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import { Node } from "./types/Node.ts";
import { Parser, ParseText } from "./types/Parser.ts";

export const or = (parsers: Parser[]): Parser => {
  const { length } = parsers;

  return (text, position, rootParser) => {
    for (let i = 0; i < length; i++) {
      const match = parsers[i](text, position, rootParser);

      if (match) {
        return match;
      }
    }

    return null;
  };
};

export const regexp = (
  pattern: RegExp,
  callback: (
    match: string[],
    text: string,
    position: number,
    parseText: ParseText,
  ) => [Node, number] | null,
): Parser =>
(text, position, parseText) => {
  const match = text.substring(position).match(pattern);

  if (!match) {
    return null;
  }

  return callback(match, text, position, parseText);
};

export const explicit = (parser: Parser): Parser =>
(
  text,
  position,
  parseText,
) => {
  const prevChar = text.charAt(position - 1);

  if (prevChar && !prevChar.match(/[\s.,([{!?\-=]/)) {
    return null;
  }

  return parser(text, position, parseText);
};

export const topOfLine = (parser: Parser): Parser =>
(
  text,
  position,
  parseText,
) => {
  if (position > 0 && text.charAt(position - 1) !== "\n") {
    return null;
  }

  return parser(text, position, parseText);
};