Function parseExpression

packages/plugin-plot/src/plot-utils.ts:19–51

(expression: string, get: (path: string) => any)

}

export function parseExpression(expression: string, get: (path: string) => any) {
  const parsed = math.parse(expression)
  const symbols = getSymbols(parsed)
  const scope = symbols.reduce((acc, path) => {
    const symbol = get(path)
    if (!symbol) throw Error(`Invalid symbol at path \`${path}\``)
    return Object.assign(acc, { [path]: symbol })
  }, {} as { [key in keyof typeof symbols]: any })

  let _formattedString = parsed.toString()

  for (let key in scope) {
    const re = new RegExp(`\\b${key}\\b`, 'g')
    // TODO check type better than this
    const s = typeof scope[key] === 'function' ? scope[key].__parsedScoped.toString() : scope[key]
    _formattedString = _formattedString.replace(re, s)
  }

  const parsedScoped = math.parse(_formattedString)
  const compiled = parsedScoped.compile()

  function expr(v: number) {
    return compiled.evaluate({ x: v })
  }

  Object.assign(expr, {
    __parsedScoped: parsedScoped,
    __parsed: parsed,
    __symbols: symbols,
  })

  return expr
}