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Class: Range

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Instance Chain:
self, ::Enumerable
Inherits: Object
Defined in: range.c

Overview

A Range represents an interval—a set of values with a beginning and an end. Ranges may be constructed using the s..e and s...e literals, or with .new. Ranges constructed using .. run from the beginning to the end inclusively. Those created using ... exclude the end value. When used as an iterator, ranges return each value in the sequence.

(-1..-5).to_a      #=> []
(-5..-1).to_a      #=> [-5, -4, -3, -2, -1]
('a'..'e').to_a    #=> ["a", "b", "c", "d", "e"]
('a'...'e').to_a   #=> ["a", "b", "c", "d"]

Custom Objects in Ranges

Ranges can be constructed using any objects that can be compared using the <=> operator. Methods that treat the range as a sequence (#each and methods inherited from ::Enumerable) expect the begin object to implement a succ method to return the next object in sequence. The #step and #include? methods require the begin object to implement succ or to be numeric.

In the Xs class below both <=> and succ are implemented so Xs can be used to construct ranges. Note that the ::Comparable module is included so the #== method is defined in terms of <=>.

class Xs                # represent a string of 'x's
  include Comparable
  attr :length
  def initialize(n)
    @length = n
  end
  def succ
    Xs.new(@length + 1)
  end
  def <=>(other)
    @length <=> other.length
  end
  def to_s
    sprintf "%2d #{inspect}", @length
  end
  def inspect
    'x' * @length
  end
end

An example of using Xs to construct a range:

r = Xs.new(3)..Xs.new(6)   #=> xxx..xxxxxx
r.to_a                     #=> [xxx, xxxx, xxxxx, xxxxxx]
r.member?(Xs.new(5))       #=> true

Class Method Summary

Instance Attribute Summary

Instance Method Summary

::Enumerable - Included

#all?

Passes each element of the collection to the given block.
#any?

Passes each element of the collection to the given block.
#chunk

Enumerates over the items, chunking them together based on the return value of the block.
#chunk_while

Creates an enumerator for each chunked elements.
#collect

Alias for Enumerable#map.
#collect_concat

Alias for Enumerable#flat_map.
#count

Returns the number of items in enum through enumeration.
#cycle

Calls block for each element of enum repeatedly n times or forever if none or nil is given.
#detect

Alias for Enumerable#find.
#drop

Drops first n elements from enum, and returns rest elements in an array.
#drop_while

Drops elements up to, but not including, the first element for which the block returns nil or false and returns an array containing the remaining elements.
#each_cons

Iterates the given block for each array of consecutive <n> elements.
#each_entry

Calls block once for each element in self, passing that element as a parameter, converting multiple values from yield to an array.
#each_slice

Iterates the given block for each slice of <n> elements.
#each_with_index

Calls block with two arguments, the item and its index, for each item in enum.
#each_with_object

Iterates the given block for each element with an arbitrary object given, and returns the initially given object.
#entries

Alias for Enumerable#to_a.
#find

Passes each entry in enum to block.
#find_all

Alias for Enumerable#select.
#find_index

Compares each entry in enum with value or passes to block.
#first

Returns the first element, or the first n elements, of the enumerable.
#flat_map

Returns a new array with the concatenated results of running block once for every element in enum.
#grep

Returns an array of every element in enum for which Pattern === element.
#grep_v

Inverted version of Enumerable#grep.
#group_by

Groups the collection by result of the block.
#include?

Alias for Enumerable#member?.
#inject

Combines all elements of enum by applying a binary operation, specified by a block or a symbol that names a method or operator.
#lazy

Returns a lazy enumerator, whose methods map/collect, flat_map/collect_concat, select/find_all, reject, grep, grep_v, zip, take, take_while, drop, and drop_while enumerate values only on an as-needed basis.
#map

Returns a new array with the results of running block once for every element in enum.
#max

Returns the object in enum with the maximum value.
#max_by

Returns the object in enum that gives the maximum value from the given block.
#member?

Returns true if any member of enum equals obj.
#min

Returns the object in enum with the minimum value.
#min_by

Returns the object in enum that gives the minimum value from the given block.
#minmax

Returns a two element array which contains the minimum and the maximum value in the enumerable.
#minmax_by

Returns a two element array containing the objects in enum that correspond to the minimum and maximum values respectively from the given block.
#none?

Passes each element of the collection to the given block.
#one?

Passes each element of the collection to the given block.
#partition

Returns two arrays, the first containing the elements of enum for which the block evaluates to true, the second containing the rest.
#reduce

Alias for Enumerable#inject.
#reject

Returns an array for all elements of enum for which the given block returns false.
#reverse_each

Builds a temporary array and traverses that array in reverse order.
#select

Returns an array containing all elements of enum for which the given block returns a true value.
#slice_after

Creates an enumerator for each chunked elements.
#slice_before

Creates an enumerator for each chunked elements.
#slice_when

Creates an enumerator for each chunked elements.
#sort

Returns an array containing the items in enum sorted.
#sort_by

Sorts enum using a set of keys generated by mapping the values in enum through the given block.
#sum

Returns the sum of elements in an ::Enumerable.
#take

Returns first n elements from enum.
#take_while

Passes elements to the block until the block returns nil or false, then stops iterating and returns an array of all prior elements.
#to_a

Returns an array containing the items in enum.
#to_h

Returns the result of interpreting enum as a list of [key, value] pairs.
#uniq

Returns a new array by removing duplicate values in self.
#zip

Takes one element from enum and merges corresponding elements from each args.

Constructor Details

.new(begin, end, exclude_end=false) ⇒ Range

Constructs a range using the given #begin and #end. If the exclude_end parameter is omitted or is false, the rng will include the end object; otherwise, it will be excluded.

[ GitHub ] 

  


# File 'range.c', line 81



static VALUE
range_initialize(int argc, VALUE *argv, VALUE range)
{
    VALUE beg, end, flags;

    rb_scan_args(argc, argv, "21", &beg, &end, &flags);
    range_modify(range);
    range_init(range, beg, end, RBOOL(RTEST(flags)));
    return Qnil;
}


  







Instance Attribute Details



  

    #exclude_end?  ⇒ Boolean  (readonly)  



  

    

Returns true if the range excludes its end value.



(1..5).exclude_end?     #=> false
(1...5).exclude_end?    #=> true


  



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# File 'range.c', line 111



static VALUE
range_exclude_end_p(VALUE range)
{
    return EXCL(range) ? Qtrue : Qfalse;
}


  







Instance Method Details



  

    #==(obj)  ⇒ Boolean   



  

    

Returns true only if obj is a Range, has equivalent begin and end items (by comparing them with ==), and has the same #exclude_end? setting as the range.



(0..2) == (0..2)            #=> true
(0..2) == Range.new(0,2)    #=> true
(0..2) == (0...2)           #=> false


  



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# File 'range.c', line 146



static VALUE
range_eq(VALUE range, VALUE obj)
{
    if (range == obj)
	return Qtrue;
    if (!rb_obj_is_kind_of(obj, rb_cRange))
	return Qfalse;

    return rb_exec_recursive_paired(recursive_equal, range, obj, obj);
}


  








  

    #===(obj)  ⇒ Boolean   



  

    

Returns true if obj is an element of the range, false otherwise.  Conveniently, === is the comparison operator used by case statements.



case 79
when 1..50   then   print "low\n"
when 51..75  then   print "medium\n"
when 76..100 then   print "high\n"
end



produces:



high


  



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# File 'range.c', line 1125



static VALUE
range_eqq(VALUE range, VALUE val)
{
    return rb_funcall(range, rb_intern("include?"), 1, val);
}


  








  

    #begin  ⇒ Object   



  

    

Returns the object that defines the beginning of the range.



(1..10).begin   #=> 1


  



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# File 'range.c', line 796



static VALUE
range_begin(VALUE range)
{
    return RANGE_BEG(range);
}


  








  

    #bsearch {|obj| ... } ⇒ value   



  

    

By using binary search, finds a value in range which meets the given condition in O(log n) where n is the size of the range.



You can use this method in two use cases: a find-minimum mode and a find-any mode.  In either case, the elements of the range must be monotone (or sorted) with respect to the block.



In find-minimum mode (this is a good choice for typical use case), the block must return true or false, and there must be a value x so that:


  • 

    the block returns false for any value which is less than x, and
    

  • 

    the block returns true for any value which is greater than or equal to x.
    




If x is within the range, this method returns the value x. Otherwise, it returns nil.



ary = [0, 4, 7, 10, 12]
(0...ary.size).bsearch {|i| ary[i] >= 4 } #=> 1
(0...ary.size).bsearch {|i| ary[i] >= 6 } #=> 2
(0...ary.size).bsearch {|i| ary[i] >= 8 } #=> 3
(0...ary.size).bsearch {|i| ary[i] >= 100 } #=> nil

(0.0...Float::INFINITY).bsearch {|x| Math.log(x) >= 0 } #=> 1.0



In find-any mode (this behaves like libc's bsearch(3)), the block must return a number, and there must be two values x and y (x <= y) so that:


  • 

    the block returns a positive number for v if v < x,
    

  • 

    the block returns zero for v if x <= v < y, and
    

  • 

    the block returns a negative number for v if y <= v.
    




This method returns any value which is within the intersection of the given range and x…y (if any).  If there is no value that satisfies the condition, it returns nil.



ary = [0, 100, 100, 100, 200]
(0..4).bsearch {|i| 100 - ary[i] } #=> 1, 2 or 3
(0..4).bsearch {|i| 300 - ary[i] } #=> nil
(0..4).bsearch {|i|  50 - ary[i] } #=> nil



You must not mix the two modes at a time; the block must always return either true/false, or always return a number.  It is undefined which value is actually picked up at each iteration.


  



  [ GitHub ]


  

  


# File 'range.c', line 558



static VALUE
range_bsearch(VALUE range)
{
    VALUE beg, end, satisfied = Qnil;
    int smaller;

    /* Implementation notes:
     * Floats are handled by mapping them to 64 bits integers.
     * Apart from sign issues, floats and their 64 bits integer have the
     * same order, assuming they are represented as exponent followed
     * by the mantissa. This is true with or without implicit bit.
     *
     * Finding the average of two ints needs to be careful about
     * potential overflow (since float to long can use 64 bits)
     * as well as the fact that -1/2 can be 0 or -1 in C89.
     *
     * Note that -0.0 is mapped to the same int as 0.0 as we don't want
     * (-1...0.0).bsearch to yield -0.0.
     */

#define BSEARCH_CHECK(expr) \
    do { \
	VALUE val = (expr); \
	VALUE v = rb_yield(val); \
	if (FIXNUM_P(v)) { \
	    if (v == INT2FIX(0)) return val; \
	    smaller = (SIGNED_VALUE)v < 0; \
	} \
	else if (v == Qtrue) { \
	    satisfied = val; \
	    smaller = 1; \
	} \
	else if (v == Qfalse || v == Qnil) { \
	    smaller = 0; \
	} \
	else if (rb_obj_is_kind_of(v, rb_cNumeric)) { \
	    int cmp = rb_cmpint(rb_funcall(v, id_cmp, 1, INT2FIX(0)), v, INT2FIX(0)); \
	    if (!cmp) return val; \
	    smaller = cmp < 0; \
	} \
	else { \
	    rb_raise(rb_eTypeError, "wrong argument type %"PRIsVALUE \
		     " (must be numeric, true, false or nil)", \
		     rb_obj_class(v)); \
	} \
    } while (0)

#define BSEARCH(conv) \
    do { \
	RETURN_ENUMERATOR(range, 0, 0); \
	if (EXCL(range)) high--; \
	org_high = high; \
	while (low < high) { \
	    mid = ((high < 0) == (low < 0)) ? low + ((high - low) / 2) \
		: (low < -high) ? -((-1 - low - high)/2 + 1) : (low + high) / 2; \
	    BSEARCH_CHECK(conv(mid)); \
	    if (smaller) { \
		high = mid; \
	    } \
	    else { \
		low = mid + 1; \
	    } \
	} \
	if (low == org_high) { \
	    BSEARCH_CHECK(conv(low)); \
	    if (!smaller) return Qnil; \
	} \
	return satisfied; \
    } while (0)


    beg = RANGE_BEG(range);
    end = RANGE_END(range);

    if (FIXNUM_P(beg) && FIXNUM_P(end)) {
	long low = FIX2LONG(beg);
	long high = FIX2LONG(end);
	long mid, org_high;
	BSEARCH(INT2FIX);
    }
#if SIZEOF_DOUBLE == 8 && defined(HAVE_INT64_T)
    else if (RB_TYPE_P(beg, T_FLOAT) || RB_TYPE_P(end, T_FLOAT)) {
	int64_t low  = double_as_int64(RFLOAT_VALUE(rb_Float(beg)));
	int64_t high = double_as_int64(RFLOAT_VALUE(rb_Float(end)));
	int64_t mid, org_high;
	BSEARCH(int64_as_double_to_num);
    }
#endif
    else if (is_integer_p(beg) && is_integer_p(end)) {
	VALUE low = rb_to_int(beg);
	VALUE high = rb_to_int(end);
	VALUE mid, org_high;
	RETURN_ENUMERATOR(range, 0, 0);
	if (EXCL(range)) high = rb_funcall(high, '-', 1, INT2FIX(1));
	org_high = high;

	while (rb_cmpint(rb_funcall(low, id_cmp, 1, high), low, high) < 0) {
	    mid = rb_funcall(rb_funcall(high, '+', 1, low), id_div, 1, INT2FIX(2));
	    BSEARCH_CHECK(mid);
	    if (smaller) {
		high = mid;
	    }
	    else {
		low = rb_funcall(mid, '+', 1, INT2FIX(1));
	    }
	}
	if (rb_equal(low, org_high)) {
	    BSEARCH_CHECK(low);
	    if (!smaller) return Qnil;
	}
	return satisfied;
    }
    else {
	rb_raise(rb_eTypeError, "can't do binary search for %s", rb_obj_classname(beg));
    }
    return range;
}


  








  

    #cover?(obj)  ⇒ Boolean   



  

    

Returns true if obj is between the begin and end of the range.



This tests begin <= obj <= end when #exclude_end? is false and begin <= obj < end when #exclude_end? is true.



("a".."z").cover?("c")    #=> true
("a".."z").cover?("5")    #=> false
("a".."z").cover?("cc")   #=> true


  



  [ GitHub ]


  

  


# File 'range.c', line 1183



static VALUE
range_cover(VALUE range, VALUE val)
{
    VALUE beg, end;

    beg = RANGE_BEG(range);
    end = RANGE_END(range);
    return r_cover_p(range, beg, end, val);
}


  








  

    

      #each {|i| ... } ⇒ Range 
      #each  ⇒ Enumerator 
    

  



  

    

Iterates over the elements of range, passing each in turn to the block.



The each method can only be used if the begin object of the range supports the succ method.  A TypeError is raised if the object does not have succ method defined (like ::Float).



If no block is given, an enumerator is returned instead.



(10..15).each {|n| print n, ' ' }
# prints: 10 11 12 13 14 15

(2.5..5).each {|n| print n, ' ' }
# raises: TypeError: can't iterate from Float


  





  


  [ GitHub ]


  

  


# File 'range.c', line 739



static VALUE
range_each(VALUE range)
{
    VALUE beg, end;

    RETURN_SIZED_ENUMERATOR(range, 0, 0, range_enum_size);

    beg = RANGE_BEG(range);
    end = RANGE_END(range);

    if (FIXNUM_P(beg) && FIXNUM_P(end)) { /* fixnums are special */
	long lim = FIX2LONG(end);
	long i;

	if (!EXCL(range))
	    lim += 1;
	for (i = FIX2LONG(beg); i < lim; i++) {
	    rb_yield(LONG2FIX(i));
	}
    }
    else if (SYMBOL_P(beg) && SYMBOL_P(end)) { /* symbols are special */
	VALUE args[2];

	args[0] = rb_sym2str(end);
	args[1] = EXCL(range) ? Qtrue : Qfalse;
	rb_block_call(rb_sym2str(beg), rb_intern("upto"), 2, args, sym_each_i, 0);
    }
    else {
	VALUE tmp = rb_check_string_type(beg);

	if (!NIL_P(tmp)) {
	    VALUE args[2];

	    args[0] = end;
	    args[1] = EXCL(range) ? Qtrue : Qfalse;
	    rb_block_call(tmp, rb_intern("upto"), 2, args, each_i, 0);
	}
	else {
	    if (!discrete_object_p(beg)) {
		rb_raise(rb_eTypeError, "can't iterate from %s",
			 rb_obj_classname(beg));
	    }
	    range_each_func(range, each_i, 0);
	}
    }
    return range;
}


  








  

    #end  ⇒ Object   



  

    

Returns the object that defines the end of the range.



(1..10).end    #=> 10
(1...10).end   #=> 10


  



  [ GitHub ]


  

  


# File 'range.c', line 814



static VALUE
range_end(VALUE range)
{
    return RANGE_END(range);
}


  








  

    #eql?(obj)  ⇒ Boolean   



  

    

Returns true only if obj is a Range, has equivalent begin and end items (by comparing them with eql?), and has the same #exclude_end? setting as the range.



(0..2).eql?(0..2)            #=> true
(0..2).eql?(Range.new(0,2))  #=> true
(0..2).eql?(0...2)           #=> false


  



  [ GitHub ]


  

  


# File 'range.c', line 200



static VALUE
range_eql(VALUE range, VALUE obj)
{
    if (range == obj)
	return Qtrue;
    if (!rb_obj_is_kind_of(obj, rb_cRange))
	return Qfalse;
    return rb_exec_recursive_paired(recursive_eql, range, obj, obj);
}


  








  

    

      #first  ⇒ Object 
      #first(n)  ⇒ Array 
    

  



  

    

Returns the first object in the range, or an array of the first n elements.



(10..20).first     #=> 10
(10..20).first(3)  #=> [10, 11, 12]


  





  


  [ GitHub ]


  

  


# File 'range.c', line 848



static VALUE
range_first(int argc, VALUE *argv, VALUE range)
{
    VALUE n, ary[2];

    if (argc == 0) return RANGE_BEG(range);

    rb_scan_args(argc, argv, "1", &n);
    ary[0] = n;
    ary[1] = rb_ary_new2(NUM2LONG(n));
    rb_block_call(range, idEach, 0, 0, first_i, (VALUE)ary);

    return ary[1];
}


  








  

    #hash  ⇒ Integer   



  

    

Compute a hash-code for this range. Two ranges with equal begin and end points (using #eql?), and the same #exclude_end? value will generate the same hash-code.



See also Object#hash.


  



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# File 'range.c', line 221



static VALUE
range_hash(VALUE range)
{
    st_index_t hash = EXCL(range);
    VALUE v;

    hash = rb_hash_start(hash);
    v = rb_hash(RANGE_BEG(range));
    hash = rb_hash_uint(hash, NUM2LONG(v));
    v = rb_hash(RANGE_END(range));
    hash = rb_hash_uint(hash, NUM2LONG(v));
    hash = rb_hash_uint(hash, EXCL(range) << 24);
    hash = rb_hash_end(hash);

    return ST2FIX(hash);
}


  








  

    

      #member?(obj)  ⇒ Boolean 
      #include?(obj)  ⇒ Boolean 
    

  



  

    

Alias for #member?.


  





  








  

    #initialize_copy(orig)  
  

  

    This method is for internal use only.
  

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# File 'range.c', line 93



static VALUE
range_initialize_copy(VALUE range, VALUE orig)
{
    range_modify(range);
    rb_struct_init_copy(range, orig);
    return range;
}


  








  

    #inspect  ⇒ String   



  

    

Convert this range object to a printable form (using inspect to convert the begin and end objects).


  



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# File 'range.c', line 1100



static VALUE
range_inspect(VALUE range)
{
    return rb_exec_recursive(inspect_range, range, 0);
}


  








  

    

      #last  ⇒ Object 
      #last(n)  ⇒ Array 
    

  



  

    

Returns the last object in the range, or an array of the last n elements.



Note that with no arguments last will return the object that defines the end of the range even if #exclude_end? is true.



(10..20).last      #=> 20
(10...20).last     #=> 20
(10..20).last(3)   #=> [18, 19, 20]
(10...20).last(3)  #=> [17, 18, 19]


  





  


  [ GitHub ]


  

  


# File 'range.c', line 881



static VALUE
range_last(int argc, VALUE *argv, VALUE range)
{
    if (argc == 0) return RANGE_END(range);
    return rb_ary_last(argc, argv, rb_Array(range));
}


  








  

    

      #max  ⇒ Object 
      #max {|a, b| ... } ⇒ Object 
      #max(n)  ⇒ Object 
      #max(n) {|a, b| ... } ⇒ Object 
    

  



  

    

Returns the maximum value in the range. Returns nil if the begin value of the range larger than the end value. Returns nil if the begin value of an exclusive range is equal to the end value.



Can be given an optional block to override the default comparison method a <=> b.



(10..20).max    #=> 20


  





  


  [ GitHub ]


  

  


# File 'range.c', line 945



static VALUE
range_max(int argc, VALUE *argv, VALUE range)
{
    VALUE e = RANGE_END(range);
    int nm = FIXNUM_P(e) || rb_obj_is_kind_of(e, rb_cNumeric);

    if (rb_block_given_p() || (EXCL(range) && !nm) || argc) {
	return rb_call_super(argc, argv);
    }
    else {
	struct cmp_opt_data cmp_opt = { 0, 0 };
	VALUE b = RANGE_BEG(range);
	int c = OPTIMIZED_CMP(b, e, cmp_opt);

	if (c > 0)
	    return Qnil;
	if (EXCL(range)) {
	    if (!FIXNUM_P(e) && !rb_obj_is_kind_of(e, rb_cInteger)) {
		rb_raise(rb_eTypeError, "cannot exclude non Integer end value");
	    }
	    if (c == 0) return Qnil;
	    if (!FIXNUM_P(b) && !rb_obj_is_kind_of(b,rb_cInteger)) {
		rb_raise(rb_eTypeError, "cannot exclude end value with non Integer begin value");
	    }
	    if (FIXNUM_P(e)) {
		return LONG2NUM(FIX2LONG(e) - 1);
	    }
	    return rb_funcall(e, '-', 1, INT2FIX(1));
	}
	return e;
    }
}


  








  

    

      #member?(obj)  ⇒ Boolean 
      #include?(obj)  ⇒ Boolean 
    

    Also known as: #include?
  



  

    

Returns true if obj is an element of the range, false otherwise.  If begin and end are numeric, comparison is done according to the magnitude of the values.



("a".."z").include?("g")   #=> true
("a".."z").include?("A")   #=> false
("a".."z").include?("cc")  #=> false


  





  


  [ GitHub ]


  

  


# File 'range.c', line 1146



static VALUE
range_include(VALUE range, VALUE val)
{
    VALUE beg = RANGE_BEG(range);
    VALUE end = RANGE_END(range);
    int nv = FIXNUM_P(beg) || FIXNUM_P(end) ||
	     linear_object_p(beg) || linear_object_p(end);

    if (nv ||
	!NIL_P(rb_check_to_integer(beg, "to_int")) ||
	!NIL_P(rb_check_to_integer(end, "to_int"))) {
	return r_cover_p(range, beg, end, val);
    }
    else if (RB_TYPE_P(beg, T_STRING) && RB_TYPE_P(end, T_STRING)) {
	VALUE rb_str_include_range_p(VALUE beg, VALUE end, VALUE val, VALUE exclusive);
	return rb_str_include_range_p(beg, end, val, RANGE_EXCL(range));
    }
    /* TODO: ruby_frame->this_func = rb_intern("include?"); */
    return rb_call_super(1, &val);
}


  








  

    

      #min  ⇒ Object 
      #min {|a, b| ... } ⇒ Object 
      #min(n)  ⇒ Array 
      #min(n) {|a, b| ... } ⇒ Array 
    

  



  

    

Returns the minimum value in the range. Returns nil if the begin value of the range is larger than the end value. Returns nil if the begin value of an exclusive range is equal to the end value.



Can be given an optional block to override the default comparison method a <=> b.



(10..20).min    #=> 10


  





  


  [ GitHub ]


  

  


# File 'range.c', line 907



static VALUE
range_min(int argc, VALUE *argv, VALUE range)
{
    if (rb_block_given_p()) {
	return rb_call_super(argc, argv);
    }
    else if (argc != 0) {
	return range_first(argc, argv, range);
    }
    else {
	struct cmp_opt_data cmp_opt = { 0, 0 };
	VALUE b = RANGE_BEG(range);
	VALUE e = RANGE_END(range);
	int c = OPTIMIZED_CMP(b, e, cmp_opt);

	if (c > 0 || (c == 0 && EXCL(range)))
	    return Qnil;
	return b;
    }
}


  








  

    #size  ⇒ Numeric   



  

    

Returns the number of elements in the range. Both the begin and the end of the Range must be ::Numeric, otherwise nil is returned.



(10..20).size    #=> 11
('a'..'z').size  #=> nil
(-Float::INFINITY..Float::INFINITY).size #=> Infinity


  



  [ GitHub ]


  

  


# File 'range.c', line 702



static VALUE
range_size(VALUE range)
{
    VALUE b = RANGE_BEG(range), e = RANGE_END(range);
    if (rb_obj_is_kind_of(b, rb_cNumeric) && rb_obj_is_kind_of(e, rb_cNumeric)) {
	return ruby_num_interval_step_size(b, e, INT2FIX(1), EXCL(range));
    }
    return Qnil;
}


  








  

    

      #step(n = 1) {|obj| ... } ⇒ Range 
      #step(n = 1)  ⇒ Enumerator 
    

  



  

    

Iterates over the range, passing each nth element to the block. If begin and end are numeric, n is added for each iteration. Otherwise step invokes succ to iterate through range elements.



If no block is given, an enumerator is returned instead.



range = Xs.new(1)..Xs.new(10)
range.step(2) {|x| puts x}
puts
range.step(3) {|x| puts x}



produces:



 1 x
 3 xxx
 5 xxxxx
 7 xxxxxxx
 9 xxxxxxxxx

 1 x
 4 xxxx
 7 xxxxxxx
10 xxxxxxxxxx



See Range for the definition of class Xs.


  





  


  [ GitHub ]


  

  


# File 'range.c', line 386



static VALUE
range_step(int argc, VALUE *argv, VALUE range)
{
    VALUE b, e, step, tmp;

    RETURN_SIZED_ENUMERATOR(range, argc, argv, range_step_size);

    b = RANGE_BEG(range);
    e = RANGE_END(range);
    if (argc == 0) {
	step = INT2FIX(1);
    }
    else {
	rb_scan_args(argc, argv, "01", &step);
	step = check_step_domain(step);
    }

    if (FIXNUM_P(b) && FIXNUM_P(e) && FIXNUM_P(step)) { /* fixnums are special */
	long end = FIX2LONG(e);
	long i, unit = FIX2LONG(step);

	if (!EXCL(range))
	    end += 1;
	i = FIX2LONG(b);
	while (i < end) {
	    rb_yield(LONG2NUM(i));
	    if (i + unit < i) break;
	    i += unit;
	}

    }
    else if (SYMBOL_P(b) && SYMBOL_P(e)) { /* symbols are special */
	VALUE args[2], iter[2];

	args[0] = rb_sym2str(e);
	args[1] = EXCL(range) ? Qtrue : Qfalse;
	iter[0] = INT2FIX(1);
	iter[1] = step;
	rb_block_call(rb_sym2str(b), rb_intern("upto"), 2, args, sym_step_i, (VALUE)iter);
    }
    else if (ruby_float_step(b, e, step, EXCL(range))) {
	/* done */
    }
    else if (rb_obj_is_kind_of(b, rb_cNumeric) ||
	     !NIL_P(rb_check_to_integer(b, "to_int")) ||
	     !NIL_P(rb_check_to_integer(e, "to_int"))) {
	ID op = EXCL(range) ? '<' : idLE;
	VALUE v = b;
	int i = 0;

	while (RTEST(rb_funcall(v, op, 1, e))) {
	    rb_yield(v);
	    i++;
	    v = rb_funcall(b, '+', 1, rb_funcall(INT2NUM(i), '*', 1, step));
	}
    }
    else {
	tmp = rb_check_string_type(b);

	if (!NIL_P(tmp)) {
	    VALUE args[2], iter[2];

	    b = tmp;
	    args[0] = e;
	    args[1] = EXCL(range) ? Qtrue : Qfalse;
	    iter[0] = INT2FIX(1);
	    iter[1] = step;
	    rb_block_call(b, rb_intern("upto"), 2, args, step_i, (VALUE)iter);
	}
	else {
	    VALUE args[2];

	    if (!discrete_object_p(b)) {
		rb_raise(rb_eTypeError, "can't iterate from %s",
			 rb_obj_classname(b));
	    }
	    args[0] = INT2FIX(1);
	    args[1] = step;
	    range_each_func(range, step_i, (VALUE)args);
	}
    }
    return range;
}


  








  

    #to_s  ⇒ String   



  

    

Convert this range object to a printable form (using #to_s to convert the begin and end objects).


  



  [ GitHub ]


  

  


# File 'range.c', line 1057



static VALUE
range_to_s(VALUE range)
{
    VALUE str, str2;

    str = rb_obj_as_string(RANGE_BEG(range));
    str2 = rb_obj_as_string(RANGE_END(range));
    str = rb_str_dup(str);
    rb_str_cat(str, "...", EXCL(range) ? 3 : 2);
    rb_str_append(str, str2);
    OBJ_INFECT(str, range);

    return str;
}