github.com/SmartMeshFoundation/Spectrum@v0.0.0-20220621030607-452a266fee1e/eth/tracers/tracers.go (about)

     1  // Copyright 2017 The Spectrum Authors
     2  // This file is part of the Spectrum library.
     3  //
     4  // The Spectrum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The Spectrum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the Spectrum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  // Package tracers is a collection of JavaScript transaction tracers.
    18  package tracers
    19  
    20  import (
    21  	"encoding/json"
    22  	"errors"
    23  	"github.com/SmartMeshFoundation/Spectrum/common"
    24  	"github.com/SmartMeshFoundation/Spectrum/core/vm"
    25  )
    26  
    27  var all = make(map[string]string)
    28  
    29  // tracer retrieves a specific JavaScript tracer by name.
    30  func tracer(name string) (string, bool) {
    31  	if tracer, ok := all[name]; ok {
    32  		return tracer, true
    33  	}
    34  	return "", false
    35  }
    36  
    37  // Context contains some contextual infos for a transaction execution that is not
    38  // available from within the EVM object.
    39  type Context struct {
    40  	BlockHash common.Hash // Hash of the block the tx is contained within (zero if dangling tx or call)
    41  	TxIndex   int         // Index of the transaction within a block (zero if dangling tx or call)
    42  	TxHash    common.Hash // Hash of the transaction being traced (zero if dangling call)
    43  }
    44  
    45  type Tracer interface {
    46  	vm.EVMLogger
    47  	GetResult() (json.RawMessage, error)
    48  	// Stop terminates execution of the tracer at the first opportune moment.
    49  	Stop(err error)
    50  }
    51  
    52  type lookupFunc func(string, *Context) (Tracer, error)
    53  
    54  var (
    55  	lookups []lookupFunc
    56  )
    57  
    58  // RegisterLookup registers a method as a lookup for tracers, meaning that
    59  // users can invoke a named tracer through that lookup. If 'wildcard' is true,
    60  // then the lookup will be placed last. This is typically meant for interpreted
    61  // engines (js) which can evaluate dynamic user-supplied code.
    62  func RegisterLookup(wildcard bool, lookup lookupFunc) {
    63  	if wildcard {
    64  		lookups = append(lookups, lookup)
    65  	} else {
    66  		lookups = append([]lookupFunc{lookup}, lookups...)
    67  	}
    68  }
    69  
    70  // New returns a new instance of a tracer, by iterating through the
    71  // registered lookups.
    72  func New(code string, ctx *Context) (Tracer, error) {
    73  	for _, lookup := range lookups {
    74  		if tracer, err := lookup(code, ctx); err == nil {
    75  			return tracer, nil
    76  		}
    77  	}
    78  	return nil, errors.New("tracer not found")
    79  }