Line helpers

Author: som-snytt

compiler/src/dotty/tools/dotc/reporting/MessageRendering.scala

@@ -13,13 +13,15 @@ import printing.SyntaxHighlighting
 import Diagnostic._
 import util.{ SourcePosition, NoSourcePosition }
 import util.Chars.{ LF, CR, FF, SU }
-import scala.annotation.switch
 
-import scala.collection.mutable
+import scala.annotation.switch
+import scala.collection.mutable, mutable.StringBuilder
+import scala.util.chaining.given
 
 trait MessageRendering {
   import Highlight.*
   import Offsets.*
+  import MessageRendering.*
 
   /** Remove ANSI coloring from `str`, useful for getting real length of
     * strings
@@ -204,12 +206,12 @@ trait MessageRendering {
           |${Blue("Explanation").show}
           |${Blue("===========").show}""".stripMargin
     )
-    sb.append(EOL).append(m.explanation)
+    sb.newLine(m.explanation)
     if (!m.explanation.endsWith(EOL)) sb.append(EOL)
     sb.toString
   }
 
-  private def appendFilterHelp(dia: Diagnostic, sb: mutable.StringBuilder): Unit =
+  private def appendFilterHelp(dia: Diagnostic, sb: StringBuilder): Unit =
     import dia._
     val hasId = msg.errorId.errorNumber >= 0
     val category = dia match {
@@ -221,22 +223,22 @@ trait MessageRendering {
     if (hasId || category.nonEmpty)
       sb.append(EOL).append("Matching filters for @nowarn or -Wconf:")
       if (hasId)
-        sb.append(EOL).append("  - id=E").append(msg.errorId.errorNumber)
-        sb.append(EOL).append("  - name=").append(msg.errorId.productPrefix.stripSuffix("ID"))
+        sb.newLine("  - id=E").append(msg.errorId.errorNumber)
+        sb.newLine("  - name=").append(msg.errorId.productPrefix.stripSuffix("ID"))
       if (category.nonEmpty)
-        sb.append(EOL).append("  - cat=").append(category)
+        sb.newLine("  - cat=").append(category)
 
   /** The whole message rendered from `msg` */
   def messageAndPos(dia: Diagnostic)(using Context): String = {
-    import dia._
+    import dia.{pos, msg, level}
     val pos1 = pos.nonInlined
     val inlineStack = inlinePosStack(pos).filter(_ != pos1)
     val maxLineNumber =
       if pos.exists then (pos1 :: inlineStack).map(_.endLine).max + 1
       else 0
     given Level = Level(level)
     given Offset = Offset(maxLineNumber.toString.length + 2)
-    val sb = mutable.StringBuilder()
+    val sb = StringBuilder()
     val posString = posStr(pos, msg, diagnosticLevel(dia))
     if (posString.nonEmpty) sb.append(posString).append(EOL)
     if (pos.exists) {
@@ -248,16 +250,16 @@ trait MessageRendering {
         sb.append((srcBefore ::: marker :: err :: srcAfter).mkString(EOL))
 
         if inlineStack.nonEmpty then
-          sb.append(EOL).append(newBox())
-          sb.append(EOL).append(offsetBox).append(i"Inline stack trace")
+          sb.newLine(newBox())
+          sb.newLine(offsetBox).append(i"Inline stack trace")
           for inlinedPos <- inlineStack if inlinedPos != pos1 do
-            sb.append(EOL).append(newBox(soft = true))
-            sb.append(EOL).append(offsetBox).append(i"This location contains code that was inlined from $pos")
+            sb.newLine(newBox(soft = true))
+            sb.newLine(offsetBox).append(i"This location contains code that was inlined from $pos")
             if inlinedPos.source.file.exists then
               val (srcBefore, srcAfter, _) = sourceLines(inlinedPos)
               val marker = positionMarker(inlinedPos)
-              sb.append(EOL).append((srcBefore ::: marker :: srcAfter).mkString(EOL))
-          sb.append(EOL).append(endBox)
+              sb.newLine((srcBefore ::: marker :: srcAfter).mkString(EOL))
+          sb.newLine(endBox)
       }
       else sb.append(msg.message)
     }
@@ -266,16 +268,16 @@ trait MessageRendering {
       appendFilterHelp(dia, sb)
 
     if Diagnostic.shouldExplain(dia) then
-      sb.append(EOL).append(newBox())
-      sb.append(EOL).append(offsetBox).append(" Explanation (enabled by `-explain`)")
-      sb.append(EOL).append(newBox(soft = true))
+      sb.newLine(newBox())
+      sb.newLine(offsetBox).append(" Explanation (enabled by `-explain`)")
+      sb.newLine(newBox(soft = true))
       dia.msg.explanation.split(raw"\R").foreach { line =>
-        sb.append(EOL).append(offsetBox).append(if line.isEmpty then "" else " ").append(line)
+        sb.newLine(offsetBox).append(if line.isEmpty then "" else " ").append(line)
       }
-      sb.append(EOL).append(endBox)
+      sb.newLine(endBox)
     else if dia.msg.canExplain then
-      sb.append(EOL).append(offsetBox)
-      sb.append(EOL).append(offsetBox).append(" longer explanation available when compiling with `-explain`")
+      sb.newLine(offsetBox)
+      sb.newLine(offsetBox).append(" longer explanation available when compiling with `-explain`")
 
     sb.toString
   }
@@ -299,6 +301,10 @@ trait MessageRendering {
     }
 
 }
+private object MessageRendering:
+  extension (sb: StringBuilder)
+    def newLine(s: String): sb.type = sb.tap(_.append(EOL).append(s))
+    def mkLines: String = sb.mkString(EOL)
 
 private object Highlight {
   opaque type Level = Int

compiler/src/dotty/tools/dotc/util/SourceFile.scala

@@ -198,11 +198,9 @@ class SourceFile(val file: AbstractFile, computeContent: => Array[Char]) extends
   def lineContent(offset: Int): String =
     content.slice(startOfLine(offset), nextLine(offset)).mkString
 
-  /** The column corresponding to `offset`, starting at 0 */
-  def column(offset: Int): Int = {
-    var idx = startOfLine(offset)
-    offset - idx
-  }
+  /** The column (index into the line) corresponding to `offset`, starting at 0 */
+  def column(offset: Int): Int =
+    offset - startOfLine(offset)
 
   /** The padding of the column corresponding to `offset`, includes tabs */
   def startColumnPadding(offset: Int): String = {