6b21ad9922
Everywhere including examples, external interop APIs, bindings generators
code and in other valuable places. A couple of `interface{}` usages are
intentionally left in the CHANGELOG.md, documentation and tests.
87 lines
5.3 KiB
Go
87 lines
5.3 KiB
Go
package smartcontract
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import (
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"fmt"
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"github.com/nspcc-dev/neo-go/pkg/core/interop/interopnames"
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"github.com/nspcc-dev/neo-go/pkg/io"
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"github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag"
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"github.com/nspcc-dev/neo-go/pkg/util"
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"github.com/nspcc-dev/neo-go/pkg/vm/emit"
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"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
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)
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// CreateCallAndUnwrapIteratorScript creates a script that calls 'operation' method
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// of the 'contract' with the specified arguments. This method is expected to return
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// an iterator that then is traversed (using iterator.Next) with values (iterator.Value)
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// extracted and added into array. At most maxIteratorResultItems number of items is
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// processed this way (and this number can't exceed VM limits), the result of the
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// script is an array containing extracted value elements. This script can be useful
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// for interactions with RPC server that have iterator sessions disabled.
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func CreateCallAndUnwrapIteratorScript(contract util.Uint160, operation string, maxIteratorResultItems int, params ...any) ([]byte, error) {
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script := io.NewBufBinWriter()
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emit.Int(script.BinWriter, int64(maxIteratorResultItems))
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emit.AppCall(script.BinWriter, contract, operation, callflag.All, params...) // The System.Contract.Call itself, it will push Iterator on estack.
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emit.Opcodes(script.BinWriter, opcode.NEWARRAY0) // Push new empty array to estack. This array will store iterator's elements.
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// Start the iterator traversal cycle.
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iteratorTraverseCycleStartOffset := script.Len()
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emit.Opcodes(script.BinWriter, opcode.OVER) // Load iterator from 1-st cell of estack.
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emit.Syscall(script.BinWriter, interopnames.SystemIteratorNext) // Call System.Iterator.Next, it will pop the iterator from estack and push `true` or `false` to estack.
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jmpIfNotOffset := script.Len()
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emit.Instruction(script.BinWriter, opcode.JMPIFNOT, // Pop boolean value (from the previous step) from estack, if `false`, then iterator has no more items => jump to the end of program.
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[]byte{
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0x00, // jump to loadResultOffset, but we'll fill this byte after script creation.
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})
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emit.Opcodes(script.BinWriter, opcode.DUP, // Duplicate the resulting array from 0-th cell of estack and push it to estack.
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opcode.PUSH2, opcode.PICK) // Pick iterator from the 2-nd cell of estack.
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emit.Syscall(script.BinWriter, interopnames.SystemIteratorValue) // Call System.Iterator.Value, it will pop the iterator from estack and push its current value to estack.
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emit.Opcodes(script.BinWriter, opcode.APPEND) // Pop iterator value and the resulting array from estack. Append value to the resulting array. Array is a reference type, thus, value stored at the 1-th cell of local slot will also be updated.
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emit.Opcodes(script.BinWriter, opcode.DUP, // Duplicate the resulting array from 0-th cell of estack and push it to estack.
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opcode.SIZE, // Pop array from estack and push its size to estack.
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opcode.PUSH3, opcode.PICK, // Pick maxIteratorResultItems from the 3-d cell of estack.
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opcode.GE) // Compare len(arr) and maxIteratorResultItems
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jmpIfMaxReachedOffset := script.Len()
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emit.Instruction(script.BinWriter, opcode.JMPIF, // Pop boolean value (from the previous step) from estack, if `false`, then max array elements is reached => jump to the end of program.
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[]byte{
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0x00, // jump to loadResultOffset, but we'll fill this byte after script creation.
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})
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jmpOffset := script.Len()
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emit.Instruction(script.BinWriter, opcode.JMP, // Jump to the start of iterator traverse cycle.
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[]byte{
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uint8(iteratorTraverseCycleStartOffset - jmpOffset), // jump to iteratorTraverseCycleStartOffset; offset is relative to JMP position.
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})
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// End of the program: push the result on stack and return.
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loadResultOffset := script.Len()
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emit.Opcodes(script.BinWriter, opcode.NIP, // Remove iterator from the 1-st cell of estack
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opcode.NIP) // Remove maxIteratorResultItems from the 1-st cell of estack, so that only resulting array is left on estack.
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if err := script.Err; err != nil {
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return nil, fmt.Errorf("emitting iterator unwrapper script: %w", err)
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}
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// Fill in JMPIFNOT instruction parameter.
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bytes := script.Bytes()
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bytes[jmpIfNotOffset+1] = uint8(loadResultOffset - jmpIfNotOffset) // +1 is for JMPIFNOT itself; offset is relative to JMPIFNOT position.
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// Fill in jmpIfMaxReachedOffset instruction parameter.
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bytes[jmpIfMaxReachedOffset+1] = uint8(loadResultOffset - jmpIfMaxReachedOffset) // +1 is for JMPIF itself; offset is relative to JMPIF position.
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return bytes, nil
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}
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// CreateCallScript returns a script that calls contract's method with
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// the specified parameters. Whatever this method returns remains on the stack.
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// See also (*Builder).InvokeMethod.
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func CreateCallScript(contract util.Uint160, method string, params ...any) ([]byte, error) {
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b := NewBuilder()
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b.InvokeMethod(contract, method, params...)
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return b.Script()
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}
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// CreateCallWithAssertScript returns a script that calls contract's method with
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// the specified parameters expecting a Boolean value to be return that then is
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// used for ASSERT. See also (*Builder).InvokeWithAssert.
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func CreateCallWithAssertScript(contract util.Uint160, method string, params ...any) ([]byte, error) {
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b := NewBuilder()
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b.InvokeWithAssert(contract, method, params...)
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return b.Script()
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}
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