commonMain.io.ktor.util.date.GMTDateParser.kt Maven / Gradle / Ivy
/*
* Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
*/
package io.ktor.util.date
/**
* Build [GMTDate] parser using [pattern] string.
*
* Pattern string format:
* | Unit | pattern char | Description |
* | -------- | ------------ | ---------------------------------------------------- |
* | Seconds | s | parse seconds 0 to 60 |
* | Minutes | m | parse minutes 0 to 60 |
* | Hours | h | parse hours 0 to 23 |
* | Month | M | parse month from Jan to Dec(see [Month] for details) |
* | Year | Y | parse year |
* | Any char | * | Match any character |
*/
public class GMTDateParser(private val pattern: String) {
init {
check(pattern.isNotEmpty()) { "Date parser pattern shouldn't be empty." }
}
/**
* Parse [GMTDate] from [dateString] using [pattern].
*/
public fun parse(dateString: String): GMTDate {
val builder = GMTDateBuilder()
var start = 0
var current = pattern[start]
var chunkStart = 0
var index = 1
try {
while (index < pattern.length) {
if (pattern[index] == current) {
index++
continue
}
val chunkEnd = chunkStart + index - start
builder.handleToken(current, dateString.substring(chunkStart, chunkEnd))
chunkStart = chunkEnd
start = index
current = pattern[index]
index++
}
if (chunkStart < dateString.length) {
builder.handleToken(current, dateString.substring(chunkStart))
}
} catch (_: Throwable) {
throw InvalidDateStringException(dateString, chunkStart, pattern)
}
return builder.build()
}
private fun GMTDateBuilder.handleToken(
type: Char,
chunk: String
): Unit = when (type) {
SECONDS -> {
seconds = chunk.toInt()
}
MINUTES -> {
minutes = chunk.toInt()
}
HOURS -> {
hours = chunk.toInt()
}
DAY_OF_MONTH -> {
dayOfMonth = chunk.toInt()
}
MONTH -> {
month = Month.from(chunk)
}
YEAR -> {
year = chunk.toInt()
}
ZONE ->
check(chunk == "GMT")
ANY -> Unit
else -> {
check(chunk.all { it == type })
}
}
public companion object {
public const val SECONDS: Char = 's'
public const val MINUTES: Char = 'm'
public const val HOURS: Char = 'h'
public const val DAY_OF_MONTH: Char = 'd'
public const val MONTH: Char = 'M'
public const val YEAR: Char = 'Y'
public const val ZONE: Char = 'z'
public const val ANY: Char = '*'
}
}
internal class GMTDateBuilder {
var seconds: Int? = null
var minutes: Int? = null
var hours: Int? = null
var dayOfMonth: Int? = null
lateinit var month: Month
var year: Int? = null
fun build(): GMTDate = GMTDate(seconds!!, minutes!!, hours!!, dayOfMonth!!, month, year!!)
}
/**
* Thrown when the date string doesn't the string pattern.
*/
public class InvalidDateStringException(
data: String,
at: Int,
pattern: String
) : IllegalStateException("Failed to parse date string: \"${data}\" at index $at. Pattern: \"$pattern\"")