caret / packages / math / src / nodes / decimal.ts

import { CaretNode, h, t, VNode } from "@caret-js/core";
import { MathExpressionTag } from "../tags/mathExpression";
import { CanBeAdjacentMultRightSideTag } from "../parselets/adjacentMultiplication";
import { ParenthesesChildTag } from "../parselets/parentheses";

export class DecimalNode extends CaretNode {
  constructor(public value: string) {
    super();
    this.addTag(new MathExpressionTag()).addTag(
      new CanBeAdjacentMultRightSideTag<DecimalNode>(
        decimalAdjacentMultiplicationRightSideCheck
      )
    );
  }

  static from(value: string): DecimalNode {
    return new DecimalNode(value);
  }

  toFloat(): number {
    return parseFloat(this.value);
  }

  toDebugMathML(): VNode {
    return h("mn", {}, t(this.value));
  }
}

function decimalAdjacentMultiplicationRightSideCheck(
  left: CaretNode,
  right: DecimalNode
): boolean {
  if (right.hasTag(ParenthesesChildTag)) {
    return true;
  }

  // Decimal nodes on the right side of adjacent multiplication must be non-negative
  // For example, "x2" is "x multiplied by 2", but "x-2" is "x minus 2"
  if (right.toFloat() < 0) {
    return false;
  }

  if (left.hasTag(ParenthesesChildTag)) {
    return true;
  }

  if (left instanceof DecimalNode) {
    return false;
  }

  return false;
}