A lightweight, optionally typed expression language with a custom grammar for matching arbitrary Python objects.
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A lightweight, optionally typed expression language with a custom grammar for matching arbitrary Python objects.
Documentation is available at https://zeroSteiner.github.io/rule-engine/.
Rule Engine expressions are written in their own language, defined as strings in Python. The syntax is most similar to Python with some inspiration from Ruby. Some features of this language includes:
The following example demonstrates the basic usage of defining a rule object and applying it to two dictionaries,
showing that one matches while the other does not. See Getting Started
_ for more information.
.. code-block:: python
import rule_engine
rule = rule_engine.Rule(
'first_name == "Luke" and email =~ ".*@rebels.org$"'
) # =>
The next example demonstrates the optional type system. A custom context is created that defines two symbols, one string
and one float. Because symbols are defined, an exception will be raised if an unknown symbol is specified or an invalid
operation is used. See Type Hinting
_ for more information.
.. code-block:: python
import rule_engine
context = rule_engine.Context(type_resolver=rule_engine.type_resolver_from_dict({ 'first_name': rule_engine.DataType.STRING, 'age': rule_engine.DataType.FLOAT }))
rule = rule_engine.Rule('last_name == "Vader"', context=context)
rule = rule_engine.Rule('first_name + 1', context=context)
Want to give the rule expression language a try? Checkout the Debug REPL
_ that makes experimentation easy. After
installing just run python -m rule_engine.debug_repl
.
Install the latest release from PyPi using pip install rule-engine
. Releases follow Semantic Versioning
_ to
indicate in each new version whether it fixes bugs, adds features or breaks backwards compatibility. See the
Change Log
_ for a curated list of changes.
The Rule Engine library is released under the BSD 3-Clause license. It is able to be used for both commercial and
private purposes. For more information, see the LICENSE
_ file.
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.. _Change Log: https://zerosteiner.github.io/rule-engine/change_log.html .. _Debug REPL: https://zerosteiner.github.io/rule-engine/debug_repl.html .. _Getting Started: https://zerosteiner.github.io/rule-engine/getting_started.html .. _LICENSE: https://github.com/zeroSteiner/rule-engine/blob/master/LICENSE .. _Semantic Versioning: https://semver.org/ .. _Type Hinting: https://zerosteiner.github.io/rule-engine/getting_started.html#type-hinting