refactor: tidy parser file layout and inline redundant NFC wrapper

kuri/src/commonMain/kotlin/org/dexpace/kuri/idna/Idna.kt

@@ -63,7 +63,8 @@ internal object Idna {
         beStrict: Boolean = false,
     ): ParseResult<String> {
         val mapped = mapAll(domain) ?: return idnaError(domain)
-        val labels = splitLabels(normalizeNfc(mapped))
+        // UTS-46 step 3: canonical NFC normalization (UAX #15), applied post-mapping, pre-label-split.
+        val labels = splitLabels(Normalizer.nfc(mapped))
         return processLabels(labels, domain).map { it.joinToString(LABEL_SEPARATOR) }
     }
 
@@ -103,13 +104,11 @@ internal object Idna {
      */
     internal fun domainToUnicode(domain: String): String {
         val mapped = mapAll(domain) ?: domain
-        val labels = splitLabels(normalizeNfc(mapped))
+        // UTS-46 step 3: canonical NFC normalization (UAX #15), applied post-mapping, pre-label-split.
+        val labels = splitLabels(Normalizer.nfc(mapped))
         return labels.joinToString(LABEL_SEPARATOR) { decodeLabelForDisplay(it) }
     }
 
-    /** UTS-46 step 3: canonical NFC normalization (UAX #15), applied post-mapping, pre-label-split. */
-    private fun normalizeNfc(s: String): String = Normalizer.nfc(s)
-
     /**
      * Applies the UTS-46 mapping step to every code point of [domain], returning the mapped text or
      * `null` on the first disallowed code point (the caller turns `null` into a fatal error).
@@ -200,7 +199,7 @@ internal object Idna {
      * Re-validates a freshly Punycode-decoded A-label (UTS-46 V1 / P4): the decoded U-label must be
      * non-empty, must carry a non-ASCII code point (an all-ASCII result should never have been
      * ACE-encoded, whatwg/url#760), must already be in NFC (V1), and must not itself begin with the
-     * ACE prefix (a double-encoded label, whatwg/url#803). The top-level NFC pass ([normalizeNfc])
+     * ACE prefix (a double-encoded label, whatwg/url#803). The top-level NFC pass ([Normalizer.nfc])
      * runs before Punycode decoding, so this is the only point the decoded label's NFC form is checked.
      */
     internal fun isValidDecodedALabel(decoded: String): Boolean =

kuri/src/commonMain/kotlin/org/dexpace/kuri/parser/UrlParserAuthority.kt

@@ -15,9 +15,6 @@ import org.dexpace.kuri.percent.PercentEncodeSets
 import org.dexpace.kuri.scheme.Scheme
 import org.dexpace.kuri.text.isAsciiDigit
 
-/** The canonical `file` scheme, special-cased by the file sub-machine (§8.3). */
-private const val FILE_SCHEME: String = "file"
-
 /** WHATWG `localhost`, mapped to the empty host in the FILE_HOST state ([PARSE-37]). */
 private const val LOCALHOST: String = "localhost"
 

kuri/src/commonMain/kotlin/org/dexpace/kuri/parser/UrlParserHelpers.kt

@@ -2,13 +2,23 @@
  * Copyright (c) 2026 dexpace and Omar Aljarrah
  * SPDX-License-Identifier: MIT
  */
+
+// The flat bag of profile-agnostic §8.3 path/authority/drive predicates the Url state machine keys
+// off; grouping them beside their consumers keeps one definition per rule (hence the per-file
+// function count legitimately exceeds detekt's heuristic).
+@file:Suppress("TooManyFunctions")
+
 package org.dexpace.kuri.parser
 
 import org.dexpace.kuri.percent.PercentCodec
 import org.dexpace.kuri.percent.PercentEncodeSets
+import org.dexpace.kuri.text.isAsciiAlpha
 
-/** The canonical scheme name whose state machine owns the Windows-drive-letter quirks. */
-private const val FILE_SCHEME: String = "file"
+/** The canonical `file` scheme, special-cased throughout the §8.3 `Url` state machine. */
+internal const val FILE_SCHEME: String = "file"
+
+/** The code points that may terminate a Windows drive letter prefix (`/`, `\`, `?`, `#`). */
+private const val WINDOWS_DRIVE_TERMINATORS: String = "/\\?#"
 
 /**
  * True when [ch] is one of the three universal authority/path terminators `/`, `?`, `#`
@@ -105,3 +115,26 @@ internal fun cloneBasePath(base: ParsedComponents?): MutableList<String> {
     val segments = (base?.path as? UrlPath.Segments)?.segments ?: emptyList()
     return segments.toMutableList()
 }
+
+/**
+ * True when [value] *is* a Windows drive letter: exactly an ASCII alpha followed by `:`
+ * or `|` (SPEC §9.4 [PATH-14]).
+ */
+internal fun isWindowsDriveLetter(value: String): Boolean =
+    value.length == 2 && value[0].isAsciiAlpha() && (value[1] == ':' || value[1] == '|')
+
+/**
+ * True when [value] is a *normalized* Windows drive letter: an ASCII alpha followed by `:`
+ * (SPEC §9.4 [PATH-14]).
+ */
+internal fun isNormalizedWindowsDrive(value: String): Boolean =
+    value.length == 2 && value[0].isAsciiAlpha() && value[1] == ':'
+
+/**
+ * True when [value] *starts with* a Windows drive letter (SPEC §9.4 [PATH-14]): a drive
+ * letter that is either the whole string or immediately followed by `/`, `\`, `?`, or `#`.
+ */
+internal fun startsWithWindowsDrive(value: String): Boolean {
+    val hasDrive = value.length >= 2 && value[0].isAsciiAlpha() && (value[1] == ':' || value[1] == '|')
+    return hasDrive && (value.length == 2 || value[2] in WINDOWS_DRIVE_TERMINATORS)
+}

kuri/src/commonMain/kotlin/org/dexpace/kuri/parser/UrlParserStates.kt

@@ -13,9 +13,6 @@ import org.dexpace.kuri.scheme.isSchemeContinuationChar
 import org.dexpace.kuri.text.asciiLowercased
 import org.dexpace.kuri.text.isAsciiAlpha
 
-/** The canonical `file` scheme, special-cased throughout the §8 state machine. */
-private const val FILE_SCHEME: String = "file"
-
 /**
  * The routing, scheme, relative-resolution, path, query, and opaque-path states of the §8.3
  * `Url`-profile state machine (WHATWG basic URL parser).