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Package ruler
Short Description The Hoa\Ruler library.
License BSD-3-Clause
Homepage https://hoa-project.net/
Informations about the package ruler
Hoa is a modular, extensible and
structured set of PHP libraries.
Moreover, Hoa aims at being a bridge between industrial and research worlds.
Hoa\Ruler
This library allows to manipulate a rule engine. Rules can be written by using a dedicated language, very close to SQL. Therefore, they can be written by a user and saved in a database.
Such rules are useful, for example, for commercial solutions that need to manipulate promotion or special offer rules written by a user. To quote Wikipedia:
A business rules engine is a software system that executes one or more business rules in a runtime production environment. The rules might come from legal regulation (“An employee can be fired for any reason or no reason but not for an illegal reason”), company policy (“All customers that spend more than $100 at one time will receive a 10% discount”), or other sources. A business rule system enables these company policies and other operational decisions to be defined, tested, executed and maintained separately from application code.
Installation
With Composer, to include this library into
your dependencies, you need to
require hoa/ruler
:
For more installation procedures, please read the Source page.
Testing
Before running the test suites, the development dependencies must be installed:
Then, to run all the test suites:
For more information, please read the contributor guide.
Quick usage
As a quick overview, we propose to see a very simple example that manipulates a simple rule with a simple context. After, we will add a new operator in the rule. And finally, we will see how to save a rule in a database.
Three steps
So first, we create a context with two variables: group
and points
, and we
then assert a rule. A context holds values to concretize a rule. A value can
also be the result of a callable. Thus:
In the next example, we have a User
object and a context that is populated
dynamically (when the user
variable is concretized, two new variables, group
and points
are created). Moreover, we will create a new operator/function
called logged
. There is no difference between an operator and a function
except that an operator has two operands (so arguments).
Adding operators and functions
For now, we have the following operators/functions by default: and
, or
,
xor
, not
, =
(is
as an alias), !=
, >
, >=
, <
, <=
, in
and
sum
. We can add our own by different way. The simplest and volatile one is
given in the following example. Thus:
Also, if a variable in the context is an array, we can access to its values from
a rule with the same syntax as PHP. For example, if the a
variable is an
array, we can write a[0]
to access to the value associated to the 0
key. It
works as an hashmap (PHP array implementation), so we can have strings & co. as
keys. In the same way, if a variable is an object, we can call a method on it.
For example, if the a
variable is an array where the value associated to the
first key is an object with a foo
method, we can write: a[0].foo(b)
where
b
is another variable in the context. Also, we can access to the public
attributes of an object. Obviously, we can mixe array and object accesses.
Please, take a look at the grammar (hoa://Library/Ruler/Grammar.pp
) to see all
the possible constructions.
Saving a rule
Now, we have two options to save the rule, for example, in a database. Either we
save the rule as a string directly, or we will save the serialization of the
rule which will avoid further interpretations. In the next example, we see how
to serialize and unserialize a rule by using the Hoa\Ruler\Ruler::interpret
static method:
And for next executions:
When a rule is interpreted, its object model is created. We serialize and unserialize this model. To see the PHP code needed to create such a model, we can print the model itself (as an example). Thus:
Have fun!
Documentation
The
hack book of Hoa\Ruler
contains
detailed information about how to use this library and how it works.
To generate the documentation locally, execute the following commands:
More documentation can be found on the project's website: hoa-project.net.
Getting help
There are mainly two ways to get help:
- On the
#hoaproject
IRC channel, - On the forum at users.hoa-project.net.
Contribution
Do you want to contribute? Thanks! A detailed contributor guide explains everything you need to know.
License
Hoa is under the New BSD License (BSD-3-Clause). Please, see
LICENSE
for details.
Related projects
The following projects are using this library:
- RulerZ, Powerful implementation of the Specification pattern in PHP,
- ownCloud, A safe home for all your data,
- PhpMetrics, Static analysis tool for PHP,
hiqdev/php-billing
, a billing library in PHPatoum/ruler-extension
, This extension allows to filter test results in atoum.
All versions of ruler with dependencies
hoa/consistency Version ~1.0
hoa/exception Version ~1.0
hoa/file Version ~1.0
hoa/protocol Version ~1.0
hoa/visitor Version ~2.0