nobu	2017-04-23 10:04:40 +0900 (Sun, 23 Apr 2017)

  New Revision: 58454

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=58454

  Log:
    Refactor "%f" % Inf/NaN
    
    * sprintf.c (rb_str_format): as for non-finite float, calculate
      the exact needed size with the space flag.

  Modified files:
    trunk/sprintf.c
Index: sprintf.c
===================================================================
--- sprintf.c	(revision 58453)
+++ sprintf.c	(revision 58454)
@@ -1128,6 +1128,8 @@ rb_str_format(int argc, const VALUE *arg https://github.com/ruby/ruby/blob/trunk/sprintf.c#L1128
 		fval = RFLOAT_VALUE(rb_Float(val));
 		if (isnan(fval) || isinf(fval)) {
 		    const char *expr;
+		    int elen;
+		    char sign = '\0';
 
 		    if (isnan(fval)) {
 			expr = "NaN";
@@ -1136,31 +1138,28 @@ rb_str_format(int argc, const VALUE *arg https://github.com/ruby/ruby/blob/trunk/sprintf.c#L1138
 			expr = "Inf";
 		    }
 		    need = (int)strlen(expr);
-		    if ((!isnan(fval) && fval < 0.0) || (flags & (FPLUS|FSPACE)))
-			need++;
+		    elen = need;
+		    i = 0;
+		    if (!isnan(fval) && fval < 0.0)
+			sign = '-';
+		    else if (flags & (FPLUS|FSPACE))
+			sign = (flags & FPLUS) ? '+' : ' ';
+		    if (sign)
+			++need;
 		    if ((flags & FWIDTH) && need < width)
 			need = width;
 
-		    CHECK(need + 1);
-		    snprintf(&buf[blen], need + 1, "%*s", need, "");
+		    FILL(' ', need);
 		    if (flags & FMINUS) {
-			if (!isnan(fval) && fval < 0.0)
-			    buf[blen++] = '-';
-			else if (flags & FPLUS)
-			    buf[blen++] = '+';
-			else if (flags & FSPACE)
-			    blen++;
-			memcpy(&buf[blen], expr, strlen(expr));
+			if (sign)
+			    buf[blen - need--] = sign;
+			memcpy(&buf[blen - need], expr, elen);
 		    }
 		    else {
-			if (!isnan(fval) && fval < 0.0)
-			    buf[blen + need - strlen(expr) - 1] = '-';
-			else if (flags & FPLUS)
-			    buf[blen + need - strlen(expr) - 1] = '+';
-			memcpy(&buf[blen + need - strlen(expr)], expr,
-			       strlen(expr));
+			if (sign)
+			    buf[blen - elen - 1] = sign;
+			memcpy(&buf[blen - elen], expr, elen);
 		    }
-		    blen += strlen(&buf[blen]);
 		    break;
 		}
 

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