implementing more native functions

samples/native_power.lox

@@ -0,0 +1,3 @@
+print power(str2num("3"),str2num("3"));
+
+print str2num("3") + str2num("4");

src/native.zig

@@ -0,0 +1,64 @@
+const std = @import("std");
+
+const Obj = @import("./object.zig").Obj;
+const Value = @import("./values.zig").Value;
+const VM = @import("./vm.zig").VM;
+
+pub fn clock(vm: *VM, arg_count: usize, args: []Value) Value {
+    _ = vm;
+    _ = arg_count;
+    _ = args;
+
+    const ts = std.time.milliTimestamp();
+    return Value.number_val(@floatFromInt(ts));
+}
+
+pub fn power(vm: *VM, arg_count: usize, args: []Value) Value {
+    _ = vm;
+
+    if (arg_count != 2) {
+        std.debug.print("power() is expecting 2 arguments.\n", .{});
+        return Value.nil_val();
+    }
+
+    if (!args[0].is_number() or !args[0].is_number()) {
+        std.debug.print("args must be numbers.\n", .{});
+        return Value.nil_val();
+    }
+
+    const result_f64: f64 = std.math.pow(f64, args[0].as_number(), args[1].as_number());
+
+    return Value.number_val(result_f64);
+}
+
+pub fn str2num(vm: *VM, arg_count: usize, args: []Value) Value {
+    _ = vm;
+
+    if (arg_count != 1 or !args[0].is_string()) {
+        std.debug.print("str2num() is expecting 1 string argument.\n", .{});
+        return Value.nil_val();
+    }
+
+    const result = std.fmt.parseFloat(f64, args[0].as_cstring()) catch {
+        std.debug.print("invalid string for number.\n", .{});
+        return Value.nil_val();
+    };
+
+    return Value.number_val(result);
+}
+
+pub fn num2str(vm: *VM, arg_count: usize, args: []Value) Value {
+    if (arg_count != 1 or !args[0].is_number()) {
+        std.debug.print("num2str() is expecting 1 number argument.\n", .{});
+        return Value.nil_val();
+    }
+
+    const str = std.fmt.allocPrint(vm.allocator, "{d}", .{args[0].as_number()}) catch {
+        std.debug.print("unable to convert number to string.\n", .{});
+        return Value.nil_val();
+    };
+
+    const result = Obj.String.new(vm.allocator, str);
+
+    return Value.obj_val(result);
+}

src/object.zig

@@ -4,6 +4,7 @@ const Allocator = std.mem.Allocator;
 
 const Chunk = @import("./chunk.zig").Chunk;
 const Value = @import("./values.zig").Value;
+const VM = @import("./vm.zig").VM;
 
 const compute_hash = @import("./utils.zig").compute_hash;
 
@@ -13,7 +14,7 @@ pub const ObjType = enum {
     Native,
 };
 
-pub const NativeFn = *const fn (arg_count: usize, args: []Value) Value;
+pub const NativeFn = *const fn (vm: *VM, arg_count: usize, args: []Value) Value;
 
 pub const Obj = struct {
     kind: ObjType,

src/vm.zig

@@ -12,6 +12,8 @@ const ObjType = @import("./object.zig").ObjType;
 const NativeFn = @import("./object.zig").NativeFn;
 const Table = @import("./table.zig").Table;
 
+const natives = @import("./native.zig");
+
 const compile = @import("./compile.zig").compile;
 const compute_hash = @import("./utils.zig").compute_hash;
 
@@ -56,7 +58,9 @@ pub const VM = struct {
     }
 
     pub fn init_vm(self: *VM) void {
-        self.define_native("clock", clock_native);
+        self.define_native("clock", natives.clock);
+        self.define_native("power", natives.power);
+        self.define_native("str2num", natives.str2num);
     }
 
     pub fn destroy(self: *VM) void {
@@ -386,8 +390,9 @@ pub const VM = struct {
                 ObjType.Native => {
                     const native_obj: *Obj.Native = callee.as_obj().as_native();
                     const value = native_obj.native(
+                        self,
                         arg_count,
-                        self.stack[self.current_frame().slots_idx - arg_count .. self.current_frame().slots_idx],
+                        self.stack[self.stack_top - arg_count .. self.stack_top],
                     );
                     self.stack_top -= arg_count + 1;
                     _ = try self.push(value);
@@ -431,11 +436,4 @@ pub const VM = struct {
         _ = self.pop();
         _ = self.pop();
     }
-
-    pub fn clock_native(arg_count: usize, args: []Value) Value {
-        const ts = std.time.milliTimestamp();
-        _ = arg_count;
-        _ = args;
-        return Value.number_val(@floatFromInt(ts));
-    }
 };