From 4ef10c92f44d7ef684784ec8212bcb8d6bea2641 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Sat, 26 Oct 2019 14:25:03 +0300
Subject: [PATCH] array: map() method

---
 vlib/compiler/comptime.v | 39 +++++++++++++++++++++++++++++++++++++++
 vlib/compiler/parser.v   |  4 ++++
 2 files changed, 43 insertions(+)

diff --git a/vlib/compiler/comptime.v b/vlib/compiler/comptime.v
index 709d9d0ae8..6b035b7760 100644
--- a/vlib/compiler/comptime.v
+++ b/vlib/compiler/comptime.v
@@ -374,3 +374,42 @@ fn (p mut Parser) gen_array_filter(str_typ string, method_ph int) {
 	p.check(.rpar)
 	p.close_scope()
 }
+
+fn (p mut Parser) gen_array_map(str_typ string, method_ph int) {
+	/*
+		// V
+		a := [1,2,3,4]
+		b := a.map(it * 2)
+		
+		// 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];
+			_PUSH(tmp2, it * 2, tmp3, int)
+		}
+		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()
+	tmp_elm := p.get_tmp()
+	a := p.expr_var.name
+	map_type, expr := p.tmp_expr()
+	p.cgen.set_placeholder(method_ph,'\narray $tmp = new_array(0, $a .len, ' +
+		'sizeof($map_type));\n')
+	p.genln('for (int i = 0; i < ${a}.len; i++) {')
+	p.genln('$val_type it = (($val_type*)${a}.data)[i];')
+	p.genln('_PUSH(&$tmp, $expr, $tmp_elm, $map_type)')
+	p.genln('}')
+	p.gen(tmp) // TODO why does this `gen()` work?
+	p.check(.rpar)
+	p.close_scope()
+}
diff --git a/vlib/compiler/parser.v b/vlib/compiler/parser.v
index b031c8a6f3..e06d166cee 100644
--- a/vlib/compiler/parser.v
+++ b/vlib/compiler/parser.v
@@ -1947,6 +1947,10 @@ fn (p mut Parser) dot(str_typ_ string, method_ph int) string {
 		p.gen_array_filter(str_typ, method_ph)
 		return str_typ
 	}	
+	else if field_name == 'map' && str_typ.starts_with('array_') {
+		p.gen_array_map(str_typ, method_ph)
+		return str_typ
+	}	
 	
 	fname_tidx := p.cur_tok_index()
 	p.fgen(field_name)