Class: Range

Inherits:
Object show all
Includes:
Enumerable
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 Range::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

Instance Method Summary collapse

Methods included from Enumerable

#all?, #any?, #chunk, #collect, #collect_concat, #count, #cycle, #detect, #drop, #drop_while, #each_cons, #each_entry, #each_slice, #each_with_index, #each_with_object, #entries, #find, #find_all, #find_index, #flat_map, #grep, #group_by, #inject, #lazy, #map, #max_by, #min_by, #minmax, #minmax_by, #none?, #one?, #partition, #reduce, #reject, #reverse_each, #select, #slice_before, #sort, #sort_by, #take, #take_while, #to_a, #to_h, #zip

Constructor Details

#newObject

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.



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# File 'range.c', line 103

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 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

Returns:

  • (Boolean)


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# File 'range.c', line 168

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

Returns:

  • (Boolean)


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# File 'range.c', line 1128

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

#beginObject

Returns the object that defines the beginning of the range.

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

Returns:



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# File 'range.c', line 813

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

#bsearch {|obj| ... } ⇒ Object

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 i.

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.

Yields:

  • (obj)


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# File 'range.c', line 577

static VALUE
range_bsearch(VALUE range)
{
    VALUE beg, end;
    int smaller, satisfied = 0;

    /* 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(val) \
    do { \
	VALUE v = rb_yield(val); \
	if (FIXNUM_P(v)) { \
	    if (FIX2INT(v) == 0) return val; \
	    smaller = FIX2INT(v) < 0; \
	} \
	else if (v == Qtrue) { \
	    satisfied = 1; \
	    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 %s" \
		" (must be numeric, true, false or nil)", \
		rb_obj_classname(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; \
	} \
	if (!satisfied) return Qnil; \
	return conv(low); \
    } 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;
	}
	if (!satisfied) return Qnil;
	return low;
    }
    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

Returns:

  • (Boolean)

Returns:

  • (Boolean)


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# File 'range.c', line 1212

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

    beg = RANGE_BEG(range);
    end = RANGE_END(range);
    if (r_le(beg, val)) {
	if (EXCL(range)) {
	    if (r_lt(val, end))
		return Qtrue;
	}
	else {
	    if (r_le(val, end))
		return Qtrue;
	}
    }
    return Qfalse;
}

#each {|i| ... } ⇒ Object #eachObject

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

Overloads:

  • #each {|i| ... } ⇒ Object

    Yields:

    • (i)


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# File 'range.c', line 756

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_sym_to_s(end);
	args[1] = EXCL(range) ? Qtrue : Qfalse;
	rb_block_call(rb_sym_to_s(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;
}

#endObject

Returns the object that defines the end of the range.

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

Returns:



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# File 'range.c', line 831

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

Returns:

  • (Boolean)

Returns:

  • (Boolean)


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# File 'range.c', line 236

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);
}

#exclude_end?Boolean

Returns true if the range excludes its end value.

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

Returns:

  • (Boolean)

Returns:

  • (Boolean)


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# File 'range.c', line 133

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

#firstObject #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]

Overloads:



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# File 'range.c', line 865

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];
}

#hashFixnum

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.

Returns:



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# File 'range.c', line 255

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 LONG2FIX(hash);
}

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

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

Overloads:

  • #member?(obj) ⇒ Boolean

    Returns:

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

    Returns:

    • (Boolean)

Returns:

  • (Boolean)


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# File 'range.c', line 1149

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) ||
	     rb_obj_is_kind_of(beg, rb_cNumeric) ||
	     rb_obj_is_kind_of(end, rb_cNumeric);

    if (nv ||
	!NIL_P(rb_check_to_integer(beg, "to_int")) ||
	!NIL_P(rb_check_to_integer(end, "to_int"))) {
	if (r_le(beg, val)) {
	    if (EXCL(range)) {
		if (r_lt(val, end))
		    return Qtrue;
	    }
	    else {
		if (r_le(val, end))
		    return Qtrue;
	    }
	}
	return Qfalse;
    }
    else if (RB_TYPE_P(beg, T_STRING) && RB_TYPE_P(end, T_STRING) &&
	     RSTRING_LEN(beg) == 1 && RSTRING_LEN(end) == 1) {
	if (NIL_P(val)) return Qfalse;
	if (RB_TYPE_P(val, T_STRING)) {
	    if (RSTRING_LEN(val) == 0 || RSTRING_LEN(val) > 1)
		return Qfalse;
	    else {
		char b = RSTRING_PTR(beg)[0];
		char e = RSTRING_PTR(end)[0];
		char v = RSTRING_PTR(val)[0];

		if (ISASCII(b) && ISASCII(e) && ISASCII(v)) {
		    if (b <= v && v < e) return Qtrue;
		    if (!EXCL(range) && v == e) return Qtrue;
		    return Qfalse;
		}
	    }
	}
    }
    /* TODO: ruby_frame->this_func = rb_intern("include?"); */
    return rb_call_super(1, &val);
}

#initialize_copyObject

:nodoc:



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# File 'range.c', line 115

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

#inspectString

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

Returns:



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# File 'range.c', line 1103

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

#lastObject #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]

Overloads:



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# File 'range.c', line 898

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));
}

#maxObject #max {|a, b| ... } ⇒ Object

Returns the maximum value in the range. Returns nil if the begin value of the range larger than the end value.

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

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

Overloads:



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# File 'range.c', line 952

static VALUE
range_max(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)) {
	return rb_call_super(0, 0);
    }
    else {
	VALUE b = RANGE_BEG(range);
	int c = rb_cmpint(rb_funcall(b, id_cmp, 1, e), b, e);

	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

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

Overloads:

  • #member?(obj) ⇒ Boolean

    Returns:

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

    Returns:

    • (Boolean)

Returns:

  • (Boolean)


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# File 'range.c', line 1149

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) ||
	     rb_obj_is_kind_of(beg, rb_cNumeric) ||
	     rb_obj_is_kind_of(end, rb_cNumeric);

    if (nv ||
	!NIL_P(rb_check_to_integer(beg, "to_int")) ||
	!NIL_P(rb_check_to_integer(end, "to_int"))) {
	if (r_le(beg, val)) {
	    if (EXCL(range)) {
		if (r_lt(val, end))
		    return Qtrue;
	    }
	    else {
		if (r_le(val, end))
		    return Qtrue;
	    }
	}
	return Qfalse;
    }
    else if (RB_TYPE_P(beg, T_STRING) && RB_TYPE_P(end, T_STRING) &&
	     RSTRING_LEN(beg) == 1 && RSTRING_LEN(end) == 1) {
	if (NIL_P(val)) return Qfalse;
	if (RB_TYPE_P(val, T_STRING)) {
	    if (RSTRING_LEN(val) == 0 || RSTRING_LEN(val) > 1)
		return Qfalse;
	    else {
		char b = RSTRING_PTR(beg)[0];
		char e = RSTRING_PTR(end)[0];
		char v = RSTRING_PTR(val)[0];

		if (ISASCII(b) && ISASCII(e) && ISASCII(v)) {
		    if (b <= v && v < e) return Qtrue;
		    if (!EXCL(range) && v == e) return Qtrue;
		    return Qfalse;
		}
	    }
	}
    }
    /* TODO: ruby_frame->this_func = rb_intern("include?"); */
    return rb_call_super(1, &val);
}

#minObject #min {|a, b| ... } ⇒ Object

Returns the minimum value in the range. Returns nil if the begin value of the range is larger than the end value.

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

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

Overloads:



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# File 'range.c', line 921

static VALUE
range_min(VALUE range)
{
    if (rb_block_given_p()) {
	return rb_call_super(0, 0);
    }
    else {
	VALUE b = RANGE_BEG(range);
	VALUE e = RANGE_END(range);
	int c = rb_cmpint(rb_funcall(b, id_cmp, 1, e), b, e);

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

#sizeNumeric

Returns the number of elements in the range.

(10..20).size    #=> 11

Returns:



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# File 'range.c', line 719

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| ... } ⇒ Object #step(n = 1) ⇒ Object

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.

Overloads:

  • #step(n = 1) {|obj| ... } ⇒ Object

    Yields:

    • (obj)


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# File 'range.c', line 397

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);
	if (!rb_obj_is_kind_of(step, rb_cNumeric)) {
	    step = rb_to_int(step);
	}
	if (rb_funcall(step, '<', 1, INT2FIX(0))) {
	    rb_raise(rb_eArgError, "step can't be negative");
	}
	else if (!rb_funcall(step, '>', 1, INT2FIX(0))) {
	    rb_raise(rb_eArgError, "step can't be 0");
	}
    }

    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_sym_to_s(e);
	args[1] = EXCL(range) ? Qtrue : Qfalse;
	iter[0] = INT2FIX(1);
	iter[1] = step;
	rb_block_call(rb_sym_to_s(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_sString

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

Returns:



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# File 'range.c', line 1060

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, str2);

    return str;
}