std.range
This module defines a few useful range incarnations. Credit for some of the ideas in building this module goes to Leonardo Maffi. Source:std/range.d License:
Boost License 1.0. Authors:
Andrei Alexandrescu, David Simcha
- Returns true if R is an input range. An input range must
define the primitives empty, popFront, and front. The
following code should compile for any input range.
R r; // can define a range object if (r.empty) {} // can test for empty r.popFront; // can invoke next auto h = r.front; // can get the front of the range
The semantics of an input range (not checkable during compilation) are assumed to be the following (r is an object of type R):- r.empty returns false iff there is more data available in the range.
- r.front returns the current element in the range. It may return by value or by reference. Calling r.front is allowed only if calling r.empty has, or would have, returned false.
- r.popFront advances to the popFront element in the range. Calling r.popFront is allowed only if calling r.empty has, or would have, returned false.
- Outputs e to r. The exact effect is dependent upon the two types. which must be an output range. Several cases are accepted, as described below. The code snippets are attempted in order, and the first to compile "wins" and gets evaluated.
- Returns true if R is an output range for elements of type E. An output range can be defined functionally as a range that supports the operation put(r, e) as defined above.
- Returns true if R is a forward range. A forward range is an
input range that can save "checkpoints" by simply copying it to
another value of the same type. Notable examples of input ranges that
are not forward ranges are file/socket ranges; copying such a
range will not save the position in the stream, and they most likely
reuse an internal buffer as the entire stream does not sit in
memory. Subsequently, advancing either the original or the copy will
advance the stream, so the copies are not independent. The following
code should compile for any forward range.
static assert(isInputRange!(R)); R r1; R r2 = r1; // can copy a range to another
The semantics of a forward range (not checkable during compilation) are the same as for an input range, with the additional requirement that backtracking must be possible by saving a copy of the range object. - Returns true if R is a bidirectional range. A bidirectional
range is a forward range that also offers the primitives back and
popBack. The following code should compile for any bidirectional
range.
R r; static assert(isForwardRange!(R)); // range is an input range r.popBack; // can invoke popBack auto t = r.back; // can get the back of the range
The semantics of a bidirectional range (not checkable during compilation) are assumed to be the following (r is an object of type R):- r.back returns (possibly a reference to) the last element in the range. Calling r.back is allowed only if calling r.empty has, or would have, returned false.
- Returns true if R is a random-access range. A random-access
range is a bidirectional range that also offers the primitive opIndex, OR an infinite forward range that offers opIndex. In
either case, the range must either offer length or be
infinite. The following code should compile for any random-access
range.
R r; static assert(isForwardRange!(R)); // range is forward static assert(isBidirectionalRange!(R) || isInfinite!(R)); // range is bidirectional or infinite auto e = r[1]; // can index
The semantics of a random-access range (not checkable during compilation) are assumed to be the following (r is an object of type R):- r.opIndex(n) returns a reference to the nth element in the range.
- Returns true iff the range supports the moveFront primitive, as well as moveBack and moveAt if it's a bidirectional or random access range. These may be explicitly implemented, or may work via the default behavior of the module level functions moveFront and friends.
- The element type of R. R does not have to be a range. The element type is determined as the type yielded by r.front for an object r or type R. For example, ElementType!(T[]) is T.
- Returns true if R is a forward range and has swappable
elements. The following code should compile for any random-access
range.
R r; static assert(isForwardRange!(R)); // range is forward swap(r.front, r.front); // can swap elements of the range
- Returns true if R is a forward range and has mutable
elements. The following code should compile for any random-access
range.
R r; static assert(isForwardRange!(R)); // range is forward auto e = r.front; r.front = e; // can assign elements of the range
- Tests whether R has lvalue elements. These are defined as elements that can be passed by reference and have their address taken.
- Returns true if R has a length member that returns an integral type. R does not have to be a range. Note that length is an optional primitive as no range must implement it. Some ranges do not store their length explicitly, some cannot compute it without actually exhausting the range (e.g. socket streams), and some other ranges may be infinite.
- Returns true if Range is an infinite input range. An
infinite input range is an input range that has a statically-defined
enumerated member called empty that is always false, for
example:
struct InfiniteRange { enum bool empty = false; ... }
- Returns true if Range offers a slicing operator with
integral boundaries, that in turn returns an input range type. The
following code should compile for hasSlicing to be true:
Range r; auto s = r[1 .. 2]; static assert(isInputRange!(typeof(s)));
- This is a best-effort implementation of length for any kind of range. If hasLength!(Range), simply returns range.length without checking upTo. Otherwise, walks the range through its length and returns the number of elements seen. Performes Ο(n) evaluations of range.empty and range.popFront, where n is the effective length of range. The upTo parameter is useful to "cut the losses" in case the interest is in seeing whether the range has at least some number of elements. If the parameter upTo is specified, stops if upTo steps have been taken and returns upTo.
- Iterates a bidirectional range backwards.
Example:
int[] a = [ 1, 2, 3, 4, 5 ]; assert(equal(retro(a), [ 5, 4, 3, 2, 1 ][]));
- Forwards to input.empty.
- Returns a copy of this.
- Forwards to input.popBack.
- Forwards to moveBack(input)
- Forwards to input.popFront.
- Forwards to moveFront(input).
- Support for assignment.
- Support for assignment.
- Forwards to input[input.length - n + 1]. Defined only if R is a random access range and if R defines R.length.
- Forwards to input[input.length - n + 1]. Defined only if R is a random access range and if R defines R.length.
- Forwards to input[input.length - n + 1]. Defined only if R is a random access range and if R defines R.length.
- Forwards to input[input.length - n + 1]. Defined only if R is a random access range and if R defines R.length.
- Range primitive operation that returns the length of the range. Forwards to input.length and is defined only if hasLength!(R).
- Iterates range r with stride n. If the range is a
random-access range, moves by indexing into the range; otehrwise,
moves by successive calls to popFront.
Example:
int[] a = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 ]; assert(equal(stride(a, 3), [ 1, 4, 7, 10 ][]));
- this(R input, size_t n);
- Initializes the stride.
- Returns this.
- Forwards to input.empty.
- Forwards to moveFront(input).
- @@@
- Forwards to input.popBack.
- Forwards to input.back after getting rid of any slack items.
- Forwards to moveBack(input). Forwards to input.back after getting rid of any slack items.
- Forwards to input.back after getting rid of any slack items.
- Forwards to input[input.length - n + 1]. Defined only if R is a random access range and if R defines R.length.
- Forwards to moveAt(input, n). Forwards to input[input.length - n + 1]. Defined only if R is a random access range and if R defines R.length.
- Forwards to input[input.length - n + 1]. Defined only if R is a random access range and if R defines R.length.
- Support slicing of the Stride, if the underlying range supports this.
- Range primitive operation that returns the length of the range. Forwards to input.length and is defined only if hasLength!(R).
- Spans multiple ranges in sequence. The function chain takes any
number of ranges and returns a Chain!(R1, R2,...) object. The
ranges may be different, but they must have the same element type. The
result is a range that offers the front, popFront, and empty
primitives. If all input ranges offer random access and length,
Chain offers them as well.
If only one range is offered to Chain or chain, the Chain
type exits the picture by aliasing itself directly to that range's
type.
Example:
int[] arr1 = [ 1, 2, 3, 4 ]; int[] arr2 = [ 5, 6 ]; int[] arr3 = [ 7 ]; auto s = chain(arr1, arr2, arr3); assert(s.length == 7); assert(s[5] == 6); assert(equal(s, [1, 2, 3, 4, 5, 6, 7][]));
- Iterates a random-access range starting from a given point and
progressively extending left and right from that point. If no initial
point is given, iteration starts from the middle of the
range. Iteration spans the entire range.
Example:
int[] a = [ 1, 2, 3, 4, 5 ]; assert(equal(radial(a), [ 3, 4, 2, 5, 1 ][])); a = [ 1, 2, 3, 4 ]; assert(equal(radial(a), [ 2, 3, 1, 4 ][]));
- this(R input);
- Takes a range and starts iterating from its median point. Ranges with an even length start iterating from the element to the left of the median. The second iterated element, if any, is the one to the right of the first iterated element. A convenient way to use this constructor is by calling the helper function radial(input).
- this(R input, size_t startingPoint);
- Takes a range and starts iterating from input[mid]. The second iterated element, if any, is the one to the right of the first iterated element. If there is no element to the right of input[mid], iteration continues downwards with input[mid - 1] etc. A convenient way to use this constructor is by calling the helper function radial(input, startingPoint).
- Returns this.
- Range primitive operation that returns true iff there are no more elements to be iterated.
- Range primitive operation that advances the range to its next element.
- Lazily takes only up to n elements of a range. This is
particulary useful when using with infinite ranges. If the range
offers random access and length, Take offers them as well.
Example:
int[] arr1 = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]; auto s = take(arr1, 5); assert(s.length == 5); assert(s[4] == 5); assert(equal(s, [ 1, 2, 3, 4, 5 ][]));
- Eagerly advances r itself (not a copy) n times (by calling
r.popFront n times). The pass of r into popFrontN
is by reference, so the original range is affected. Completes in
Ο(1) steps for ranges that support slicing, and in Ο(n)
time for all other ranges.
Example:
int[] a = [ 1, 2, 3, 4, 5 ]; a.popFrontN(2); assert(a == [ 3, 4, 5 ]);
- Eagerly reduces r itself (not a copy) n times from its right
side (by calling r.popBack n times). The pass of r into
popBackN is by reference, so the original range is
affected. Completes in Ο(1) steps for ranges that support
slicing, and in Ο(n) time for all other ranges.
Example:
int[] a = [ 1, 2, 3, 4, 5 ]; a.popBackN(2); assert(a == [ 1, 2, 3 ]);
- Repeats one value forever. Example:
enforce(equal(take(repeat(5), 4), [ 5, 5, 5, 5 ][]));
- Range primitive implementations.
- Replicates value exactly n times. Equivalent to take(repeat(value), n).
- struct Cycle(Range) if (isForwardRange!(Unqual!(Range)) && !isInfinite!(Unqual!(Range)));
template Cycle(R) if (isInfinite!(R))
struct Cycle(R) if (isStaticArray!(R));
Cycle!(R) cycle(R)(R input);
Cycle!(R) cycle(R)(R input, size_t index);
Cycle!(R) cycle(R)(R input);
Cycle!(R) cycle(R)(ref R input, size_t index = 0); - Repeats the given forward range ad infinitum. If the original range is
infinite (fact that would make Cycle the identity application),
Cycle detects that and aliases itself to the range type
itself. If the original range has random access, Cycle offers
random access and also offers a constructor taking an initial position
index. Cycle is specialized for statically-sized arrays,
mostly for performance reasons.
Example:
assert(equal(take(cycle([1, 2][]), 5), [ 1, 2, 1, 2, 1 ][]));
Tip:
This is a great way to implement simple circular buffers.- Ditto
- Iterate several ranges in lockstep. The element type is a proxy tuple
that allows accessing the current element in the nth range by
using e[n].
Example:
int[] a = [ 1, 2, 3 ]; string[] b = [ "a", "b", "c" ]; // prints 1:a 2:b 3:c foreach (e; zip(a, b)) { write(e[0], ':', e[1], ' '); }
Zip offers the lowest range facilities of all components, e.g. it offers random access iff all ranges offer random access, and also offers mutation and swapping if all ranges offer it. Due to this, Zip is extremely powerful because it allows manipulating several ranges in lockstep. For example, the following code sorts two arrays in parallel:int[] a = [ 1, 2, 3 ]; string[] b = [ "a", "b", "c" ]; sort!("a[0] > b[0]")(zip(a, b)); assert(a == [ 3, 2, 1 ]); assert(b == [ "c", "b", "a" ]);
- this(R rs, StoppingPolicy s = StoppingPolicy.shortest);
- Builds an object. Usually this is invoked indirectly by using the std.range.zip function.
- Returns true if the range is at end. The test depends on the stopping policy.
- Returns the current iterated element.
- Sets the front of all iterated ranges.
- Moves out the front.
- Returns the rightmost element.
- Moves out the back. Returns the rightmost element.
- Returns the current iterated element. Returns the rightmost element.
- Advances to the popFront element in all controlled ranges.
- Calls popBack for all controlled ranges.
- Returns the length of this range. Defined only if all ranges define length.
- Returns a slice of the range. Defined only if all range define slicing.
- Returns the nth element in the composite range. Defined if all ranges offer random access.
- Assigns to the nth element in the composite range. Defined if all ranges offer random access.
- Destructively reads the nth element in the composite range. Defined if all ranges offer random access.
- Dictates how iteration in a Zip should stop. By default stop at the end of the shortest of all ranges.
- Iterate multiple ranges in lockstep using a foreach loop. If only a single
range is passed in, the Lockstep aliases itself away. If the
ranges are of different lengths and s == StoppingPolicy.shortest
stop after the shortest range is empty. If the ranges are of different
lengths and s == StoppingPolicy.requireSameLength, throw an
exception. s may not be StoppingPolicy.longest, and passing this
will throw an exception.
BUGS:
If a range does not offer lvalue access, but ref is used in the foreach loop, it will be silently accepted but any modifications to the variable will not be propagated to the underlying range. Examples:auto arr1 = [1,2,3,4,5]; auto arr2 = [6,7,8,9,10]; foreach(ref a, ref b; lockstep(arr1, arr2)) { a += b; } assert(arr1 == [7,9,11,13,15]); // Lockstep also supports iterating with an index variable: foreach(index, a, b; lockstep(arr1, arr2)) { writefln("Index %s: a = %s, b = %s", index, a, b); }
- Creates a mathematical sequence given the initial values and a
recurrence function that computes the popFront value from the existing
values. The sequence comes in the form of an infinite forward
range. The type Recurrence itself is seldom used directly; most
often, recurrences are obtained by calling the function recurrence.
When calling recurrence, the function that computes the next
value is specified as a template argument, and the initial values in
the recurrence are passed as regular arguments. For example, in a
Fibonacci sequence, there are two initial values (and therefore a
state size of 2) because computing the popFront Fibonacci value needs the
past two values.
If the function is passed in string form, the state has name "a"
and the zero-based index in the recurrence has name "n". The
given string must return the desired value for a[n] given a[n
- 1], a[n - 2], a[n - 3],..., a[n - stateSize]. The
state size is dictated by the number of arguments passed to the call
to recurrence. The Recurrence class itself takes care of
managing the recurrence's state and shifting it appropriately.
Example:
// a[0] = 1, a[1] = 1, and compute a[n+1] = a[n-1] + a[n] auto fib = recurrence!("a[n-1] + a[n-2]")(1, 1); // print the first 10 Fibonacci numbers foreach (e; take(fib, 10)) { writeln(e); } // print the first 10 factorials foreach (e; take(recurrence!("a[n-1] * n")(1), 10)) { writeln(e); }
- Sequence is similar to Recurrence except that iteration is
presented in the so-called closed form. This means that the nth element in the series is
computable directly from the initial values and n itself. This
implies that the interface offered by Sequence is a random-access
range, as opposed to the regular Recurrence, which only offers
forward iteration.
The state of the sequence is stored as a Tuple so it can be
heterogeneous.
Example:
// a[0] = 1, a[1] = 2, a[n] = a[0] + n * a[1] auto odds = sequence!("a[0] + n * a[1]")(1, 2);
- Iota!(CommonType!(Unqual!(B),Unqual!(E)),S) iota(B, E, S)(B begin, E end, S step);
Iota!(CommonType!(Unqual!(B),Unqual!(E)),uint) iota(B, E)(B begin, E end);
Iota!(Unqual!(E),uint) iota(E)(E end);
struct Iota(N,S) if ((isIntegral!(N) || isPointer!(N)) && isIntegral!(S));
struct Iota(N,S) if (isFloatingPoint!(N) && isNumeric!(S)); - Returns a range that goes through the numbers begin, begin +
step, begin + 2 * step, ..., up to and excluding end. The range offered is a random access range. The two-arguments
version has step = 1.
Example:
auto r = iota(0, 10, 1); assert(equal(r, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9][])); r = iota(0, 11, 3); assert(equal(r, [0, 3, 6, 9][])); assert(r[2] == 6); auto rf = iota(0.0, 0.5, 0.1); assert(approxEqual(rf, [0.0, 0.1, 0.2, 0.3, 0.4]));
- Options for the FrontTransversal and Transversal ranges
(below).
- When transversed, the elements of a range of ranges are assumed to have different lengths (e.g. a jagged array).
- The transversal enforces that the elements of a range of ranges have all the same length (e.g. an array of arrays, all having the same length). Checking is done once upon construction of the transversal range.
- The transversal assumes, without verifying, that the elements of a range of ranges have all the same length. This option is useful if checking was already done from the outside of the range.
- Given a range of ranges, iterate transversally through the first
elements of each of the enclosed ranges.
Example:
int[][] x = new int[][2]; x[0] = [1, 2]; x[1] = [3, 4]; auto ror = frontTransversal(x); assert(equal(ror, [ 1, 3 ][]));
- this(RangeOfRanges input);
- Construction from an input.
- Forward range primitives.
- Slicing if offered if RangeOfRanges supports slicing and all the conditions for supporting indexing are met.
- Given a range of ranges, iterate transversally through the the nth element of each of the enclosed ranges. All elements of the
enclosing range must offer random access.
Example:
int[][] x = new int[][2]; x[0] = [1, 2]; x[1] = [3, 4]; auto ror = transversal(x, 1); assert(equal(ror, [ 2, 4 ][]));
- this(RangeOfRanges input, size_t n);
- Construction from an input and an index.
- Forward range primitives.
- Slicing if offered if RangeOfRanges supports slicing and all the conditions for supporting indexing are met.
- Moves the front of r out and returns it. Leaves r.front in a destroyable state that does not allocate any resources (usually equal to its .init value).
- Moves the back of r out and returns it. Leaves r.back in a destroyable state that does not allocate any resources (usually equal to its .init value).
- Moves element at index i of r out and returns it. Leaves r.front in a destroyable state that does not allocate any resources (usually equal to its .init value).
- These interfaces are intended to provide virtual function-based wrappers
around input ranges with element type E. This is useful where a well-defined
binary interface is required, such as when a DLL function or virtual function
needs to accept a generic range as a parameter. Note that
isInputRange and friends check for conformance to structural
interfaces, not for implementation of these interface types.
Examples:
class UsesRanges { void useRange(InputRange range) { // Function body. } } // Create a range type. auto squares = map!"a * a"(iota(10)); // Wrap it in an interface. auto squaresWrapped = inputRangeObject(squares); // Use it. auto usesRanges = new UsesRanges; usesRanges.useRange(squaresWrapped);
Limitations:
These interfaces are not capable of forwarding ref access to elements. Infiniteness of the wrapped range is not propagated. Length is not propagated in the case of non-random access ranges.- foreach iteration uses opApply, since one delegate call per loop
iteration is faster than three virtual function calls.
BUGS:
If a ref variable is provided as the loop variable, changes made to the loop variable will not be propagated to the underlying range. If the address of the loop variable is escaped, undefined behavior will result. This is related to DMD bug 2443.
- Interface for a forward range of type E.
- Interface for a bidirectional range of type E.
- Interface for a finite random access range of type E.
- Interface for an infinite random access range of type E.
- Adds assignable elements to InputRange.
- Adds assignable elements to ForwardRange.
- Adds assignable elements to BidirectionalRange.
- Adds assignable elements to RandomAccessFinite.
- Interface for an output range of type E. Usage is similar to the
InputRange interface and descendants.
- Implements the OutputRange interface for all types E and wraps the put method for each type E in a virtual function.
- Returns the interface type that best matches R.
- Implements the most derived interface that R works with and wraps all relevant range primitives in virtual functions. If R is already derived from the InputRange interface, aliases itself away.
- Convenience function for creating a InputRangeObject of the proper type.
- Convenience function for creating a OutputRangeObject with a base range
of type R that accepts types E.
Examples:
uint[] outputArray; auto app = appender(&outputArray); auto appWrapped = outputRangeObject!(uint, uint[])(app); static assert(is(typeof(appWrapped) : OutputRange!(uint[]))); static assert(is(typeof(appWrapped) : OutputRange!(uint)));
- Represents a sorted random-access range. In addition to the regular
range primitives, supports fast operations using binary search. To
obtain a SortedRange from an unsorted range r, use std.algorithm.sort which sorts r in place and returns the
corresponding SortedRange. To construct a SortedRange from a
range r that is known to be already sorted, use assumeSorted
described below.
Example:
auto a = [ 1, 2, 3, 42, 52, 64 ]; auto r = assumeSorted(a); assert(r.canFind(3)); assert(!r.canFind(32)); auto r1 = sort!"a > b"(a); assert(r1.canFind(3)); assert(!r1.canFind(32)); assert(r1.release() == [ 64, 52, 42, 3, 2, 1 ]);
SortedRange could accept ranges weaker than random-access, but it is unable to provide interesting functionality for them. Therefore, SortedRange is currently restricted to random-access ranges. No copy of the original range is ever made. If the underlying range is changed concurrently with its corresponding SortedRange in ways that break its sortedness, SortedRange will work erratically. Example:
auto a = [ 1, 2, 3, 42, 52, 64 ]; auto r = assumeSorted(a); assert(r.canFind(42)); swap(a[2], a[5]); // illegal to break sortedness of original range assert(!r.canFind(42)); // passes although it shouldn't
- Range primitives.
- Releases the controlled range and returns it.
- This function assumes that range r consists of a subrange r1
of elements e1 for which pred(e1, value) is true,
followed by a subrange r2 of elements e2 for which pred(e2, value) is false. Using this assumption, lowerBound
uses binary search to find r1, i.e. the left subrange on which
pred is always true. Performs Ο(log(r.length))
evaluations of pred. The precondition is not verified because it
would deteriorate function's complexity. It is possible that the types
of value and ElementType!(Range) are different, if the
predicate accepts them. See also STL's lower_bound.
Precondition:
find!(not!(pred))(r, value).length + find!(pred)(retro(r), value).length == r.length Example:
auto a = assumeSorted([ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ]); auto p = a.lowerBound(4); assert(p.release == [ 0, 1, 2, 3 ]);
- This function assumes that range r consists of a subrange r1
of elements e1 for which pred(e1, value) is true,
followed by a subrange r2 of elements e2 for which pred(e2, value) is false. Using this assumption, lowerBound
uses binary search to find r1, i.e. the left subrange on which
pred is always true. Performs Ο(log(r.length))
evaluations of pred. The precondition is not verified because it
would deteriorate function's complexity. It is possible that the types
of value and ElementType!(Range) are different, if the
predicate accepts them. See also STL's lower_bound.
Precondition:
find!(not!(pred))(r, value).length + find!(pred)(retro(r), value).length == r.length Example:
auto a = assumeSorted([ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ]); auto p = a.lowerBound(4); assert(p.release == [ 0, 1, 2, 3 ]);
- This function assumes that range r consists of a subrange r1
of elements e1 for which pred(value, e1) is false,
followed by a subrange r2 of elements e2 for which pred(value, e2) is true. (Note the differences in subrange
definition and argument order for pred compared to lowerBound.) Using this assumption, upperBound uses binary
search to find r2, i.e. the right subrange on which pred is
always true. Performs Ο(log(r.length)) evaluations of pred. The precondition is not verified because it would deteriorate
function's complexity. It is possible that the types of value and
ElementType!(Range) are different, if the predicate accepts
them. See also STL's upper_bound.
Precondition:
find!(pred)(r, value).length + find!(not!(pred))(retro(r), value).length == r.length Example:
auto a = assumeSorted([ 1, 2, 3, 3, 3, 4, 4, 5, 6 ]); auto p = a.upperBound(3); assert(p == [4, 4, 5, 6]);
- This function assumes that range r consists of a subrange r1
of elements e1 for which pred(value, e1) is false,
followed by a subrange r2 of elements e2 for which pred(value, e2) is true. (Note the differences in subrange
definition and argument order for pred compared to lowerBound.) Using this assumption, upperBound uses binary
search to find r2, i.e. the right subrange on which pred is
always true. Performs Ο(log(r.length)) evaluations of pred. The precondition is not verified because it would deteriorate
function's complexity. It is possible that the types of value and
ElementType!(Range) are different, if the predicate accepts
them. See also STL's upper_bound.
Precondition:
find!(pred)(r, value).length + find!(not!(pred))(retro(r), value).length == r.length Example:
auto a = assumeSorted([ 1, 2, 3, 3, 3, 4, 4, 5, 6 ]); auto p = a.upperBound(3); assert(p == [4, 4, 5, 6]);
- Assuming a range satisfying both preconditions for lowerBound!(pred)(r, value) and upperBound!(pred)(r, value), the
call equalRange!(pred)(r, v) returns the subrange containing all
elements e for which both pred(e, value) and pred(value,
e) evaluate to false. Performs Ο(log(r.length))
evaluations of pred. See also STL's equal_range.
Precondition:
find!(not!(pred))(r, value).length + find!(pred)(retro(r), value).length == r.length && find!(pred)(r, value).length + find!(not!(pred))(retro(r), value).length == r.length Example:
auto a = [ 1, 2, 3, 3, 3, 4, 4, 5, 6 ]; auto r = equalRange(a, 3); assert(r == [ 3, 3, 3 ]);
- Assuming a range satisfying both preconditions for lowerBound!(pred)(r, value) and upperBound!(pred)(r, value), the
call equalRange!(pred)(r, v) returns the subrange containing all
elements e for which both pred(e, value) and pred(value,
e) evaluate to false. Performs Ο(log(r.length))
evaluations of pred. See also STL's equal_range.
Precondition:
find!(not!(pred))(r, value).length + find!(pred)(retro(r), value).length == r.length && find!(pred)(r, value).length + find!(not!(pred))(retro(r), value).length == r.length Example:
auto a = [ 1, 2, 3, 3, 3, 4, 4, 5, 6 ]; auto r = equalRange(a, 3); assert(r == [ 3, 3, 3 ]);
- Returns true if and only if value can be found in range, which is assumed to be sorted. Performs Ο(log(r.length))
evaluations of pred. See also STL's binary_search.
- Returns true if and only if value can be found in range, which is assumed to be sorted. Performs Ο(log(r.length)) evaluations of pred. See also STL's binary_search.