textfsm for Acton

TextFSM-compatible template parser for Acton, focused on:

• 100% compatibility with TextFSM templates
• Type-safe, ergonomic Acton interface
  • Usage varies from the Python version

Quick start

from textfsm import parse_textfsm, compile_textfsm

def main():
    template = r"""Value IFACE (\S+)
Value STATUS (up|down)

Start
  ^${IFACE}\s+${STATUS} -> Record
"""
    rows = parse_textfsm(template, "ge0 up\nge1 down\n")
    for row in rows:
        print(row.get("IFACE"), row.get("STATUS"))

    compiled = compile_textfsm(template)
    rows2 = compiled.parse("ge2 up\n")
    print(rows2[0].get("IFACE"))

Public API

• parse_textfsm(template: str, text: str, eof: bool=True) -> list[Row]
• compile_textfsm(template: str) -> CompiledTemplate
• CompiledTemplate.parse(text: str, eof: bool=True) -> list[Row]
• CompiledTemplate.schema() -> list[FieldSchema]
• Row.get(field: str) -> ?str
• Row.get_def(field: str, default: str) -> str
• Row.many(field: str) -> list[str]
• Row.many_records(field: str) -> list[dict[str, str]] (for nested named groups in Value List)
• Row.to_dict() -> dict[str, list[str]]

Row.get() returns None when a field has no capture. A field that captures an empty string returns "".

CompiledTemplate.schema() returns one FieldSchema per Value, in template order. FieldSchema.is_list is True for Value List values and False for normal values. FieldSchema.record_fields contains nested named capture groups for Value List, which are exposed on parsed rows through Row.many_records().

Exceptions

• Error
• UsageError
• TextFSMError (runtime parse errors, e.g. -> Error)
• TextFSMTemplateError (template syntax/semantic errors)

TextFSM compatibility

Supported parser/runtime semantics include:

• Value options: Required, Filldown, Fillup, List
• Rule actions: Next, Continue, Error, Record, NoRecord, Clear, Clearall
• State transitions including Start, End, EOF
• Implicit EOF record behavior and eof=False suppression
• Variable substitution forms: $name, ${name}, $$
• Nested named capture groups for Value List (exposed via Row.many_records())

Intentionally not implemented:

• Value Key
• clitable

Notes on templates in Acton strings

Acton strings interpolate by default. Use raw strings for templates:

template = r"""..."""

This avoids escaping issues around $name, ${name}, and regex backslashes.

License and attribution

This project is licensed under Apache License 2.0; see LICENSE.

The parser behavior and parts of the test corpus are derived from upstream Python TextFSM:

• https://github.com/google/textfsm

Upstream TextFSM is also licensed under Apache License 2.0.