index.js

"use strict";

export default class PostgresInterval {
  constructor() {
    this.years = 0;
    this.months = 0;
    this.days = 0;
    this.hours = 0;
    this.minutes = 0;
    this.seconds = 0;
    this.milliseconds = 0;
  }

  toISOString() {
    return toISOString.call(this, { short: false });
  }

  toISOStringShort() {
    return toISOString.call(this, { short: true });
  }
}

const propertiesISOEquivalent = {
  years: "Y",
  months: "M",
  days: "D",
  hours: "H",
  minutes: "M",
  seconds: "S",
};

function toISOString({ short }) {
  let datePart = "";
  if (!short || this.years) {
    datePart += this.years + propertiesISOEquivalent.years;
  }
  if (!short || this.months) {
    datePart += this.months + propertiesISOEquivalent.months;
  }
  if (!short || this.days) {
    datePart += this.days + propertiesISOEquivalent.days;
  }
  let timePart = "";
  if (!short || this.hours) {
    timePart += this.hours + propertiesISOEquivalent.hours;
  }
  if (!short || this.minutes) {
    timePart += this.minutes + propertiesISOEquivalent.minutes;
  }
  if (!short || this.seconds || this.milliseconds) {
    if (this.milliseconds) {
      timePart +=
        Math.trunc((this.seconds + this.milliseconds / 1000) * 1000000) /
          1000000 +
        propertiesISOEquivalent.seconds;
    } else {
      timePart += this.seconds + propertiesISOEquivalent.seconds;
    }
  }
  if (!timePart && !datePart) {
    return "PT0S";
  }
  if (!timePart) {
    return `P${datePart}`;
  }
  return `P${datePart}T${timePart}`;
}

const position = { value: 0 };

function readNextNum(interval) {
  let val = 0;
  while (position.value < interval.length) {
    const char = interval[position.value];
    if (char >= "0" && char <= "9") {
      val = val * 10 + +char;
      position.value++;
    } else {
      break;
    }
  }
  return val;
}

function parseMillisecond(interval) {
  const previousPosition = position.value;
  const currentValue = readNextNum(interval);
  const valueStringLength = position.value - previousPosition;
  switch (valueStringLength) {
    case 1:
      return currentValue * 100;
    case 2:
      return currentValue * 10;
    case 3:
      return currentValue;
    case 4:
      return currentValue / 10;
    case 5:
      return currentValue / 100;
    case 6:
      return currentValue / 1000;
  }
  // slow path
  const remainder = valueStringLength - 3;
  return currentValue / Math.pow(10, remainder);
}

function parseInterval(instance, interval) {
  if (!interval) {
    return;
  }
  position.value = 0;
  let currentValue;
  let nextNegative = 1;
  while (position.value < interval.length) {
    const char = interval[position.value];
    if (char === "-") {
      nextNegative = -1;
      position.value++;
      continue;
    } else if (char === "+") {
      position.value++;
      continue;
    } else if (char === " ") {
      position.value++;
      continue;
    } else if (char < "0" || char > "9") {
      position.value++;
      continue;
    } else {
      currentValue = readNextNum(interval);
      if (interval[position.value] === ":") {
        instance.hours = currentValue ? nextNegative * currentValue : 0;
        position.value++;
        currentValue = readNextNum(interval);
        instance.minutes = currentValue ? nextNegative * currentValue : 0;
        position.value++;
        currentValue = readNextNum(interval);
        instance.seconds = currentValue ? nextNegative * currentValue : 0;
        if (interval[position.value] === ".") {
          position.value++;
          currentValue = parseMillisecond(interval);
          instance.milliseconds = currentValue
            ? nextNegative * currentValue
            : 0;
        }
        return;
      }
      // skip space
      position.value++;
      const unit = interval[position.value];
      if (unit === "y") {
        instance.years = currentValue ? nextNegative * currentValue : 0;
      } else if (unit === "m") {
        instance.months = currentValue ? nextNegative * currentValue : 0;
      } else if (unit === "d") {
        instance.days = currentValue ? nextNegative * currentValue : 0;
      }
      nextNegative = 1;
    }
  }
}

export function parse(interval) {
  const instance = {
    years: 0,
    months: 0,
    days: 0,
    hours: 0,
    minutes: 0,
    seconds: 0,
    milliseconds: 0,
  };
  if (typeof interval === 'string') {
    parseInterval(instance, interval);
  } else {
    Object.assign(instance, interval);
  }
  return instance;
}