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https://github.com/vitorpamplona/amethyst.git
synced 2025-04-10 12:59:51 +02:00
optimize HTML charset detection
This commit is contained in:
jiftechnify
parent
3434c31487
commit
d0aa7430ca
@ -22,6 +22,7 @@ package com.vitorpamplona.amethyst.service.previews
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import com.vitorpamplona.amethyst.service.HttpClientManager
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import com.vitorpamplona.amethyst.service.checkNotInMainThread
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import kotlinx.collections.immutable.toImmutableMap
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import kotlinx.coroutines.Dispatchers
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import kotlinx.coroutines.withContext
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import okhttp3.MediaType
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@ -34,15 +35,14 @@ import okio.Options
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import org.jsoup.Jsoup
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import org.jsoup.nodes.Document
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import java.io.ByteArrayInputStream
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import java.io.IOException
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import java.nio.charset.Charset
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private const val ELEMENT_TAG_META = "meta"
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private const val ATTRIBUTE_VALUE_CHARSET = "charset"
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private const val ATTRIBUTE_VALUE_HTTP_EQUIV = "http-equiv"
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private const val ATTRIBUTE_VALUE_PROPERTY = "property"
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private const val ATTRIBUTE_VALUE_NAME = "name"
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private const val ATTRIBUTE_VALUE_ITEMPROP = "itemprop"
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private const val ATTRIBUTE_VALUE_CHARSET = "charset"
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private const val ATTRIBUTE_VALUE_HTTP_EQUIV = "http-equiv"
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// for <meta itemprop=... to get title
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private val META_X_TITLE =
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@ -104,9 +104,9 @@ suspend fun getDocument(
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checkNotInMainThread()
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if (it.isSuccessful) {
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val mimeType =
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it.headers.get("Content-Type")?.toMediaType()
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it.headers["Content-Type"]?.toMediaType()
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?: throw IllegalArgumentException(
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"Website returned unknown mimetype: ${it.headers.get("Content-Type")}",
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"Website returned unknown mimetype: ${it.headers["Content-Type"]}",
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)
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if (mimeType.type == "text" && mimeType.subtype == "html") {
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parseHtml(url, it.body, mimeType)
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@ -142,11 +142,12 @@ suspend fun parseHtml(
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// if sniffing was failed, detect charset from content
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val bodyBytes = source.readByteArray()
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val charset = detectCharset(bodyBytes, url)
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val charset = detectCharset(bodyBytes)
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val doc = Jsoup.parse(ByteArrayInputStream(bodyBytes), charset.name(), url)
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return@withContext parseUrlInfo(url, doc, type)
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}
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// taken from okhttp
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private val UNICODE_BOMS =
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Options.of(
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// UTF-8
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@ -161,7 +162,6 @@ private val UNICODE_BOMS =
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"ffff0000".decodeHex(),
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)
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@Throws(IOException::class)
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private fun BufferedSource.readBomAsCharset(): Charset? {
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return when (select(UNICODE_BOMS)) {
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0 -> Charsets.UTF_8
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@ -174,16 +174,13 @@ private fun BufferedSource.readBomAsCharset(): Charset? {
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}
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}
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private val RE_CONTENT_TYPE_CHARSET = Regex("""charset\s*=\s*([^;]+)""")
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private val RE_CONTENT_TYPE_CHARSET = Regex("""charset=([^;]+)""")
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private fun detectCharset(
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bodyBytes: ByteArray,
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url: String,
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): Charset {
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// tentatively decode response body as UTF-8
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val tentativeDoc = Jsoup.parse(ByteArrayInputStream(bodyBytes), "utf-8", url)
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tentativeDoc.getElementsByTag(ELEMENT_TAG_META).forEach { meta ->
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private fun detectCharset(bodyBytes: ByteArray): Charset {
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// try to detect charset from meta tags parsed from first 1024 bytes of body
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val firstPart = String(bodyBytes, 0, 1024, Charset.forName("utf-8"))
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val metaTags = runCatching { MetaTagsParser.parse(firstPart) }.getOrDefault(emptySequence())
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metaTags.forEach { meta ->
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val charsetAttr = meta.attr(ATTRIBUTE_VALUE_CHARSET)
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if (charsetAttr.isNotEmpty()) {
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runCatching { Charset.forName(charsetAttr) }.getOrNull()?.let {
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@ -199,6 +196,7 @@ private fun detectCharset(
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}
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}
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}
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// defaults to UTF-8
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return Charset.forName("utf-8")
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}
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@ -271,3 +269,156 @@ private fun parseUrlInfo(
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}
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return UrlInfoItem(url, title, description, image, type)
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}
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private class MetaTag(private val attrs: Map<String, String>) {
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fun attr(name: String): String = attrs[name.lowercase()] ?: ""
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}
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// map of HTML element attribute name to its value, with some guarantees:
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// - attribute names are compared in a case-insensitive manner
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// - attribute names never duplicate
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private class Attrs {
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private val attrs = mutableMapOf<String, String>()
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fun add(attr: Pair<String, String>) {
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val name = attr.first.lowercase()
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if (attrs.containsKey(name)) {
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throw IllegalArgumentException("duplicated attribute name: $name")
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}
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attrs += Pair(name, attr.second)
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}
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fun freeze(): Map<String, String> = attrs.toImmutableMap()
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}
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// parser for parsing a partial HTML document into meta tags
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private object MetaTagsParser {
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private val RE_META = Regex("""<meta\s+(.+?)\s*>""", setOf(RegexOption.IGNORE_CASE, RegexOption.DOT_MATCHES_ALL))
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private val NON_ATTR_NAME_CHARS = setOf(Char(0x0), '"', '\'', '>', '/')
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private val NON_UNQUOTED_ATTR_VALUE_CHARS = setOf('"', '\'', '=', '>', '<', '`')
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fun parse(input: String): Sequence<MetaTag> =
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RE_META.findAll(input).map {
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MetaTag(parseAttrs(it.groupValues[1]))
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}
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private enum class State {
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NAME,
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BEFORE_EQ,
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AFTER_EQ,
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VALUE,
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SPACE,
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}
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private fun parseAttrs(input: String): Map<String, String> {
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val attrs = Attrs()
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var state = State.NAME
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var nameBegin = 0
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var nameEnd = 0
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var valueBegin = 0
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var valueQuote: Char? = null
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input.forEachIndexed { i, c ->
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when (state) {
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State.NAME -> {
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when {
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c == '=' -> {
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nameEnd = i
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state = State.AFTER_EQ
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}
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c.isWhitespace() -> {
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nameEnd = i
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state = State.BEFORE_EQ
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}
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NON_ATTR_NAME_CHARS.contains(c) || c.isISOControl() || !c.isDefined() -> {
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throw IllegalArgumentException("meta has invalid attributes part")
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}
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}
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}
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State.BEFORE_EQ -> {
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when {
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c == '=' -> {
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state = State.AFTER_EQ
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}
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c.isWhitespace() -> {}
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else -> throw IllegalArgumentException("meta has invalid attributes part")
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}
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}
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State.AFTER_EQ -> {
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when {
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c.isWhitespace() -> {}
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c == '\'' || c == '"' -> {
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valueBegin = i + 1
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valueQuote = c
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state = State.VALUE
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}
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else -> {
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valueBegin = i
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valueQuote = null
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state = State.VALUE
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}
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}
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}
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State.VALUE -> {
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var attr: Pair<String, String>? = null
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when {
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valueQuote != null -> {
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if (c == valueQuote) {
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attr =
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Pair(
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input.slice(nameBegin until nameEnd),
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input.slice(valueBegin until i),
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)
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}
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}
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valueQuote == null -> {
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when {
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c.isWhitespace() -> {
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attr =
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Pair(
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input.slice(nameBegin until nameEnd),
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input.slice(valueBegin until i),
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)
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}
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i == input.length - 1 -> {
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attr =
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Pair(
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input.slice(nameBegin until nameEnd),
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input.slice(valueBegin..i),
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)
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}
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NON_UNQUOTED_ATTR_VALUE_CHARS.contains(c) -> {
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throw IllegalArgumentException("meta has invalid attributes part")
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}
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}
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}
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}
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if (attr != null) {
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attrs.add(attr)
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state = State.SPACE
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}
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}
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State.SPACE -> {
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if (!c.isWhitespace()) {
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nameBegin = i
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state = State.NAME
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}
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}
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}
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}
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return attrs.freeze()
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}
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}
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