node.c

/**********************************************************************

  node.c - ruby node tree

  $Author: mame $
  created at: 09/12/06 21:23:44 JST

  Copyright (C) 2009 Yusuke Endoh

**********************************************************************/

#include "internal.h"
#include "internal/hash.h"
#include "internal/variable.h"
#include "ruby/ruby.h"
#include "vm_core.h"

#define NODE_BUF_DEFAULT_LEN 16

#define A(str) rb_str_cat2(buf, (str))
#define AR(str) rb_str_concat(buf, (str))

#define A_INDENT add_indent(buf, indent)
#define D_INDENT rb_str_cat2(indent, next_indent)
#define D_DEDENT rb_str_resize(indent, RSTRING_LEN(indent) - 4)
#define A_ID(id) add_id(buf, (id))
#define A_INT(val) rb_str_catf(buf, "%d", (val))
#define A_LONG(val) rb_str_catf(buf, "%ld", (val))
#define A_LIT(lit) AR(rb_dump_literal(lit))
#define A_NODE_HEADER(node, term) \
    rb_str_catf(buf, "@ %s (id: %d, line: %d, location: (%d,%d)-(%d,%d))%s"term, \
                ruby_node_name(nd_type(node)), nd_node_id(node), nd_line(node), \
                nd_first_lineno(node), nd_first_column(node), \
                nd_last_lineno(node), nd_last_column(node), \
                (node->flags & NODE_FL_NEWLINE ? "*" : ""))
#define A_FIELD_HEADER(len, name, term) \
    rb_str_catf(buf, "+- %.*s:"term, (len), (name))
#define D_FIELD_HEADER(len, name, term) (A_INDENT, A_FIELD_HEADER(len, name, term))

#define D_NULL_NODE (A_INDENT, A("(null node)\n"))
#define D_NODE_HEADER(node) (A_INDENT, A_NODE_HEADER(node, "\n"))

#define COMPOUND_FIELD(len, name) \
    FIELD_BLOCK((D_FIELD_HEADER((len), (name), "\n"), D_INDENT), D_DEDENT)

#define COMPOUND_FIELD1(name, ann) \
    COMPOUND_FIELD(FIELD_NAME_LEN(name, ann), \
                   FIELD_NAME_DESC(name, ann))

#define FIELD_NAME_DESC(name, ann) name " (" ann ")"
#define FIELD_NAME_LEN(name, ann) (int)( \
        comment ? \
        rb_strlen_lit(FIELD_NAME_DESC(name, ann)) : \
        rb_strlen_lit(name))
#define SIMPLE_FIELD(len, name) \
    FIELD_BLOCK(D_FIELD_HEADER((len), (name), " "), A("\n"))

#define FIELD_BLOCK(init, reset) \
    for (init, field_flag = 1; \
         field_flag; /* should be optimized away */ \
         reset, field_flag = 0)

#define SIMPLE_FIELD1(name, ann)    SIMPLE_FIELD(FIELD_NAME_LEN(name, ann), FIELD_NAME_DESC(name, ann))
#define F_CUSTOM1(name, ann)	    SIMPLE_FIELD1(#name, ann)
#define F_ID(name, ann) 	    SIMPLE_FIELD1(#name, ann) A_ID(node->name)
#define F_GENTRY(name, ann)	    SIMPLE_FIELD1(#name, ann) A_ID(node->name)
#define F_INT(name, ann)	    SIMPLE_FIELD1(#name, ann) A_INT(node->name)
#define F_LONG(name, ann)	    SIMPLE_FIELD1(#name, ann) A_LONG(node->name)
#define F_LIT(name, ann)	    SIMPLE_FIELD1(#name, ann) A_LIT(node->name)
#define F_MSG(name, ann, desc)	    SIMPLE_FIELD1(#name, ann) A(desc)

#define F_NODE(name, ann) \
    COMPOUND_FIELD1(#name, ann) {dump_node(buf, indent, comment, node->name);}

#define ANN(ann) \
    if (comment) { \
        A_INDENT; A("| # " ann "\n"); \
    }

#define LAST_NODE (next_indent = "    ")

VALUE
rb_dump_literal(VALUE lit)
{
    if (!RB_SPECIAL_CONST_P(lit)) {
        VALUE str;
        switch (RB_BUILTIN_TYPE(lit)) {
          case T_CLASS: case T_MODULE: case T_ICLASS:
            str = rb_class_path(lit);
            if (FL_TEST(lit, FL_SINGLETON)) {
                str = rb_sprintf("<%"PRIsVALUE">", str);
            }
            return str;
          default:
            break;
        }
    }
    return rb_inspect(lit);
}

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(str);
        }
        else {
            rb_str_catf(buf, "(internal variable: 0x%"PRIsVALUE")", id);
        }
    }
}

struct add_option_arg {
    VALUE buf, indent;
    st_index_t count;
};

static void dump_node(VALUE, VALUE, int, const NODE *);
static const char default_indent[] = "|   ";

static void
dump_array(VALUE buf, VALUE indent, int comment, const NODE *node)
{
    int field_flag;
    const char *next_indent = default_indent;
    F_LONG(nd_alen, "length");
    F_NODE(nd_head, "element");
    while (node->nd_next && nd_type_p(node->nd_next, NODE_LIST)) {
        node = node->nd_next;
        F_NODE(nd_head, "element");
    }
    LAST_NODE;
    F_NODE(nd_next, "next element");
}

static void
dump_node(VALUE buf, VALUE indent, int comment, const NODE * node)
{
    int field_flag;
    int i;
    const char *next_indent = default_indent;
    enum node_type type;

    if (!node) {
        D_NULL_NODE;
        return;
    }

    D_NODE_HEADER(node);

    type = nd_type(node);
    switch (type) {
      case NODE_BLOCK:
        ANN("statement sequence");
        ANN("format: [nd_head]; ...; [nd_next]");
        ANN("example: foo; bar");
        i = 0;
        do {
            A_INDENT;
            rb_str_catf(buf, "+- nd_head (%s%d):\n",
                        comment ? "statement #" : "", ++i);
            if (!node->nd_next) LAST_NODE;
            D_INDENT;
            dump_node(buf, indent, comment, node->nd_head);
            D_DEDENT;
        } while (node->nd_next &&
                 nd_type_p(node->nd_next, NODE_BLOCK) &&
                 (node = node->nd_next, 1));
        if (node->nd_next) {
            LAST_NODE;
            F_NODE(nd_next, "next block");
        }
        return;

      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");
        return;

      case NODE_UNLESS:
        ANN("unless statement");
        ANN("format: unless [nd_cond] then [nd_body] else [nd_else] end");
        ANN("example: unless 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");
        return;

      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");
        return;
      case NODE_CASE2:
        ANN("case statement with no head");
        ANN("format: case; [nd_body]; end");
        ANN("example: case; when 1; foo; when 2; bar; else baz; end");
        F_NODE(nd_head, "case expr");
        LAST_NODE;
        F_NODE(nd_body, "when clauses");
        return;
      case NODE_CASE3:
        ANN("case statement (pattern matching)");
        ANN("format: case [nd_head]; [nd_body]; end");
        ANN("example: case x; in 1; foo; in 2; bar; else baz; end");
        F_NODE(nd_head, "case expr");
        LAST_NODE;
        F_NODE(nd_body, "in clauses");
        return;

      case NODE_WHEN:
        ANN("when clause");
        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 body");
        LAST_NODE;
        F_NODE(nd_next, "next when clause");
        return;

      case NODE_IN:
        ANN("in clause");
        ANN("format: in [nd_head]; [nd_body]; (in or else) [nd_next]");
        ANN("example: case x; in 1; foo; in 2; bar; else baz; end");
        F_NODE(nd_head, "in pattern");
        F_NODE(nd_body, "in body");
        LAST_NODE;
        F_NODE(nd_next, "next in clause");
        return;

      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((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");
        return;

      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");
        return;

      case NODE_FOR_MASGN:
        ANN("vars of for statement with masgn");
        ANN("format: for [nd_var] in ... do ... end");
        ANN("example: for x, y in 1..3 do foo end");
        LAST_NODE;
        F_NODE(nd_var, "var");
        return;

      case NODE_BREAK:
        ANN("break 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");
        return;

      case NODE_REDO:
        ANN("redo statement");
        ANN("format: redo");
        ANN("example: redo");
        return;

      case NODE_RETRY:
        ANN("retry statement");
        ANN("format: retry");
        ANN("example: retry");
        return;

      case NODE_BEGIN:
        ANN("begin statement");
        ANN("format: begin; [nd_body]; end");
        ANN("example: begin; 1; end");
        LAST_NODE;
        F_NODE(nd_body, "body");
        return;

      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");
        return;

      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");
        return;

      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");
        return;

      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:
        while (1) {
            F_NODE(nd_1st, "left expr");
            if (!node->nd_2nd || !nd_type_p(node->nd_2nd, type))
                break;
            node = node->nd_2nd;
        }
        LAST_NODE;
        F_NODE(nd_2nd, "right expr");
        return;

      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 (NODE_NAMED_REST_P(node->nd_args)) {
            LAST_NODE;
            F_NODE(nd_args, "splatn");
        }
        else {
            F_MSG(nd_args, "splatn", "NODE_SPECIAL_NO_NAME_REST (rest argument without name)");
        }
        return;

      case NODE_LASGN:
        ANN("local variable assignment");
        ANN("format: [nd_vid](lvar) = [nd_value]");
        ANN("example: x = foo");
        F_ID(nd_vid, "local variable");
        if (NODE_REQUIRED_KEYWORD_P(node)) {
            F_MSG(nd_value, "rvalue", "NODE_SPECIAL_REQUIRED_KEYWORD (required keyword argument)");
        }
        else {
            LAST_NODE;
            F_NODE(nd_value, "rvalue");
        }
        return;
      case NODE_DASGN:
        ANN("dynamic variable assignment");
        ANN("format: [nd_vid](dvar) = [nd_value]");
        ANN("example: x = nil; 1.times { x = foo }");
        ANN("example: 1.times { x = foo }");
        F_ID(nd_vid, "local variable");
        if (NODE_REQUIRED_KEYWORD_P(node)) {
            F_MSG(nd_value, "rvalue", "NODE_SPECIAL_REQUIRED_KEYWORD (required keyword argument)");
        }
        else {
            LAST_NODE;
            F_NODE(nd_value, "rvalue");
        }
        return;
      case NODE_IASGN:
        ANN("instance variable assignment");
        ANN("format: [nd_vid](ivar) = [nd_value]");
        ANN("example: @x = foo");
        F_ID(nd_vid, "instance variable");
        LAST_NODE;
        F_NODE(nd_value, "rvalue");
        return;
      case NODE_CVASGN:
        ANN("class variable assignment");
        ANN("format: [nd_vid](cvar) = [nd_value]");
        ANN("example: @@x = foo");
        F_ID(nd_vid, "class variable");
        LAST_NODE;
        F_NODE(nd_value, "rvalue");
        return;
      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");
        return;

      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, "constant");
            F_MSG(nd_else, "extension", "not used");
        }
        else {
            F_MSG(nd_vid, "constant", "0 (see extension field)");
            F_NODE(nd_else, "extension");
        }
        LAST_NODE;
        F_NODE(nd_value, "rvalue");
        return;

      case NODE_OP_ASGN1:
        ANN("array assignment with operator");
        ANN("format: [nd_recv] [ [nd_args->nd_head] ] [nd_mid]= [nd_args->nd_body]");
        ANN("example: ary[1] += foo");
        F_NODE(nd_recv, "receiver");
        F_ID(nd_mid, "operator");
        F_NODE(nd_args->nd_head, "index");
        LAST_NODE;
        F_NODE(nd_args->nd_body, "rvalue");
        return;

      case NODE_OP_ASGN2:
        ANN("attr assignment with operator");
        ANN("format: [nd_recv].[attr] [nd_next->nd_mid]= [nd_value]");
        ANN("          where [attr]: [nd_next->nd_vid]");
        ANN("example: struct.field += foo");
        F_NODE(nd_recv, "receiver");
        F_CUSTOM1(nd_next->nd_vid, "attr") {
            if (node->nd_next->nd_aid) A("? ");
            A_ID(node->nd_next->nd_vid);
        }
        F_ID(nd_next->nd_mid, "operator");
        LAST_NODE;
        F_NODE(nd_value, "rvalue");
        return;

      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");
        return;

      case NODE_OP_CDECL:
        ANN("constant declaration with operator");
        ANN("format: [nd_head](constant) [nd_aid]= [nd_value]");
        ANN("example: A::B ||= 1");
        F_NODE(nd_head, "constant");
        F_ID(nd_aid, "operator");
        LAST_NODE;
        F_NODE(nd_value, "rvalue");
        return;

      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");
        return;

      case NODE_OPCALL:
        ANN("method invocation");
        ANN("format: [nd_recv] [nd_mid] [nd_args]");
        ANN("example: foo + bar");
        F_ID(nd_mid, "method id");
        F_NODE(nd_recv, "receiver");
        LAST_NODE;
        F_NODE(nd_args, "arguments");
        return;

      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");
        return;

      case NODE_VCALL:
        ANN("function call with no argument");
        ANN("format: [nd_mid]");
        ANN("example: foo");
        F_ID(nd_mid, "method id");
        return;

      case NODE_QCALL:
        ANN("safe 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");
        return;

      case NODE_SUPER:
        ANN("super invocation");
        ANN("format: super [nd_args]");
        ANN("example: super 1");
        LAST_NODE;
        F_NODE(nd_args, "arguments");
        return;

      case NODE_ZSUPER:
        ANN("super invocation with no argument");
        ANN("format: super");
        ANN("example: super");
        return;

      case NODE_LIST:
        ANN("list 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:
        dump_array(buf, indent, comment, node);
        return;

      case NODE_ZLIST:
        ANN("empty list constructor");
        ANN("format: []");
        ANN("example: []");
        return;

      case NODE_HASH:
        if (!node->nd_brace) {
            ANN("keyword arguments");
            ANN("format: nd_head");
            ANN("example: a: 1, b: 2");
        }
        else {
            ANN("hash constructor");
            ANN("format: { [nd_head] }");
            ANN("example: { 1 => 2, 3 => 4 }");
        }
        F_CUSTOM1(nd_brace, "keyword arguments or hash literal") {
            switch (node->nd_brace) {
              case 0: A("0 (keyword argument)"); break;
              case 1: A("1 (hash literal)"); break;
            }
        }
        LAST_NODE;
        F_NODE(nd_head, "contents");
        return;

      case NODE_YIELD:
        ANN("yield invocation");
        ANN("format: yield [nd_head]");
        ANN("example: yield 1");
        LAST_NODE;
        F_NODE(nd_head, "arguments");
        return;

      case NODE_LVAR:
        ANN("local variable reference");
        ANN("format: [nd_vid](lvar)");
        ANN("example: x");
        F_ID(nd_vid, "local variable");
        return;
      case NODE_DVAR:
        ANN("dynamic variable reference");
        ANN("format: [nd_vid](dvar)");
        ANN("example: 1.times { x = 1; x }");
        F_ID(nd_vid, "local variable");
        return;
      case NODE_IVAR:
        ANN("instance variable reference");
        ANN("format: [nd_vid](ivar)");
        ANN("example: @x");
        F_ID(nd_vid, "instance variable");
        return;
      case NODE_CONST:
        ANN("constant reference");
        ANN("format: [nd_vid](constant)");
        ANN("example: X");
        F_ID(nd_vid, "constant");
        return;
      case NODE_CVAR:
        ANN("class variable reference");
        ANN("format: [nd_vid](cvar)");
        ANN("example: @@x");
        F_ID(nd_vid, "class variable");
        return;

      case NODE_GVAR:
        ANN("global variable reference");
        ANN("format: [nd_entry](gvar)");
        ANN("example: $x");
        F_GENTRY(nd_entry, "global variable");
        return;

      case NODE_NTH_REF:
        ANN("nth special variable reference");
        ANN("format: $[nd_nth]");
        ANN("example: $1, $2, ..");
        F_CUSTOM1(nd_nth, "variable") { A("$"); A_LONG(node->nd_nth); }
        return;

      case NODE_BACK_REF:
        ANN("back special variable reference");
        ANN("format: $[nd_nth]");
        ANN("example: $&, $`, $', $+");
        F_CUSTOM1(nd_nth, "variable") {
            char name[3] = "$ ";
            name[1] = (char)node->nd_nth;
            A(name);
        }
        return;

      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");
        return;

      case NODE_MATCH2:
        ANN("match expression (regexp first)");
        ANN("format: [nd_recv] =~ [nd_value]");
        ANN("example: /foo/ =~ 'foo'");
        F_NODE(nd_recv, "regexp (receiver)");
        if (!node->nd_args) LAST_NODE;
        F_NODE(nd_value, "string (argument)");
        if (node->nd_args) {
            LAST_NODE;
            F_NODE(nd_args, "named captures");
        }
        return;

      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)");
        return;

      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");
        return;

      case NODE_ONCE:
        ANN("once evaluation");
        ANN("format: [nd_body]");
        ANN("example: /foo#{ bar }baz/o");
        LAST_NODE;
        F_NODE(nd_body, "body");
        return;
      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_DSYM:
        ANN("symbol literal with interpolation");
        ANN("format: [nd_lit]");
        ANN("example: :\"foo#{ bar }baz\"");
      dlit:
        F_LIT(nd_lit, "preceding string");
        if (!node->nd_next) return;
        F_NODE(nd_next->nd_head, "interpolation");
        LAST_NODE;
        F_NODE(nd_next->nd_next, "tailing strings");
        return;

      case NODE_EVSTR:
        ANN("interpolation expression");
        ANN("format: \"..#{ [nd_lit] }..\"");
        ANN("example: \"foo#{ bar }baz\"");
        LAST_NODE;
        F_NODE(nd_body, "body");
        return;

      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");
        return;

      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");
        return;

      case NODE_SPLAT:
        ANN("splat argument");
        ANN("format: *[nd_head]");
        ANN("example: foo(*ary)");
        LAST_NODE;
        F_NODE(nd_head, "splat'ed array");
        return;

      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");
        return;

      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");
        return;

      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");
        return;

      case NODE_ALIAS:
        ANN("method alias statement");
        ANN("format: alias [nd_1st] [nd_2nd]");
        ANN("example: alias bar foo");
        F_NODE(nd_1st, "new name");
        LAST_NODE;
        F_NODE(nd_2nd, "old name");
        return;

      case NODE_VALIAS:
        ANN("global variable alias statement");
        ANN("format: alias [nd_alias](gvar) [nd_orig](gvar)");
        ANN("example: alias $y $x");
        F_ID(nd_alias, "new name");
        F_ID(nd_orig, "old name");
        return;

      case NODE_UNDEF:
        ANN("method undef statement");
        ANN("format: undef [nd_undef]");
        ANN("example: undef foo");
        LAST_NODE;
        F_NODE(nd_undef, "old name");
        return;

      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");
        return;

      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");
        return;

      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");
        return;

      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");
        return;

      case NODE_COLON3:
        ANN("top-level constant reference");
        ANN("format: ::[nd_mid]");
        ANN("example: ::Object");
        F_ID(nd_mid, "constant name");
        return;

      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");
        return;

      case NODE_SELF:
        ANN("self");
        ANN("format: self");
        ANN("example: self");
        return;

      case NODE_NIL:
        ANN("nil");
        ANN("format: nil");
        ANN("example: nil");
        return;

      case NODE_TRUE:
        ANN("true");
        ANN("format: true");
        ANN("example: true");
        return;

      case NODE_FALSE:
        ANN("false");
        ANN("format: false");
        ANN("example: false");
        return;

      case NODE_ERRINFO:
        ANN("virtual reference to $!");
        ANN("format: rescue => id");
        ANN("example: rescue => id");
        return;

      case NODE_DEFINED:
        ANN("defined? expression");
        ANN("format: defined?([nd_head])");
        ANN("example: defined?(foo)");
        F_NODE(nd_head, "expr");
        return;

      case NODE_POSTEXE:
        ANN("post-execution");
        ANN("format: END { [nd_body] }");
        ANN("example: END { foo }");
        LAST_NODE;
        F_NODE(nd_body, "END clause");
        return;

      case NODE_ATTRASGN:
        ANN("attr assignment");
        ANN("format: [nd_recv].[nd_mid] = [nd_args]");
        ANN("example: struct.field = foo");
        F_NODE(nd_recv, "receiver");
        F_ID(nd_mid, "method name");
        LAST_NODE;
        F_NODE(nd_args, "arguments");
        return;

      case NODE_LAMBDA:
        ANN("lambda expression");
        ANN("format: -> [nd_body]");
        ANN("example: -> { foo }");
        LAST_NODE;
        F_NODE(nd_body, "lambda clause");
        return;

      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");
        return;

      case NODE_KW_ARG:
        ANN("keyword arguments");
        ANN("format: def method_name([nd_body=some], [nd_next..])");
        ANN("example: def foo(a:1, b:2); end");
        F_NODE(nd_body, "body");
        LAST_NODE;
        F_NODE(nd_next, "next");
        return;

      case NODE_POSTARG:
        ANN("post arguments");
        ANN("format: *[nd_1st], [nd_2nd..] = ..");
        ANN("example: a, *rest, z = foo");
        if (NODE_NAMED_REST_P(node->nd_1st)) {
            F_NODE(nd_1st, "rest argument");
        }
        else {
            F_MSG(nd_1st, "rest argument", "NODE_SPECIAL_NO_NAME_REST (rest argument without name)");
        }
        LAST_NODE;
        F_NODE(nd_2nd, "post arguments");
        return;

      case NODE_ARGS:
        ANN("method parameters");
        ANN("format: def method_name(.., [nd_ainfo->nd_optargs], *[nd_ainfo->rest_arg], [nd_ainfo->first_post_arg], .., [nd_ainfo->kw_args], **[nd_ainfo->kw_rest_arg], &[nd_ainfo->block_arg])");
        ANN("example: def foo(a, b, opt1=1, opt2=2, *rest, y, z, kw: 1, **kwrest, &blk); end");
        F_INT(nd_ainfo->pre_args_num, "count of mandatory (pre-)arguments");
        F_NODE(nd_ainfo->pre_init, "initialization of (pre-)arguments");
        F_INT(nd_ainfo->post_args_num, "count of mandatory post-arguments");
        F_NODE(nd_ainfo->post_init, "initialization of post-arguments");
        F_ID(nd_ainfo->first_post_arg, "first post argument");
        F_CUSTOM1(nd_ainfo->rest_arg, "rest argument") {
            if (node->nd_ainfo->rest_arg == NODE_SPECIAL_EXCESSIVE_COMMA) {
                A("1 (excessed comma)");
            }
            else {
                A_ID(node->nd_ainfo->rest_arg);
            }
        }
        F_ID(nd_ainfo->block_arg, "block argument");
        F_NODE(nd_ainfo->opt_args, "optional arguments");
        F_NODE(nd_ainfo->kw_args, "keyword arguments");
        LAST_NODE;
        F_NODE(nd_ainfo->kw_rest_arg, "keyword rest argument");
        return;

      case NODE_SCOPE:
        ANN("new scope");
        ANN("format: [nd_tbl]: local table, [nd_args]: arguments, [nd_body]: body");
        F_CUSTOM1(nd_tbl, "local table") {
            rb_ast_id_table_t *tbl = node->nd_tbl;
            int i;
            int size = tbl ? tbl->size : 0;
            if (size == 0) A("(empty)");
            for (i = 0; i < size; i++) {
                A_ID(tbl->ids[i]); if (i < size - 1) A(",");
            }
        }
        F_NODE(nd_args, "arguments");
        LAST_NODE;
        F_NODE(nd_body, "body");
        return;

      case NODE_ARYPTN:
        ANN("array pattern");
        ANN("format: [nd_pconst]([pre_args], ..., *[rest_arg], [post_args], ...)");
        F_NODE(nd_pconst, "constant");
        F_NODE(nd_apinfo->pre_args, "pre arguments");
        if (NODE_NAMED_REST_P(node->nd_apinfo->rest_arg)) {
            F_NODE(nd_apinfo->rest_arg, "rest argument");
        }
        else {
            F_MSG(nd_apinfo->rest_arg, "rest argument", "NODE_SPECIAL_NO_NAME_REST (rest argument without name)");
        }
        LAST_NODE;
        F_NODE(nd_apinfo->post_args, "post arguments");
        return;

      case NODE_FNDPTN:
        ANN("find pattern");
        ANN("format: [nd_pconst](*[pre_rest_arg], args, ..., *[post_rest_arg])");
        F_NODE(nd_pconst, "constant");
        if (NODE_NAMED_REST_P(node->nd_fpinfo->pre_rest_arg)) {
            F_NODE(nd_fpinfo->pre_rest_arg, "pre rest argument");
        }
        else {
            F_MSG(nd_fpinfo->pre_rest_arg, "pre rest argument", "NODE_SPECIAL_NO_NAME_REST (rest argument without name)");
        }
        F_NODE(nd_fpinfo->args, "arguments");

        LAST_NODE;
        if (NODE_NAMED_REST_P(node->nd_fpinfo->post_rest_arg)) {
            F_NODE(nd_fpinfo->post_rest_arg, "post rest argument");
        }
        else {
            F_MSG(nd_fpinfo->post_rest_arg, "post rest argument", "NODE_SPECIAL_NO_NAME_REST (rest argument without name)");
        }
        return;

      case NODE_HSHPTN:
        ANN("hash pattern");
        ANN("format: [nd_pconst]([nd_pkwargs], ..., **[nd_pkwrestarg])");
        F_NODE(nd_pconst, "constant");
        F_NODE(nd_pkwargs, "keyword arguments");
        LAST_NODE;
        if (node->nd_pkwrestarg == NODE_SPECIAL_NO_REST_KEYWORD) {
            F_MSG(nd_pkwrestarg, "keyword rest argument", "NODE_SPECIAL_NO_REST_KEYWORD (**nil)");
        }
        else {
            F_NODE(nd_pkwrestarg, "keyword rest argument");
        }
        return;
      case NODE_ERROR:
        ANN("Broken input recovered by Error Tolerant mode");
        return;

      case NODE_ARGS_AUX:
      case NODE_LAST:
        break;
    }

    rb_bug("dump_node: unknown node: %s", ruby_node_name(nd_type(node)));
}

VALUE
rb_parser_dump_tree(const 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;
}

/* Setup NODE structure.
 * NODE is not an object managed by GC, but it imitates an object
 * so that it can work with `RB_TYPE_P(obj, T_NODE)`.
 * This dirty hack is needed because Ripper jumbles NODEs and other type
 * objects.
 */
void
rb_node_init(NODE *n, enum node_type type, VALUE a0, VALUE a1, VALUE a2)
{
    n->flags = T_NODE;
    nd_init_type(n, type);
    n->u1.value = a0;
    n->u2.value = a1;
    n->u3.value = a2;
    n->nd_loc.beg_pos.lineno = 0;
    n->nd_loc.beg_pos.column = 0;
    n->nd_loc.end_pos.lineno = 0;
    n->nd_loc.end_pos.column = 0;
    n->node_id = -1;
}

typedef struct node_buffer_elem_struct {
    struct node_buffer_elem_struct *next;
    long len;
    NODE buf[FLEX_ARY_LEN];
} node_buffer_elem_t;

typedef struct {
    long idx, len;
    node_buffer_elem_t *head;
    node_buffer_elem_t *last;
} node_buffer_list_t;

struct node_buffer_struct {
    node_buffer_list_t unmarkable;
    node_buffer_list_t markable;
    struct rb_ast_local_table_link *local_tables;
    VALUE mark_hash;
    // - id (sequence number)
    // - token_type
    // - text of token
    // - location info
    // Array, whose entry is array
    VALUE tokens;
};

static void
init_node_buffer_list(node_buffer_list_t * nb, node_buffer_elem_t *head)
{
    nb->idx = 0;
    nb->len = NODE_BUF_DEFAULT_LEN;
    nb->head = nb->last = head;
    nb->head->len = nb->len;
    nb->head->next = NULL;
}

static node_buffer_t *
rb_node_buffer_new(void)
{
    const size_t bucket_size = offsetof(node_buffer_elem_t, buf) + NODE_BUF_DEFAULT_LEN * sizeof(NODE);
    const size_t alloc_size = sizeof(node_buffer_t) + (bucket_size * 2);
    STATIC_ASSERT(
        integer_overflow,
        offsetof(node_buffer_elem_t, buf) + NODE_BUF_DEFAULT_LEN * sizeof(NODE)
        > sizeof(node_buffer_t) + 2 * sizeof(node_buffer_elem_t));
    node_buffer_t *nb = ruby_xmalloc(alloc_size);
    init_node_buffer_list(&nb->unmarkable, (node_buffer_elem_t*)&nb[1]);
    init_node_buffer_list(&nb->markable, (node_buffer_elem_t*)((size_t)nb->unmarkable.head + bucket_size));
    nb->local_tables = 0;
    nb->mark_hash = Qnil;
    nb->tokens = Qnil;
    return nb;
}

static void
node_buffer_list_free(node_buffer_list_t * nb)
{
    node_buffer_elem_t *nbe = nb->head;

    while (nbe != nb->last) {
        void *buf = nbe;
        nbe = nbe->next;
        xfree(buf);
    }
}

struct rb_ast_local_table_link {
    struct rb_ast_local_table_link *next;
    // struct rb_ast_id_table {
    int size;
    ID ids[FLEX_ARY_LEN];
    // }
};

static void
rb_node_buffer_free(node_buffer_t *nb)
{
    node_buffer_list_free(&nb->unmarkable);
    node_buffer_list_free(&nb->markable);
    struct rb_ast_local_table_link *local_table = nb->local_tables;
    while (local_table) {
        struct rb_ast_local_table_link *next_table = local_table->next;
        xfree(local_table);
        local_table = next_table;
    }
    xfree(nb);
}

static NODE *
ast_newnode_in_bucket(node_buffer_list_t *nb)
{
    if (nb->idx >= nb->len) {
        long n = nb->len * 2;
        node_buffer_elem_t *nbe;
        nbe = rb_xmalloc_mul_add(n, sizeof(NODE), offsetof(node_buffer_elem_t, buf));
        nbe->len = n;
        nb->idx = 0;
        nb->len = n;
        nbe->next = nb->head;
        nb->head = nbe;
    }
    return &nb->head->buf[nb->idx++];
}

RBIMPL_ATTR_PURE()
static bool
nodetype_markable_p(enum node_type type)
{
    switch (type) {
      case NODE_MATCH:
      case NODE_LIT:
      case NODE_STR:
      case NODE_XSTR:
      case NODE_DSTR:
      case NODE_DXSTR:
      case NODE_DREGX:
      case NODE_DSYM:
      case NODE_ARGS:
      case NODE_ARYPTN:
      case NODE_FNDPTN:
        return true;
      default:
        return false;
    }
}

NODE *
rb_ast_newnode(rb_ast_t *ast, enum node_type type)
{
    node_buffer_t *nb = ast->node_buffer;
    node_buffer_list_t *bucket =
        (nodetype_markable_p(type) ? &nb->markable : &nb->unmarkable);
    return ast_newnode_in_bucket(bucket);
}

void
rb_ast_node_type_change(NODE *n, enum node_type type)
{
    enum node_type old_type = nd_type(n);
    if (nodetype_markable_p(old_type) != nodetype_markable_p(type)) {
        rb_bug("node type changed: %s -> %s",
               ruby_node_name(old_type), ruby_node_name(type));
    }
}

rb_ast_id_table_t *
rb_ast_new_local_table(rb_ast_t *ast, int size)
{
    size_t alloc_size = sizeof(struct rb_ast_local_table_link) + size * sizeof(ID);
    struct rb_ast_local_table_link *link = ruby_xmalloc(alloc_size);
    link->next = ast->node_buffer->local_tables;
    ast->node_buffer->local_tables = link;
    link->size = size;

    return (rb_ast_id_table_t *) &link->size;
}

rb_ast_id_table_t *
rb_ast_resize_latest_local_table(rb_ast_t *ast, int size)
{
    struct rb_ast_local_table_link *link = ast->node_buffer->local_tables;
    size_t alloc_size = sizeof(struct rb_ast_local_table_link) + size * sizeof(ID);
    link = ruby_xrealloc(link, alloc_size);
    ast->node_buffer->local_tables = link;
    link->size = size;

    return (rb_ast_id_table_t *) &link->size;
}

void
rb_ast_delete_node(rb_ast_t *ast, NODE *n)
{
    (void)ast;
    (void)n;
    /* should we implement freelist? */
}

rb_ast_t *
rb_ast_new(void)
{
    node_buffer_t *nb = rb_node_buffer_new();
    rb_ast_t *ast = (rb_ast_t *)rb_imemo_new(imemo_ast, 0, 0, 0, (VALUE)nb);
    return ast;
}

typedef void node_itr_t(void *ctx, NODE * node);

static void
iterate_buffer_elements(node_buffer_elem_t *nbe, long len, node_itr_t *func, void *ctx)
{
    long cursor;
    for (cursor = 0; cursor < len; cursor++) {
        func(ctx, &nbe->buf[cursor]);
    }
}

static void
iterate_node_values(node_buffer_list_t *nb, node_itr_t * func, void *ctx)
{
    node_buffer_elem_t *nbe = nb->head;

    /* iterate over the head first because it's not full */
    iterate_buffer_elements(nbe, nb->idx, func, ctx);

    nbe = nbe->next;
    while (nbe) {
        iterate_buffer_elements(nbe, nbe->len, func, ctx);
        nbe = nbe->next;
    }
}

static void
mark_ast_value(void *ctx, NODE * node)
{
    switch (nd_type(node)) {
      case NODE_ARGS:
        {
            struct rb_args_info *args = node->nd_ainfo;
            rb_gc_mark_movable(args->imemo);
            break;
        }
      case NODE_MATCH:
      case NODE_LIT:
      case NODE_STR:
      case NODE_XSTR:
      case NODE_DSTR:
      case NODE_DXSTR:
      case NODE_DREGX:
      case NODE_DSYM:
        rb_gc_mark_movable(node->nd_lit);
        break;
      case NODE_ARYPTN:
      case NODE_FNDPTN:
        rb_gc_mark_movable(node->nd_rval);
        break;
      default:
        rb_bug("unreachable node %s", ruby_node_name(nd_type(node)));
    }
}

static void
update_ast_value(void *ctx, NODE * node)
{
    switch (nd_type(node)) {
      case NODE_ARGS:
        {
            struct rb_args_info *args = node->nd_ainfo;
            args->imemo = rb_gc_location(args->imemo);
            break;
        }
      case NODE_MATCH:
      case NODE_LIT:
      case NODE_STR:
      case NODE_XSTR:
      case NODE_DSTR:
      case NODE_DXSTR:
      case NODE_DREGX:
      case NODE_DSYM:
        node->nd_lit = rb_gc_location(node->nd_lit);
        break;
      case NODE_ARYPTN:
      case NODE_FNDPTN:
        node->nd_rval = rb_gc_location(node->nd_rval);
        break;
      default:
        rb_bug("unreachable");
    }
}

void
rb_ast_update_references(rb_ast_t *ast)
{
    if (ast->node_buffer) {
        node_buffer_t *nb = ast->node_buffer;

        iterate_node_values(&nb->markable, update_ast_value, NULL);
    }
}

void
rb_ast_mark(rb_ast_t *ast)
{
    if (ast->node_buffer) {
        rb_gc_mark(ast->node_buffer->mark_hash);
        rb_gc_mark(ast->node_buffer->tokens);
    }
    if (ast->body.compile_option) rb_gc_mark(ast->body.compile_option);
    if (ast->node_buffer) {
        node_buffer_t *nb = ast->node_buffer;

        iterate_node_values(&nb->markable, mark_ast_value, NULL);
    }
    if (ast->body.script_lines) rb_gc_mark(ast->body.script_lines);
}

void
rb_ast_free(rb_ast_t *ast)
{
    if (ast->node_buffer) {
        rb_node_buffer_free(ast->node_buffer);
        ast->node_buffer = 0;
    }
}

static size_t
buffer_list_size(node_buffer_list_t *nb)
{
    size_t size = 0;
    node_buffer_elem_t *nbe = nb->head;
    while (nbe != nb->last) {
        nbe = nbe->next;
        size += offsetof(node_buffer_elem_t, buf) + nb->len * sizeof(NODE);
    }
    return size;
}

size_t
rb_ast_memsize(const rb_ast_t *ast)
{
    size_t size = 0;
    node_buffer_t *nb = ast->node_buffer;

    if (nb) {
        size += sizeof(node_buffer_t) + offsetof(node_buffer_elem_t, buf) + NODE_BUF_DEFAULT_LEN * sizeof(NODE);
        size += buffer_list_size(&nb->unmarkable);
        size += buffer_list_size(&nb->markable);
    }
    return size;
}

void
rb_ast_dispose(rb_ast_t *ast)
{
    rb_ast_free(ast);
}

void
rb_ast_add_mark_object(rb_ast_t *ast, VALUE obj)
{
    if (NIL_P(ast->node_buffer->mark_hash)) {
        RB_OBJ_WRITE(ast, &ast->node_buffer->mark_hash, rb_ident_hash_new());
    }
    rb_hash_aset(ast->node_buffer->mark_hash, obj, Qtrue);
}

VALUE
rb_ast_tokens(rb_ast_t *ast)
{
    return ast->node_buffer->tokens;
}

void
rb_ast_set_tokens(rb_ast_t *ast, VALUE tokens)
{
    RB_OBJ_WRITE(ast, &ast->node_buffer->tokens, tokens);
}