support the ::S anchored search (string comparison) command (and ::FD, ::FR, ::FS as well)

* The colon modifier can now occur 2 times.
  Specifying `@` more than once or `:` more than twice is an error now.
* Commands do not check for excess colon modifiers - almost every command would have
  to check it. Instead, a double colon will simply behave like a single colon on most
  commands.
* All search commands inherit the anchored semantics, but it's not very useful in some combinations
  like -::S, ::N or ::FK.
  That's why the `::` variants are not documented everywhere.
* The lexer.checkheader macro could be simplified and should also be faster now,
  speeding up startup.
  Eventually this macro can be made superfluous, e.g. by using 1:FB or 0,1^Q::S.

8 files changed, 120 insertions, 68 deletions

diff --git a/src/core-commands.c b/src/core-commands.c
index 4523923..6e39d9a 100644
--- a/src/core-commands.c
+++ b/src/core-commands.c
@@ -259,7 +259,7 @@ teco_state_start_loop_open(teco_machine_main_t *ctx, GError **error)
 	    !teco_expressions_pop_num_calc(&lctx.counter, -1, error))
 		return;
 	lctx.brace_level = teco_brace_level;
-	lctx.pass_through = teco_machine_main_eval_colon(ctx);
+	lctx.pass_through = teco_machine_main_eval_colon(ctx) > 0;
 
 	if (lctx.counter) {
 		/*
@@ -306,7 +306,7 @@ teco_state_start_loop_close(teco_machine_main_t *ctx, GError **error)
 		return;
 	}
 
-	gboolean colon_modified = teco_machine_main_eval_colon(ctx);
+	gboolean colon_modified = teco_machine_main_eval_colon(ctx) > 0;
 
 	/*
 	 * Colon-modified loop ends can be used to
@@ -387,7 +387,7 @@ teco_state_start_break(teco_machine_main_t *ctx, GError **error)
 	teco_bool_t rc;
 	if (!teco_expressions_pop_num_calc(&rc, v, error))
 		return;
-	if (teco_machine_main_eval_colon(ctx))
+	if (teco_machine_main_eval_colon(ctx) > 0)
 		rc = ~rc;
 
 	if (teco_is_success(rc))
@@ -544,9 +544,9 @@ teco_state_start_jump(teco_machine_main_t *ctx, GError **error)
 			                         teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0), 0);
 		teco_interface_ssm(SCI_GOTOPOS, pos, 0);
 
-		if (teco_machine_main_eval_colon(ctx))
+		if (teco_machine_main_eval_colon(ctx) > 0)
 			teco_expressions_push(TECO_SUCCESS);
-	} else if (teco_machine_main_eval_colon(ctx)) {
+	} else if (teco_machine_main_eval_colon(ctx) > 0) {
 		teco_expressions_push(TECO_FAILURE);
 	} else {
 		teco_error_move_set(error, "J");
@@ -588,7 +588,7 @@ teco_state_start_move(teco_machine_main_t *ctx, GError **error)
 		return;
 
 	teco_bool_t rc = teco_move_chars(v);
-	if (teco_machine_main_eval_colon(ctx)) {
+	if (teco_machine_main_eval_colon(ctx) > 0) {
 		teco_expressions_push(rc);
 	} else if (teco_is_failure(rc)) {
 		teco_error_move_set(error, "C");
@@ -613,7 +613,7 @@ teco_state_start_reverse(teco_machine_main_t *ctx, GError **error)
 		return;
 
 	teco_bool_t rc = teco_move_chars(-v);
-	if (teco_machine_main_eval_colon(ctx)) {
+	if (teco_machine_main_eval_colon(ctx) > 0) {
 		teco_expressions_push(rc);
 	} else if (teco_is_failure(rc)) {
 		teco_error_move_set(error, "R");
@@ -664,7 +664,7 @@ teco_state_start_line(teco_machine_main_t *ctx, GError **error)
 		return;
 
 	teco_bool_t rc = teco_move_lines(v);
-	if (teco_machine_main_eval_colon(ctx)) {
+	if (teco_machine_main_eval_colon(ctx) > 0) {
 		teco_expressions_push(rc);
 	} else if (teco_is_failure(rc)) {
 		teco_error_move_set(error, "L");
@@ -690,7 +690,7 @@ teco_state_start_back(teco_machine_main_t *ctx, GError **error)
 		return;
 
 	teco_bool_t rc = teco_move_lines(-v);
-	if (teco_machine_main_eval_colon(ctx)) {
+	if (teco_machine_main_eval_colon(ctx) > 0) {
 		teco_expressions_push(rc);
 	} else if (teco_is_failure(rc)) {
 		teco_error_move_set(error, "B");
@@ -745,7 +745,7 @@ teco_state_start_word(teco_machine_main_t *ctx, GError **error)
 	if (v < 0) {
 		if (teco_current_doc_must_undo())
 			undo__teco_interface_ssm(SCI_GOTOPOS, pos, 0);
-		if (teco_machine_main_eval_colon(ctx))
+		if (teco_machine_main_eval_colon(ctx) > 0)
 			teco_expressions_push(TECO_SUCCESS);
 	} else {
 		teco_interface_ssm(SCI_GOTOPOS, pos, 0);
@@ -841,7 +841,7 @@ teco_state_start_delete_words(teco_machine_main_t *ctx, GError **error)
 		return;
 
 	teco_bool_t rc = teco_delete_words(v);
-	if (teco_machine_main_eval_colon(ctx)) {
+	if (teco_machine_main_eval_colon(ctx) > 0) {
 		teco_expressions_push(rc);
 	} else if (teco_is_failure(rc)) {
 		teco_error_words_set(error, "V");
@@ -866,7 +866,7 @@ teco_state_start_delete_words_back(teco_machine_main_t *ctx, GError **error)
 		return;
 
 	teco_bool_t rc = teco_delete_words(-v);
-	if (teco_machine_main_eval_colon(ctx)) {
+	if (teco_machine_main_eval_colon(ctx) > 0) {
 		teco_expressions_push(rc);
 	} else if (teco_is_failure(rc)) {
 		teco_error_words_set(error, "Y");
@@ -941,7 +941,7 @@ teco_state_start_kill(teco_machine_main_t *ctx, const gchar *cmd, gboolean by_li
 		rc = teco_bool(len >= 0 && from >= 0 && to >= 0);
 	}
 
-	if (teco_machine_main_eval_colon(ctx)) {
+	if (teco_machine_main_eval_colon(ctx) > 0) {
 		teco_expressions_push(rc);
 	} else if (teco_is_failure(rc)) {
 		teco_error_range_set(error, cmd);
@@ -1251,6 +1251,10 @@ teco_state_start_input(teco_machine_main_t *ctx, gunichar chr, GError **error)
 	 * Modifiers
 	 */
 	case '@':
+		if (ctx->modifier_at) {
+			teco_error_modifier_set(error, '@');
+			return NULL;
+		}
 		/*
 		 * @ modifier has syntactic significance, so set it even
 		 * in PARSE_ONLY* modes.
@@ -1263,11 +1267,15 @@ teco_state_start_input(teco_machine_main_t *ctx, gunichar chr, GError **error)
 		return &teco_state_start;
 
 	case ':':
-		if (ctx->mode == TECO_MODE_NORMAL) {
-			if (ctx->parent.must_undo)
-				teco_undo_guint(ctx->__flags);
-			ctx->modifier_colon = TRUE;
+		if (ctx->mode > TECO_MODE_NORMAL)
+			return &teco_state_start;
+		if (ctx->modifier_colon >= 2) {
+			teco_error_modifier_set(error, ':');
+			return NULL;
 		}
+		if (ctx->parent.must_undo)
+			teco_undo_guint(ctx->__flags);
+		ctx->modifier_colon++;
 		return &teco_state_start;
 
 	default:
@@ -1314,7 +1322,7 @@ teco_state_fcommand_loop_start(teco_machine_main_t *ctx, GError **error)
 
 	teco_loop_context_t *lctx = &g_array_index(teco_loop_stack, teco_loop_context_t,
 	                                           teco_loop_stack->len-1);
-	gboolean colon_modified = teco_machine_main_eval_colon(ctx);
+	gboolean colon_modified = teco_machine_main_eval_colon(ctx) > 0;
 
 	if (!lctx->pass_through) {
 		if (colon_modified) {
@@ -1816,7 +1824,7 @@ teco_state_control_glyphs2bytes(teco_machine_main_t *ctx, GError **error)
 	if (!teco_expressions_eval(FALSE, error))
 		return;
 
-	gboolean colon_modified = teco_machine_main_eval_colon(ctx);
+	gboolean colon_modified = teco_machine_main_eval_colon(ctx) > 0;
 
 	if (!teco_expressions_args()) {
 		/*
@@ -2487,7 +2495,7 @@ teco_state_ecommand_eol(teco_machine_main_t *ctx, GError **error)
 	if (teco_expressions_args() > 0) {
 		teco_int_t eol_mode;
 
-		if (teco_machine_main_eval_colon(ctx)) {
+		if (teco_machine_main_eval_colon(ctx) > 0) {
 			teco_int_t v1, v2;
 			if (!teco_expressions_pop_num_calc(&v1, 0, error))
 				return;
@@ -2533,7 +2541,7 @@ teco_state_ecommand_eol(teco_machine_main_t *ctx, GError **error)
 			undo__teco_interface_ssm(SCI_SETEOLMODE,
 			                         teco_interface_ssm(SCI_GETEOLMODE, 0, 0), 0);
 		teco_interface_ssm(SCI_SETEOLMODE, eol_mode, 0);
-	} else if (teco_machine_main_eval_colon(ctx)) {
+	} else if (teco_machine_main_eval_colon(ctx) > 0) {
 		const gchar *eol_seq = teco_eol_get_seq(teco_interface_ssm(SCI_GETEOLMODE, 0, 0));
 		teco_expressions_push(eol_seq);
 	} else {
@@ -2644,7 +2652,7 @@ teco_state_ecommand_encoding(teco_machine_main_t *ctx, GError **error)
 	if (!teco_expressions_eval(FALSE, error))
 		return;
 
-	gboolean colon_modified = teco_machine_main_eval_colon(ctx);
+	gboolean colon_modified = teco_machine_main_eval_colon(ctx) > 0;
 
 	guint old_cp = teco_interface_get_codepage();
 
@@ -2829,7 +2837,7 @@ teco_state_ecommand_encoding(teco_machine_main_t *ctx, GError **error)
 static void
 teco_state_ecommand_exit(teco_machine_main_t *ctx, GError **error)
 {
-	if (teco_machine_main_eval_colon(ctx)) {
+	if (teco_machine_main_eval_colon(ctx) > 0) {
 		if (!teco_ring_save_all_dirty_buffers(error))
 			return;
 	} else {
diff --git a/src/error.h b/src/error.h
index 2df7b89..c51f528 100644
--- a/src/error.h
+++ b/src/error.h
@@ -39,6 +39,7 @@ typedef enum {
 	 * They will mainly be different in their error message.
 	 */
 	TECO_ERROR_SYNTAX,
+	TECO_ERROR_MODIFIER,
 	TECO_ERROR_ARGEXPECTED,
 	TECO_ERROR_CODEPOINT,
 	TECO_ERROR_MOVE,
@@ -74,6 +75,13 @@ teco_error_syntax_set(GError **error, gunichar chr)
 }
 
 static inline void
+teco_error_modifier_set(GError **error, gchar modifier)
+{
+	g_set_error(error, TECO_ERROR, TECO_ERROR_MODIFIER,
+	            "Excess \"%c\"-modifier", modifier);
+}
+
+static inline void
 teco_error_argexpected_set(GError **error, const gchar *cmd)
 {
 	g_set_error(error, TECO_ERROR, TECO_ERROR_ARGEXPECTED,
diff --git a/src/glob.c b/src/glob.c
index a69aa81..e338975 100644
--- a/src/glob.c
+++ b/src/glob.c
@@ -466,7 +466,7 @@ teco_state_glob_filename_done(teco_machine_main_t *ctx, const teco_string_t *str
 	GFileTest file_flags = G_FILE_TEST_EXISTS;
 
 	gboolean matching = FALSE;
-	gboolean colon_modified = teco_machine_main_eval_colon(ctx);
+	gboolean colon_modified = teco_machine_main_eval_colon(ctx) > 0;
 
 	teco_int_t teco_test_mode;
 
diff --git a/src/parser.c b/src/parser.c
index e1bf576..018e35f 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -320,16 +320,17 @@ teco_machine_main_init(teco_machine_main_t *ctx, teco_qreg_table_t *qreg_table_l
 	teco_machine_stringbuilding_init(&ctx->expectstring.machine, '\e', qreg_table_locals, must_undo);
 }
 
-gboolean
+guint
 teco_machine_main_eval_colon(teco_machine_main_t *ctx)
 {
-	if (!ctx->modifier_colon)
-		return FALSE;
+	guint c = ctx->modifier_colon;
+	if (c == 0)
+		return 0;
 
 	if (ctx->parent.must_undo)
 		teco_undo_guint(ctx->__flags);
-	ctx->modifier_colon = FALSE;
-	return TRUE;
+	ctx->modifier_colon = 0;
+	return c;
 }
 
 gboolean
diff --git a/src/parser.h b/src/parser.h
index 1127dcd..20f73fb 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -460,7 +460,12 @@ struct teco_machine_main_t {
 		struct {
 			teco_mode_t mode : 8;
 
-			bool modifier_colon : 1;
+			/** number of `:`-modifiers detected */
+			guint modifier_colon : 2;
+			/**
+			 * Whether the `@`-modifier has been detected.
+			 * This is tracked even in parse-only mode.
+			 */
 			bool modifier_at : 1;
 		};
 		guint __flags;
@@ -503,7 +508,7 @@ void teco_machine_main_init(teco_machine_main_t *ctx,
                             teco_qreg_table_t *qreg_table_locals,
                             gboolean must_undo);
 
-gboolean teco_machine_main_eval_colon(teco_machine_main_t *ctx);
+guint teco_machine_main_eval_colon(teco_machine_main_t *ctx);
 gboolean teco_machine_main_eval_at(teco_machine_main_t *ctx);
 
 gboolean teco_machine_main_step(teco_machine_main_t *ctx,
diff --git a/src/qreg-commands.c b/src/qreg-commands.c
index c36a6b7..0a64b2f 100644
--- a/src/qreg-commands.c
+++ b/src/qreg-commands.c
@@ -256,7 +256,7 @@ teco_state_queryqreg_got_register(teco_machine_main_t *ctx, teco_qreg_t *qreg,
 	if (!teco_expressions_eval(FALSE, error))
 		return NULL;
 
-	if (teco_machine_main_eval_colon(ctx)) {
+	if (teco_machine_main_eval_colon(ctx) > 0) {
 		/* Query Q-Register's existence or string size */
 		if (qreg) {
 			/* get_string() would return the size in bytes */
@@ -366,7 +366,7 @@ teco_state_setqregstring_nobuilding_done(teco_machine_main_t *ctx,
 	if (ctx->mode > TECO_MODE_NORMAL)
 		return &teco_state_start;
 
-	gboolean colon_modified = teco_machine_main_eval_colon(ctx);
+	gboolean colon_modified = teco_machine_main_eval_colon(ctx) > 0;
 
 	if (!teco_expressions_eval(FALSE, error))
 		return NULL;
@@ -578,9 +578,9 @@ teco_state_setqreginteger_got_register(teco_machine_main_t *ctx, teco_qreg_t *qr
 		    !qreg->vtable->set_integer(qreg, v, error))
 			return NULL;
 
-		if (teco_machine_main_eval_colon(ctx))
+		if (teco_machine_main_eval_colon(ctx) > 0)
 			teco_expressions_push(TECO_SUCCESS);
-	} else if (teco_machine_main_eval_colon(ctx)) {
+	} else if (teco_machine_main_eval_colon(ctx) > 0) {
 		teco_expressions_push(TECO_FAILURE);
 	} else {
 		teco_error_argexpected_set(error, "U");
@@ -653,7 +653,7 @@ teco_state_macro_got_register(teco_machine_main_t *ctx, teco_qreg_t *qreg,
 	if (ctx->mode > TECO_MODE_NORMAL)
 		return &teco_state_start;
 
-	if (teco_machine_main_eval_colon(ctx)) {
+	if (teco_machine_main_eval_colon(ctx) > 0) {
 		/* don't create new local Q-Registers if colon modifier is given */
 		if (!teco_qreg_execute(qreg, ctx->qreg_table_locals, error))
 			return NULL;
@@ -710,7 +710,7 @@ teco_state_macrofile_done(teco_machine_main_t *ctx, const teco_string_t *str, GE
 
 	g_autofree gchar *filename = teco_file_expand_path(str->data);
 
-	if (teco_machine_main_eval_colon(ctx)) {
+	if (teco_machine_main_eval_colon(ctx) > 0) {
 		/* don't create new local Q-Registers if colon modifier is given */
 		if (!teco_execute_file(filename, ctx->qreg_table_locals, error))
 			return NULL;
@@ -803,7 +803,7 @@ teco_state_copytoqreg_got_register(teco_machine_main_t *ctx, teco_qreg_t *qreg,
 	};
 	teco_interface_ssm(SCI_GETTEXTRANGEFULL, 0, (sptr_t)&range);
 
-	if (teco_machine_main_eval_colon(ctx)) {
+	if (teco_machine_main_eval_colon(ctx) > 0) {
 		if (!qreg->vtable->append_string(qreg, str, len, error))
 			return NULL;
 	} else {
diff --git a/src/search.c b/src/search.c
index c0398dc..e05a6b9 100644
--- a/src/search.c
+++ b/src/search.c
@@ -686,6 +686,9 @@ teco_state_search_process(teco_machine_main_t *ctx, const teco_string_t *str, gs
 	if (teco_is_failure(search_mode))
 		flags |= G_REGEX_CASELESS;
 
+	if (ctx->modifier_colon == 2)
+		flags |= G_REGEX_ANCHORED;
+
 	/* this is set in teco_state_search_initial() */
 	if (ctx->expectstring.machine.codepage != SC_CP_UTF8) {
 		/* single byte encoding */
@@ -835,7 +838,7 @@ teco_state_search_done(teco_machine_main_t *ctx, const teco_string_t *str, GErro
 	if (!search_reg->vtable->get_integer(search_reg, &search_state, error))
 		return FALSE;
 
-	if (teco_machine_main_eval_colon(ctx))
+	if (teco_machine_main_eval_colon(ctx) > 0)
 		teco_expressions_push(search_state);
 	else if (teco_is_failure(search_state) &&
 	         !teco_loop_stack->len /* not in loop */)
@@ -860,19 +863,20 @@ teco_state_search_done(teco_machine_main_t *ctx, const teco_string_t *str, GErro
 		##__VA_ARGS__ \
 	)
 
-/*$ S search pattern
- * S[pattern]$ -- Search for pattern
- * [n]S[pattern]$
+/*$ S search pattern compare
+ * [n]S[pattern]$ -- Search for pattern
  * -S[pattern]$
  * from,toS[pattern]$
- * :S[pattern]$ -> Success|Failure
  * [n]:S[pattern]$ -> Success|Failure
  * -:S[pattern]$ -> Success|Failure
  * from,to:S[pattern]$ -> Success|Failure
+ * [n]::S[pattern]$ -> Success|Failure
+ * -::S[pattern]$ -> Success|Failure
+ * from,to::S[pattern]$ -> Success|Failure
  *
  * Search for <pattern> in the current buffer/Q-Register.
  * Search order and range depends on the arguments given.
- * By default without any arguments, S will search forward
+ * By default without any arguments, \fBS\fP will search forward
  * from dot till file end.
  * The optional single argument specifies the occurrence
  * to search (1 is the first occurrence, 2 the second, etc.).
@@ -906,10 +910,23 @@ teco_state_search_done(teco_machine_main_t *ctx, const teco_string_t *str, GErro
  * .EX
  * <Sfoo$; ...>
  * .EE
- * Alternatively, S may be colon-modified in which case it returns
+ * Alternatively, \fBS\fP may be colon-modified in which case it returns
  * a condition boolean that may be directly evaluated by a
  * conditional or break-command.
  *
+ * When modified with two colons, the search will be anchored in addition
+ * to returning a condition boolean, i.e. it can be used to perform a string
+ * comparison.
+ * \(lq::S\(rq without arguments compares the pattern against the current
+ * buffer position.
+ * With a single positive integer <n>, \(lq::S\(rq matches <n> repititions
+ * of the given pattern.
+ * With a negative integer <n>, \(lq::S\(rq will match the \fIn\fP-th last
+ * occurrence of the pattern from the beginning of the buffer
+ * (which is not really useful).
+ * With two integer arguments, \(lq::S\(rq compares the pattern against
+ * the corresponding part of the buffer.
+ *
  * In interactive mode, searching will be performed immediately
  * (\(lqsearch as you type\(rq) highlighting matched text
  * on the fly.
@@ -996,12 +1013,12 @@ teco_state_search_all_done(teco_machine_main_t *ctx, const teco_string_t *str, G
  *
  * Search for <pattern> over buffer boundaries.
  * This command is similar to the regular search command
- * (S) but will continue to search for occurrences of
+ * (\fBS\fP) but will continue to search for occurrences of
  * pattern when the end or beginning of the current buffer
  * is reached.
  * Occurrences of <pattern> spanning over buffer boundaries
  * will not be found.
- * When searching forward N will start in the current buffer
+ * When searching forward \fBN\fP will start in the current buffer
  * at dot, continue with the next buffer in the ring searching
  * the entire buffer until it reaches the end of the buffer
  * ring, continue with the first buffer in the ring until
@@ -1009,7 +1026,7 @@ teco_state_search_all_done(teco_machine_main_t *ctx, const teco_string_t *str, G
  * beginning of the buffer up to its current dot.
  * Searching backwards does the reverse.
  *
- * N also differs from S in the interpretation of two arguments.
+ * \fBN\fP also differs from \fBS\fP in the interpretation of two arguments.
  * Using two arguments the search will be bounded between the
  * buffer with number <from>, up to the buffer with number
  * <to>.
@@ -1024,6 +1041,13 @@ teco_state_search_all_done(teco_machine_main_t *ctx, const teco_string_t *str, G
  * buffer numbers greater than the number of buffers in the
  * ring.
  */
+/*
+ * Since N inherits the double-colon semantics from S,
+ * f,t::N will match at the beginning of the given buffers.
+ * [n]::N will behave similar to [n]::S, but can search across
+ * buffer boundaries.
+ * This is probably not very useful in practice, so it's not documented.
+ */
 TECO_DEFINE_STATE_SEARCH(teco_state_search_all,
 	.initial_cb = (teco_state_initial_cb_t)teco_state_search_all_initial
 );
@@ -1088,8 +1112,8 @@ teco_state_search_kill_done(teco_machine_main_t *ctx, const teco_string_t *str,
  * -:FK[pattern]$ -> Success|Failure
  * from,to:FK[pattern]$ -> Success|Failure
  *
- * FK searches for <pattern> just like the regular search
- * command (S) but when found deletes all text from dot
+ * \fBFK\fP searches for <pattern> just like the regular search
+ * command (\fBS\fP) but when found deletes all text from dot
  * up to but not including the found text instance.
  * When searching backwards the characters beginning after
  * the occurrence of <pattern> up to dot are deleted.
@@ -1097,6 +1121,9 @@ teco_state_search_kill_done(teco_machine_main_t *ctx, const teco_string_t *str,
  * In interactive mode, deletion is not performed
  * as-you-type but only on command termination.
  */
+/*
+ * ::FK is possible but doesn't make much sense, so it's undocumented.
+ */
 TECO_DEFINE_STATE_SEARCH(teco_state_search_kill);
 
 static teco_state_t *
@@ -1127,17 +1154,18 @@ teco_state_search_delete_done(teco_machine_main_t *ctx, const teco_string_t *str
 }
 
 /*$ FD
- * FD[pattern]$ -- Delete occurrence of pattern
- * [n]FD[pattern]$
+ * [n]FD[pattern]$ -- Delete occurrence of pattern
  * -FD[pattern]$
  * from,toFD[pattern]$
- * :FD[pattern]$ -> Success|Failure
  * [n]:FD[pattern]$ -> Success|Failure
  * -:FD[pattern]$ -> Success|Failure
  * from,to:FD[pattern]$ -> Success|Failure
+ * [n]::FD[pattern]$ -> Success|Failure
+ * -::FD[pattern]$ -> Success|Failure
+ * from,to::FD[pattern]$ -> Success|Failure
  *
  * Searches for <pattern> just like the regular search command
- * (S) but when found deletes the entire occurrence.
+ * (\fBS\fP) but when found deletes the entire occurrence.
  */
 TECO_DEFINE_STATE_SEARCH(teco_state_search_delete);
 
@@ -1187,22 +1215,23 @@ teco_state_replace_done(teco_machine_main_t *ctx, const teco_string_t *str, GErr
 }
 
 /*$ FS
- * FS[pattern]$[string]$ -- Search and replace
- * [n]FS[pattern]$[string]$
+ * [n]FS[pattern]$[string]$ -- Search and replace
  * -FS[pattern]$[string]$
  * from,toFS[pattern]$[string]$
- * :FS[pattern]$[string]$ -> Success|Failure
  * [n]:FS[pattern]$[string]$ -> Success|Failure
  * -:FS[pattern]$[string]$ -> Success|Failure
  * from,to:FS[pattern]$[string]$ -> Success|Failure
+ * [n]::FS[pattern]$[string]$ -> Success|Failure
+ * -::FS[pattern]$[string]$ -> Success|Failure
+ * from,to::FS[pattern]$[string]$ -> Success|Failure
  *
  * Search for <pattern> just like the regular search command
- * (S) does but replace it with <string> if found.
+ * (\fBS\fP) does but replace it with <string> if found.
  * If <string> is empty, the occurrence will always be
- * deleted so \(lqFS[pattern]$$\(rq is similar to
+ * deleted so \(lqFS[pattern]\fB$$\fP\(rq is similar to
  * \(lqFD[pattern]$\(rq.
  * The global replace register is \fBnot\fP touched
- * by the FS command.
+ * by the \fBFS\fP command.
  *
  * In interactive mode, the replacement will be performed
  * immediately and interactively.
@@ -1291,20 +1320,21 @@ teco_state_replace_default_done(teco_machine_main_t *ctx, const teco_string_t *s
 }
 
 /*$ FR
- * FR[pattern]$[string]$ -- Search and replace with default
- * [n]FR[pattern]$[string]$
+ * [n]FR[pattern]$[string]$ -- Search and replace with default
  * -FR[pattern]$[string]$
  * from,toFR[pattern]$[string]$
- * :FR[pattern]$[string]$ -> Success|Failure
  * [n]:FR[pattern]$[string]$ -> Success|Failure
  * -:FR[pattern]$[string]$ -> Success|Failure
  * from,to:FR[pattern]$[string]$ -> Success|Failure
+ * [n]::FR[pattern]$[string]$ -> Success|Failure
+ * -::FR[pattern]$[string]$ -> Success|Failure
+ * from,to::FR[pattern]$[string]$ -> Success|Failure
  *
- * The FR command is similar to the FS command.
+ * The \fBFR\fP command is similar to the \fBFS\fP command.
  * It searches for <pattern> just like the regular search
- * command (S) and replaces the occurrence with <string>
- * similar to what FS does.
- * It differs from FS in the fact that the replacement
+ * command (\fBS\fP) and replaces the occurrence with <string>
+ * similar to what \fBFS\fP does.
+ * It differs from \fBFS\fP in the fact that the replacement
  * string is saved in the global replacement register
  * \(lq-\(rq.
  * If <string> is empty the string in the global replacement
diff --git a/src/spawn.c b/src/spawn.c
index a0bc7a9..fb7a946 100644
--- a/src/spawn.c
+++ b/src/spawn.c
@@ -463,7 +463,7 @@ teco_state_execute_done(teco_machine_main_t *ctx, const teco_string_t *str, GErr
 		goto gerror;
 	}
 
-	if (teco_machine_main_eval_colon(ctx))
+	if (teco_machine_main_eval_colon(ctx) > 0)
 		teco_expressions_push(TECO_SUCCESS);
 
 	goto cleanup;