json.ts

import { ParserError } from "../util/errors.js";
import type { FileInfo } from "../types/index.js";
import type { Plugin } from "../types/index.js";

export default {
  /**
   * The order that this parser will run, in relation to other parsers.
   */
  order: 100,

  /**
   * Whether to allow "empty" files. This includes zero-byte files, as well as empty JSON objects.
   */
  allowEmpty: true,

  /**
   * Determines whether this parser can parse a given file reference.
   * Parsers that match will be tried, in order, until one successfully parses the file.
   * Parsers that don't match will be skipped, UNLESS none of the parsers match, in which case
   * every parser will be tried.
   */
  canParse: ".json",

  /**
   * Allow JSON files with byte order marks (BOM)
   */
  allowBOM: true,

  /**
   * Parses the given file as JSON
   */
  async parse(file: FileInfo): Promise<object | undefined> {
    let data = file.data;
    if (Buffer.isBuffer(data)) {
      data = data.toString();
    }

    if (typeof data === "string") {
      if (data.trim().length === 0) {
        return; // This mirrors the YAML behavior
      } else {
        try {
          return JSON.parse(data);
        } catch (e: any) {
          if (this.allowBOM) {
            try {
              // find the first curly brace
              const firstCurlyBrace = data.indexOf("{");
              // remove any characters before the first curly brace
              data = data.slice(firstCurlyBrace);
              return JSON.parse(data);
            } catch (e: any) {
              throw new ParserError(e.message, file.url);
            }
          }
          throw new ParserError(e.message, file.url);
        }
      }
    } else {
      // data is already a JavaScript value (object, array, number, null, NaN, etc.)
      return data as object;
    }
  },
} as Plugin;