[Nano-devel] [PATCH V2] possible new feature: a tab command to define what the Tab key produces

[Benno Schulenberg]

V2: Indenting and unindenting a marked region should work too: it must
add and remove the exact contents of the specified tab string.  But this
also means that, when a tab string is specfied, the unindenting is no
longer flexible: it will no longer see tabsize spaces as equivalent to
a tab, nor the other way around.

The 'tab' command is syntax-specific and should be followed by a string
containing the character(s) that a single press of the <Tab> key should
produce -- most likely a single TAB or a small bunch of spaces, but any
string is allowed.  This overrides the 'tabstospaces' option/toggle.

This addresses https://savannah.gnu.org/bugs/?53661,
and addresses https://savannah.gnu.org/bugs/?54760,
and addresses part of https://savannah.gnu.org/bugs/?54775.
---
 src/nano.h   |  2 ++
 src/rcfile.c |  3 +++
 src/text.c   | 24 ++++++++++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/src/nano.h b/src/nano.h
index 3007881d..b53d4e86 100644
--- a/src/nano.h
+++ b/src/nano.h
@@ -227,6 +227,8 @@ typedef struct syntaxtype {
                /* The list of libmagic results that this syntax applies to. */
        char *linter;
                /* The command with which to lint this type of file. */
+       char *tab;
+               /* What the Tab key should produce; NULL for default behavior. 
*/
 #ifdef ENABLE_COMMENT
        char *comment;
                /* The line comment prefix (and postfix) for this type of file. 
*/
diff --git a/src/rcfile.c b/src/rcfile.c
index d8a2d1fe..6c434a96 100644
--- a/src/rcfile.c
+++ b/src/rcfile.c
@@ -300,6 +300,7 @@ void parse_syntax(char *ptr)
        live_syntax->headers = NULL;
        live_syntax->magics = NULL;
        live_syntax->linter = NULL;
+       live_syntax->tab = NULL;
 #ifdef ENABLE_COMMENT
        live_syntax->comment = mallocstrcpy(NULL, GENERAL_COMMENT_CHARACTER);
 #endif
@@ -993,6 +994,8 @@ void parse_rcfile(FILE *rcstream, bool syntax_only)
                        parse_colors(ptr, NANO_REG_EXTENDED | REG_ICASE);
                else if (strcasecmp(keyword, "linter") == 0)
                        pick_up_name("linter", ptr, &live_syntax->linter);
+               else if (strcasecmp(keyword, "tab") == 0)
+                       pick_up_name("tab", ptr, &live_syntax->tab);
                else if (syntax_only && (strcasecmp(keyword, "set") == 0 ||
                                                                
strcasecmp(keyword, "unset") == 0 ||
                                                                
strcasecmp(keyword, "bind") == 0 ||
diff --git a/src/text.c b/src/text.c
index 8302c7dd..a89180f6 100644
--- a/src/text.c
+++ b/src/text.c
@@ -267,6 +267,11 @@ void do_cut_next_word(void)
  * of spaces that a tab would normally take up. */
 void do_tab(void)
 {
+#ifdef ENABLE_COLOR
+       if (openfile->syntax && openfile->syntax->tab)
+               do_output(openfile->syntax->tab, strlen(openfile->syntax->tab), 
TRUE);
+       else
+#endif
 #ifndef NANO_TINY
        if (ISSET(TABS_TO_SPACES)) {
                char *spaces = charalloc(tabsize + 1);
@@ -332,6 +337,11 @@ void do_indent(void)
        indentation = charalloc(tabsize + 1);
 
        /* Set the indentation to either a bunch of spaces or a single tab. */
+#ifdef ENABLE_COLOR
+       if (openfile->syntax && openfile->syntax->tab)
+               indentation = mallocstrcpy(indentation, openfile->syntax->tab);
+       else
+#endif
        if (ISSET(TABS_TO_SPACES)) {
                charset(indentation, ' ', tabsize);
                indentation[tabsize] = '\0';
@@ -364,6 +374,20 @@ size_t length_of_white(const char *text)
 {
        size_t bytes_of_white = 0;
 
+#ifdef ENABLE_COLOR
+       if (openfile->syntax && openfile->syntax->tab) {
+               size_t thelength = strlen(openfile->syntax->tab);
+
+               while (bytes_of_white < thelength) {
+                       if (text[bytes_of_white] != 
openfile->syntax->tab[bytes_of_white])
+                               return 0;
+                       bytes_of_white++;
+               }
+
+               return thelength;
+       }
+#endif
+
        while (TRUE) {
                if (*text == '\t')
                        return ++bytes_of_white;
-- 
2.19.1