parser: add `ASTDump` and `ANode::dump_tree`

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

diff --git a/src/parser/parser_nodes.nit b/src/parser/parser_nodes.nit
index 289ad53..1c0eb21 100644 (file)
--- a/src/parser/parser_nodes.nit
+++ b/src/parser/parser_nodes.nit
@@ -17,6 +17,7 @@
 module parser_nodes
 
 import location
+import ordered_tree
 
 # Root of the AST class-hierarchy
 abstract class ANode
@@ -33,6 +34,15 @@ abstract class ANode
                sys.stderr.write "{hot_location} {self.class_name}: {message}\n{hot_location.colored_line("0;32")}\n"
        end
 
+       # Write the subtree on stdout.
+       # See `ASTDump`
+       fun dump_tree
+       do
+               var d = new ASTDump
+               d.enter_visit(self)
+               d.write_to(sys.stdout)
+       end
+
        # Parent of the node in the AST
        var parent: nullable ANode = null
 
@@ -158,6 +168,33 @@ private class CollectAnnotationsByNameVisitor
        end
 end
 
+# A helper class to handle (print) Nit AST as an OrderedTree
+class ASTDump
+       super Visitor
+       super OrderedTree[ANode]
+
+       # Reference to the last parent in the Ordered Tree
+       # Is used to handle the initial node parent and workaround possible inconsistent `ANode::parent`
+       private var last_parent: nullable ANode = null
+
+       redef fun visit(n)
+       do
+               var p = last_parent
+               add(p, n)
+               last_parent = n
+               n.visit_all(self)
+               last_parent = p
+       end
+
+       redef fun display(n)
+       do
+               if n isa Token then
+                       return "{n.class_name} \"{n.text.escape_to_c}\" @{n.location}"
+               else
+                       return "{n.class_name} @{n.location}"
+               end
+       end
+end
 
 # A sequence of nodes
 # It is a specific class (instead of using a Array) to track the parent/child relation when nodes are added or removed