* stream.c (vformat): num_buf increased to 256 because we

are now printing floating point numbers into it, letting
the C library handle precision which can generate many digits.
We cap the precision at at 128. New format specifiers ~e
and ~f implemented, which loosely correspond to those of printf.
The ~s and ~a directives handle floats similarly to ~g in
printf, except that they ensure that a decimal point is printed
for the non-exponential notation.

2 files changed, 65 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index f378d7ba..f3c1822a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,16 @@
 2012-03-19  Kaz Kylheku  <kaz@kylheku.com>
 
+	* stream.c (vformat): num_buf increased to 256 because we
+	are now printing floating point numbers into it, letting
+	the C library handle precision which can generate many digits.
+	We cap the precision at at 128. New format specifiers ~e
+	and ~f implemented, which loosely correspond to those of printf.
+	The ~s and ~a directives handle floats similarly to ~g in
+	printf, except that they ensure that a decimal point is printed
+	for the non-exponential notation.
+
+2012-03-19  Kaz Kylheku  <kaz@kylheku.com>
+
 	* configure (uintptr): New variable. Indicates whether unsigned
 	version of intptr_t is available and should be generated in config.h
 	as uintptr_t.
diff --git a/stream.c b/stream.c
index 4a2e4e7f..2d7a6e94 100644
--- a/stream.c
+++ b/stream.c
@@ -967,7 +967,7 @@ val vformat(val stream, val fmtstr, va_list vl)
     for (;;) {
       val obj;
       wchar_t ch = *fmt++;
-      char num_buf[64], *pnum = num_buf;
+      char num_buf[256], *pnum = num_buf;
 
       switch (state) {
       case vf_init:
@@ -1113,6 +1113,40 @@ val vformat(val stream, val fmtstr, va_list vl)
             sprintf(num_buf, num_fmt->oct, value);
           }
           goto output_num;
+        case 'f': case 'e':
+          obj = va_arg(vl, val);
+
+          if (obj == nao)
+            goto premature;
+
+          {
+            double n;
+
+            if (bignump(obj))
+              uw_throwf(error_s, lit("format: ~s: bignum to float "
+                                     "conversion unsupported\n"), obj, nao);
+
+            if (fixnump(obj))
+              n = (double) c_num(obj);
+            else if (floatp(obj))
+              n = obj->fl.n;
+            else
+              uw_throwf(error_s, lit("format: ~~~a conversion requires "
+                                     "numeric arg: ~s given\n"),
+                        chr(ch), obj, nao);
+
+            /* guard against num_buf overflow */
+            if (precision > 128)
+              uw_throwf(error_s, lit("excessive precision in format: ~s\n"),
+                        num(precision), nao);
+
+            if (ch == 'e')
+              sprintf(num_buf, "%.*e", precision, obj->fl.n);
+            else
+              sprintf(num_buf, "%.*f", precision, obj->fl.n);
+            precision = 0;
+            goto output_num;
+          }
         case 'a': case 's':
           obj = va_arg(vl, val);
           if (obj == nao)
@@ -1127,6 +1161,25 @@ val vformat(val stream, val fmtstr, va_list vl)
               pnum = (char *) chk_malloc(nchars + 1);
             mp_toradix(mp(obj), (unsigned char *) pnum, 10);
             goto output_num;
+          } else if (floatp(obj)) {
+            sprintf(num_buf, "%g", obj->fl.n);
+
+            if (!precision) {
+              if (!strpbrk(num_buf, "e."))
+                strcat(num_buf, ".0");
+            } else {
+              /* guard against num_buf overflow */
+              if (precision > 128)
+                uw_throwf(error_s, lit("excessive precision in format: ~s\n"),
+                          num(precision), nao);
+
+              if (strchr(num_buf, 'e'))
+                sprintf(num_buf, "%.*e", precision, obj->fl.n);
+              else
+                sprintf(num_buf, "%.*f", precision, obj->fl.n);
+              precision = 0;
+            }
+            goto output_num;
           } else if (width != 0) {
             val str = format(nil, ch == 'a' ? lit("~a") : lit("~s"), obj, nao);
             if (!vformat_str(stream, str, width, left, precision))