compiler: @VMODULE

doc/docs.md

@@ -1274,16 +1274,31 @@ NB: For now you have to use one flag per line:
 
 You can also add C code, in your V module. For example, lets say that your C code is located in a folder named 'c' inside your module folder. Then:
 
+* Put a v.mod file inside the toplevel folder of your module (if you
+created your module with `v create` you already have v.mod file). For
+example:
 ```v
-#flag -I @VMODULE/c
-#flag @VMODULE/c/implementation.o
-#include "header.h"
+Module {
+	name: 'mymodule',
+	description: 'My nice module wraps a simple C library.',
+	version: '0.0.1'
+	dependencies: []
+}
 ```
 
-... will make V look for an compiled .o file in your module folder/c/implementation.o .
+* Add these lines to the top of your module:
+```v
+#flag -I @VROOT/c
+#flag @VROOT/c/implementation.o
+#include "header.h"
+```
+NB: @VROOT will be replaced by V with the *nearest parent folder, where there is a v.mod file*.
+
+The instructions above will make V look for an compiled .o file in your module folder/c/implementation.o .
 If V finds it, the .o file will get linked to the main executable, that used the module.
-If it does not find it, V assumes that there is a `@VMODULE/c/implementation.c` file,
+If it does not find it, V assumes that there is a `@VROOT/c/implementation.c` file,
 and tries to compile it to a .o file, then will use that.
+
 This allows you to have C code, that is contained in a V module, so that its distribution is easier.
 You can see a complete example for using C code in a V wrapper module here:
 [minimal V project, that has a module, which contains C code](https://github.com/vlang/v/tree/master/vlib/compiler/tests/project_with_c_code)

examples/.gitignore

@@ -14,6 +14,7 @@
 /fibonacci
 /sqlite
 /path_tracing
+/gg2
 *.ppm
 empty_gg_freetype
 game_of_life/life_gg

v.mod

@@ -0,0 +1,8 @@
+#V Project#
+
+Module {
+	name: 'V',
+	description: 'The V programming language.',
+	version: '0.1.25'
+	dependencies: []
+}

vlib/compiler/aparser.v

@@ -176,10 +176,11 @@ fn (v mut V) new_parser_from_file(path string) Parser {
 		}
 	}
 	mut p := v.new_parser(new_scanner_file(path))
+	path_dir := os.realpath(filepath.dir(path))
 	p = {
 		p |
 		file_path:path,
-		file_path_dir:filepath.dir(path),
+		file_path_dir: path_dir,
 		file_name:path.all_after(filepath.separator),
 		file_platform:path_platform,
 		file_pcguard:path_pcguard,

vlib/compiler/comptime.v

@@ -21,7 +21,7 @@ fn (p mut Parser) comp_time() {
 		}
 		name := p.check_name()
 		p.fspace()
-    
+
 		if name in supported_platforms {
 			os := os_from_string(name)
 			ifdef_name := os_name_to_ifdef(name)
@@ -127,13 +127,13 @@ fn (p mut Parser) comp_time() {
 			//
 			// The ? sign, means that `custom` is optional, and when
 			// it is not present at all at the command line, then the
-			// block will just be ignored, instead of erroring.			
+			// block will just be ignored, instead of erroring.
 			if p.tok == .question {
 				p.next()
 			}
 			p.comptime_if_block('CUSTOM_DEFINE_${name}', not)
-		} else {			
-			if p.tok == .question {				
+		} else {
+			if p.tok == .question {
 				p.next()
 				p.comptime_if_block('CUSTOM_DEFINE_${name}', not)
 			}else{
@@ -242,12 +242,18 @@ fn (p mut Parser) chash() {
 	if hash.starts_with('flag ') {
 		if p.first_pass() {
 			mut flag := hash[5..]
-			// expand `@VROOT` `@VMOD` to absolute path
-			flag = flag.replace('@VMODULE', p.file_path_dir)
-			flag = flag.replace('@VROOT', p.vroot)
-			flag = flag.replace('@VPATH', p.pref.vpath)
-			flag = flag.replace('@VLIB_PATH', p.pref.vlib_path)
-			flag = flag.replace('@VMOD', v_modules_path)
+			// expand `@VROOT` to its absolute path
+			if flag.contains('@VROOT') {
+				vmod_file_location := p.v.mod_file_cacher.get( p.file_path_dir )
+				if vmod_file_location.vmod_file.len == 0 {
+					// There was no actual v.mod file found.
+					p.error_with_token_index('To use @VROOT, you need' +
+						' to have a "v.mod" file in ${p.file_path_dir},' +
+						' or in one of its parent folders.',
+						p.cur_tok_index() - 1)
+				}
+				flag = flag.replace('@VROOT', vmod_file_location.vmod_folder )
+			}
 			// p.log('adding flag "$flag"')
 			_ = p.table.parse_cflag(flag, p.mod, p.v.pref.compile_defines_all ) or {
 				p.error_with_token_index(err, p.cur_tok_index() - 1)
@@ -561,4 +567,3 @@ pub fn (e &$typ.name) has(flag $typ.name) bool { return int(*e)&(1 << int(flag))
 	p.cgen.fns << 'void ${typ.name}_toggle($typ.name *e, $typ.name flag);'
 	p.cgen.fns << 'bool ${typ.name}_has($typ.name *e, $typ.name flag);'
 }
-

vlib/compiler/main.v

@@ -36,6 +36,7 @@ enum Pass {
 
 pub struct V {
 pub mut:
+	mod_file_cacher     &ModFileCacher // used during lookup for v.mod to support @VROOT
 	out_name_c          string // name of the temporary C file
 	files               []string // all V files that need to be parsed and compiled
 	compiled_dir        string // contains os.realpath() of the dir of the final file beeing compiled, or the dir itself when doing `v .`
@@ -68,6 +69,7 @@ pub fn new_v(pref &pref.Preferences) &V {
 	compiled_dir:=if os.is_dir(rdir) { rdir } else { filepath.dir(rdir) }
 
 	return &V{
+		mod_file_cacher: new_mod_file_cacher()
 		compiled_dir:compiled_dir// if os.is_dir(rdir) { rdir } else { filepath.dir(rdir) }
 		table: new_table(pref.obfuscate)
 		out_name_c: out_name_c
@@ -815,8 +817,8 @@ pub fn (v mut V) parse_lib_imports() {
 			if mod in done_imports {
 				continue
 			}
-			import_path := v.find_module_path(mod) or {
-				v.parsers[i].error_with_token_index('cannot import module "$mod" (not found)', v.parsers[i].import_table.get_import_tok_idx(mod))
+			import_path := v.parsers[i].find_module_path(mod) or {
+				v.parsers[i].error_with_token_index('cannot import module "$mod" (not found)\n$err', v.parsers[i].import_table.get_import_tok_idx(mod))
 				break
 			}
 			vfiles := v.v_files_from_dir(import_path)

vlib/compiler/modules.v

@@ -182,21 +182,21 @@ fn (v mut V) set_module_lookup_paths() {
 	}
 }
 
-fn (v &V) find_module_path(mod string) ?string {
-	mod_path := v.module_path(mod)
-	for lookup_path in v.module_lookup_paths {
+fn (p &Parser) find_module_path(mod string) ?string {
+	mod_path := p.v.module_path(mod)
+	for lookup_path in p.v.module_lookup_paths {
 		try_path := filepath.join(lookup_path,mod_path)
-		if v.pref.is_verbose {
+		if p.v.pref.is_verbose {
 			println('  >> trying to find $mod in $try_path ...')
 		}
 		if os.is_dir(try_path) {
-			if v.pref.is_verbose {
+			if p.v.pref.is_verbose {
 				println('  << found $try_path .')
 			}
 			return try_path
 		}
 	}
-	return error('module "$mod" not found')
+	return error('module "$mod" not found in ${p.v.module_lookup_paths}')
 }
 
 [inline]

vlib/compiler/tests/project_with_c_code/.v.mod.stop

@@ -0,0 +1,4 @@
+Do not delete this file.
+It is used by V to stop the lookup for v.mod,
+so that the top level vlib/v.mod is not found,
+if you delete mod1/v.mod .

vlib/compiler/tests/project_with_c_code/mod1/v.mod

@@ -0,0 +1,7 @@
+#V Module#
+
+Module {
+	name: 'mod1',
+	description: 'A simple module, containing C code.',
+	dependencies: []
+}

vlib/compiler/tests/project_with_c_code/mod1/wrapper.v

@@ -1,7 +1,7 @@
 module mod1
 
-#flag -I @VMODULE/c
-#flag @VMODULE/c/implementation.o
+#flag -I @VROOT/c
+#flag @VROOT/c/implementation.o
 
 #include "header.h"
 

vlib/compiler/v_mod_cache.v

@@ -0,0 +1,153 @@
+module compiler
+
+import os
+import filepath
+
+
+// This file provides a caching mechanism for seeking quickly whether a
+// given folder has a v.mod file in it or in any of its parent folders.
+//
+// ModFileCacher.get(folder) works in such a way, that given this tree:
+// examples/hanoi.v
+// vlib/v.mod
+// vlib/compiler/tests/project_with_c_code/mod1/v.mod
+// vlib/compiler/tests/project_with_c_code/mod1/wrapper.v
+// -----------------
+// ModFileCacher.get('examples')
+// => ModFileAndFolder{'', 'examples'}
+// ModFileCacher.get('vlib/compiler/tests')
+// => ModFileAndFolder{'vlib/v.mod', 'vlib'}
+// ModFileCacher.get('vlib/compiler')
+// => ModFileAndFolder{'vlib/v.mod', 'vlib'}
+// ModFileCacher.get('vlib/project_with_c_code/mod1')
+// => ModFileAndFolder{'vlib/project_with_c_code/mod1/v.mod', 'vlib/project_with_c_code/mod1'}
+
+
+struct ModFileAndFolder {
+	// vmod_file contains the full path of the found 'v.mod' file, or ''
+	// if no 'v.mod' file was found in file_path_dir, or in its parent folders.
+	vmod_file string
+
+	// vmod_folder contains the file_path_dir, if there is no 'v.mod' file in
+	// *any* of the parent folders, otherwise it is the first parent folder,
+	// where a v.mod file was found.
+	vmod_folder string
+}
+
+struct ModFileCacher {
+mut:
+	cache map[string]ModFileAndFolder
+	// folder_files caches os.ls(key)
+	folder_files map[string][]string
+}
+
+fn new_mod_file_cacher() &ModFileCacher {
+	return &ModFileCacher{}
+}
+
+fn (mcache &ModFileCacher) dump() {
+	$if debug {
+		eprintln('ModFileCacher DUMP:')
+		eprintln('	 ModFileCacher.cache:')
+		for k,v in mcache.cache {
+			eprintln('	 K: ${k:-32s} | V: "${v.vmod_file:32s}" | "${v.vmod_folder:32s}" ')
+		}
+		eprintln('	 ModFileCacher.folder_files:')
+		for k,v in mcache.folder_files {
+			eprintln('	 K: ${k:-32s} | V: ${v.str()}')
+		}
+	}
+}
+
+fn (mcache mut ModFileCacher) get(mfolder string) ModFileAndFolder {
+	if mfolder in mcache.cache {
+		return mcache.cache[ mfolder ]
+	}
+	traversed_folders, res := mcache.traverse( mfolder )
+	for tfolder in traversed_folders {
+		mcache.add( tfolder, res )
+	}
+	return res
+}
+
+fn (cacher mut ModFileCacher) add(path string, result ModFileAndFolder) {
+	cacher.cache[ path ] = result
+}
+
+fn (mcache mut ModFileCacher) traverse(mfolder string) ([]string, ModFileAndFolder) {
+	mut cfolder := mfolder
+	mut folders_so_far := [cfolder]
+	mut levels := 0
+	for {
+		$if debug {
+			eprintln('pdir2vmod mfolder: ${mfolder:-32s} | cfolder: ${cfolder:-20s} | levels: $levels')
+		}
+		if levels > 255 {
+			break
+		}
+		if cfolder == '/' || cfolder == '' {
+			break
+		}
+		if cfolder in mcache.cache {
+			res := mcache.cache[ cfolder ]
+			if res.vmod_file.len == 0 {
+				mcache.mark_folders_as_vmod_free( folders_so_far )
+			}else{
+				mcache.mark_folders_with_vmod( folders_so_far, res )
+			}
+			return []string, res
+		}
+		files := mcache.get_files( cfolder )
+		if 'v.mod' in files {
+			// TODO: actually read the v.mod file and parse its contents to see
+			// if its source folder is different
+			res := ModFileAndFolder{ vmod_file: filepath.join( cfolder, 'v.mod'), vmod_folder: cfolder }
+			$if debug {
+				eprintln('FOUND v.mod:')
+				eprintln(' ModFileAndFolder{ vmod_file: $res.vmod_file , vmod_folder: $res.vmod_folder } ')
+			}
+			return folders_so_far, res
+		}
+		if mcache.check_for_stop( cfolder, files ) {
+			break
+		}
+		cfolder = filepath.basedir( cfolder )
+		folders_so_far << cfolder
+		levels++
+	}
+	mcache.mark_folders_as_vmod_free( folders_so_far )
+	return [mfolder], ModFileAndFolder{ vmod_file: '', vmod_folder: mfolder }
+}
+
+fn (mcache mut ModFileCacher) mark_folders_with_vmod( folders_so_far []string, vmod ModFileAndFolder ) {
+	for f in folders_so_far {
+		mcache.add( f, vmod )
+	}
+}
+
+fn (mcache mut ModFileCacher) mark_folders_as_vmod_free( folders_so_far []string ) {
+	// No need to check these folders anymore,
+	// because their parents do not contain v.mod files
+	for f in folders_so_far {
+		mcache.add( f, ModFileAndFolder{ vmod_file: '', vmod_folder: f } )
+	}
+}
+
+const ( MOD_FILE_STOP_PATHS = ['.git', '.hg', '.svn', '.v.mod.stop' ] )
+fn (mcache &ModFileCacher) check_for_stop(cfolder string, files []string) bool {
+	for i in MOD_FILE_STOP_PATHS {
+		if i in files {
+			return true
+		}
+	}
+	return false
+}
+
+fn (mcache mut ModFileCacher) get_files(cfolder string) []string {
+	if cfolder in mcache.folder_files {
+		return mcache.folder_files[ cfolder ]
+	}
+	files := os.ls(cfolder) or { return [] }
+	mcache.folder_files[ cfolder ] = files
+	return files
+}