incode is a library for building code injectors.

Code with injectable regions:

class User {
  // inj:emit("User", "pck")
  // inj:end
}

Code injector:

import { createDirectiveMatcher, inject } from "incode";

const s = inject(
  text, // code with injectable regions
  createDirectiveMatcher("inj"),
  (region) => {
    return `${region.args[1]}() { console.log("${region.args[0]} injected method"); }`;
  },
);

Result after injection:

// inj:assign({ schema: "User" })
class User {
  // inj:emit("pck")
  pck() { console.log("User injected method"); }
  // inj:end
}

• Block-scoped variables
• Indentation autodection for injectable regions
• Automatic removal of existing code in injectable regions

• begin - begin local scope
• end - end region
• assign(data: JSON) - assign data to a local scope Object.assign
• merge(data: JSON) - merge data to a local scope _.merge
• emit(...args: Array<JSON>) - emit code

function createDirectiveMatcher(prefix: string): RegExp;

createDirectiveMatcher creates a RegExp object that will be used as a directive matcher.

interface InjectableRegion {
  readonly args: any[];
  readonly data: {};
  readonly padding: string;
  readonly start: number;
  readonly end: number;
}

function extractRegions(
  text: string,
  directiveMatcher: RegExp,
  data = {},
): InjectableRegion[];

extractRegions extracts InjectableRegions from text.

function inject(
  text: string,
  directiveMatcher: RegExp,
  cb: (region: InjectableRegion) => string,
  data = {},
): string;

inject invokes cb function and injects its result into a text.