syft/internal/index

internal/index

A key-split (radix) index over strings, and a forward/reverse pair of them that answers prefix and suffix lookups. Ported from a prototype directory-scan package and kept close to the original so the two can be diffed.

Types

• KeySplitIndex[T] / Node[T]: a radix tree. Each node holds at most one value and splits its children on the longest common prefix of their keys, so pom.xml and pom.properties share a pom. node. Reads take a read lock per node; writes upgrade to a write lock only where the tree changes. KeySplitIndex also marshals to and from a flat JSON object of key → value.
• PrefixSuffix[T]: two KeySplitIndex values, one keyed by the string and one by its reverse, so ByPrefix("pom") and BySuffix(".jar") are both a single descent followed by a collect.

Operations

call	answers
Get(key)	the value at exactly key
Set(key, v) / Update(key, fn)	store, or read-modify-write, the value at key
ByPrefix(p)	every value whose key starts with p
BySuffix(s) (PrefixSuffix only)	every value whose key ends with s

Values are whatever the caller stores; internal/archive stores []*node per base name because a name repeats across directories.

Where it is used

internal/archive.Index keeps one PrefixSuffix[[]*node] of files by base name. A cataloger glob whose last segment is a literal, *suffix or prefix* (nearly all of them: **/*.jar, **/pom.properties) is answered from it instead of by walking every path.

Notes

• Lookups are byte-wise; reverse works on runes so a multi-byte name reverses correctly.
• lock.go returns unlock functions rather than exposing Unlock, which is how a node tells a read lock from a write lock when deciding whether to upgrade.
• _find, _collect and _makeNodeP are the prototype's internals and are left with its naming.