import {
  CaretNode,
  CaretParser,
  CaretPrefixParselet,
  TokensTag,
} from "@caret-js/core";
import { CharToken } from "@caret-js/core";
import { PositiveNode } from "../nodes/positive";

// This parselet looks for a sequence of `CharToken`s that form a decimal number,
// meaning it has digits, optionally a single decimal point, and more digits. The digits
// are optional on either side of the decimal point, but at least one digit must be present.

export class UnaryPlusParselet extends CaretPrefixParselet {
  parse(parser: CaretParser): CaretNode {
    const token = parser.consume();
    this.assert(
      token instanceof CharToken && token.char === "+",
      "Expected '+' token"
    );

    const child = parser.parseMinBP(this);
    return PositiveNode.from(child).addTag(new TokensTag([token]));
  }
}