repository

package
Version: v2.2.3 Latest Latest
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Published: Jul 8, 2022 License: BSD-3-Clause Imports: 11 Imported by: 6

Documentation

Overview

Package repository provides primitives for working with storage repositories.

Index

Constants

This section is empty.

Variables

View Source
var (
	// ErrOperationNotSupported may be thrown by certain functions in the storage
	// or repository packages which operate on URIs if an operation is attempted
	// that is not supported for the scheme relevant to the URI, normally because
	// the underlying repository has either not implemented the relevant function,
	// or has explicitly returned this error.
	//
	// Since: 2.0
	ErrOperationNotSupported = errors.New("operation not supported for this URI")

	// ErrURIRoot should be thrown by fyne.URI implementations when the caller
	// attempts to take the parent of the root. This way, downstream code that
	// wants to programmatically walk up a URIs parent's will know when to stop
	// iterating.
	//
	// Since: 2.0
	ErrURIRoot = errors.New("cannot take the parent of the root element in a URI")
)

Functions

func GenericChild

func GenericChild(u fyne.URI, component string) (fyne.URI, error)

GenericChild can be used as a common-case implementation of HierarchicalRepository.Child(). It will create a child URI by separating the URI into it's component parts as described in IETF RFC 3986, then appending "/" + component to the path, then concatenating the result and parsing it as a new URI.

NOTE: this function should not be called except by an implementation of the Repository interface - using this for unknown URIs may break.

Since: 2.0

func GenericCopy

func GenericCopy(source fyne.URI, destination fyne.URI) error

GenericCopy can be used a common-case implementation of CopyableRepository.Copy(). It will perform the copy by obtaining a reader for the source URI, a writer for the destination URI, then writing the contents of the source to the destination.

For obvious reasons, the destination URI must have a registered WritableRepository.

NOTE: this function should not be called except by an implementation of the Repository interface - using this for unknown URIs may break.

Since: 2.0

func GenericMove

func GenericMove(source fyne.URI, destination fyne.URI) error

GenericMove can be used a common-case implementation of MovableRepository.Move(). It will perform the move by obtaining a reader for the source URI, a writer for the destination URI, then writing the contents of the source to the destination. Following this, the source will be deleted using WritableRepository.Delete.

For obvious reasons, the source and destination URIs must both be writable.

NOTE: this function should not be called except by an implementation of the Repository interface - using this for unknown URIs may break.

Since: 2.0

func GenericParent

func GenericParent(u fyne.URI) (fyne.URI, error)

GenericParent can be used as a common-case implementation of HierarchicalRepository.Parent(). It will create a parent URI based on IETF RFC3986.

In short, the URI is separated into it's component parts, the path component is split along instances of '/', and the trailing element is removed. The result is concatenated and parsed as a new URI.

If the URI path is empty or '/', then a nil URI is returned, along with ErrURIRoot.

NOTE: this function should not be called except by an implementation of the Repository interface - using this for unknown URIs may break.

Since: 2.0

func NewFileURI

func NewFileURI(path string) fyne.URI

NewFileURI implements the back-end logic to storage.NewFileURI, which you should use instead. This is only here because other functions in repository need to call it, and it prevents a circular import.

Since: 2.0

func ParseURI

func ParseURI(s string) (fyne.URI, error)

ParseURI implements the back-end logic for storage.ParseURI, which you should use instead. This is only here because other functions in repository need to call it, and it prevents a circular import.

Since: 2.0

func Register

func Register(scheme string, repository Repository)

Register registers a storage repository so that operations on URIs of the registered scheme will use methods implemented by the relevant repository implementation.

Since: 2.0

Types

type CopyableRepository

type CopyableRepository interface {
	Repository

	// Copy will be used to implement calls to storage.Copy() for the
	// registered scheme of this repository.
	//
	// A generic implementation is provided by GenericCopy().
	//
	// NOTE: the first parameter is the source, the second is the
	// destination.
	//
	// NOTE: if storage.Copy() is given two URIs of different schemes, it
	// is possible that only the source URI will be of the type this
	// repository is registered to handle. In such cases, implementations
	// are suggested to fail-over to GenericCopy().
	//
	// Since: 2.0
	Copy(fyne.URI, fyne.URI) error
}

CopyableRepository is an extension of the Repository interface which also supports copying referenced resources from one URI to another.

Since: 2.0

type CustomURIRepository

type CustomURIRepository interface {
	Repository

	// ParseURI will be used to implement calls to storage.ParseURI()
	// for the registered scheme of this repository.
	ParseURI(string) (fyne.URI, error)
}

CustomURIRepository is an extension of the repository interface which allows the behavior of storage.ParseURI to be overridden. This is only needed if you wish to generate custom URI types, rather than using Fyne's URI implementation and net/url based parsing.

NOTE: even for URIs with non-RFC3986-compliant encoding, the URI MUST begin with 'scheme:', or storage.ParseURI() will not be able to determine which storage repository to delegate to for parsing.

Since: 2.0

type HierarchicalRepository

type HierarchicalRepository interface {
	Repository

	// Parent will be used to implement calls to storage.Parent() for the
	// registered scheme of this repository.
	//
	// A generic implementation is provided in GenericParent(), which
	// is based on the RFC3986 definition of a URI parent.
	//
	// Since: 2.0
	Parent(fyne.URI) (fyne.URI, error)

	// Child will be used to implement calls to storage.Child() for
	// the registered scheme of this repository.
	//
	// A generic implementation is provided in GenericParent(), which
	// is based on RFC3986.
	//
	// Since: 2.0
	Child(fyne.URI, string) (fyne.URI, error)
}

HierarchicalRepository is an extension of the Repository interface which also supports determining the parent and child items of a URI.

Since: 2.0

type ListableRepository

type ListableRepository interface {
	Repository

	// CanList will be used to implement calls to storage.Listable() for
	// the registered scheme of this repository.
	//
	// Since: 2.0
	CanList(u fyne.URI) (bool, error)

	// List will be used to implement calls to storage.List() for the
	// registered scheme of this repository.
	//
	// Since: 2.0
	List(u fyne.URI) ([]fyne.URI, error)

	// CreateListable will be used to implement calls to
	// storage.CreateListable() for the registered scheme of this
	// repository.
	//
	// Since: 2.0
	CreateListable(u fyne.URI) error
}

ListableRepository is an extension of the Repository interface which also supports obtaining directory listings (generally analogous to a directory listing) for URIs of the scheme it is registered to.

Since: 2.0

type MovableRepository

type MovableRepository interface {
	Repository

	// Move will be used to implement calls to storage.Move() for the
	// registered scheme of this repository.
	//
	// A generic implementation is provided by GenericMove().
	//
	// NOTE: the first parameter is the source, the second is the
	// destination.
	//
	// NOTE: if storage.Move() is given two URIs of different schemes, it
	// is possible that only the source URI will be of the type this
	// repository is registered to handle. In such cases, implementations
	// are suggested to fail-over to GenericMove().
	//
	// Since: 2.0
	Move(fyne.URI, fyne.URI) error
}

MovableRepository is an extension of the Repository interface which also supports moving referenced resources from one URI to another.

Note: both Moveable and Movable are correct spellings, but Movable is newer and more accepted. Source: https://grammarist.com/spelling/movable-moveable/

Since: 2.0

type Repository

type Repository interface {

	// Exists will be used to implement calls to storage.Exists() for the
	// registered scheme of this repository.
	//
	// Since: 2.0
	Exists(u fyne.URI) (bool, error)

	// Reader will be used to implement calls to storage.Reader()
	// for the registered scheme of this repository.
	//
	// Since: 2.0
	Reader(u fyne.URI) (fyne.URIReadCloser, error)

	// CanRead will be used to implement calls to storage.CanRead() for the
	// registered scheme of this repository.
	//
	// Since: 2.0
	CanRead(u fyne.URI) (bool, error)

	// Destroy is called when the repository is un-registered from a given
	// URI scheme.
	//
	// The string parameter will be the URI scheme that the repository was
	// registered for. This may be useful for repositories that need to
	// handle more than one URI scheme internally.
	//
	// Since: 2.0
	Destroy(string)
}

Repository represents a storage repository, which is a set of methods which implement specific functions on a URI. Repositories are registered to handle specific URI schemes, and the higher-level functions that operate on URIs internally look up an appropriate method from the relevant Repository.

The repository interface includes only methods which must be implemented at a minimum. Without implementing all of the methods in this interface, a URI would not be usable in a useful way. Additional functionality can be exposed by using interfaces which extend Repository.

Repositories are registered to handle a specific URI scheme (or schemes) using the Register() method. When a higher-level URI function such as storage.Copy() is called, the storage package will internally look up the repository associated with the scheme of the URI, then it will use a type assertion to check if the repository implements CopyableRepository. If so, the Copy() function will be run from the repository, otherwise storage.Copy() will return NotSupportedError. This works similarly for all other methods in repository-related interfaces.

Note that a repository can be registered for multiple URI schemes. In such cases, the repository must internally select and implement the correct behavior for each URI scheme.

A repository will only ever need to handle URIs with schemes for which it was registered, with the exception that functions with more than 1 operand such as Copy() and Move(), in which cases only the first operand is guaranteed to match a scheme for which the repository is registered.

NOTE: most developers who use Fyne should *not* generally attempt to call repository methods directly. You should use the methods in the storage package, which will automatically detect the scheme of a URI and call into the appropriate repository.

Since: 2.0

func ForScheme

func ForScheme(scheme string) (Repository, error)

ForScheme returns the Repository instance which is registered to handle URIs of the given scheme.

NOTE: this function is intended to be used specifically by the storage package. It generally should not be used outside of the fyne package - instead you should use the methods in the storage package.

Since: 2.0

func ForURI

func ForURI(u fyne.URI) (Repository, error)

ForURI returns the Repository instance which is registered to handle URIs of the given scheme. This is a helper method that calls ForScheme() on the scheme of the given URI.

NOTE: this function is intended to be used specifically by the storage package. It generally should not be used outside of the fyne package - instead you should use the methods in the storage package.

Since: 2.0

type WritableRepository

type WritableRepository interface {
	Repository

	// Writer will be used to implement calls to storage.WriterTo() for
	// the registered scheme of this repository.
	//
	// Since: 2.0
	Writer(u fyne.URI) (fyne.URIWriteCloser, error)

	// CanWrite will be used to implement calls to storage.CanWrite() for
	// the registered scheme of this repository.
	//
	// Since: 2.0
	CanWrite(u fyne.URI) (bool, error)

	// Delete will be used to implement calls to storage.Delete() for the
	// registered scheme of this repository.
	//
	// Since: 2.0
	Delete(u fyne.URI) error
}

WritableRepository is an extension of the Repository interface which also supports obtaining a writer for URIs of the scheme it is registered to.

Since: 2.0

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