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101 lines
4.6 KiB
Go
101 lines
4.6 KiB
Go
/*
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Package storage provides functions to access and modify contract's storage.
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Neo storage's model follows simple key-value DB pattern, this storage is a part
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of blockchain state, so you can use it between various invocations of the same
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contract.
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*/
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package storage
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import (
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"github.com/nspcc-dev/neo-go/pkg/interop/iterator"
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"github.com/nspcc-dev/neo-go/pkg/interop/neogointernal"
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)
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// Context represents storage context that is mandatory for Put/Get/Delete
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// operations. It's an opaque type that can only be created properly by
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// GetContext, GetReadOnlyContext or ConvertContextToReadOnly. It's similar
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// to Neo .net framework's StorageContext class.
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type Context struct{}
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// FindFlags represents parameters to `Find` iterator.
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type FindFlags byte
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const (
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// None is default option. Iterator values are key-value pairs.
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None FindFlags = 0
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// KeysOnly is used for iterating over keys.
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KeysOnly FindFlags = 1 << 0
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// RemovePrefix is used for stripping 1-byte prefix from keys.
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RemovePrefix FindFlags = 1 << 1
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// ValuesOnly is used for iterating over values.
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ValuesOnly FindFlags = 1 << 2
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// DeserializeValues is used for deserializing values on-the-fly.
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// It can be combined with other options.
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DeserializeValues FindFlags = 1 << 3
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// PickField0 is used to get first field in a serialized struct or array.
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PickField0 FindFlags = 1 << 4
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// PickField1 is used to get second field in a serialized struct or array.
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PickField1 FindFlags = 1 << 5
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)
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// ConvertContextToReadOnly returns new context from the given one, but with
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// writing capability turned off, so that you could only invoke Get and Find
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// using this new Context. If Context is already read-only this function is a
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// no-op. It uses `System.Storage.AsReadOnly` syscall.
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func ConvertContextToReadOnly(ctx Context) Context {
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return neogointernal.Syscall1("System.Storage.AsReadOnly", ctx).(Context)
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}
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// GetContext returns current contract's (that invokes this function) storage
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// context. It uses `System.Storage.GetContext` syscall.
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func GetContext() Context {
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return neogointernal.Syscall0("System.Storage.GetContext").(Context)
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}
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// GetReadOnlyContext returns current contract's (that invokes this function)
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// storage context in read-only mode, you can use this context for Get and Find
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// functions, but using it for Put and Delete will fail. It uses
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// `System.Storage.GetReadOnlyContext` syscall.
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func GetReadOnlyContext() Context {
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return neogointernal.Syscall0("System.Storage.GetReadOnlyContext").(Context)
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}
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// Put saves given value with given key in the storage using given Context.
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// Even though it accepts interface{} for both, you can only pass simple types
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// there like string, []byte, int or bool (not structures or slices of more
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// complex types). To put more complex types there serialize them first using
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// runtime.Serialize. This function uses `System.Storage.Put` syscall.
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func Put(ctx Context, key interface{}, value interface{}) {
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neogointernal.Syscall3NoReturn("System.Storage.Put", ctx, key, value)
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}
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// PutEx is an advanced version of Put which saves given value with given key
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// and given ReadOnly flag in the storage using given Context. `flag` argument
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// can either be odd for constant storage items or even for variable storage items.
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// Refer to Put function description for details on how to pass the remaining
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// arguments. This function uses `System.Storage.PutEx` syscall.
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func PutEx(ctx Context, key interface{}, value interface{}, flag int64) {
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neogointernal.Syscall4NoReturn("System.Storage.PutEx", ctx, key, value, flag)
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}
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// Get retrieves value stored for the given key using given Context. See Put
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// documentation on possible key and value types. If the value is not present in
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// the database it returns nil. This function uses `System.Storage.Get` syscall.
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func Get(ctx Context, key interface{}) interface{} {
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return neogointernal.Syscall2("System.Storage.Get", ctx, key)
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}
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// Delete removes key-value pair from storage by the given key using given
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// Context. See Put documentation on possible key types. This function uses
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// `System.Storage.Delete` syscall.
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func Delete(ctx Context, key interface{}) {
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neogointernal.Syscall2NoReturn("System.Storage.Delete", ctx, key)
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}
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// Find returns an iterator.Iterator over key-value pairs in the given Context
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// that match the given key (contain it as a prefix). See Put documentation on
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// possible key types and iterator package documentation on how to use the
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// returned value. This function uses `System.Storage.Find` syscall.
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func Find(ctx Context, key interface{}, options FindFlags) iterator.Iterator {
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return neogointernal.Syscall3("System.Storage.Find", ctx, key, options).(iterator.Iterator)
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}
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