1 files changed, 156 insertions, 0 deletions
diff --git a/src/cmd/htmlroff/t16.c b/src/cmd/htmlroff/t16.c
new file mode 100644
index 00000000..3a9c427e
--- /dev/null
+++ b/src/cmd/htmlroff/t16.c
@@ -0,0 +1,156 @@
+#include "a.h"
+
+/*
+ * 16. Conditional acceptance of input.
+ *
+ *	conditions are
+ *		c - condition letter (o, e, t, n)
+ *		!c - not c
+ *		N - N>0
+ *		!N - N <= 0
+ *		'a'b' - if a==b
+ *		!'a'b'	- if a!=b
+ *
+ *	\{xxx\} can be used for newline in bodies
+ *
+ *	.if .ie .el
+ *
+ */
+
+int iftrue[20];
+int niftrue;
+
+void
+startbody(void)
+{
+	int c;
+			
+	while((c = getrune()) == ' ' || c == '\t')
+		;
+	ungetrune(c);
+}
+
+void
+skipbody(void)
+{
+	int c, cc, nbrace;
+
+	nbrace = 0;
+	for(cc=0; (c = getrune()) >= 0; cc=c){
+		if(c == '\n' && nbrace <= 0)
+			break;
+		if(cc == '\\' && c == '{')
+			nbrace++;
+		if(cc == '\\' && c == '}')
+			nbrace--;
+	}
+}
+
+int
+ifeval(void)
+{
+	int c, cc, neg, nc;
+	Rune line[MaxLine], *p, *e, *q;
+	Rune *a;
+	
+	while((c = getnext()) == ' ' || c == '\t')
+		;
+	neg = 0;
+	while(c == '!'){
+		neg = !neg;
+		c = getnext();
+	}
+
+	if('0' <= c && c <= '9'){
+		ungetnext(c);
+		a = copyarg();
+		c = (eval(a)>0) ^ neg;
+		free(a);
+		return c;
+	}
+	
+	switch(c){
+	case ' ':
+	case '\n':
+		ungetnext(c);
+		return !neg;
+	case 'o':	/* odd page */
+	case 't':	/* troff */
+	case 'h':	/* htmlroff */
+		while((c = getrune()) != ' ' && c != '\t' && c != '\n' && c >= 0)
+			;
+		return 1 ^ neg;
+	case 'n':	/* nroff */
+	case 'e':	/* even page */
+		while((c = getnext()) != ' ' && c != '\t' && c != '\n' && c >= 0)
+			;
+		return 0 ^ neg;
+	}
+
+	/* string comparison 'string1'string2' */
+	p = line;
+	e = p+nelem(line);
+	nc = 0;
+	q = nil;
+	while((cc=getnext()) >= 0 && cc != '\n' && p<e){
+		if(cc == c){
+			if(++nc == 2)
+				break;
+			q = p;
+		}
+		*p++ = cc;
+	}
+	if(cc != c){
+		ungetnext(cc);
+		return 0;
+	}
+	if(nc < 2){
+		return 0;
+	}
+	*p = 0;
+	return (q-line == p-(q+1)
+		&& memcmp(line, q+1, (q-line)*sizeof(Rune))==0) ^ neg;
+}
+	
+void
+r_if(Rune *name)
+{
+	int n;
+	
+	n = ifeval();
+	if(runestrcmp(name, L("ie")) == 0){
+		if(niftrue >= nelem(iftrue))
+			sysfatal("%Cie overflow", dot);
+		iftrue[niftrue++] = n;
+	}
+	if(n)
+		startbody();
+	else
+		skipbody();
+}
+
+void
+r_el(Rune *name)
+{
+	USED(name);
+	
+	if(niftrue <= 0){
+		warn("%Cel underflow", dot);
+		return;
+	}
+	if(iftrue[--niftrue])
+		skipbody();
+	else
+		startbody();
+}
+
+void
+t16init(void)
+{
+	addraw(L("if"), r_if);
+	addraw(L("ie"), r_if);
+	addraw(L("el"), r_el);
+	
+	addesc('{', e_nop, HtmlMode|ArgMode);
+	addesc('}', e_nop, HtmlMode|ArgMode);
+}