Backport 4.1/various error related bugs (#179)

* Fixed overwide carets in trivial errors, hints from adjusting unexpected size to 0, and hints from getting reborn during an iterative combinator

* version bump to 4.1.8

README.md

@@ -8,7 +8,7 @@ Parsley is a fast and modern parser combinator library for Scala based loosely o
 Parsley is distributed on Maven Central, and can be added to your project via:
 
 ```scala
-libraryDependencies += "com.github.j-mie6" %% "parsley" % "4.1.7"
+libraryDependencies += "com.github.j-mie6" %% "parsley" % "4.1.8"
 ```
 
 Documentation can be found [**here**](https://javadoc.io/doc/com.github.j-mie6/parsley_2.13/latest/index.html)

parsley/shared/src/main/scala/parsley/internal/errors/ParseError.scala

@@ -32,7 +32,7 @@ private [internal] case class TrivialError(offset: Int, line: Int, col: Int,
             builder.unexpected(unexpectedTok.toOption.map(_._1)),
             builder.expected(builder.combineExpectedItems(expecteds.map(_.formatExpect))),
             builder.combineMessages(reasons.map(builder.reason(_)).toSeq),
-            builder.lineInfo(line, beforeLines, afterLines, caret, caretSize))
+            builder.lineInfo(line, beforeLines, afterLines, caret, math.min(caretSize, line.length-caret)))
     }
 }
 private [internal] case class FancyError(offset: Int, line: Int, col: Int, msgs: List[String], caretWidth: Int, lexicalError: Boolean) extends ParseError {

parsley/shared/src/main/scala/parsley/internal/machine/Context.scala

@@ -110,7 +110,7 @@ private [parsley] final class Context(private [machine] var instrs: Array[Instr]
 
     private [machine] def updateCheckOffsetAndHints() = {
         this.checkStack.offset = this.offset
-        this.hintsValidOffset = this.offset
+        //this.hintsValidOffset = this.offset // FIXME: verify that this is ok to remove, it seems stupid now that I think about it
     }
 
     // $COVERAGE-OFF$

parsley/shared/src/main/scala/parsley/internal/machine/errors/DefuncBuilders.scala

@@ -179,19 +179,19 @@ private [errors] final class HintCollector(hints: mutable.Set[ExpectItem]) {
     /** Creates a new collector that starts empty */
     def this() = this(mutable.Set.empty)
 
-    private var width = 0
+    private var width = Option.empty[Int]
 
     /** Adds a new hint into the collector. */
     def +=(hint: ExpectItem): Unit = this.hints += hint
     /** Adds several hints into the collector. */
     def ++=(hints: Iterable[ExpectItem]): Unit = this.hints ++= hints
 
     /** Gets the width of the unexpected token that may have accompanied the original hints */
-    def unexpectWidth: Int = width
+    def unexpectWidth: Option[Int] = width
     /** Updates the width of the unexpected token that may have accompanied these hints: this
       * can only get wider.
       */
-    def updateWidth(sz: Int): Unit = width = Math.max(width, sz)
+    def updateWidth(sz: Int): Unit = width = Some(Math.max(width.getOrElse(0), sz))
 
     /** Generates an immutable snapshot of this collector */
     def mkSet: Set[ExpectItem] = this.hints.toSet

parsley/shared/src/main/scala/parsley/internal/machine/errors/DefuncError.scala

@@ -351,8 +351,7 @@ private [errors] final class WithHints private [errors] (val err: TrivialDefuncE
     override def makeTrivial(builder: TrivialErrorBuilder): Unit = {
         err.makeTrivial(builder)
         builder.whenAcceptingExpected {
-            val size = hints.updateExpectedsAndGetSize(builder)
-            builder.updateUnexpected(size)
+            for (size <- hints.updateExpectedsAndGetSize(builder)) builder.updateUnexpected(size)
         }
     }
 }

parsley/shared/src/main/scala/parsley/internal/machine/errors/DefuncHints.scala

@@ -20,7 +20,7 @@ private [machine] sealed abstract class DefuncHints {
     /** This function evaluates this `DefuncHints` structure into the actual set of
       * error items it represents and adds this directly into the provided `TrivialErrorBuilder`
       */
-    private [machine] def updateExpectedsAndGetSize(builder: TrivialErrorBuilder): Int = {
+    private [machine] def updateExpectedsAndGetSize(builder: TrivialErrorBuilder): Option[Int] = {
         val hintCollector = builder.makeHintCollector
         collect(hintCollector)
         hintCollector.unexpectWidth

parsley/shared/src/main/scala/parsley/internal/machine/instructions/IterativeInstrs.scala

@@ -8,11 +8,12 @@ import scala.collection.mutable
 import parsley.internal.machine.Context
 import parsley.internal.machine.XAssert._
 
+// TODO: Now PushHandlerAndCheck(label, false), so could be removed again!
 private [internal] final class PushHandlerIterative(var label: Int) extends InstrWithLabel {
     override def apply(ctx: Context): Unit = {
         ensureRegularInstruction(ctx)
         // This is used for iterative parsers, which must ensure that invalidated hints are invalided _now_
-        ctx.invalidateHints()
+        //ctx.invalidateHints() // FIXME: This has been removed because hint setting in updateCheckOffsetAndHints has been disabled, pending deep thought
         ctx.pushCheck()
         ctx.pushHandler(label)
         ctx.inc()