Introduce a basic c-mode to mg.

The intent of this mode is NOT to copy emacs's monster cc-mode.
It is intended to handle basic KNF-format C, assisting
with indentation (to catch obvious typos), and strip
trailing whitespace. It is NOT enabled unless you ask for it (c-mode).

Basically, tab on start-of-line whitespace acts like tab.
Otherwise, tab indents.

Please try it out and let me know where it falls down.

Feedback Reyk, phessler. "hack in tree" from henning, theo

4 files changed, 339 insertions, 4 deletions

diff --git a/usr.bin/mg/Makefile b/usr.bin/mg/Makefile
index 2af8c742be7..8b610342043 100644
--- a/usr.bin/mg/Makefile
+++ b/usr.bin/mg/Makefile
@@ -1,4 +1,4 @@
-# $OpenBSD: Makefile,v 1.19 2006/12/16 17:00:03 kjell Exp $
+# $OpenBSD: Makefile,v 1.20 2008/06/12 01:58:44 kjell Exp $
 
 PROG=	mg
 
@@ -25,6 +25,6 @@ SRCS=	cinfo.c fileio.c spawn.c ttyio.c tty.c ttykbd.c \
 #
 # More or less standalone extensions.
 #
-SRCS+=	grep.c theo.c mail.c
+SRCS+=	grep.c theo.c mail.c cmode.c
 
 .include <bsd.prog.mk>
diff --git a/usr.bin/mg/cmode.c b/usr.bin/mg/cmode.c
new file mode 100644
index 00000000000..e2660f96337
--- /dev/null
+++ b/usr.bin/mg/cmode.c
@@ -0,0 +1,327 @@
+/* $OpenBSD: cmode.c,v 1.1 2008/06/12 01:58:44 kjell Exp $ */
+/*
+ * This file is in the public domain.
+ *
+ * Author: Kjell Wooding <kjell@openbsd.org>
+ */
+
+/*
+ * Implement an non-irritating KNF-compliant mode for editing
+ * C code.
+ */
+#include <ctype.h>
+
+#include "def.h"
+#include "kbd.h"
+#include "funmap.h"
+
+/* Pull in from modes.c */
+extern int changemode(int, int, char *);
+
+static int cc_strip_trailp = TRUE;	/* Delete Trailing space? */
+static int cc_basic_indent = 8;		/* Basic Indent multiple */
+static int cc_cont_indent = 4;		/* Continued line indent */
+static int cc_colon_indent = -8;	/* Label / case indent */
+
+static int getmatch(int, int);
+static int getindent(const struct line *, int *);
+
+/* Keymaps */
+
+static PF cmode_brace[] = {
+	cc_char,	/* } */
+};
+
+static PF cmode_ci[] = {
+	cc_tab,		/* ^I */
+	rescan,		/* ^J */
+	rescan,		/* ^K */
+	rescan,		/* ^L */
+	cc_lfindent,	/* ^M */
+};
+
+static PF cmode_colon[] = {
+	cc_char,	/* : */
+	rescan,		/* ; */
+};
+
+static struct KEYMAPE (3 + IMAPEXT) cmodemap = {
+	3,
+	3 + IMAPEXT,
+	rescan,
+	{
+		{ CCHR('I'), CCHR('M'), cmode_ci, NULL },
+		{ ':', ';', cmode_colon, NULL },
+		{ '}', '}', cmode_brace, NULL }
+	}
+};
+
+/* Funtion, Mode hooks */
+
+void
+cmode_init(void)
+{
+	funmap_add(cmode, "c-mode");
+	funmap_add(cc_char, "c-handle-special-char");
+	funmap_add(cc_tab, "c-tab-or-indent");
+	funmap_add(cc_indent, "c-indent");
+	funmap_add(cc_lfindent, "c-indent-and-newline");
+	maps_add((KEYMAP *)&cmodemap, "c-mode");
+}
+
+/*
+ * Enable/toggle c-mode
+ */
+int
+cmode(int f, int n)
+{
+	return(changemode(f, n, "c-mode"));
+}
+
+/*
+ * Handle special C character - selfinsert then indent.
+ */
+int
+cc_char(int f, int n)
+{
+	if (n < 0)
+		return (FALSE);
+	if (selfinsert(FFRAND, n) == FALSE)
+		return (FALSE);
+	return (cc_indent(FFRAND, n));
+}
+
+/*
+ * If we are in the whitespace at the beginning of the line,
+ * simply act as a regular tab. If we are not, indent
+ * current line according to whitespace rules.
+ */
+int
+cc_tab(int f, int n)
+{
+	int lo;
+	int inwhitep = FALSE;	/* In leading whitespace? */
+	
+	for (lo = 0; lo < llength(curwp->w_dotp); lo++) {
+		if (!isspace(lgetc(curwp->w_dotp, lo)))
+			break;
+		if (lo == curwp->w_doto)
+			inwhitep = TRUE;
+	}
+
+	/* Special case: we could be at the end of a whitespace line */
+	if (lo == llength(curwp->w_dotp) && curwp->w_doto == lo)
+		inwhitep = TRUE;
+	
+	/* If empty line, or in whitespace */
+	if (llength(curwp->w_dotp) == 0 || inwhitep)
+		return (selfinsert(f, n));
+
+	return (cc_indent(FFRAND, 1));
+}
+
+/*
+ * Attempt to indent current line according to KNF rules.
+ */
+int
+cc_indent(int f, int n)
+{
+	int pi, mi;			/* Previous indents */
+	int ci, dci;			/* current indent, don't care */
+	int lo;
+	int c;
+	int nonblankp;
+	struct line *lp;
+
+	if (n < 0)
+		return (FALSE);
+
+	if (cc_strip_trailp)
+		deltrailwhite(FFRAND, 1);
+
+	/* Search backwards for a nonblank, non preprocessor line */
+	lp = curwp->w_dotp;
+	nonblankp = FALSE;
+	while (lback(lp) != curbp->b_headp && !nonblankp) {
+		lp = lback(lp);
+		for (lo = 0; lo < llength(lp); lo++) {
+			if (!isspace(c = lgetc(lp, lo))) {
+				/* Leading # is a blank */
+				if (c != '#')	
+					nonblankp = TRUE;
+				break;
+			}
+		}
+	}
+
+	pi = getindent(lp, &mi);
+
+	/* Strip leading space on current line */
+	delleadwhite(FFRAND, 1);
+	/* current indent is computed only to current position */
+	dci = getindent(curwp->w_dotp, &ci);
+	
+	if (pi + ci < 0)
+		return(indent(FFOTHARG, 0));
+	else
+		return(indent(FFOTHARG, pi + ci));
+}
+
+/*
+ * Indent-and-newline (technically, newline then indent)
+ */
+int
+cc_lfindent(int f, int n)
+{
+	if (n < 0)
+		return (FALSE);
+	if (newline(FFRAND, 1) == FALSE)
+		return (FALSE);
+	return (cc_indent(FFRAND, n));
+}
+
+/*
+ * Get the level of indention after line lp is processed
+ * Note getindent has two returns: curi, nexti.
+ * curi = value if indenting current line.
+ * return value = value affecting subsequent lines.
+ * note, we only process up to offset op.
+ * set to llength(lp) for the whole line.
+ */
+static int
+getindent(const struct line *lp, int *curi)
+{
+	int lo, co;		/* leading space,  current offset*/
+	int nicol = 0;		/* position count */
+	int c = '\0';		/* current char */
+	int newind = 0;		/* new index value */
+	int stringp = FALSE;	/* in string? */
+	int escp = FALSE;	/* Escape char? */
+	int lastc = '\0';	/* Last matched string delimeter */
+	int nparen = 0;		/* paren count */
+	int obrace = 0;		/* open brace count */
+	int cbrace = 0;		/* close brace count */
+	int contp = FALSE;	/* Continue? */
+	int firstseenp = FALSE;	/* First nonspace encountered? */
+	int colonp = FALSE;	/* Did we see a colon? */
+	int questionp = FALSE;	/* Did we see a question mark? */
+	
+	*curi = 0;
+
+	/* Compute leading space */
+	for (lo = 0; lo < llength(lp); lo++) {
+		if (!isspace(c = lgetc(lp, lo)))
+			break;
+		if (c == '\t'
+#ifdef NOTAB
+		    && !(curbp-b_flag & BFNOTAB)
+#endif /* NOTAB */
+		    ) {
+			nicol |= 0x07;
+		}
+		nicol++;
+	}
+
+	/* If last line was blank, choose 0 */
+	if (lo == llength(lp))
+		nicol = 0;
+
+	if (c == '#')
+		return (0);
+
+	newind = 0;
+	/* Compute modifiers */
+	for (co = lo; co < llength(lp); co++) {
+		c = lgetc(lp, co);
+		/* We have a non-whitespace char */
+		if (!firstseenp && !isspace(c)) {
+			contp = TRUE;
+			firstseenp = TRUE; 
+		}
+		if (c == '\\')
+			escp = !escp;
+		else if (stringp) {
+			if (!escp && (c == '"' || c == '\'')) {
+				/* unescaped string char */
+				if (getmatch(c, lastc))
+					stringp = FALSE;
+			}
+		} else if (c == '"' || c == '\'') {
+			stringp = TRUE;
+			lastc = c;
+		} else if (c == '(') {
+			nparen++;
+		} else if (c == ')') {
+			nparen--;
+		} else if (c == '{') {
+			obrace++;
+			firstseenp = FALSE;
+			contp = FALSE;
+		} else if (c == '}') {
+			cbrace++;
+		} else if (c == '?') {
+			questionp = TRUE;
+		} else if (c == ':') {
+			/* ignore (foo ? bar : baz) construct */
+			if (!questionp)
+				colonp = TRUE;
+		} else if (c == ';') {
+			if (nparen > 0)
+				contp = FALSE;
+		}
+
+		/* Reset escape character match */
+		if (c != '\\')
+			escp = FALSE;
+	}
+	/*
+	 * If not terminated with a semicolon, and brace or paren open.
+	 * we continue
+	 */
+	if (colonp) {
+		*curi += cc_colon_indent;
+		newind -= cc_colon_indent;
+	}
+
+	*curi -= (cbrace) * cc_basic_indent;
+	newind += obrace * cc_basic_indent;
+
+	if (nparen < 0)
+		newind -= cc_cont_indent;
+	else if (nparen > 0)
+		newind += cc_cont_indent;
+	newind += nicol;
+	*curi += nicol;
+
+	return (newind);
+}
+
+/*
+ * Given a delimeter and its purported mate, tell us if they
+ * match.
+ */
+static int
+getmatch(int c, int mc)
+{
+	int match = FALSE;
+
+	switch (c) {
+	case '"':
+		match = (mc == '"');
+		break;
+	case '\'':
+		match = (mc == '\'');
+		break;
+	case '(':
+		match = (mc == ')');
+		break;
+	case '[':
+		match = (mc == ']');
+		break;
+	case '{':
+		match = (mc == '}');
+		break;
+	}
+
+	return (match);
+}
diff --git a/usr.bin/mg/def.h b/usr.bin/mg/def.h
index 0aa9de7b4b2..da4e15853a1 100644
--- a/usr.bin/mg/def.h
+++ b/usr.bin/mg/def.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: def.h,v 1.102 2008/06/11 23:18:33 kjell Exp $	*/
+/*	$OpenBSD: def.h,v 1.103 2008/06/12 01:58:44 kjell Exp $	*/
 
 /* This file is in the public domain. */
 
@@ -620,6 +620,12 @@ int		 add_autoexec(const char *, const char *);
 
 /* mail.c X */
 void		 mail_init(void);
+/* cmode.c X */
+int		 cmode(int, int);
+int		 cc_char(int, int);
+int		 cc_tab(int, int);
+int		 cc_indent(int, int);
+int		 cc_lfindent(int, int);
 
 /* grep.c X */
 int		 next_error(int, int);
diff --git a/usr.bin/mg/main.c b/usr.bin/mg/main.c
index 2238a39757a..b67c08b53ad 100644
--- a/usr.bin/mg/main.c
+++ b/usr.bin/mg/main.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: main.c,v 1.57 2008/05/29 19:58:15 sobrado Exp $	*/
+/*	$OpenBSD: main.c,v 1.58 2008/06/12 01:58:44 kjell Exp $	*/
 
 /* This file is in the public domain. */
 
@@ -75,12 +75,14 @@ main(int argc, char **argv)
 		extern void grep_init(void);
 		extern void theo_init(void);
 		extern void mail_init(void);
+		extern void cmode_init(void);
 		extern void dired_init(void);
 
 		dired_init();
 		grep_init();
 		theo_init();
 		mail_init();
+		cmode_init();
 	}
 
 	if (init_fcn_name &&