engine-runner

@putout/engine-runner

Run 🐊Putout plugins.

Install

npm i @putout/engine-runner

Supported Plugin Types

There is a couple plugin types available in 🐊Putout:

• ✅ Declarator
• ✅ Replacer
• ✅ Includer
• ✅ Traverser
• ✅ Finder

All of them supports subset of JavaScript 🦎PutoutScript described in @putout/compare.

They goes from simplest to hardest. Let's start from Declarator.

Declarator

The simplest possible type of plugin, even simpler then Replacer:

module.exports.declare = () => ({
    isString: `const isString = (a) => typeof a === 'string'`,
});

Based on @putout/operator-declare, helps to add declaration to any referenced Identifier.

Replacer

Replacer converts code in declarative way. Simplest possible form, no need to use fix. Just from and to parts according to template variables syntax.

Simplest replace example:

module.exports.report = () => 'any message here';

module.exports.replace = () => ({
    'const a = 1': 'const b = 1',
});

// optional
module.exports.filter = (path) => {
    return true;
};

// optional
module.exports.match = () => ({
    'const __a = 1': ({__a}) => {
        return true;
    },
});

// optional
module.exports.exclude = () => [
    `const hello = 'world'`,
    'ArrowFunctionExpression',
];

Simplest remove example:

module.exports.report = () => 'debugger should not be used';

module.exports.replace = () => ({
    debugger: '',
});

// debugger; alert(); -> alert();

Templates:

module.exports.report = () => 'any message here';

module.exports.replace = () => ({
    'var __a = 1': 'const __a = 1',
});

// var x = 1; -> const x = 1;

A couple variables example:

module.exports.report = () => 'any message here';

module.exports.replace = () => ({
    'const __a = __b': 'const __b = __a',
});

// const hello = world; -> const world = hello;

Processing of node using functions

You can pass a function as object value for more soficticated processing.

Remove node:

module.exports.report = () => 'any message here';

module.exports.replace = () => ({
    'for (const __a of __b) __c': ({__a, __b, __c}, path) => {
        // remove node
        return '';
    },
});

// for (a of b) {}; alert(); -> alert();

Update node:

module.exports.report = () => 'any message here';

module.exports.replace = () => ({
    'for (const __a of __array) __c': ({__a, __array, __c}, path) => {
        // update __array elements
        path.node.right.elements = [];
        return path;
    },
});

// for (const a of [1, 2, 3]) {}; -> for (const a of []) {};

Update node using template variables:

module.exports.report = () => 'any message here';

module.exports.replace = () => ({
    'for (const __a of __array) __c': ({__a, __array, __c}, path) => {
        // update the whole node using template string
        return 'for (const x of y) z';
    },
});

// for (const item of array) {}; -> for (const x of y) z;

Includer

Includer is the most preferable format of a plugin, simplest to use (after Replacer):

module.exports.report = () => 'debugger statement should not be used';

module.exports.fix = (path) => {
    path.remove();
};

module.exports.include = () => [
    'debugger',
];

// optional
module.exports.exclude = () => {
};

// optional
module.exports.filter = (path) => {
    return true;
};

include and exclude returns an array of @babel/types, or code blocks:

const __ = 'hello';

Where __ can be any node. All this possible with help of @putout/compare. Templates format supported in traverse and find plugins as well.

Traverser

Traverser gives you more power to filter and fix nodes you need.

module.exports.report = () => 'debugger statement should not be used';

module.exports.fix = (path, {options}) => {
    path.remove();
};

module.exports.traverse = ({push}) => ({
    'debugger'(path) {
        push(path);
    },
});

Finder

Finder gives you all the control over traversing, but it's the slowest format. Because traversers not merged in contrast with other plugin formats.

module.exports.report = () => 'debugger statement should not be used';

module.exports.fix = (path) => {
    path.remove();
};

module.exports.find = (ast, {push, traverse}) => {
    traverse(ast, {
        'debugger'(path) {
            push(path);
        },
    });
};

Example

const {runPlugins} = require('@putout/engine-runner');
const {parse} = require('@putout/engine-parser');

const plugins = [{
    rule: 'remove-debugger',
    msg: '', // optional
    options: {}, // optional
    plugin: {
        include: () => ['debugger'],
        fix: (path) => path.remove(),
        report: () => `debugger should not be used`,
    },
}];

const ast = parse('const m = "hi"; debugger');
const places = runPlugins({
    ast,
    shebang: false, // default
    fix: false, // default
    fixCount: 0, // default
    plugins,
    parser: 'babel', // default
});

Stores

Stores is preferred way of keeping 🐊Putout data, traverse init function called only once, and any other way of handling variables will most likely will lead to bugs. There is a couple store types:

• ✅ listStore;
• ✅ pathStore;
• ✅ store;
• ✅ upstore;
• ✅ uplist;

Let's talk about each of them.

listStore

To save things as a list without duplicates use listStore. Let's suppose you have such code:

debugger;
const hello = '';
debugger;
const world = '';

Let's process it!

module.exports.traverse = ({listStore}) => ({
    'debugger'(path) {
        listStore(path);
    },
    
    Program: {
        exit() {
            console.log(listStore());
            // returns
            [{type: 'DebuggerStatement'}, {type: 'DebuggerStatement'}];
            // for code
            'debugger; debugger';
        },
    },
});

pathStore

When you want additional check that path not removed.

debugger;
const hello = '';

Let's process it!

module.exports.traverse = ({pathStore}) => ({
    'debugger'(path) {
        pathStore(path);
        path.remove();
    },
    
    Program: {
        exit() {
            console.log(pathStore());
            // returns
            [];
        },
    },
});

store

When you need key-value use store:

module.exports.traverse = ({push, store}) => ({
    'debugger'(path) {
        store('hello', 'world');
        push(path);
    },
    
    Program: {
        exit() {
            store();
            // returns
            ['world'];
            
            store.entries();
            // returns
            [['hello', 'world']];
            
            store('hello');
            // returns
            'world';
        },
    },
});

upstore

When you need to update already saved values, use upstore:

module.exports.traverse = ({push, store}) => ({
    TSTypeAliasDeclaration(path) {
        if (path.parentPath.isExportNamedDeclaration())
            return;
        
        store(path.node.id.name, {
            path,
        });
    },
    
    ObjectProperty(path) {
        const {value} = path.node;
        const {name} = value;
        
        store(name, {
            used: true,
        });
    },
    
    Program: {
        exit() {
            for (const {path, used} of store()) {
                if (used)
                    continue;
                
                push(path);
            }
        },
    },
});

uplist

When you need to update named arrays:

module.exports.traverse = ({uplist, push}) => ({
    'const __object = __a.__b': (fullPath) => {
        const {__a, __b} = getTemplateValues(fullPath, 'const __object = __a.__b');
        const initPath = fullPath.get('declarations.0.init');
        const {uid} = initPath.scope;
        
        if (isIdentifier(__a) || isCallExpression(__a)) {
            const {code} = generate(__a);
            const id = `${uid}-${code}`;
            
            return uplist(id, initPath);
        }
    },
    'Program': {
        exit: () => {
            for (const items of uplist()) {
                if (items.length < 2)
                    continue;
                
                const index = items.length - 1;
                const path = items[index];
                
                push({
                    path,
                    items,
                });
            }
        },
    },
});

Logs

To see logs, use:

• ✅ DEBUG=putout:runner:*
• ✅ DEBUG=putout:runner:fix
• ✅ DEBUG=putout:runner:find
• ✅ DEBUG=putout:runner:template
• ✅ DEBUG=putout:runner:replace

License

MIT