nushell/crates/nu_plugin_python/plugin.py
2021-12-19 10:00:31 +00:00

418 lines
16 KiB
Python

# Example of using python as script to create plugins for nushell
#
# The example uses JSON encoding but it should be a similar process using
# capnp proto to move data betwee nushell and the plugin. The only difference
# would be that you need to compile the schema file in order have the objects
# that decode and encode information that is read and written to stdin and stdour
#
# To register the plugin use:
# register <path-to-py-file> -e json
#
# Be carefull with the spans. Miette will crash if a span is outside the
# size of the contents vector. For this example we are using 0 and 1, which will
# point to the beginning of the contents vector. We strongly suggest using the span
# found in the plugin call head
#
# The plugin will be run using the active python implementation. If you are in
# a python environment, that is the python version that is used
#
# Note: To keep the plugin simple and without dependencies, the dictionaries that
# represent the data transferred between nushell and the plugin are kept as
# native python dictionaries. The encoding and decoding process could be improved
# by using libraries like pydantic and marshmallow
#
# This plugin uses python3
# Note: To debug plugins write to stderr using sys.stderr.write
import sys
import json
def signatures():
"""
Multiple signatures can be sent to nushell. Each signature will be registered
as a different plugin function in nushell.
In your plugin logic you can use the name of the signature to indicate what
operation should be done with the plugin
"""
return {
"Signature": [
{
"name": "nu-python",
"usage": "Signature test for python",
"extra_usage": "",
"required_positional": [
{
"name": "a",
"desc": "required integer value",
"shape": "Int",
"var_id": None,
},
{
"name": "b",
"desc": "required string value",
"shape": "String",
"var_id": None,
},
],
"optional_positional": [
{
"name": "opt",
"desc": "Optional number",
"shape": "Int",
"var_id": None,
}
],
"rest_positional": {
"name": "rest",
"desc": "rest value string",
"shape": "String",
"var_id": None,
},
"named": [
{
"long": "help",
"short": "h",
"arg": None,
"required": False,
"desc": "Display this help message",
"var_id": None
},
{
"long": "flag",
"short": "f",
"arg": None,
"required": False,
"desc": "a flag for the signature",
"var_id": None,
},
{
"long": "named",
"short": "n",
"arg": "String",
"required": False,
"desc": "named string",
"var_id": None,
},
],
"is_filter": False,
"creates_scope": False,
"category": "Experimental",
}
]
}
def process_call(plugin_call):
"""
plugin_call is a dictionary with the information from the call
It should contain:
- The name of the call
- The call data which includes the positional and named values
- The input from the pippeline
Use this information to implement your plugin logic
"""
# Pretty printing the call to stderr
sys.stderr.write(json.dumps(plugin_call, indent=4))
sys.stderr.write("\n")
# Creates a Value of type List that will be encoded and sent to nushell
return {
"Value": {
"List": {
"vals": [
{
"Record": {
"cols": ["one", "two", "three"],
"vals": [
{
"Int": {
"val": 0,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 0,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 0,
"span": {"start": 0, "end": 1},
}
},
],
"span": {"start": 0, "end": 1},
}
},
{
"Record": {
"cols": ["one", "two", "three"],
"vals": [
{
"Int": {
"val": 0,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 1,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 2,
"span": {"start": 0, "end": 1},
}
},
],
"span": {"start": 0, "end": 1},
}
},
{
"Record": {
"cols": ["one", "two", "three"],
"vals": [
{
"Int": {
"val": 0,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 2,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 4,
"span": {"start": 0, "end": 1},
}
},
],
"span": {"start": 0, "end": 1},
}
},
{
"Record": {
"cols": ["one", "two", "three"],
"vals": [
{
"Int": {
"val": 0,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 3,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 6,
"span": {"start": 0, "end": 1},
}
},
],
"span": {"start": 0, "end": 1},
}
},
{
"Record": {
"cols": ["one", "two", "three"],
"vals": [
{
"Int": {
"val": 0,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 4,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 8,
"span": {"start": 0, "end": 1},
}
},
],
"span": {"start": 0, "end": 1},
}
},
{
"Record": {
"cols": ["one", "two", "three"],
"vals": [
{
"Int": {
"val": 0,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 5,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 10,
"span": {"start": 0, "end": 1},
}
},
],
"span": {"start": 0, "end": 1},
}
},
{
"Record": {
"cols": ["one", "two", "three"],
"vals": [
{
"Int": {
"val": 0,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 6,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 12,
"span": {"start": 0, "end": 1},
}
},
],
"span": {"start": 0, "end": 1},
}
},
{
"Record": {
"cols": ["one", "two", "three"],
"vals": [
{
"Int": {
"val": 0,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 7,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 14,
"span": {"start": 0, "end": 1},
}
},
],
"span": {"start": 0, "end": 1},
}
},
{
"Record": {
"cols": ["one", "two", "three"],
"vals": [
{
"Int": {
"val": 0,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 8,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 16,
"span": {"start": 0, "end": 1},
}
},
],
"span": {"start": 0, "end": 1},
}
},
{
"Record": {
"cols": ["one", "two", "three"],
"vals": [
{
"Int": {
"val": 0,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 9,
"span": {"start": 0, "end": 1},
}
},
{
"Int": {
"val": 18,
"span": {"start": 0, "end": 1},
}
},
],
"span": {"start": 0, "end": 1},
}
},
],
"span": {"start": 0, "end": 1},
}
}
}
def plugin():
call_str = ",".join(sys.stdin.readlines())
plugin_call = json.loads(call_str)
if plugin_call == "Signature":
signature = json.dumps(signatures())
sys.stdout.write(signature)
elif "CallInfo" in plugin_call:
response = process_call(plugin_call)
sys.stdout.write(json.dumps(response))
else:
# Use this error format if you want to return an error back to nushell
error = {
"Error": {
"label": "ERROR from plugin",
"msg": "error message pointing to call head span",
"span": {"start": 0, "end": 1},
}
}
sys.stdout.write(json.dumps(error))
if __name__ == "__main__":
plugin()