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import { isObject } from "../utils"
export type Operand = string | number | { reference: string }
type Operator = "+" | "-" | "*" | "/"
function resolveReference(operand: Operand): string {
if (isObject(operand) && operand.reference) {
return operand.reference
}
return String(operand)
}
const toExpression = (operator: Operator, ...operands: Array<Operand>) =>
operands.map(resolveReference).join(` ${operator} `).replace(/calc/g, "")
const add = (...operands: Array<Operand>) =>
`calc(${toExpression("+", ...operands)})`
const subtract = (...operands: Array<Operand>) =>
`calc(${toExpression("-", ...operands)})`
const multiply = (...operands: Array<Operand>) =>
`calc(${toExpression("*", ...operands)})`
const divide = (...operands: Array<Operand>) =>
`calc(${toExpression("/", ...operands)})`
const negate = (x: Operand) => {
const value = resolveReference(x)
if (value != null && !Number.isNaN(parseFloat(value))) {
return String(value).startsWith("-") ? String(value).slice(1) : `-${value}`
}
return multiply(value, -1)
}
interface CalcChain {
add: (...operands: Array<Operand>) => CalcChain
subtract: (...operands: Array<Operand>) => CalcChain
multiply: (...operands: Array<Operand>) => CalcChain
divide: (...operands: Array<Operand>) => CalcChain
negate: () => CalcChain
toString: () => string
}
export const calc = Object.assign(
(x: Operand): CalcChain => ({
add: (...operands) => calc(add(x, ...operands)),
subtract: (...operands) => calc(subtract(x, ...operands)),
multiply: (...operands) => calc(multiply(x, ...operands)),
divide: (...operands) => calc(divide(x, ...operands)),
negate: () => calc(negate(x)),
toString: () => x.toString(),
}),
{
add,
subtract,
multiply,
divide,
negate,
},
)
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