knit_script.knit_script_interpreter.expressions.direction module

Accesses machine directions.

This module provides the Pass_Direction_Expression class, which handles the parsing and evaluation of carriage pass direction expressions in knit script code. It supports various direction keywords and contextual direction references, converting them into the appropriate Carriage_Pass_Direction objects.

class Pass_Direction_Expression(parser_node, dir_word)

Bases: Expression

Expression of a Machine Pass Direction.

The Pass_Direction_Expression class handles the conversion of direction keywords in knit script source code into Carriage_Pass_Direction objects. It supports both explicit direction keywords (like “Leftward”, “Rightward”) and contextual references (like “current”, “reverse”) that depend on the current machine state.

This expression type is essential for carriage pass operations where the direction of needle processing must be specified. It provides flexibility in how directions are specified while ensuring they resolve to the correct machine direction values.

_dir_word

The direction keyword from the source code.

Type:

str

__init__(parser_node, dir_word)

Initialize the Pass_Direction_Expression.

Parameters:

• parser_node (LRStackNode) – The parser node from the parse tree.

• dir_word (str) – Keyword for the direction, such as “Leftward”, “Rightward”, “current”, or “reverse”.

evaluate(context)

Evaluate the expression to get the corresponding carriage pass direction.

Converts the direction keyword into the appropriate Carriage_Pass_Direction object, handling both explicit directions and contextual references that depend on the current machine state.

Parameters:

context (Knit_Script_Context) – The current context of the knit_script_interpreter.

Returns:

The carriage pass direction corresponding to the keyword.

Return type:

Carriage_Pass_Direction

Note

Supported keywords: - “Leftward”, “Decreasing”: Returns leftward direction - “Rightward”, “Increasing”: Returns rightward direction - “current”: Returns the current direction from context - “reverse”: Returns the opposite of the current direction

classmethod __class_getitem__(params)

Parameterizes a generic class.

At least, parameterizing a generic class is the main thing this method does. For example, for some generic class Foo, this is called when we do Foo[int] - there, with cls=Foo and params=int.

However, note that this method is also called when defining generic classes in the first place with class Foo(Generic[T]): ….

classmethod __init_subclass__(**kwargs)

Automatically wrap evaluate methods in subclasses with appropriate error handling decorator.

This method is called whenever a class inherits from Expression. It checks if the subclass defines its own evaluate method and wraps it with the appropriate decorator.

Parameters:

**kwargs (Any) – Additional keyword arguments passed to super().__init_subclass__

property file_name: str | None

Returns: str | None: The file name of the knitscript program this was parsed from or None if the program was passed as a string.

property line_number: int

Get the line number of the symbol that generated this statement.

Returns:

The line number where this element appears in the source file.

Return type:

int

property local_path: str | None

Returns: str | None: The path to the directory containing the file from which this element was parsed or None if the value was parsed from a python string.

property location: Location

Get the location of this symbol in KnitScript file.

Returns:

The location of this symbol in the source file, including file name, line number, and position information.

Return type:

Location

property location_str: str

Returns: str: The string referencing the line number and possible file name information about this element.

property position_context: str

The position context string is the string from the knitscript program from which this element was parsed. The context string will begin at the start of this element and continue to the end of the line of knitscript or a semicolon on new line are reached.

Returns:

The string used to contextualize this element in the knitscript program.

Return type:

str