A Range represents an interval—a set of values with a start 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 start 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"]
Ranges can be constructed using objects of any type, as long as the objects can be compared using their <=> operator and they support the succ method to return the next object in sequence.
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 r = Xs.new(3)..Xs.new(6) #=> xxx..xxxxxx r.to_a #=> [xxx, xxxx, xxxxx, xxxxxx] r.member?(Xs.new(5)) #=> true
In the previous code example, class Xs includes the Comparable module. This is because Enumerable#member? checks for equality using ==. Including Comparable ensures that the == method is defined in terms of the <=> method implemented in Xs.
Constructs a range using the given start and end. If the third parameter is omitted or is false, the range will include the end object; otherwise, it will be excluded.
/* * call-seq: * Range.new(start, end, exclusive=false) => range * * Constructs a range using the given <i>start</i> and <i>end</i>. If the third * parameter is omitted or is <code>false</code>, the <i>range</i> will include * the end object; otherwise, it will be excluded. */ static VALUE range_initialize(argc, argv, range) int argc; VALUE *argv; VALUE range; { VALUE beg, end, flags; rb_scan_args(argc, argv, "21", &beg, &end, &flags); /* Ranges are immutable, so that they should be initialized only once. */ if (rb_ivar_defined(range, id_beg)) { rb_name_error(rb_intern("initialize"), "`initialize' called twice"); } range_init(range, beg, end, RTEST(flags)); return Qnil; }
Returns true only if obj is a Range, has equivalent beginning and end items (by comparing them with ==), and has the same exclude_end? setting as <i>rng</t>.
(0..2) == (0..2) #=> true (0..2) == Range.new(0,2) #=> true (0..2) == (0...2) #=> false
/* * call-seq: * rng == obj => true or false * * Returns <code>true</code> only if <i>obj</i> is a Range, has equivalent * beginning and end items (by comparing them with <code>==</code>), and has * the same #exclude_end? setting as <i>rng</t>. * * (0..2) == (0..2) #=> true * (0..2) == Range.new(0,2) #=> true * (0..2) == (0...2) #=> false * */ static VALUE range_eq(range, obj) VALUE range, obj; { if (range == obj) return Qtrue; if (!rb_obj_is_instance_of(obj, rb_obj_class(range))) return Qfalse; if (!rb_equal(rb_ivar_get(range, id_beg), rb_ivar_get(obj, id_beg))) return Qfalse; if (!rb_equal(rb_ivar_get(range, id_end), rb_ivar_get(obj, id_end))) return Qfalse; if (EXCL(range) != EXCL(obj)) return Qfalse; return Qtrue; }
Returns true if obj is an element of rng, 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
/* * call-seq: * rng === obj => true or false * rng.member?(val) => true or false * rng.include?(val) => true or false * * Returns <code>true</code> if <i>obj</i> is an element of * <i>rng</i>, <code>false</code> otherwise. Conveniently, * <code>===</code> is the comparison operator used by * <code>case</code> 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 * * <em>produces:</em> * * high */ static VALUE range_include(range, val) VALUE range, val; { VALUE beg, end; beg = rb_ivar_get(range, id_beg); end = rb_ivar_get(range, id_end); 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; }
Iterates over the elements rng, passing each in turn to the block. You can only iterate if the start object of the range supports the succ method (which means that you can‘t iterate over ranges of Float objects).
(10..15).each do |n| print n, ' ' end
produces:
10 11 12 13 14 15
/* * call-seq: * rng.each {| i | block } => rng * * Iterates over the elements <i>rng</i>, passing each in turn to the * block. You can only iterate if the start object of the range * supports the +succ+ method (which means that you can't iterate over * ranges of +Float+ objects). * * (10..15).each do |n| * print n, ' ' * end * * <em>produces:</em> * * 10 11 12 13 14 15 */ static VALUE range_each(range) VALUE range; { VALUE beg, end; RETURN_ENUMERATOR(range, 0, 0); beg = rb_ivar_get(range, id_beg); end = rb_ivar_get(range, id_end); if (!rb_respond_to(beg, id_succ)) { rb_raise(rb_eTypeError, "can't iterate from %s", rb_obj_classname(beg)); } 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(LONG2NUM(i)); } } else if (TYPE(beg) == T_STRING) { VALUE args[5], iter[2]; args[0] = beg; args[1] = end; args[2] = range; iter[0] = INT2FIX(1); iter[1] = INT2FIX(1); rb_iterate((VALUE(*)_((VALUE)))str_step, (VALUE)args, step_i, (VALUE)iter); } else { range_each_func(range, each_i, beg, end, NULL); } return range; }
Returns the object that defines the end of rng.
(1..10).end #=> 10 (1...10).end #=> 10
/* * call-seq: * rng.end => obj * rng.last => obj * * Returns the object that defines the end of <i>rng</i>. * * (1..10).end #=> 10 * (1...10).end #=> 10 */ static VALUE range_last(range) VALUE range; { return rb_ivar_get(range, id_end); }
Returns true only if obj is a Range, has equivalent beginning and end items (by comparing them with eql?), and has the same exclude_end? setting as rng.
(0..2) == (0..2) #=> true (0..2) == Range.new(0,2) #=> true (0..2) == (0...2) #=> false
/* * call-seq: * rng.eql?(obj) => true or false * * Returns <code>true</code> only if <i>obj</i> is a Range, has equivalent * beginning and end items (by comparing them with #eql?), and has the same * #exclude_end? setting as <i>rng</i>. * * (0..2) == (0..2) #=> true * (0..2) == Range.new(0,2) #=> true * (0..2) == (0...2) #=> false * */ static VALUE range_eql(range, obj) VALUE range, obj; { if (range == obj) return Qtrue; if (!rb_obj_is_instance_of(obj, rb_obj_class(range))) return Qfalse; if (!rb_eql(rb_ivar_get(range, id_beg), rb_ivar_get(obj, id_beg))) return Qfalse; if (!rb_eql(rb_ivar_get(range, id_end), rb_ivar_get(obj, id_end))) return Qfalse; if (EXCL(range) != EXCL(obj)) return Qfalse; return Qtrue; }
Generate a hash value such that two ranges with the same start and end points, and the same value for the "exclude end" flag, generate the same hash value.
/* * call-seq: * rng.hash => fixnum * * Generate a hash value such that two ranges with the same start and * end points, and the same value for the "exclude end" flag, generate * the same hash value. */ static VALUE range_hash(range) VALUE range; { long hash = EXCL(range); VALUE v; v = rb_hash(rb_ivar_get(range, id_beg)); hash ^= v << 1; v = rb_hash(rb_ivar_get(range, id_end)); hash ^= v << 9; hash ^= EXCL(range) << 24; return LONG2FIX(hash); }
Returns true if obj is an element of rng, 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
/* * call-seq: * rng === obj => true or false * rng.member?(val) => true or false * rng.include?(val) => true or false * * Returns <code>true</code> if <i>obj</i> is an element of * <i>rng</i>, <code>false</code> otherwise. Conveniently, * <code>===</code> is the comparison operator used by * <code>case</code> 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 * * <em>produces:</em> * * high */ static VALUE range_include(range, val) VALUE range, val; { VALUE beg, end; beg = rb_ivar_get(range, id_beg); end = rb_ivar_get(range, id_end); 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; }
Convert this range object to a printable form (using inspect to convert the start and end objects).
/* * call-seq: * rng.inspect => string * * Convert this range object to a printable form (using * <code>inspect</code> to convert the start and end * objects). */ static VALUE range_inspect(range) VALUE range; { VALUE str, str2; str = rb_inspect(rb_ivar_get(range, id_beg)); str2 = rb_inspect(rb_ivar_get(range, id_end)); str = rb_str_dup(str); rb_str_cat(str, "...", EXCL(range)?3:2); rb_str_append(str, str2); OBJ_INFECT(str, str2); return str; }
Returns the object that defines the end of rng.
(1..10).end #=> 10 (1...10).end #=> 10
/* * call-seq: * rng.end => obj * rng.last => obj * * Returns the object that defines the end of <i>rng</i>. * * (1..10).end #=> 10 * (1...10).end #=> 10 */ static VALUE range_last(range) VALUE range; { return rb_ivar_get(range, id_end); }
Returns true if obj is an element of rng, 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
/* * call-seq: * rng === obj => true or false * rng.member?(val) => true or false * rng.include?(val) => true or false * * Returns <code>true</code> if <i>obj</i> is an element of * <i>rng</i>, <code>false</code> otherwise. Conveniently, * <code>===</code> is the comparison operator used by * <code>case</code> 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 * * <em>produces:</em> * * high */ static VALUE range_include(range, val) VALUE range, val; { VALUE beg, end; beg = rb_ivar_get(range, id_beg); end = rb_ivar_get(range, id_end); 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; }
Iterates over rng, passing each nth element to the block. If the range contains numbers, n is added for each iteration. Otherwise step invokes succ to iterate through range elements. The following code uses class Xs, which is defined in the class-level documentation.
range = Xs.new(1)..Xs.new(10) range.step(2) {|x| puts x} 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
/* * call-seq: * rng.step(n=1) {| obj | block } => rng * * Iterates over <i>rng</i>, passing each <i>n</i>th element to the block. If * the range contains numbers, <i>n</i> is added for each iteration. Otherwise * <code>step</code> invokes <code>succ</code> to iterate through range * elements. The following code uses class <code>Xs</code>, which is defined * in the class-level documentation. * * range = Xs.new(1)..Xs.new(10) * range.step(2) {|x| puts x} * range.step(3) {|x| puts x} * * <em>produces:</em> * * 1 x * 3 xxx * 5 xxxxx * 7 xxxxxxx * 9 xxxxxxxxx * 1 x * 4 xxxx * 7 xxxxxxx * 10 xxxxxxxxxx */ static VALUE range_step(argc, argv, range) int argc; VALUE *argv; VALUE range; { VALUE b, e, step, tmp; RETURN_ENUMERATOR(range, argc, argv); b = rb_ivar_get(range, id_beg); e = rb_ivar_get(range, id_end); 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 (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) ? '<' : rb_intern("<="); while (RTEST(rb_funcall(b, op, 1, e))) { rb_yield(b); b = rb_funcall(b, '+', 1, step); } } else { tmp = rb_check_string_type(b); if (!NIL_P(tmp)) { VALUE args[5], 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 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 c = EXCL(range) ? '<' : rb_intern("<="); while (RTEST(rb_funcall(b, c, 1, e))) { rb_yield(b); b = rb_funcall(b, '+', 1, step); } } else { VALUE args[2]; if (!rb_respond_to(b, id_succ)) { 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, b, e, args); } } return range; }
Convert this range object to a printable form.
/* * call-seq: * rng.to_s => string * * Convert this range object to a printable form. */ static VALUE range_to_s(range) VALUE range; { VALUE str, str2; str = rb_obj_as_string(rb_ivar_get(range, id_beg)); str2 = rb_obj_as_string(rb_ivar_get(range, id_end)); str = rb_str_dup(str); rb_str_cat(str, "...", EXCL(range)?3:2); rb_str_append(str, str2); OBJ_INFECT(str, str2); return str; }