nomsu/lib/object.nom

use "core"

compile [@%var] to:
    lua> ".."
        local key_lua = repr(\%var.value);
        local key_attr = (key_lua:match("'([a-zA-Z][a-zA-Z0-9]*)'")
                       or key_lua:match('"([a-zA-Z][a-zA-Z0-9]*)"'));
        if key_attr then
            return {expr="_me."..key_attr};
        elseif key_lua:sub(1,1) == "[" then
            key_lua = " "..key_lua.." ";
        end
        return {expr="_me["..key_lua.."]"};

compile [@%var <- %val] to:
    lua> ".."
        local val_lua = \(%val as lua expr);
        local key_lua = repr(\%var.value);
        local key_attr = (key_lua:match("'([a-zA-Z][a-zA-Z0-9]*)'")
                       or key_lua:match('"([a-zA-Z][a-zA-Z0-9]*)"'));
        if key_attr then
            return {statements="_me."..key_attr.." = "..val_lua..";"};
        elseif key_lua:sub(1,1) == "[" then
            key_lua = " "..key_lua.." ";
        end
        return {statements="_me["..key_lua.."] = "..val_lua..";"};

compile [define object %classname %class_body] to:
    %class_identifier <- (=lua "nomsu:var_to_lua_identifier(\(%classname as value)):sub(2,-1)")
    if: %class_identifier is ""
        %class_identifier <- "class"
    %methods <- []
    for %line in (%class_body's "value"):
        if: (%line's "type") is "Comment"
            do next %line
        assume (((%line's "type") == "FunctionCall") and ((%line's stub) == "action % %"))
        ..or barf "Only action definitions are supported inside 'define object % %', not \(%line's "src")"
        %actions <- (2nd in (%line's "value"))
        %body <- (3rd in (%line's "value"))
        lua> ".."
            local stubs = {};
            for i, action in ipairs(\%actions.value) do
                stubs[i] = nomsu:tree_to_named_stub(action);
            end
            local args = {};
            for i,tok in ipairs(\%actions.value[1].value) do
                if tok.type == "Var" then args[#args+1] = nomsu:var_to_lua_identifier(tok.value); end
            end
            local arg_set = {};
            for i, arg in ipairs(args) do arg_set[arg] = true; end
            local body_lua = nomsu:tree_to_lua(\%body);
            local body_code = body_lua.statements or ("return "..body_lua.expr..";");
            local undeclared_locals = {};
            for i, body_local in ipairs(body_lua.locals or {}) do
                if not arg_set[body_local] then
                    table.insert(undeclared_locals, body_local);
                end
            end
            if #undeclared_locals > 0 then
                body_code = "local "..table.concat(undeclared_locals, ", ")..";\\n"..body_code;
            end
            local lua_fn_args = table.concat(args, ", ");
            local def_tree = nomsu.compilestack[#nomsu.compilestack];
            local code_location = ("%s:%s,%s"):format(def_tree.filename, def_tree.start, def_tree.stop);

            local compiled_args = {};
            for i, arg in ipairs(args) do
                compiled_args[i] = "nomsu:tree_to_lua("..arg..").expr";
            end
            compiled_args = table.concat(compiled_args, "..', '..");
            table.insert(\%methods, ([==[
                %s[ %s] = function(%s)
                    %s
                end
                nomsu:define_compile_action(%s, %s, function(%s)
                    return {expr="("..nomsu:tree_to_lua(_me).expr..")[ "..%s.."]("..%s..")"};
                end);
                ACTION_METADATA[%s[ %s]] = ACTION_METADATA[ACTION[ %s]];
            ]==]):format(
                \%class_identifier, repr(stubs[1]), lua_fn_args,
                    body_code,
                repr(stubs), repr(code_location), lua_fn_args,
                    repr(repr(stubs[1])), compiled_args,
                \%class_identifier, repr(stubs[1]), repr(stubs[1])));

    return {..}
        statements:".."
            do -- \%class_identifier
                -- Create the class object:
                local \%class_identifier = setmetatable({
                    name=\(%classname as lua expr), instances=setmetatable({}, {__mode="k"}),
                }, {
                    __tostring=function(c) return c.name; end,
                    __call=function(cls, inst)
                        inst = inst or {};
                        inst.id = tostring(inst):match('table: (.*)');
                        setmetatable(inst, cls.instance_metatable);
                        cls.instances[inst] = true;
                        if inst['set % up'] then
                            inst['set % up'](inst);
                        end
                        return inst;
                    end,
                });
                \%class_identifier.class = \%class_identifier;

                -- Define the methods:
            \(%methods joined with "\n")

                -- Define class methods for instantiating and accessing instances:
                \%class_identifier.instance_metatable = {
                    __index=\%class_identifier,
                    __tostring=\%class_identifier['% as text'] or function(inst)
                        return "<"..inst.class.name..": "..inst.id..">";
                    end,
                };
                nomsu:define_action("instances of "..\%class_identifier.name, "lib/class.nom", function()
                    return utils.keys(\%class_identifier.instances);
                end, "");
                nomsu:define_action("new "..\%class_identifier.name.." %instance", "lib/class.nom", function(_instance)
                    return \%class_identifier(_instance);
                end, "");
                nomsu:define_action("new "..\%class_identifier.name, "lib/class.nom", function()
                    return \%class_identifier({});
                end, "");
            end -- End of definition of \%class_identifier
            \("\n\n")