':
                        prefix = "0B"; break;
                    }
                    if (prefix) {
                        width -= strlen(prefix);
                    }
                }

              bin_retry:
                switch (TYPE(val)) {
                  case T_FLOAT:
                    val = rb_dbl2big(RFLOAT(val)->value);
                    if (FIXNUM_P(val)) goto bin_retry;
                    bignum = 1;
                    break;
                  case T_STRING:
                    val = rb_str_to_inum(val, 0, Qtrue);
                    goto bin_retry;
                  case T_BIGNUM:
                    bignum = 1;
                    break;
                  case T_FIXNUM:
                    v = FIX2LONG(val);
                    break;
                  default:
                    val = rb_Integer(val);
                    goto bin_retry;
                }

                switch (*p) {
                  case 'o':
                    base = 8; break;
                  case 'x':
                  case 'X':
                    base = 16; break;
                  case 'b':
                  case 'B':
                    base = 2; break;
                  case 'u':
                  case 'd':
                  case 'i':
                  default:
                    base = 10; break;
                }
                if (!bignum) {
                    if (base == 2) {
                        val = rb_int2big(v);
                        goto bin_retry;
                    }
                    if (sign) {
                        char c = *p;
                        if (c == 'i') c = 'd'; /* %d and %i are identical */
                        if (v < 0) {
                            v = -v;
                            sc = '-';
                            width--;
                        }
                        else if (flags & FPLUS) {
                            sc = '+';
                            width--;
                        }
                        else if (flags & FSPACE) {
                            sc = ' ';
                            width--;
                        }
                        sprintf(fbuf, "%%l%c", c);
                        sprintf(nbuf, fbuf, v);
                        s = nbuf;
                        goto format_integer;
                    }
                    s = nbuf;
                    if (v < 0) {
                        if (base == 10) {
                            rb_warning("negative number for %%u specifier");
                        }
                        if (!(flags&(FPREC|FZERO))) {
                            strcpy(s, "..");
                            s += 2;
                        }
                    }
                    sprintf(fbuf, "%%l%c", *p == 'X' ? 'x' : *p);
                    sprintf(s, fbuf, v);
                    if (v < 0) {
                        char d = 0;

                        remove_sign_bits(s, base);
                        switch (base) {
                          case 16:
                            d = 'f'; break;
                          case 8:
                            d = '7'; break;
                        }
                        if (d && *s != d) {
                            memmove(s+1, s, strlen(s)+1);
                            *s = d;
                        }
                    }
                    s = nbuf;
                    goto format_integer;
                }

                if (sign) {
                    tmp = rb_big2str(val, base);
                    s = RSTRING(tmp)->ptr;
                    if (s[0] == '-') {
                        s++;
                        sc = '-';
                        width--;
                    }
                    else if (flags & FPLUS) {
                        sc = '+';
                        width--;
                    }
                    else if (flags & FSPACE) {
                        sc = ' ';
                        width--;
                    }
                    goto format_integer;
                }
                if (!RBIGNUM(val)->sign) {
                    val = rb_big_clone(val);
                    rb_big_2comp(val);
                }
                tmp = rb_big2str(val, base);
                s = RSTRING(tmp)->ptr;
                if (*s == '-') {
                    if (base == 10) {
                        rb_warning("negative number for %%u specifier");
                        s++;
                    }
                    else {
                        remove_sign_bits(++s, base);
                        tmp = rb_str_new(0, 3+strlen(s));
                        t = RSTRING(tmp)->ptr;
                        if (!(flags&(FPREC|FZERO))) {
                            strcpy(t, "..");
                            t += 2;
                        }
                        switch (base) {
                          case 16:
                            if (s[0] != 'f') strcpy(t++, "f"); break;
                          case 8:
                            if (s[0] != '7') strcpy(t++, "7"); break;
                          case 2:
                            if (s[0] != '1') strcpy(t++, "1"); break;
                        }
                        strcpy(t, s);
                        bignum = 2;
                    }
                }
                s = RSTRING(tmp)->ptr;

              format_integer:
                pos = -1;
                len = strlen(s);

                if (*p == 'X') {
                    char *pp = s;
                    while (*pp) {
                        *pp = toupper(*pp);
                        pp++;
                    }
                }
                if ((flags&(FZERO|FPREC)) == FZERO) {
                    prec = width;
                    width = 0;
                }
                else {
                    if (prec < len) prec = len;
                    width -= prec;
                }
                if (!(flags&FMINUS)) {
                    CHECK(width);
                    while (width-- > 0) {
                        buf[blen++] = ' ';
                    }
                }
                if (sc) PUSH(&sc, 1);
                if (prefix) {
                    int plen = strlen(prefix);
                    PUSH(prefix, plen);
                }
                CHECK(prec - len);
                if (!bignum && v < 0) {
                    char c = sign_bits(base, p);
                    while (len < prec--) {
                        buf[blen++] = c;
                    }
                }
                else {
                    char c;

                    if (bignum && !RBIGNUM(val)->sign)
                        c = sign_bits(base, p);
                    else
                        c = '0';
                    while (len < prec--) {
                        buf[blen++] = c;
                    }
                }
                PUSH(s, len);
                CHECK(width);
                while (width-- > 0) {
                    buf[blen++] = ' ';
                }
            }
            break;

          case 'f':
          case 'g':
          case 'G':
          case 'e':
          case 'E':
            {
                VALUE val = GETARG();
                double fval;
                int i, need = 6;
                char fbuf[32];

                fval = RFLOAT(rb_Float(val))->value;
#if defined(_WIN32) && !defined(__BORLANDC__)
                if (isnan(fval) || isinf(fval)) {
                    char *expr;

                    if  (isnan(fval)) {
                        expr = "NaN";
                    }
                    else {
                        expr = "Inf";
                    }
                    need = strlen(expr);
                    if ((!isnan(fval) && fval < 0.0) || (flags & FPLUS))
                        need++;
                    if ((flags & FWIDTH) && need < width)
                        need = width;

                    CHECK(need);
                    sprintf(&buf[blen], "%*s", need, "");
                    if (flags & FMINUS) {
                        if (!isnan(fval) && fval < 0.0)
                            buf[blen++] = '-';
                        else if (flags & FPLUS)
                            buf[blen++] = '+';
                        else if (flags & FSPACE)
                            blen++;
                        strncpy(&buf[blen], expr, strlen(expr));
                    }
                    else if (flags & FZERO) {
                        if (!isnan(fval) && fval < 0.0) {
                            buf[blen++] = '-';
                            need--;
                        }
                        else if (flags & FPLUS) {
                            buf[blen++] = '+';
                            need--;
                        }
                        else if (flags & FSPACE) {
                            blen++;
                            need--;
                        }
                        while (need-- - strlen(expr) > 0) {
                            buf[blen++] = '0';
                        }
                        strncpy(&buf[blen], expr, strlen(expr));
                    }
                    else {
                        if (!isnan(fval) && fval < 0.0)
                            buf[blen + need - strlen(expr) - 1] = '-';
                        else if (flags & FPLUS)
                            buf[blen + need - strlen(expr) - 1] = '+';
                        strncpy(&buf[blen + need - strlen(expr)], expr,
                                strlen(expr));
                    }
                    blen += strlen(&buf[blen]);
                    break;
                }
#endif  /* defined(_WIN32) && !defined(__BORLANDC__) */
                fmt_setup(fbuf, *p, flags, width, prec);
                need = 0;
                if (*p != 'e' && *p != 'E') {
                    i = INT_MIN;
                    frexp(fval, &i);
                    if (i > 0)
                        need = BIT_DIGITS(i);
                }
                need += (flags&FPREC) ? prec : 6;
                if ((flags&FWIDTH) && need < width)
                    need = width;
                need += 20;

                CHECK(need);
                sprintf(&buf[blen], fbuf, fval);
                blen += strlen(&buf[blen]);
            }
            break;
        }
        flags = FNONE;
    }

  sprint_exit:
    /* XXX - We cannot validiate the number of arguments because
     *       the format string may contain `n$'-style argument selector.
     */
    if (RTEST(ruby_verbose) && posarg >= 0 && nextarg < argc) {
        rb_raise(rb_eArgError, "too many arguments for format string");
    }
    rb_str_resize(result, blen);

    if (tainted) OBJ_TAINT(result);
    return result;
}

static void
fmt_setup(buf, c, flags, width, prec)
    char *buf;
    int c;
    int flags, width, prec;
{
    *buf++ = '%';
    if (flags & FSHARP) *buf++ = '#';
    if (flags & FPLUS)  *buf++ = '+';
    if (flags & FMINUS) *buf++ = '-';
    if (flags & FZERO)  *buf++ = '0';
    if (flags & FSPACE) *buf++ = ' ';

    if (flags & FWIDTH) {
        sprintf(buf, "%d", width);
        buf += strlen(buf);
    }

    if (flags & FPREC) {
        sprintf(buf, ".%d", prec);
        buf += strlen(buf);
    }

    *buf++ = c;
    *buf = '\0';
}

---