feat: Checked subscript

closes #304 Left operand of binary operation was not checked for optional
buzz-language · Jun 26, 2024 · fccb4e4 · fccb4e4
1 parent db013da
commit fccb4e4
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Showing 13 changed files with 172 additions and 38 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -9,6 +9,14 @@ const tuple = .{ "john", "james" };
 
 tuples.@"0" == "john";
 ```
+- Checked subscript access to list and strings:
+```buzz
+var list = [1, 2, 3];
+
+list[?10] == null;
+
+"hello"[?20] == null;
+```
 
 ## Modified
 - Enum can now have `rg`, `ud`, `void`, `pat` has value type

diff --git a/src/Ast.zig b/src/Ast.zig
@@ -655,6 +655,7 @@ pub const Subscript = struct {
     subscripted: Node.Index,
     index: Node.Index,
     value: ?Node.Index,
+    checked: bool,
 };
 
 pub const Throw = struct {
@@ -1203,6 +1204,10 @@ pub fn toValue(self: Self, node: Node.Index, gc: *GarbageCollector) Error!Value
                         const index: usize = @intCast(key.integer());
 
                         if (index < 0 or index >= list.items.items.len) {
+                            if (components.checked) {
+                                break :subscript Value.Null;
+                            }
+
                             return Error.OutOfBound;
                         }
 
@@ -1218,6 +1223,10 @@ pub fn toValue(self: Self, node: Node.Index, gc: *GarbageCollector) Error!Value
                         const index: usize = @intCast(key.integer());
 
                         if (index < 0 or index >= str.string.len) {
+                            if (components.checked) {
+                                break :subscript Value.Null;
+                            }
+
                             return Error.OutOfBound;
                         }
 

diff --git a/src/Codegen.zig b/src/Codegen.zig
@@ -537,6 +537,24 @@ fn generateBinary(self: *Self, node: Ast.Node.Index, breaks: ?*Breaks) Error!?*o
         else => unreachable,
     }
 
+    if (components.operator != .QuestionQuestion and components.operator != .EqualEqual and components.operator != .BangEqual) {
+        if (left_type.optional) {
+            self.reporter.reportErrorAt(
+                .binary_operand_type,
+                self.ast.tokens.get(locations[components.left]),
+                "Binary operand can't be optional",
+            );
+        }
+
+        if (right_type.optional) {
+            self.reporter.reportErrorAt(
+                .binary_operand_type,
+                self.ast.tokens.get(locations[components.right]),
+                "Binary operand can't be optional",
+            );
+        }
+    }
+
     switch (components.operator) {
         .QuestionQuestion => {
             if (!left_type.optional) {
@@ -3569,7 +3587,11 @@ fn generateSubscript(self: *Self, node: Ast.Node.Index, breaks: ?*Breaks) Error!
 
         try self.emitOpCode(location, set_code);
     } else {
-        try self.emitOpCode(location, get_code);
+        try self.emitCodeArg(
+            location,
+            get_code,
+            if (components.checked) 1 else 0,
+        );
     }
 
     try self.patchOptJumps(node);

diff --git a/src/Jit.zig b/src/Jit.zig
@@ -3567,6 +3567,10 @@ fn generateSubscript(self: *Self, node: Ast.Node.Index) Error!?m.MIR_op_t {
                 &[_]m.MIR_op_t{
                     subscripted,
                     index,
+                    m.MIR_new_uint_op(
+                        self.ctx,
+                        if (components.checked) 1 else 0,
+                    ),
                 },
             );
 
@@ -3585,6 +3589,10 @@ fn generateSubscript(self: *Self, node: Ast.Node.Index) Error!?m.MIR_op_t {
                     m.MIR_new_reg_op(self.ctx, self.state.?.vm_reg.?),
                     subscripted,
                     index_val,
+                    m.MIR_new_uint_op(
+                        self.ctx,
+                        if (components.checked) 1 else 0,
+                    ),
                 },
             );
 

diff --git a/src/Parser.zig b/src/Parser.zig
@@ -3303,6 +3303,7 @@ fn subscript(self: *Self, can_assign: bool, subscripted: Ast.Node.Index) Error!A
     const start_location = self.current_token.? - 1;
 
     const subscript_type_def = self.ast.nodes.items(.type_def)[subscripted];
+    const checked = try self.match(.Question);
     const index = try self.expression(false);
     const index_type_def = self.ast.nodes.items(.type_def)[index];
 
@@ -3321,13 +3322,15 @@ fn subscript(self: *Self, can_assign: bool, subscripted: Ast.Node.Index) Error!A
         if (!type_def.optional) {
             switch (type_def.def_type) {
                 .Placeholder => {
-                    const placeholder_resolved_type: obj.ObjTypeDef.TypeUnion = .{
-                        .Placeholder = obj.PlaceholderDef.init(self.gc.allocator, self.current_token.? - 1),
-                    };
                     const placeholder = try self.gc.type_registry.getTypeDef(
                         .{
                             .def_type = .Placeholder,
-                            .resolved_type = placeholder_resolved_type,
+                            .resolved_type = .{
+                                .Placeholder = obj.PlaceholderDef.init(
+                                    self.gc.allocator,
+                                    self.current_token.? - 1,
+                                ),
+                            },
                         },
                     );
 
@@ -3366,12 +3369,16 @@ fn subscript(self: *Self, can_assign: bool, subscripted: Ast.Node.Index) Error!A
             .tag = .Subscript,
             .location = start_location,
             .end_location = self.current_token.? - 1,
-            .type_def = subscripted_type_def,
+            .type_def = if (subscripted_type_def != null and checked)
+                try subscripted_type_def.?.cloneOptional(&self.gc.type_registry)
+            else
+                subscripted_type_def,
             .components = .{
                 .Subscript = .{
                     .index = index,
                     .value = value,
                     .subscripted = subscripted,
+                    .checked = checked,
                 },
             },
         },

diff --git a/src/buzz_api.zig b/src/buzz_api.zig
@@ -426,11 +426,15 @@ export fn bz_objStringConcat(vm: *VM, obj_string: Value, other: Value) Value {
     ) catch @panic("Could not concat strings")).toValue();
 }
 
-export fn bz_objStringSubscript(vm: *VM, obj_string: Value, index_value: Value) Value {
+export fn bz_objStringSubscript(vm: *VM, obj_string: Value, index_value: Value, checked: bool) Value {
     const str = ObjString.cast(obj_string.obj()).?;
     const index = index_value.integer();
 
     if (index < 0) {
+        if (checked) {
+            return Value.Null;
+        }
+
         bz_throw(
             vm,
             (vm.gc.copyString("Out of bound string access.") catch unreachable).toValue(),
@@ -444,6 +448,10 @@ export fn bz_objStringSubscript(vm: *VM, obj_string: Value, index_value: Value)
     if (str_index < str.string.len) {
         return (vm.gc.copyString(&([_]u8{str.string[str_index]})) catch unreachable).toValue();
     } else {
+        if (checked) {
+            return Value.Null;
+        }
+
         bz_throw(
             vm,
             (vm.gc.copyString("Out of bound str access.") catch unreachable).toValue(),
@@ -564,8 +572,18 @@ export fn bz_valueToList(value: Value) *ObjList {
     return ObjList.cast(value.obj()).?;
 }
 
-export fn bz_listGet(self: Value, index: usize) Value {
-    return ObjList.cast(self.obj()).?.items.items[index];
+export fn bz_listGet(self: Value, index: i32, checked: bool) Value {
+    const list = ObjList.cast(self.obj()).?;
+
+    if (index < 0 or index >= list.items.items.len) {
+        if (checked) {
+            return Value.Null;
+        } else {
+            @panic("Out of bound list access.");
+        }
+    }
+
+    return list.items.items[@intCast(index)];
 }
 
 export fn bz_listSet(vm: *VM, self: Value, index: usize, value: Value) void {

diff --git a/src/disassembler.zig b/src/disassembler.zig
@@ -249,9 +249,6 @@ pub fn disassembleInstruction(chunk: *Chunk, offset: usize) usize {
         .OP_MOD,
         .OP_UNWRAP,
         .OP_GET_ENUM_CASE_VALUE,
-        .OP_GET_LIST_SUBSCRIPT,
-        .OP_GET_MAP_SUBSCRIPT,
-        .OP_GET_STRING_SUBSCRIPT,
         .OP_SET_LIST_SUBSCRIPT,
         .OP_SET_MAP_SUBSCRIPT,
         .OP_THROW,
@@ -306,6 +303,9 @@ pub fn disassembleInstruction(chunk: *Chunk, offset: usize) usize {
         .OP_GET_STRING_PROPERTY,
         .OP_GET_PATTERN_PROPERTY,
         .OP_GET_OBJECT_PROPERTY,
+        .OP_GET_LIST_SUBSCRIPT,
+        .OP_GET_STRING_SUBSCRIPT,
+        .OP_GET_MAP_SUBSCRIPT,
         => byteInstruction(instruction, chunk, offset),
 
         .OP_OBJECT,

diff --git a/src/jit_extern_api.zig b/src/jit_extern_api.zig
@@ -103,7 +103,7 @@ pub const ExternApi = enum {
                 self.pname(),
                 1,
                 &[_]m.MIR_type_t{m.MIR_T_U64},
-                3,
+                4,
                 &[_]m.MIR_var_t{
                     .{
                         .type = m.MIR_T_P,
@@ -120,6 +120,11 @@ pub const ExternApi = enum {
                         .name = "index_value",
                         .size = undefined,
                     },
+                    .{
+                        .type = m.MIR_T_U8,
+                        .name = "checked",
+                        .size = undefined,
+                    },
                 },
             ),
             .bz_closure => m.MIR_new_proto_arr(
@@ -218,7 +223,31 @@ pub const ExternApi = enum {
                     },
                 },
             ),
-            .bz_listGet, .bz_mapGet => m.MIR_new_proto_arr(
+            .bz_listGet => m.MIR_new_proto_arr(
+                ctx,
+                self.pname(),
+                1,
+                &[_]m.MIR_type_t{m.MIR_T_U64},
+                3,
+                &[_]m.MIR_var_t{
+                    .{
+                        .type = m.MIR_T_U64,
+                        .name = "list",
+                        .size = undefined,
+                    },
+                    .{
+                        .type = m.MIR_T_I32,
+                        .name = "index",
+                        .size = undefined,
+                    },
+                    .{
+                        .type = m.MIR_T_U8,
+                        .name = "checked",
+                        .size = undefined,
+                    },
+                },
+            ),
+            .bz_mapGet => m.MIR_new_proto_arr(
                 ctx,
                 self.pname(),
                 1,

diff --git a/src/lib/buzz_api.zig b/src/lib/buzz_api.zig
@@ -324,7 +324,7 @@ pub const ObjString = opaque {
     pub extern fn bz_objStringToString(obj_string: *ObjString, len: *usize) ?[*]const u8;
     pub extern fn bz_objStringToValue(obj_string: *ObjString) Value;
     pub extern fn bz_objStringConcat(vm: *VM, obj_string: Value, other: Value) Value;
-    pub extern fn bz_objStringSubscript(vm: *VM, obj_string: Value, index_value: Value) Value;
+    pub extern fn bz_objStringSubscript(vm: *VM, obj_string: Value, index_value: Value, checked: bool) Value;
     pub extern fn bz_toString(vm: *VM, value: Value) Value;
     pub extern fn bz_getStringProperty(vm: *VM, method_idx: usize) Value;
     pub extern fn bz_stringNext(vm: *VM, string_value: Value, index: *Value) Value;
@@ -340,7 +340,7 @@ pub const ObjList = opaque {
     pub extern fn bz_newList(vm: *VM, of_type: Value) Value;
     pub extern fn bz_listAppend(vm: *VM, list: Value, value: Value) void;
     pub extern fn bz_valueToList(value: Value) *ObjList;
-    pub extern fn bz_listGet(self: Value, index: usize) Value;
+    pub extern fn bz_listGet(self: Value, index: i32, checked: bool) Value;
     pub extern fn bz_listSet(vm: *VM, self: Value, index: usize, value: Value) void;
     pub extern fn bz_listLen(self: *ObjList) usize;
     pub extern fn bz_listConcat(vm: *VM, list: Value, other_list: Value) Value;

diff --git a/src/lib/buzz_buffer.zig b/src/lib/buzz_buffer.zig
@@ -519,7 +519,11 @@ inline fn rawWriteZ(
 
     var index = at;
     for (0..values.bz_listLen()) |i| {
-        const value = api.ObjList.bz_listGet(values_value, i);
+        const value = api.ObjList.bz_listGet(
+            values_value,
+            @intCast(i),
+            false,
+        );
 
         if (!ctx.vm.bz_checkBuzzType(value, zig_type.?, obj_typedef)) {
             return false;
@@ -591,7 +595,11 @@ inline fn rawWriteStruct(
 
     var index = at;
     for (0..values.bz_listLen()) |i| {
-        const value = api.ObjList.bz_listGet(values_value, i);
+        const value = api.ObjList.bz_listGet(
+            values_value,
+            @intCast(i),
+            false,
+        );
 
         if (!value.bz_valueIs(type_def_value).boolean()) {
             var msg = std.ArrayList(u8).init(api.VM.allocator);

diff --git a/src/lib/buzz_os.zig b/src/lib/buzz_os.zig
@@ -159,7 +159,11 @@ pub export fn execute(ctx: *api.NativeCtx) c_int {
     const len = argv.bz_listLen();
     var i: usize = 0;
     while (i < len) : (i += 1) {
-        const arg = api.ObjList.bz_listGet(argv_value, i);
+        const arg = api.ObjList.bz_listGet(
+            argv_value,
+            @intCast(i),
+            false,
+        );
         var arg_len: usize = 0;
         var arg_str = arg.bz_valueToString(&arg_len);