parseUtil.ts

export class ParseLocation {
  constructor(
      public file: ParseSourceFile, public offset: number, public line: number,
      public col: number) {}

  toString(): string {
    return this.offset ? `${this.file.url}@${this.line}:${this.col}` : this.file.url;
  }
}

export class ParseSourceFile {
  constructor(public content: string, public url: string) {}
}

export class ParseSourceSpan {
  constructor(
      public start: ParseLocation, public end: ParseLocation, public details: string = null) {}

  toString(): string {
    return this.start.file.content.substring(this.start.offset, this.end.offset);
  }
}

export enum ParseErrorLevel {
  WARNING,
  FATAL
}

export abstract class ParseError {
  constructor(
      public span: ParseSourceSpan, public msg: string,
      public level: ParseErrorLevel = ParseErrorLevel.FATAL) {}

  toString(): string {
    var source = this.span.start.file.content;
    var ctxStart = this.span.start.offset;
    var contextStr = '';
    var details = '';
    if (ctxStart) {
      if (ctxStart > source.length - 1) {
        ctxStart = source.length - 1;
      }
      var ctxEnd = ctxStart;
      var ctxLen = 0;
      var ctxLines = 0;

      while (ctxLen < 100 && ctxStart > 0) {
        ctxStart--;
        ctxLen++;
        if (source[ctxStart] === '\n') {
          if (++ctxLines === 3) {
            break;
          }
        }
      }

      ctxLen = 0;
      ctxLines = 0;
      while (ctxLen < 100 && ctxEnd < source.length - 1) {
        ctxEnd++;
        ctxLen++;
        if (source[ctxEnd] === '\n') {
          if (++ctxLines === 3) {
            break;
          }
        }
      }

      let context = source.substring(ctxStart, this.span.start.offset) + '[ERROR ->]' +
          source.substring(this.span.start.offset, ctxEnd + 1);
      contextStr = ` ("${context}")`;
    }
    if (this.span.details) {
      details = `, ${this.span.details}`;
    }
    return `${this.msg}${contextStr}: ${this.span.start}${details}`;
  }
}