vaasu070 / pya2l

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package description

the purpose of this package is to provide an easy way to access and navigate in a2l formatted file.
once the file has been loaded, a tree of Python objects is generated, allowing the user to access nodes.

installation

using pip

install the most recent version of the package (master branch) by running the following command: pip install git+https://github.com/Sauci/pya2l.git@master

or install the last released version of the package by running the following command: pip install pya2l

from source

this package uses ply package. if it is not already installed, install it first.
once the above prerequisite is installed:

• download the pya2l package
• unzip it
• move to the directory containing the setup.py file
• run the command python setup.py install

note: the above command might require privileged access to succeed.

example of usage

the bellow code snippet shows how properties of a node in an a2l string can be retrieved using this package.

from pya2l.parser import A2lParser as Parser

a2l_string = """
    /begin PROJECT project_name "example project"
        /begin MODULE first_module "first module long identifier"
            /begin CHARACTERISTIC
                example_of_characteristic
                "first characteristic long identifier"
                VALUE
                0
                DAMOS_SST
                0
                first_characteristic_conversion
                -4.5
                12.0
            /end CHARACTERISTIC
        /end MODULE
    /end PROJECT
"""

a2l = Parser(a2l_string)

# get a list of available properties for a specific node.
assert set(a2l.tree.project.get_properties()) == set(['name', 'module', 'header', 'long_identifier'])

# access nodes explicitly.
assert a2l.tree.project.module[0].characteristic[0].name == 'example_of_characteristic'
assert a2l.tree.project.module[0].characteristic[0].lower_limit == -4.5
assert a2l.tree.project.module[0].characteristic[0].upper_limit == 12.0

# access nodes by type.
assert a2l.get_node('CHARACTERISTIC')[0].name == 'example_of_characteristic'

# instantiate custom class for specified node.
from pya2l.parser.grammar.node import Characteristic


class CustomCharacteristic(Characteristic):
    def node(self):
        return 'my custom ' + super(CustomCharacteristic, self).node()


a2l = Parser(a2l_string, CHARACTERISTIC=CustomCharacteristic)

assert isinstance(a2l.tree.project.module[0].characteristic[0], CustomCharacteristic)
assert a2l.tree.project.module[0].characteristic[0].node() == 'my custom CHARACTERISTIC'

# convert node to json-formatted string.
from json import dumps as python_object_to_json_string

a2l = Parser("""
    /begin PROJECT project_name "example project"
        /begin MODULE first_module "first module long identifier"
        /end MODULE
    /end PROJECT
    """)

assert python_object_to_json_string(a2l.tree.project.json, sort_keys=True, indent=4) == """{
    "header": null,
    "long_identifier": "example project",
    "module": [
        {
            "a2ml": null,
            "axis_pts": [],
            "characteristic": [],
            "compu_method": [],
            "compu_tab": [],
            "compu_vtab": [],
            "compu_vtab_range": [],
            "frame": null,
            "function": [],
            "group": [],
            "if_data_module": [],
            "if_data_xcp": null,
            "long_identifier": "first module long identifier",
            "measurement": [],
            "mod_common": null,
            "mod_par": null,
            "name": "first_module",
            "node": "MODULE",
            "record_layout": [],
            "unit": [],
            "user_rights": [],
            "variant_coding": null
        }
    ],
    "name": "project_name",
    "node": "PROJECT"
}"""

limitations

currently, the a2ml-formatted content is only described in the grammar, but the content of the node cannot be accessed as described above.