array: optimized generic filter()

v.v

@@ -12,6 +12,8 @@ import (
 fn main() {
 	// There's no `flags` module yet, so args have to be parsed manually
 	args := compiler.env_vflags_and_os_args()
+	//options := args.filter(it.starts_with('-'))
+	
 	// Print the version and exit.
 	if '-v' in args || '--version' in args || 'version' in args {
 		version_hash := compiler.vhash()

vlib/builtin/array.v

@@ -332,7 +332,7 @@ pub fn (a []char) index(v char) int {
 ////////////// FILTER //////////////
 
 // Creates a new array with all elements that pass the test implemented by the provided function.
-pub fn (a  []string) filter(predicate fn(p_val string, p_i int, p_arr []string) bool) []string
+pub fn (a  []string) filter2(predicate fn(p_val string, p_i int, p_arr []string) bool) []string
 {
 	mut res := []string
 	for i := 0; i < a.len; i++  {
@@ -343,7 +343,7 @@ pub fn (a  []string) filter(predicate fn(p_val string, p_i int, p_arr []string)
 	return res
 }
 
-pub fn (a []int) filter(predicate fn(p_val, p_i int, p_arr []int) bool) []int
+pub fn (a []int) filter2(predicate fn(p_val, p_i int, p_arr []int) bool) []int
 {
 	mut res := []int
 	for i := 0; i < a.len; i++  {

vlib/builtin/array_test.v

@@ -303,14 +303,14 @@ fn callback_2(val string, index int, arr []string) bool {
 	return val.len >= 2
 }
 
-fn test_filter() {
+fn test_filter2() {
 	a := [1, 2, 3, 4, 5, 6]
-	b := a.filter(callback_1)
+	b := a.filter2(callback_1)
 	assert b[0] == 2
 	assert b[1] == 3
 
 	c := ['v', 'is', 'awesome']
-	d := c.filter(callback_2)
+	d := c.filter2(callback_2)
 	assert d[0] == 'is'
 	assert d[1] == 'awesome'
 }
@@ -338,3 +338,15 @@ fn test_reduce() {
 	assert f == -6
 	assert g == -7
 }
+
+fn test_filter() {
+	a := [1, 2, 3, 4, 5, 6]
+	b := a.filter(it % 2 == 0)
+	assert b[0] == 2
+	assert b[1] == 4
+	assert b[2] == 6
+	c := ['v', 'is', 'awesome']
+	d := c.filter(it.len > 1)
+	assert d[0] == 'is'
+	assert d[1] == 'awesome'
+}	

vlib/compiler/parser.v

@@ -2104,6 +2104,50 @@ fn (p mut Parser) dot(str_typ_ string, method_ph int) string {
 		return 'void'
 	}
 	field_name := p.lit
+	if field_name == 'filter' && str_typ.starts_with('array_') {
+		/*
+			// V
+			a := [1,2,3,4]
+			b := a.filter(it % 2 == 0)
+			
+			// C
+			array_int a = ...;
+			array_int tmp2 = new_array(0, 4, 4);
+			for (int i = 0; i < a.len; i++) {
+				int it = ((int*)a.data)[i];
+				if (it % 2 == 0) array_push(&tmp2, &it);
+			}
+			array_int b = tmp2;
+		*/
+		val_type:=str_typ.right(6)
+		p.open_scope()
+		p.register_var(Var{
+			name: 'it'
+			typ: val_type
+		})
+		p.next()
+		p.check(.lpar)
+		p.cgen.resetln('')
+		tmp := p.get_tmp()
+		a := p.expr_var.name
+		p.cgen.set_placeholder(method_ph,'\n$str_typ $tmp = new_array(0, $a .len,sizeof($val_type));\n')
+		p.genln('for (int i = 0; i < ${a}.len; i++) {')
+		p.genln('$val_type it = (($val_type*)${a}.data)[i];')
+		if val_type == 'string'{
+		p.genln('println(it);')
+		}
+		p.gen('if (')
+		p.bool_expression()
+		p.genln(') array_push(&$tmp, &it);')
+		//p.genln(') array_push(&$tmp, &((($val_type*)${a}.data)[i]));')
+		//p.genln(') array_push(&$tmp, ${a}.data + i * ${a}.element_size);')
+		p.genln('}')
+		p.gen(tmp) // TODO why does this `gen()` work?
+		p.check(.rpar)
+		p.close_scope()
+		return str_typ
+	}	
+	
 	fname_tidx := p.cur_tok_index()
 	p.fgen(field_name)
 	//p.log('dot() field_name=$field_name typ=$str_typ')

vlib/compiler/token.v

@@ -93,6 +93,7 @@ enum TokenKind {
 	key_import_const
 	key_in
 	key_interface
+	//key_it
 	key_match
 	key_module
 	key_mut
@@ -189,6 +190,7 @@ fn build_token_str() []string {
 	s[TokenKind.key_assert] = 'assert'
 	s[TokenKind.key_struct] = 'struct'
 	s[TokenKind.key_if] = 'if'
+	//s[TokenKind.key_it] = 'it'
 	s[TokenKind.key_else] = 'else'
 	s[TokenKind.key_return] = 'return'
 	s[TokenKind.key_module] = 'module'

vlib/compiler/vtest.v

@@ -153,7 +153,7 @@ pub fn v_test_v(args_before_test string){
 	//////////////////////////////////////////////////////////////
 	println('\nBuilding examples...')
 	mut es := new_test_sesion( args_before_test )
-	es.files << os.walk_ext(parent_dir+'/examples','.v').filter(stable_example)
+	es.files << os.walk_ext(parent_dir+'/examples','.v').filter2(stable_example)
 	es.test()
 	println( es.benchmark.total_message('building examples') )
 	//////////////////////////////////////////////////////////////