Implement %iftoken, test for a single token

Implement %iftoken, a test for a single token.  This is useful in
cases using %+ to splice a macro-provided token.

doc/nasmdoc.src

@@ -2659,7 +2659,6 @@ Like most other \c{%if} constructs, \c{%ifidn} has a counterpart
 Similarly, \c{%ifidni} has counterparts \i\c{%elifidni},
 \i\c{%ifnidni} and \i\c{%elifnidni}.
 
-
 \S{iftyp} \i\c{%ifid}, \i\c{%ifnum}, \i\c{%ifstr}: Testing Token
 Types\I{testing, token types}
 
@@ -2721,6 +2720,21 @@ which case, all but the first two would be lumped together into
 The usual \c{%elifXXX}, \c{%ifnXXX} and \c{%elifnXXX} versions exist
 for each of \c{%ifid}, \c{%ifnum} and \c{%ifstr}.
 
+\S{iftoken} \i\c{%iftoken}: Test For A Single Token
+
+Some macros will want to do different things depending on if it is
+passed a single token (e.g. paste it to something else using \c{%+})
+versus a multi-token sequence.
+
+The conditional assembly construct \c{%iftoken} assembles the
+subsequent code if and only if the expanded parameters consist of
+exactly one token, possibly surrounded by whitespace.
+
+For example, \c{1} will assemble the subsequent code, but \c{-1} will
+not (\c{-} being an operator.)
+
+The usual \i\c{%eliftoken}, \i\c\{%ifntoken}, and \i\c{%elifntoken}
+variants are also provided.
 
 \S{pperror} \i\c{%error}: Reporting \i{User-Defined Errors}
 

pptok.dat

@@ -10,6 +10,7 @@
 *idni
 *macro
 *num
+*token
 *str
 %arg
 %assign

preproc.c

@@ -1594,7 +1594,21 @@ static bool if_condition(Token * tline, enum preproc_token ct)
 		!t->text[1]))
 	    t = t->next;
 	
-	j = t && t->type == needtype;
+	j = tok_type_(t, needtype);
+	break;
+
+    case PPC_IFTOKEN:
+	t = tline = expand_smacro(tline);
+	while (tok_type_(t, TOK_WHITESPACE))
+	    t = t->next;
+
+	j = false;
+	if (t) {
+	    t = t->next;	/* Skip the actual token */
+	    while (tok_type_(t, TOK_WHITESPACE))
+		t = t->next;
+	    j = !t;		/* Should be nothing left */
+	}
 	break;
 
     case PPC_IF:

test/iftoken.asm

@@ -0,0 +1,108 @@
+	db 'N "1": '
+%iftoken 1
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif
+	db 'C "1": '
+%iftoken 1 ; With a comment!
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif
+	db 'N "+1": '
+%iftoken +1
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif
+	db 'C "+1": '
+%iftoken +1 ; With a comment!
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif
+	db 'N "1 2": '
+%iftoken 1 2
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif
+	db 'C "1 2": '
+%iftoken 1 2 ; With a comment!
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif
+	db 'N "1,2": '
+%iftoken 1,2
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif
+	db 'C "1,2": '
+%iftoken 1,2 ; With a comment!
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif
+	db 'N "foo": '
+%iftoken foo
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif
+	db 'C "foo": '
+%iftoken foo ; With a comment!
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif
+	db 'N "foo bar": '
+%iftoken foo bar
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif
+	db 'C "foo bar": '
+%iftoken foo bar ; With a comment!
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif
+	db 'N "%": '
+%iftoken %
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif
+	db 'C "%": '
+%iftoken % ; With a comment!
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif
+	db 'N "+foo": '
+%iftoken +foo
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif
+	db 'C "+foo": '
+%iftoken +foo ; With a comment!
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif
+	db 'N "<<": '
+%iftoken <<
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif
+	db 'C "<<": '
+%iftoken << ; With a comment!
+	db 'Yes', 10
+%else
+	db 'No', 10
+%endif

test/iftoken.pl

@@ -0,0 +1,19 @@
+#!/usr/bin/perl
+
+@list = ('1', '+1', '1 2', '1,2', 'foo', 'foo bar', '%', '+foo', '<<');
+
+foreach $t (@list) {
+    print "\tdb 'N \"$t\": '\n";
+    print "%iftoken $t\n";
+    print "\tdb 'Yes', 10\n";
+    print "%else\n";
+    print "\tdb 'No', 10\n";
+    print "%endif\n";
+
+    print "\tdb 'C \"$t\": '\n";
+    print "%iftoken $t ; With a comment!\n";
+    print "\tdb 'Yes', 10\n";
+    print "%else\n";
+    print "\tdb 'No', 10\n";
+    print "%endif\n";
+}