cmd, core, eth/tracers: support fancier js tracing (#15516)

* cmd, core, eth/tracers: support fancier js tracing

* eth, internal/web3ext: rework trace API, concurrency, chain tracing

* eth/tracers: add three more JavaScript tracers

* eth/tracers, vendor: swap ottovm to duktape for tracing

* core, eth, internal: finalize call tracer and needed extras

* eth, tests: prestate tracer, call test suite, rewinding

* vendor: fix windows builds for tracer js engine

* vendor: temporary duktape fix

* eth/tracers: fix up 4byte and evmdis tracer

* vendor: pull in latest duktape with my upstream fixes

* eth: fix some review comments

* eth: rename rewind to reexec to make it more obvious

* core/vm: terminate tracing using defers

1 files changed, 53 insertions, 0 deletions

diff --git a/eth/tracers/tracers.go b/eth/tracers/tracers.go
new file mode 100644
index 000000000..4e1ef23ad
--- /dev/null
+++ b/eth/tracers/tracers.go
@@ -0,0 +1,53 @@
+// Copyright 2017 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// Package tracers is a collection of JavaScript transaction tracers.
+package tracers
+
+import (
+	"strings"
+	"unicode"
+
+	"github.com/ethereum/go-ethereum/eth/tracers/internal/tracers"
+)
+
+// all contains all the built in JavaScript tracers by name.
+var all = make(map[string]string)
+
+// camel converts a snake cased input string into a camel cased output.
+func camel(str string) string {
+	pieces := strings.Split(str, "_")
+	for i := 1; i < len(pieces); i++ {
+		pieces[i] = string(unicode.ToUpper(rune(pieces[i][0]))) + pieces[i][1:]
+	}
+	return strings.Join(pieces, "")
+}
+
+// init retrieves the JavaScript transaction tracers included in go-ethereum.
+func init() {
+	for _, file := range tracers.AssetNames() {
+		name := camel(strings.TrimSuffix(file, ".js"))
+		all[name] = string(tracers.MustAsset(file))
+	}
+}
+
+// tracer retrieves a specific JavaScript tracer by name.
+func tracer(name string) (string, bool) {
+	if tracer, ok := all[name]; ok {
+		return tracer, true
+	}
+	return "", false
+}