cgen: add for map

vlib/v/ast/ast.v

@@ -406,16 +406,18 @@ pub:
 
 pub struct ForInStmt {
 pub:
-	key_var      string
-	val_var      string
-	cond         Expr
-	is_range     bool
-	high         Expr // `10` in `for i in 0..10 {`
-	stmts        []Stmt
-	pos          token.Position
+	key_var   string
+	val_var   string
+	cond      Expr
+	is_range  bool
+	high      Expr // `10` in `for i in 0..10 {`
+	stmts     []Stmt
+	pos       token.Position
 mut:
-	element_type table.Type
-	kind         table.Kind // array/map/string
+	key_type  table.Type
+	val_type  table.Type
+	cond_type table.Type
+	kind      table.Kind // array/map/string
 }
 
 pub struct ForCStmt {

vlib/v/checker/checker.v

@@ -590,6 +590,7 @@ fn (c mut Checker) stmt(node ast.Stmt) {
 						else {
 							table.int_type}
 	}
+					it.key_type = key_type
 					scope.override_var(ast.Var{
 						name: it.key_var
 						typ: key_type
@@ -600,8 +601,9 @@ fn (c mut Checker) stmt(node ast.Stmt) {
 					typ_sym := c.table.get_type_symbol(typ)
 					c.error('for in: cannot index $typ_sym.name', it.pos)
 				}
+				it.cond_type = typ
 				it.kind = sym.kind
-				it.element_type = value_type
+				it.val_type = value_type
 				scope.override_var(ast.Var{
 					name: it.val_var
 					typ: value_type

vlib/v/gen/cgen.v

@@ -366,13 +366,34 @@ fn (g mut Gen) stmt(node ast.Stmt) {
 				g.write('for (int $i = 0; $i < ')
 				g.expr(it.cond)
 				g.writeln('.len; $i++) {')
-				styp := g.typ(it.element_type)
+				styp := g.typ(it.val_type)
 				g.write('$styp $it.val_var = (($styp*)')
 				g.expr(it.cond)
 				g.writeln('.data)[$i];')
 				g.stmts(it.stmts)
 				g.writeln('}')
 			}
+			else if it.kind == .map {
+				// `for num in nums {`
+				g.writeln('// FOR IN')
+				cond_styp := g.typ(it.cond_type)
+				key_styp := g.typ(it.key_type)
+				val_styp := g.typ(it.val_type)
+				keys_tmp := 'keys_' + g.new_tmp_var()
+				idx := g.new_tmp_var()
+				key := if it.key_var == '' { g.new_tmp_var() } else { it.key_var }
+				g.write('array_$key_styp $keys_tmp = map_keys(&')
+				g.expr(it.cond)
+				g.writeln(');')
+				g.writeln('for (int $idx = 0; $idx < ${keys_tmp}.len; $idx++) {')
+				g.writeln('$key_styp $key = (($key_styp*)${keys_tmp}.data)[$idx];')
+				zero := g.type_default(it.val_type)
+				g.write('$val_styp $it.val_var = (*($val_styp*)map_get3(')
+				g.expr(it.cond)
+				g.writeln(', $key, &($val_styp[]){ $zero }));')
+				g.stmts(it.stmts)
+				g.writeln('}')
+			}
 		}
 		ast.ForStmt {
 			g.write('while (')