bugfix: Remove usage of some internal scalameta methods

These methods are not checked by mima, so it's best to remove any usage of it.

There is still some internal methods, which we might want to move out from internal package in scalameta in the future, but theys are much less problematic

cli/src/main/scala/mdoc/internal/cli/CliEnrichments.scala

@@ -1,20 +1,20 @@
 package mdoc.internal.cli
 
+import coursierapi.Dependency
+
+import java.io.PrintStream
 import java.nio.charset.StandardCharsets
 import java.nio.file.Files
 import java.nio.file.Paths
 import java.nio.file.StandardCopyOption
 import scala.meta.Input
 import scala.meta.Position
+import scala.meta.internal.io.FileIO
+import scala.meta.internal.io.PathIO
 import scala.meta.io.AbsolutePath
 import scala.meta.io.RelativePath
-import scala.meta.internal.io.PathIO
-import scala.util.control.NonFatal
-import coursierapi.Dependency
-import scala.meta.internal.io.FileIO
-import scala.meta.internal.inputs._
-import java.io.PrintStream
 import scala.util.Try
+import scala.util.control.NonFatal
 
 trait CliEnrichments {
   implicit class XtensionInputMdoc(input: Input) {
@@ -26,6 +26,12 @@ trait CliEnrichments {
           Try(AbsolutePath(Paths.get(v.path)).filename).getOrElse(v.path)
         case _ => input.syntax
       }
+    def syntax: String = input match {
+      case Input.None => "<none>"
+      case Input.File(path, _) => path.toString
+      case Input.VirtualFile(path, _) => path
+      case _ => "<input>"
+    }
     def relativeFilename(sourceroot: AbsolutePath): RelativePath =
       input match {
         case s: Input.Slice =>
@@ -64,7 +70,17 @@ trait CliEnrichments {
     }
   }
 
-  implicit class XtensionPositionMdoc(pos: Position) {
+  implicit class XtensionPositionMdoc(pos: Position) extends InternalInput(pos.input) {
+    def lineContent: String = {
+      val input = pos.input
+      val start = lineToOffset(pos.startLine)
+      val notEof = start < input.chars.length
+      val end = if (notEof) lineToOffset(pos.startLine + 1) else start
+      new String(input.chars, start, end - start).stripLineEnd
+    }
+    def lineCaret: String = {
+      " " * pos.startColumn + "^"
+    }
     def addStart(offset: Int): Position =
       pos match {
         case Position.Range(i, start, end) =>

cli/src/main/scala/mdoc/internal/cli/InternalInput.scala

@@ -0,0 +1,62 @@
+package mdoc.internal.cli
+
+import scala.collection.mutable
+import scala.meta.inputs._
+import scala.meta.Dialect
+import scala.meta.tokens.Tokens
+import scala.meta.internal.tokenizers.Compat
+
+// Copied over from scalameta/scalameta
+abstract class InternalInput(input: Input) {
+
+  // NOTE: It's regrettable that we need to taint the pure abstraction of Input.
+  // However, as #334 shows, we just can't redo offset -> line conversions over and over again.
+  // This means that we gotta cache, and this instance is really the only place versatile enough.
+  private lazy val cachedLineIndices: Array[Int] = {
+    val chars = input.chars
+    val buf = new mutable.ArrayBuffer[Int]
+    buf += 0
+    var i = 0
+    while (i < chars.length) {
+      if (chars(i) == '\n') buf += (i + 1)
+      i += 1
+    }
+    if (buf.last != chars.length) buf += chars.length // sentinel value used for binary search
+    buf.toArray
+  }
+
+  def lineToOffset(line: Int): Int = {
+    // NOTE: The length-1 part is not a typo, it's to accommodate the sentinel value.
+    if (!(0 <= line && line <= cachedLineIndices.length - 1)) {
+      val message =
+        s"$line is not a valid line number, allowed [0..${cachedLineIndices.length - 1}]"
+      throw new IllegalArgumentException(message)
+    }
+    cachedLineIndices(line)
+  }
+
+  def offsetToLine(offset: Int): Int = {
+    val chars = input.chars
+    val a = cachedLineIndices
+    // NOTE: We allow chars.length, because it's a valid value for an offset.
+    if (!(0 <= offset && offset <= chars.length)) {
+      val message = s"$offset is not a valid offset, allowed [0..${chars.length}]"
+      throw new IllegalArgumentException(message)
+    }
+    // NOTE: chars.length requires a really ugly special case.
+    // If the file doesn't end with \n, then it's simply last_line:last_col+1.
+    // But if the file does end with \n, then it's last_line+1:0.
+    if (offset == chars.length && (0 < chars.length && chars(offset - 1) == '\n')) {
+      return a.length - 1
+    }
+    var lo = 0
+    var hi = a.length - 1
+    while (hi - lo > 1) {
+      val mid = (hi + lo) / 2
+      if (offset < a(mid)) hi = mid
+      else if (a(mid) == offset) return mid
+      else /* if (a(mid) < offset */ lo = mid
+    }
+    lo
+  }
+}

mdoc/src/main/scala-2/mdoc/internal/markdown/MarkdownCompiler.scala

@@ -29,7 +29,6 @@ import scala.tools.nsc.io.VirtualDirectory
 import scala.annotation.implicitNotFound
 import mdoc.internal.CompatClassloader
 import mdoc.internal.worksheets.Compat._
-import scala.meta.internal.inputs._
 
 class MarkdownCompiler(
     classpath: String,

mdoc/src/main/scala-3/mdoc/internal/markdown/MarkdownCompiler.scala

@@ -27,7 +27,6 @@ import scala.meta.Classpath
 import scala.meta.AbsolutePath
 import scala.meta.inputs.Input
 import scala.meta.inputs.Position
-import scala.meta.internal.inputs.XtensionInputSyntaxStructure
 
 import dotty.tools.dotc.interactive.InteractiveDriver
 import dotty.tools.dotc.interactive.Interactive

mdoc/src/main/scala/mdoc/internal/markdown/Markdown.scala

@@ -1,6 +1,5 @@
 package mdoc.internal.markdown
 
-import scala.meta.internal.inputs._
 import com.vladsch.flexmark.ext.yaml.front.matter.YamlFrontMatterBlock
 import com.vladsch.flexmark.formatter.Formatter
 import com.vladsch.flexmark.html.HtmlRenderer

mdoc/src/main/scala/mdoc/internal/pos/PositionSyntax.scala

@@ -16,7 +16,6 @@ import scala.meta.internal.io.PathIO
 import scala.util.control.NonFatal
 import coursierapi.Dependency
 import scala.meta.internal.io.FileIO
-import scala.meta.internal.inputs._
 
 object PositionSyntax extends CliEnrichments with CollectionEnrichments {
   implicit class XtensionRangePositionMdoc(pos: RangePosition) {