While i already got my fingers dirty on mandoc_escape(),

profit of the occasion to pull out some spaghetti, that is,
three confusing variables and fourteen pointless assignments
among them; instead, always operate on the official pointers
**start, **end, and *sz, each of which conveys an obvious meaning.

No functional change intended, and the new tests confirm that
everything still (err...) "works", as far as that word can be
applied to the kind of roff(7) mock-up code i'm polishing here.

"just commit" kristaps@

1 files changed, 65 insertions, 68 deletions

diff --git a/mandoc.c b/mandoc.c
index 20a6abf1..3ecf56bb 100644
--- a/mandoc.c
+++ b/mandoc.c
@@ -1,4 +1,4 @@
-/*	$Id: mandoc.c,v 1.64 2012/05/31 22:34:06 schwarze Exp $ */
+/*	$Id: mandoc.c,v 1.65 2012/05/31 22:38:16 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2011, 2012 Ingo Schwarze <schwarze@openbsd.org>
@@ -42,20 +42,33 @@ static	char	*time2a(time_t);
 enum mandoc_esc
 mandoc_escape(const char **end, const char **start, int *sz)
 {
-	char		 c, term;
-	int		 i, rlim;
-	const char	*cp, *rstart;
+	const char	*local_start;
+	int		 local_sz;
+	char		 term;
 	enum mandoc_esc	 gly; 
 
-	cp = *end;
-	rstart = cp;
-	if (start)
-		*start = rstart;
-	i = rlim = 0;
+	/*
+	 * When the caller doesn't provide return storage,
+	 * use local storage.
+	 */
+
+	if (NULL == start)
+		start = &local_start;
+	if (NULL == sz)
+		sz = &local_sz;
+
+	/*
+	 * Beyond the backslash, at least one input character
+	 * is part of the escape sequence.  With one exception
+	 * (see below), that character won't be returned.
+	 */
+
 	gly = ESCAPE_ERROR;
+	*start = ++*end;
+	*sz = 0;
 	term = '\0';
 
-	switch ((c = cp[i++])) {
+	switch ((*start)[-1]) {
 	/*
 	 * First the glyphs.  There are several different forms of
 	 * these, but each eventually returns a substring of the glyph
@@ -63,7 +76,7 @@ mandoc_escape(const char **end, const char **start, int *sz)
 	 */
 	case ('('):
 		gly = ESCAPE_SPECIAL;
-		rlim = 2;
+		*sz = 2;
 		break;
 	case ('['):
 		gly = ESCAPE_SPECIAL;
@@ -73,14 +86,15 @@ mandoc_escape(const char **end, const char **start, int *sz)
 		 * Unicode codepoint.  Here, however, only check whether
 		 * it's not a zero-width escape.
 		 */
-		if ('u' == cp[i] && ']' != cp[i + 1])
+		if ('u' == (*start)[0] && ']' != (*start)[1])
 			gly = ESCAPE_UNICODE;
 		term = ']';
 		break;
 	case ('C'):
-		if ('\'' != cp[i])
+		if ('\'' != **start)
 			return(ESCAPE_ERROR);
 		gly = ESCAPE_SPECIAL;
+		*start = ++*end;
 		term = '\'';
 		break;
 
@@ -91,7 +105,6 @@ mandoc_escape(const char **end, const char **start, int *sz)
 	 * let us just skip the next character.
 	 */
 	case ('z'):
-		(*end)++;
 		return(ESCAPE_SKIPCHAR);
 
 	/*
@@ -118,21 +131,17 @@ mandoc_escape(const char **end, const char **start, int *sz)
 	case ('f'):
 		if (ESCAPE_ERROR == gly)
 			gly = ESCAPE_FONT;
-
-		rstart= &cp[i];
-		if (start) 
-			*start = rstart;
-
-		switch (cp[i++]) {
+		switch (**start) {
 		case ('('):
-			rlim = 2;
+			*start = ++*end;
+			*sz = 2;
 			break;
 		case ('['):
+			*start = ++*end;
 			term = ']';
 			break;
 		default:
-			rlim = 1;
-			i--;
+			*sz = 1;
 			break;
 		}
 		break;
@@ -154,9 +163,10 @@ mandoc_escape(const char **end, const char **start, int *sz)
 	case ('X'):
 		/* FALLTHROUGH */
 	case ('Z'):
-		if ('\'' != cp[i++])
+		if ('\'' != **start)
 			return(ESCAPE_ERROR);
 		gly = ESCAPE_IGNORE;
+		*start = ++*end;
 		term = '\'';
 		break;
 
@@ -182,10 +192,11 @@ mandoc_escape(const char **end, const char **start, int *sz)
 	case ('w'):
 		/* FALLTHROUGH */
 	case ('x'):
+		if ('\'' != **start)
+			return(ESCAPE_ERROR);
 		if (ESCAPE_ERROR == gly)
 			gly = ESCAPE_IGNORE;
-		if ('\'' != cp[i++])
-			return(ESCAPE_ERROR);
+		*start = ++*end;
 		term = '\'';
 		break;
 
@@ -194,17 +205,17 @@ mandoc_escape(const char **end, const char **start, int *sz)
 	 * XXX Do any other escapes need similar handling?
 	 */
 	case ('N'):
-		if ('\0' == cp[i])
+		if ('\0' == **start)
 			return(ESCAPE_ERROR);
-		*end = &cp[++i];
-		if (isdigit((unsigned char)cp[i-1]))
+		(*end)++;
+		if (isdigit((unsigned char)**start)) {
+			*sz = 1;
 			return(ESCAPE_IGNORE);
+		}
+		(*start)++;
 		while (isdigit((unsigned char)**end))
 			(*end)++;
-		if (start)
-			*start = &cp[i];
-		if (sz)
-			*sz = *end - &cp[i];
+		*sz = *end - *start;
 		if ('\0' != **end)
 			(*end)++;
 		return(ESCAPE_NUMBERED);
@@ -215,54 +226,43 @@ mandoc_escape(const char **end, const char **start, int *sz)
 	case ('s'):
 		gly = ESCAPE_IGNORE;
 
-		rstart = &cp[i];
-		if (start) 
-			*start = rstart;
-
 		/* See +/- counts as a sign. */
-		c = cp[i];
-		if ('+' == c || '-' == c || ASCII_HYPH == c)
-			++i;
+		if ('+' == **end || '-' == **end || ASCII_HYPH == **end)
+			(*end)++;
 
-		switch (cp[i++]) {
+		switch (**end) {
 		case ('('):
-			rlim = 2;
+			*start = ++*end;
+			*sz = 2;
 			break;
 		case ('['):
+			*start = ++*end;
 			term = ']';
 			break;
 		case ('\''):
+			*start = ++*end;
 			term = '\'';
 			break;
 		default:
-			rlim = 1;
-			i--;
+			*sz = 1;
 			break;
 		}
 
-		/* See +/- counts as a sign. */
-		c = cp[i];
-		if ('+' == c || '-' == c || ASCII_HYPH == c)
-			++i;
-
 		break;
 
 	/*
 	 * Anything else is assumed to be a glyph.
+	 * In this case, pass back the character after the backslash.
 	 */
 	default:
 		gly = ESCAPE_SPECIAL;
-		rlim = 1;
-		i--;
+		*start = --*end;
+		*sz = 1;
 		break;
 	}
 
 	assert(ESCAPE_ERROR != gly);
 
-	*end = rstart = &cp[i];
-	if (start)
-		*start = rstart;
-
 	/*
 	 * Read up to the terminating character,
 	 * paying attention to nested escapes.
@@ -284,15 +284,13 @@ mandoc_escape(const char **end, const char **start, int *sz)
 				break;
 			}
 		}
-		rlim = (*end)++ - rstart;
+		*sz = (*end)++ - *start;
 	} else {
-		assert(rlim > 0);
-		if ((size_t)rlim > strlen(rstart))
+		assert(*sz > 0);
+		if ((size_t)*sz > strlen(*start))
 			return(ESCAPE_ERROR);
-		*end += rlim;
+		*end += *sz;
 	}
-	if (sz)
-		*sz = rlim;
 
 	/* Run post-processors. */
 
@@ -302,12 +300,13 @@ mandoc_escape(const char **end, const char **start, int *sz)
 		 * Pretend that the constant-width font modes are the
 		 * same as the regular font modes.
 		 */
-		if (2 == rlim && 'C' == *rstart)
-			rstart++;
-		else if (1 != rlim)
+		if (2 == *sz && 'C' == **start) {
+			(*start)++;
+			(*sz)--;
+		} else if (1 != *sz)
 			break;
 
-		switch (*rstart) {
+		switch (**start) {
 		case ('3'):
 			/* FALLTHROUGH */
 		case ('B'):
@@ -329,9 +328,7 @@ mandoc_escape(const char **end, const char **start, int *sz)
 		}
 		break;
 	case (ESCAPE_SPECIAL):
-		if (1 != rlim)
-			break;
-		if ('c' == *rstart)
+		if (1 == *sz && 'c' == **start)
 			gly = ESCAPE_NOSPACE;
 		break;
 	default: