repo_description: A reference implementation of GraphQL for JavaScript
repo_topics: graphql graphql-js
code: import { devAssert } from '../jsutils/devAssert';
  import { inspect } from '../jsutils/inspect';
  import { instanceOf } from '../jsutils/instanceOf';
  
  interface Location {
    line: number;
    column: number;
  }
  
  /**
   * A representation of source input to GraphQL. The `name` and `locationOffset` parameters are
   * optional, but they are useful for clients who store GraphQL documents in source files.
   * For example, if the GraphQL input starts at line 40 in a file named `Foo.graphql`, it might
   * be useful for `name` to be `"Foo.graphql"` and location to be `{ line: 40, column: 1 }`.
   * The `line` and `column` properties in `locationOffset` are 1-indexed.
   */
  export class Source {
    body: string;
    name: string;
    locationOffset: Location;
  
    constructor(
      body: string,
      name: string = 'GraphQL request',
      locationOffset: Location = { line: 1, column: 1 },
    ) {
      devAssert(
        typeof body === 'string',
        `Body must be a string. Received: ${inspect(body)}.`,
      );
  
      this.body = body;
      this.name = name;
      this.locationOffset = locationOffset;
      devAssert(
        this.locationOffset.line > 0,
        'line in locationOffset is 1-indexed and must be positive.',
      );
      devAssert(
        this.locationOffset.column > 0,
        'column in locationOffset is 1-indexed and must be positive.',
      );
    }
  
    get [Symbol.toStringTag]() {
      return 'Source';
    }
  }
  
  /**
   * Test if the given value is a Source object.
   *
   * @internal
   */
  export function isSource(source: unknown): source is Source {
    return instanceOf(source, Source);
  }
  