From d4e28b87234a5374a2f6139c58e16c9a014a5b1d Mon Sep 17 00:00:00 2001
From: soywiz <soywiz@gmail.com>
Date: Mon, 11 Mar 2019 01:34:14 +0100
Subject: [PATCH] Optimize StrReader and Xml parsing

---
 .../com/soywiz/korio/serialization/xml/Xml.kt | 44 +++++++++++--------
 .../kotlin/com/soywiz/korio/util/StrReader.kt | 10 ++++-
 .../serialization/xml/XmlEntitiesTest.kt      | 21 +++++++++
 3 files changed, 54 insertions(+), 21 deletions(-)
 create mode 100644 korio/src/commonTest/kotlin/com/soywiz/korio/serialization/xml/XmlEntitiesTest.kt

diff --git a/korio/src/commonMain/kotlin/com/soywiz/korio/serialization/xml/Xml.kt b/korio/src/commonMain/kotlin/com/soywiz/korio/serialization/xml/Xml.kt
index e6356062..2ad5b876 100644
--- a/korio/src/commonMain/kotlin/com/soywiz/korio/serialization/xml/Xml.kt
+++ b/korio/src/commonMain/kotlin/com/soywiz/korio/serialization/xml/Xml.kt
@@ -168,17 +168,19 @@ data class Xml(
 		fun decode(r: StrReader): String = buildString {
 			while (!r.eof) {
 				@Suppress("LiftReturnOrAssignment") // Performance?
-				when (val c = r.readChar()) {
-					'&' -> {
-						val value = r.readUntilIncluded(';') ?: ""
-						val full = "&$value"
-						append(when {
-							value.startsWith('#') -> "${value.substring(1, value.length - 1).toInt().toChar()}"
-							entityToChar.contains(full) -> "${entityToChar[full]}"
-							else -> full
-						})
-					}
-					else -> append(c)
+				val plain = r.readUntil('&')
+				if (plain != null) {
+					append(plain)
+				}
+				if (r.eof) break
+
+				r.skipExpect('&')
+				val value = r.readUntilIncluded(';') ?: ""
+				val full = "&$value"
+				when {
+					value.startsWith('#') -> append(value.substring(1, value.length - 1).toInt().toChar())
+					entityToChar.contains(full) -> append(entityToChar[full])
+					else -> append(full)
 				}
 			}
 		}
@@ -200,13 +202,14 @@ data class Xml(
 				if (r.eof) break
 
 				r.skipExpect('<')
+				var res: Element? = null
 				when {
 					r.tryExpect("![CDATA[") -> {
 						val start = r.pos
 						while (!r.eof) {
 							val end = r.pos
 							if (r.tryExpect("]]>")) {
-								yield(Element.Text(r.createRange(start, end).text))
+								res = Element.Text(r.createRange(start, end).text)
 								break
 							}
 							r.readChar()
@@ -217,7 +220,7 @@ data class Xml(
 						while (!r.eof) {
 							val end = r.pos
 							if (r.tryExpect("-->")) {
-								yield(Element.CommentTag(r.createRange(start, end).text))
+								res = Element.CommentTag(r.createRange(start, end).text)
 								break
 							}
 							r.readChar()
@@ -253,15 +256,18 @@ data class Xml(
 						val openclose = r.tryExpect('/')
 						val processingInstructionEnd = r.tryExpect('?')
 						r.skipExpect('>')
-						when {
-							processingInstruction || processingEntityOrDocType ->
-								yield(Element.ProcessingInstructionTag(name, attributes))
-							openclose -> yield(Element.OpenCloseTag(name, attributes))
-							close -> yield(Element.CloseTag(name))
-							else -> yield(Element.OpenTag(name, attributes))
+						res = when {
+							processingInstruction || processingEntityOrDocType -> Element.ProcessingInstructionTag(name, attributes)
+							openclose -> Element.OpenCloseTag(name, attributes)
+							close -> Element.CloseTag(name)
+							else -> Element.OpenTag(name, attributes)
 						}
 					}
 				}
+
+				if (res != null) {
+					yield(res)
+				}
 			}
 		}
 
diff --git a/korio/src/commonMain/kotlin/com/soywiz/korio/util/StrReader.kt b/korio/src/commonMain/kotlin/com/soywiz/korio/util/StrReader.kt
index 89521e37..9c138306 100644
--- a/korio/src/commonMain/kotlin/com/soywiz/korio/util/StrReader.kt
+++ b/korio/src/commonMain/kotlin/com/soywiz/korio/util/StrReader.kt
@@ -49,8 +49,14 @@ class StrReader(val str: String, val file: String = "file", var pos: Int = 0) {
 	fun peek(): Char = if (hasMore) this.str[this.pos] else '\u0000'
 	fun peekChar(): Char = if (hasMore) this.str[this.pos] else '\u0000'
 	fun read(count: Int): String = this.peek(count).apply { skip(count) }
-	fun skipUntil(char: Char) = run { while (hasMore && this.peekChar() != char) this.readChar() }
-	fun skipUntilIncluded(char: Char) = run { while (hasMore && this.readChar() != char) Unit }
+	fun skipUntil(char: Char) {
+		val skipPos = this.str.indexOf(char, pos)
+		pos = (if (skipPos >= 0) skipPos else length)
+	}
+	fun skipUntilIncluded(char: Char) {
+		skipUntil(char)
+		if (!eof && peekChar() == char) skip(1)
+	}
 	//inline fun skipWhile(check: (Char) -> Boolean) = run { while (check(this.peekChar())) this.skip(1) }
 	inline fun skipWhile(filter: (Char) -> Boolean) = run { while (hasMore && filter(this.peekChar())) this.readChar() }
 
diff --git a/korio/src/commonTest/kotlin/com/soywiz/korio/serialization/xml/XmlEntitiesTest.kt b/korio/src/commonTest/kotlin/com/soywiz/korio/serialization/xml/XmlEntitiesTest.kt
new file mode 100644
index 00000000..605258a7
--- /dev/null
+++ b/korio/src/commonTest/kotlin/com/soywiz/korio/serialization/xml/XmlEntitiesTest.kt
@@ -0,0 +1,21 @@
+package com.soywiz.korio.serialization.xml
+
+import kotlin.test.*
+
+class XmlEntitiesTest {
+	@Test
+	fun testDecode() {
+		assertEquals("hello", Xml.Entities.decode("hello"))
+		assertEquals("\"", Xml.Entities.decode("&quot;"))
+		assertEquals("hello\"world", Xml.Entities.decode("hello&quot;world"))
+		assertEquals("hello\"world\"", Xml.Entities.decode("hello&quot;world&quot;"))
+	}
+
+	@Test
+	fun testEncode() {
+		assertEquals("hello", Xml.Entities.encode("hello"))
+		assertEquals("&quot;", Xml.Entities.encode("\""))
+		assertEquals("hello&quot;world", Xml.Entities.encode("hello\"world"))
+		assertEquals("hello&quot;world&quot;", Xml.Entities.encode("hello\"world\""))
+	}
+}