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package dotty.tools
package dotc
package reporting
package diagnostic
import dotc.core._
import Contexts.Context, Decorators._, Symbols._
import dotc.printing.SyntaxHighlighting._
import util.{SourcePosition, NoSourcePosition}
object syntax {
import dotc.ast.Trees._
import dotc.ast.untpd
abstract class EmptyCatchOrFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context) extends MessageCreator {
val explanation = {
val tryString = tryBody match {
case Block(Nil, untpd.EmptyTree) => "{}"
case _ => tryBody.show
}
val code1 =
s"""|try $tryString catch {
| case t: Throwable => ???
|}""".stripMargin
val code2 =
s"""|try $tryString finally {
| // perform your cleanup here!
|}""".stripMargin
hl"""|Explanation:
|============
|A ${"try"} expression should be followed by some mechanism to handle any exceptions
|thrown. Typically a ${"catch"} expression follows the ${"try"} and pattern matches
|on any expected exceptions. For example:
|
|$code1
|
|It is also possible to follow a ${"try"} immediately by a ${"finally"} - letting the
|exception propagate - but still allowing for some clean up in ${"finally"}:
|
|$code2
""".stripMargin
}
}
class EmptyCatchBlock(tryBody: untpd.Tree)(implicit ctx: Context)
extends EmptyCatchOrFinallyBlock(tryBody) {
val kind = "Syntax"
val msg =
hl"""|The ${"catch"} block does not contain a valid expression, try
|adding a case like - `${"case e: Exception =>"}` to the block""".stripMargin
}
case class EmptyCatchAndFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context)
extends EmptyCatchOrFinallyBlock(tryBody) {
val kind = "Syntax"
val msg =
hl"""|A ${"try"} without ${"catch"} or ${"finally"} is equivalent to putting
|its body in a block; no exceptions are handled.""".stripMargin
}
}
|
