prettier-swagger-plugin.ts

import { ParserOptions, FastPath, Doc, doc, Plugin, AST } from 'prettier';
import { parsers as bundledParsers } from 'prettier/parser-babel';

const { concat, indent, hardline, join } = doc.builders;

// Modified from https://github.com/prettier/prettier/blob/master/src/language-js/printer-estree-json.js
const print = (path: FastPath, _: ParserOptions, print: (path: FastPath) => Doc): Doc => {
  const node = path.getValue();
  switch (node.type) {
    case "JsonRoot":
      return concat([path.call(print, "node"), hardline]);
    case "ArrayExpression":
      return node.elements.length === 0
        ? "[]"
        : concat([
          "[",
          indent(
            concat([
              hardline,
              join(concat([",", hardline]), path.map(print, "elements"))
            ])
          ),
          hardline,
          "]"
        ]);
    case "ObjectExpression":
      return node.properties.length === 0
        ? "{}"
        : concat([
          "{",
          indent(
            concat([
              hardline,
              join(concat([",", hardline]), path.map(print, "properties"))
            ])
          ),
          hardline,
          "}"
        ]);
    case "ObjectProperty":
      return concat([path.call(print, "key"), ": ", path.call(print, "value")]);
    case "UnaryExpression":
      return concat([
        node.operator === "+" ? "" : node.operator,
        path.call(print, "argument")
      ]);
    case "NullLiteral":
      return "null";
    case "BooleanLiteral":
      return node.value ? "true" : "false";
    case "StringLiteral":
      return JSON.stringify(node.value);
    case "NumericLiteral":
      // Modified: Keep numeric literal as-is
      return node.extra.raw;
    case "Identifier":
      return JSON.stringify(node.name);
    default:
      /* istanbul ignore next */
      throw new Error("unknown type: " + JSON.stringify(node.type));
  }
}

const preprocess = (ast: AST, _: any): AST => {
  return Object.assign({}, ast, {
    type: "JsonRoot",
    node: ast,
    comments: []
  });
}

export const languages: Plugin['languages'] = [
  {
    name: 'json-swagger',
    extensions: ['.json'],
    parsers: ['json-swagger']
  }
]

export const parsers = {
  'json-swagger': {
    ...bundledParsers['json-stringify'],
    astFormat: 'estree-swagger-customized'
  }
};

export const printers = {
  'estree-swagger-customized': {
    preprocess,
    print
  }
};