ivi/src/template/parser.ts

Lightweight Embeddable Web UI Library.

export class TemplateParserError extends Error {
  staticsOffset: number;
  textOffset: number;

  constructor(message: string, staticsOffset: number, textOffset: number) {
    super(message);
    this.staticsOffset = staticsOffset;
    this.textOffset = textOffset;
  }
}

export class TemplateScanner {
  readonly statics: string[] | TemplateStringsArray;
  readonly exprCount: number;
  text: string;
  i: number;
  e: number;

  constructor(statics: string[] | TemplateStringsArray) {
    if (statics.length === 0) {
      throw new TemplateParserError("Template is empty.", 0, 0);
    }

    this.statics = statics;
    this.exprCount = statics.length - 1;
    this.text = statics[0];
    this.i = 0;
    this.e = 0;
  }

  isEnd(): boolean {
    return (
      this.i === this.text.length &&
      this.e === this.exprCount
    );
  }

  peekCharCode(i: number = 0): number {
    i += this.i;
    return i < this.text.length
      ? this.text.charCodeAt(i)
      : -1;
  }

  charCode(c: number): boolean {
    if (this.i < this.text.length && this.text.charCodeAt(this.i) === c) {
      this.i++;
      return true;
    }
    return false;
  }

  peekExpr(): number {
    const e = this.e;
    return (e < this.exprCount && this.i === this.text.length)
      ? e
      : -1;
  }

  expr(): number {
    const e = this.e;
    if (e < this.exprCount && this.i === this.text.length) {
      this.i = 0;
      this.text = this.statics[++this.e];
      return e;
    }
    return -1;
  }

  peekString(s: string): boolean {
    const text = this.text;
    const end = this.i + s.length;
    return (
      end <= text.length &&
      text.substring(this.i, end) === s
    );
  }

  string(s: string): boolean {
    const r = this.peekString(s);
    if (r) {
      this.i += s.length;
    }
    return r;
  }

  peekRegExp(re: RegExp): string | undefined {
    if (!re.sticky) {
      throw Error("RegExp should have a sticky flag.");
    }

    re.lastIndex = this.i;
    const match = re.exec(this.text);
    if (match !== null) {
      return match[0];
    }
  }

  regExp(re: RegExp): string | undefined {
    const r = this.peekRegExp(re);
    if (r !== void 0) {
      this.i += r.length;
    }
    return r;
  }
}

/**
 * Formats error message.
 *
 * @param errorMsg Error message.
 * @param errorCol Line column.
 */
const formatErrorMsg = (errorMsg: string, errorCol: number): string => {
  let msg = "";
  while (--errorCol >= 0) {
    msg += " ";
  }
  msg += "^\nError: " + errorMsg + "\n";
  return msg;
};

/**
 * Formats compiler errors.
 *
 * @param statics Statics.
 * @param errorMsg Error message.
 * @param staticsOffset Expression offset.
 * @param textOffset Text offset.
 * @returns Formatted error message.
 */
export const formatError = (
  statics: TemplateStringsArray,
  errorMsg: string,
  staticsOffset: number,
  textOffset: number,
): string => {
  for (let i = 0; i < staticsOffset; i++) {
    if (i > 0) {
      textOffset += 4 + (Math.log10(i) | 0); // ${i}
    }
    textOffset += statics[i].length;
  }

  let msg = "\n";
  let text = statics[0];
  for (let i = 1; i < statics.length; i++) {
    text += "${" + (i - 1) + "}" + statics[i];
  }

  for (const line of text.split("\n")) {
    msg += line + "\n";
    if (textOffset >= 0 && textOffset < line.length) {
      msg += formatErrorMsg(errorMsg, textOffset);
    }
    textOffset -= (line.length + 1);
  }

  if (textOffset >= 0) {
    msg += formatErrorMsg(errorMsg, textOffset);
  }

  return msg;
};

/**
 * ASCII Char Codes.
 */
export const enum CharCode {
  /** "\\t" */Tab = 9,
  /** "\\n" */Newline = 10,
  /** "\\v" */VerticalTab = 11,
  /** "\\r" */CarriageReturn = 13,
  /** [space] */Space = 32,
  /** "!" */ExclamationMark = 33,
  /** "\\"" */DoubleQuote = 34,
  /** "#" */NumberSign = 35,
  /** "#" */Hash = 35,
  /** "$" */DollarSign = 36,
  /** "%" */PercentSign = 37,
  /** "&" */Ampersand = 38,
  /** "'" */SingleQuote = 39,
  /** "(" */LeftParen = 40,
  /** ")" */RightParen = 41,
  /** "*" */Asterisk = 42,
  /** "+" */PlusSign = 43,
  /** "," */Comma = 44,
  /** "-" */MinusSign = 45,
  /** "." */Dot = 46,
  /** "/" */Slash = 47,
  /** ":" */Colon = 58,
  /** ";" */Semicolon = 59,
  /** "<" */LessThan = 60,
  /** "=" */EqualsTo = 61,
  /** ">" */MoreThan = 62,
  /** "?" */QuestionMark = 63,
  /** "@" */AtSign = 64,
  /** "[" */LeftSquareBracket = 91,
  /** "\" */Backslash = 92,
  /** "]" */RightSquareBracket = 93,
  /** "^" */Caret = 94,
  /** "_" */Underscore = 95,
  /** "`" */GraveAccent = 96,
  /** "{" */LeftCurlyBrace = 123,
  /** "|" */VerticalBar = 124,
  /** "}" */RightCurlyBrace = 125,
  /** "~" */Tilde = 126,
}