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

  proc.c - Proc, Binding, Env

  $Author: mame $
  created at: Wed Jan 17 12:13:14 2007

  Copyright (C) 2004-2007 Koichi Sasada

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

#include "eval_intern.h"
#include "gc.h"

struct METHOD {
    VALUE recv;
    VALUE rclass;
    ID id;
    rb_method_entry_t me;
};

VALUE rb_cUnboundMethod;
VALUE rb_cMethod;
VALUE rb_cBinding;
VALUE rb_cProc;

VALUE rb_iseq_parameters(const rb_iseq_t *iseq, int is_proc);

static VALUE bmcall(VALUE, VALUE);
static int method_arity(VALUE);
static int rb_obj_is_method(VALUE m);
rb_iseq_t *rb_method_get_iseq(VALUE method);

/* Proc */

#define IS_METHOD_PROC_NODE(node) (nd_type(node) == NODE_IFUNC && (node)->nd_cfnc == bmcall)

static void
proc_free(void *ptr)
{
    RUBY_FREE_ENTER("proc");
    if (ptr) {
	ruby_xfree(ptr);
    }
    RUBY_FREE_LEAVE("proc");
}

static void
proc_mark(void *ptr)
{
    rb_proc_t *proc;
    RUBY_MARK_ENTER("proc");
    if (ptr) {
	proc = ptr;
	RUBY_MARK_UNLESS_NULL(proc->envval);
	RUBY_MARK_UNLESS_NULL(proc->blockprocval);
	RUBY_MARK_UNLESS_NULL(proc->block.proc);
	RUBY_MARK_UNLESS_NULL(proc->block.self);
	if (proc->block.iseq && RUBY_VM_IFUNC_P(proc->block.iseq)) {
	    RUBY_MARK_UNLESS_NULL((VALUE)(proc->block.iseq));
	}
    }
    RUBY_MARK_LEAVE("proc");
}

static size_t
proc_memsize(const void *ptr)
{
    return ptr ? sizeof(rb_proc_t) : 0;
}

static const rb_data_type_t proc_data_type = {
    "proc",
    proc_mark,
    proc_free,
    proc_memsize,
};

VALUE
rb_proc_alloc(VALUE klass)
{
    rb_proc_t *proc;
    return TypedData_Make_Struct(klass, rb_proc_t, &proc_data_type, proc);
}

VALUE
rb_obj_is_proc(VALUE proc)
{
    if (rb_typeddata_is_kind_of(proc, &proc_data_type)) {
	return Qtrue;
    }
    else {
	return Qfalse;
    }
}

/* :nodoc: */
static VALUE
proc_dup(VALUE self)
{
    VALUE procval = rb_proc_alloc(rb_cProc);
    rb_proc_t *src, *dst;
    GetProcPtr(self, src);
    GetProcPtr(procval, dst);

    dst->block = src->block;
    dst->block.proc = procval;
    dst->blockprocval = src->blockprocval;
    dst->envval = src->envval;
    dst->safe_level = src->safe_level;
    dst->is_lambda = src->is_lambda;

    return procval;
}

/* :nodoc: */
static VALUE
proc_clone(VALUE self)
{
    VALUE procval = proc_dup(self);
    CLONESETUP(procval, self);
    return procval;
}

/*
 * call-seq:
 *   prc.lambda? -> true or false
 *
 * Returns true for a Proc object which argument handling is rigid.
 * Such procs are typically generated by lambda.
 *
 * A Proc object generated by proc ignore extra arguments.
 *
 *   proc {|a,b| [a,b] }.call(1,2,3)    #=> [1,2]
 *
 * It provides nil for lacked arguments.
 *
 *   proc {|a,b| [a,b] }.call(1)        #=> [1,nil]
 *
 * It expand single-array argument.
 *
 *   proc {|a,b| [a,b] }.call([1,2])    #=> [1,2]
 *
 * A Proc object generated by lambda doesn't have such tricks.
 *
 *   lambda {|a,b| [a,b] }.call(1,2,3)  #=> ArgumentError
 *   lambda {|a,b| [a,b] }.call(1)      #=> ArgumentError
 *   lambda {|a,b| [a,b] }.call([1,2])  #=> ArgumentError
 *
 * Proc#lambda? is a predicate for the tricks.
 * It returns true if no tricks.
 *
 *   lambda {}.lambda?            #=> true
 *   proc {}.lambda?              #=> false
 *
 * Proc.new is same as proc.
 *
 *   Proc.new {}.lambda?          #=> false
 *
 * lambda, proc and Proc.new preserves the tricks of
 * a Proc object given by & argument.
 *
 *   lambda(&lambda {}).lambda?   #=> true
 *   proc(&lambda {}).lambda?     #=> true
 *   Proc.new(&lambda {}).lambda? #=> true
 *
 *   lambda(&proc {}).lambda?     #=> false
 *   proc(&proc {}).lambda?       #=> false
 *   Proc.new(&proc {}).lambda?   #=> false
 *
 * A Proc object generated by & argument has the tricks
 *
 *   def n(&b) b.lambda? end
 *   n {}                         #=> false
 *
 * The & argument preserves the tricks if a Proc object is given
 * by & argument.
 *
 *   n(&lambda {})                #=> true
 *   n(&proc {})                  #=> false
 *   n(&Proc.new {})              #=> false
 *
 * A Proc object converted from a method has no tricks.
 *
 *   def m() end
 *   method(:m).to_proc.lambda?   #=> true
 *
 *   n(&method(:m))               #=> true
 *   n(&method(:m).to_proc)       #=> true
 *
 * define_method is treated same as method definition.
 * The defined method has no tricks.
 *
 *   class C
 *     define_method(:d) {}
 *   end
 *   C.new.e(1,2)       #=> ArgumentError
 *   C.new.method(:d).to_proc.lambda?   #=> true
 *
 * define_method always defines a method without the tricks,
 * even if a non-lambda Proc object is given.
 * This is the only exception which the tricks are not preserved.
 *
 *   class C
 *     define_method(:e, &proc {})
 *   end
 *   C.new.e(1,2)       #=> ArgumentError
 *   C.new.method(:e).to_proc.lambda?   #=> true
 *
 * This exception is for a wrapper of define_method.
 * It eases defining a method defining method which defines a usual method which has no tricks.
 *
 *   class << C
 *     def def2(name, &body)
 *       define_method(name, &body)
 *     end
 *   end
 *   class C
 *     def2(:f) {}
 *   end
 *   C.new.f(1,2)       #=> ArgumentError
 *
 * The wrapper, def2, defines a method which has no tricks.
 *
 */

VALUE
rb_proc_lambda_p(VALUE procval)
{
    rb_proc_t *proc;
    GetProcPtr(procval, proc);

    return proc->is_lambda ? Qtrue : Qfalse;
}

/* Binding */

static void
binding_free(void *ptr)
{
    rb_binding_t *bind;
    RUBY_FREE_ENTER("binding");
    if (ptr) {
	bind = ptr;
	ruby_xfree(ptr);
    }
    RUBY_FREE_LEAVE("binding");
}

static void
binding_mark(void *ptr)
{
    rb_binding_t *bind;
    RUBY_MARK_ENTER("binding");
    if (ptr) {
	bind = ptr;
	RUBY_MARK_UNLESS_NULL(bind->env);
	RUBY_MARK_UNLESS_NULL(bind->filename);
    }
    RUBY_MARK_LEAVE("binding");
}

static size_t
binding_memsize(const void *ptr)
{
    return ptr ? sizeof(rb_binding_t) : 0;
}

static const rb_data_type_t binding_data_type = {
    "binding",
    binding_mark,
    binding_free,
    binding_memsize,
};

static VALUE
binding_alloc(VALUE klass)
{
    VALUE obj;
    rb_binding_t *bind;
    obj = TypedData_Make_Struct(klass, rb_binding_t, &binding_data_type, bind);
    return obj;
}

/* :nodoc: */
static VALUE
binding_dup(VALUE self)
{
    VALUE bindval = binding_alloc(rb_cBinding);
    rb_binding_t *src, *dst;
    GetBindingPtr(self, src);
    GetBindingPtr(bindval, dst);
    dst->env = src->env;
    dst->filename = src->filename;
    dst->line_no = src->line_no;
    return bindval;
}

/* :nodoc: */
static VALUE
binding_clone(VALUE self)
{
    VALUE bindval = binding_dup(self);
    CLONESETUP(bindval, self);
    return bindval;
}

VALUE
rb_binding_new(void)
{
    rb_thread_t *th = GET_THREAD();
    rb_control_frame_t *cfp = rb_vm_get_ruby_level_next_cfp(th, th->cfp);
    VALUE bindval = binding_alloc(rb_cBinding);
    rb_binding_t *bind;

    if (cfp == 0) {
	rb_raise(rb_eRuntimeError, "Can't create Binding Object on top of Fiber.");
    }

    GetBindingPtr(bindval, bind);
    bind->env = rb_vm_make_env_object(th, cfp);
    bind->filename = cfp->iseq->filename;
    bind->line_no = rb_vm_get_sourceline(cfp);
    return bindval;
}

/*
 *  call-seq:
 *     binding -> a_binding
 *
 *  Returns a +Binding+ object, describing the variable and
 *  method bindings at the point of call. This object can be used when
 *  calling +eval+ to execute the evaluated command in this
 *  environment. Also see the description of class +Binding+.
 *
 *     def getBinding(param)
 *       return binding
 *     end
 *     b = getBinding("hello")
 *     eval("param", b)   #=> "hello"
 */

static VALUE
rb_f_binding(VALUE self)
{
    return rb_binding_new();
}

/*
 *  call-seq:
 *     binding.eval(string [, filename [,lineno]])  -> obj
 *
 *  Evaluates the Ruby expression(s) in <em>string</em>, in the
 *  <em>binding</em>'s context.  If the optional <em>filename</em> and
 *  <em>lineno</em> parameters are present, they will be used when
 *  reporting syntax errors.
 *
 *     def getBinding(param)
 *       return binding
 *     end
 *     b = getBinding("hello")
 *     b.eval("param")   #=> "hello"
 */

static VALUE
bind_eval(int argc, VALUE *argv, VALUE bindval)
{
    VALUE args[4];

    rb_scan_args(argc, argv, "12", &args[0], &args[2], &args[3]);
    args[1] = bindval;
    return rb_f_eval(argc+1, args, Qnil /* self will be searched in eval */);
}

static VALUE
proc_new(VALUE klass, int is_lambda)
{
    VALUE procval = Qnil;
    rb_thread_t *th = GET_THREAD();
    rb_control_frame_t *cfp = th->cfp;
    rb_block_t *block;

    if ((GC_GUARDED_PTR_REF(cfp->lfp[0])) != 0) {

	block = GC_GUARDED_PTR_REF(cfp->lfp[0]);
    }
    else {
	cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp);

	if ((GC_GUARDED_PTR_REF(cfp->lfp[0])) != 0) {

	    block = GC_GUARDED_PTR_REF(cfp->lfp[0]);

	    if (is_lambda) {
		rb_warn("tried to create Proc object without a block");
	    }
	}
	else {
	    rb_raise(rb_eArgError,
		     "tried to create Proc object without a block");
	}
    }

    procval = block->proc;

    if (procval) {
	if (RBASIC(procval)->klass == klass) {
	    return procval;
	}
	else {
	    VALUE newprocval = proc_dup(procval);
	    RBASIC(newprocval)->klass = klass;
	    return newprocval;
	}
    }

    procval = rb_vm_make_proc(th, block, klass);

    if (is_lambda) {
	rb_proc_t *proc;
	GetProcPtr(procval, proc);
	proc->is_lambda = TRUE;
    }
    return procval;
}

/*
 *  call-seq:
 *     Proc.new {|...| block } -> a_proc
 *     Proc.new                -> a_proc
 *
 *  Creates a new <code>Proc</code> object, bound to the current
 *  context. <code>Proc::new</code> may be called without a block only
 *  within a method with an attached block, in which case that block is
 *  converted to the <code>Proc</code> object.
 *
 *     def proc_from
 *       Proc.new
 *     end
 *     proc = proc_from { "hello" }
 *     proc.call   #=> "hello"
 */

static VALUE
rb_proc_s_new(int argc, VALUE *argv, VALUE klass)
{
    VALUE block = proc_new(klass, FALSE);

    rb_obj_call_init(block, argc, argv);
    return block;
}

/*
 * call-seq:
 *   proc   { |...| block }  -> a_proc
 *
 * Equivalent to <code>Proc.new</code>.
 */

VALUE
rb_block_proc(void)
{
    return proc_new(rb_cProc, FALSE);
}

VALUE
rb_block_lambda(void)
{
    return proc_new(rb_cProc, TRUE);
}

VALUE
rb_f_lambda(void)
{
    rb_warn("rb_f_lambda() is deprecated; use rb_block_proc() instead");
    return rb_block_lambda();
}

/*
 * call-seq:
 *   lambda { |...| block }  -> a_proc
 *
 * Equivalent to <code>Proc.new</code>, except the resulting Proc objects
 * check the number of parameters passed when called.
 */

static VALUE
proc_lambda(void)
{
    return rb_block_lambda();
}

/* CHECKME: are the argument checking semantics correct? */

/*
 *  call-seq:
 *     prc.call(params,...)   -> obj
 *     prc[params,...]        -> obj
 *     prc.(params,...)       -> obj
 *
 *  Invokes the block, setting the block's parameters to the values in
 *  <i>params</i> using something close to method calling semantics.
 *  Generates a warning if multiple values are passed to a proc that
 *  expects just one (previously this silently converted the parameters
 *  to an array).  Note that prc.() invokes prc.call() with the parameters
 *  given.  It's a syntax sugar to hide "call".
 *
 *  For procs created using <code>Kernel.proc</code>, generates an
 *  error if the wrong number of parameters
 *  are passed to a proc with multiple parameters. For procs created using
 *  <code>Proc.new</code>, extra parameters are silently discarded.
 *
 *  Returns the value of the last expression evaluated in the block. See
 *  also <code>Proc#yield</code>.
 *
 *     a_proc = Proc.new {|a, *b| b.collect {|i| i*a }}
 *     a_proc.call(9, 1, 2, 3)   #=> [9, 18, 27]
 *     a_proc[9, 1, 2, 3]        #=> [9, 18, 27]
 *     a_proc = Proc.new {|a,b| a}
 *     a_proc.call(1,2,3)
 *
 *  <em>produces:</em>
 *
 *     prog.rb:5: wrong number of arguments (3 for 2) (ArgumentError)
 *     	from prog.rb:4:in `call'
 *     	from prog.rb:5
 */

/*
 *  call-seq:
 *     prc === obj   -> result_of_proc
 *
 *  Invokes the block, with <i>obj</i> as the block's parameter.  It is
 *  to allow a proc object to be a target of +when+ clause in the case statement.
 */

static VALUE
proc_call(int argc, VALUE *argv, VALUE procval)
{
    rb_proc_t *proc;
    rb_block_t *blockptr = 0;
    rb_iseq_t *iseq;
    GetProcPtr(procval, proc);

    iseq = proc->block.iseq;
    if (BUILTIN_TYPE(iseq) == T_NODE || iseq->arg_block != -1) {
	if (rb_block_given_p()) {
	    rb_proc_t *proc;
	    VALUE procval;
	    procval = rb_block_proc();
	    GetProcPtr(procval, proc);
	    blockptr = &proc->block;
	}
    }

    return rb_vm_invoke_proc(GET_THREAD(), proc, proc->block.self,
			     argc, argv, blockptr);
}

#if SIZEOF_LONG > SIZEOF_INT
static inline int
check_argc(long argc)
{
    if (argc > INT_MAX || argc < 0) {
	rb_raise(rb_eArgError, "too many arguments (%lu)",
		 (unsigned long)argc);
    }
    return (int)argc;
}
#else
#define check_argc(argc) (argc)
#endif

VALUE
rb_proc_call(VALUE self, VALUE args)
{
    rb_proc_t *proc;
    GetProcPtr(self, proc);
    return rb_vm_invoke_proc(GET_THREAD(), proc, proc->block.self,
			     check_argc(RARRAY_LEN(args)), RARRAY_PTR(args), 0);
}

VALUE
rb_proc_call_with_block(VALUE self, int argc, VALUE *argv, VALUE pass_procval)
{
    rb_proc_t *proc;
    rb_block_t *block = 0;
    GetProcPtr(self, proc);

    if (!NIL_P(pass_procval)) {
	rb_proc_t *pass_proc;
	GetProcPtr(pass_procval, pass_proc);
	block = &pass_proc->block;
    }

    return rb_vm_invoke_proc(GET_THREAD(), proc, proc->block.self,
			     argc, argv, block);
}

/*
 *  call-seq:
 *     prc.arity -> fixnum
 *
 *  Returns the number of arguments that would not be ignored. If the block
 *  is declared to take no arguments, returns 0. If the block is known
 *  to take exactly n arguments, returns n. If the block has optional
 *  arguments, return -n-1, where n is the number of mandatory
 *  arguments. A <code>proc</code> with no argument declarations
 *  is the same a block declaring <code>||</code> as its arguments.
 *
 *     Proc.new {}.arity          #=>  0
 *     Proc.new {||}.arity        #=>  0
 *     Proc.new {|a|}.arity       #=>  1
 *     Proc.new {|a,b|}.arity     #=>  2
 *     Proc.new {|a,b,c|}.arity   #=>  3
 *     Proc.new {|*a|}.arity      #=> -1
 *     Proc.new {|a,*b|}.arity    #=> -2
 *     Proc.new {|a,*b, c|}.arity    #=> -3
 */

static VALUE
proc_arity(VALUE self)
{
    int arity = rb_proc_arity(self);
    return INT2FIX(arity);
}

int
rb_proc_arity(VALUE self)
{
    rb_proc_t *proc;
    rb_iseq_t *iseq;
    GetProcPtr(self, proc);
    iseq = proc->block.iseq;
    if (iseq) {
	if (BUILTIN_TYPE(iseq) != T_NODE) {
	    if (iseq->arg_rest < 0) {
		return iseq->argc;
	    }
	    else {
		return -(iseq->argc + 1 + iseq->arg_post_len);
	    }
	}
	else {
	    NODE *node = (NODE *)iseq;
	    if (IS_METHOD_PROC_NODE(node)) {
		/* method(:foo).to_proc.arity */
		return method_arity(node->nd_tval);
	    }
	}
    }
    return -1;
}

#define get_proc_iseq rb_proc_get_iseq

rb_iseq_t *
rb_proc_get_iseq(VALUE self, int *is_proc)
{
    rb_proc_t *proc;
    rb_iseq_t *iseq;

    GetProcPtr(self, proc);
    iseq = proc->block.iseq;
    if (is_proc) *is_proc = !proc->is_lambda;
    if (!RUBY_VM_NORMAL_ISEQ_P(iseq)) {
	NODE *node = (NODE *)iseq;
	iseq = 0;
	if (IS_METHOD_PROC_NODE(node)) {
	    /* method(:foo).to_proc */
	    iseq = rb_method_get_iseq(node->nd_tval);
	    if (is_proc) *is_proc = 0;
	}
    }
    return iseq;
}

static VALUE
iseq_location(rb_iseq_t *iseq)
{
    VALUE loc[2];

    if (!iseq) return Qnil;
    loc[0] = iseq->filename;
    if (iseq->insn_info_table) {
	loc[1] = INT2FIX(rb_iseq_first_lineno(iseq));
    }
    else {
	loc[1] = Qnil;
    }
    return rb_ary_new4(2, loc);
}

/*
 * call-seq:
 *    prc.source_location  -> [String, Fixnum]
 *
 * returns the ruby source filename and line number containing this proc
 * or nil if this proc was not defined in ruby (i.e. native)
 */

VALUE
rb_proc_location(VALUE self)
{
    return iseq_location(get_proc_iseq(self, 0));
}

static VALUE
unnamed_parameters(int arity)
{
    VALUE a, param = rb_ary_new2((arity < 0) ? -arity : arity);
    int n = (arity < 0) ? ~arity : arity;
    ID req, rest;
    CONST_ID(req, "req");
    a = rb_ary_new3(1, ID2SYM(req));
    OBJ_FREEZE(a);
    for (; n; --n) {
	rb_ary_push(param, a);
    }
    if (arity < 0) {
	CONST_ID(rest, "rest");
	rb_ary_store(param, ~arity, rb_ary_new3(1, ID2SYM(rest)));
    }
    return param;
}

/*
 * call-seq:
 *    proc.parameters  -> array
 *
 * returns the parameter information of this proc.
 *
 *    prc = lambda{|x, y=42, *rest|}
 *    prc.parameters  #=> [[:req, :x], [:opt, :y], [:rest, :rest]]
 */

static VALUE
rb_proc_parameters(VALUE self)
{
    int is_proc;
    rb_iseq_t *iseq = get_proc_iseq(self, &is_proc);
    if (!iseq) {
	return unnamed_parameters(rb_proc_arity(self));
    }
    return rb_iseq_parameters(iseq, is_proc);
}

/*
 * call-seq:
 *   prc == other_proc   ->  true or false
 *
 * Return <code>true</code> if <i>prc</i> is the same object as
 * <i>other_proc</i>, or if they are both procs with the same body.
 */

static VALUE
proc_eq(VALUE self, VALUE other)
{
    if (self == other) {
	return Qtrue;
    }
    else {
	if (rb_obj_is_proc(other)) {
	    rb_proc_t *p1, *p2;
	    GetProcPtr(self, p1);
	    GetProcPtr(other, p2);
	    if (p1->envval == p2->envval &&
		p1->block.iseq->iseq_size == p2->block.iseq->iseq_size &&
		p1->block.iseq->local_size == p2->block.iseq->local_size &&
		MEMCMP(p1->block.iseq->iseq, p2->block.iseq->iseq, VALUE,
		       p1->block.iseq->iseq_size) == 0) {
		return Qtrue;
	    }
	}
    }
    return Qfalse;
}

/*
 * call-seq:
 *   prc.hash   ->  integer
 *
 * Return hash value corresponding to proc body.
 */

static VALUE
proc_hash(VALUE self)
{
    st_index_t hash;
    rb_proc_t *proc;
    GetProcPtr(self, proc);
    hash = rb_hash_start((st_index_t)proc->block.iseq);
    hash = rb_hash_uint(hash, (st_index_t)proc->envval);
    hash = rb_hash_uint(hash, (st_index_t)proc->block.lfp >> 16);
    hash = rb_hash_end(hash);
    return LONG2FIX(hash);
}

/*
 * call-seq:
 *   prc.to_s   -> string
 *
 * Shows the unique identifier for this proc, along with
 * an indication of where the proc was defined.
 */

static VALUE
proc_to_s(VALUE self)
{
    VALUE str = 0;
    rb_proc_t *proc;
    const char *cname = rb_obj_classname(self);
    rb_iseq_t *iseq;
    const char *is_lambda;

    GetProcPtr(self, proc);
    iseq = proc->block.iseq;
    is_lambda = proc->is_lambda ? " (lambda)" : "";

    if (RUBY_VM_NORMAL_ISEQ_P(iseq)) {
	int line_no = 0;

	if (iseq->insn_info_table) {
	    line_no = rb_iseq_first_lineno(iseq);
	}
	str = rb_sprintf("#<%s:%p@%s:%d%s>", cname, (void *)self,
			 RSTRING_PTR(iseq->filename),
			 line_no, is_lambda);
    }
    else {
	str = rb_sprintf("#<%s:%p%s>", cname, (void *)proc->block.iseq,
			 is_lambda);
    }

    if (OBJ_TAINTED(self)) {
	OBJ_TAINT(str);
    }
    return str;
}

/*
 *  call-seq:
 *     prc.to_proc -> prc
 *
 *  Part of the protocol for converting objects to <code>Proc</code>
 *  objects. Instances of class <code>Proc</code> simply return
 *  themselves.
 */

static VALUE
proc_to_proc(VALUE self)
{
    return self;
}

static void
bm_mark(void *ptr)
{
    struct METHOD *data = ptr;
    rb_gc_mark(data->rclass);
    rb_gc_mark(data->recv);
    rb_mark_method_entry(&data->me);
}

static void
bm_free(void *ptr)
{
    struct METHOD *data = ptr;
    rb_method_definition_t *def = data->me.def;
    if (def->alias_count == 0)
	xfree(def);
    else if (def->alias_count > 0)
	def->alias_count--;
    xfree(ptr);
}

static size_t
bm_memsize(const void *ptr)
{
    return ptr ? sizeof(struct METHOD) : 0;
}

static const rb_data_type_t method_data_type = {
    "method",
    bm_mark,
    bm_free,
    bm_memsize,
};

static inline int
rb_obj_is_method(VALUE m)
{
    return rb_typeddata_is_kind_of(m, &method_data_type);
}

static VALUE
mnew(VALUE klass, VALUE obj, ID id, VALUE mclass, int scope)
{
    VALUE method;
    VALUE rclass = klass;
    ID rid = id;
    struct METHOD *data;
    rb_method_entry_t *me, meb;
    rb_method_definition_t *def = 0;
    rb_method_flag_t flag = NOEX_UNDEF;

  again:
    me = rb_method_entry(klass, id);
    if (UNDEFINED_METHOD_ENTRY_P(me)) {
	ID rmiss = rb_intern("respond_to_missing?");
	VALUE sym = ID2SYM(id);

	if (obj != Qundef && !rb_method_basic_definition_p(klass, rmiss)) {
	    if (RTEST(rb_funcall(obj, rmiss, 2, sym, scope ? Qfalse : Qtrue))) {
		def = ALLOC(rb_method_definition_t);
		def->type = VM_METHOD_TYPE_MISSING;
		def->original_id = id;
		def->alias_count = 0;

		meb.flag = 0;
		meb.mark = 0;
		meb.called_id = id;
		meb.klass = klass;
		meb.def = def;
		me = &meb;
		def = 0;

		goto gen_method;
	    }
	}
	rb_print_undef(klass, id, 0);
    }
    def = me->def;
    if (flag == NOEX_UNDEF) {
	flag = me->flag;
	if (scope && (flag & NOEX_MASK) != NOEX_PUBLIC) {
	    const char *v = "";
	    switch (flag & NOEX_MASK) {
		case NOEX_PRIVATE: v = "private"; break;
		case NOEX_PROTECTED: v = "protected"; break;
	    }
	    rb_name_error(id, "method `%s' for %s `%s' is %s",
			  rb_id2name(id),
			  (TYPE(klass) == T_MODULE) ? "module" : "class",
			  rb_class2name(klass),
			  v);
	}
    }
    if (def && def->type == VM_METHOD_TYPE_ZSUPER) {
	klass = RCLASS_SUPER(me->klass);
	id = def->original_id;
	goto again;
    }

    klass = me->klass;

    while (rclass != klass &&
	   (FL_TEST(rclass, FL_SINGLETON) || TYPE(rclass) == T_ICLASS)) {
	rclass = RCLASS_SUPER(rclass);
    }

    if (TYPE(klass) == T_ICLASS) {
	klass = RBASIC(klass)->klass;
    }

  gen_method:
    method = TypedData_Make_Struct(mclass, struct METHOD, &method_data_type, data);

    data->recv = obj;
    data->rclass = rclass;
    data->id = rid;
    data->me = *me;
    if (def) def->alias_count++;

    OBJ_INFECT(method, klass);

    return method;
}


/**********************************************************************
 *
 * Document-class : Method
 *
 *  Method objects are created by <code>Object#method</code>, and are
 *  associated with a particular object (not just with a class). They
 *  may be used to invoke the method within the object, and as a block
 *  associated with an iterator. They may also be unbound from one
 *  object (creating an <code>UnboundMethod</code>) and bound to
 *  another.
 *
 *     class Thing
 *       def square(n)
 *         n*n
 *       end
 *     end
 *     thing = Thing.new
 *     meth  = thing.method(:square)
 *
 *     meth.call(9)                 #=> 81
 *     [ 1, 2, 3 ].collect(&meth)   #=> [1, 4, 9]
 *
 */

/*
 * call-seq:
 *   meth == other_meth  -> true or false
 *
 * Two method objects are equal if they are bound to the same
 * object and refer to the same method definition.
 */

static VALUE
method_eq(VALUE method, VALUE other)
{
    struct METHOD *m1, *m2;
    extern int rb_method_entry_eq(rb_method_entry_t *m1, rb_method_entry_t *m2);

    if (!rb_obj_is_method(other))
	return Qfalse;
    if (CLASS_OF(method) != CLASS_OF(other))
	return Qfalse;

    Check_TypedStruct(method, &method_data_type);
    m1 = (struct METHOD *)DATA_PTR(method);
    m2 = (struct METHOD *)DATA_PTR(other);

    if (!rb_method_entry_eq(&m1->me, &m2->me) ||
	m1->rclass != m2->rclass ||
	m1->recv != m2->recv) {
	return Qfalse;
    }

    return Qtrue;
}

/*
 * call-seq:
 *    meth.hash   -> integer
 *
 * Return a hash value corresponding to the method object.
 */

static VALUE
method_hash(VALUE method)
{
    struct METHOD *m;
    st_index_t hash;

    TypedData_Get_Struct(method, struct METHOD, &method_data_type, m);
    hash = rb_hash_start((st_index_t)m->rclass);
    hash = rb_hash_uint(hash, (st_index_t)m->recv);
    hash = rb_hash_uint(hash, (st_index_t)m->me.def);
    hash = rb_hash_end(hash);

    return INT2FIX(hash);
}

/*
 *  call-seq:
 *     meth.unbind    -> unbound_method
 *
 *  Dissociates <i>meth</i> from it's current receiver. The resulting
 *  <code>UnboundMethod</code> can subsequently be bound to a new object
 *  of the same class (see <code>UnboundMethod</code>).
 */

static VALUE
method_unbind(VALUE obj)
{
    VALUE method;
    struct METHOD *orig, *data;

    TypedData_Get_Struct(obj, struct METHOD, &method_data_type, orig);
    method = TypedData_Make_Struct(rb_cUnboundMethod, struct METHOD,
				   &method_data_type, data);
    data->recv = Qundef;
    data->id = orig->id;
    data->me = orig->me;
    if (orig->me.def) orig->me.def->alias_count++;
    data->rclass = orig->rclass;
    OBJ_INFECT(method, obj);

    return method;
}

/*
 *  call-seq:
 *     meth.receiver    -> object
 *
 *  Returns the bound receiver of the method object.
 */

static VALUE
method_receiver(VALUE obj)
{
    struct METHOD *data;

    TypedData_Get_Struct(obj, struct METHOD, &method_data_type, data);
    return data->recv;
}

/*
 *  call-seq:
 *     meth.name    -> symbol
 *
 *  Returns the name of the method.
 */

static VALUE
method_name(VALUE obj)
{
    struct METHOD *data;

    TypedData_Get_Struct(obj, struct METHOD, &method_data_type, data);
    return ID2SYM(data->id);
}

/*
 *  call-seq:
 *     meth.owner    -> class_or_module
 *
 *  Returns the class or module that defines the method.
 */

static VALUE
method_owner(VALUE obj)
{
    struct METHOD *data;

    TypedData_Get_Struct(obj, struct METHOD, &method_data_type, data);
    return data->me.klass;
}

/*
 *  call-seq:
 *     obj.method(sym)    -> method
 *
 *  Looks up the named method as a receiver in <i>obj</i>, returning a
 *  <code>Method</code> object (or raising <code>NameError</code>). The
 *  <code>Method</code> object acts as a closure in <i>obj</i>'s object
 *  instance, so instance variables and the value of <code>self</code>
 *  remain available.
 *
 *     class Demo
 *       def initialize(n)
 *         @iv = n
 *       end
 *       def hello()
 *         "Hello, @iv = #{@iv}"
 *       end
 *     end
 *
 *     k = Demo.new(99)
 *     m = k.method(:hello)
 *     m.call   #=> "Hello, @iv = 99"
 *
 *     l = Demo.new('Fred')
 *     m = l.method("hello")
 *     m.call   #=> "Hello, @iv = Fred"
 */

VALUE
rb_obj_method(VALUE obj, VALUE vid)
{
    return mnew(CLASS_OF(obj), obj, rb_to_id(vid), rb_cMethod, FALSE);
}

/*
 *  call-seq:
 *     obj.public_method(sym)    -> method
 *
 *  Similar to _method_, searches public method only.
 */

VALUE
rb_obj_public_method(VALUE obj, VALUE vid)
{
    return mnew(CLASS_OF(obj), obj, rb_to_id(vid), rb_cMethod, TRUE);
}

/*
 *  call-seq:
 *     mod.instance_method(symbol)   -> unbound_method
 *
 *  Returns an +UnboundMethod+ representing the given
 *  instance method in _mod_.
 *
 *     class Interpreter
 *       def do_a() print "there, "; end
 *       def do_d() print "Hello ";  end
 *       def do_e() print "!\n";     end
 *       def do_v() print "Dave";    end
 *       Dispatcher = {
 *         "a" => instance_method(:do_a),
 *         "d" => instance_method(:do_d),
 *         "e" => instance_method(:do_e),
 *         "v" => instance_method(:do_v)
 *       }
 *       def interpret(string)
 *         string.each_char {|b| Dispatcher[b].bind(self).call }
 *       end
 *     end
 *
 *     interpreter = Interpreter.new
 *     interpreter.interpret('dave')
 *
 *  <em>produces:</em>
 *
 *     Hello there, Dave!
 */

static VALUE
rb_mod_instance_method(VALUE mod, VALUE vid)
{
    return mnew(mod, Qundef, rb_to_id(vid), rb_cUnboundMethod, FALSE);
}

/*
 *  call-seq:
 *     mod.public_instance_method(symbol)   -> unbound_method
 *
 *  Similar to _instance_method_, searches public method only.
 */

static VALUE
rb_mod_public_instance_method(VALUE mod, VALUE vid)
{
    return mnew(mod, Qundef, rb_to_id(vid), rb_cUnboundMethod, TRUE);
}

/*
 *  call-seq:
 *     define_method(symbol, method)     -> new_method
 *     define_method(symbol) { block }   -> proc
 *
 *  Defines an instance method in the receiver. The _method_
 *  parameter can be a +Proc+, a +Method+ or an +UnboundMethod+ object.
 *  If a block is specified, it is used as the method body. This block
 *  is evaluated using <code>instance_eval</code>, a point that is
 *  tricky to demonstrate because <code>define_method</code> is private.
 *  (This is why we resort to the +send+ hack in this example.)
 *
 *     class A
 *       def fred
 *         puts "In Fred"
 *       end
 *       def create_method(name, &block)
 *         self.class.send(:define_method, name, &block)
 *       end
 *       define_method(:wilma) { puts "Charge it!" }
 *     end
 *     class B < A
 *       define_method(:barney, instance_method(:fred))
 *     end
 *     a = B.new
 *     a.barney
 *     a.wilma
 *     a.create_method(:betty) { p self }
 *     a.betty
 *
 *  <em>produces:</em>
 *
 *     In Fred
 *     Charge it!
 *     #<B:0x401b39e8>
 */

static VALUE
rb_mod_define_method(int argc, VALUE *argv, VALUE mod)
{
    ID id;
    VALUE body;
    int noex = NOEX_PUBLIC;

    if (argc == 1) {
	id = rb_to_id(argv[0]);
	body = rb_block_lambda();
    }
    else if (argc == 2) {
	id = rb_to_id(argv[0]);
	body = argv[1];
	if (!rb_obj_is_method(body) && !rb_obj_is_proc(body)) {
	    rb_raise(rb_eTypeError,
		     "wrong argument type %s (expected Proc/Method)",
		     rb_obj_classname(body));
	}
    }
    else {
	rb_raise(rb_eArgError, "wrong number of arguments (%d for 1)", argc);
    }

    if (rb_obj_is_method(body)) {
	struct METHOD *method = (struct METHOD *)DATA_PTR(body);
	VALUE rclass = method->rclass;
	if (rclass != mod && !RTEST(rb_class_inherited_p(mod, rclass))) {
	    if (FL_TEST(rclass, FL_SINGLETON)) {
		rb_raise(rb_eTypeError,
			 "can't bind singleton method to a different class");
	    }
	    else {
		rb_raise(rb_eTypeError,
			 "bind argument must be a subclass of %s",
			 rb_class2name(rclass));
	    }
	}
	rb_method_entry_set(mod, id, &method->me, noex);
    }
    else if (rb_obj_is_proc(body)) {
	rb_proc_t *proc;
	body = proc_dup(body);
	GetProcPtr(body, proc);
	if (BUILTIN_TYPE(proc->block.iseq) != T_NODE) {
	    proc->block.iseq->defined_method_id = id;
	    proc->block.iseq->klass = mod;
	    proc->is_lambda = TRUE;
	    proc->is_from_method = TRUE;
	}
	rb_add_method(mod, id, VM_METHOD_TYPE_BMETHOD, (void *)body, noex);
    }
    else {
	/* type error */
	rb_raise(rb_eTypeError, "wrong argument type (expected Proc/Method)");
    }

    return body;
}

/*
 *  call-seq:
 *     define_singleton_method(symbol, method) -> new_method
 *     define_singleton_method(symbol) { block } -> proc
 *
 *  Defines a singleton method in the receiver. The _method_
 *  parameter can be a +Proc+, a +Method+ or an +UnboundMethod+ object.
 *  If a block is specified, it is used as the method body.
 *
 *     class A
 *       class << self
 *         def class_name
 *           to_s
 *         end
 *       end
 *     end
 *     A.define_singleton_method(:who_am_i) do
 *       "I am: #{class_name}"
 *     end
 *     A.who_am_i   # ==> "I am: A"
 *
 *     guy = "Bob"
 *     guy.define_singleton_method(:hello) { "#{self}: Hello there!" }
 *     guy.hello    #=>  "Bob: Hello there!"
 */

static VALUE
rb_obj_define_method(int argc, VALUE *argv, VALUE obj)
{
    VALUE klass = rb_singleton_class(obj);

    return rb_mod_define_method(argc, argv, klass);
}


/*
 * MISSING: documentation
 */

static VALUE
method_clone(VALUE self)
{
    VALUE clone;
    struct METHOD *orig, *data;

    TypedData_Get_Struct(self, struct METHOD, &method_data_type, orig);
    clone = TypedData_Make_Struct(CLASS_OF(self), struct METHOD, &method_data_type, data);
    CLONESETUP(clone, self);
    *data = *orig;
    if (data->me.def) data->me.def->alias_count++;

    return clone;
}

/*
 *  call-seq:
 *     meth.call(args, ...)    -> obj
 *     meth[args, ...]         -> obj
 *
 *  Invokes the <i>meth</i> with the specified arguments, returning the
 *  method's return value.
 *
 *     m = 12.method("+")
 *     m.call(3)    #=> 15
 *     m.call(20)   #=> 32
 */

VALUE
rb_method_call(int argc, VALUE *argv, VALUE method)
{
    VALUE result = Qnil;	/* OK */
    struct METHOD *data;
    int state;
    volatile int safe = -1;

    TypedData_Get_Struct(method, struct METHOD, &method_data_type, data);
    if (data->recv == Qundef) {
	rb_raise(rb_eTypeError, "can't call unbound method; bind first");
    }
    PUSH_TAG();
    if (OBJ_TAINTED(method)) {
	safe = rb_safe_level();
	if (rb_safe_level() < 4) {
	    rb_set_safe_level_force(4);
	}
    }
    if ((state = EXEC_TAG()) == 0) {
	rb_thread_t *th = GET_THREAD();
	VALUE rb_vm_call(rb_thread_t *th, VALUE recv, VALUE id, int argc, const VALUE *argv,
			 const rb_method_entry_t *me);

	PASS_PASSED_BLOCK_TH(th);
	result = rb_vm_call(th, data->recv, data->id,  argc, argv, &data->me);
    }
    POP_TAG();
    if (safe >= 0)
	rb_set_safe_level_force(safe);
    if (state)
	JUMP_TAG(state);
    return result;
}

/**********************************************************************
 *
 * Document-class: UnboundMethod
 *
 *  Ruby supports two forms of objectified methods. Class
 *  <code>Method</code> is used to represent methods that are associated
 *  with a particular object: these method objects are bound to that
 *  object. Bound method objects for an object can be created using
 *  <code>Object#method</code>.
 *
 *  Ruby also supports unbound methods; methods objects that are not
 *  associated with a particular object. These can be created either by
 *  calling <code>Module#instance_method</code> or by calling
 *  <code>unbind</code> on a bound method object. The result of both of
 *  these is an <code>UnboundMethod</code> object.
 *
 *  Unbound methods can only be called after they are bound to an
 *  object. That object must be be a kind_of? the method's original
 *  class.
 *
 *     class Square
 *       def area
 *         @side * @side
 *       end
 *       def initialize(side)
 *         @side = side
 *       end
 *     end
 *
 *     area_un = Square.instance_method(:area)
 *
 *     s = Square.new(12)
 *     area = area_un.bind(s)
 *     area.call   #=> 144
 *
 *  Unbound methods are a reference to the method at the time it was
 *  objectified: subsequent changes to the underlying class will not
 *  affect the unbound method.
 *
 *     class Test
 *       def test
 *         :original
 *       end
 *     end
 *     um = Test.instance_method(:test)
 *     class Test
 *       def test
 *         :modified
 *       end
 *     end
 *     t = Test.new
 *     t.test            #=> :modified
 *     um.bind(t).call   #=> :original
 *
 */

/*
 *  call-seq:
 *     umeth.bind(obj) -> method
 *
 *  Bind <i>umeth</i> to <i>obj</i>. If <code>Klass</code> was the class
 *  from which <i>umeth</i> was obtained,
 *  <code>obj.kind_of?(Klass)</code> must be true.
 *
 *     class A
 *       def test
 *         puts "In test, class = #{self.class}"
 *       end
 *     end
 *     class B < A
 *     end
 *     class C < B
 *     end
 *
 *
 *     um = B.instance_method(:test)
 *     bm = um.bind(C.new)
 *     bm.call
 *     bm = um.bind(B.new)
 *     bm.call
 *     bm = um.bind(A.new)
 *     bm.call
 *
 *  <em>produces:</em>
 *
 *     In test, class = C
 *     In test, class = B
 *     prog.rb:16:in `bind': bind argument must be an instance of B (TypeError)
 *     	from prog.rb:16
 */

static VALUE
umethod_bind(VALUE method, VALUE recv)
{
    struct METHOD *data, *bound;

    TypedData_Get_Struct(method, struct METHOD, &method_data_type, data);

    if (data->rclass != CLASS_OF(recv) && !rb_obj_is_kind_of(recv, data->rclass)) {
	if (FL_TEST(data->rclass, FL_SINGLETON)) {
	    rb_raise(rb_eTypeError,
		     "singleton method called for a different object");
	}
	else {
	    rb_raise(rb_eTypeError, "bind argument must be an instance of %s",
		     rb_class2name(data->rclass));
	}
    }

    method = TypedData_Make_Struct(rb_cMethod, struct METHOD, &method_data_type, bound);
    *bound = *data;
    if (bound->me.def) bound->me.def->alias_count++;
    bound->recv = recv;
    bound->rclass = CLASS_OF(recv);

    return method;
}

int
rb_method_entry_arity(const rb_method_entry_t *me)
{
    const rb_method_definition_t *def = me->def;
    if (!def) return 0;
    switch (def->type) {
      case VM_METHOD_TYPE_CFUNC:
	if (def->body.cfunc.argc < 0)
	    return -1;
	return check_argc(def->body.cfunc.argc);
      case VM_METHOD_TYPE_ZSUPER:
	return -1;
      case VM_METHOD_TYPE_ATTRSET:
	return 1;
      case VM_METHOD_TYPE_IVAR:
	return 0;
      case VM_METHOD_TYPE_BMETHOD:
	return rb_proc_arity(def->body.proc);
      case VM_METHOD_TYPE_ISEQ: {
	rb_iseq_t *iseq = def->body.iseq;
	if (iseq->arg_rest == -1 && iseq->arg_opts == 0) {
	    return iseq->argc;
	}
	else {
	    return -(iseq->argc + 1 + iseq->arg_post_len);
	}
      }
      case VM_METHOD_TYPE_UNDEF:
      case VM_METHOD_TYPE_NOTIMPLEMENTED:
	return 0;
      case VM_METHOD_TYPE_MISSING:
	return -1;
      case VM_METHOD_TYPE_OPTIMIZED: {
	switch (def->body.optimize_type) {
	  case OPTIMIZED_METHOD_TYPE_SEND:
	    return -1;
	  default:
	    break;
	}
      }
    }
    rb_bug("rb_method_entry_arity: invalid method entry type (%d)", def->type);
}

/*
 *  call-seq:
 *     meth.arity    -> fixnum
 *
 *  Returns an indication of the number of arguments accepted by a
 *  method. Returns a nonnegative integer for methods that take a fixed
 *  number of arguments. For Ruby methods that take a variable number of
 *  arguments, returns -n-1, where n is the number of required
 *  arguments. For methods written in C, returns -1 if the call takes a
 *  variable number of arguments.
 *
 *     class C
 *       def one;    end
 *       def two(a); end
 *       def three(*a);  end
 *       def four(a, b); end
 *       def five(a, b, *c);    end
 *       def six(a, b, *c, &d); end
 *     end
 *     c = C.new
 *     c.method(:one).arity     #=> 0
 *     c.method(:two).arity     #=> 1
 *     c.method(:three).arity   #=> -1
 *     c.method(:four).arity    #=> 2
 *     c.method(:five).arity    #=> -3
 *     c.method(:six).arity     #=> -3
 *
 *     "cat".method(:size).arity      #=> 0
 *     "cat".method(:replace).arity   #=> 1
 *     "cat".method(:squeeze).arity   #=> -1
 *     "cat".method(:count).arity     #=> -1
 */

static VALUE
method_arity_m(VALUE method)
{
    int n = method_arity(method);
    return INT2FIX(n);
}

static int
method_arity(VALUE method)
{
    struct METHOD *data;

    TypedData_Get_Struct(method, struct METHOD, &method_data_type, data);
    return rb_method_entry_arity(&data->me);
}

int
rb_mod_method_arity(VALUE mod, ID id)
{
    rb_method_entry_t *me = rb_method_entry(mod, id);
    return rb_method_entry_arity(me);
}

int
rb_obj_method_arity(VALUE obj, ID id)
{
    return rb_mod_method_arity(CLASS_OF(obj), id);
}

static inline rb_method_definition_t *
method_get_def(VALUE method)
{
    struct METHOD *data;

    TypedData_Get_Struct(method, struct METHOD, &method_data_type, data);
    return data->me.def;
}

static rb_iseq_t *
method_get_iseq(rb_method_definition_t *def)
{
    switch (def->type) {
      case VM_METHOD_TYPE_BMETHOD:
	return get_proc_iseq(def->body.proc, 0);
      case VM_METHOD_TYPE_ISEQ:
	return def->body.iseq;
      default:
	return 0;
    }
}

rb_iseq_t *
rb_method_get_iseq(VALUE method)
{
    return method_get_iseq(method_get_def(method));
}

/*
 * call-seq:
 *    meth.source_location  -> [String, Fixnum]
 *
 * returns the ruby source filename and line number containing this method
 * or nil if this method was not defined in ruby (i.e. native)
 */

VALUE
rb_method_location(VALUE method)
{
    rb_method_definition_t *def = method_get_def(method);
    if (def->type == VM_METHOD_TYPE_ATTRSET || def->type == VM_METHOD_TYPE_IVAR) {
	if (!def->body.attr.location)
	    return Qnil;
	return rb_ary_dup(def->body.attr.location);
    }
    return iseq_location(method_get_iseq(def));
}

/*
 * call-seq:
 *    meth.parameters  -> array
 *
 * returns the parameter information of this method
 */

static VALUE
rb_method_parameters(VALUE method)
{
    rb_iseq_t *iseq = rb_method_get_iseq(method);
    if (!iseq) {
	return unnamed_parameters(method_arity(method));
    }
    return rb_iseq_parameters(iseq, 0);
}

/*
 *  call-seq:
 *   meth.to_s      ->  string
 *   meth.inspect   ->  string
 *
 *  Show the name of the underlying method.
 *
 *    "cat".method(:count).inspect   #=> "#<Method: String#count>"
 */

static VALUE
method_inspect(VALUE method)
{
    struct METHOD *data;
    VALUE str;
    const char *s;
    const char *sharp = "#";

    TypedData_Get_Struct(method, struct METHOD, &method_data_type, data);
    str = rb_str_buf_new2("#<");
    s = rb_obj_classname(method);
    rb_str_buf_cat2(str, s);
    rb_str_buf_cat2(str, ": ");

    if (FL_TEST(data->me.klass, FL_SINGLETON)) {
	VALUE v = rb_iv_get(data->me.klass, "__attached__");

	if (data->recv == Qundef) {
	    rb_str_buf_append(str, rb_inspect(data->me.klass));
	}
	else if (data->recv == v) {
	    rb_str_buf_append(str, rb_inspect(v));
	    sharp = ".";
	}
	else {
	    rb_str_buf_append(str, rb_inspect(data->recv));
	    rb_str_buf_cat2(str, "(");
	    rb_str_buf_append(str, rb_inspect(v));
	    rb_str_buf_cat2(str, ")");
	    sharp = ".";
	}
    }
    else {
	rb_str_buf_cat2(str, rb_class2name(data->rclass));
	if (data->rclass != data->me.klass) {
	    rb_str_buf_cat2(str, "(");
	    rb_str_buf_cat2(str, rb_class2name(data->me.klass));
	    rb_str_buf_cat2(str, ")");
	}
    }
    rb_str_buf_cat2(str, sharp);
    rb_str_append(str, rb_id2str(data->me.def->original_id));
    if (data->me.def->type == VM_METHOD_TYPE_NOTIMPLEMENTED) {
        rb_str_buf_cat2(str, " (not-implemented)");
    }
    rb_str_buf_cat2(str, ">");

    return str;
}

static VALUE
mproc(VALUE method)
{
    return rb_funcall(Qnil, rb_intern("proc"), 0);
}

static VALUE
mlambda(VALUE method)
{
    return rb_funcall(Qnil, rb_intern("lambda"), 0);
}

static VALUE
bmcall(VALUE args, VALUE method)
{
    volatile VALUE a;
    VALUE ret;
    int argc;

    if (CLASS_OF(args) != rb_cArray) {
	args = rb_ary_new3(1, args);
	argc = 1;
    }
    else {
	argc = check_argc(RARRAY_LEN(args));
    }
    ret = rb_method_call(argc, RARRAY_PTR(args), method);
    RB_GC_GUARD(a) = args;
    return ret;
}

VALUE
rb_proc_new(
    VALUE (*func)(ANYARGS), /* VALUE yieldarg[, VALUE procarg] */
    VALUE val)
{
    VALUE procval = rb_iterate(mproc, 0, func, val);
    return procval;
}

/*
 *  call-seq:
 *     meth.to_proc    -> prc
 *
 *  Returns a <code>Proc</code> object corresponding to this method.
 */

static VALUE
method_proc(VALUE method)
{
    VALUE procval;
    rb_proc_t *proc;
    /*
     * class Method
     *   def to_proc
     *     proc{|*args|
     *       self.call(*args)
     *     }
     *   end
     * end
     */
    procval = rb_iterate(mlambda, 0, bmcall, method);
    GetProcPtr(procval, proc);
    proc->is_from_method = 1;
    return procval;
}

/*
 * call_seq:
 *   local_jump_error.exit_value  -> obj
 *
 * Returns the exit value associated with this +LocalJumpError+.
 */
static VALUE
localjump_xvalue(VALUE exc)
{
    return rb_iv_get(exc, "@exit_value");
}

/*
 * call-seq:
 *    local_jump_error.reason   -> symbol
 *
 * The reason this block was terminated:
 * :break, :redo, :retry, :next, :return, or :noreason.
 */

static VALUE
localjump_reason(VALUE exc)
{
    return rb_iv_get(exc, "@reason");
}

/*
 *  call-seq:
 *     prc.binding    -> binding
 *
 *  Returns the binding associated with <i>prc</i>. Note that
 *  <code>Kernel#eval</code> accepts either a <code>Proc</code> or a
 *  <code>Binding</code> object as its second parameter.
 *
 *     def fred(param)
 *       proc {}
 *     end
 *
 *     b = fred(99)
 *     eval("param", b.binding)   #=> 99
 */
static VALUE
proc_binding(VALUE self)
{
    rb_proc_t *proc;
    VALUE bindval;
    rb_binding_t *bind;

    GetProcPtr(self, proc);
    if (TYPE(proc->block.iseq) == T_NODE) {
	if (!IS_METHOD_PROC_NODE((NODE *)proc->block.iseq)) {
	    rb_raise(rb_eArgError, "Can't create Binding from C level Proc");
	}
    }

    bindval = binding_alloc(rb_cBinding);
    GetBindingPtr(bindval, bind);
    bind->env = proc->envval;
    if (RUBY_VM_NORMAL_ISEQ_P(proc->block.iseq)) {
	bind->filename = proc->block.iseq->filename;
	bind->line_no = rb_iseq_first_lineno(proc->block.iseq);
    }
    else {
	bind->filename = Qnil;
	bind->line_no = 0;
    }
    return bindval;
}

static VALUE curry(VALUE dummy, VALUE args, int argc, VALUE *argv, VALUE passed_proc);

static VALUE
make_curry_proc(VALUE proc, VALUE passed, VALUE arity)
{
    VALUE args = rb_ary_new3(3, proc, passed, arity);
    rb_proc_t *procp;
    int is_lambda;

    GetProcPtr(proc, procp);
    is_lambda = procp->is_lambda;
    rb_ary_freeze(passed);
    rb_ary_freeze(args);
    proc = rb_proc_new(curry, args);
    GetProcPtr(proc, procp);
    procp->is_lambda = is_lambda;
    return proc;
}

static VALUE
curry(VALUE dummy, VALUE args, int argc, VALUE *argv, VALUE passed_proc)
{
    VALUE proc, passed, arity;
    proc = RARRAY_PTR(args)[0];
    passed = RARRAY_PTR(args)[1];
    arity = RARRAY_PTR(args)[2];

    passed = rb_ary_plus(passed, rb_ary_new4(argc, argv));
    rb_ary_freeze(passed);

    if (RARRAY_LEN(passed) < FIX2INT(arity)) {
	if (!NIL_P(passed_proc)) {
	    rb_warn("given block not used");
	}
	arity = make_curry_proc(proc, passed, arity);
	return arity;
    }
    else {
	return rb_proc_call_with_block(proc, check_argc(RARRAY_LEN(passed)),
				       RARRAY_PTR(passed), passed_proc);
    }
}

 /*
  *  call-seq:
  *     prc.curry         -> a_proc
  *     prc.curry(arity)  -> a_proc
  *
  *  Returns a curried proc. If the optional <i>arity</i> argument is given,
  *  it determines the number of arguments.
  *  A curried proc receives some arguments. If a sufficient number of
  *  arguments are supplied, it passes the supplied arguments to the original
  *  proc and returns the result. Otherwise, returns another curried proc that
  *  takes the rest of arguments.
  *
  *     b = proc {|x, y, z| (x||0) + (y||0) + (z||0) }
  *     p b.curry[1][2][3]           #=> 6
  *     p b.curry[1, 2][3, 4]        #=> 6
  *     p b.curry(5)[1][2][3][4][5]  #=> 6
  *     p b.curry(5)[1, 2][3, 4][5]  #=> 6
  *     p b.curry(1)[1]              #=> 1
  *
  *     b = proc {|x, y, z, *w| (x||0) + (y||0) + (z||0) + w.inject(0, &:+) }
  *     p b.curry[1][2][3]           #=> 6
  *     p b.curry[1, 2][3, 4]        #=> 10
  *     p b.curry(5)[1][2][3][4][5]  #=> 15
  *     p b.curry(5)[1, 2][3, 4][5]  #=> 15
  *     p b.curry(1)[1]              #=> 1
  *
  *     b = lambda {|x, y, z| (x||0) + (y||0) + (z||0) }
  *     p b.curry[1][2][3]           #=> 6
  *     p b.curry[1, 2][3, 4]        #=> wrong number of arguments (4 for 3)
  *     p b.curry(5)                 #=> wrong number of arguments (5 for 3)
  *     p b.curry(1)                 #=> wrong number of arguments (1 for 3)
  *
  *     b = lambda {|x, y, z, *w| (x||0) + (y||0) + (z||0) + w.inject(0, &:+) }
  *     p b.curry[1][2][3]           #=> 6
  *     p b.curry[1, 2][3, 4]        #=> 10
  *     p b.curry(5)[1][2][3][4][5]  #=> 15
  *     p b.curry(5)[1, 2][3, 4][5]  #=> 15
  *     p b.curry(1)                 #=> wrong number of arguments (1 for 3)
  *
  *     b = proc { :foo }
  *     p b.curry[]                  #=> :foo
  */
static VALUE
proc_curry(int argc, VALUE *argv, VALUE self)
{
    int sarity, marity = rb_proc_arity(self);
    VALUE arity, opt = Qfalse;

    if (marity < 0) {
	marity = -marity - 1;
	opt = Qtrue;
    }

    rb_scan_args(argc, argv, "01", &arity);
    if (NIL_P(arity)) {
	arity = INT2FIX(marity);
    }
    else {
	sarity = FIX2INT(arity);
	if (rb_proc_lambda_p(self) && (sarity < marity || (sarity > marity && !opt))) {
	    rb_raise(rb_eArgError, "wrong number of arguments (%d for %d)", sarity, marity);
	}
    }

    return make_curry_proc(self, rb_ary_new(), arity);
}

/*
 *  Document-class: LocalJumpError
 *
 *  Raised when Ruby can't yield as requested.
 *
 *  A typical scenario is attempting to yield when no block is given:
 *
 *     def call_block
 *       yield 42
 *     end
 *     call_block
 *
 *  <em>raises the exception:</em>
 *
 *     LocalJumpError: no block given (yield)
 *
 *  A more subtle example:
 *
 *     def get_me_a_return
 *       Proc.new { return 42 }
 *     end
 *     get_me_a_return.call
 *
 *  <em>raises the exception:</em>
 *
 *     LocalJumpError: unexpected return
 */

/*
 *  Document-class: SystemStackError
 *
 *  Raised in case of a stack overflow.
 *
 *     def me_myself_and_i
 *       me_myself_and_i
 *     end
 *     me_myself_and_i
 *
 *  <em>raises the exception:</em>
 *
 *    SystemStackError: stack level too deep
 */

/*
 *  <code>Proc</code> objects are blocks of code that have been bound to
 *  a set of local variables. Once bound, the code may be called in
 *  different contexts and still access those variables.
 *
 *     def gen_times(factor)
 *       return Proc.new {|n| n*factor }
 *     end
 *
 *     times3 = gen_times(3)
 *     times5 = gen_times(5)
 *
 *     times3.call(12)               #=> 36
 *     times5.call(5)                #=> 25
 *     times3.call(times5.call(4))   #=> 60
 *
 */

void
Init_Proc(void)
{
    /* Proc */
    rb_cProc = rb_define_class("Proc", rb_cObject);
    rb_undef_alloc_func(rb_cProc);
    rb_define_singleton_method(rb_cProc, "new", rb_proc_s_new, -1);

#if 0 /* incomplete. */
    rb_add_method(rb_cProc, rb_intern("call"), VM_METHOD_TYPE_OPTIMIZED,
		  (void *)OPTIMIZED_METHOD_TYPE_CALL, 0);
    rb_add_method(rb_cProc, rb_intern("[]"), VM_METHOD_TYPE_OPTIMIZED,
		  (void *)OPTIMIZED_METHOD_TYPE_CALL, 0);
    rb_add_method(rb_cProc, rb_intern("==="), VM_METHOD_TYPE_OPTIMIZED,
		  (void *)OPTIMIZED_METHOD_TYPE_CALL, 0);
    rb_add_method(rb_cProc, rb_intern("yield"), VM_METHOD_TYPE_OPTIMIZED,
		  (void *)OPTIMIZED_METHOD_TYPE_CALL, 0);
#else
    rb_define_method(rb_cProc, "call", proc_call, -1);
    rb_define_method(rb_cProc, "[]", proc_call, -1);
    rb_define_method(rb_cProc, "===", proc_call, -1);
    rb_define_method(rb_cProc, "yield", proc_call, -1);
#endif
    rb_define_method(rb_cProc, "to_proc", proc_to_proc, 0);
    rb_define_method(rb_cProc, "arity", proc_arity, 0);
    rb_define_method(rb_cProc, "clone", proc_clone, 0);
    rb_define_method(rb_cProc, "dup", proc_dup, 0);
    rb_define_method(rb_cProc, "==", proc_eq, 1);
    rb_define_method(rb_cProc, "eql?", proc_eq, 1);
    rb_define_method(rb_cProc, "hash", proc_hash, 0);
    rb_define_method(rb_cProc, "to_s", proc_to_s, 0);
    rb_define_method(rb_cProc, "lambda?", rb_proc_lambda_p, 0);
    rb_define_method(rb_cProc, "binding", proc_binding, 0);
    rb_define_method(rb_cProc, "curry", proc_curry, -1);
    rb_define_method(rb_cProc, "source_location", rb_proc_location, 0);
    rb_define_method(rb_cProc, "parameters", rb_proc_parameters, 0);

    /* Exceptions */
    rb_eLocalJumpError = rb_define_class("LocalJumpError", rb_eStandardError);
    rb_define_method(rb_eLocalJumpError, "exit_value", localjump_xvalue, 0);
    rb_define_method(rb_eLocalJumpError, "reason", localjump_reason, 0);

    rb_eSysStackError = rb_define_class("SystemStackError", rb_eException);
    sysstack_error = rb_exc_new3(rb_eSysStackError,
				 rb_obj_freeze(rb_str_new2("stack level too deep")));
    OBJ_TAINT(sysstack_error);

    /* utility functions */
    rb_define_global_function("proc", rb_block_proc, 0);
    rb_define_global_function("lambda", proc_lambda, 0);

    /* Method */
    rb_cMethod = rb_define_class("Method", rb_cObject);
    rb_undef_alloc_func(rb_cMethod);
    rb_undef_method(CLASS_OF(rb_cMethod), "new");
    rb_define_method(rb_cMethod, "==", method_eq, 1);
    rb_define_method(rb_cMethod, "eql?", method_eq, 1);
    rb_define_method(rb_cMethod, "hash", method_hash, 0);
    rb_define_method(rb_cMethod, "clone", method_clone, 0);
    rb_define_method(rb_cMethod, "call", rb_method_call, -1);
    rb_define_method(rb_cMethod, "[]", rb_method_call, -1);
    rb_define_method(rb_cMethod, "arity", method_arity_m, 0);
    rb_define_method(rb_cMethod, "inspect", method_inspect, 0);
    rb_define_method(rb_cMethod, "to_s", method_inspect, 0);
    rb_define_method(rb_cMethod, "to_proc", method_proc, 0);
    rb_define_method(rb_cMethod, "receiver", method_receiver, 0);
    rb_define_method(rb_cMethod, "name", method_name, 0);
    rb_define_method(rb_cMethod, "owner", method_owner, 0);
    rb_define_method(rb_cMethod, "unbind", method_unbind, 0);
    rb_define_method(rb_cMethod, "source_location", rb_method_location, 0);
    rb_define_method(rb_cMethod, "parameters", rb_method_parameters, 0);
    rb_define_method(rb_mKernel, "method", rb_obj_method, 1);
    rb_define_method(rb_mKernel, "public_method", rb_obj_public_method, 1);

    /* UnboundMethod */
    rb_cUnboundMethod = rb_define_class("UnboundMethod", rb_cObject);
    rb_undef_alloc_func(rb_cUnboundMethod);
    rb_undef_method(CLASS_OF(rb_cUnboundMethod), "new");
    rb_define_method(rb_cUnboundMethod, "==", method_eq, 1);
    rb_define_method(rb_cUnboundMethod, "eql?", method_eq, 1);
    rb_define_method(rb_cUnboundMethod, "hash", method_hash, 0);
    rb_define_method(rb_cUnboundMethod, "clone", method_clone, 0);
    rb_define_method(rb_cUnboundMethod, "arity", method_arity_m, 0);
    rb_define_method(rb_cUnboundMethod, "inspect", method_inspect, 0);
    rb_define_method(rb_cUnboundMethod, "to_s", method_inspect, 0);
    rb_define_method(rb_cUnboundMethod, "name", method_name, 0);
    rb_define_method(rb_cUnboundMethod, "owner", method_owner, 0);
    rb_define_method(rb_cUnboundMethod, "bind", umethod_bind, 1);
    rb_define_method(rb_cUnboundMethod, "source_location", rb_method_location, 0);
    rb_define_method(rb_cUnboundMethod, "parameters", rb_method_parameters, 0);

    /* Module#*_method */
    rb_define_method(rb_cModule, "instance_method", rb_mod_instance_method, 1);
    rb_define_method(rb_cModule, "public_instance_method", rb_mod_public_instance_method, 1);
    rb_define_private_method(rb_cModule, "define_method", rb_mod_define_method, -1);

    /* Kernel */
    rb_define_method(rb_mKernel, "define_singleton_method", rb_obj_define_method, -1);
}

/*
 *  Objects of class <code>Binding</code> encapsulate the execution
 *  context at some particular place in the code and retain this context
 *  for future use. The variables, methods, value of <code>self</code>,
 *  and possibly an iterator block that can be accessed in this context
 *  are all retained. Binding objects can be created using
 *  <code>Kernel#binding</code>, and are made available to the callback
 *  of <code>Kernel#set_trace_func</code>.
 *
 *  These binding objects can be passed as the second argument of the
 *  <code>Kernel#eval</code> method, establishing an environment for the
 *  evaluation.
 *
 *     class Demo
 *       def initialize(n)
 *         @secret = n
 *       end
 *       def getBinding
 *         return binding()
 *       end
 *     end
 *
 *     k1 = Demo.new(99)
 *     b1 = k1.getBinding
 *     k2 = Demo.new(-3)
 *     b2 = k2.getBinding
 *
 *     eval("@secret", b1)   #=> 99
 *     eval("@secret", b2)   #=> -3
 *     eval("@secret")       #=> nil
 *
 *  Binding objects have no class-specific methods.
 *
 */

void
Init_Binding(void)
{
    rb_cBinding = rb_define_class("Binding", rb_cObject);
    rb_undef_alloc_func(rb_cBinding);
    rb_undef_method(CLASS_OF(rb_cBinding), "new");
    rb_define_method(rb_cBinding, "clone", binding_clone, 0);
    rb_define_method(rb_cBinding, "dup", binding_dup, 0);
    rb_define_method(rb_cBinding, "eval", bind_eval, -1);
    rb_define_global_function("binding", rb_f_binding, 0);
}

