diff --git a/ChangeLog b/ChangeLog
index 9068c55126..8cb2ac1e6b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+Wed Dec  9 22:57:04 2009  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* node.c: node management added.  Currently, only pretty-dumper is
+	  implemented.  [ruby-dev:39853]
+	
+	* ruby.c: --dump=parsetree and --dump=parsetree_with_comment options
+	  added.  This is just for debug or research purpose.  Note that the
+	  compatibility of these options are not supported at all.
+
 Wed Dec  9 09:50:35 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* string.c (rb_str_justify): fixed the case a fill size is a
diff --git a/common.mk b/common.mk
index d11866c8c1..45d03c8f7d 100644
--- a/common.mk
+++ b/common.mk
@@ -47,6 +47,7 @@ COMMONOBJS    = array.$(OBJEXT) \
 		io.$(OBJEXT) \
 		marshal.$(OBJEXT) \
 		math.$(OBJEXT) \
+		node.$(OBJEXT) \
 		numeric.$(OBJEXT) \
 		object.$(OBJEXT) \
 		pack.$(OBJEXT) \
@@ -559,6 +560,8 @@ main.$(OBJEXT): {$(VPATH)}main.c $(RUBY_H_INCLUDES) {$(VPATH)}debug.h \
 marshal.$(OBJEXT): {$(VPATH)}marshal.c $(RUBY_H_INCLUDES) {$(VPATH)}io.h \
   $(ENCODING_H_INCLUDES) {$(VPATH)}util.h
 math.$(OBJEXT): {$(VPATH)}math.c $(RUBY_H_INCLUDES)
+node.$(OBJEXT): {$(VPATH)}node.c $(RUBY_H_INCLUDES) \
+  $(VM_CORE_H_INCLUDES)
 numeric.$(OBJEXT): {$(VPATH)}numeric.c $(RUBY_H_INCLUDES) \
   {$(VPATH)}util.h $(ENCODING_H_INCLUDES)
 object.$(OBJEXT): {$(VPATH)}object.c $(RUBY_H_INCLUDES) {$(VPATH)}util.h
diff --git a/node.c b/node.c
new file mode 100644
index 0000000000..c4cac9e2d8
--- /dev/null
+++ b/node.c
@@ -0,0 +1,919 @@
+/**********************************************************************
+
+  node.c - ruby node tree
+
+  $Author: mame $
+  created at: 09/12/06 21:23:44 JST
+
+  Copyright (C) 2009 Yusuke Endoh
+
+**********************************************************************/
+
+#include "ruby/ruby.h"
+#include "vm_core.h"
+
+#define A(str) rb_str_cat2(buf, (str))
+#define AR(str) rb_str_concat(buf, (str))
+
+#define A_INDENT add_indent(buf, indent)
+#define A_ID(id) add_id(buf, id)
+#define A_INT(val) rb_str_catf(buf, "%d", (val));
+#define A_LIT(lit) AR(rb_inspect(lit))
+#define A_NODE_HEADER(node) \
+    rb_str_catf(buf, "@ %s (line: %d)", ruby_node_name(nd_type(node)), nd_line(node))
+#define A_FIELD_HEADER(name) \
+    rb_str_catf(buf, "+- %s:", name)
+
+#define D_NULL_NODE A_INDENT; A("(null node)"); A("\n");
+#define D_NODE_HEADER(node) A_INDENT; A_NODE_HEADER(node); A("\n");
+
+#define COMPOUND_FIELD(name, name2, block) \
+    do { \
+	A_INDENT; A_FIELD_HEADER(comment ? name2 : name); A("\n"); \
+	rb_str_cat2(indent, next_indent); \
+	block; \
+	rb_str_resize(indent, RSTRING_LEN(indent) - 4); \
+    } while (0)
+
+#define SIMPLE_FIELD(name, name2, block) \
+    do { \
+	A_INDENT; A_FIELD_HEADER(comment ? name2 : name); A(" "); block; A("\n"); \
+    } while (0)
+
+#define F_CUSTOM1(name, ann, block) SIMPLE_FIELD(#name, #name " (" ann ")", block)
+#define F_ID(name, ann)		    SIMPLE_FIELD(#name, #name " (" ann ")", A_ID(node->name))
+#define F_GENTRY(name, ann)	    SIMPLE_FIELD(#name, #name " (" ann ")", A_ID((node->name)->id))
+#define F_INT(name, ann)	    SIMPLE_FIELD(#name, #name " (" ann ")", A_INT(node->name))
+#define F_LIT(name, ann)	    SIMPLE_FIELD(#name, #name " (" ann ")", A_LIT(node->name))
+#define F_MSG(name, ann, desc)	    SIMPLE_FIELD(#name, #name " (" ann ")", A(desc))
+
+#define F_CUSTOM2(name, ann, block) \
+    COMPOUND_FIELD(#name, #name " (" ann ")", block)
+
+#define F_NODE(name, ann) \
+    COMPOUND_FIELD(#name, #name " (" ann ")", dump_node(buf, indent, comment, node->name))
+
+#define ANN(ann) \
+    if (comment) { \
+	A_INDENT; A("| # "); A(ann); A("\n"); \
+    }
+
+#define LAST_NODE (next_indent = "    ")
+
+static void
+add_indent(VALUE buf, VALUE indent)
+{
+    AR(indent);
+}
+
+static void
+add_id(VALUE buf, ID id)
+{
+    if (id == 0) {
+	A("(null)");
+    }
+    else {
+	VALUE str = rb_id2str(id);
+	if (str) {
+	    A(":"); AR(rb_id2str(id));
+	}
+	else {
+	    A("(internal variable)");
+	}
+    }
+}
+
+static void
+dump_node(VALUE buf, VALUE indent, int comment, NODE *node)
+{
+    const char *next_indent = "|   ";
+
+    if (!node) {
+	D_NULL_NODE;
+	return;
+    }
+
+    D_NODE_HEADER(node);
+
+    switch (nd_type(node)) {
+      case NODE_BLOCK:
+	ANN("statement sequence");
+	ANN("format: [nd_head]; [nd_next]");
+	ANN("example: foo; bar");
+	F_NODE(nd_head, "current statement");
+	LAST_NODE;
+	F_NODE(nd_next, "next block");
+	break;
+
+      case NODE_IF:
+	ANN("if statement");
+	ANN("format: if [nd_cond] then [nd_body] else [nd_else] end");
+	ANN("example: if x == 1 then foo else bar end");
+	F_NODE(nd_cond, "condition expr");
+	F_NODE(nd_body, "then clause");
+	LAST_NODE;
+	F_NODE(nd_else, "else clause");
+	break;
+
+      case NODE_CASE:
+	ANN("case statement");
+	ANN("format: case [nd_head]; [nd_body]; end");
+	ANN("example: case x; when 1; foo; when 2; bar; else baz; end");
+	F_NODE(nd_head, "case expr");
+	LAST_NODE;
+	F_NODE(nd_body, "when clauses");
+	break;
+
+      case NODE_WHEN:
+	ANN("if statement");
+	ANN("format: when [nd_head]; [nd_body]; (when or else) [nd_next]");
+	ANN("example: case x; when 1; foo; when 2; bar; else baz; end");
+	F_NODE(nd_head, "when value");
+	F_NODE(nd_body, "when clause");
+	LAST_NODE;
+	F_NODE(nd_next, "next when clause");
+	break;
+
+      case NODE_OPT_N:
+	ANN("wrapper for -n option");
+	ANN("format: ruby -ne '[nd_body]' (nd_cond is `gets')");
+	ANN("example: ruby -ne 'p $_'");
+	goto loop;
+      case NODE_WHILE:
+	ANN("while statement");
+	ANN("format: while [nd_cond]; [nd_body]; end");
+	ANN("example: while x == 1; foo; end");
+	goto loop;
+      case NODE_UNTIL:
+	ANN("until statement");
+	ANN("format: until [nd_cond]; [nd_body]; end");
+	ANN("example: until x == 1; foo; end");
+	loop:
+	F_CUSTOM1(nd_state, "begin-end-while?", {
+	   A_INT(node->nd_state);
+	   A((node->nd_state == 1) ? " (while-end)" : " (begin-end-while)");
+	});
+	F_NODE(nd_cond, "condition");
+	LAST_NODE;
+	F_NODE(nd_body, "body");
+	break;
+
+      case NODE_ITER:
+	ANN("method call with block");
+	ANN("format: [nd_iter] { [nd_body] }");
+	ANN("example: 3.times { foo }");
+	goto iter;
+      case NODE_FOR:
+	ANN("for statement");
+	ANN("format: for * in [nd_iter] do [nd_body] end");
+	ANN("example: for i in 1..3 do foo end");
+	iter:
+	F_NODE(nd_iter, "iteration receiver");
+	LAST_NODE;
+	F_NODE(nd_body, "body");
+	break;
+
+      case NODE_BREAK:
+	ANN("for statement");
+	ANN("format: break [nd_stts]");
+	ANN("example: break 1");
+	goto jump;
+      case NODE_NEXT:
+	ANN("next statement");
+	ANN("format: next [nd_stts]");
+	ANN("example: next 1");
+	goto jump;
+      case NODE_RETURN:
+	ANN("return statement");
+	ANN("format: return [nd_stts]");
+	ANN("example: return 1");
+        jump:
+	LAST_NODE;
+	F_NODE(nd_stts, "value");
+	break;
+
+      case NODE_REDO:
+	ANN("redo statement");
+	ANN("format: redo");
+	ANN("example: redo");
+	break;
+
+      case NODE_RETRY:
+	ANN("retry statement");
+	ANN("format: retry");
+	ANN("example: retry");
+	break;
+
+      case NODE_BEGIN:
+	ANN("begin statement");
+	ANN("format: begin; [nd_body]; end");
+	ANN("example: begin; 1; end");
+	LAST_NODE;
+	F_NODE(nd_body, "body");
+	break;
+
+      case NODE_RESCUE:
+	ANN("rescue clause");
+	ANN("format: begin; [nd_body]; (rescue) [nd_resq]; else [nd_else]; end");
+	ANN("example: begin; foo; rescue; bar; else; baz; end");
+	F_NODE(nd_head, "body");
+	F_NODE(nd_resq, "rescue clause list");
+	LAST_NODE;
+	F_NODE(nd_else, "rescue else clause");
+	break;
+
+      case NODE_RESBODY:
+	ANN("rescue clause (cont'd)");
+	ANN("format: rescue [nd_args]; [nd_body]; (rescue) [nd_head]");
+	ANN("example: begin; foo; rescue; bar; else; baz; end");
+	F_NODE(nd_args, "rescue exceptions");
+	F_NODE(nd_body, "rescue clause");
+	LAST_NODE;
+	F_NODE(nd_head, "next rescue clause");
+	break;
+
+      case NODE_ENSURE:
+	ANN("ensure clause");
+	ANN("format: begin; [nd_head]; ensure; [nd_ensr]; end");
+	ANN("example: begin; foo; ensure; bar; end");
+	F_NODE(nd_head, "body");
+	LAST_NODE;
+	F_NODE(nd_ensr, "ensure clause");
+	break;
+
+      case NODE_AND:
+	ANN("&& operator");
+	ANN("format: [nd_1st] && [nd_2nd]");
+	ANN("example: foo && bar");
+	goto andor;
+      case NODE_OR:
+	ANN("|| operator");
+	ANN("format: [nd_1st] || [nd_2nd]");
+	ANN("example: foo && bar");
+	andor:
+	F_NODE(nd_1st, "left expr");
+	LAST_NODE;
+	F_NODE(nd_2nd, "right expr");
+	break;
+
+      case NODE_MASGN:
+	ANN("multiple assignment");
+	ANN("format: [nd_head], [nd_args] = [nd_value]");
+	ANN("example: a, b = foo");
+	F_NODE(nd_value, "rhsn");
+	F_NODE(nd_head, "lhsn");
+	if ((VALUE)node->nd_args != (VALUE)-1) {
+	    LAST_NODE;
+	    F_NODE(nd_args, "splatn");
+	}
+	else {
+	    F_MSG(nd_args, "splatn", "-1 (rest argument without name)");
+	}
+	break;
+
+      case NODE_LASGN:
+	ANN("local variable assignment");
+	ANN("format: [nd_vid](lvar) = [nd_value]");
+	ANN("example: x = foo");
+	goto asgn;
+      case NODE_DASGN:
+	ANN("dynamic variable assignment (out of current scope)");
+	ANN("format: [nd_vid](dvar) = [nd_value]");
+	ANN("example: x = nil; 1.times { x = foo }");
+	goto asgn;
+      case NODE_DASGN_CURR:
+	ANN("dynamic variable assignment (in current scope)");
+	ANN("format: [nd_vid](current dvar) = [nd_value]");
+	ANN("example: 1.times { x = foo }");
+	goto asgn;
+      case NODE_IASGN:
+	ANN("instance variable assignment");
+	ANN("format: [nd_vid](ivar) = [nd_value]");
+	ANN("example: @x = foo");
+	goto asgn;
+      case NODE_CVASGN:
+	ANN("class variable assignment");
+	ANN("format: [nd_vid](cvar) = [nd_value]");
+	ANN("example: @@x = foo");
+	asgn:
+	F_ID(nd_vid, "variable");
+	LAST_NODE;
+	F_NODE(nd_value, "rvalue");
+	break;
+
+      case NODE_GASGN:
+	ANN("global variable assignment");
+	ANN("format: [nd_entry](gvar) = [nd_value]");
+	ANN("example: $x = foo");
+	F_GENTRY(nd_entry, "global variable");
+	LAST_NODE;
+	F_NODE(nd_value, "rvalue");
+	break;
+
+      case NODE_CDECL:
+	ANN("constant declaration");
+	ANN("format: [nd_else]::[nd_vid](constant) = [nd_value]");
+	ANN("example: X = foo");
+	if (node->nd_vid) {
+	   F_ID(nd_vid, "variable");
+	   F_MSG(nd_else, "extension", "not used");
+	}
+	else {
+	   F_MSG(nd_vid, "variable", "0 (see extension field)");
+	   F_NODE(nd_else, "extension");
+	}
+	LAST_NODE;
+	F_NODE(nd_value, "rvalue");
+	break;
+
+      case NODE_OP_ASGN1:
+	ANN("array assignment with operator");
+	ANN("format: [nd_value] [ [nd_args->nd_body] ] [nd_vid]= [nd_args->nd_head]");
+	ANN("example: ary[1] += foo");
+	F_NODE(nd_recv, "receiver");
+	F_ID(nd_vid, "operator");
+	F_NODE(nd_args->nd_body, "index");
+	LAST_NODE;
+	F_NODE(nd_args->nd_head, "rvalue");
+	break;
+
+      case NODE_OP_ASGN2:
+	ANN("attr assignment with operator");
+	ANN("format: [nd_value].[attr] [nd_next->nd_mid]= [nd_value]");
+	ANN("          where [attr] reader: [nd_next->nd_vid]");
+	ANN("                [attr] writer: [nd_next->nd_aid]");
+	ANN("example: struct.field += foo");
+	F_NODE(nd_recv, "receiver");
+	F_ID(nd_next->nd_vid, "reader");
+	F_ID(nd_next->nd_aid, "writer");
+	F_CUSTOM1(nd_next->nd_mid, "operator", {
+	   switch (node->nd_next->nd_mid) {
+	   case 0: A("0 (||)"); break;
+	   case 1: A("1 (&&)"); break;
+	   default: A_ID(node->nd_next->nd_mid);
+	   }
+	});
+	LAST_NODE;
+	F_NODE(nd_value, "rvalue");
+	break;
+
+      case NODE_OP_ASGN_AND:
+	ANN("assignment with && operator");
+	ANN("format: [nd_head] &&= [nd_value]");
+	ANN("example: foo &&= bar");
+	goto asgn_andor;
+      case NODE_OP_ASGN_OR:
+	ANN("assignment with || operator");
+	ANN("format: [nd_head] ||= [nd_value]");
+	ANN("example: foo ||= bar");
+	asgn_andor:
+	F_NODE(nd_head, "variable");
+	LAST_NODE;
+	F_NODE(nd_value, "rvalue");
+	break;
+
+      case NODE_CALL:
+	ANN("method invocation");
+	ANN("format: [nd_recv].[nd_mid]([nd_args])");
+	ANN("example: obj.foo(1)");
+	F_ID(nd_mid, "method id");
+	F_NODE(nd_recv, "receiver");
+	LAST_NODE;
+	F_NODE(nd_args, "arguments");
+	break;
+
+      case NODE_FCALL:
+	ANN("function call");
+	ANN("format: [nd_mid]([nd_args])");
+	ANN("example: foo(1)");
+	F_ID(nd_mid, "method id");
+	LAST_NODE;
+	F_NODE(nd_args, "arguments");
+	break;
+
+      case NODE_VCALL:
+	ANN("function call with no argument");
+	ANN("format: [nd_mid]");
+	ANN("example: foo");
+	F_ID(nd_mid, "method id");
+	break;
+
+      case NODE_SUPER:
+	ANN("super invocation");
+	ANN("format: super [nd_args]");
+	ANN("example: super 1");
+	LAST_NODE;
+	F_NODE(nd_args, "arguments");
+	break;
+
+      case NODE_ZSUPER:
+	ANN("super invocation with no argument");
+	ANN("format: super");
+	ANN("example: super");
+	break;
+
+      case NODE_ARRAY:
+	ANN("array constructor");
+	ANN("format: [ [nd_head], [nd_next].. ] (length: [nd_alen])");
+	ANN("example: [1, 2, 3]");
+	goto ary;
+      case NODE_VALUES:
+	ANN("return arguments");
+	ANN("format: [ [nd_head], [nd_next].. ] (length: [nd_alen])");
+	ANN("example: return 1, 2, 3");
+	ary:
+	F_INT(nd_alen, "length");
+	F_NODE(nd_head, "element");
+	LAST_NODE;
+	F_NODE(nd_next, "next element");
+	break;
+
+      case NODE_ZARRAY:
+	ANN("empty array constructor");
+	ANN("format: []");
+	ANN("example: []");
+	break;
+
+      case NODE_HASH:
+	ANN("hash constructor");
+	ANN("format: { [nd_head] }");
+	ANN("example: { 1 => 2, 3 => 4 }");
+	LAST_NODE;
+	F_NODE(nd_head, "contents");
+	break;
+
+      case NODE_YIELD:
+	ANN("yield invocation");
+	ANN("format: yield [nd_head]");
+	ANN("example: yield 1");
+	LAST_NODE;
+	F_NODE(nd_head, "arguments");
+	break;
+
+      case NODE_LVAR:
+	ANN("local variable reference");
+	ANN("format: [nd_vid](lvar)");
+	ANN("example: x");
+	goto var;
+      case NODE_DVAR:
+	ANN("dynamic variable reference");
+	ANN("format: [nd_vid](dvar)");
+	ANN("example: 1.times { x = 1; x }");
+	goto var;
+      case NODE_IVAR:
+	ANN("instance variable reference");
+	ANN("format: [nd_vid](ivar)");
+	ANN("example: @x");
+	goto var;
+      case NODE_CONST:
+	ANN("constant reference");
+	ANN("format: [nd_vid](constant)");
+	ANN("example: X");
+	goto var;
+      case NODE_CVAR:
+	ANN("class variable reference");
+	ANN("format: [nd_vid](cvar)");
+	ANN("example: @@x");
+        var:
+	F_ID(nd_vid, "local variable");
+	break;
+
+      case NODE_GVAR:
+	ANN("global variable reference");
+	ANN("format: [nd_entry](gvar)");
+	ANN("example: $x");
+	F_GENTRY(nd_entry, "global variable");
+	break;
+
+      case NODE_NTH_REF:
+	ANN("nth special variable reference");
+	ANN("format: $[nd_nth]");
+	ANN("example: $1, $2, ..");
+	F_CUSTOM1(nd_nth, "variable", { A("$"); A_INT(node->nd_nth); });
+	break;
+
+      case NODE_BACK_REF:
+	ANN("back special variable reference");
+	ANN("format: $[nd_nth]");
+	ANN("example: $&, $`, $', $+");
+	F_CUSTOM1(nd_nth, "variable", {
+	   char name[3];
+	   name[0] = '$';
+	   name[1] = node->nd_nth;
+	   name[2] = '\0';
+	   A(name);
+	});
+	break;
+
+      case NODE_MATCH:
+	ANN("match expression (against $_ implicitly)");
+        ANN("format: [nd_lit] (in condition)");
+	ANN("example: if /foo/; foo; end");
+	F_LIT(nd_lit, "regexp");
+	break;
+
+      case NODE_MATCH2:
+	ANN("match expression (regexp first)");
+        ANN("format: [nd_recv] =~ [nd_value]");
+	ANN("example: /foo/ =~ 'foo'");
+	F_NODE(nd_recv, "regexp (receiver)");
+	LAST_NODE;
+	F_NODE(nd_value, "string (argument)");
+	break;
+
+      case NODE_MATCH3:
+	ANN("match expression (regexp second)");
+        ANN("format: [nd_recv] =~ [nd_value]");
+	ANN("example: 'foo' =~ /foo/");
+	F_NODE(nd_recv, "string (receiver)");
+	LAST_NODE;
+	F_NODE(nd_value, "regexp (argument)");
+	break;
+
+      case NODE_LIT:
+	ANN("literal");
+	ANN("format: [nd_lit]");
+	ANN("example: 1, /foo/");
+	goto lit;
+      case NODE_STR:
+	ANN("string literal");
+	ANN("format: [nd_lit]");
+	ANN("example: 'foo'");
+	goto lit;
+      case NODE_XSTR:
+	ANN("xstring literal");
+	ANN("format: [nd_lit]");
+	ANN("example: `foo`");
+	lit:
+	F_LIT(nd_lit, "literal");
+	break;
+
+      case NODE_DSTR:
+	ANN("string literal with interpolation");
+	ANN("format: [nd_lit]");
+	ANN("example: \"foo#{ bar }baz\"");
+	goto dlit;
+      case NODE_DXSTR:
+	ANN("xstring literal with interpolation");
+	ANN("format: [nd_lit]");
+	ANN("example: `foo#{ bar }baz`");
+	goto dlit;
+      case NODE_DREGX:
+	ANN("regexp literal with interpolation");
+	ANN("format: [nd_lit]");
+	ANN("example: /foo#{ bar }baz/");
+	goto dlit;
+      case NODE_DREGX_ONCE:
+	ANN("regexp literal with interpolation and once flag");
+	ANN("format: [nd_lit]");
+	ANN("example: /foo#{ bar }baz/o");
+	goto dlit;
+      case NODE_DSYM:
+	ANN("symbol literal with interpolation");
+	ANN("format: [nd_lit]");
+	ANN("example: :\"foo#{ bar }baz\"");
+	dlit:
+	F_LIT(nd_lit, "literal");
+	F_NODE(nd_next->nd_head, "preceding string");
+	LAST_NODE;
+	F_NODE(nd_next->nd_next, "interpolation");
+	break;
+
+      case NODE_EVSTR:
+	ANN("interpolation expression");
+	ANN("format: \"..#{ [nd_lit] }..\"");
+	ANN("example: \"foo#{ bar }baz\"");
+	LAST_NODE;
+	F_NODE(nd_body, "body");
+	break;
+
+      case NODE_ARGSCAT:
+	ANN("splat argument following arguments");
+	ANN("format: ..(*[nd_head], [nd_body..])");
+	ANN("example: foo(*ary, post_arg1, post_arg2)");
+	F_NODE(nd_head, "preceding array");
+	LAST_NODE;
+	F_NODE(nd_body, "following array");
+	break;
+
+      case NODE_ARGSPUSH:
+	ANN("splat argument following one argument");
+	ANN("format: ..(*[nd_head], [nd_body])");
+	ANN("example: foo(*ary, post_arg)");
+	F_NODE(nd_head, "preceding array");
+	LAST_NODE;
+	F_NODE(nd_body, "following element");
+	break;
+
+      case NODE_SPLAT:
+	ANN("splat argument");
+	ANN("format: *[nd_head]");
+	ANN("example: foo(*ary)");
+	LAST_NODE;
+	F_NODE(nd_head, "splat'ed array");
+	break;
+
+      case NODE_BLOCK_PASS:
+	ANN("arguments with block argument");
+	ANN("format: ..([nd_head], &[nd_body])");
+	ANN("example: foo(x, &blk)");
+	F_NODE(nd_head, "other arguments");
+	LAST_NODE;
+	F_NODE(nd_body, "block argument");
+	break;
+
+      case NODE_DEFN:
+	ANN("method definition");
+	ANN("format: def [nd_mid] [nd_defn]; end");
+	ANN("example; def foo; bar; end");
+	F_ID(nd_mid, "method name");
+	LAST_NODE;
+	F_NODE(nd_defn, "method definition");
+	break;
+
+      case NODE_DEFS:
+	ANN("singleton method definition");
+	ANN("format: def [nd_recv].[nd_mid] [nd_defn]; end");
+	ANN("example; def obj.foo; bar; end");
+	F_NODE(nd_recv, "receiver");
+	F_ID(nd_mid, "method name");
+	LAST_NODE;
+	F_NODE(nd_defn, "method definition");
+	break;
+
+      case NODE_ALIAS:
+	ANN("method alias statement");
+	ANN("format: alias [u1.node] [u2.node]");
+	ANN("example: alias bar foo");
+	F_NODE(u1.node, "new name");
+	LAST_NODE;
+	F_NODE(u2.node, "old name");
+	break;
+
+      case NODE_VALIAS:
+	ANN("global variable alias statement");
+	ANN("format: alias [u1.id](gvar) [u2.id](gvar)");
+	ANN("example: alias $y $x");
+	F_ID(u1.id, "new name");
+	F_ID(u2.id, "old name");
+	break;
+
+      case NODE_UNDEF:
+	ANN("method alias statement");
+	ANN("format: undef [u2.node]");
+	ANN("example: undef foo");
+	LAST_NODE;
+	F_NODE(u2.node, "old name");
+	break;
+
+      case NODE_CLASS:
+	ANN("class definition");
+	ANN("format: class [nd_cpath] < [nd_super]; [nd_body]; end");
+	ANN("example: class C2 < C; ..; end");
+	F_NODE(nd_cpath, "class path");
+	F_NODE(nd_super, "superclass");
+	LAST_NODE;
+	F_NODE(nd_body, "class definition");
+	break;
+
+      case NODE_MODULE:
+	ANN("module definition");
+	ANN("format: module [nd_cpath]; [nd_body]; end");
+	ANN("example: module M; ..; end");
+	F_NODE(nd_cpath, "module path");
+	LAST_NODE;
+	F_NODE(nd_body, "module definition");
+	break;
+
+      case NODE_SCLASS:
+	ANN("singleton class definition");
+	ANN("format: class << [nd_recv]; [nd_body]; end");
+	ANN("example: class << obj; ..; end");
+	F_NODE(nd_recv, "receiver");
+	LAST_NODE;
+	F_NODE(nd_body, "singleton class definition");
+	break;
+
+      case NODE_COLON2:
+	ANN("scoped constant reference");
+	ANN("format: [nd_head]::[nd_mid]");
+	ANN("example: M::C");
+	F_ID(nd_mid, "constant name");
+	LAST_NODE;
+	F_NODE(nd_head, "receiver");
+	break;
+
+      case NODE_COLON3:
+	ANN("top-level constant reference");
+	ANN("format: ::[nd_mid]");
+	ANN("example: ::Object");
+	F_ID(nd_mid, "constant name");
+	break;
+
+      case NODE_DOT2:
+	ANN("range constructor (incl.)");
+	ANN("format: [nd_beg]..[nd_end]");
+	ANN("example: 1..5");
+	goto dot;
+      case NODE_DOT3:
+	ANN("range constructor (excl.)");
+	ANN("format: [nd_beg]...[nd_end]");
+	ANN("example: 1...5");
+	goto dot;
+      case NODE_FLIP2:
+	ANN("flip-flop condition (incl.)");
+	ANN("format: [nd_beg]..[nd_end]");
+	ANN("example: if (x==1)..(x==5); foo; end");
+	goto dot;
+      case NODE_FLIP3:
+	ANN("flip-flop condition (excl.)");
+	ANN("format: [nd_beg]...[nd_end]");
+	ANN("example: if (x==1)...(x==5); foo; end");
+	dot:
+	F_NODE(nd_beg, "begin");
+	LAST_NODE;
+	F_NODE(nd_end, "end");
+	break;
+
+      case NODE_SELF:
+	ANN("self");
+	ANN("format: self");
+	ANN("example: self");
+	break;
+
+      case NODE_NIL:
+	ANN("nil");
+	ANN("format: nil");
+	ANN("example: nil");
+	break;
+
+      case NODE_TRUE:
+	ANN("true");
+	ANN("format: true");
+	ANN("example: true");
+	break;
+
+      case NODE_FALSE:
+	ANN("false");
+	ANN("format: false");
+	ANN("example: false");
+	break;
+
+      case NODE_ERRINFO:
+	ANN("virtual reference to $!");
+	ANN("format: rescue => id");
+	ANN("example: rescue => id");
+	break;
+
+      case NODE_DEFINED:
+	ANN("defined? expression");
+	ANN("format: defined?([nd_head])");
+	ANN("example: defined?(foo)");
+	F_NODE(nd_head, "expr");
+	break;
+
+      case NODE_POSTEXE:
+	ANN("post-execution");
+	ANN("format: END { [nd_body] }");
+	ANN("example: END { foo }");
+	LAST_NODE;
+	F_NODE(nd_body, "END clause");
+	break;
+
+      case NODE_ATTRASGN:
+	ANN("attr assignment");
+	ANN("format: [nd_recv].[nd_mid] = [nd_args]");
+	ANN("example: struct.field = foo");
+	if (node->nd_recv == (NODE *) 1) {
+	    F_MSG(nd_recv, "receiver", "1 (self)");
+	}
+	else {
+	    F_NODE(nd_recv, "receiver");
+	}
+	F_ID(nd_mid, "method name");
+	LAST_NODE;
+	F_NODE(nd_args, "arguments");
+	break;
+
+      case NODE_PRELUDE:
+	ANN("pre-execution");
+	ANN("format: BEGIN { [nd_head] }; [nd_body]");
+	ANN("example: bar; BEGIN { foo }");
+	F_NODE(nd_head, "prelude");
+	LAST_NODE;
+	F_NODE(nd_body, "body");
+	break;
+
+      case NODE_LAMBDA:
+	ANN("lambda expression");
+	ANN("format: -> [nd_body]");
+	ANN("example: -> { foo }");
+	LAST_NODE;
+	F_NODE(nd_body, "lambda clause");
+	break;
+
+      case NODE_OPT_ARG:
+	ANN("optional arguments");
+	ANN("format: def method_name([nd_body=some], [nd_next..])");
+	ANN("example: def foo(a, b=1, c); end");
+	F_NODE(nd_body, "body");
+	LAST_NODE;
+	F_NODE(nd_next, "next");
+	break;
+
+      case NODE_POSTARG:
+	ANN("post arguments");
+	ANN("format: *[nd_1st], [nd_2nd..] = ..");
+	ANN("example: a, *rest, z = foo");
+	if ((VALUE)node->nd_1st != (VALUE)-1) {
+	    F_NODE(nd_1st, "rest argument");
+	}
+	else {
+	    F_MSG(nd_1st, "rest argument", "-1 (rest argument without name)");
+	}
+	LAST_NODE;
+	F_NODE(nd_2nd, "post arguments");
+	break;
+
+      case NODE_ARGS_AUX:
+	ANN("method parameters (cont'd)");
+	F_CUSTOM1(nd_rest, "rest argument", {
+	    if (node->nd_rest == 1) A("nil (with last comma)");
+	    else A_ID(node->nd_rest);
+	});
+	F_CUSTOM1(nd_body, "block argument", { A_ID((ID)node->nd_body); });
+	LAST_NODE;
+	F_CUSTOM2(nd_next, "aux info 2", {
+	    node = node->nd_next;
+	    next_indent = "|    ";
+	    if (!node) {
+		D_NULL_NODE;
+	    }
+	    else {
+		D_NODE_HEADER(node);
+		ANN("method parameters (cont'd)");
+		F_ID(nd_pid, "first post argument");
+		F_INT(nd_plen, "post argument length");
+		LAST_NODE;
+		F_CUSTOM2(nd_next, "aux info 3", {
+		    node = node->nd_next;
+		    next_indent = "|   ";
+		    if (!node) {
+			D_NULL_NODE;
+		    }
+		    else {
+			D_NODE_HEADER(node);
+			ANN("method parameters (cont'd)");
+			F_NODE(nd_1st, "init arguments (m)");
+			LAST_NODE;
+			F_NODE(nd_2nd, "init arguments (p)");
+		    }
+		});
+	    }
+	});
+	break;
+
+      case NODE_ARGS:
+	ANN("method parameters");
+	ANN("format: def method_name(.., [nd_opt=some], *[nd_rest], [nd_pid], .., &[nd_body])");
+	ANN("example: def foo(a, b, opt1=1, opt2=2, *rest, y, z, &blk); end");
+	F_INT(nd_frml, "argc");
+	F_NODE(nd_next, "aux info 1");
+	LAST_NODE;
+	F_NODE(nd_opt, "optional arguments");
+	break;
+
+      case NODE_SCOPE:
+	ANN("new scope");
+	ANN("format: [nd_tbl]: local table, [nd_args]: arguments, [nd_body]: body");
+	F_CUSTOM1(nd_tbl, "local table", {
+	   ID *tbl = node->nd_tbl;
+	   int i;
+	   int size = tbl ? (int)*tbl++ : 0;
+	   if (size == 0) A("(empty)");
+	   for (i = 0; i < size; i++) {
+		A_ID(tbl[i]); if (i < size - 1) A(",");
+	   }
+	});
+	F_NODE(nd_args, "arguments");
+	LAST_NODE;
+	F_NODE(nd_body, "body");
+	break;
+
+      default:
+	rb_bug("dump_node: unknown node: %s", ruby_node_name(nd_type(node)));
+    }
+}
+
+VALUE
+rb_parser_dump_tree(NODE *node, int comment)
+{
+    VALUE buf = rb_str_new_cstr(
+	"###########################################################\n"
+	"## Do NOT use this node dump for any purpose other than  ##\n"
+	"## debug and research.  Compatibility is not guaranteed. ##\n"
+	"###########################################################\n\n"
+    );
+    dump_node(buf, rb_str_new_cstr("# "), comment, node);
+    return buf;
+}
diff --git a/ruby.c b/ruby.c
index a9632e153b..c9cd10d687 100644
--- a/ruby.c
+++ b/ruby.c
@@ -71,6 +71,8 @@ enum dump_flag_bits {
     dump_usage,
     dump_yydebug,
     dump_syntax,
+    dump_parsetree,
+    dump_parsetree_with_comment,
     dump_insns,
     dump_flag_count
 };
@@ -645,9 +647,11 @@ dump_option(const char *str, int len, void *arg)
     SET_WHEN_DUMP(usage);
     SET_WHEN_DUMP(yydebug);
     SET_WHEN_DUMP(syntax);
+    SET_WHEN_DUMP(parsetree);
+    SET_WHEN_DUMP(parsetree_with_comment);
     SET_WHEN_DUMP(insns);
     rb_warn("don't know how to dump `%.*s',", len, str);
-    rb_warn("but only [version, copyright, usage, yydebug, syntax, insns].");
+    rb_warn("but only [version, copyright, usage, yydebug, syntax, parsetree, parsetree_with_comment, insns].");
 }
 
 static void
@@ -1433,6 +1437,12 @@ process_options(int argc, char **argv, struct cmdline_options *opt)
 	rb_define_global_function("chomp", rb_f_chomp, -1);
     }
 
+    if (opt->dump & DUMP_BIT(parsetree) || opt->dump & DUMP_BIT(parsetree_with_comment)) {
+	rb_io_write(rb_stdout, rb_parser_dump_tree(tree, opt->dump & DUMP_BIT(parsetree_with_comment)));
+	rb_io_flush(rb_stdout);
+	return Qtrue;
+    }
+
     PREPARE_PARSE_MAIN({
 	iseq = rb_iseq_new_main(tree, opt->script_name);
     });