modelbuilder: propose hints when a class is not found

Signed-off-by: Jean Privat <jean@pryen.org>

diff --git a/src/modelbuilder_base.nit b/src/modelbuilder_base.nit
index 06f2396..5c64d23 100644 (file)
--- a/src/modelbuilder_base.nit
+++ b/src/modelbuilder_base.nit
@@ -301,7 +301,51 @@ class ModelBuilder
                        end
                end
 
-               # If everything fail, then give up :(
+               # If everything fail, then give up with class by proposing things.
+               #
+               # TODO Give hints on formal types (param and virtual)
+               # TODO How to move this in a libified autonomous code?
+
+               var all_classes = model.get_mclasses_by_name(name)
+
+               # Look for imported but invisible classes.
+               if all_classes != null then for c in all_classes do
+                       if not mmodule.in_importation <= c.intro_mmodule then continue
+                       error(ntype, "Error: class `{c.full_name}` not visible in module `{mmodule}`.")
+                       return null
+               end
+
+               # Look for not imported but known classes from importable modules
+               var hints = new Array[String]
+               if all_classes != null then for c in all_classes do
+                       if c.intro_mmodule.in_importation <= mmodule then continue
+                       if c.visibility <= private_visibility then continue
+                       hints.add "`{c.intro_mmodule.full_name}`"
+               end
+               if hints.not_empty then
+                       error(ntype, "Error: class `{name}` not found in module `{mmodule}`. Maybe import {hints.join(",", " or ")}?")
+                       return null
+               end
+
+               # Look for classes with an approximative name.
+               var bestd = name.length / 2 # limit up to 50% name change
+               for c in model.mclasses do
+                       if not mmodule.in_importation <= c.intro_mmodule then continue
+                       if not mmodule.is_visible(c.intro_mmodule, c.visibility) then continue
+                       var d = name.levenshtein_distance(c.name)
+                       if d <= bestd then
+                               if d < bestd then
+                                       hints.clear
+                                       bestd = d
+                               end
+                               hints.add "`{c.name}`"
+                       end
+               end
+               if hints.not_empty then
+                       error(ntype, "Error: class `{name}` not found in module `{mmodule}`. Did you mean {hints.join(",", " or ")}?")
+                       return null
+               end
+
                error(ntype, "Error: class `{name}` not found in module `{mmodule}`.")
                return null
        end