parallax-loader

Parallax ini library

Parallax config is configuration schema that is widely used within Microsoft Bing. The config is usually expressed in ini file with a schema file.

Example

Assume there is a typescript schema file as below

export interface MainConfig {
    Label: string;
    Cnt: number;
    Sub: SubConfig;
}

export interface SubConfig {
    Enabled: boolean;
    Arr: number[];
    Map: Record<string, number>;
}

And there is ini file as below,

[main]
_type=MainConfig
Label=sample
Cnt&param1:value1=8
Cnt=9
Sub&param1:value1&param2:value2=sub1
Sub=sub

[sub]
_type=SubConfig
Enabled=false
Arr=1,2,3
Map&param3:value3=A:0,B:1,C:2
Map=A:1,B:2,C:3

[sub1]
_type=SubConfig
Enabled=true
Arr&param3:value3=5,6,7
Arr=4,5,6
Map=A:2,B:3,C:4

In the ini file above, each section corresponds to one specific interface. Value of _type would be same as interface name. The key of each config line correponds to field of the interface with some constraints. For example, Arr&param3:value3=2,3,4 means when param3:value3 condition matches, its value is [2,3,4].
And if there is reference to CustomType, it should be represented by section name for the the CustomType, like Sub=sub should point to section sub.
Currently the library supports list and map (which is Record in typescript). List would be represented by string seperataed by ','. Map would be represented by string seperated by ',' as well and its key and value would be seperated by ':'.
Please notice that, in current version, only line after trimmed starts with ';' would be treated as comment line.

Constraint combination

In parallax config, we could easily express constraint combination. Take the ini config below for example,

[main]
_type=Config
Probability&reg:east&gender:female=0.8
Probability&reg:east&gender:male=0.7
Probability&reg:west&gender:female=0.5
Probability&reg:west&gender:male=0.4
Probability=0.1

As you could see from ini file, we could express some probability with region and gender combination. Once specific constraints recieved, we could get related resolved Probability value without checking different condition combinations.

Configuration Resolve

For the ini file above, each field value is resolved by matching the constraints attached with order as prioerity. For example, if only param3:value3 matches, then MainConfig would be resolved as below,

{
    Label: "sample",
    Cnt: 9,
    Sub: {
        Enabled: false,
        Arr: [1, 2, 3],
        Map: {
            A: 0,
            B: 1,
            C: 2
        }
    }
}

If param1:value1&param2:value2 matches, param1:value1 matches as well, then MainConfig would be resolved as below,

{
    Label: "sample",
    Cnt: 8,
    Sub: {
        Enabled: true,
        Arr: [4,5,6],
        Map: {
            A: 2,
            B: 3,
            C: 4
        }
    }
}

Please notice that the library assumes that the resolved config would be parsed from the first section of the ini file.

Supported types

Currently the library supports types as below in typescript,

• string
• number
• boolean
• enum
• CustomType
• string[]
• number[]
• boolean[]
• enum[]
• CustomType[]
• Record<string, string>
• Record<string, number>
• Record<string, boolean>
• Record<string, enum>
• Record<string, CustomType>

For custom defined enum, it should have non-negative integer assigned to each field.

Development Setup

Please install vscode as IDE.

# install
npm install

# build
npm run build

# run test
npm run test

# run lint
npm run lint

To debug test case, please set configuration to be Jest Current File, open test file and run Start Debugging from vscode menu.
To debug main.ts from example folder, please update the module to be CommonJS in tsconfig.json, set configuration to be Launch Example Gen and run Start Debugging from vscode menu. Please do remember to revert the module change back to ESNext for building and running tests.

Usage

The library would be published as npm package parallax-loader which is actually a webpack loader. If your bundle tools is webpack, then you could define a rule as below,

{
    test: /\.ini$/,
    use: [
        {
            loader: 'parallax-loader',
            options: {
                schema: path.resolve(__dirname, '../src/Config.ts')
            }
        }
    ]
}

Then you could load the ini file in code as below,

const configLoadFunc = rquire('./Config.ini')
const config = configLoadFunc(['reg:south'])

Please check more in Demo Folder.
If you don't have any bundle tool, then you run the built gen.js with node.js, to generate output typescript file under the same folder of schema file, which would be ConfigGen.ts for the command below,

node gen.js ./src/Config.ts ./src/Config.ini

And you could import generateConfig from the genreated file and resolve config with constraint list. For example,

import {generateConfig} from "./ConfigGen"
const config = generateConfig(['reg:south'])

To generate js code, add --js as below,

node gen.js ./src/Config.ts ./src/Config.ini --js

You could also resolved config with code below,

const configLoadFunc = require("./ConfigGen")
const config = configLoadFunc(["reg:south"])

If you have the parallax-loader installed, gen.js is also generated as part of the library. Then you could run command like below as well.

node node_modules/parallax-loader/dist/gen.js ./src/Config.ts ./src/Config.ini --js

And you could add this command to the build/debug command, which would be like a webpack loader to automatically update the generated code if you change the schema/configuration file. For example,

{
    "scripts": {
        "code_gen": "node node_modules/parallax-loader/dist/gen.js ./src/Config.ts ./src/Config.ini --js",
        "build_inner": "some build command",
        "build": "npm run code_gen && npm run build_inner"
    }
}