GrammarType

class ase2sprkkr.common.grammar_types.GrammarType(prefix=None, postfix=None, format='', default_value=None, condition=None, after_convert=None, description='')

Base class for definition of configuration option types

A type without value (e.g. Separator) are just syntactical elements in the potentials file, that do not carry an information. Such elements do not yields (name, value) pair during parsing the file.

Do not confuse this with GrammarType.missing_value functionality. Missing_value is just the opposite: missing_value can be ommited in the file (or even the absence of the name in the file carry the information, that the Flag is False), but the name-value tuple of such Type is present in the parse result. On the other hand, has_value = False is in the file, but not in the result.

The functions called during…

User input:  convert, validate

Output: string -> _string

Parsing: parse -> ( <_grammar parse actions>, validate(why='parse') )

Class hierarchy

Constructor

Parameters

• prefix (Optional[str]) –

• postfix (Optional[str]) –

• format (str) –

• default_value (Any) –

• condition (Optional[Callable[[Any], Union[bool, str]]]) –

• after_convert (Optional[Callable[[Any], Any]]) –

__init__(prefix=None, postfix=None, format='', default_value=None, condition=None, after_convert=None, description='')

Create the object.

Parameters

• prefix (Optional[str]) – The string, that will be printed before the value

• postfix (Optional[str]) – The string, that will be printed after the value

• format (str) – The (python) format string, that will be used for printing the value. The format is passed as format argument to str.format routine.

• default_value (Optional[Any]) – The default value of the options of this type. None means no default value.

• condition (Optional[Callable[[Any], Union[bool, str]]]) – Function, that check the validity of the value. It should return True for a valid value, and False or string for invalid. The string is interpreted as an error message that explains the invalidity of the value.

• after_convert (Optional[Callable[[Any], Any]]) – Function, that - if it is given - is applied to the (entered or parsed) value. The function is applied on the result of the convert method

has_value = True

name_in_grammar = True

Default value for ValueDefinition.name_in_grammar. Some types (e.g. Tables) commonly have no name (are identified by its position in the potential file) – such type could redefine this class property.

numpy_type

The numpy dtype of the array, that contains values of this type (see e.g. Array). The default type object can and should be redefined in the descendatns.

alias of object

prefix

The string, that will be printed before the value

postfix

The string, that will be printed after the value

format

The (python) format string, that will be used for printing the value. The format is passed as format argument to str.format routine.

default_value = None

Default value for the given type. It can be overriden for particular instances in the constructor (or just by setting the attribute of an instantiated object).

static is_the_same_value(a, b)

Comparison function for the values of “this type”.

Not all values (e.g. numpy arrays) can be compared by equal sign, so this function has to be used for comparison of the values.

grammar(param_name=False)

Return a pyparsing grammar for the type

Parameters

param_name (str) – The name of the value, that can be assigned to the generated grammar element.

parse(str, whole_string=True)

Parse the string, return the obtained value.

async parse_from_stream(stream, up_to, start=None, whole_string=True)

grammar_name()

Human readable expression of the grammar. By default, this is what is set by grammar.setName, however, sometimes is desirable to set even shorter string

transform_grammar(grammar, param_name=False)

The chance for the resulting class to alter the resulting prefixed grammar

missing_value()

Is the configuraion value a flag? I.e., can be =<value> ommited in the configuration?

Returns

• can_be_ommited (bool) – Is an ommision of the value possible, e.g. the option is given as Flag (only by name of the option)

• default_value – The value used if the value is ommitted

• do_not_output_the_option – The value, for which the variable should not be outputed at all (e.g. False for a flag)

validate(value, param_name='<Unknown>', why='set')

Validate either the pyparsing result or a user given value.

Do not override this method in subclasses for the validation implementation, this method calls _validate(), which should contain the actual validation

Parameters

• value (mixed) – Value to be validated.

• param_name (str or callable) – Parameter name to be used in possible throwed exception (Optional). If it is callable, it should be a function that returns the param_name.

• why (str) –

  Possible values are:

  set

  validation value setted by user (in rare cases, such value can be incomplete and requires completing during set_from_atoms call before saving the output)

  parse

  validation during parsing input file, checks enforced by the grammar can be skipped

  save

  validation before saving the values

_validate(value, why='set')

Return error message if the value is not valid.

_valueError(value, error_message=False, param_name=False)

read(token, parameterName='<Unknown>')

Transform pyparsing token to a validated value

convert(value)

Convert a value from user to the “cannonical form”

_string(val)

The string method do some additional transformation (add prefix, postfix etc.), so the actual way how to convert the value for the output should be here.

string(val)

Convert the value to the string according to the class definition. Do not redefine this function, redefine the _string() method instead, to retain the common functionality (as adding prefix or postfix to the resulting string).

write(f, val)

Output the value to the stream (in the propper format).

print(val)

Output the value to stdout (in the propper format).

copy()

enrich(option)

Some types can add properties to the options that have the type, e.g. see Sequence.enrich, which adds the ability to access the items of the sequence using []

additional_description(prefix='')

If the description of the type does not fit on one line, this method should return

Returns

The additional description (e.g. possible choices) of the type. Multiline string.

Return type

additional_description

type_validation(value, types, typename=None)

Parameters

• value (mixed) – Value to be checked

• types (Union[List[Type], Type]) – The required type or types. If more types is given, it is sufficient, if the value is of any of given types.

• typename (Optional[str]) –

Returns

error_message – The function returns either False, if the value is ok, or string containing an error message describing the error.

Return type

Union[str, bool]