factored out all cursor movement and deletion commands into the new compilation unit move-commands.c

* This made sense to include both `W` and `V`, so we also included `D` and `K`.
  `^Q` is included since it converts between lines and glyphs.
* These are all single-letter commands, so they aren't complete parser states
  but callbacks to be referenced in teco_machine_main_transition_t.

4 files changed, 676 insertions, 599 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 055cde7..e7a8545 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -44,6 +44,7 @@ libsciteco_base_la_SOURCES = main.c sciteco.h list.h \
                              ring.c ring.h \
                              parser.c parser.h \
                              core-commands.c core-commands.h \
+                             move-commands.c move-commands.h \
                              search.c search.h \
                              spawn.c spawn.h \
                              glob.c glob.h \
diff --git a/src/core-commands.c b/src/core-commands.c
index 8cbb4be..f39f6f9 100644
--- a/src/core-commands.c
+++ b/src/core-commands.c
@@ -44,6 +44,7 @@
 #include "qreg.h"
 #include "qreg-commands.h"
 #include "goto-commands.h"
+#include "move-commands.h"
 #include "core-commands.h"
 
 static teco_state_t *teco_state_control_input(teco_machine_main_t *ctx, gunichar chr, GError **error);
@@ -516,422 +517,6 @@ teco_state_start_cmdline_pop(teco_machine_main_t *ctx, GError **error)
 	g_set_error_literal(error, TECO_ERROR, TECO_ERROR_CMDLINE, "");
 }
 
-/*$ J jump
- * [position]J -- Go to position in buffer
- * [position]:J -> Success|Failure
- *
- * Sets dot to <position>.
- * If <position> is omitted, 0 is implied and \(lqJ\(rq will
- * go to the beginning of the buffer.
- *
- * If <position> is outside the range of the buffer, the
- * command yields an error.
- * If colon-modified, the command will instead return a
- * condition boolean signalling whether the position could
- * be changed or not.
- */
-static void
-teco_state_start_jump(teco_machine_main_t *ctx, GError **error)
-{
-	teco_int_t v;
-
-	if (!teco_expressions_pop_num_calc(&v, 0, error))
-		return;
-
-	gssize pos = teco_interface_glyphs2bytes(v);
-	if (pos >= 0) {
-		if (teco_current_doc_must_undo())
-			undo__teco_interface_ssm(SCI_GOTOPOS,
-			                         teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0), 0);
-		teco_interface_ssm(SCI_GOTOPOS, pos, 0);
-
-		if (teco_machine_main_eval_colon(ctx) > 0)
-			teco_expressions_push(TECO_SUCCESS);
-	} else if (teco_machine_main_eval_colon(ctx) > 0) {
-		teco_expressions_push(TECO_FAILURE);
-	} else {
-		teco_error_move_set(error, "J");
-		return;
-	}
-}
-
-static teco_bool_t
-teco_move_chars(teco_int_t n)
-{
-	sptr_t pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
-	gssize next_pos = teco_interface_glyphs2bytes_relative(pos, n);
-	if (next_pos < 0)
-		return TECO_FAILURE;
-
-	teco_interface_ssm(SCI_GOTOPOS, next_pos, 0);
-	if (teco_current_doc_must_undo())
-		undo__teco_interface_ssm(SCI_GOTOPOS, pos, 0);
-
-	return TECO_SUCCESS;
-}
-
-/*$ C move
- * [n]C -- Move dot <n> characters
- * -C
- * [n]:C -> Success|Failure
- *
- * Adds <n> to dot. 1 or -1 is implied if <n> is omitted.
- * Fails if <n> would move dot off-page.
- * The colon modifier results in a success-boolean being
- * returned instead.
- */
-static void
-teco_state_start_move(teco_machine_main_t *ctx, GError **error)
-{
-	teco_int_t v;
-
-	if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
-		return;
-
-	teco_bool_t rc = teco_move_chars(v);
-	if (teco_machine_main_eval_colon(ctx) > 0) {
-		teco_expressions_push(rc);
-	} else if (teco_is_failure(rc)) {
-		teco_error_move_set(error, "C");
-		return;
-	}
-}
-
-/*$ R reverse
- * [n]R -- Move dot <n> characters backwards
- * -R
- * [n]:R -> Success|Failure
- *
- * Subtracts <n> from dot.
- * It is equivalent to \(lq-nC\(rq.
- */
-static void
-teco_state_start_reverse(teco_machine_main_t *ctx, GError **error)
-{
-	teco_int_t v;
-
-	if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
-		return;
-
-	teco_bool_t rc = teco_move_chars(-v);
-	if (teco_machine_main_eval_colon(ctx) > 0) {
-		teco_expressions_push(rc);
-	} else if (teco_is_failure(rc)) {
-		teco_error_move_set(error, "R");
-		return;
-	}
-}
-
-static teco_bool_t
-teco_move_lines(teco_int_t n)
-{
-	sptr_t pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
-	sptr_t line = teco_interface_ssm(SCI_LINEFROMPOSITION, pos, 0) + n;
-
-	if (!teco_validate_line(line))
-		return TECO_FAILURE;
-
-	teco_interface_ssm(SCI_GOTOLINE, line, 0);
-	if (teco_current_doc_must_undo())
-		undo__teco_interface_ssm(SCI_GOTOPOS, pos, 0);
-
-	return TECO_SUCCESS;
-}
-
-/*$ L line
- * [n]L -- Move dot <n> lines forwards
- * -L
- * [n]:L -> Success|Failure
- *
- * Move dot to the beginning of the line specified
- * relatively to the current line.
- * Therefore a value of 0 for <n> goes to the
- * beginning of the current line, 1 will go to the
- * next line, -1 to the previous line etc.
- * If <n> is omitted, 1 or -1 is implied depending on
- * the sign prefix.
- *
- * If <n> would move dot off-page, the command yields
- * an error.
- * The colon-modifer results in a condition boolean
- * being returned instead.
- */
-static void
-teco_state_start_line(teco_machine_main_t *ctx, GError **error)
-{
-	teco_int_t v;
-
-	if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
-		return;
-
-	teco_bool_t rc = teco_move_lines(v);
-	if (teco_machine_main_eval_colon(ctx) > 0) {
-		teco_expressions_push(rc);
-	} else if (teco_is_failure(rc)) {
-		teco_error_move_set(error, "L");
-		return;
-	}
-}
-
-/*$ B backwards
- * [n]B -- Move dot <n> lines backwards
- * -B
- * [n]:B -> Success|Failure
- *
- * Move dot to the beginning of the line <n>
- * lines before the current one.
- * It is equivalent to \(lq-nL\(rq.
- */
-static void
-teco_state_start_back(teco_machine_main_t *ctx, GError **error)
-{
-	teco_int_t v;
-
-	if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
-		return;
-
-	teco_bool_t rc = teco_move_lines(-v);
-	if (teco_machine_main_eval_colon(ctx) > 0) {
-		teco_expressions_push(rc);
-	} else if (teco_is_failure(rc)) {
-		teco_error_move_set(error, "B");
-		return;
-	}
-}
-
-/*
- * NOTE: This implementation has a constant/maximum number of Scintilla
- * messages, compared to using SCI_WORDENDPOSITION.
- * This pays out only beginning at n > 3, though.
- * But most importantly SCI_WORDENDPOSITION(p, FALSE) does not actually skip
- * over all non-word characters.
- */
-static gboolean
-teco_find_words(gsize *pos, teco_int_t n)
-{
-	if (!n)
-		return TRUE;
-
-	g_auto(teco_string_t) wchars;
-	wchars.len = teco_interface_ssm(SCI_GETWORDCHARS, 0, 0);
-	wchars.data = g_malloc(wchars.len + 1);
-	teco_interface_ssm(SCI_GETWORDCHARS, 0, (sptr_t)wchars.data);
-	wchars.data[wchars.len] = '\0';
-
-	sptr_t gap = teco_interface_ssm(SCI_GETGAPPOSITION, 0, 0);
-
-	if (n > 0) {
-		/* scan forward */
-		gsize len = teco_interface_ssm(SCI_GETLENGTH, 0, 0);
-		gsize range_len = gap > *pos ? gap - *pos : len - *pos;
-		if (!range_len)
-			return FALSE;
-		const gchar *buffer, *p;
-		p = buffer = (const gchar *)teco_interface_ssm(SCI_GETRANGEPOINTER, *pos, range_len);
-
-		while (n--) {
-			gboolean skip_word = TRUE;
-
-			for (;;) {
-				if (*pos == len)
-					/* end of document */
-					return n == 0;
-				if (p-buffer >= range_len) {
-					g_assert(*pos == gap);
-					range_len = len - gap;
-					p = buffer = (const gchar *)teco_interface_ssm(SCI_GETRANGEPOINTER, gap, range_len);
-				}
-				/*
-				 * FIXME: Is this safe or do we have to look up Unicode code points?
-				 */
-				if ((!teco_string_contains(&wchars, *p)) == skip_word) {
-					if (!skip_word)
-						break;
-					skip_word = !skip_word;
-					continue;
-				}
-				(*pos)++;
-				p++;
-			}
-		}
-
-		return TRUE;
-	}
-
-	/* scan backwards */
-	gsize range_len = gap < *pos ? *pos - gap : *pos;
-	if (!range_len)
-		return FALSE;
-	const gchar *buffer, *p;
-	buffer = (const gchar *)teco_interface_ssm(SCI_GETRANGEPOINTER, *pos - range_len, range_len);
-	p = buffer+range_len;
-
-	while (n++) {
-		gboolean skip_word = FALSE;
-
-		for (;;) {
-			if (*pos == 0)
-				/* beginning of document */
-				return n == 0;
-			if (p == buffer) {
-				g_assert(*pos == gap);
-				range_len = *pos;
-				buffer = (const gchar *)teco_interface_ssm(SCI_GETRANGEPOINTER, 0, range_len);
-				p = buffer+range_len;
-			}
-			/*
-			 * FIXME: Is this safe or do we have to look up Unicode code points?
-			 */
-			if ((!teco_string_contains(&wchars, p[-1])) == skip_word) {
-				if (skip_word)
-					break;
-				skip_word = !skip_word;
-				continue;
-			}
-			(*pos)--;
-			p--;
-		}
-	}
-
-	return TRUE;
-}
-
-/*$ W word
- * [n]W -- Move dot by words
- * -W
- * [n]:W -> Success|Failure
- *
- * Move dot <n> words forward.
- *   - If <n> is positive, dot is positioned at the beginning
- *     of the word <n> words after the current one.
- *   - If <n> is negative, dot is positioned at the beginning
- *     of the word, <-n> words before the current one.
- *   - If <n> is zero, dot is not moved.
- *
- * \(lqW\(rq uses Scintilla's definition of a word as
- * configurable using the
- * .B SCI_SETWORDCHARS
- * message.
- *
- * If the requested word would lie beyond the range of the
- * buffer, the command yields an error.
- * If colon-modified it instead returns a condition code.
- */
-static void
-teco_state_start_word(teco_machine_main_t *ctx, GError **error)
-{
-	teco_int_t v;
-	if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
-		return;
-	sptr_t pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
-
-	gsize word_pos = pos;
-	if (!teco_find_words(&word_pos, v)) {
-		if (!teco_machine_main_eval_colon(ctx))
-			teco_error_move_set(error, "W");
-		else
-			teco_expressions_push(TECO_FAILURE);
-		return;
-	}
-
-	if (teco_current_doc_must_undo())
-		undo__teco_interface_ssm(SCI_GOTOPOS, pos, 0);
-	teco_interface_ssm(SCI_GOTOPOS, word_pos, 0);
-	if (teco_machine_main_eval_colon(ctx) > 0)
-		teco_expressions_push(TECO_SUCCESS);
-}
-
-static gboolean
-teco_delete_words(teco_int_t n)
-{
-	if (!n)
-		return TRUE;
-
-	sptr_t pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
-
-	gsize start_pos = pos, end_pos = pos;
-	if (!teco_find_words(n > 0 ? &end_pos : &start_pos, n))
-		return FALSE;
-	g_assert(start_pos <= end_pos);
-
-	teco_interface_ssm(SCI_BEGINUNDOACTION, 0, 0);
-	teco_interface_ssm(SCI_DELETERANGE, start_pos, end_pos-start_pos);
-	teco_interface_ssm(SCI_ENDUNDOACTION, 0, 0);
-
-	if (teco_current_doc_must_undo()) {
-		undo__teco_interface_ssm(SCI_GOTOPOS, pos, 0);
-		undo__teco_interface_ssm(SCI_UNDO, 0, 0);
-	}
-	teco_ring_dirtify();
-
-	return TRUE;
-}
-
-/*$ V
- * [n]V -- Delete words forward
- * -V
- * [n]:V -> Success|Failure
- *
- * Deletes the next <n> words until the beginning of the
- * n'th word after the current one.
- * If <n> is negative, deletes up to the beginning of the
- * word, <-n> words before the current one.
- * \(lq-V\(rq in the middle of a word deletes until the beginning
- * of the word.
- * If <n> is omitted, 1 or -1 is implied depending on the
- * sign prefix.
- *
- * It uses Scintilla's definition of a word as configurable
- * using the
- * .B SCI_SETWORDCHARS
- * message.
- *
- * If the words to delete extend beyond the range of the
- * buffer, the command yields an error.
- * If colon-modified it instead returns a condition code.
- */
-static void
-teco_state_start_delete_words(teco_machine_main_t *ctx, GError **error)
-{
-	teco_int_t v;
-
-	if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
-		return;
-
-	gboolean rc = teco_delete_words(v);
-	if (teco_machine_main_eval_colon(ctx) > 0) {
-		teco_expressions_push(teco_bool(rc));
-	} else if (!rc) {
-		teco_error_words_set(error, "V");
-		return;
-	}
-}
-
-/*$ Y
- * [n]Y -- Delete word backwards
- * -Y
- * [n]:Y -> Success|Failure
- *
- * Delete <n> words backward.
- * <n>Y is equivalent to \(lq-nV\(rq.
- */
-static void
-teco_state_start_delete_words_back(teco_machine_main_t *ctx, GError **error)
-{
-	teco_int_t v;
-
-	if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
-		return;
-
-	gboolean rc = teco_delete_words(-v);
-	if (teco_machine_main_eval_colon(ctx) > 0) {
-		teco_expressions_push(teco_bool(rc));
-	} else if (!rc) {
-		teco_error_words_set(error, "Y");
-		return;
-	}
-}
-
 /*$ "=" print
  * <n>= -- Show value as message
  *
@@ -960,128 +545,6 @@ teco_state_start_print(teco_machine_main_t *ctx, GError **error)
 	teco_interface_msg(TECO_MSG_USER, "%" TECO_INT_FORMAT, v);
 }
 
-static gboolean
-teco_state_start_kill(teco_machine_main_t *ctx, const gchar *cmd, gboolean by_lines, GError **error)
-{
-	teco_bool_t rc;
-	gssize from, len; /* in bytes */
-
-	if (!teco_expressions_eval(FALSE, error))
-		return FALSE;
-
-	if (teco_expressions_args() <= 1) {
-		from = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
-		if (by_lines) {
-			teco_int_t line;
-			if (!teco_expressions_pop_num_calc(&line, teco_num_sign, error))
-				return FALSE;
-			line += teco_interface_ssm(SCI_LINEFROMPOSITION, from, 0);
-			len = teco_interface_ssm(SCI_POSITIONFROMLINE, line, 0) - from;
-			rc = teco_bool(teco_validate_line(line));
-		} else {
-			teco_int_t len_glyphs;
-			if (!teco_expressions_pop_num_calc(&len_glyphs, teco_num_sign, error))
-				return FALSE;
-			gssize to = teco_interface_glyphs2bytes_relative(from, len_glyphs);
-			rc = teco_bool(to >= 0);
-			len = to-from;
-		}
-		if (len < 0) {
-			len *= -1;
-			from -= len;
-		}
-	} else {
-		teco_int_t to_glyphs = teco_expressions_pop_num(0);
-		gssize to = teco_interface_glyphs2bytes(to_glyphs);
-		teco_int_t from_glyphs = teco_expressions_pop_num(0);
-		from = teco_interface_glyphs2bytes(from_glyphs);
-		len = to - from;
-		rc = teco_bool(len >= 0 && from >= 0 && to >= 0);
-	}
-
-	if (teco_machine_main_eval_colon(ctx) > 0) {
-		teco_expressions_push(rc);
-	} else if (teco_is_failure(rc)) {
-		teco_error_range_set(error, cmd);
-		return FALSE;
-	}
-
-	if (len == 0 || teco_is_failure(rc))
-		return TRUE;
-
-	if (teco_current_doc_must_undo()) {
-		sptr_t pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
-		undo__teco_interface_ssm(SCI_GOTOPOS, pos, 0);
-		undo__teco_interface_ssm(SCI_UNDO, 0, 0);
-	}
-
-	/*
-	 * Should always generate an undo action.
-	 */
-	teco_interface_ssm(SCI_BEGINUNDOACTION, 0, 0);
-	teco_interface_ssm(SCI_DELETERANGE, from, len);
-	teco_interface_ssm(SCI_ENDUNDOACTION, 0, 0);
-	teco_ring_dirtify();
-
-	return TRUE;
-}
-
-/*$ K kill
- * [n]K -- Kill lines
- * -K
- * from,to K
- * [n]:K -> Success|Failure
- * from,to:K -> Success|Failure
- *
- * Deletes characters up to the beginning of the
- * line <n> lines after or before the current one.
- * If <n> is 0, \(lqK\(rq will delete up to the beginning
- * of the current line.
- * If <n> is omitted, the sign prefix will be implied.
- * So to delete the entire line regardless of the position
- * in it, one can use \(lq0KK\(rq.
- *
- * If the deletion is beyond the buffer's range, the command
- * will yield an error unless it has been colon-modified
- * so it returns a condition code.
- *
- * If two arguments <from> and <to> are available, the
- * command is synonymous to <from>,<to>D.
- */
-static void
-teco_state_start_kill_lines(teco_machine_main_t *ctx, GError **error)
-{
-	teco_state_start_kill(ctx, "K", TRUE, error);
-}
-
-/*$ D delete
- * [n]D -- Delete characters
- * -D
- * from,to D
- * [n]:D -> Success|Failure
- * from,to:D -> Success|Failure
- *
- * If <n> is positive, the next <n> characters (up to and
- * character .+<n>) are deleted.
- * If <n> is negative, the previous <n> characters are
- * deleted.
- * If <n> is omitted, the sign prefix will be implied.
- *
- * If two arguments can be popped from the stack, the
- * command will delete the characters with absolute
- * position <from> up to <to> from the current buffer.
- *
- * If the character range to delete is beyond the buffer's
- * range, the command will yield an error unless it has
- * been colon-modified so it returns a condition code
- * instead.
- */
-static void
-teco_state_start_delete_chars(teco_machine_main_t *ctx, GError **error)
-{
-	teco_state_start_kill(ctx, "D", FALSE, error);
-}
-
 /*$ A
  * [n]A -> code -- Get character code from buffer
  * -A -> code
@@ -1854,67 +1317,6 @@ teco_state_control_radix(teco_machine_main_t *ctx, GError **error)
 	}
 }
 
-/*$ ^Q lines2glyphs glyphs2lines
- * [n]^Q -> glyphs -- Convert between lines and glyph lengths or positions
- * [position]:^Q -> line
- *
- * Converts between line and glyph arguments.
- * It returns the number of glyphs between dot and the <n>-th next
- * line (or previous line if <n> is negative).
- * Consequently \(lq^QC\(rq is equivalent to \(lqL\(rq, but less efficient.
- *
- * If colon-modified, an absolute buffer position is converted to the line that
- * contains this position, beginning with 1.
- * Without arguments, \(lq:^Q\(rq returns the current line.
- */
-/*
- * FIXME: Perhaps there should be a way to convert an absolute line to an
- * absolute position.
- */
-static void
-teco_state_control_lines2glyphs(teco_machine_main_t *ctx, GError **error)
-{
-	if (!teco_expressions_eval(FALSE, error))
-		return;
-
-	if (teco_machine_main_eval_colon(ctx)) {
-		gssize pos;
-
-		if (!teco_expressions_args()) {
-			pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
-		} else {
-			teco_int_t v;
-
-			if (!teco_expressions_pop_num_calc(&v, 0, error))
-				return;
-
-			pos = teco_interface_glyphs2bytes(v);
-			if (pos < 0) {
-				teco_error_range_set(error, "^Q");
-				return;
-			}
-		}
-
-		teco_expressions_push(teco_interface_ssm(SCI_LINEFROMPOSITION, pos, 0)+1);
-	} else {
-		teco_int_t v;
-
-		if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
-			return;
-
-		sptr_t pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
-		sptr_t line = teco_interface_ssm(SCI_LINEFROMPOSITION, pos, 0) + v;
-
-		if (!teco_validate_line(line)) {
-			teco_error_range_set(error, "^Q");
-			return;
-		}
-
-		sptr_t line_pos = teco_interface_ssm(SCI_POSITIONFROMLINE, line, 0);
-		teco_expressions_push(teco_interface_bytes2glyphs(line_pos) - teco_interface_bytes2glyphs(pos));
-	}
-}
-
 /*$ ^E glyphs2bytes bytes2glyphs
  * glyphs^E -> bytes -- Translate between glyph and byte indexes
  * bytes:^E -> glyphs
diff --git a/src/move-commands.c b/src/move-commands.c
new file mode 100644
index 0000000..8abd8ca
--- /dev/null
+++ b/src/move-commands.c
@@ -0,0 +1,635 @@
+/*
+ * Copyright (C) 2012-2025 Robin Haberkorn
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+/**
+ * @file Movement \b and corresponding deletion commands.
+ * This also includes the lines to glyphs conversion command.
+ */
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <glib.h>
+#include <glib/gstdio.h>
+
+#include "sciteco.h"
+#include "string-utils.h"
+#include "expressions.h"
+#include "interface.h"
+#include "parser.h"
+#include "ring.h"
+#include "undo.h"
+#include "error.h"
+#include "move-commands.h"
+
+/*$ J jump
+ * [position]J -- Go to position in buffer
+ * [position]:J -> Success|Failure
+ *
+ * Sets dot to <position>.
+ * If <position> is omitted, 0 is implied and \(lqJ\(rq will
+ * go to the beginning of the buffer.
+ *
+ * If <position> is outside the range of the buffer, the
+ * command yields an error.
+ * If colon-modified, the command will instead return a
+ * condition boolean signalling whether the position could
+ * be changed or not.
+ */
+void
+teco_state_start_jump(teco_machine_main_t *ctx, GError **error)
+{
+	teco_int_t v;
+
+	if (!teco_expressions_pop_num_calc(&v, 0, error))
+		return;
+
+	gssize pos = teco_interface_glyphs2bytes(v);
+	if (pos >= 0) {
+		if (teco_current_doc_must_undo())
+			undo__teco_interface_ssm(SCI_GOTOPOS,
+			                         teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0), 0);
+		teco_interface_ssm(SCI_GOTOPOS, pos, 0);
+
+		if (teco_machine_main_eval_colon(ctx) > 0)
+			teco_expressions_push(TECO_SUCCESS);
+	} else if (teco_machine_main_eval_colon(ctx) > 0) {
+		teco_expressions_push(TECO_FAILURE);
+	} else {
+		teco_error_move_set(error, "J");
+		return;
+	}
+}
+
+static teco_bool_t
+teco_move_chars(teco_int_t n)
+{
+	sptr_t pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
+	gssize next_pos = teco_interface_glyphs2bytes_relative(pos, n);
+	if (next_pos < 0)
+		return TECO_FAILURE;
+
+	teco_interface_ssm(SCI_GOTOPOS, next_pos, 0);
+	if (teco_current_doc_must_undo())
+		undo__teco_interface_ssm(SCI_GOTOPOS, pos, 0);
+
+	return TECO_SUCCESS;
+}
+
+/*$ C move
+ * [n]C -- Move dot <n> characters
+ * -C
+ * [n]:C -> Success|Failure
+ *
+ * Adds <n> to dot. 1 or -1 is implied if <n> is omitted.
+ * Fails if <n> would move dot off-page.
+ * The colon modifier results in a success-boolean being
+ * returned instead.
+ */
+void
+teco_state_start_move(teco_machine_main_t *ctx, GError **error)
+{
+	teco_int_t v;
+
+	if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
+		return;
+
+	teco_bool_t rc = teco_move_chars(v);
+	if (teco_machine_main_eval_colon(ctx) > 0) {
+		teco_expressions_push(rc);
+	} else if (teco_is_failure(rc)) {
+		teco_error_move_set(error, "C");
+		return;
+	}
+}
+
+/*$ R reverse
+ * [n]R -- Move dot <n> characters backwards
+ * -R
+ * [n]:R -> Success|Failure
+ *
+ * Subtracts <n> from dot.
+ * It is equivalent to \(lq-nC\(rq.
+ */
+void
+teco_state_start_reverse(teco_machine_main_t *ctx, GError **error)
+{
+	teco_int_t v;
+
+	if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
+		return;
+
+	teco_bool_t rc = teco_move_chars(-v);
+	if (teco_machine_main_eval_colon(ctx) > 0) {
+		teco_expressions_push(rc);
+	} else if (teco_is_failure(rc)) {
+		teco_error_move_set(error, "R");
+		return;
+	}
+}
+
+static teco_bool_t
+teco_move_lines(teco_int_t n)
+{
+	sptr_t pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
+	sptr_t line = teco_interface_ssm(SCI_LINEFROMPOSITION, pos, 0) + n;
+
+	if (!teco_validate_line(line))
+		return TECO_FAILURE;
+
+	teco_interface_ssm(SCI_GOTOLINE, line, 0);
+	if (teco_current_doc_must_undo())
+		undo__teco_interface_ssm(SCI_GOTOPOS, pos, 0);
+
+	return TECO_SUCCESS;
+}
+
+/*$ L line
+ * [n]L -- Move dot <n> lines forwards
+ * -L
+ * [n]:L -> Success|Failure
+ *
+ * Move dot to the beginning of the line specified
+ * relatively to the current line.
+ * Therefore a value of 0 for <n> goes to the
+ * beginning of the current line, 1 will go to the
+ * next line, -1 to the previous line etc.
+ * If <n> is omitted, 1 or -1 is implied depending on
+ * the sign prefix.
+ *
+ * If <n> would move dot off-page, the command yields
+ * an error.
+ * The colon-modifer results in a condition boolean
+ * being returned instead.
+ */
+void
+teco_state_start_line(teco_machine_main_t *ctx, GError **error)
+{
+	teco_int_t v;
+
+	if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
+		return;
+
+	teco_bool_t rc = teco_move_lines(v);
+	if (teco_machine_main_eval_colon(ctx) > 0) {
+		teco_expressions_push(rc);
+	} else if (teco_is_failure(rc)) {
+		teco_error_move_set(error, "L");
+		return;
+	}
+}
+
+/*$ B backwards
+ * [n]B -- Move dot <n> lines backwards
+ * -B
+ * [n]:B -> Success|Failure
+ *
+ * Move dot to the beginning of the line <n>
+ * lines before the current one.
+ * It is equivalent to \(lq-nL\(rq.
+ */
+void
+teco_state_start_back(teco_machine_main_t *ctx, GError **error)
+{
+	teco_int_t v;
+
+	if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
+		return;
+
+	teco_bool_t rc = teco_move_lines(-v);
+	if (teco_machine_main_eval_colon(ctx) > 0) {
+		teco_expressions_push(rc);
+	} else if (teco_is_failure(rc)) {
+		teco_error_move_set(error, "B");
+		return;
+	}
+}
+
+/*
+ * NOTE: This implementation has a constant/maximum number of Scintilla
+ * messages, compared to using SCI_WORDENDPOSITION.
+ * This pays out only beginning at n > 3, though.
+ * But most importantly SCI_WORDENDPOSITION(p, FALSE) does not actually skip
+ * over all non-word characters.
+ */
+static gboolean
+teco_find_words(gsize *pos, teco_int_t n)
+{
+	if (!n)
+		return TRUE;
+
+	g_auto(teco_string_t) wchars;
+	wchars.len = teco_interface_ssm(SCI_GETWORDCHARS, 0, 0);
+	wchars.data = g_malloc(wchars.len + 1);
+	teco_interface_ssm(SCI_GETWORDCHARS, 0, (sptr_t)wchars.data);
+	wchars.data[wchars.len] = '\0';
+
+	sptr_t gap = teco_interface_ssm(SCI_GETGAPPOSITION, 0, 0);
+
+	if (n > 0) {
+		/* scan forward */
+		gsize len = teco_interface_ssm(SCI_GETLENGTH, 0, 0);
+		gsize range_len = gap > *pos ? gap - *pos : len - *pos;
+		if (!range_len)
+			return FALSE;
+		const gchar *buffer, *p;
+		p = buffer = (const gchar *)teco_interface_ssm(SCI_GETRANGEPOINTER, *pos, range_len);
+
+		while (n--) {
+			gboolean skip_word = TRUE;
+
+			for (;;) {
+				if (*pos == len)
+					/* end of document */
+					return n == 0;
+				if (p-buffer >= range_len) {
+					g_assert(*pos == gap);
+					range_len = len - gap;
+					p = buffer = (const gchar *)teco_interface_ssm(SCI_GETRANGEPOINTER, gap, range_len);
+				}
+				/*
+				 * FIXME: Is this safe or do we have to look up Unicode code points?
+				 */
+				if ((!teco_string_contains(&wchars, *p)) == skip_word) {
+					if (!skip_word)
+						break;
+					skip_word = !skip_word;
+					continue;
+				}
+				(*pos)++;
+				p++;
+			}
+		}
+
+		return TRUE;
+	}
+
+	/* scan backwards */
+	gsize range_len = gap < *pos ? *pos - gap : *pos;
+	if (!range_len)
+		return FALSE;
+	const gchar *buffer, *p;
+	buffer = (const gchar *)teco_interface_ssm(SCI_GETRANGEPOINTER, *pos - range_len, range_len);
+	p = buffer+range_len;
+
+	while (n++) {
+		gboolean skip_word = FALSE;
+
+		for (;;) {
+			if (*pos == 0)
+				/* beginning of document */
+				return n == 0;
+			if (p == buffer) {
+				g_assert(*pos == gap);
+				range_len = *pos;
+				buffer = (const gchar *)teco_interface_ssm(SCI_GETRANGEPOINTER, 0, range_len);
+				p = buffer+range_len;
+			}
+			/*
+			 * FIXME: Is this safe or do we have to look up Unicode code points?
+			 */
+			if ((!teco_string_contains(&wchars, p[-1])) == skip_word) {
+				if (skip_word)
+					break;
+				skip_word = !skip_word;
+				continue;
+			}
+			(*pos)--;
+			p--;
+		}
+	}
+
+	return TRUE;
+}
+
+/*$ W word
+ * [n]W -- Move dot by words
+ * -W
+ * [n]:W -> Success|Failure
+ *
+ * Move dot <n> words forward.
+ *   - If <n> is positive, dot is positioned at the beginning
+ *     of the word <n> words after the current one.
+ *   - If <n> is negative, dot is positioned at the beginning
+ *     of the word, <-n> words before the current one.
+ *   - If <n> is zero, dot is not moved.
+ *
+ * \(lqW\(rq uses Scintilla's definition of a word as
+ * configurable using the
+ * .B SCI_SETWORDCHARS
+ * message.
+ *
+ * If the requested word would lie beyond the range of the
+ * buffer, the command yields an error.
+ * If colon-modified it instead returns a condition code.
+ */
+void
+teco_state_start_word(teco_machine_main_t *ctx, GError **error)
+{
+	teco_int_t v;
+	if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
+		return;
+	sptr_t pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
+
+	gsize word_pos = pos;
+	if (!teco_find_words(&word_pos, v)) {
+		if (!teco_machine_main_eval_colon(ctx))
+			teco_error_move_set(error, "W");
+		else
+			teco_expressions_push(TECO_FAILURE);
+		return;
+	}
+
+	if (teco_current_doc_must_undo())
+		undo__teco_interface_ssm(SCI_GOTOPOS, pos, 0);
+	teco_interface_ssm(SCI_GOTOPOS, word_pos, 0);
+	if (teco_machine_main_eval_colon(ctx) > 0)
+		teco_expressions_push(TECO_SUCCESS);
+}
+
+static gboolean
+teco_delete_words(teco_int_t n)
+{
+	if (!n)
+		return TRUE;
+
+	sptr_t pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
+
+	gsize start_pos = pos, end_pos = pos;
+	if (!teco_find_words(n > 0 ? &end_pos : &start_pos, n))
+		return FALSE;
+	g_assert(start_pos <= end_pos);
+
+	teco_interface_ssm(SCI_BEGINUNDOACTION, 0, 0);
+	teco_interface_ssm(SCI_DELETERANGE, start_pos, end_pos-start_pos);
+	teco_interface_ssm(SCI_ENDUNDOACTION, 0, 0);
+
+	if (teco_current_doc_must_undo()) {
+		undo__teco_interface_ssm(SCI_GOTOPOS, pos, 0);
+		undo__teco_interface_ssm(SCI_UNDO, 0, 0);
+	}
+	teco_ring_dirtify();
+
+	return TRUE;
+}
+
+/*$ V
+ * [n]V -- Delete words forward
+ * -V
+ * [n]:V -> Success|Failure
+ *
+ * Deletes the next <n> words until the beginning of the
+ * n'th word after the current one.
+ * If <n> is negative, deletes up to the beginning of the
+ * word, <-n> words before the current one.
+ * \(lq-V\(rq in the middle of a word deletes until the beginning
+ * of the word.
+ * If <n> is omitted, 1 or -1 is implied depending on the
+ * sign prefix.
+ *
+ * It uses Scintilla's definition of a word as configurable
+ * using the
+ * .B SCI_SETWORDCHARS
+ * message.
+ *
+ * If the words to delete extend beyond the range of the
+ * buffer, the command yields an error.
+ * If colon-modified it instead returns a condition code.
+ */
+void
+teco_state_start_delete_words(teco_machine_main_t *ctx, GError **error)
+{
+	teco_int_t v;
+
+	if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
+		return;
+
+	gboolean rc = teco_delete_words(v);
+	if (teco_machine_main_eval_colon(ctx) > 0) {
+		teco_expressions_push(teco_bool(rc));
+	} else if (!rc) {
+		teco_error_words_set(error, "V");
+		return;
+	}
+}
+
+/*$ Y
+ * [n]Y -- Delete word backwards
+ * -Y
+ * [n]:Y -> Success|Failure
+ *
+ * Delete <n> words backward.
+ * <n>Y is equivalent to \(lq-nV\(rq.
+ */
+void
+teco_state_start_delete_words_back(teco_machine_main_t *ctx, GError **error)
+{
+	teco_int_t v;
+
+	if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
+		return;
+
+	gboolean rc = teco_delete_words(-v);
+	if (teco_machine_main_eval_colon(ctx) > 0) {
+		teco_expressions_push(teco_bool(rc));
+	} else if (!rc) {
+		teco_error_words_set(error, "Y");
+		return;
+	}
+}
+
+static gboolean
+teco_state_start_kill(teco_machine_main_t *ctx, const gchar *cmd, gboolean by_lines, GError **error)
+{
+	teco_bool_t rc;
+	gssize from, len; /* in bytes */
+
+	if (!teco_expressions_eval(FALSE, error))
+		return FALSE;
+
+	if (teco_expressions_args() <= 1) {
+		from = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
+		if (by_lines) {
+			teco_int_t line;
+			if (!teco_expressions_pop_num_calc(&line, teco_num_sign, error))
+				return FALSE;
+			line += teco_interface_ssm(SCI_LINEFROMPOSITION, from, 0);
+			len = teco_interface_ssm(SCI_POSITIONFROMLINE, line, 0) - from;
+			rc = teco_bool(teco_validate_line(line));
+		} else {
+			teco_int_t len_glyphs;
+			if (!teco_expressions_pop_num_calc(&len_glyphs, teco_num_sign, error))
+				return FALSE;
+			gssize to = teco_interface_glyphs2bytes_relative(from, len_glyphs);
+			rc = teco_bool(to >= 0);
+			len = to-from;
+		}
+		if (len < 0) {
+			len *= -1;
+			from -= len;
+		}
+	} else {
+		teco_int_t to_glyphs = teco_expressions_pop_num(0);
+		gssize to = teco_interface_glyphs2bytes(to_glyphs);
+		teco_int_t from_glyphs = teco_expressions_pop_num(0);
+		from = teco_interface_glyphs2bytes(from_glyphs);
+		len = to - from;
+		rc = teco_bool(len >= 0 && from >= 0 && to >= 0);
+	}
+
+	if (teco_machine_main_eval_colon(ctx) > 0) {
+		teco_expressions_push(rc);
+	} else if (teco_is_failure(rc)) {
+		teco_error_range_set(error, cmd);
+		return FALSE;
+	}
+
+	if (len == 0 || teco_is_failure(rc))
+		return TRUE;
+
+	if (teco_current_doc_must_undo()) {
+		sptr_t pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
+		undo__teco_interface_ssm(SCI_GOTOPOS, pos, 0);
+		undo__teco_interface_ssm(SCI_UNDO, 0, 0);
+	}
+
+	/*
+	 * Should always generate an undo action.
+	 */
+	teco_interface_ssm(SCI_BEGINUNDOACTION, 0, 0);
+	teco_interface_ssm(SCI_DELETERANGE, from, len);
+	teco_interface_ssm(SCI_ENDUNDOACTION, 0, 0);
+	teco_ring_dirtify();
+
+	return TRUE;
+}
+
+/*$ K kill
+ * [n]K -- Kill lines
+ * -K
+ * from,to K
+ * [n]:K -> Success|Failure
+ * from,to:K -> Success|Failure
+ *
+ * Deletes characters up to the beginning of the
+ * line <n> lines after or before the current one.
+ * If <n> is 0, \(lqK\(rq will delete up to the beginning
+ * of the current line.
+ * If <n> is omitted, the sign prefix will be implied.
+ * So to delete the entire line regardless of the position
+ * in it, one can use \(lq0KK\(rq.
+ *
+ * If the deletion is beyond the buffer's range, the command
+ * will yield an error unless it has been colon-modified
+ * so it returns a condition code.
+ *
+ * If two arguments <from> and <to> are available, the
+ * command is synonymous to <from>,<to>D.
+ */
+void
+teco_state_start_kill_lines(teco_machine_main_t *ctx, GError **error)
+{
+	teco_state_start_kill(ctx, "K", TRUE, error);
+}
+
+/*$ D delete
+ * [n]D -- Delete characters
+ * -D
+ * from,to D
+ * [n]:D -> Success|Failure
+ * from,to:D -> Success|Failure
+ *
+ * If <n> is positive, the next <n> characters (up to and
+ * character .+<n>) are deleted.
+ * If <n> is negative, the previous <n> characters are
+ * deleted.
+ * If <n> is omitted, the sign prefix will be implied.
+ *
+ * If two arguments can be popped from the stack, the
+ * command will delete the characters with absolute
+ * position <from> up to <to> from the current buffer.
+ *
+ * If the character range to delete is beyond the buffer's
+ * range, the command will yield an error unless it has
+ * been colon-modified so it returns a condition code
+ * instead.
+ */
+void
+teco_state_start_delete_chars(teco_machine_main_t *ctx, GError **error)
+{
+	teco_state_start_kill(ctx, "D", FALSE, error);
+}
+
+/*$ ^Q lines2glyphs glyphs2lines
+ * [n]^Q -> glyphs -- Convert between lines and glyph lengths or positions
+ * [position]:^Q -> line
+ *
+ * Converts between line and glyph arguments.
+ * It returns the number of glyphs between dot and the <n>-th next
+ * line (or previous line if <n> is negative).
+ * Consequently \(lq^QC\(rq is equivalent to \(lqL\(rq, but less efficient.
+ *
+ * If colon-modified, an absolute buffer position is converted to the line that
+ * contains this position, beginning with 1.
+ * Without arguments, \(lq:^Q\(rq returns the current line.
+ */
+/*
+ * FIXME: Perhaps there should be a way to convert an absolute line to an
+ * absolute position.
+ */
+void
+teco_state_control_lines2glyphs(teco_machine_main_t *ctx, GError **error)
+{
+	if (!teco_expressions_eval(FALSE, error))
+		return;
+
+	if (teco_machine_main_eval_colon(ctx)) {
+		gssize pos;
+
+		if (!teco_expressions_args()) {
+			pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
+		} else {
+			teco_int_t v;
+
+			if (!teco_expressions_pop_num_calc(&v, 0, error))
+				return;
+
+			pos = teco_interface_glyphs2bytes(v);
+			if (pos < 0) {
+				teco_error_range_set(error, "^Q");
+				return;
+			}
+		}
+
+		teco_expressions_push(teco_interface_ssm(SCI_LINEFROMPOSITION, pos, 0)+1);
+	} else {
+		teco_int_t v;
+
+		if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
+			return;
+
+		sptr_t pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
+		sptr_t line = teco_interface_ssm(SCI_LINEFROMPOSITION, pos, 0) + v;
+
+		if (!teco_validate_line(line)) {
+			teco_error_range_set(error, "^Q");
+			return;
+		}
+
+		sptr_t line_pos = teco_interface_ssm(SCI_POSITIONFROMLINE, line, 0);
+		teco_expressions_push(teco_interface_bytes2glyphs(line_pos) - teco_interface_bytes2glyphs(pos));
+	}
+}
diff --git a/src/move-commands.h b/src/move-commands.h
new file mode 100644
index 0000000..36acec8
--- /dev/null
+++ b/src/move-commands.h
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2012-2025 Robin Haberkorn
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+#include <glib.h>
+
+#include "parser.h"
+
+void teco_state_start_jump(teco_machine_main_t *ctx, GError **error);
+
+void teco_state_start_move(teco_machine_main_t *ctx, GError **error);
+void teco_state_start_reverse(teco_machine_main_t *ctx, GError **error);
+
+void teco_state_start_line(teco_machine_main_t *ctx, GError **error);
+void teco_state_start_back(teco_machine_main_t *ctx, GError **error);
+
+void teco_state_start_word(teco_machine_main_t *ctx, GError **error);
+
+void teco_state_start_delete_words(teco_machine_main_t *ctx, GError **error);
+void teco_state_start_delete_words_back(teco_machine_main_t *ctx, GError **error);
+
+void teco_state_start_kill_lines(teco_machine_main_t *ctx, GError **error);
+void teco_state_start_delete_chars(teco_machine_main_t *ctx, GError **error);
+
+void teco_state_control_lines2glyphs(teco_machine_main_t *ctx, GError **error);