github.1485827954.workers.dev/ethereum/go-ethereum@v1.14.3/eth/tracers/dir.go (about)

     1  // Copyright 2017 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum 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 go-ethereum 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 go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package tracers
    18  
    19  import (
    20  	"encoding/json"
    21  	"math/big"
    22  
    23  	"github.com/ethereum/go-ethereum/common"
    24  	"github.com/ethereum/go-ethereum/core/tracing"
    25  )
    26  
    27  // Context contains some contextual infos for a transaction execution that is not
    28  // available from within the EVM object.
    29  type Context struct {
    30  	BlockHash   common.Hash // Hash of the block the tx is contained within (zero if dangling tx or call)
    31  	BlockNumber *big.Int    // Number of the block the tx is contained within (zero if dangling tx or call)
    32  	TxIndex     int         // Index of the transaction within a block (zero if dangling tx or call)
    33  	TxHash      common.Hash // Hash of the transaction being traced (zero if dangling call)
    34  }
    35  
    36  // The set of methods that must be exposed by a tracer
    37  // for it to be available through the RPC interface.
    38  // This involves a method to retrieve results and one to
    39  // stop tracing.
    40  type Tracer struct {
    41  	*tracing.Hooks
    42  	GetResult func() (json.RawMessage, error)
    43  	// Stop terminates execution of the tracer at the first opportune moment.
    44  	Stop func(err error)
    45  }
    46  
    47  type ctorFn func(*Context, json.RawMessage) (*Tracer, error)
    48  type jsCtorFn func(string, *Context, json.RawMessage) (*Tracer, error)
    49  
    50  type elem struct {
    51  	ctor ctorFn
    52  	isJS bool
    53  }
    54  
    55  // DefaultDirectory is the collection of tracers bundled by default.
    56  var DefaultDirectory = directory{elems: make(map[string]elem)}
    57  
    58  // directory provides functionality to lookup a tracer by name
    59  // and a function to instantiate it. It falls back to a JS code evaluator
    60  // if no tracer of the given name exists.
    61  type directory struct {
    62  	elems  map[string]elem
    63  	jsEval jsCtorFn
    64  }
    65  
    66  // Register registers a method as a lookup for tracers, meaning that
    67  // users can invoke a named tracer through that lookup.
    68  func (d *directory) Register(name string, f ctorFn, isJS bool) {
    69  	d.elems[name] = elem{ctor: f, isJS: isJS}
    70  }
    71  
    72  // RegisterJSEval registers a tracer that is able to parse
    73  // dynamic user-provided JS code.
    74  func (d *directory) RegisterJSEval(f jsCtorFn) {
    75  	d.jsEval = f
    76  }
    77  
    78  // New returns a new instance of a tracer, by iterating through the
    79  // registered lookups. Name is either name of an existing tracer
    80  // or an arbitrary JS code.
    81  func (d *directory) New(name string, ctx *Context, cfg json.RawMessage) (*Tracer, error) {
    82  	if elem, ok := d.elems[name]; ok {
    83  		return elem.ctor(ctx, cfg)
    84  	}
    85  	// Assume JS code
    86  	return d.jsEval(name, ctx, cfg)
    87  }
    88  
    89  // IsJS will return true if the given tracer will evaluate
    90  // JS code. Because code evaluation has high overhead, this
    91  // info will be used in determining fast and slow code paths.
    92  func (d *directory) IsJS(name string) bool {
    93  	if elem, ok := d.elems[name]; ok {
    94  		return elem.isJS
    95  	}
    96  	// JS eval will execute JS code
    97  	return true
    98  }