full split complete

+ editor removes per-buffer fields.
+ switching from internal use of 'int' to 'size_t'.
+ deleting old code
+ double checking relevancy of comments. A lot has changed in
  5 years, even more so in the past week.
+ fixing a few vestigal memory errors from the overhaul.
+ fixing search behavior

CMakeLists.txt

@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.15)
 project(ke C)  # Specify C language explicitly
 
 set(CMAKE_C_STANDARD 99)
-set(KE_VERSION "1.3.3")
+set(KE_VERSION "2.1.1")
 
 set(CMAKE_C_FLAGS "-Wall -Wextra -pedantic -Wshadow -Werror -std=c99 -g")
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -D_DEFAULT_SOURCE -D_XOPEN_SOURCE")
@@ -19,8 +19,34 @@ endif()
 
 include(GNUInstallDirs)
 
+set(SOURCES
+        abuf.c
+        core.c
+        term.c
+        buffer.c
+        editor.c
+        editing.c
+        killring.c
+        process.c
+        undo.c
+        main.c
+)
+
+set(HEADERS
+        abuf.h
+        core.h
+        term.h
+        buffer.h
+        editor.h
+        editing.h
+        killring.h
+        process.h
+        undo.h
+)
+
+
 # Add executable
-add_executable(ke main.c)
+add_executable(ke ${SOURCES} ${HEADERS})
 target_compile_definitions(ke PRIVATE KE_VERSION="ke version ${KE_VERSION}")
 install(TARGETS ke RUNTIME DESTINATION bin)
 install(FILES ke.1 TYPE MAN)

Makefile

@@ -11,8 +11,13 @@ LDFLAGS :=	-fsanitize=address
 
 all: $(TARGET) test.txt
 
-$(TARGET): main.c
-	$(CC) $(CFLAGS) -o $(TARGET) $(LDFLAGS) main.c
+SRCS := main.c abuf.c core.c term.c buffer.c editor.c editing.c killring.c \
+	       process.c undo.c
+HDRS :=        abuf.h core.h term.h buffer.h editor.h editing.c killring.h \
+	       process.h undo.h
+
+$(TARGET): $(SRCS)
+	$(CC) $(CFLAGS) -o $(TARGET) $(SRCS) $(LDFLAGS)
 
 .PHONY: install
 #install: $(TARGET) 
@@ -26,3 +31,12 @@ clean:
 .PHONY: test.txt
 test.txt:
 	cp test.txt.bak $@
+
+.PHONY: gdb
+gdb:
+	@test -f $(TARGET).pid || (echo "error: $(TARGET).pid not found" >&2; exit 1)
+	@gdb -p $$(cat $(TARGET).pid | tr -d ' \t\n\r') ./$(TARGET)
+
+.PHONY: cloc
+cloc:
+	cloc $(SRCS) $(HDRS)

README.txt

@@ -16,3 +16,9 @@ To get verbose ASAN messages:
     export LSAN_OPTIONS=verbosity=1:log_threads=1
 
 Released under an ISC license.
+
+Started by following along with kilo:
+    https://viewsourcecode.org/snaptoken/kilo/
+
+E.g., in the devlogs
+    https://log.wntrmute.dev/2020/02/20200207

TODO

@@ -1,15 +1,18 @@
 [X] goto-line
 [X] text-corruption bug
 [ ] alt-modifiers
-[ ] refresh-screen
-[ ] functions -> keymapping?
+[x] refresh-screen
+[ ] functions -> keymapping? (what did this even mean)
 [X] rendering: need to skip over control characters like we do with tabs
 [X] control-d -> delete
-[ ] control-g -> exit buf prompt
-[ ] load-file prompt on dirty buffer
+[x] control-g -> exit buf prompt
+[x] load-file prompt on dirty buffer
 [ ] multiple files
+[x] utf-8
+[x] kill ring
+[x] mark/region
 
 What would it take for ke to be your daily drives?
-+ C-u
-+ Alt nav (backspace, delete, f, b, etc)
-
+[x] C-u (repeat actions)
+[x] Alt nav (backspace, delete, f, b, etc)
+[-] undo tree (C-k u/U)

abuf.c

@@ -0,0 +1,131 @@
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "abuf.h"
+#include "core.h"
+
+
+static void
+abuf_grow(abuf *buf, size_t delta)
+{
+	if (buf->cap - buf->size < delta) {
+		ab_resize(buf, buf->cap + delta);
+	}
+}
+
+
+void
+ab_init(abuf *buf)
+{
+	assert(buf != NULL);
+
+	buf->b    = NULL;
+	buf->size = buf->cap = 0;
+}
+
+
+void
+ab_init_cap(abuf *buf, const size_t cap)
+{
+	ab_init(buf);
+
+	if (cap > 0) {
+		ab_resize(buf, cap);
+	}
+}
+
+
+void
+ab_resize(abuf *buf, size_t cap)
+{
+	char	*newbuf = NULL;
+
+	cap = cap_growth(buf->cap, cap) + 1;
+	newbuf = realloc(buf->b, cap);
+	assert(newbuf != NULL);
+	buf->cap = cap;
+	buf->b   = newbuf;
+}
+
+
+void
+ab_appendch(abuf *buf, char c)
+{
+	abuf_grow(buf, 1);
+	ab_append(buf, &c, 1);
+}
+
+
+void
+ab_append(abuf *buf, const char *s, size_t len)
+{
+	char	*nc = NULL;
+
+	abuf_grow(buf, len);
+	nc = buf->b;
+
+	memcpy(&nc[buf->size], s, len);
+	buf->b = nc;
+	buf->size += len;
+}
+
+
+void
+ab_append_ab(abuf *buf, const abuf *other)
+{
+	assert(buf != NULL);
+	if (other == NULL) {
+		return;
+	}
+
+	ab_append(buf, other->b, other->size);
+}
+
+
+void
+ab_prependch(abuf *buf, const char c)
+{
+	abuf_grow(buf, 1);
+
+	ab_prepend(buf, &c, 1);
+}
+
+
+void
+ab_prepend(abuf *buf, const char *s, const size_t len)
+{
+	char	*nc = NULL;
+
+	abuf_grow(buf, len);
+	nc = buf->b;
+	assert(nc != NULL);
+
+	memmove(nc + len, nc, buf->size);
+	memcpy(nc, s, len);
+
+	buf->b = nc;
+	buf->size += len;
+}
+
+
+void
+ab_prepend_ab(abuf *buf, const abuf *other)
+{
+	assert(buf != NULL);
+	if (other == NULL) {
+		return;
+	}
+
+	ab_prepend(buf, other->b, other->size);
+}
+
+
+void
+ab_free(abuf *buf)
+{
+	free(buf->b);
+	buf->b    = NULL;
+	buf->size = 0;
+	buf->cap  = 0;
+}

abuf.h

@@ -0,0 +1,32 @@
+/*
+ * abuf.h - append/prepend buffer utilities
+ */
+#ifndef KE_ABUF_H
+#define KE_ABUF_H
+
+#include <stddef.h>
+
+
+typedef struct abuf {
+    char	*b;
+    size_t	 size;
+    size_t	 cap;
+} abuf;
+
+
+#define ABUF_INIT {NULL, 0, 0}
+
+
+void		 ab_init(abuf *buf);
+void		 ab_init_cap(abuf *buf, size_t cap);
+void		 ab_resize(abuf *buf, size_t cap);
+void		 ab_appendch(abuf *buf, char c);
+void		 ab_append(abuf *buf, const char *s, size_t len);
+void		 ab_append_ab(abuf *buf, const abuf *other);
+void		 ab_prependch(abuf *buf, const char c);
+void		 ab_prepend(abuf *buf, const char *s, const size_t len);
+void		 ab_prepend_ab(abuf *buf, const abuf *other);
+void		 ab_free(abuf *buf);
+
+
+#endif

buffer.c

@@ -0,0 +1,463 @@
+/* buffer.c - multiple file buffers */
+
+#include <assert.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "abuf.h"
+#include "buffer.h"
+#include "core.h"
+#include "editor.h"
+
+
+#define		NO_NAME		 "[No Name]"
+
+
+/* externs from other modules */
+char *editor_prompt(const char *, void (*cb)(char *, int16_t));
+
+
+static const char *
+buf_basename(const char *path)
+{
+	if (path == NULL) {
+		return NULL;
+	}
+
+	const char *slash = strrchr(path, '/');
+	return (slash != NULL) ? (slash + 1) : path;
+}
+
+
+static int
+buffer_find_exact_by_name(const char *name)
+{
+	buffer	*b = NULL;
+	size_t   i = 0;
+
+	if (name == NULL) {
+		return -1;
+	}
+
+	for (i = 0; i < editor.bufcount; i++) {
+		b                = editor.buffers[i];
+		const char *full = b->filename;
+		const char *base = buf_basename(full);
+
+		if (full && strcmp(full, name) == 0) {
+			return i;
+		}
+
+		if (base && strcmp(base, name) == 0) {
+			return i;
+		}
+
+		if (full == NULL && strcmp(name, NO_NAME) == 0) {
+			return i;
+		}
+	}
+
+	return -1;
+}
+
+
+static int
+buffer_collect_prefix_matches(const char *prefix, int *out_idx, const int max_out)
+{
+	buffer	*b       = NULL;
+	int      count   = 0;
+	int      matched = 0;
+	size_t   i       = 0;
+	size_t	 plen    = (prefix ? strlen(prefix) : 0);
+
+	for (i = 0; i < editor.bufcount; i++) {
+		matched = 0;
+		b = editor.buffers[i];
+
+		const char *cand1 = b->filename;
+		const char *cand2 = buf_basename(cand1);
+
+		if (plen == 0) {
+			matched = 1; /* everything matches empty prefix */
+		} else {
+			if (cand2 && strncmp(cand2, prefix, plen) == 0) {
+				matched = 1;
+			} else if (cand1 && strncmp(cand1, prefix, plen) == 0) {
+				matched = 1;
+			} else if (!cand1 && strncmp(NO_NAME, prefix, plen) == 0) {
+				matched = 1;
+			}
+		}
+
+		if (matched) {
+			if (count < max_out) {
+				out_idx[count] = i;
+			}
+			count++;
+		}
+	}
+
+	return count;
+}
+
+
+static void
+longest_common_prefix(char *buf, const size_t bufsz, const int *idxs, const int n)
+{
+	const char *first = NULL;
+	const char *cand  = NULL;
+	int k             = 0;
+	size_t j          = 0;
+	size_t cur        = 0;
+	size_t lcp        = 0;
+	size_t to_copy    = 0;
+
+	if (n <= 0) {
+		return;
+	}
+
+	first = buf_basename(editor.buffers[idxs[0]]->filename);
+	if (first == NULL) {
+		first = NO_NAME;
+	}
+
+	lcp = strnlen(first, FILENAME_MAX);
+	for (k = 1; k < n; k++) {
+		cand = buf_basename(editor.buffers[idxs[k]]->filename);
+		if (cand == NULL) {
+			cand = NO_NAME;
+		}
+
+		j = 0;
+		while (j < lcp && first[j] == cand[j]) {
+			j++;
+		}
+
+		lcp = j;
+		if (lcp == 0) {
+			break;
+		}
+	}
+
+	cur = strlen(buf);
+	if (lcp > cur) {
+		to_copy = lcp - cur;
+		if (cur + to_copy >= bufsz) {
+			to_copy = bufsz - cur - 1;
+		}
+
+		strncat(buf, first + cur, to_copy);
+	}
+}
+
+
+static void
+buffer_switch_prompt_cb(char *buf, const int16_t key)
+{
+	char msg[80]     = {0};
+	const char *name = NULL;
+	const char *nm   = NULL;
+	int idxs[64]     = {0};
+	int n            = 0;
+	size_t need      = 0;
+	size_t used      = 0;
+
+	if (key != TAB_KEY) {
+		return;
+	}
+
+	n = buffer_collect_prefix_matches(buf, idxs, 64);
+	if (n <= 0) {
+		editor_set_status("No matches");
+		return;
+	}
+
+	if (n == 1) {
+		name = buf_basename(editor.buffers[idxs[0]]->filename);
+		if (name == NULL) {
+			name = NO_NAME;
+		}
+
+		need = strlen(name);
+		if (need < 128) {
+			memcpy(buf, name, need);
+			buf[need] = '\0';
+		}
+
+		editor_set_status("Unique match: %s", name);
+		return;
+	}
+
+	longest_common_prefix(buf, 128, idxs, n);
+	msg[0] = '\0';
+	used   = 0;
+	used += snprintf(msg + used, sizeof(msg) - used, "%d matches: ", n);
+	for (int i = 0; i < n && used < sizeof(msg) - 1; i++) {
+		nm = buf_basename(editor.buffers[idxs[i]]->filename);
+		if (nm == NULL) {
+			nm = NO_NAME;
+		}
+
+		used += snprintf(msg + used, sizeof(msg) - used, "%s%s",
+		                 nm, (i == n - 1 ? "" : ", "));
+	}
+
+	editor_set_status("%s", msg);
+}
+
+
+const char *
+buffer_name(buffer *b)
+{
+	if (b && b->filename) {
+		return buf_basename(b->filename);
+	}
+
+	return NO_NAME;
+}
+
+
+void
+buffers_init(void)
+{
+	int	 idx = 0;
+
+	editor.buffers  = NULL;
+	editor.bufcount = 0;
+	editor.curbuf   = 0;
+	editor.bufcap	= 0;
+
+	idx = buffer_add_empty();
+	buffer_switch(idx);
+}
+
+
+static void
+buffer_list_resize(void)
+{
+	buffer	**newlist = NULL;
+
+	if (editor.bufcount == editor.bufcap) {
+		editor.bufcap = (size_t)cap_growth((int)editor.bufcap,
+			(int)editor.bufcount + 1);
+
+		newlist = realloc(editor.buffers, sizeof(buffer *) * editor.bufcap);
+		assert(newlist != NULL);
+		editor.buffers = newlist;
+	}
+}
+
+
+int
+buffer_add_empty(void)
+{
+	buffer	 *buf    = NULL;
+	int	 idx     = 0;
+
+	buffer_list_resize();
+
+	buf = calloc(1, sizeof(buffer));
+	assert(buf != NULL);
+
+	buf->curx      = 0;
+	buf->cury      = 0;
+	buf->rx        = 0;
+	buf->nrows     = 0;
+	buf->rowoffs   = 0;
+	buf->coloffs   = 0;
+	buf->row       = NULL;
+	buf->filename  = NULL;
+	buf->dirty     = 0;
+	buf->mark_set  = 0;
+	buf->mark_curx = 0;
+	buf->mark_cury = 0;
+
+	undo_tree_init(&buf->undo);
+
+	editor.buffers[editor.bufcount] = buf;
+	idx                             = (int)editor.bufcount;
+	editor.bufcount++;
+	return idx;
+}
+
+
+buffer *
+buffer_current(void)
+{
+	if (editor.bufcount == 0 || editor.curbuf >= editor.bufcount) {
+		return NULL;
+	}
+
+	return editor.buffers[editor.curbuf];
+}
+
+
+int
+buffer_is_unnamed_and_empty(const buffer *b)
+{
+	if (b == NULL) {
+		return 0;
+	}
+
+	if (b->filename != NULL) {
+		return 0;
+	}
+
+	if (b->dirty) {
+		return 0;
+	}
+
+	if (b->nrows != 0) {
+		return 0;
+	}
+
+	if (b->row != NULL) {
+		return 0;
+	}
+
+	return 1;
+}
+
+
+void
+buffer_switch(const int idx)
+{
+	buffer	*b = NULL;
+
+	if (idx < 0 || (size_t)idx >= editor.bufcount) {
+		return;
+	}
+
+	if (editor.curbuf == (size_t)idx) {
+		return;
+	}
+
+	b = editor.buffers[idx];
+	editor.curbuf  = (size_t)idx;
+	editor.dirtyex = 1;
+	editor_set_status("Switched to buffer %d: %s", editor.curbuf, buffer_name(b));
+}
+
+
+void
+buffer_next(void)
+{
+	size_t idx = 0;
+	
+	if (editor.bufcount <= 1) {
+		return;
+	}
+	
+	idx = (editor.curbuf + 1) % editor.bufcount;
+	buffer_switch((int)idx);
+}
+
+
+void
+buffer_prev(void)
+{
+	size_t	 idx = 0;
+	
+	if (editor.bufcount <= 1) {
+		return;
+	}
+	
+	idx = (editor.curbuf == 0) ? (editor.bufcount - 1) : (editor.curbuf - 1);
+	buffer_switch((int)idx);
+}
+
+
+void
+buffer_close_current(void)
+{
+	buffer	*b   = NULL;
+	size_t	 closing = 0;
+	int	 target  = 0;
+	int	 nb      = 0;
+
+	/* sanity check */
+	if (editor.bufcount == 0 || editor.curbuf >= editor.bufcount) {
+		editor_set_status("No buffer to close.");
+		return;
+	}
+
+	closing = editor.curbuf;
+
+	if (editor.bufcount > 1) {
+		target = (closing > 0) ? (int) (closing - 1) : (int) (closing + 1);
+		buffer_switch(target);
+	} else {
+		nb = buffer_add_empty();
+		buffer_switch(nb);
+	}
+
+	b = editor.buffers[closing];
+	if (b) {
+		if (b->row) {
+			for (size_t i = 0; i < b->nrows; i++) {
+				ab_free(&b->row[i]);
+			}
+			free(b->row);
+		}
+
+		if (b->filename) {
+			free(b->filename);
+		}
+		free(b);
+	}
+
+	memmove(&editor.buffers[closing], &editor.buffers[closing + 1],
+		sizeof(buffer *) * (editor.bufcount - closing - 1));
+
+	editor.bufcount--;
+	if (editor.bufcount == 0) {
+		editor.curbuf = 0;
+	} else {
+		if (editor.curbuf > closing) {
+			editor.curbuf--;
+		}
+	}
+
+	editor.dirtyex = 1;
+	editor_set_status("Closed buffer. Now on %s",
+			  buffer_name(editor.buffers[editor.curbuf]));
+}
+
+
+void
+buffer_switch_by_name(void)
+{
+	int	 idxs[64] = {0};
+	char	*name   = NULL;
+	int	 idx      = 0;
+	int	 n        = 0;
+
+	if (editor.bufcount <= 1) {
+		editor_set_status("No other buffers.");
+		return;
+	}
+
+	name = editor_prompt("Switch buffer (name, TAB to complete): %s", buffer_switch_prompt_cb);
+	if (name == NULL) {
+		return;
+	}
+
+	idx = buffer_find_exact_by_name(name);
+	if (idx < 0) {
+		n = buffer_collect_prefix_matches(name, idxs, 64);
+		if (n == 1) {
+			idx = idxs[0];
+		}
+	}
+
+	if (idx >= 0) {
+		buffer_switch(idx);
+	} else {
+		editor_set_status("No open buffer: %s", name);
+	}
+
+	free(name);
+}
+

buffer.h

@@ -0,0 +1,50 @@
+#ifndef KE_BUFFER_H
+#define KE_BUFFER_H
+
+#include "abuf.h"
+#include "undo.h"
+
+
+typedef struct buffer {
+	size_t		 curx, cury;
+	size_t		 rx;
+	size_t		 nrows;
+	size_t		 rowoffs, coloffs;
+	abuf		*row;
+	char		*filename;
+	int		 dirty;
+	int		 mark_set;
+	size_t		 mark_curx, mark_cury;
+	undo_tree	 undo;
+} buffer;
+
+
+buffer				*buffer_current(void);
+#define CURBUF			(buffer_current())
+#define EROW			(CURBUF->row)
+#define ENROWS			(CURBUF->nrows)
+#define ECURX			(CURBUF->curx)
+#define ECURY			(CURBUF->cury)
+#define ERX			(CURBUF->rx)
+#define EROWOFFS		(CURBUF->rowoffs)
+#define ECOLOFFS		(CURBUF->coloffs)
+#define EFILENAME		(CURBUF->filename)
+#define EDIRTY			(CURBUF->dirty)
+#define EMARK_SET		(CURBUF->mark_set)
+#define EMARK_CURX		(CURBUF->mark_curx)
+#define EMARK_CURY		(CURBUF->mark_cury)
+
+
+void		 buffers_init(void);
+int		 buffer_add_empty(void);
+void		 buffer_save_current(void);
+void		 buffer_switch(int idx);
+void		 buffer_next(void);
+void		 buffer_prev(void);
+void		 buffer_switch_by_name(void);
+void		 buffer_close_current(void);
+const char	*buffer_name(buffer *b);
+int		 buffer_is_unnamed_and_empty(const buffer *b);
+
+
+#endif

core.c

@@ -0,0 +1,151 @@
+#include <sys/stat.h>
+#include <assert.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "core.h"
+
+
+#ifdef	INCLUDE_STRNSTR
+
+/*
+ * Find the first occurrence of find in s, where the search is limited to the
+ * first slen characters of s.
+ */
+char *
+strnstr(const char *s, const char *find, size_t slen)
+{
+	char	 c, sc;
+	size_t	 len;
+
+	if ((c = *find++) != '\0') {
+		len = strlen(find);
+		do {
+			do {
+				if (slen-- < 1 || (sc = *s++) == '\0')
+					return (NULL);
+			} while (sc != c);
+			if (len > slen)
+				return (NULL);
+		} while (strncmp(s, find, len) != 0);
+		s--;
+	}
+	return ((char*)s);
+}
+#endif
+
+
+int
+path_is_dir(const char *path)
+{
+	struct stat st;
+
+	if (path == NULL) {
+		return 0;
+	}
+
+	if (stat(path, &st) == 0) {
+		return S_ISDIR(st.st_mode);
+	}
+
+	return 0;
+}
+
+
+size_t
+str_lcp2(const char *a, const char *b)
+{
+	size_t	 i = 0;
+
+	if (!a || !b) {
+		return 0;
+	}
+
+	while (a[i] && b[i] && a[i] == b[i]) {
+		i++;
+	}
+
+	return i;
+}
+
+
+void
+swap_size_t(size_t *first, size_t *second)
+{
+	*first ^= *second;
+	*second ^= *first;
+	*first ^= *second;
+}
+
+
+int
+next_power_of_2(int n)
+{
+	if (n < 2) {
+		n = 2;
+	}
+
+	n--;
+	n |= n >> 1;
+	n |= n >> 2;
+	n |= n >> 4;
+	n |= n >> 8;
+	n |= n >> 16;
+
+	return n + 1;
+}
+
+
+int
+cap_growth(int cap, int sz)
+{
+	if (cap == 0) {
+		cap = INITIAL_CAPACITY;
+	}
+
+	while (cap <= sz) {
+		cap = next_power_of_2(cap + 1);
+	}
+
+	return cap;
+}
+
+
+size_t
+kstrnlen(const char *buf, const size_t max)
+{
+	if (buf == NULL) {
+		return 0;
+	}
+
+	return strnlen(buf, max);
+}
+
+
+void
+kwrite(const int fd, const char* buf, const int len)
+{
+	int wlen = 0;
+
+	wlen = write(fd, buf, len);
+	assert(wlen != -1);
+	assert(wlen == len);
+	if (wlen == -1) {
+		abort();
+	}
+}
+
+
+void
+die(const char* s)
+{
+	kwrite(STDOUT_FILENO, "\x1b[2J", 4);
+	kwrite(STDOUT_FILENO, "\x1b[H", 3);
+
+	perror(s);
+	exit(1);
+}
+

core.h

@@ -0,0 +1,52 @@
+#ifndef KE_CORE_H
+#define KE_CORE_H
+
+#include <stddef.h>
+
+
+#ifndef KE_VERSION
+#define KE_VERSION		"ke dev build"
+#endif
+
+
+#define ESCSEQ			"\x1b["
+#define	CTRL_KEY(key)		((key)&0x1f)
+#define TAB_STOP		8
+#define MSG_TIMEO		3
+
+#define	TAB_STOP		8
+#define	INITIAL_CAPACITY	8
+
+
+typedef enum key_press {
+	TAB_KEY     = 9,
+	ESC_KEY     = 27,
+	BACKSPACE   = 127,
+	ARROW_LEFT  = 1000,
+	ARROW_RIGHT = 1001,
+	ARROW_UP    = 1002,
+	ARROW_DOWN  = 1003,
+	DEL_KEY     = 1004,
+	HOME_KEY    = 1005,
+	END_KEY     = 1006,
+	PG_UP       = 1007,
+	PG_DN       = 1008,
+} key_press;
+
+
+#ifndef strnstr
+char	*strnstr(const char *s, const char *find, size_t slen);
+#define	INCLUDE_STRNSTR
+#endif
+
+int		 path_is_dir(const char *path);
+size_t		 str_lcp2(const char *a, const char *b);
+void		 swap_size_t(size_t *first, size_t *second);
+int 		 next_power_of_2(int n);
+int 		 cap_growth(int cap, int sz);
+size_t		 kstrnlen(const char *buf, size_t max);
+void		 kwrite(int fd, const char *buf, int len);
+void		 die(const char *s);
+
+
+#endif

default.nix

@@ -1,16 +1,31 @@
 {
   lib,
-  installShellFiles,
   stdenv,
+  cmake,
+  installShellFiles,
   ...
 }:
+let
+  cmakeContent = builtins.readFile ./CMakeLists.txt;
+  cmakeLines = lib.splitString "\n" cmakeContent;
+  versionLine = lib.findFirst (l: builtins.match ".*set\\(KE_VERSION \".+\"\\).*" l != null) (throw "KE_VERSION not found in CMakeLists.txt") cmakeLines;
+  version = builtins.head (builtins.match ".*set\\(KE_VERSION \"(.+)\"\\).*" versionLine);
+in
 stdenv.mkDerivation {
   pname = "ke";
-  version = "1.3.3";
+  inherit version;
 
   src = lib.cleanSource ./.;
 
-  nativeBuildInputs = [ installShellFiles ];
+  nativeBuildInputs = [
+    cmake
+    installShellFiles
+  ];
+
+  cmakeFlags = [
+    "-DENABLE_ASAN=on"
+    "-DCMAKE_BUILD_TYPE=Debug"
+  ];
 
   installPhase = ''
     runHook preInstall
@@ -18,10 +33,8 @@ stdenv.mkDerivation {
     mkdir -p $out/bin
     cp ke $out/bin/
 
+    installManPage ../ke.1
+
     runHook postInstall
   '';
-
-  postInstall = ''
-    installManPage ke.1
-  '';
 }

editing.h

@@ -0,0 +1,50 @@
+#ifndef KE_EDITING_H
+#define KE_EDITING_H
+
+#include <stdint.h>
+
+#include "abuf.h"
+
+
+/* miscellaneous */
+void		 file_open_prompt_cb(char *buf, int16_t key);
+int		 erow_render_to_cursor(const abuf *row, int cx);
+int		 erow_cursor_to_render(abuf *row, int rx);
+int		 erow_init(abuf *row, int len);
+void		 erow_insert(int at, char *s, int len);
+void		 jump_to_position(size_t col, size_t row);
+void		 goto_line(void);
+int	    	 cursor_at_eol(void);
+int 		 iswordchar(unsigned char c);
+void		 find_next_word(void);
+void		 delete_next_word(void);
+void		 find_prev_word(void);
+void		 delete_prev_word(void);
+void		 delete_row(size_t at);
+void		 row_append_row(abuf *row, const char *s, int len);
+void		 row_insert_ch(abuf *row, int at, int16_t c);
+void		 row_delete_ch(abuf *row, int at);
+void		 insertch(int16_t c);
+void		 deletech(uint8_t op);
+void		 open_file(const char *filename);
+char		*rows_to_buffer(int *buflen);
+int     	 save_file(void);
+uint16_t	 is_arrow_key(int16_t c);
+int16_t		 get_keypress(void);
+char		*editor_prompt(const char*, void (*cb)(char*, int16_t));
+void		 editor_find_callback(char *query, int16_t c);
+void		 editor_find(void);
+void		 editor_openfile(void);
+int	    	 first_nonwhitespace(abuf *row);
+void		 move_cursor_once(int16_t c, int interactive);
+void		 move_cursor(int16_t c, int interactive);
+void		 uarg_start(void);
+void		 uarg_digit(int d);
+void		 uarg_clear(void);
+int	    	 uarg_get(void);
+void		 newline(void);
+char		*get_cloc_code_lines(const char *filename);
+int	    	 dump_pidfile(void);
+
+
+#endif

editor.c

@@ -0,0 +1,110 @@
+/* editor.c - editor-wide state and functions */
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#include "abuf.h"
+#include "buffer.h"
+#include "core.h"
+#include "editor.h"
+#include "term.h"
+
+/*
+ * Global editor instance
+ */
+struct editor editor = {
+	.cols = 0,
+	.rows     = 0,
+	.mode     = 0,
+	.killring = NULL,
+	.kill     = 0,
+	.no_kill  = 0,
+	.dirtyex  = 0,
+	.uarg     = 0,
+	.ucount   = 0,
+	.msgtm    = 0,
+	.buffers  = NULL,
+	.bufcount = 0,
+	.curbuf   = 0,
+	.bufcap   = 0,
+};
+
+
+void
+editor_set_status(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	vsnprintf(editor.msg, sizeof(editor.msg), fmt, ap);
+	va_end(ap);
+
+	editor.msgtm = time(NULL);
+}
+
+
+void
+init_editor(void)
+{
+	editor.cols = 0;
+	editor.rows = 0;
+
+	if (get_winsz(&editor.rows, &editor.cols) == -1) {
+		die("can't get window size");
+	}
+	editor.rows--; /* status bar */
+	editor.rows--; /* message line */
+
+	/* don't clear out the kill ring:
+	 * killing / yanking across files is helpful, and killring
+	 * is initialized to NULL at program start.
+	 */
+	editor.kill = 0;
+	editor.no_kill = 0;
+
+	editor.msg[0] = '\0';
+	editor.msgtm = 0;
+
+	/* initialize buffer system on first init */
+	if (editor.buffers == NULL && editor.bufcount == 0) {
+		editor.bufcap = 0;
+		buffers_init();
+	}
+}
+
+
+void
+reset_editor(void)
+{
+	buffer *b = buffer_current();
+	if (b == NULL) {
+		return;
+	}
+
+	if (b->row) {
+		for (size_t i = 0; i < b->nrows; i++) {
+			ab_free(&b->row[i]);
+		}
+		free(b->row);
+	}
+
+	b->row = NULL;
+	b->nrows = 0;
+	b->rowoffs = 0;
+	b->coloffs = 0;
+	b->rx = 0;
+	b->curx = 0;
+	b->cury = 0;
+	if (b->filename) {
+		free(b->filename);
+		b->filename = NULL;
+	}
+	b->dirty = 0;
+	b->mark_set = 0;
+	b->mark_curx = 0;
+	b->mark_cury = 0;
+}
+

editor.h

@@ -0,0 +1,35 @@
+#ifndef KE_EDITOR_H
+#define KE_EDITOR_H
+
+#include <termios.h>
+#include <time.h>
+
+
+#include "abuf.h"
+#include "buffer.h"
+
+
+struct editor {
+	size_t		  rows, cols;
+	int		  mode;
+	abuf		 *killring;
+	int		  kill;			/* KILL CHAIN (\m/) */
+	int		  no_kill;		/* don't kill in delete_row */
+	int		  dirtyex;
+	char		  msg[80];
+	int		  uarg, ucount;		/* C-u support */
+	time_t		  msgtm;
+	struct buffer	**buffers;  /* array of buffers */
+	size_t		  bufcount; /* number of buffers */
+	size_t		  curbuf;   /* current buffer index */
+	size_t		  bufcap;   /* current buffer capacity */
+};
+
+
+extern struct editor	 editor;
+void			 editor_set_status(const char *fmt, ...);
+void			 init_editor(void);
+void			 reset_editor(void);
+
+
+#endif /* KE_EDITOR_H */

ke.1

@@ -22,11 +22,21 @@ grandeur. Many commands work with and without control; for example,
 saving a file can be done with either C-k s or C-k C-s. Other commands work
 with ESC or CTRL.
 .Sh K-COMMANDS
+k-command mode can be exited with ESC or C-g.
 .Bl -tag -width xxxxxxxxxxxx -offset indent
 .It C-k BACKSPACE
 Delete from the cursor to the beginning of the line.
 .It C-k SPACE
 Toggle the mark.
+.It C-k -
+If the mark is set, unindent the region.
+.It C-k =
+If the mark is set, indent the region.
+.It C-k b
+Switch to a buffer.
+.It C-k c
+Close the current buffer. If no other buffers are open, an empty
+buffer will be opened. To exit, use C-k q.
 .It C-k d
 Delete from the cursor to the end of the line.
 .It C-k C-d
@@ -34,34 +44,52 @@ Delete the entire line.
 .It C-k e
 Edit a new file. Also C-k C-e.
 .It C-k f
-Incremental find.
+Flush the kill ring.
 .It C-k g
-Go to a specific line. Also C-k C-g.
+Go to a specific line.
+.It C-k j
+Jump to the mark.
 .It C-k l
 List the number of lines of code in a saved file.
 .It C-k m
 Run make(1).
+.It C-k p
+Switch to the next buffer.
 .It C-k q
-exit the editor. Also C-k C-q.
+Exit the editor. If the file has unsaved changes,
+a warning will be printed; a second C-k q will exit.
+.It C-k C-q
+Immediately exit the editor.
+.It C-k C-r
+Reload the current buffer from disk.
 .It C-k s
-save the file, prompting for a filename if needed. Also C-k C-s.
+Save the file, prompting for a filename if needed. Also C-k C-s.
+.It C-k u
+Undo changes (not implemented; marking this k-command as taken).
+.It C-k U
+Redo changes (not implemented; marking this k-command as taken).
 .It C-k x
 save the file and exit. Also C-k C-x.
 .It C-k y
-Yank the killring.
+Yank the kill ring.
 .It C-k \[char92]
 Dump core.
 .El
 .Sh OTHER KEYBINDINGS
 .Bl -tag -width xxxxxxxxxxxx -offset indent
+.It C-g
+In general, C-g cancels an operation.
 .It C-l
 Refresh the display.
 .It C-s
 Incremental find.
+.It C-u
+Universal argument. C-u followed by numbers will repeat an
+operation n times.
 .It C-w
 Kill the region if the mark is set.
 .It C-y
-Yank the killring.
+Yank the kill ring.
 .It ESC BACKSPACE
 Delete the previous word.
 .It ESC b
@@ -71,7 +99,7 @@ Delete the next word.
 .It ESC f
 Move to the next word.
 .It ESC w
-Save the region (if the mark is set) to the killring.
+Save the region (if the mark is set) to the kill ring.
 .It
 .El
 .Sh FIND

killring.c

@@ -0,0 +1,356 @@
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "abuf.h"
+#include "core.h"
+#include "editing.h"
+#include "editor.h"
+#include "killring.h"
+
+
+void
+killring_flush(void)
+{
+	if (editor.killring != NULL) {
+		ab_free(editor.killring);
+		free(editor.killring);
+		editor.killring = NULL;
+	}
+}
+
+
+void
+killring_yank(void)
+{
+	if (editor.killring == NULL) {
+		return;
+	}
+	/*
+	 * Insert killring contents at the cursor without clearing the ring.
+	 * Interpret '\n' as an actual newline() rather than inserting a raw 0x0A
+	 * byte, so yanked content preserves lines correctly.
+	 */
+	for (int i = 0; i < (int)editor.killring->size; i++) {
+		unsigned char ch = (unsigned char)editor.killring->b[i];
+		if (ch == '\n') {
+			newline();
+		} else {
+			insertch(ch);
+		}
+	}
+}
+
+
+void
+killring_start_with_char(unsigned char ch)
+{
+	abuf *row = NULL;
+
+	if (editor.killring != NULL) {
+		ab_free(editor.killring);
+		free(editor.killring);
+		editor.killring = NULL;
+	}
+
+	editor.killring = malloc(sizeof(abuf));
+	assert(editor.killring != NULL);
+	assert(erow_init(editor.killring, 0) == 0);
+
+	/* append one char to empty killring without affecting editor.dirty */
+	row = editor.killring;
+
+	row->b = realloc(row->b, row->size + 2);
+	assert(row->b != NULL);
+	row->b[row->size] = ch;
+	row->size++;
+	row->b[row->size] = '\0';
+}
+
+
+void
+killring_append_char(unsigned char ch)
+{
+	abuf	*row = NULL;
+
+	if (editor.killring == NULL) {
+		killring_start_with_char(ch);
+		return;
+	}
+
+	row = editor.killring;
+	row->b = realloc(row->b, row->size + 2);
+	assert(row->b != NULL);
+	row->b[row->size] = ch;
+	row->size++;
+	row->b[row->size] = '\0';
+}
+
+
+void
+killring_prepend_char(unsigned char ch)
+{
+	abuf	*row = NULL;
+
+	if (editor.killring == NULL) {
+		killring_start_with_char(ch);
+		return;
+	}
+
+	row = editor.killring;
+	row->b = realloc(row->b, row->size + 2);
+	assert(row->b != NULL);
+	memmove(&row->b[1], &row->b[0], row->size + 1);
+	row->b[0] = ch;
+	row->size++;
+}
+
+
+void
+toggle_markset(void)
+{
+	if (EMARK_SET) {
+		EMARK_SET = 0;
+		editor_set_status("Mark cleared.");
+		return;
+	}
+
+	EMARK_SET  = 1;
+	EMARK_CURX = ECURX;
+	EMARK_CURY = ECURY;
+	editor_set_status("Mark set.");
+}
+
+
+int
+cursor_after_mark(void)
+{
+	if (EMARK_CURY < ECURY) {
+		return 1;
+	}
+
+	if (EMARK_CURY > ECURY) {
+		return 0;
+	}
+
+	return ECURX >= EMARK_CURX;
+}
+
+
+int
+count_chars_from_cursor_to_mark(void)
+{
+	size_t	 count = 0;
+	size_t	 curx  = ECURX;
+	size_t	 cury  = ECURY;
+	size_t	 markx = EMARK_CURX;
+	size_t	 marky = EMARK_CURY;
+
+	if (!cursor_after_mark()) {
+		swap_size_t(&curx, &markx);
+		swap_size_t(&curx, &marky);
+	}
+
+	ECURX = markx;
+	ECURY = marky;
+
+	while (ECURY != cury) {
+		while (!cursor_at_eol()) {
+			move_cursor(ARROW_RIGHT, 1);
+			count++;
+		}
+
+		move_cursor(ARROW_RIGHT, 1);
+		count++;
+	}
+
+	while (ECURX != curx) {
+		count++;
+		move_cursor(ARROW_RIGHT, 1);
+	}
+
+	return count;
+}
+
+
+void
+kill_region(void)
+{
+	size_t	 curx  = ECURX;
+	size_t	 cury  = ECURY;
+	size_t	 markx = EMARK_CURX;
+	size_t	 marky = EMARK_CURY;
+
+	if (!EMARK_SET) {
+		return;
+	}
+
+	/* kill the current killring first */
+	killring_flush();
+
+	if (!cursor_after_mark()) {
+		swap_size_t(&curx, &markx);
+		swap_size_t(&cury, &marky);
+	}
+
+	ECURX = markx;
+	ECURY = marky;
+
+	while (ECURY != cury) {
+		while (!cursor_at_eol()) {
+			killring_append_char(EROW[ECURY].b[ECURX]);
+			move_cursor(ARROW_RIGHT, 0);
+		}
+		killring_append_char('\n');
+		move_cursor(ARROW_RIGHT, 0);
+	}
+
+	while (ECURX != curx) {
+		killring_append_char(EROW[ECURY].b[ECURX]);
+		move_cursor(ARROW_RIGHT, 0);
+	}
+
+	editor_set_status("Region killed.");
+	/* clearing the mark needs to be done outside this function;	*
+	 * when deleting the region, the mark needs to be set too.	*/
+}
+
+
+void
+indent_region(void)
+{
+	size_t	 start_row = 0;
+	size_t	 end_row   = 0;
+	size_t	 i         = 0;
+
+	if (!EMARK_SET) {
+		return;
+	}
+
+	if (EMARK_CURY < ECURY) {
+		start_row = EMARK_CURY;
+		end_row   = ECURY;
+	} else if (EMARK_CURY > ECURY) {
+		start_row = ECURY;
+		end_row   = EMARK_CURY;
+	} else {
+		start_row = end_row = ECURY;
+	}
+
+	/* Ensure bounds are valid */
+	if (end_row >= ENROWS) {
+		end_row = ENROWS - 1;
+	}
+
+	if (start_row >= ENROWS) {
+		return;
+	}
+
+	for (i = start_row; i <= end_row; i++) {
+		row_insert_ch(&EROW[i], 0, '\t');
+	}
+
+	ECURX = 0;
+	EDIRTY++;
+}
+
+
+void
+unindent_region(void)
+{
+	size_t	 start_row = 0;
+	size_t	 end_row   = 0;
+	size_t	 i         = 0;
+	size_t	 del       = 0;
+	abuf	*row       = NULL;
+
+	if (!EMARK_SET) {
+		editor_set_status("Mark not set.");
+		return;
+	}
+
+	if (EMARK_CURY < ECURY ||
+	    (EMARK_CURY == ECURY && EMARK_CURX < ECURX)) {
+		start_row = EMARK_CURY;
+		end_row   = ECURY;
+	} else {
+		start_row = ECURY;
+		end_row   = EMARK_CURY;
+	}
+
+	if (start_row >= ENROWS) {
+		return;
+	}
+
+	if (end_row >= ENROWS) {
+		end_row = ENROWS - 1;
+	}
+
+	for (i = start_row; i <= end_row; i++) {
+		row = &EROW[i];
+
+		if (row->size == 0) {
+			continue;
+		}
+
+		if (row->b[0] == '\t') {
+			row_delete_ch(row, 0);
+		} else if (row->b[0] == ' ') {
+			del = 0;
+
+			while (del < TAB_STOP && del < row->size &&
+			       row->b[del] == ' ') {
+				del++;
+			}
+
+			if (del > 0) {
+				/* +1 for NUL */
+				memmove(row->b, row->b + del,
+					row->size - del + 1);
+				row->size -= del;
+			}
+		}
+	}
+
+	ECURX = 0;
+	ECURY = start_row;
+
+	EDIRTY++;
+	editor_set_status("Region unindented");
+}
+
+
+void
+delete_region(void)
+{
+	size_t	 count  = count_chars_from_cursor_to_mark();
+	size_t	 killed = 0;
+	size_t	 curx   = ECURX;
+	size_t	 cury   = ECURY;
+	size_t	 markx  = EMARK_CURX;
+	size_t	 marky  = EMARK_CURY;
+
+	if (!EMARK_SET) {
+		return;
+	}
+
+	if (!cursor_after_mark()) {
+		swap_size_t(&curx, &markx);
+		swap_size_t(&cury, &marky);
+	}
+
+	jump_to_position(markx, marky);
+
+	while (killed < count) {
+		move_cursor(ARROW_RIGHT, 0);
+		deletech(KILLRING_NO_OP);
+		killed++;
+	}
+
+	while (ECURX != markx && ECURY != marky) {
+		deletech(KILLRING_NO_OP);
+	}
+
+	editor.kill = 1;
+	editor_set_status("Region killed.");
+}

killring.h

@@ -0,0 +1,26 @@
+#ifndef KE_KILLRING_H
+#define KE_KILLRING_H
+
+
+#define KILLRING_NO_OP		0	/* don't touch the killring */
+#define KILLRING_APPEND		1	/* append deleted chars */
+#define KILLRING_PREPEND	2	/* prepend deleted chars */
+#define KILLING_SET		3	/* set killring to deleted char */
+#define KILLRING_FLUSH		4	/* clear the killring */
+
+
+void		 killring_flush(void);
+void		 killring_yank(void);
+void		 killring_start_with_char(unsigned char ch);
+void		 killring_append_char(unsigned char ch);
+void		 killring_prepend_char(unsigned char ch);
+void		 toggle_markset(void);
+int	    	 cursor_after_mark(void);
+int	    	 count_chars_from_cursor_to_mark(void);
+void		 kill_region(void);
+void		 indent_region(void);
+void		 unindent_region(void);
+void		 delete_region(void);
+
+
+#endif

process.c

@@ -0,0 +1,438 @@
+#include <errno.h>
+#include <ctype.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <_string.h>
+
+#include "editing.h"
+#include "buffer.h"
+#include "core.h"
+#include "editor.h"
+#include "killring.h"
+#include "term.h"
+#include "process.h"
+
+
+void
+process_kcommand(const int16_t c)
+{
+	char	*buf   = NULL;
+	size_t	 len   = 0;
+	int	 jumpx = 0;
+	int	 jumpy = 0;
+	int	 reps  = 0;
+
+	switch (c) {
+		case BACKSPACE:
+			while (ECURX > 0) {
+				process_normal(BACKSPACE);
+			}
+			break;
+		case '=':
+			if (EMARK_SET) {
+				indent_region();
+			} else {
+				editor_set_status("Mark not set.");
+			}
+			break;
+		case '-':
+			if (EMARK_SET) {
+				unindent_region();
+			} else {
+				editor_set_status("Mark not set.");
+			}
+			break;
+		case CTRL_KEY('\\'):
+			/* sometimes it's nice to dump core */
+			disable_termraw();
+			abort();
+		case '@':
+			if (!dump_pidfile()) {
+				break;
+			}
+			/* FALLTHRU */
+		case '!':
+			/* useful for debugging */
+			editor_set_status("PID: %ld", (long) getpid());
+			break;
+		case ' ':
+			toggle_markset();
+			break;
+		case CTRL_KEY(' '):
+			jumpx = EMARK_CURX;
+			jumpy = EMARK_CURY;
+			EMARK_CURX = ECURX;
+			EMARK_CURY = ECURY;
+
+			jump_to_position(jumpx, jumpy);
+			editor_set_status("Jumped to mark");
+			break;
+		case 'c':
+			buffer_close_current();
+			break;
+		case 'd':
+			if (ECURX == 0 && cursor_at_eol()) {
+				delete_row(ECURY);
+				return;
+			}
+
+			reps = uarg_get();
+			while (reps--) {
+				while ((EROW[ECURY].size - ECURX) > 0) {
+					process_normal(DEL_KEY);
+				}
+				if (reps) {
+					newline();
+				}
+			}
+
+			break;
+		case DEL_KEY:
+		case CTRL_KEY('d'):
+			reps = uarg_get();
+
+			while (reps--) {
+				delete_row(ECURY);
+			}
+			break;
+		case 'e':
+		case CTRL_KEY('e'):
+			if (EDIRTY && editor.dirtyex) {
+				editor_set_status(
+					"File not saved - C-k e again to open a new file anyways.");
+				editor.dirtyex = 0;
+				return;
+			}
+			editor_openfile();
+			break;
+		case 'f':
+			if (editor.killring == NULL || editor.killring->size == 0) {
+				editor_set_status("The kill ring is empty.");
+				break;
+			}
+
+			len = editor.killring ? editor.killring->size : 0;
+			killring_flush();
+			editor_set_status("Kill ring cleared (%lu characters)", len);
+			break;
+		case 'n':
+			buffer_next();
+			break;
+		case 'p':
+			buffer_prev();
+			break;
+		case 'b':
+			buffer_switch_by_name();
+			break;
+		case 'g':
+			goto_line();
+			break;
+		case 'j':
+			if (!EMARK_SET) {
+				editor_set_status("Mark not set.");
+				break;
+			}
+
+			jumpx = EMARK_CURX;
+			jumpy = EMARK_CURY;
+			EMARK_CURX = ECURX;
+			EMARK_CURY = ECURY;
+
+			jump_to_position(jumpx, jumpy);
+			editor_set_status("Jumped to mark; mark is now the previous location.");
+			break;
+		case 'l':
+			buf = get_cloc_code_lines(EFILENAME);
+
+			editor_set_status("Lines of code: %s", buf);
+			free(buf);
+			break;
+		case 'm':
+			/* todo: fix the process failed: success issue */
+			if (system("make") != 0) {
+				editor_set_status(
+					"process failed: %s",
+					strerror(errno));
+			} else {
+				editor_set_status("make: ok");
+			}
+			break;
+		case 'q':
+			if (EDIRTY && editor.dirtyex) {
+				editor_set_status(
+					"File not saved - C-k q again to quit.");
+				editor.dirtyex = 0;
+				return;
+			}
+			exit(0);
+		case CTRL_KEY('q'):
+			exit(0);
+		case CTRL_KEY('r'):
+			if (EDIRTY && editor.dirtyex) {
+				editor_set_status("File not saved - C-k C-r again to reload.");
+				editor.dirtyex = 0;
+				return;
+			}
+
+			jumpx = ECURX;
+			jumpy = ECURY;
+			buf = strdup(EFILENAME);
+
+			reset_editor();
+			open_file(buf);
+			display_refresh();
+			free(buf);
+
+			jump_to_position(jumpx, jumpy);
+			editor_set_status("file reloaded");
+			break;
+		case CTRL_KEY('s'):
+		case 's':
+			save_file();
+			break;
+		case CTRL_KEY('x'):
+		case 'x':
+			exit(save_file());
+		case 'u':
+			reps = uarg_get();
+
+			while (reps--) {}
+			editor_set_status("Undo not implemented.");
+			break;
+		case 'U':
+			reps = uarg_get();
+
+			while (reps--) {}
+			editor_set_status("Redo not implemented.");
+			break;
+		case 'y':
+			reps = uarg_get();
+
+			while (reps--) {
+				killring_yank();
+			}
+			break;
+		case ESC_KEY:
+		case CTRL_KEY('g'):
+			break;
+		default:
+			if (isprint(c)) {
+				editor_set_status("unknown kcommand '%c'", c);
+				break;
+			}
+
+			editor_set_status("unknown kcommand: %04x", c);
+			return;
+	}
+
+	editor.dirtyex = 1;
+}
+
+
+void
+process_normal(int16_t c)
+{
+	size_t	 cols = 0;
+	size_t	 rows = 0;
+	int	 reps = 0;
+
+	/* C-u handling – must be the very first thing */
+	if (c == CTRL_KEY('u')) {
+		uarg_start();
+		return;
+	}
+
+	/* digits after a C-u are part of the argument */
+	if (editor.uarg && c >= '0' && c <= '9') {
+		uarg_digit(c - '0');
+		return;
+	}
+
+	if (is_arrow_key(c)) {
+		/* moving the cursor breaks a delete sequence */
+		editor.kill = 0;
+		move_cursor(c, 1);
+		return;
+	}
+
+	switch (c) {
+	case '\r':
+		newline();
+		break;
+	case CTRL_KEY('k'):
+		editor.mode = MODE_KCOMMAND;
+		return;
+	case BACKSPACE:
+	case CTRL_KEY('h'):
+	case CTRL_KEY('d'):
+	case DEL_KEY:
+		if (c == DEL_KEY || c == CTRL_KEY('d')) {
+			reps = uarg_get();
+			while (reps-- > 0) {
+				move_cursor(ARROW_RIGHT, 1);
+				deletech(KILLRING_APPEND);
+			}
+		} else {
+			reps = uarg_get();
+			while (reps-- > 0) {
+				deletech(KILLRING_PREPEND);
+			}
+		}
+		break;
+	case CTRL_KEY('a'):	/* beginning of line */
+	case HOME_KEY:
+		move_cursor(CTRL_KEY('a'), 1);
+		break;
+	case CTRL_KEY('e'):	/* end of line */
+	case END_KEY:
+		move_cursor(CTRL_KEY('e'), 1);
+		break;
+	case CTRL_KEY('g'):
+		break;
+	case CTRL_KEY('l'):
+		if (get_winsz(&rows, &cols) == 0) {
+			editor.rows = rows;
+			editor.cols = cols;
+		} else {
+			editor_set_status("Couldn't update window size.");
+		}
+		display_refresh();
+		break;
+	case CTRL_KEY('s'):
+		editor_find();
+		break;
+	case CTRL_KEY('w'):
+		kill_region();
+		delete_region();
+		toggle_markset();
+		break;
+	case CTRL_KEY('y'):
+		reps = uarg_get();
+
+		while (reps-- > 0) {
+			killring_yank();
+		}
+		break;
+	case ESC_KEY:
+		editor.mode = MODE_ESCAPE;
+		break;
+	default:
+		if (c == TAB_KEY) {
+			reps = uarg_get();
+
+			while (reps-- > 0) {
+				insertch(c);
+			}
+		} else if (c >= 0x20 && c != 0x7f) {
+			reps = uarg_get();
+
+			while (reps-- > 0) {
+				insertch(c);
+			}
+		}
+		break;
+	}
+
+	editor.dirtyex = 1;
+}
+
+
+void
+process_escape(const int16_t c)
+{
+	int	 reps = 0;
+
+	editor_set_status("hi");
+
+	switch (c) {
+		case '>':
+			ECURY = ENROWS;
+			ECURX = 0;
+			break;
+		case '<':
+			ECURY = 0;
+			ECURX = 0;
+			break;
+		case 'b':
+			reps = uarg_get();
+
+			while (reps--) {
+				find_prev_word();
+			}
+			break;
+		case 'd':
+			reps = uarg_get();
+
+			while (reps--) {
+				delete_next_word();
+			}
+			break;
+		case 'f':
+			reps = uarg_get();
+
+			while (reps--) {
+				find_next_word();
+			}
+			break;
+		case 'm':
+			toggle_markset();
+			break;
+		case 'w':
+			if (!EMARK_SET) {
+				editor_set_status("mark isn't set");
+				break;
+			}
+			kill_region();
+			toggle_markset();
+			break;
+		case BACKSPACE:
+			reps = uarg_get();
+
+			while (reps--) {
+				delete_prev_word();
+			}
+			break;
+		case ESC_KEY:
+		case CTRL_KEY('g'):
+			break; /* escape from escape-mode the movie */
+		default:
+			editor_set_status("unknown ESC key: %04x", c);
+	}
+
+	uarg_clear();
+}
+
+
+int
+process_keypress(void)
+{
+	const int16_t	 c = get_keypress();
+
+	if (c <= 0) {
+		return 0;
+	}
+
+	switch (editor.mode) {
+	case MODE_KCOMMAND:
+		process_kcommand(c);
+		editor.mode = MODE_NORMAL;
+		break;
+	case MODE_NORMAL:
+		process_normal(c);
+		break;
+	case MODE_ESCAPE:
+		process_escape(c);
+		editor.mode = MODE_NORMAL;
+		break;
+	default:
+		editor_set_status("we're in the %d-D space now cap'n",
+		                  editor.mode);
+		editor.mode = MODE_NORMAL;
+	}
+
+	return 1;
+}

process.h

@@ -0,0 +1,22 @@
+#ifndef KE_PROCESS_H
+#define KE_PROCESS_H
+
+
+#include <stdint.h>
+/*
+ * define the keyboard input modes
+ * normal: no special mode
+ * kcommand: ^k commands
+ * escape: what happens when you hit escape?
+ */
+#define	MODE_NORMAL		0
+#define	MODE_KCOMMAND		1
+#define	MODE_ESCAPE		2
+
+void		 process_kcommand(int16_t c);
+void		 process_normal(int16_t c);
+void		 process_escape(int16_t c);
+int	    	 process_keypress(void);
+
+
+#endif

scratch.c

@@ -0,0 +1,206 @@
+/*
+ * scratch.c - ideas in progress
+ */
+
+#include "buffer.h"
+#include "abuf.h"
+#include <ctype.h>
+#include <string.h>
+
+#define REFLOW_MARGIN		72
+
+void
+reflow_region(void)
+{
+ int		 start_row, end_row, i, col, wlen, this_len;
+ abuf		*row;
+ struct abuf	 buf = ABUF_INIT;
+ struct abuf	 out = ABUF_INIT;
+	int		 in_paragraph = 0;
+	int		 indent_len = 0;
+	char		 indent[REFLOW_MARGIN + 1];
+	char		 word[REFLOW_MARGIN + 1];
+	char		*e = NULL;
+	char		*p = NULL;
+	char		*s = NULL;
+
+ if (EMARK_SET) {
+        if (EMARK_CURY < ECURY ||
+            (EMARK_CURY == ECURY &&
+                EMARK_CURX < ECURX)) {
+            start_row = EMARK_CURY;
+            end_row = ECURY;
+        } else {
+            start_row = ECURY;
+            end_row = EMARK_CURY;
+        }
+    } else {
+        start_row = end_row = ECURY;
+        while (start_row > 0 && EROW[start_row - 1].size > 0) {
+            start_row--;
+        }
+
+        while (end_row < ENROWS - 1 &&
+            EROW[end_row + 1].size > 0) {
+            end_row++;
+        }
+    }
+
+ if (start_row >= ENROWS) {
+        return;
+    }
+
+ if (end_row >= ENROWS) {
+        end_row = ENROWS - 1;
+    }
+
+ for (i = start_row; i <= end_row; i++) {
+        row = &EROW[i];
+
+		if (row->size == 0) {
+			if (in_paragraph) {
+				ab_append(&buf, "\n", 1);
+				in_paragraph = 0;
+			}
+
+			ab_append(&buf, "\n", 1);
+			continue;
+		}
+
+        if (!in_paragraph) {
+            indent_len = 0;
+            while (indent_len < (int)row->size &&
+                (row->b[indent_len] == ' ' ||
+                    row->b[indent_len] == '\t')) {
+                indent[indent_len] = row->b[indent_len], indent_len++;
+            }
+
+            indent[indent_len] = '\0';
+            in_paragraph = 1;
+        }
+
+        ab_append(&buf, row->b + indent_len, row->size - indent_len);
+        ab_append(&buf, " ", 1);
+    }
+
+	if (in_paragraph) {
+		ab_append(&buf, "\n", 1);
+	}
+
+
+	p = buf.b;
+	col = 0;
+
+	while (p != NULL && *p != '\0') {
+		while (*p && isspace((unsigned char)*p) &&
+			*p != '\n') {
+			p++;
+		}
+
+		if (*p == '\0') {
+			break;
+		}
+
+		wlen = 0;
+		while (*p && !isspace((unsigned char)*p)) {
+			if (wlen < REFLOW_MARGIN)
+				word[wlen++] = *p;
+			p++;
+		}
+		word[wlen] = '\0';
+
+		if (*p == '\n' && (p[1] == '\n' || p[1] == '\0')) {
+			ab_append(&out, "\n", 1); /* flush */
+			col = 0;
+			p++; /* consume the extra \n */
+			continue;
+		}
+
+		this_len = wlen;
+		if (col > 0) {
+			this_len++; /* space before word */
+		}
+
+		if (col == 0) {
+			ab_append(&out, indent, indent_len);
+			col = indent_len;
+		}
+
+		if (col + this_len > REFLOW_MARGIN && col > 0) {
+			ab_append(&out, "\n", 1);
+			ab_append(&out, indent, indent_len);
+			col = indent_len;
+		}
+
+		if (col > 0) {
+			ab_append(&out, " ", 1);
+			col++;
+		}
+
+		ab_append(&out, word, wlen);
+		col += wlen;
+	}
+
+	if (col > 0) {
+		ab_append(&out, "\n", 1);
+	}
+
+	/* the old switcharoo */
+	buf = out;
+	ab_free(&out);
+
+
+ for (i = end_row; i >= start_row; i--) {
+        delete_row(i);
+    }
+
+ s = buf.b;
+ while ((e = strchr(s, '\n'))) {
+     erow_insert(start_row++, s, e - s);
+     s = e + 1;
+ }
+
+	ab_free(&buf);
+
+    EDIRTY++;
+    editor_set_status("Region reflowed to %d columns", REFLOW_MARGIN);
+}
+
+
+static inline
+void clamp_curx_to_row(void)
+{
+	abuf	*row  = NULL;
+	int	 maxx = 0;
+
+	if (ECURY >= ENROWS) {
+		return;
+	}
+
+	row = &EROW[ECURY];
+	if (ECURX < 0) {
+		ECURX = 0;
+	}
+
+	maxx = (int) row->size;
+	if (ECURX > maxx) {
+		ECURX = maxx;
+	}
+}
+
+static inline
+void set_cursor(int col, int row)
+{
+	if (row < 0) {
+		row = 0;
+	}
+
+	if (row > ENROWS) {
+		row = ENROWS;
+	}
+	
+	ECURY = row;
+	ECURX = col;
+	
+	clamp_curx_to_row();
+}

term.c

@@ -0,0 +1,312 @@
+#include <sys/ioctl.h>
+#include <assert.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <termios.h>
+#include <unistd.h>
+
+#include "abuf.h"
+#include "core.h"
+#include "buffer.h"
+#include "editing.h"
+#include "editor.h"
+#include "process.h"
+#include "term.h"
+
+#define ESCSEQ "\x1b["
+
+
+static struct termios saved_entry_term;
+
+
+void
+enable_termraw(void)
+{
+	struct termios raw;
+
+	if (tcgetattr(STDIN_FILENO, &raw) == -1) {
+		die("tcgetattr while enabling raw mode");
+	}
+
+	cfmakeraw(&raw);
+	raw.c_cc[VMIN]  = 0;
+	raw.c_cc[VTIME] = 1;
+
+	if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw) == -1) {
+		die("tcsetattr while enabling raw mode");
+	}
+}
+
+
+void
+display_clear(abuf *ab)
+{
+	if (ab == NULL) {
+		kwrite(STDOUT_FILENO, ESCSEQ "2J", 4);
+		kwrite(STDOUT_FILENO, ESCSEQ "H", 3);
+	} else {
+		ab_append(ab, ESCSEQ "2J", 4);
+		ab_append(ab, ESCSEQ "H", 3);
+	}
+}
+
+
+void
+disable_termraw(void)
+{
+	display_clear(NULL);
+
+	if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &saved_entry_term) == -1) {
+		die("couldn't disable terminal raw mode");
+	}
+}
+
+
+void
+setup_terminal(void)
+{
+	if (tcgetattr(STDIN_FILENO, &saved_entry_term) == -1) {
+		die("can't snapshot terminal settings");
+	}
+
+	enable_termraw();
+}
+
+
+int
+get_winsz(size_t *rows, size_t *cols)
+{
+    struct winsize ws;
+
+    if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == -1 || ws.ws_col == 0) {
+        return -1;
+    }
+
+    *cols = (size_t)ws.ws_col;
+    *rows = (size_t)ws.ws_row;
+
+    return 0;
+}
+
+
+void
+draw_rows(abuf *ab)
+{
+	abuf	*row              = NULL;
+	char	 buf[editor.cols];
+	char	 c                = 0;
+	size_t	 j                = 0;
+	size_t	 filerow          = 0;
+	size_t	 y                = 0;
+	size_t	 len              = 0;
+	size_t	 padding          = 0;
+	size_t	 printed          = 0;
+	size_t	 rx               = 0;
+
+	for (y = 0; y < editor.rows; y++) {
+		filerow = y + EROWOFFS;
+		if (filerow >= ENROWS) {
+			if ((ENROWS == 0) && (y == editor.rows / 3)) {
+				len = snprintf(buf,
+				               sizeof(buf),
+				               "%s",
+				               KE_VERSION);
+				padding = (editor.rows - len) / 2;
+
+				if (padding) {
+					ab_append(ab, "|", 1);
+					padding--;
+				}
+
+				while (padding--)
+					ab_append(ab, " ", 1);
+				ab_append(ab, buf, len);
+			} else {
+				ab_append(ab, "|", 1);
+			}
+		} else {
+			row = &EROW[filerow];
+			j = 0;
+			rx = printed = 0;
+
+			while (j < row->size && printed < editor.cols) {
+				c = row->b[j];
+
+				if (rx < ECOLOFFS) {
+					if (c == '\t') rx += (TAB_STOP - (rx % TAB_STOP));
+					else if (c < 0x20) rx += 3;
+					else rx++;
+					j++;
+					continue;
+				}
+
+				if (c == '\t') {
+					int sp = TAB_STOP - (rx % TAB_STOP);
+					for (int k = 0; k < sp && printed < editor.cols; k++) {
+						ab_appendch(ab, ' ');
+						printed++;
+						rx++;
+					}
+				} else if (c < 0x20) {
+					char seq[4];
+					snprintf(seq, sizeof(seq), "\\%02x", c);
+					ab_append(ab, seq, 3);
+					printed += 3;
+					rx += 3;
+				} else {
+					ab_appendch(ab, c);
+					printed++;
+					rx++;
+				}
+				j++;
+			}
+			len = printed;
+		}
+		ab_append(ab, ESCSEQ "K", 3);
+		ab_append(ab, "\r\n", 2);
+	}
+}
+
+
+char
+status_mode_char(void)
+{
+	switch (editor.mode) {
+	case MODE_NORMAL:
+		return 'N';
+	case MODE_KCOMMAND:
+		return 'K';
+	case MODE_ESCAPE:
+		return 'E';
+	default:
+		return '?';
+	}
+}
+
+
+void
+draw_status_bar(abuf *ab)
+{
+	char	 status[editor.cols];
+	char	 rstatus[editor.cols];
+	char	 mstatus[editor.cols];
+	size_t	 len                   = 0;
+	size_t	 rlen                  = 0;
+
+	len = snprintf(status,
+		       sizeof(status),
+		       "%c%cke: %.20s - %lu lines",
+		       status_mode_char(),
+		       EDIRTY ? '!' : '-',
+		       EFILENAME ? EFILENAME : "[no file]",
+                ENROWS);
+
+	if (EMARK_SET) {
+		snprintf(mstatus,
+		         sizeof(mstatus),
+		         " | M: %lu, %lu ",
+		         EMARK_CURX + 1,
+		         EMARK_CURY + 1);
+	} else {
+		snprintf(mstatus, sizeof(mstatus), " | M:clear ");
+	}
+
+	rlen = snprintf(rstatus,
+	                sizeof(rstatus),
+	                "L%lu/%lu C%lu %s",
+	                ECURY + 1,
+	                ENROWS,
+	                ECURX + 1,
+	                mstatus);
+
+	ab_append(ab, ESCSEQ "7m", 4);
+	ab_append(ab, status, len);
+	while (len < editor.cols) {
+		if (editor.cols - len == rlen) {
+			ab_append(ab, rstatus, rlen);
+			break;
+		}
+		ab_append(ab, " ", 1);
+		len++;
+	}
+
+	ab_append(ab, ESCSEQ "m", 3);
+	ab_append(ab, "\r\n", 2);
+}
+
+
+void
+draw_message_line(abuf *ab)
+{
+	size_t	 len = strlen(editor.msg);
+
+	ab_append(ab, ESCSEQ "K", 3);
+	if (len > editor.cols) {
+		len = editor.cols;
+	}
+
+	if (len && time(NULL) - editor.msgtm < MSG_TIMEO) {
+		ab_append(ab, editor.msg, len);
+	}
+}
+
+
+void
+scroll(void)
+{
+	const abuf	*row = NULL;
+
+	ERX = 0;
+	if (ECURY < ENROWS) {
+		row = &EROW[ECURY];
+		ERX = erow_render_to_cursor(row, ECURX);
+	}
+
+	if (ECURY < EROWOFFS) {
+		EROWOFFS = ECURY;
+	}
+
+	if (ECURY >= EROWOFFS + editor.rows) {
+		EROWOFFS = ECURY - editor.rows + 1;
+	}
+
+	if (ERX < ECOLOFFS) {
+		ECOLOFFS = ERX;
+	}
+
+	if (ERX >= ECOLOFFS + editor.cols) {
+		ECOLOFFS = ERX - editor.cols + 1;
+	}
+}
+
+
+void
+display_refresh(void)
+{
+	char	 buf[32] = {0};
+	abuf	 ab      = ABUF_INIT;
+
+	scroll();
+
+	ab_append(&ab, ESCSEQ "?25l", 6);
+	ab_append(&ab, ESCSEQ "H", 3);
+	display_clear(&ab);
+
+	draw_rows(&ab);
+	draw_status_bar(&ab);
+	draw_message_line(&ab);
+
+	snprintf(buf,
+	         sizeof(buf),
+	         ESCSEQ "%lu;%luH",
+	         (ECURY - EROWOFFS) + 1,
+	         (ERX - ECOLOFFS) + 1);
+	ab_append(&ab, buf, kstrnlen(buf, 32));
+	/* ab_append(&ab, ESCSEQ "1;2H", 7); */
+	ab_append(&ab, ESCSEQ "?25h", 6);
+
+	kwrite(STDOUT_FILENO, ab.b, (int)ab.size);
+	ab_free(&ab);
+}

term.h

@@ -0,0 +1,30 @@
+#ifndef KE_TERM_H
+#define KE_TERM_H
+
+#include "abuf.h"
+
+
+/* Terminal control/setup API */
+void		 enable_termraw(void);
+void		 disable_termraw(void);
+void		 setup_terminal(void);
+void		 display_clear(abuf *ab);
+void		 draw_rows(abuf *ab);
+char		 status_mode_char(void);
+void		 draw_status_bar(abuf *ab);
+void		 draw_message_line(abuf *ab);
+void		 scroll(void);
+void		 display_refresh(void);
+
+/*
+ * get_winsz uses the TIOCGWINSZ to get the window size.
+ *
+ * there's a fallback way to do this, too, that involves moving the
+ * cursor down and to the left \x1b[999C\x1b[999B. I'm going to skip
+ * on this for now because it's bloaty and this works on OpenBSD and
+ * Linux, at least.
+ */
+int  get_winsz(size_t *rows, size_t *cols);
+
+
+#endif /* KE_TERM_H */

undo.c

@@ -0,0 +1,240 @@
+/*
+ * undo.c: ke's undo system
+ */
+
+#include <assert.h>
+#include <stdlib.h>
+
+#include "abuf.h"
+#include "buffer.h"
+#include "undo.h"
+
+
+undo_node *
+undo_node_new(undo_kind kind)
+{
+	undo_node	*node = NULL;
+
+	node = (undo_node *)malloc(sizeof(undo_node));
+	assert(node != NULL);
+
+	node->kind = kind;
+	node->row = node->col = 0;
+
+	ab_init(&node->text);
+	
+	node->next = NULL;
+	node->next = NULL;
+
+	return node;
+}
+
+
+void
+undo_node_free(undo_node *node)
+{
+	if (node == NULL) {
+		return;
+	}
+
+	ab_free(&node->text);
+}
+
+
+void
+undo_node_free_all(undo_node *node)
+{
+	undo_node	*next = NULL;
+
+	if (node == NULL) {
+		return;
+	}
+
+	while (node != NULL) {
+		next = node->next;
+		undo_node_free(node);
+		free(node);
+		node = next;
+	}
+}
+
+
+void
+undo_tree_init(undo_tree *tree)
+{
+	assert(tree != NULL);
+
+	tree->root    = NULL;
+	tree->current = NULL;
+	tree->pending = NULL;
+}
+
+
+void
+undo_tree_free(undo_tree *tree)
+{
+	assert(tree != NULL);
+
+	undo_node_free(tree->pending);
+	undo_node_free_all(tree->root);
+	undo_tree_init(tree);
+}
+
+
+void
+undo_begin(undo_tree *tree, undo_kind kind)
+{
+	undo_node	*pending = NULL;
+	
+	if (tree->pending != NULL) {
+		if (tree->pending->kind == kind) {
+			/* don't initiate a new undo sequence if it's the same kind */
+			return;
+		}
+		undo_commit(tree);
+	}
+
+	pending = undo_node_new(kind);
+	assert(pending != NULL);
+
+	tree->pending = pending;
+}
+
+
+void
+undo_prepend(undo_tree *tree, abuf *buf)
+{
+	assert(tree != NULL);
+	assert(tree->pending != NULL);
+
+	ab_prepend_ab(&tree->pending->text, buf);
+}
+
+
+void
+undo_append(undo_tree *tree, abuf *buf)
+{
+	assert(tree != NULL);
+	assert(tree->pending != NULL);
+
+	ab_append_ab(&tree->pending->text, buf);
+}
+
+
+void
+undo_prependch(undo_tree *tree, char c)
+{
+	assert(tree != NULL);
+	assert(tree->pending != NULL);
+
+	ab_prependch(&tree->pending->text, c);
+}
+
+
+void
+undo_appendch(undo_tree *tree, char c)
+{
+	assert(tree != NULL);
+	assert(tree->pending != NULL);
+
+	ab_appendch(&tree->pending->text, c);
+}
+
+
+void
+undo_commit(undo_tree *tree)
+{
+	assert(tree != NULL);
+
+	if (tree->pending == NULL) {
+		return;
+	}
+
+	if (tree->root == NULL) {
+		assert(tree->current == NULL);
+
+		tree->root    = tree->pending;
+		tree->current = tree->pending;
+		tree->pending = NULL;
+
+		return;
+	}
+
+	assert(tree->current != NULL);
+	if (tree->current->next != NULL) {
+		undo_node_free_all(tree->current->next);
+	}
+
+	tree->pending->prev = tree->current;
+	tree->current->next = tree->pending;
+	tree->current       = tree->pending;
+	tree->pending       = NULL;
+}
+
+
+static int
+undo_apply_undo(struct buffer *buf)
+{
+	undo_node	*node = buf->undo.current;
+
+	switch (node->kind) {
+	case UNDO_INSERT:
+		break;
+	default:
+		return 0;
+	}
+
+	return 0;
+}
+
+
+int
+undo_apply(struct buffer *buf, int direction)
+{
+	(void)direction;
+
+	if (buf == NULL) {
+		return 0;
+	}
+
+	undo_commit(&buf->undo);
+	if (buf->undo.current == NULL) {
+		return 0;
+	}
+
+	if (direction == UNDO_DIR_UNDO) {
+		return undo_apply_undo(buf);
+	} else if (direction == UNDO_DIR_UNDO) {
+		return 0;
+	} else {
+		return 0;
+	}
+
+	return 0;
+}
+
+
+int
+editor_undo(struct buffer *buf)
+{
+	if (buf == NULL) {
+		return 0;
+	}
+
+	undo_commit(&buf->undo);
+	return undo_apply(buf, UNDO_DIR_UNDO);
+	
+}
+
+
+int
+editor_redo(struct buffer *buf)
+{
+	if (buf == NULL) {
+		return 0;
+	}
+
+	undo_commit(&buf->undo);
+	return undo_apply(buf, UNDO_DIR_REDO);
+}
+

undo.h

@@ -0,0 +1,56 @@
+#include <stddef.h>
+
+#include "abuf.h"
+
+
+#ifndef KE_UNDO_H
+#define KE_UNDO_H
+
+
+struct	 buffer;
+
+
+#define		UNDO_DIR_UNDO		-1
+#define		UNDO_DIR_REDO		 1
+
+
+typedef enum undo_kind {
+	UNDO_INSERT  = 1 << 0,
+	UNDO_UNKNOWN = 1 << 1,
+} undo_kind;
+
+
+typedef struct undo_node {
+	undo_kind		 kind;
+	size_t			 row, col;
+	abuf			 text;
+
+	struct undo_node	*next;
+	struct undo_node	*prev;
+
+} undo_node;
+
+
+typedef struct undo_tree {
+	undo_node	*root;		/* the start of the undo sequence */
+	undo_node	*current;	/* where we are currently at */
+	undo_node	*pending;	/* the current undo operations being built */
+} undo_tree;
+
+
+undo_node	*undo_node_new(undo_kind kind);
+void		 undo_node_free(undo_node *node);
+void		 undo_tree_init(undo_tree *tree);
+void		 undo_tree_free(undo_tree *tree);
+void		 undo_begin(undo_tree *tree, undo_kind kind);
+void		 undo_prepend(undo_tree *tree, abuf *buf);
+void		 undo_append(undo_tree *tree, abuf *buf);
+void		 undo_prependch(undo_tree *tree, char c);
+void		 undo_appendch(undo_tree *tree, char c);
+void		 undo_commit(undo_tree *tree);
+int		 undo_apply(struct buffer *buf, int direction);
+int		 editor_undo(struct buffer *buf);
+int		 editor_redo(struct buffer *buf);
+
+
+#endif