Use handwritten tokenizer for SMAP parsing

SMAP parsing is a hot spot. Handwritten tokenization significantly boosts the performance. See ^KT-61527
2023-08-23 19:22:51 +02:00
parent 4eac193463
commit f11c96cba2
1 changed files with 38 additions and 1 deletions
@@ -35,9 +35,46 @@ object SMAPParser {
    fun parseOrNull(mappingInfo: String): SMAP? =
        parseStratum(mappingInfo, KOTLIN_STRATA_NAME, parseStratum(mappingInfo, KOTLIN_DEBUG_STRATA_NAME, null))

+    private class SMAPTokenizer(private val text: String, private val headerString: String) : Iterator<String> {
+
+        private var pos = 0
+        private var currentLine: String? = null
+
+        init {
+            advance()
+            while (currentLine != null && currentLine != headerString) {
+                advance()
+            }
+            if (currentLine == headerString) {
+                advance()
+            }
+        }
+
+        private fun advance() {
+            if (pos >= text.length) {
+                currentLine = null
+                return
+            }
+            val fromPos = pos
+            while (pos < text.length && text[pos] != '\n' && text[pos] != '\r') pos++
+            currentLine = text.substring(fromPos, pos)
+            pos++
+        }
+
+        override fun hasNext(): Boolean {
+            return currentLine != null
+        }
+
+        override fun next(): String {
+            val res = currentLine ?: throw NoSuchElementException()
+            advance()
+            return res
+        }
+    }
+
    private fun parseStratum(mappingInfo: String, stratum: String, callSites: SMAP?): SMAP? {
        val fileMappings = linkedMapOf<Int, FileMapping>()
-        val iterator = mappingInfo.lineSequence().dropWhile { it != "${SMAP.STRATA_SECTION} $stratum" }.drop(1).iterator()
+        val iterator = SMAPTokenizer(mappingInfo, "${SMAP.STRATA_SECTION} $stratum")
        // JSR-045 allows the line section to come before the file section, but we don't generate SMAPs like this.
        if (!iterator.hasNext() || iterator.next() != SMAP.FILE_SECTION) return null