X-Git-Url: http://nitlanguage.org

diff --git a/lib/nitcc_runtime.nit b/lib/nitcc_runtime.nit
index 31c0a45..bfd137d 100644
--- a/lib/nitcc_runtime.nit
+++ b/lib/nitcc_runtime.nit
@@ -274,7 +274,7 @@ end
 # Print a node (using to_s) on a line and recustively each children indented (with two spaces)
 class TreePrinterVisitor
 	super Visitor
-	var writer: OStream
+	var writer: Writer
 	private var indent = 0
 	redef fun visit(n)
 	do
@@ -296,7 +296,42 @@ class Position
 	var line_end: Int
 	var col_start: Int
 	var col_end: Int
+
 	redef fun to_s do return "{line_start}:{col_start}-{line_end}:{col_end}"
+
+	# Get the lines covered by `self` and underline the target columns.
+	#
+	# This is useful for pretty printing errors or debug the output
+	#
+	# ~~~
+	# var src = "var Foo = new Array[Int]"
+	# var pos = new Position(0,0, 1, 1, 5, 8)
+	#
+	# assert pos.underline(src) == """
+	# var Foo = new Array[Int]
+	#     ^^^"""
+	# ~~~
+	fun underline(source: Text): String
+	do
+		var res = new FlatBuffer
+
+		# All the concerned lines
+		var lines = source.split("\n")
+		for line in [line_start..line_end] do
+			res.append lines[line-1]
+			res.append "\n"
+		end
+
+		# Cover all columns, no matter their lines
+		var col_start = col_start.min(col_end)
+		var col_end = self.col_start.max(col_end)
+
+		# "           ^^^^"
+		var ptr = " "*(col_start-1).max(0) + "^"*(col_end-col_start)
+		res.append ptr
+
+		return res.to_s
+	end
 end
 
 # A node of a syntactic tree
@@ -322,7 +357,7 @@ abstract class Node
 	# Produce a graphiz file for the syntaxtic tree rooted at `self`.
 	fun to_dot(filepath: String)
 	do
-		var f = new OFStream.open(filepath)
+		var f = new FileWriter.open(filepath)
 		f.write("digraph g \{\n")
 		f.write("rankdir=BT;\n")
 
@@ -346,7 +381,7 @@ abstract class Node
 		f.close
 	end
 
-	private fun to_dot_visitor(f: OStream, a: Array[NToken])
+	private fun to_dot_visitor(f: Writer, a: Array[NToken])
 	do
 		f.write("n{object_id} [label=\"{node_name}\"];\n")
 		for x in children do
@@ -494,7 +529,7 @@ class Nodes[T: Node]
 end
 
 # A production with a specific, named and statically typed children
-class NProd
+abstract class NProd
 	super Node
 	redef var children: SequenceRead[nullable Node] = new NProdChildren(self)
 
@@ -558,7 +593,7 @@ abstract class TestParser
 			end
 			text = args.shift
 		else
-			var f = new IFStream.open(filepath)
+			var f = new FileReader.open(filepath)
 			text = f.read_all
 			f.close
 		end
@@ -582,7 +617,7 @@ abstract class TestParser
 		var tokout = "{name}.tokens.out"
 		print "TOKEN: {tokens.length} tokens (see {tokout})"
 
-		var f = new OFStream.open(tokout)
+		var f = new FileWriter.open(tokout)
 		for t in tokens do
 			f.write "{t.to_s}\n"
 		end
@@ -594,7 +629,7 @@ abstract class TestParser
 		var n = p.parse
 
 		var astout = "{name}.ast.out"
-		f = new OFStream.open(astout)
+		f = new FileWriter.open(astout)
 		var tpv = new TreePrinterVisitor(f)
 		var astdotout = "{name}.ast.dot"
 		if n isa NError then