mirror of
https://github.com/vitorpamplona/amethyst.git
synced 2025-11-10 07:47:16 +01:00
move MetaTagsParser to common module
This commit is contained in:
jiftechnify
@@ -0,0 +1,81 @@
|
||||
/**
|
||||
* Copyright (c) 2024 Vitor Pamplona
|
||||
*
|
||||
* Permission is hereby granted, free of charge, to any person obtaining a copy of
|
||||
* this software and associated documentation files (the "Software"), to deal in
|
||||
* the Software without restriction, including without limitation the rights to use,
|
||||
* copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
|
||||
* Software, and to permit persons to whom the Software is furnished to do so,
|
||||
* subject to the following conditions:
|
||||
*
|
||||
* The above copyright notice and this permission notice shall be included in all
|
||||
* copies or substantial portions of the Software.
|
||||
*
|
||||
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
||||
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
|
||||
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
|
||||
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
|
||||
* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
|
||||
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
|
||||
*/
|
||||
package com.vitorpamplona.amethyst.commons.preview
|
||||
|
||||
import org.junit.Assert.assertEquals
|
||||
import org.junit.Test
|
||||
|
||||
class MetaTagsParserTest {
|
||||
@Test
|
||||
fun testParse() {
|
||||
val input =
|
||||
"""<html>
|
||||
| <head>
|
||||
| <meta charset="utf-8">
|
||||
| <meta http-equiv="content-type" content="text/html; charset=utf-8">
|
||||
| <meta property="og:title" content=title>
|
||||
| <meta property="og:description" content='description'>
|
||||
| <meta property="og:image" content="https://example.com/img/foo.png">
|
||||
| <!-- edge cases -->
|
||||
| <meta
|
||||
| name="newline"
|
||||
| content="newline"
|
||||
| >
|
||||
| <meta name="space before gt" >
|
||||
| <meta name ="space before =">
|
||||
| <meta name= "space after =">
|
||||
| <META NAME="CAPITAL">
|
||||
| <meta name="character reference" content="<meta>">
|
||||
| <meta name="attr value with end of head doesn't harm" content="<head>bang!</head>">
|
||||
| <meta name="ignore tags with duplicated attr" name="dup">
|
||||
| </head>
|
||||
| <body>
|
||||
| <meta name="ignore meta tags in body">
|
||||
| </body>
|
||||
|</html>
|
||||
""".trimMargin()
|
||||
|
||||
val exp =
|
||||
listOf(
|
||||
listOf("charset" to "utf-8"),
|
||||
listOf("http-equiv" to "content-type", "content" to "text/html; charset=utf-8"),
|
||||
listOf("property" to "og:title", "content" to "title"),
|
||||
listOf("property" to "og:description", "content" to "description"),
|
||||
listOf("property" to "og:image", "content" to "https://example.com/img/foo.png"),
|
||||
listOf("name" to "newline", "content" to "newline"),
|
||||
listOf("name" to "space before gt"),
|
||||
listOf("name" to "space before ="),
|
||||
listOf("name" to "space after ="),
|
||||
listOf("name" to "CAPITAL"),
|
||||
listOf("name" to "character reference", "content" to "<meta>"),
|
||||
listOf("name" to "attr value with end of head doesn't harm", "content" to "<head>bang!</head>"),
|
||||
)
|
||||
|
||||
val metaTags = MetaTagsParser.parse(input).toList()
|
||||
println(metaTags)
|
||||
assertEquals(exp.size, metaTags.size)
|
||||
metaTags.zip(exp).forEach { (meta, expAttrs) ->
|
||||
expAttrs.forEach { (name, expValue) ->
|
||||
assertEquals(expValue, meta.attr(name))
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
@@ -0,0 +1,316 @@
|
||||
/**
|
||||
* Copyright (c) 2024 Vitor Pamplona
|
||||
*
|
||||
* Permission is hereby granted, free of charge, to any person obtaining a copy of
|
||||
* this software and associated documentation files (the "Software"), to deal in
|
||||
* the Software without restriction, including without limitation the rights to use,
|
||||
* copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
|
||||
* Software, and to permit persons to whom the Software is furnished to do so,
|
||||
* subject to the following conditions:
|
||||
*
|
||||
* The above copyright notice and this permission notice shall be included in all
|
||||
* copies or substantial portions of the Software.
|
||||
*
|
||||
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
||||
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
|
||||
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
|
||||
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
|
||||
* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
|
||||
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
|
||||
*/
|
||||
package com.vitorpamplona.amethyst.commons.preview
|
||||
|
||||
import kotlinx.collections.immutable.toImmutableMap
|
||||
import java.lang.StringBuilder
|
||||
|
||||
data class MetaTag(private val attrs: Map<String, String>) {
|
||||
/**
|
||||
* Returns a value of an attribute specified by its name (case insensitive), or empty string if it doesn't exist.
|
||||
*/
|
||||
fun attr(name: String): String = attrs[name.lowercase()] ?: ""
|
||||
}
|
||||
|
||||
object MetaTagsParser {
|
||||
private val NON_ATTR_NAME_CHARS = setOf(Char(0x0), '"', '\'', '>', '/')
|
||||
private val NON_UNQUOTED_ATTR_VALUE_CHARS = setOf('"', '\'', '=', '>', '<', '`')
|
||||
|
||||
/**
|
||||
* Lazily parse a partial HTML document and extract meta tags.
|
||||
*/
|
||||
fun parse(input: String): Sequence<MetaTag> =
|
||||
sequence {
|
||||
val s = TagScanner(input)
|
||||
while (!s.exhausted()) {
|
||||
val t = s.nextTag() ?: continue
|
||||
if (t.name == "/head") {
|
||||
break
|
||||
}
|
||||
if (t.name == "meta") {
|
||||
val attrs = parseAttrs(t.attrPart) ?: continue
|
||||
yield(MetaTag(attrs))
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
private data class RawTag(val name: String, val attrPart: String)
|
||||
|
||||
private class TagScanner(private val input: String) {
|
||||
var p = 0
|
||||
|
||||
fun exhausted(): Boolean = p >= input.length
|
||||
|
||||
private fun peek(): Char = input[p]
|
||||
|
||||
private fun consume(): Char {
|
||||
return input[p++]
|
||||
}
|
||||
|
||||
private fun consumeChar(c: Char): Boolean {
|
||||
if (this.peek() == c) {
|
||||
this.consume()
|
||||
return true
|
||||
}
|
||||
return false
|
||||
}
|
||||
|
||||
private fun skipSpaces() {
|
||||
while (!this.exhausted() && this.peek().isWhitespace()) {
|
||||
this.consume()
|
||||
}
|
||||
}
|
||||
|
||||
private fun skipUntil(c: Char) {
|
||||
while (!this.exhausted() && this.peek() != c) {
|
||||
this.consume()
|
||||
}
|
||||
}
|
||||
|
||||
private fun readWhile(pred: (Char) -> Boolean): String {
|
||||
val sb = StringBuilder()
|
||||
while (!this.exhausted() && pred(this.peek())) {
|
||||
sb.append(this.consume())
|
||||
}
|
||||
return sb.toString()
|
||||
}
|
||||
|
||||
fun nextTag(): RawTag? {
|
||||
skipUntil('<')
|
||||
consume()
|
||||
|
||||
// read tag name
|
||||
val name = StringBuilder()
|
||||
if (consumeChar('/')) {
|
||||
name.append('/')
|
||||
}
|
||||
val n = readWhile { !it.isWhitespace() && it != '>' }
|
||||
skipSpaces()
|
||||
|
||||
// read until end of tag
|
||||
val attrsPart = StringBuilder()
|
||||
var quote: Char? = null
|
||||
while (!exhausted()) {
|
||||
val c = consume()
|
||||
when {
|
||||
// `/>` out of quote -> end of tag
|
||||
quote == null && c == '/' && peek() == '>' -> {
|
||||
consume()
|
||||
break
|
||||
}
|
||||
// `>` out of quote -> end of tag
|
||||
quote == null && c == '>' -> {
|
||||
break
|
||||
}
|
||||
// entering quote
|
||||
quote == null && (c == '\'' || c == '"') -> {
|
||||
quote = c
|
||||
}
|
||||
// leaving quote
|
||||
quote != null && c == quote -> {
|
||||
quote = null
|
||||
}
|
||||
}
|
||||
attrsPart.append(c)
|
||||
}
|
||||
|
||||
if (!n.matches(Regex("""[0-9a-zA-Z]+"""))) {
|
||||
return null
|
||||
}
|
||||
return RawTag(name.append(n).toString().lowercase(), attrsPart.toString())
|
||||
}
|
||||
}
|
||||
|
||||
// map of HTML element attribute name to its value, with additional logics:
|
||||
// - attribute names are matched in a case-insensitive manner
|
||||
// - attribute names never duplicate
|
||||
// - commonly used character references in attribute values are resolved
|
||||
private class Attrs {
|
||||
companion object {
|
||||
val RE_CHAR_REF = Regex("""&(\w+)(;?)""")
|
||||
val BASE_CHAR_REFS =
|
||||
mapOf(
|
||||
"amp" to "&",
|
||||
"AMP" to "&",
|
||||
"quot" to "\"",
|
||||
"QUOT" to "\"",
|
||||
"lt" to "<",
|
||||
"LT" to "<",
|
||||
"gt" to ">",
|
||||
"GT" to ">",
|
||||
)
|
||||
val CHAR_REFS =
|
||||
mapOf(
|
||||
"apos" to "'",
|
||||
"equals" to "=",
|
||||
"grave" to "`",
|
||||
"DiacriticalGrave" to "`",
|
||||
)
|
||||
|
||||
fun replaceCharRefs(match: MatchResult): String {
|
||||
val bcr = BASE_CHAR_REFS[match.groupValues[1]]
|
||||
if (bcr != null) {
|
||||
return bcr
|
||||
}
|
||||
// non-base char refs must be terminated by ';'
|
||||
if (match.groupValues[2].isNotEmpty()) {
|
||||
val cr = CHAR_REFS[match.groupValues[1]]
|
||||
if (cr != null) {
|
||||
return cr
|
||||
}
|
||||
}
|
||||
return match.value
|
||||
}
|
||||
}
|
||||
|
||||
private val attrs = mutableMapOf<String, String>()
|
||||
|
||||
fun add(attr: Pair<String, String>) {
|
||||
val name = attr.first.lowercase()
|
||||
if (attrs.containsKey(name)) {
|
||||
throw IllegalArgumentException("duplicated attribute name: $name")
|
||||
}
|
||||
val value = attr.second.replace(RE_CHAR_REF, Companion::replaceCharRefs)
|
||||
attrs += Pair(name, value)
|
||||
}
|
||||
|
||||
fun freeze(): Map<String, String> = attrs.toImmutableMap()
|
||||
}
|
||||
|
||||
private enum class State {
|
||||
NAME,
|
||||
BEFORE_EQ,
|
||||
AFTER_EQ,
|
||||
VALUE,
|
||||
SPACE,
|
||||
}
|
||||
|
||||
private fun parseAttrs(input: String): Map<String, String>? {
|
||||
val attrs = Attrs()
|
||||
|
||||
var state = State.NAME
|
||||
var nameBegin = 0
|
||||
var nameEnd = 0
|
||||
var valueBegin = 0
|
||||
var valueQuote: Char? = null
|
||||
|
||||
input.forEachIndexed { i, c ->
|
||||
when (state) {
|
||||
State.NAME -> {
|
||||
when {
|
||||
c == '=' -> {
|
||||
nameEnd = i
|
||||
state = State.AFTER_EQ
|
||||
}
|
||||
|
||||
c.isWhitespace() -> {
|
||||
nameEnd = i
|
||||
state = State.BEFORE_EQ
|
||||
}
|
||||
|
||||
NON_ATTR_NAME_CHARS.contains(c) || c.isISOControl() || !c.isDefined() -> {
|
||||
return null
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
State.BEFORE_EQ -> {
|
||||
when {
|
||||
c == '=' -> {
|
||||
state = State.AFTER_EQ
|
||||
}
|
||||
|
||||
c.isWhitespace() -> {}
|
||||
else -> return null
|
||||
}
|
||||
}
|
||||
|
||||
State.AFTER_EQ -> {
|
||||
when {
|
||||
c.isWhitespace() -> {}
|
||||
c == '\'' || c == '"' -> {
|
||||
valueBegin = i + 1
|
||||
valueQuote = c
|
||||
state = State.VALUE
|
||||
}
|
||||
|
||||
else -> {
|
||||
valueBegin = i
|
||||
valueQuote = null
|
||||
state = State.VALUE
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
State.VALUE -> {
|
||||
var attr: Pair<String, String>? = null
|
||||
when {
|
||||
valueQuote != null -> {
|
||||
if (c == valueQuote) {
|
||||
attr =
|
||||
Pair(
|
||||
input.slice(nameBegin..<nameEnd),
|
||||
input.slice(valueBegin..<i),
|
||||
)
|
||||
}
|
||||
}
|
||||
|
||||
valueQuote == null -> {
|
||||
when {
|
||||
c.isWhitespace() -> {
|
||||
attr =
|
||||
Pair(
|
||||
input.slice(nameBegin..<nameEnd),
|
||||
input.slice(valueBegin..<i),
|
||||
)
|
||||
}
|
||||
|
||||
i == input.length - 1 -> {
|
||||
attr =
|
||||
Pair(
|
||||
input.slice(nameBegin..<nameEnd),
|
||||
input.slice(valueBegin..i),
|
||||
)
|
||||
}
|
||||
|
||||
NON_UNQUOTED_ATTR_VALUE_CHARS.contains(c) -> {
|
||||
return null
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
if (attr != null) {
|
||||
runCatching { attrs.add(attr) }.getOrNull() ?: return null
|
||||
state = State.SPACE
|
||||
}
|
||||
}
|
||||
|
||||
State.SPACE -> {
|
||||
if (!c.isWhitespace()) {
|
||||
nameBegin = i
|
||||
state = State.NAME
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
return attrs.freeze()
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user