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Class: Enumerator::ArithmeticSequence

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

Overview

ArithmeticSequence is a subclass of ::Enumerator, that is a representation of sequences of numbers with common difference. Instances of this class can be generated by the Range#step and Numeric#step methods.

The class can be used for slicing ::Array (see Array#slice) or custom collections.

Class Method Summary

::Enumerator - Inherited

.new

Creates a new ::Enumerator object, which can be used as an ::Enumerable.
.produce

Creates an infinite enumerator from any block, just called over and over.
.product

Generates a new enumerator object that generates a Cartesian product of given enumerable objects.

Instance Attribute Summary

Instance Method Summary

::Enumerator - Inherited

#+

Returns an enumerator object generated from this enumerator and a given enumerable.
#each

Iterates over the block according to how this ::Enumerator was constructed.
#each_with_index

Same as #with_index(0), i.e. there is no starting offset.
#each_with_object

Alias for #with_object.
#feed

Sets the value to be returned by the next yield inside e.
#inspect

Creates a printable version of e.
#next

Returns the next object in the enumerator, and move the internal position forward.
#next_values

Returns the next object as an array in the enumerator, and move the internal position forward.
#peek

Returns the next object in the enumerator, but doesn’t move the internal position forward.
#peek_values

Returns the next object as an array, similar to #next_values, but doesn’t move the internal position forward.
#rewind

Rewinds the enumeration sequence to the beginning.
#size

Returns the size of the enumerator, or nil if it can’t be calculated lazily.
#with_index

Iterates the given block for each element with an index, which starts from offset.
#with_object

Iterates the given block for each element with an arbitrary object, obj, and returns obj
#initialize_copy

::Enumerable - Included

#all?

Returns whether every element meets a given criterion.
#any?

Returns whether any element meets a given criterion.
#chain

Returns an enumerator object generated from this enumerator and given enumerables.
#chunk

Each element in the returned enumerator is a 2-element array consisting of:
#chunk_while

Creates an enumerator for each chunked elements.
#collect

Alias for Enumerable#map.
#collect_concat

Alias for Enumerable#flat_map.
#compact

Returns an array of all non-nil elements:
#count

Returns the count of elements, based on an argument or block criterion, if given.
#cycle

When called with positive integer argument n and a block, calls the block with each element, then does so again, until it has done so n times; returns nil:
#detect

Alias for Enumerable#find.
#drop

For positive integer n, returns an array containing all but the first n elements:
#drop_while

Calls the block with successive elements as long as the block returns a truthy value; returns an array of all elements after that point:
#each_cons

Calls the block with each successive overlapped n-tuple of elements; returns self:
#each_entry

Calls the given block with each element, converting multiple values from yield to an array; returns self:
#each_slice

Calls the block with each successive disjoint n-tuple of elements; returns self:
#each_with_index

Invoke self.each with *args.
#each_with_object

Calls the block once for each element, passing both the element and the given object:
#entries

Alias for Enumerable#to_a.
#filter

Returns an array containing elements selected by the block.
#filter_map

Returns an array containing truthy elements returned by the block.
#find

Returns the first element for which the block returns a truthy value.
#find_all

Alias for Enumerable#filter.
#find_index

Returns the index of the first element that meets a specified criterion, or nil if no such element is found.
#first

Returns the first element or elements.
#flat_map

Returns an array of flattened objects returned by the block.
#grep

Returns an array of objects based elements of self that match the given pattern.
#grep_v

Returns an array of objects based on elements of self that don’t match the given pattern.
#group_by

With a block given returns a hash:
#include?

Alias for Enumerable#member?.
#inject

Returns the result of applying a reducer to an initial value and the first element of the ::Enumerable.
#lazy

Returns an Lazy, which redefines most ::Enumerable methods to postpone enumeration and enumerate values only on an as-needed basis.
#map

Returns an array of objects returned by the block.
#max

Returns the element with the maximum element according to a given criterion.
#max_by

Returns the elements for which the block returns the maximum values.
#member?

Returns whether for any element object == element:
#min

Returns the element with the minimum element according to a given criterion.
#min_by

Returns the elements for which the block returns the minimum values.
#minmax

Returns a 2-element array containing the minimum and maximum elements according to a given criterion.
#minmax_by

Returns a 2-element array containing the elements for which the block returns minimum and maximum values:
#none?

Returns whether no element meets a given criterion.
#one?

Returns whether exactly one element meets a given criterion.
#partition

With a block given, returns an array of two arrays:
#reduce

Alias for Enumerable#inject.
#reject

Returns an array of objects rejected by the block.
#reverse_each

With a block given, calls the block with each element, but in reverse order; returns self:
#select

Alias for Enumerable#filter.
#slice_after

Creates an enumerator for each chunked elements.
#slice_before

With argument pattern, returns an enumerator that uses the pattern to partition elements into arrays (“slices”).
#slice_when

Creates an enumerator for each chunked elements.
#sort

Returns an array containing the sorted elements of self.
#sort_by

With a block given, returns an array of elements of self, sorted according to the value returned by the block for each element.
#sum

With no block given, returns the sum of initial_value and the elements:
#take

For non-negative integer n, returns the first n elements:
#take_while

Calls the block with successive elements as long as the block returns a truthy value; returns an array of all elements up to that point:
#tally

When argument #hash is not given, returns a new hash whose keys are the distinct elements in self; each integer value is the count of occurrences of each element:
#to_a

Returns an array containing the items in self:
#to_h

When self consists of 2-element arrays, returns a hash each of whose entries is the key-value pair formed from one of those arrays:
#to_set

Makes a set from the enumerable object with given arguments.
#uniq

With no block, returns a new array containing only unique elements; the array has no two elements e0 and e1 such that e0.eql?(e1):
#zip

With no block given, returns a new array new_array of size self.size whose elements are arrays.

Constructor Details

This class inherits a constructor from Enumerator

Instance Attribute Details

#exclude_end? ⇒ Boolean (readonly)

[ GitHub ]

Instance Method Details

#==(obj) ⇒ Boolean Also known as: #===, #eql?

Returns true only if obj is an ArithmeticSequence, has equivalent begin, end, step, and exclude_end? settings.

[ GitHub ] 

  


# File 'enumerator.c', line 4260



static VALUE
arith_seq_eq(VALUE self, VALUE other)
{
    if (!RTEST(rb_obj_is_kind_of(other, rb_cArithSeq))) {
        return Qfalse;
    }

    if (!rb_equal(arith_seq_begin(self), arith_seq_begin(other))) {
        return Qfalse;
    }

    if (!rb_equal(arith_seq_end(self), arith_seq_end(other))) {
        return Qfalse;
    }

    if (!rb_equal(arith_seq_step(self), arith_seq_step(other))) {
        return Qfalse;
    }

    if (arith_seq_exclude_end_p(self) != arith_seq_exclude_end_p(other)) {
        return Qfalse;
    }

    return Qtrue;
}


  








  

    

      #==(obj)  ⇒ Boolean 
      #===(obj)  ⇒ Boolean 
    

  



  

    

Alias for #==.


  





  








  

    #begin  
  

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    #end  
  

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      #==(obj)  ⇒ Boolean 
      #eql?(obj)  ⇒ Boolean 
    

  



  

    

Alias for #==.


  





  








  

    

      #first  ⇒ Numeric? 
      #first(n)  ⇒ Array 
    

  



  

    

Returns the first number in this arithmetic sequence, or an array of the first n elements.


  





  


  [ GitHub ]


  

  


# File 'enumerator.c', line 3901



static VALUE
arith_seq_first(int argc, VALUE *argv, VALUE self)
{
    VALUE b, e, s, ary;
    long n;
    int x;

    rb_check_arity(argc, 0, 1);

    b = arith_seq_begin(self);
    e = arith_seq_end(self);
    s = arith_seq_step(self);
    if (argc == 0) {
        if (NIL_P(b)) {
            return Qnil;
        }
        if (!NIL_P(e)) {
            VALUE zero = INT2FIX(0);
            int r = rb_cmpint(rb_num_coerce_cmp(s, zero, idCmp), s, zero);
            if (r > 0 && RTEST(rb_funcall(b, '>', 1, e))) {
                return Qnil;
            }
            if (r < 0 && RTEST(rb_funcall(b, '<', 1, e))) {
                return Qnil;
            }
        }
        return b;
    }

    // TODO: the following code should be extracted as arith_seq_take

    n = NUM2LONG(argv[0]);
    if (n < 0) {
        rb_raise(rb_eArgError, "attempt to take negative size");
    }
    if (n == 0) {
        return rb_ary_new_capa(0);
    }

    x = arith_seq_exclude_end_p(self);

    if (FIXNUM_P(b) && NIL_P(e) && FIXNUM_P(s)) {
        long i = FIX2LONG(b), unit = FIX2LONG(s);
        ary = rb_ary_new_capa(n);
        while (n > 0 && FIXABLE(i)) {
            rb_ary_push(ary, LONG2FIX(i));
            i += unit;  // FIXABLE + FIXABLE never overflow;
            --n;
        }
        if (n > 0) {
            b = LONG2NUM(i);
            while (n > 0) {
                rb_ary_push(ary, b);
                b = rb_big_plus(b, s);
                --n;
            }
        }
        return ary;
    }
    else if (FIXNUM_P(b) && FIXNUM_P(e) && FIXNUM_P(s)) {
        long i = FIX2LONG(b);
        long end = FIX2LONG(e);
        long unit = FIX2LONG(s);
        long len;

        if (unit >= 0) {
            if (!x) end += 1;

            len = end - i;
            if (len < 0) len = 0;
            ary = rb_ary_new_capa((n < len) ? n : len);
            while (n > 0 && i < end) {
                rb_ary_push(ary, LONG2FIX(i));
                if (i + unit < i) break;
                i += unit;
                --n;
            }
        }
        else {
            if (!x) end -= 1;

            len = i - end;
            if (len < 0) len = 0;
            ary = rb_ary_new_capa((n < len) ? n : len);
            while (n > 0 && i > end) {
                rb_ary_push(ary, LONG2FIX(i));
                if (i + unit > i) break;
                i += unit;
                --n;
            }
        }
        return ary;
    }
    else if (RB_FLOAT_TYPE_P(b) || RB_FLOAT_TYPE_P(e) || RB_FLOAT_TYPE_P(s)) {
        /* generate values like ruby_float_step */

        double unit = NUM2DBL(s);
        double beg = NUM2DBL(b);
        double end = NIL_P(e) ? (unit < 0 ? -1 : 1)*HUGE_VAL : NUM2DBL(e);
        double len = ruby_float_step_size(beg, end, unit, x);
        long i;

        if (n > len)
            n = (long)len;

        if (isinf(unit)) {
            if (len > 0) {
                ary = rb_ary_new_capa(1);
                rb_ary_push(ary, DBL2NUM(beg));
            }
            else {
                ary = rb_ary_new_capa(0);
            }
        }
        else if (unit == 0) {
            VALUE val = DBL2NUM(beg);
            ary = rb_ary_new_capa(n);
            for (i = 0; i < len; ++i) {
                rb_ary_push(ary, val);
            }
        }
        else {
            ary = rb_ary_new_capa(n);
            for (i = 0; i < n; ++i) {
                double d = i*unit+beg;
                if (unit >= 0 ? end < d : d < end) d = end;
                rb_ary_push(ary, DBL2NUM(d));
            }
        }

        return ary;
    }

    return rb_call_super(argc, argv);
}


  








  

    #hash  ⇒ Integer   



  

    

Compute a hash-value for this arithmetic sequence. Two arithmetic sequences with same begin, end, step, and exclude_end? values will generate the same hash-value.



See also Object#hash.


  



  [ GitHub ]


  

  


# File 'enumerator.c', line 4296



static VALUE
arith_seq_hash(VALUE self)
{
    st_index_t hash;
    VALUE v;

    hash = rb_hash_start(arith_seq_exclude_end_p(self));
    v = rb_hash(arith_seq_begin(self));
    hash = rb_hash_uint(hash, NUM2LONG(v));
    v = rb_hash(arith_seq_end(self));
    hash = rb_hash_uint(hash, NUM2LONG(v));
    v = rb_hash(arith_seq_step(self));
    hash = rb_hash_uint(hash, NUM2LONG(v));
    hash = rb_hash_end(hash);

    return ST2FIX(hash);
}


  








  

    

      #last  ⇒ Numeric? 
      #last(n)  ⇒ Array 
    

  



  

    

Returns the last number in this arithmetic sequence, or an array of the last n elements.


  





  


  [ GitHub ]


  

  


# File 'enumerator.c', line 4127



static VALUE
arith_seq_last(int argc, VALUE *argv, VALUE self)
{
    VALUE b, e, s, len_1, len, last, nv, ary;
    int last_is_adjusted;
    long n;

    e = arith_seq_end(self);
    if (NIL_P(e)) {
        rb_raise(rb_eRangeError,
                 "cannot get the last element of endless arithmetic sequence");
    }

    b = arith_seq_begin(self);
    s = arith_seq_step(self);

    len_1 = num_idiv(num_minus(e, b), s);
    if (rb_num_negative_int_p(len_1)) {
        if (argc == 0) {
            return Qnil;
        }
        return rb_ary_new_capa(0);
    }

    last = num_plus(b, num_mul(s, len_1));
    if ((last_is_adjusted = arith_seq_exclude_end_p(self) && rb_equal(last, e))) {
        last = num_minus(last, s);
    }

    if (argc == 0) {
        return last;
    }

    if (last_is_adjusted) {
        len = len_1;
    }
    else {
        len = rb_int_plus(len_1, INT2FIX(1));
    }

    rb_scan_args(argc, argv, "1", &nv);
    if (!RB_INTEGER_TYPE_P(nv)) {
        nv = rb_to_int(nv);
    }
    if (RTEST(rb_int_gt(nv, len))) {
        nv = len;
    }
    n = NUM2LONG(nv);
    if (n < 0) {
        rb_raise(rb_eArgError, "negative array size");
    }

    ary = rb_ary_new_capa(n);
    b = rb_int_minus(last, rb_int_mul(s, nv));
    while (n) {
        b = rb_int_plus(b, s);
        rb_ary_push(ary, b);
        --n;
    }

    return ary;
}


  








  

    #step  
  

  [ GitHub ]