如何在文本语法的有序选择表达式中使用 link 规则引用？

Question

我是 TextX 新手。我正在尝试创建一个语法来定义数据类型，这些数据类型的字段可以是简单类型或其他数据类型的类型。语法说明为：

Library: 
    data_types *= DataType
;

DataType: name=ID "{" 
fields*=Field
"}" ;

Field: type=([DataType] | ID) name=ID;
//Type: [DataType] | ID;

遵循此语法的模型示例是

vec { 
int64 a
int64 b
int64 c
}

matrix {
    vec a
    vec b
}

我想 link 将字段的类型设置为已声明的数据类型或一些简单的字符串。但是，当用 textx generate dummy.tx --target dot 编译上述语法时，我得到错误 Error: None:9:13: error: Expected ''((\')|[^'])*'' or '"((\")|[^"])*"' or re_match or rule_ref or '[' at position dummy.tx:(9, 13) => 'eld: type=*([DataType'..

有什么方法可以实现我想要的吗？我曾尝试将类型声明放在一个单独的块中，如评论中所示，但这没有帮助。任何建议或提示将不胜感激。

Answer 1

标准方法是使用自定义类并为所有非用户自己创建的类型创建内置函数。最好使用您的示例在代码中展示它是如何完成的。请注意 registration so that the language with registered builtins can be available to textx CLI command. Also, see the entity example 的使用，因为那里使用了相同的技术。

from textx import metamodel_from_str
from textx.registration import (language, register_language,
                                metamodel_for_language)

# We use registration support to register language
# This way it will be available to textx CLI command
@language('library', '.lib')
def library_lang():
    "Library language."

    grammar = r'''
    Library:
        data_types *= DataType
    ;

    DataType: name=ID "{"
        fields*=Field
    "}" ;

    Field: type=[Type] name=ID;
    Type: DataType | BuiltInType;
    BuiltInType: name=ID;
    '''

    # Here we use our class for builtin types so we can
    # make our own instances for builtin types.
    # See textX Entity example for more.
    class BuiltInType:
        def __init__(self, parent, name):
            self.parent = parent
            self.name = name

    # Create all builtin instances.
    builtins = {
        'int64': BuiltInType(None, 'int64'),
    }

    return metamodel_from_str(grammar,
                              # Register custom classes and builtins.
                              classes=[BuiltInType],
                              builtins=builtins)


# This should really be done through setup.{cfg,py}
# Here it is done through registration API for an example to
# be self-contained.
register_language(library_lang)

model_str = r'''
vec {
int64 a
int64 b
int64 c
}

matrix {
    vec a
    vec b
}

'''

# Now we can get registered language metamodel by name and
# parse our model.
model = metamodel_for_language('library').model_from_str(model_str)
# ... do something with the model
assert len(model.data_types) == 2
assert model.data_types[0].name == 'vec'
assert model.data_types[0].fields[0].name == 'a'
assert model.data_types[0].fields[0].type.name == 'int64'

如何在文本语法的有序选择表达式中使用 link 规则引用？

How to use a link rule reference in an ordered choice expression in a TextX grammar?

textx