From 7d50fd267d9d838ea1413e6b2cced8ba0d069864 Mon Sep 17 00:00:00 2001
From: vsc <vsc@b08c6af1-5177-4d33-ba66-4b1c6b8b522a>
Date: Tue, 19 Jun 2001 16:31:59 +0000
Subject: [PATCH] parser should parse +inf,-inf,+nan,-nan as floating point
 numbers write should write inf as +inf and nan as +nan

git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@92 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
---
 C/parser.c | 31 +++++++++++++++++++++++++++++++
 C/write.c  |  2 ++
 2 files changed, 33 insertions(+)

diff --git a/C/parser.c b/C/parser.c
index a5d956464..198b8640a 100644
--- a/C/parser.c
+++ b/C/parser.c
@@ -343,6 +343,14 @@ ParseList(void)
   return (t);
 }
 
+#ifndef INFINITY
+#define INFINITY (1.0/0.0)
+#endif
+
+#ifndef NAN
+#define NAN      (0.0/0.0)
+#endif
+
 static Term
 ParseTerm(int prio)
 {
@@ -387,6 +395,29 @@ ParseTerm(int prio)
 	  NextToken;
 	  break;
 	}
+      } else if (tokptr->Tok == Name_tok) {
+	Atom at = (Atom)tokptr->TokInfo;
+	if ((Atom)t == AtomPlus) {
+	  if (at == AtomInf) {
+	    t = MkFloatTerm(INFINITY);
+	    NextToken;
+	    break;
+	  } else if (at == AtomNan) {
+	    t = MkFloatTerm(NAN);
+	    NextToken;
+	    break;
+	  }
+	} else if ((Atom)t == AtomMinus) {
+	  if (at == AtomInf) {
+	    t = MkFloatTerm(-INFINITY);
+	    NextToken;
+	    break;
+	  } else if (at == AtomNan) {
+	    t = MkFloatTerm(NAN);
+	    NextToken;
+	    break;
+	  }
+	}
       }
       if (opprio <= prio) {
       /* try to parse as a prefix operator */
diff --git a/C/write.c b/C/write.c
index b84320d99..671ffe8db 100644
--- a/C/write.c
+++ b/C/write.c
@@ -126,6 +126,8 @@ wrputf(Float f)			/* writes a float	 */
   sprintf(s, "%.6g", f);
   while (*pt == ' ')
     pt++;
+  if (*pt == 'i' || *pt == 'n')  /* inf or nan */
+    wrputc('+');    
   wrputs(pt);
   if (*pt == '-') pt++;
   while ((ch = *pt) != '\0') {