tools, examples: add --only-watch=*.v option to v watch (#18974)

cmd/tools/vwatch.v

@@ -95,6 +95,7 @@ mut:
 	ignore_exts     []string // extensions of files that will be ignored, even if they change (useful for sqlite.db files for example)
 	cmd_before_run  string   // a command to run before each re-run
 	cmd_after_run   string   // a command to run after each re-run
+	only_watch      []string // If not empty, *all* files that trigger updates, should match *at least one* of these s.match_glob() patterns. This is also triggered for vweb apps, to monitor for just *.v,*.js,*.css,*.html in vweb projects.
 }
 
 [if debug_vwatch ?]
@@ -106,6 +107,33 @@ fn (context &Context) str() string {
 	return 'Context{ pid: ${context.pid}, is_worker: ${context.is_worker}, check_period_ms: ${context.check_period_ms}, vexe: ${context.vexe}, opts: ${context.opts}, is_exiting: ${context.is_exiting}, vfiles: ${context.vfiles}'
 }
 
+fn (mut context Context) is_ext_ignored(pf string, pf_ext string) bool {
+	for ipattern in context.ignore_exts {
+		if pf_ext.match_glob(ipattern) {
+			return true
+		}
+	}
+	if pf_ext in ['', '.so', '.a'] {
+		// on unix, the executables saved by compilers, usually do not have extensions at all, and shared libs are .so
+		return true
+	}
+	if pf_ext in ['.exe', '.dll', '.def'] {
+		// on windows, files with these extensions will be generated by the compiler
+		return true
+	}
+	// ignore common backup files saved by editors like emacs/jed/vim:
+	if pf_ext == '.bak' {
+		return true
+	}
+	if pf.starts_with('.#') {
+		return true
+	}
+	if pf.ends_with('~') {
+		return true
+	}
+	return false
+}
+
 fn (mut context Context) get_stats_for_affected_vfiles() []VFileStat {
 	if context.affected_paths.len == 0 {
 		mut apaths := map[string]bool{}
@@ -121,34 +149,63 @@ fn (mut context Context) get_stats_for_affected_vfiles() []VFileStat {
 		vfiles := os.execute(cmd)
 		if vfiles.exit_code == 0 {
 			paths_trimmed := vfiles.output.trim_space()
-			reported_used_files := paths_trimmed.split('\n')
+			reported_used_files := paths_trimmed.split_any('\n')
 			$if trace_reported_used_files ? {
 				context.elog('reported_used_files: ${reported_used_files}')
 			}
 			paths << reported_used_files
 		}
+		mut is_vweb_found := false
 		for vf in paths {
 			apaths[os.real_path(os.dir(vf))] = true
+			if vf.contains('vweb.v') {
+				is_vweb_found = true
+			}
+		}
+
+		if is_vweb_found {
+			if !os.args.any(it.starts_with('--only-watch')) {
+				// vweb is often used with SQLite .db or .sqlite3 files right next to the executable/source,
+				// that are updated by the vweb app, causing a restart of the app, which in turn causes the
+				// browser to reload the current page, that probably triggered the update in the first place.
+				// Note that the problem is not specific to SQLite, any database that stores its files in the
+				// current (project) folder, will also cause this.
+				println('`v watch` detected that you are compiling a vweb project.')
+				println('   Because of that, the `--only-watch=*.v,*.html,*.css,*.js` flag was also implied.')
+				println('   In result, `v watch` will ignore changes to other files.')
+				println('   Add your own --only-watch filter, if you wish to override that choice.')
+				println('')
+				context.only_watch = '*.v,*.html,*.css,*.js'.split_any(',')
+			}
 		}
 		context.affected_paths = apaths.keys()
 		// context.elog('vfiles paths to be scanned: $context.affected_paths')
 	}
-	// scan all files in the found folders
+	// scan all files in the found folders:
 	mut newstats := []VFileStat{}
 	for path in context.affected_paths {
 		mut files := os.ls(path) or { []string{} }
-		for pf in files {
+		next_file: for pf in files {
+			pf_path := os.join_path_single(path, pf)
+			if context.only_watch.len > 0 {
+				// in the whitelist mode, first only allow files, which match at least one of the patterns in context.only_watch:
+				mut matched_pattern_idx := -1
+				for ow_pattern_idx, ow_pattern in context.only_watch {
+					if pf_path.match_glob(ow_pattern) {
+						matched_pattern_idx = ow_pattern_idx
+						context.elog('> ${@METHOD} matched --only-watch pattern: ${ow_pattern}, for file: ${pf_path}')
+						break
+					}
+				}
+				if matched_pattern_idx == -1 {
+					context.elog('> ${@METHOD} --only-watch ignored file: ${pf_path}')
+					continue
+				}
+			}
+			// by default allow everything, except very specific extensions (backup files, executables etc):
 			pf_ext := os.file_ext(pf).to_lower()
-			if pf_ext in ['', '.bak', '.exe', '.dll', '.so', '.def'] {
+			if context.is_ext_ignored(pf, pf_ext) {
-				continue
+				context.elog('> ${@METHOD} ignored extension: ${pf_ext}, for file: ${pf_path}')
-			}
-			if pf_ext in context.ignore_exts {
-				continue
-			}
-			if pf.starts_with('.#') {
-				continue
-			}
-			if pf.ends_with('~') {
 				continue
 			}
 			f := os.join_path(path, pf)
@@ -323,19 +380,21 @@ fn main() {
 	// Options after `run` should be ignored, since they are intended for the user program, not for the watcher.
 	// For example, `v watch run x.v -a -b -k', should pass all of -a -b -k to the compiled and run program.
 	only_watch_options, has_run := all_before('run', all_args_after_watch_cmd)
+
 	mut fp := flag.new_flag_parser(only_watch_options)
 	fp.application('v watch')
 	fp.version('0.0.2')
 	fp.description('Collect all .v files needed for a compilation, then re-run the compilation when any of the source changes.')
 	fp.arguments_description('[--silent] [--clear] [--ignore .db] [--add /path/to/a/file.v] [run] program.v')
 	fp.allow_unknown_args()
-	fp.limit_free_args_to_at_least(1)!
+
 	context.is_worker = fp.bool('vwatchworker', 0, false, 'Internal flag. Used to distinguish vwatch manager and worker processes.')
 	context.silent = fp.bool('silent', `s`, false, 'Be more silent; do not print the watch timestamp before each re-run.')
 	context.clear_terminal = fp.bool('clear', `c`, false, 'Clears the terminal before each re-run.')
 	context.keep_running = fp.bool('keep', `k`, false, 'Keep the program running. Restart it automatically, if it exits by itself. Useful for gg/ui apps.')
-	context.add_files = fp.string('add', `a`, '', 'Add more files to be watched. Useful with `v watch -add=/tmp/feature.v run cmd/v /tmp/feature.v`, if you change *both* the compiler, and the feature.v file.').split(',')
+	context.add_files = fp.string('add', `a`, '', 'Add more files to be watched. Useful with `v watch --add=/tmp/feature.v run cmd/v /tmp/feature.v`, if you change *both* the compiler, and the feature.v file.').split_any(',')
-	context.ignore_exts = fp.string('ignore', `i`, '', 'Ignore files having these extensions. Useful with `v watch -ignore=.db run server.v`, if your server writes to an sqlite.db file in the same folder.').split(',')
+	context.ignore_exts = fp.string('ignore', `i`, '', 'Ignore files having these extensions. Useful with `v watch --ignore=.db run server.v`, if your server writes to an sqlite.db file in the same folder.').split_any(',')
+	context.only_watch = fp.string('only-watch', `o`, '', 'Watch only files matching these globe patterns. Example for a markdown renderer project: `v watch --only-watch=*.v,*.md run .`').split_any(',')
 	show_help := fp.bool('help', `h`, false, 'Show this help screen.')
 	context.cmd_before_run = fp.string('before', 0, '', 'A command to execute *before* each re-run.')
 	context.cmd_after_run = fp.string('after', 0, '', 'A command to execute *after* each re-run.')
@@ -351,6 +410,7 @@ fn main() {
 	context.opts << all_args_before_watch_cmd
 	context.opts << remaining_options
 	if has_run {
+		context.opts << 'run'
 		context.opts << all_after('run', all_args_after_watch_cmd)
 	}
 	context.elog('>>> context.pid: ${context.pid}')
@@ -360,6 +420,7 @@ fn main() {
 	context.elog('>>> context.clear_terminal: ${context.clear_terminal}')
 	context.elog('>>> context.add_files: ${context.add_files}')
 	context.elog('>>> context.ignore_exts: ${context.ignore_exts}')
+	context.elog('>>> context.only_watch: ${context.only_watch}')
 	if context.is_worker {
 		context.worker_main()
 	} else {
@@ -407,7 +468,7 @@ fn all_before(needle string, all []string) ([]string, bool) {
 	if needle_pos == -1 {
 		return all, false
 	}
-	return all#[..needle_pos + 1], true
+	return all#[..needle_pos], true
 }
 
 fn all_after(needle string, all []string) []string {

examples/vwatch/cli_clock/main.v

@@ -0,0 +1,14 @@
+import time
+// This example demonstrates how to use `v watch` for simple CLI apps.
+
+fn main() {
+	println('Run with: `v watch run examples/vwatch/cli_clock`,')
+	println('then modify timer.v in your editor.')
+	println('The application will be restarted,')
+	println('as soon as you save your changes.')
+	println('')
+	for {
+		println('The time is now: ${time.now()}')
+		time.sleep(1000 * time.millisecond)
+	}
+}

examples/vwatch/web_server/.gitignore

@@ -0,0 +1,4 @@
+*
+!.gitignore
+!main.v
+

examples/vwatch/web_server/main.v

@@ -0,0 +1,65 @@
+module main
+
+// This example demonstrates how to use `v watch` for vweb apps, that use sqlite .db files.
+//
+// Note 1: while developing services, it is useful to also add the `--keep` option of `v watch`,
+// which will restart the app right away, even when it exits on its own.
+//
+// Note 2: vweb supports a special live reload mode, where it will make the browser to check for server
+// restarts, and it will trigger a refresh of the current page, right after that is detected.
+//
+// The above means, that to get the most optimal prototyping experience for vweb apps, use:
+// `v -d vweb_livereload watch --only-watch=*.v,*.html,*.css,*.js --keep run .`
+import os
+import vweb
+import db.sqlite
+
+fn mydb() !sqlite.DB {
+	return sqlite.connect(os.resource_abs_path('app.db'))
+}
+
+struct State {
+mut:
+	counter int
+}
+
+struct App {
+	vweb.Context
+mut:
+	state shared State
+}
+
+pub fn (mut app App) index() vweb.Result {
+	mut c := 0
+	lock app.state {
+		app.state.counter++
+		c = app.state.counter
+	}
+	visits := app.update_db() or { 0 }
+	return app.html('<!doctype html><html><body>
+	<br/>Current request counter, after the server restart: ${c}.
+	<br/>Total stored visits: ${visits}
+	</body></html>')
+}
+
+fn (mut app App) update_db() !int {
+	mut db := mydb()!
+	db.exec('INSERT INTO visits (created_at) VALUES ("")')
+	visits := db.q_int('SELECT count(*) FROM visits')
+	db.close()!
+	return visits
+}
+
+fn main() {
+	println('App demonstrating the use of `vweb` & `db.sqlite` together.')
+	println('For best prototyping experience, run with:')
+	println('`v -d vweb_livereload watch --keep run examples/vwatch/web_server/`')
+	println('')
+	mut db := mydb()!
+	db.exec('CREATE TABLE visits (id integer primary key AUTOINCREMENT, created_at timestamp default current_timestamp);')
+	db.exec('CREATE TRIGGER INSERT_visits AFTER INSERT ON visits BEGIN
+	  UPDATE visits SET created_at = datetime("now", "localtime") WHERE rowid = new.rowid ;
+	END')
+	db.close()!
+	vweb.run(&App{}, 19123)
+}

vlib/v/help/common/watch.txt

@@ -13,16 +13,22 @@ Options:
 
   -c, --clear            Clears the terminal before each re-run.
 
-  -a, --add <string>     Add more files to be watched.
+  -a, --add <string>     Add more files to be watched (separated by ,).
                          Useful with `v watch -add=feature.v run cmd/v feature.v`,
                          when you want to change *both* the V compiler,
                          and the `feature.v` file.
 
-  -i, --ignore <string>  Ignore files having these extensions.
+  -i, --ignore <string>  Ignore files having these extensions (separated by ,)
                          Useful with `v watch -ignore=.db run vwebserver.v`,
                          if your `vwebserver` writes to an sqlite.db file in
                          the same folder.
 
+  -o, --only-watch <string>
+                         Watch only files matching these glob patterns
+                         The patterns are separated by `,`. Example for
+                         a markdown renderer project:
+                             v watch --only-watch=*.v,*.md run .
+
   --before <string>      A command to execute *before* each re-run.
                          Example: --before 'v wipe-cache'