cgen: fix slices

vlib/v/ast/ast.v

@@ -499,6 +499,8 @@ pub struct RangeExpr {
 pub:
 	low      Expr
 	high     Expr
+	has_high bool
+	has_low  bool
 }
 
 pub struct CastExpr {

vlib/v/gen/cgen.v

@@ -598,11 +598,22 @@ fn (g mut Gen) index_expr(node ast.IndexExpr) {
 			g.write('array_slice(')
 			g.expr(node.left)
 			g.write(', ')
-			// g.expr(it.low)
+			if it.has_low {
+				g.expr(it.low)
+			}
+			else {
 				g.write('0')
+			}
 			g.write(', ')
+			if it.has_high {
 				g.expr(it.high)
+			}
+			else {
+				g.expr(node.left)
+				g.write('.len')
+			}
 			g.write(')')
+			return
 		}
 		else {}
 	}
@@ -618,7 +629,7 @@ fn (g mut Gen) index_expr(node ast.IndexExpr) {
 			g.write(')')
 		}
 		else if sym.kind == .string {
-			g.write('string_get(')
+			g.write('string_at(')
 			g.expr(node.left)
 			g.write(', ')
 			g.expr(node.index)

vlib/v/gen/tests/1.c

@@ -66,6 +66,8 @@ i < 10; i++) {
 		1, 2, 3,
 	});
 	array_int nums2 = array_slice(nums, 0, 2);
+	array_int nums3 = array_slice(nums, 1, 2);
+	array_int nums4 = array_slice(nums, 1, nums.len);
 	int number = array_get(nums, 0);
 	array_bool bools = new_array_from_c_array(2, 2, sizeof(array_bool), (bool[]){
 		true, false,

vlib/v/gen/tests/1.vv

@@ -61,6 +61,8 @@ fn foo(a int) {
 	}
 	nums := [1,2,3]
 	nums2 := nums[..2]
+	nums3 := nums[1..2]
+	nums4 := nums[1..]
 	number := nums[0]
 	bools := [true, false]
 	users := [User{}]

vlib/v/parser/parser.v

@@ -817,7 +817,9 @@ fn (p mut Parser) prefix_expr() ast.PrefixExpr {
 fn (p mut Parser) index_expr(left ast.Expr) ast.IndexExpr {
 	// left == `a` in `a[0]`
 	p.next() // [
+	mut has_low := true
 	if p.tok.kind == .dotdot {
+		has_low = false
 		// [..end]
 		p.next()
 		high := p.expr(0)
@@ -828,15 +830,18 @@ fn (p mut Parser) index_expr(left ast.Expr) ast.IndexExpr {
 			index: ast.RangeExpr{
 				low: ast.Expr{}
 				high: high
+				has_high: true
 			}
 		}
 	}
 	expr := p.expr(0) // `[expr]` or  `[expr..]`
+	mut has_high := false
 	if p.tok.kind == .dotdot {
 		// [start..end] or [start..]
 		p.check(.dotdot)
 		mut high := ast.Expr{}
 		if p.tok.kind != .rsbr {
+			has_high = true
 			high = p.expr(0)
 		}
 		p.check(.rsbr)
@@ -846,6 +851,8 @@ fn (p mut Parser) index_expr(left ast.Expr) ast.IndexExpr {
 			index: ast.RangeExpr{
 				low: expr
 				high: high
+				has_high: has_high
+				has_low: has_low
 			}
 		}
 	}