Bodu.Collections.Extensions Namespace

Package

Bodu.Core 1.0.1

Purpose

Bodu.Collections.Extensions holds the non-generic / shape-agnostic enumeration helpers that complement Bodu.Collections.Generic.Extensions. Reach for this namespace when you want recursive-descent helpers or count helpers that work against IEnumerable rather than IEnumerable<T>.

Key types

• IEnumerableExtensions - CountOrDefault, RecursiveSelect for non-generic shapes.
• RecursiveSelectControl - [Flags] value returned by a recursion-control callback to decide, per element, whether to yield it, descend into its children, and whether to stop: the primitive flags None, Yield, Recurse, Skip, Break, Exit, and the named combinations YieldOnly, RecurseOnly, YieldAndRecurse, SkipOnly, SkipAndRecurse, YieldAndBreak, SkipAndBreak, YieldAndExit, SkipAndExit. Shared with the typed RecursiveSelect overloads in Bodu.Collections.Generic.Extensions.

Example

using Bodu.Collections.Extensions;

// Counts a non-generic IEnumerable - O(1) when the source is an ICollection, otherwise it enumerates.
int n = source.CountOrDefault();

// Recursive-select over a non-generic IEnumerable: the child selector and the result are untyped.
IEnumerable flattened = root.RecursiveSelect(node => ((Node)node).Children);

// Fine-grained descent control on the non-generic surface: yield visible nodes and descend into
// them, skip invisible subtrees, and stop the whole walk at the first node flagged as terminal.
IEnumerable visible = root.RecursiveSelect(
    node => ((Node)node).Children,
    (node, index, depth) => node,
    node => ((Node)node).IsTerminal ? RecursiveSelectControl.YieldAndExit
          : ((Node)node).IsVisible  ? RecursiveSelectControl.YieldAndRecurse
                                    : RecursiveSelectControl.SkipOnly);

When the source is already an IEnumerable<T>, prefer the typed overloads in Bodu.Collections.Generic.Extensions - the same RecursiveSelectControl vocabulary with strongly typed selectors and an IEnumerable<TResult> result.

Notes

• Counterpart to the generic surface. Sequence helpers parameterised on T live in Bodu.Collections.Generic.Extensions; this namespace covers the cases where the source is shape-agnostic.
• Packaging. This extension namespace ships in the Bodu.Core package; the concrete collection types in the sibling Bodu.Collections.* namespaces ship in the Bodu.Collections package, except the thread-safe Bodu.Collections.Generic.Concurrent variants, which ship in Bodu.Collections.Concurrent.
• See also: the Bodu.Core introduction, the companion Bodu.Collections.Generic.Extensions namespace.

Classes

IEnumerableExtensions

Provides operations over the non-generic IEnumerable surface - counting without enumerating where the source is already a collection, and walking heterogeneous tree structures recursively - for code that has to deal with reflection-shaped or legacy sequences.

Enums

RecursiveSelectControl

Represents composable control flags for how an element is processed during recursive selection.