From 523e445c3456641012bd0cd142875c941eb52fc3 Mon Sep 17 00:00:00 2001
From: Ali Gholami Rudi <ali@rudi.ir>
Date: Sat, 4 Feb 2012 23:27:39 +0330
Subject: [PATCH] troff: comment space handling variables

---
 troff.c | 44 ++++++++++++++++++++++++++++++++++----------
 1 file changed, 34 insertions(+), 10 deletions(-)

diff --git a/troff.c b/troff.c
index fa1b8e5..0793afe 100644
--- a/troff.c
+++ b/troff.c
@@ -1,12 +1,35 @@
+/*
+ * The main challenge in troff backend is managing unnecessary spaces:
+ * + no newline should appear in the output, except in blocks
+ * + no excess whitespace should appear after inline dot commands
+ *   like footnotes
+ *
+ * troff_put() manages white spaces:
+ * + gotnl: is set when the last character is a newline
+ * + eatspc: when one, ignore as much space as possible
+ * + inblk: we are in a block and no whitespace processing should be done
+ *
+ * After printing an inline macro, eatspc_on() is called which forces
+ * troff_put() to ignore all whitespaces until the first
+ * non-space character.  Some care is necessary when handling dots; if
+ * a dot appears just after a newline, it is a troff macro, otherwise
+ * it is a printable dot and should be escaped.
+ */
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 #include "ctxt.h"
 
-static int eatspc;	/* jump space chars; always after a newline */
-static int gotnl;	/* last output char was a space */
+static int eatspc;	/* jump space chars */
+static int gotnl;	/* last output char was a newline */
 static int inblk;	/* inside a block */
 
+static void eatspc_on(void)
+{
+	gotnl = 0;
+	eatspc = 1;
+}
+
 static void troff_doc_beg(struct doc *doc)
 {
 }
@@ -24,12 +47,13 @@ static void troff_put(struct doc *doc, char *s)
 		return;
 	}
 	if (eatspc) {
-		while (*s == ' ' || *s == '\t' || (*s == '\n' && s[1] != '.'))
-			s++;
+		while (*s == ' ' || *s == '\t' || *s == '\n')
+			gotnl = *s++ == '\n';
 		eatspc = *s == '\0';	/* more eatspc if s was space */
-		gotnl = *s != '.';	/* set gotnl, unless there is a dot */
-		if (*s == '.')
+		if (!gotnl && *s == '.')
 			doc_write(doc, "\\&");
+		else if (!eatspc)	/* exiting eatspc; set gotnl */
+			gotnl = 1;
 	}
 	while (gotnl && *s == '\n')
 		s++;
@@ -78,7 +102,7 @@ static void troff_list_beg(struct doc *doc)
 	troff_put(doc, "\n.br\n");
 	if (!ldepth)
 		troff_put(doc, ".sp 1\n");
-	eatspc = 1;
+	eatspc_on();
 	ldepth++;
 	if (ldepth > 1)
 		doc_write(doc, ".RS\n");
@@ -94,7 +118,7 @@ static void troff_list_end(struct doc *doc)
 static void troff_item_beg(struct doc *doc)
 {
 	doc_write(doc, ".IP \\(bu 2\n");
-	eatspc = 1;
+	eatspc_on();
 }
 
 static void troff_item_end(struct doc *doc)
@@ -136,13 +160,13 @@ static void troff_put_txt(struct doc *doc, char *s, char *m)
 		troff_put(doc, "\n.[[\n");
 		troff_put(doc, s);
 		troff_put(doc, "\n.]]\n");
-		eatspc = 1;
+		eatspc_on();
 		break;
 	case '[':
 		troff_put(doc, "\n.FS\n");
 		troff_put(doc, s);
 		troff_put(doc, "\n.FE\n");
-		eatspc = 1;
+		eatspc_on();
 		break;
 	default:
 		sprintf(b, "%c%s%c", m[0], s, m[1]);
-- 
2.11.4.GIT