`package reflect`; fix substring type bug; fix scoping rules for `using` on procedure parameter

5 files changed, 392 insertions, 58 deletions

diff --git a/core/reflect/reflect.odin b/core/reflect/reflect.odin
new file mode 100644
index 000000000..ecc2e7362
--- /dev/null
+++ b/core/reflect/reflect.odin
@@ -0,0 +1,285 @@
+package reflect
+
+import "core:runtime"
+import "core:mem"
+
+
+Type_Kind :: enum {
+	Invalid,
+
+	Named,
+	Integer,
+	Rune,
+	Float,
+	Complex,
+	String,
+	Boolean,
+	Any,
+	Type_Id,
+	Pointer,
+	Procedure,
+	Array,
+	Dynamic_Array,
+	Slice,
+	Tuple,
+	Struct,
+	Union,
+	Enum,
+	Map,
+	Bit_Field,
+	Bit_Set,
+	Opaque,
+	Simd_Vector,
+}
+
+
+type_kind :: proc(T: typeid) -> Type_Kind {
+	ti := type_info_of(T);
+	if ti != nil {
+		#complete switch _ in ti.variant {
+		case runtime.Type_Info_Named:         return .Named;
+		case runtime.Type_Info_Integer:       return .Integer;
+		case runtime.Type_Info_Rune:          return .Rune;
+		case runtime.Type_Info_Float:         return .Float;
+		case runtime.Type_Info_Complex:       return .Complex;
+		case runtime.Type_Info_String:        return .String;
+		case runtime.Type_Info_Boolean:       return .Boolean;
+		case runtime.Type_Info_Any:           return .Any;
+		case runtime.Type_Info_Type_Id:       return .Type_Id;
+		case runtime.Type_Info_Pointer:       return .Pointer;
+		case runtime.Type_Info_Procedure:     return .Procedure;
+		case runtime.Type_Info_Array:         return .Array;
+		case runtime.Type_Info_Dynamic_Array: return .Dynamic_Array;
+		case runtime.Type_Info_Slice:         return .Slice;
+		case runtime.Type_Info_Tuple:         return .Tuple;
+		case runtime.Type_Info_Struct:        return .Struct;
+		case runtime.Type_Info_Union:         return .Union;
+		case runtime.Type_Info_Enum:          return .Enum;
+		case runtime.Type_Info_Map:           return .Map;
+		case runtime.Type_Info_Bit_Field:     return .Bit_Field;
+		case runtime.Type_Info_Bit_Set:       return .Bit_Set;
+		case runtime.Type_Info_Opaque:        return .Opaque;
+		case runtime.Type_Info_Simd_Vector:   return .Simd_Vector;
+		}
+
+	}
+	return .Invalid;
+}
+
+// TODO(bill): Better name
+underlying_type_kind :: proc(T: typeid) -> Type_Kind {
+	return type_kind(runtime.typeid_base(T));
+}
+
+// TODO(bill): Better name
+backing_type_kind :: proc(T: typeid) -> Type_Kind {
+	return type_kind(runtime.typeid_core(T));
+}
+
+
+
+size_of_typeid :: proc(T: typeid) -> int {
+	if ti := type_info_of(T); ti != nil {
+		return ti.size;
+	}
+	return 0;
+}
+
+align_of_typeid :: proc(T: typeid) -> int {
+	if ti := type_info_of(T); ti != nil {
+		return ti.align;
+	}
+	return 1;
+}
+
+to_bytes :: proc(v: any) -> []byte {
+	if v != nil {
+		sz := size_of_typeid(v.id);
+		return mem.slice_ptr((^byte)(v.data), sz);
+	}
+	return nil;
+}
+
+any_data :: inline proc(v: any) -> (data: rawptr, id: typeid) {
+	return v.data, v.id;
+}
+
+is_nil :: proc(v: any) -> bool {
+	data := to_bytes(v);
+	if data != nil {
+		return true;
+	}
+	for v in data do if v != 0 {
+		return false;
+	}
+	return true;
+}
+
+
+index :: proc(v: any, i: int, loc := #caller_location) -> any {
+	if v == nil do return nil;
+
+	v := v;
+	v.id = runtime.typeid_base(v.id);
+	switch a in v {
+	case runtime.Type_Info_Array:
+		runtime.bounds_check_error_loc(loc, i, a.count);
+		offset := uintptr(a.elem.size * i);
+		data := rawptr(uintptr(v.data) + offset);
+		return any{data, a.elem.id};
+
+	case runtime.Type_Info_Slice:
+		raw := (^mem.Raw_Slice)(v.data);
+		runtime.bounds_check_error_loc(loc, i, raw.len);
+		offset := uintptr(a.elem.size * i);
+		data := rawptr(uintptr(raw.data) + offset);
+		return any{data, a.elem.id};
+
+	case runtime.Type_Info_Dynamic_Array:
+		raw := (^mem.Raw_Dynamic_Array)(v.data);
+		runtime.bounds_check_error_loc(loc, i, raw.len);
+		offset := uintptr(a.elem.size * i);
+		data := rawptr(uintptr(raw.data) + offset);
+		return any{data, a.elem.id};
+
+	case runtime.Type_Info_String:
+		if a.is_cstring do return nil;
+
+		raw := (^mem.Raw_String)(v.data);
+		runtime.bounds_check_error_loc(loc, i, raw.len);
+		offset := uintptr(size_of(u8) * i);
+		data := rawptr(uintptr(raw.data) + offset);
+		return any{data, typeid_of(u8)};
+	}
+	return nil;
+}
+
+
+
+
+Struct_Tag :: distinct string;
+
+Struct_Field :: struct {
+	name:   string,
+	type:   typeid,
+	tag:    Struct_Tag,
+	offset: uintptr,
+}
+
+struct_field_at :: proc(T: typeid, i: int) -> (field: Struct_Field) {
+	ti := runtime.type_info_base(type_info_of(T));
+	if s, ok := ti.variant.(runtime.Type_Info_Struct); ok {
+		if 0 <= i && i < len(s.names) {
+			field.name   = s.names[i];
+			field.type   = s.types[i].id;
+			field.tag    = Struct_Tag(s.tags[i]);
+			field.offset = s.offsets[i];
+		}
+	}
+	return;
+}
+
+struct_field_by_name :: proc(T: typeid, name: string) -> (field: Struct_Field) {
+	ti := runtime.type_info_base(type_info_of(T));
+	if s, ok := ti.variant.(runtime.Type_Info_Struct); ok {
+		for fname, i in s.names {
+			if fname == name {
+				field.name   = s.names[i];
+				field.type   = s.types[i].id;
+				field.tag    = Struct_Tag(s.tags[i]);
+				field.offset = s.offsets[i];
+				break;
+			}
+		}
+	}
+	return;
+}
+
+
+
+struct_field_names :: proc(T: typeid) -> []string {
+	ti := runtime.type_info_base(type_info_of(T));
+	if s, ok := ti.variant.(runtime.Type_Info_Struct); ok {
+		return s.names;
+	}
+	return nil;
+}
+
+struct_field_types :: proc(T: typeid) -> []^runtime.Type_Info {
+	ti := runtime.type_info_base(type_info_of(T));
+	if s, ok := ti.variant.(runtime.Type_Info_Struct); ok {
+		return s.types;
+	}
+	return nil;
+}
+
+
+struct_field_tags :: proc(T: typeid) -> []Struct_Tag {
+	ti := runtime.type_info_base(type_info_of(T));
+	if s, ok := ti.variant.(runtime.Type_Info_Struct); ok {
+		return transmute([]Struct_Tag)s.tags;
+	}
+	return nil;
+}
+
+struct_field_offsets :: proc(T: typeid) -> []uintptr {
+	ti := runtime.type_info_base(type_info_of(T));
+	if s, ok := ti.variant.(runtime.Type_Info_Struct); ok {
+		return s.offsets;
+	}
+	return nil;
+}
+
+
+
+struct_tag_get :: proc(tag: Struct_Tag, key: string) -> (value: string) {
+	value, _ = struct_tag_lookup(tag, key);
+	return;
+}
+
+struct_tag_lookup :: proc(tag: Struct_Tag, key: string) -> (value: string, ok: bool) {
+	for tag := tag; tag != ""; /**/ {
+		i := 0;
+		for i < len(tag) && tag[i] == ' ' { // Skip whitespace
+			i += 1;
+		}
+		tag = tag[i:];
+		if len(tag) == 0 do break;
+
+		i = 0;
+		loop: for i < len(tag) {
+			switch tag[i] {
+			case ':', '"':
+				break loop;
+			case 0x00 ..< ' ', 0x7f .. 0x9f: // break if control character is found
+				break loop;
+			}
+			i += 1;
+		}
+
+		if i == 0 do break;
+		if i+1 >= len(tag) do break;
+
+		if tag[i] != ':' || tag[i+1] != '"' {
+			break;
+		}
+		name := string(tag[:i]);
+		tag = tag[i+1:];
+
+		i = 1;
+		for i < len(tag) && tag[i] != '"' { // find closing quote
+			if tag[i] == '\\' do i += 1; // Skip escaped characters
+			i += 1;
+		}
+
+		if i >= len(tag) do break;
+
+		val := string(tag[:i+1]);
+		tag = tag[i+1:];
+
+		if key == name {
+			return val[1:i], true;
+		}
+	}
+	return;
+}
diff --git a/core/runtime/core.odin b/core/runtime/core.odin
index 28767cc2d..047281b10 100644
--- a/core/runtime/core.odin
+++ b/core/runtime/core.odin
@@ -283,19 +283,21 @@ type_info_base :: proc "contextless" (info: ^Type_Info) -> ^Type_Info {
 }
 
 
-type_info_base_without_enum :: proc "contextless" (info: ^Type_Info) -> ^Type_Info {
+type_info_core :: proc "contextless" (info: ^Type_Info) -> ^Type_Info {
 	if info == nil do return nil;
 
 	base := info;
 	loop: for {
 		switch i in base.variant {
-		case Type_Info_Named: base = i.base;
-		case Type_Info_Enum:  base = i.base;
+		case Type_Info_Named:  base = i.base;
+		case Type_Info_Enum:   base = i.base;
+		case Type_Info_Opaque: base = i.elem;
 		case: break loop;
 		}
 	}
 	return base;
 }
+type_info_base_without_enum :: type_info_core;
 
 __type_info_of :: proc "contextless" (id: typeid) -> ^Type_Info {
 	data := transmute(Typeid_Bit_Field)id;
@@ -311,10 +313,11 @@ typeid_base :: proc "contextless" (id: typeid) -> typeid {
 	ti = type_info_base(ti);
 	return ti.id;
 }
-typeid_base_without_enum :: proc "contextless" (id: typeid) -> typeid {
+typeid_core :: proc "contextless" (id: typeid) -> typeid {
 	ti := type_info_base_without_enum(type_info_of(id));
 	return ti.id;
 }
+typeid_base_without_enum :: typeid_core;
 
 
 
diff --git a/examples/demo/demo.odin b/examples/demo/demo.odin
index e07eea7c7..157ecb9bf 100644
--- a/examples/demo/demo.odin
+++ b/examples/demo/demo.odin
@@ -4,6 +4,7 @@ import "core:fmt"
 import "core:mem"
 import "core:os"
 import "core:runtime"
+import "core:reflect"
 
 when os.OS == "windows" {
 	import "core:thread"
@@ -946,26 +947,39 @@ deferred_procedure_associations :: proc() {
 	}
 }
 
-struct_field_tags :: proc() {
-	fmt.println("# struct_field_tags");
+reflection :: proc() {
+	fmt.println("# reflection");
 
 	Foo :: struct {
 		x: int    `tag1`,
-		y: string `tag2`,
+		y: string `json:"y_field"`,
 		z: bool, // no tag
 	}
 
-	ti := runtime.type_info_base(type_info_of(Foo));
-	s := ti.variant.(runtime.Type_Info_Struct);
+	id := typeid_of(Foo);
+	names := reflect.struct_field_names(id);
+	types := reflect.struct_field_types(id);
+	tags  := reflect.struct_field_tags(id);
+
+	assert(len(names) == len(types) && len(names) == len(tags));
+
 	fmt.println("Foo :: struct {");
-	for _, i in s.names {
-		if tag := s.tags[i]; tag != "" {
-			fmt.printf("\t%s: %T `%s`,\n", s.names[i], s.types[i], tag);
+	for tag, i in tags {
+		name, type := names[i], types[i];
+		if tag != "" {
+			fmt.printf("\t%s: %T `%s`,\n", name, type, tag);
 		} else {
-			fmt.printf("\t%s: %T,\n", s.names[i], s.types[i]);
+			fmt.printf("\t%s: %T,\n", name, type);
 		}
 	}
 	fmt.println("}");
+
+
+	for tag, i in tags {
+		if val, ok := reflect.struct_tag_lookup(tag, "json"); ok {
+			fmt.printf("json: %s -> %s\n", names[i], val);
+		}
+	}
 }
 
 main :: proc() {
@@ -986,6 +1000,6 @@ main :: proc() {
 		bit_set_type();
 		diverging_procedures();
 		deferred_procedure_associations();
-		struct_field_tags();
+		reflection();
 	}
 }
diff --git a/src/check_decl.cpp b/src/check_decl.cpp
index f3e0f70bc..cf3cb8e97 100644
--- a/src/check_decl.cpp
+++ b/src/check_decl.cpp
@@ -1074,6 +1074,11 @@ void check_entity_decl(CheckerContext *ctx, Entity *e, DeclInfo *d, Type *named_
 }
 
 
+struct ProcUsingVar {
+	Entity *e;
+	Entity *uvar;
+};
+
 
 void check_proc_body(CheckerContext *ctx_, Token token, DeclInfo *decl, Type *type, Ast *body) {
 	if (body == nullptr) {
@@ -1098,58 +1103,85 @@ void check_proc_body(CheckerContext *ctx_, Token token, DeclInfo *decl, Type *ty
 	ctx->curr_proc_decl = decl;
 	ctx->curr_proc_sig  = type;
 
-	GB_ASSERT(type->kind == Type_Proc);
-	if (type->Proc.param_count > 0) {
-		TypeTuple *params = &type->Proc.params->Tuple;
-		for_array(i, params->variables) {
-			Entity *e = params->variables[i];
-			if (e->kind != Entity_Variable) {
-				continue;
-			}
-			if (!(e->flags & EntityFlag_Using)) {
-				continue;
-			}
-			bool is_immutable = e->Variable.is_immutable;
-			bool is_value     = (e->flags & EntityFlag_Value) != 0 && !is_type_pointer(e->type);
-			String name = e->token.string;
-			Type *t = base_type(type_deref(e->type));
-			if (t->kind == Type_Struct) {
-				Scope *scope = t->Struct.scope;
-				if (scope == nullptr) {
-					scope = scope_of_node(t->Struct.node);
+	ast_node(bs, BlockStmt, body);
+
+	Array<ProcUsingVar> using_entities = {};
+	using_entities.allocator = heap_allocator();
+	defer (array_free(&using_entities));
+
+	{
+		GB_ASSERT(type->kind == Type_Proc);
+		if (type->Proc.param_count > 0) {
+			TypeTuple *params = &type->Proc.params->Tuple;
+			for_array(i, params->variables) {
+				Entity *e = params->variables[i];
+				if (e->kind != Entity_Variable) {
+					continue;
 				}
-				GB_ASSERT(scope != nullptr);
-				for_array(i, scope->elements.entries) {
-					Entity *f = scope->elements.entries[i].value;
-					if (f->kind == Entity_Variable) {
-						Entity *uvar = alloc_entity_using_variable(e, f->token, f->type);
-						uvar->Variable.is_immutable = is_immutable;
-						if (is_value) uvar->flags |= EntityFlag_Value;
-
-						Entity *prev = scope_insert(ctx->scope, uvar);
-						if (prev != nullptr) {
-							error(e->token, "Namespace collision while 'using' '%.*s' of: %.*s", LIT(name), LIT(prev->token.string));
-							break;
+				if (!(e->flags & EntityFlag_Using)) {
+					continue;
+				}
+				bool is_immutable = e->Variable.is_immutable;
+				bool is_value     = (e->flags & EntityFlag_Value) != 0 && !is_type_pointer(e->type);
+				String name = e->token.string;
+				Type *t = base_type(type_deref(e->type));
+				if (t->kind == Type_Struct) {
+					Scope *scope = t->Struct.scope;
+					if (scope == nullptr) {
+						scope = scope_of_node(t->Struct.node);
+					}
+					GB_ASSERT(scope != nullptr);
+					for_array(i, scope->elements.entries) {
+						Entity *f = scope->elements.entries[i].value;
+						if (f->kind == Entity_Variable) {
+							Entity *uvar = alloc_entity_using_variable(e, f->token, f->type);
+							uvar->Variable.is_immutable = is_immutable;
+							if (is_value) uvar->flags |= EntityFlag_Value;
+
+
+							ProcUsingVar puv = {e, uvar};
+							array_add(&using_entities, puv);
+
 						}
 					}
+				} else {
+					error(e->token, "'using' can only be applied to variables of type struct");
+					break;
 				}
-			} else {
-				error(e->token, "'using' can only be applied to variables of type struct");
-				break;
 			}
 		}
 	}
 
-	ast_node(bs, BlockStmt, body);
+
+	for_array(i, using_entities) {
+		Entity *e = using_entities[i].e;
+		Entity *uvar = using_entities[i].uvar;
+		Entity *prev = scope_insert(ctx->scope, uvar);
+		if (prev != nullptr) {
+			error(e->token, "Namespace collision while 'using' '%.*s' of: %.*s", LIT(e->token.string), LIT(prev->token.string));
+			break;
+		}
+	}
+
 	check_open_scope(ctx, body);
-	check_stmt_list(ctx, bs->stmts, Stmt_CheckScopeDecls);
-	if (type->Proc.result_count > 0) {
-		if (!check_is_terminating(body)) {
-			if (token.kind == Token_Ident) {
-				error(bs->close, "Missing return statement at the end of the procedure '%.*s'", LIT(token.string));
-			} else {
-				// NOTE(bill): Anonymous procedure (lambda)
-				error(bs->close, "Missing return statement at the end of the procedure");
+	{
+		for_array(i, using_entities) {
+			Entity *e = using_entities[i].e;
+			Entity *uvar = using_entities[i].uvar;
+			Entity *prev = scope_insert(ctx->scope, uvar);
+			// NOTE(bill): Don't err here
+		}
+
+		check_stmt_list(ctx, bs->stmts, Stmt_CheckScopeDecls);
+
+		if (type->Proc.result_count > 0) {
+			if (!check_is_terminating(body)) {
+				if (token.kind == Token_Ident) {
+					error(bs->close, "Missing return statement at the end of the procedure '%.*s'", LIT(token.string));
+				} else {
+					// NOTE(bill): Anonymous procedure (lambda)
+					error(bs->close, "Missing return statement at the end of the procedure");
+				}
 			}
 		}
 	}
diff --git a/src/check_expr.cpp b/src/check_expr.cpp
index 99fe6695b..7a6e0f22d 100644
--- a/src/check_expr.cpp
+++ b/src/check_expr.cpp
@@ -7164,7 +7164,7 @@ ExprKind check_expr_base_internal(CheckerContext *c, Operand *o, Ast *node, Type
 				if (o->mode == Addressing_Constant) {
 					max_count = o->value.value_string.len;
 				}
-				o->type = t_string;
+				o->type = type_deref(o->type);
 			}
 			break;