Add README, build CI and gif

.github/workflows/build.yml

@@ -0,0 +1,21 @@
+name: build
+
+on: [push, pull_request, workflow_dispatch]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Setup and configure
+      run: |
+        sudo apt-get install -y autoconf automake autopoint gcc gettext git groff make pkg-config texinfo libncurses5-dev
+        ./autogen.sh
+        ./configure
+
+    - name: Build
+      run: make -j
+
+    - name: Check
+      run: make check

README.md

@@ -0,0 +1,149 @@
+# GNU nano (6.2) - Set Tabsize Dynamically
+
+[![build](https://github.com/davidhcefx/GNU-nano-6.2_Set-Tabsize-Dynamically/actions/workflows/build.yml/badge.svg)](https://github.com/davidhcefx/GNU-nano-6.2_Set-Tabsize-Dynamically/actions/workflows/build.yml)
+
+Some files use *two spaces* for indentation (eg. [HTML](https://www.w3schools.com/html/html5_syntax.asp)), while others use *four* (eg. [Python](https://peps.python.org/pep-0008/#indentation)). In the middle of editing a file, I always wish I could change the **tab width** without reopening the file (= loss of history). This patch achieves our goal!
+
+## Usage
+
+For example, bind `M-4` to `settabsize` in your rcfile:
+
+```nanorc
+bind M-4 settabsize main
+```
+
+then you can change tabsize on the fly\!
+
+<img src="demo.gif" alt=" demo set to different tab sizes" width=80%>
+
+
+## How to compile
+
+*Please refer to [README.GIT](/README.GIT) for more details.*
+
+1. Install the dependencies: `apt install autoconf automake autopoint gcc gettext git groff make pkg-config texinfo libncurses5-dev`
+
+2. Run `./autogen.sh`.
+
+3. After that, just do the normal `./configure`, `make` and `make install`.
+
+
+## Patch for Nano v6.2
+```patch
+From 9c8893604886abbfaefa15229c91308d067390a9 Mon Sep 17 00:00:00 2001
+From: davidhcefx <[email protected]>
+Date: Mon, 27 May 2024 15:33:20 +0800
+Subject: [PATCH] Feature: change tabsize dynamically
+
+---
+ doc/nanorc.5     |  3 +++
+ src/global.c     |  4 ++++
+ src/prototypes.h |  1 +
+ src/rcfile.c     |  2 ++
+ src/text.c       | 22 ++++++++++++++++++++++
+ 5 files changed, 32 insertions(+)
+
+diff --git a/doc/nanorc.5 b/doc/nanorc.5
+index ad712e30..c0b77135 100644
+--- a/doc/nanorc.5
++++ b/doc/nanorc.5
+@@ -693,6 +693,9 @@ the line, column, and character positions.
+ Counts and reports on the status bar the number of lines, words,
+ and characters in the current buffer (or in the marked region).
+ .TP
++.B settabsize
++Prompts for a new tabsize to be set.
++.TP
+ .B execute
+ Prompts for a program to execute.  The program's output will be inserted
+ into the current buffer (or into a new buffer when \fBM\-F\fR is toggled).
+diff --git a/src/global.c b/src/global.c
+index 0a32f139..4521f78c 100644
+--- a/src/global.c
++++ b/src/global.c
+@@ -623,6 +623,7 @@ void shortcut_init(void)
+ 	const char *wordcount_gist =
+ 		N_("Count the number of lines, words, and characters");
+ 	const char *suspend_gist = N_("Suspend the editor (return to the shell)");
++	const char *settabsize_gist = N_("Set new tabsize");
+ #endif
+ 	const char *refresh_gist = N_("Refresh (redraw) the current screen");
+ #ifdef ENABLE_WORDCOMPLETION
+@@ -978,6 +979,8 @@ void shortcut_init(void)
+ #ifndef NANO_TINY
+ 	add_to_funcs(count_lines_words_and_characters, MMAIN,
+ 		N_("Word Count"), WITHORSANS(wordcount_gist), TOGETHER, VIEW);
++	add_to_funcs(do_set_tabsize, MMAIN,
++		N_("Set Tabsize"), WITHORSANS(settabsize_gist), TOGETHER, NOVIEW);
+ #endif
+
+ 	add_to_funcs(do_verbatim_input, MMAIN,
+@@ -1355,6 +1358,7 @@ void shortcut_init(void)
+ 	add_to_sclist(MEXECUTE, "^Z", 0, do_suspend, 0);
+ 	add_to_sclist(MMAIN, "^Z", 0, suggest_ctrlT_ctrlZ, 0);
+ 	add_to_sclist(MMAIN, "M-D", 0, count_lines_words_and_characters, 0);
++	add_to_sclist(MMAIN, "M-4", 0, do_set_tabsize, 0);
+ #else
+ 	add_to_sclist(MMAIN, "M-H", 0, do_help, 0);
+ #endif
+diff --git a/src/prototypes.h b/src/prototypes.h
+index cf79680e..eb6de305 100644
+--- a/src/prototypes.h
++++ b/src/prototypes.h
+@@ -519,6 +519,7 @@ void do_formatter(void);
+ #endif
+ #ifndef NANO_TINY
+ void count_lines_words_and_characters(void);
++void do_set_tabsize(void);
+ #endif
+ void do_verbatim_input(void);
+ void complete_a_word(void);
+diff --git a/src/rcfile.c b/src/rcfile.c
+index 049a2886..222bc5af 100644
+--- a/src/rcfile.c
++++ b/src/rcfile.c
+@@ -321,6 +321,8 @@ keystruct *strtosc(const char *input)
+ 		s->func = do_find_bracket;
+ 	else if (!strcmp(input, "wordcount"))
+ 		s->func = count_lines_words_and_characters;
++	else if (!strcmp(input, "settabsize"))
++		s->func = do_set_tabsize;
+ 	else if (!strcmp(input, "recordmacro"))
+ 		s->func = record_macro;
+ 	else if (!strcmp(input, "runmacro"))
+diff --git a/src/text.c b/src/text.c
+index 85d1bd40..79512d45 100644
+--- a/src/text.c
++++ b/src/text.c
+@@ -2969,6 +2969,28 @@ void count_lines_words_and_characters(void)
+ 						words, P_("word", "words", words),
+ 						chars, P_("character", "characters", chars));
+ }
++
++/* Prompt user to set the new tabsize. We use the spell menu because
++ * it has no functions. */
++void do_set_tabsize(void)
++{
++	ssize_t new_tabsize = -1;
++	int response = do_prompt(MSPELL, "", NULL, edit_refresh, "New tabsize");
++
++	/* Cancel if no answer provided. */
++	if (response != 0) {
++		statusbar(_("Cancelled"));
++		return;
++	}
++
++	if (!parse_num(answer, &new_tabsize) || new_tabsize <= 0) {
++		statusline(AHEM, _("Requested tab size \"%s\" is invalid"), answer);
++		return;
++	}
++
++	tabsize = new_tabsize;
++	statusline(REMARK, _("Tabsize set to %d"), tabsize);
++}
+ #endif /* !NANO_TINY */
+
+ /* Get verbatim input. */
+-- 
+2.30.2
+```