struct Pf::UPath32

Overview

An immutable vector of UInt32s (here called indices) with tree path- specific optimizations.

path = Pf::UPath32[100, 20]
path.append(3) # => UPath32[100, 20, 3]
path.append(7) # => UPath32[100, 20, 7]
path           # => UPath32[100, 20]

Included Modules

Defined in:

permafrost/upath32.cr

Constructors

Instance Method Summary

Instance methods inherited from module Enumerable(UInt32)

to_pf_bidi to_pf_bidi, to_pf_map(& : T -> Tuple(K, V)) : Pf::Map(K, V) forall K, V
to_pf_map to_pf_map, to_pf_set : Pf::Set(T) to_pf_set, to_pf_uset32 : Pf::USet32 to_pf_uset32

Constructor Detail

def self.[] : UPath32 #

Constructs an empty path.


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def self.[](*ns : UInt32) : UPath32 #

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def self.end : UPath32 #

Returns the sentinel End path.


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Instance Method Detail

def ==(other : UPath32) : Bool #

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def [](index : Int) : UInt32 #

See Indexable#[](index : Int).


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def []?(index : Int) : UInt32 | Nil #

See Indexable#[]?(index : Int).


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def append(step : UInt32) : UPath32 #

Inserts step at the back of this path. Returns the modified copy.


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def dense? : Bool #

Returns true if the underlying representation of this path is dense.

As an optimization, we store small paths inline, packing them in 57 bits plus 4-bit size.

The shape of the "path gamut" for this representation is currently 14-9-8-6-4-4-4-4. Paths that are outside of this "gamut" are transferred to (or constructed on) the GC heap (#sparse?).

  • The first index receives a larger number of bits, because indices near the root are usually large.
  • Successive indices receive a smaller number of bits, because nodes closer to the root are expected to be large, but smaller than their predecessor.

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def each(& : UInt32 -> ) #

Yields each index in this path in front-to-back order.


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def end? : Bool #

Returns true if this path is the sentinel End path.

Sentinel End marker useful in traversals that must distinguish entering the root from reentering it at the end of traversal.


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def hash(hasher) #
Description copied from struct Struct

See Object#hash(hasher)


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def index? : Bool #

Returns true if the underlying representation of this path is an index.

Index optimizes singleton UPath32's, which can be encountered when one uses UPath32 as an index, or when it happens to be used as one (e.g. skipping over root terms during DFS or BFS).


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def inspect(io) #

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def last : UInt32 #

Returns the last index in this path. Raises IndexError if this path is empty.


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def last? : UInt32 | Nil #

Returns the last index in this path, or nil if this path is empty.


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def prior : UPath32 #

Returns the part of this path before the last index. If this path is empty, returns an empty path.


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def size : Int32 #

Returns the number of indices in this path as an index within zero or positive Int32 bounds.


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def sparse? : Bool #

Returns true if the underlying representation of this path is sparse.

Sparse paths are stored on the GC heap.


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def usize : UInt32 #

Returns the number of indices in this path as an index within UInt32 bounds.


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