Documentation

Overview

    Package noder provide an interface for defining nodes in a merkletrie, their hashes and their paths (a noders and its ancestors).

    The hasher interface is easy to implement naively by elements that already have a hash, like git blobs and trees. More sophisticated implementations can implement the Equal function in exotic ways though: for instance, comparing the modification time of directories in a filesystem.

    Index

    Constants

    This section is empty.

    Variables

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    var NoChildren = []Noder{}

      NoChildren represents the children of a noder without children.

      Functions

      This section is empty.

      Types

      type Equal

      type Equal func(a, b Hasher) bool

        Equal functions take two hashers and return if they are equal.

        These functions are expected to be faster than reflect.Equal or reflect.DeepEqual because they can compare just the hash of the objects, instead of their contents, so they are expected to be O(1).

        type Hasher

        type Hasher interface {
        	Hash() []byte
        }

          Hasher interface is implemented by types that can tell you their hash.

          type Noder

          type Noder interface {
          	Hasher
          	fmt.Stringer // for testing purposes
          	// Name returns the name of an element (relative, not its full
          	// path).
          	Name() string
          	// IsDir returns true if the element is a directory-like node or
          	// false if it is a file-like node.
          	IsDir() bool
          	// Children returns the children of the element.  Note that empty
          	// directory-like noders and file-like noders will both return
          	// NoChildren.
          	Children() ([]Noder, error)
          	// NumChildren returns the number of children this element has.
          	//
          	// This method is an optimization: the number of children is easily
          	// calculated as the length of the value returned by the Children
          	// method (above); yet, some implementations will be able to
          	// implement NumChildren in O(1) while Children is usually more
          	// complex.
          	NumChildren() (int, error)
          }

            The Noder interface is implemented by the elements of a Merkle Trie.

            There are two types of elements in a Merkle Trie:

            - file-like nodes: they cannot have children.

            - directory-like nodes: they can have 0 or more children and their hash is calculated by combining their children hashes.

            type Path

            type Path []Noder

              Path values represent a noder and its ancestors. The root goes first and the actual final noder the path is referring to will be the last.

              A path implements the Noder interface, redirecting all the interface calls to its final noder.

              Paths build from an empty Noder slice are not valid paths and should not be used.

              func (Path) Children

              func (p Path) Children() ([]Noder, error)

                Children returns the children of the final noder in the path.

                func (Path) Compare

                func (p Path) Compare(other Path) int

                  Compare returns -1, 0 or 1 if the path p is smaller, equal or bigger than other, in "directory order"; for example:

                  "a" < "b" "a/b/c/d/z" < "b" "a/b/a" > "a/b"

                  func (Path) Hash

                  func (p Path) Hash() []byte

                    Hash returns the hash of the final noder of the path.

                    func (Path) IsDir

                    func (p Path) IsDir() bool

                      IsDir returns if the final noder of the path is a directory-like noder.

                      func (Path) Last

                      func (p Path) Last() Noder

                        Last returns the final noder in the path.

                        func (Path) Name

                        func (p Path) Name() string

                          Name returns the name of the final noder of the path.

                          func (Path) NumChildren

                          func (p Path) NumChildren() (int, error)

                            NumChildren returns the number of children the final noder of the path has.

                            func (Path) String

                            func (p Path) String() string

                              String returns the full path of the final noder as a string, using "/" as the separator.

                              Source Files