path: root/jsre/pretty.go

// Copyright 2015 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 jsre

import (
    "fmt"
    "sort"
    "strconv"
    "strings"

    "github.com/fatih/color"
    "github.com/robertkrimen/otto"
)

const (
    maxPrettyPrintLevel = 3
    indentString        = "  "
)

var (
    functionColor = color.New(color.FgMagenta)
    specialColor  = color.New(color.Bold)
    numberColor   = color.New(color.FgRed)
    stringColor   = color.New(color.FgGreen)
)

// these fields are hidden when printing objects.
var boringKeys = map[string]bool{
    "valueOf":              true,
    "toString":             true,
    "toLocaleString":       true,
    "hasOwnProperty":       true,
    "isPrototypeOf":        true,
    "propertyIsEnumerable": true,
    "constructor":          true,
}

// prettyPrint writes value to standard output.
func prettyPrint(vm *otto.Otto, value otto.Value) {
    ppctx{vm}.printValue(value, 0, false)
}

func prettyPrintJS(call otto.FunctionCall) otto.Value {
    for _, v := range call.ArgumentList {
        prettyPrint(call.Otto, v)
        fmt.Println()
    }
    return otto.UndefinedValue()
}

type ppctx struct{ vm *otto.Otto }

func (ctx ppctx) indent(level int) string {
    return strings.Repeat(indentString, level)
}

func (ctx ppctx) printValue(v otto.Value, level int, inArray bool) {
    switch {
    case v.IsObject():
        ctx.printObject(v.Object(), level, inArray)
    case v.IsNull():
        specialColor.Print("null")
    case v.IsUndefined():
        specialColor.Print("undefined")
    case v.IsString():
        s, _ := v.ToString()
        stringColor.Printf("%q", s)
    case v.IsBoolean():
        b, _ := v.ToBoolean()
        specialColor.Printf("%t", b)
    case v.IsNaN():
        numberColor.Printf("NaN")
    case v.IsNumber():
        s, _ := v.ToString()
        numberColor.Printf("%s", s)
    default:
        fmt.Printf("<unprintable>")
    }
}

func (ctx ppctx) printObject(obj *otto.Object, level int, inArray bool) {
    switch obj.Class() {
    case "Array":
        lv, _ := obj.Get("length")
        len, _ := lv.ToInteger()
        if len == 0 {
            fmt.Printf("[]")
            return
        }
        if level > maxPrettyPrintLevel {
            fmt.Print("[...]")
            return
        }
        fmt.Print("[")
        for i := int64(0); i < len; i++ {
            el, err := obj.Get(strconv.FormatInt(i, 10))
            if err == nil {
                ctx.printValue(el, level+1, true)
            }
            if i < len-1 {
                fmt.Printf(", ")
            }
        }
        fmt.Print("]")

    case "Object":
        // Print values from bignumber.js as regular numbers.
        if ctx.isBigNumber(obj) {
            numberColor.Print(toString(obj))
            return
        }
        // Otherwise, print all fields indented, but stop if we're too deep.
        keys := ctx.fields(obj)
        if len(keys) == 0 {
            fmt.Print("{}")
            return
        }
        if level > maxPrettyPrintLevel {
            fmt.Print("{...}")
            return
        }
        fmt.Println("{")
        for i, k := range keys {
            v, _ := obj.Get(k)
            fmt.Printf("%s%s: ", ctx.indent(level+1), k)
            ctx.printValue(v, level+1, false)
            if i < len(keys)-1 {
                fmt.Printf(",")
            }
            fmt.Println()
        }
        if inArray {
            level--
        }
        fmt.Printf("%s}", ctx.indent(level))

    case "Function":
        // Use toString() to display the argument list if possible.
        if robj, err := obj.Call("toString"); err != nil {
            functionColor.Print("function()")
        } else {
            desc := strings.Trim(strings.Split(robj.String(), "{")[0], " \t\n")
            desc = strings.Replace(desc, " (", "(", 1)
            functionColor.Print(desc)
        }

    case "RegExp":
        stringColor.Print(toString(obj))

    default:
        if v, _ := obj.Get("toString"); v.IsFunction() && level <= maxPrettyPrintLevel {
            s, _ := obj.Call("toString")
            fmt.Printf("<%s %s>", obj.Class(), s.String())
        } else {
            fmt.Printf("<%s>", obj.Class())
        }
    }
}

func (ctx ppctx) fields(obj *otto.Object) []string {
    var (
        vals, methods []string
        seen          = make(map[string]bool)
    )
    add := func(k string) {
        if seen[k] || boringKeys[k] || strings.HasPrefix(k, "_") {
            return
        }
        seen[k] = true
        if v, _ := obj.Get(k); v.IsFunction() {
            methods = append(methods, k)
        } else {
            vals = append(vals, k)
        }
    }
    iterOwnAndConstructorKeys(ctx.vm, obj, add)
    sort.Strings(vals)
    sort.Strings(methods)
    return append(vals, methods...)
}

func iterOwnAndConstructorKeys(vm *otto.Otto, obj *otto.Object, f func(string)) {
    seen := make(map[string]bool)
    iterOwnKeys(vm, obj, func(prop string) {
        seen[prop] = true
        f(prop)
    })
    if cp := constructorPrototype(obj); cp != nil {
        iterOwnKeys(vm, cp, func(prop string) {
            if !seen[prop] {
                f(prop)
            }
        })
    }
}

func iterOwnKeys(vm *otto.Otto, obj *otto.Object, f func(string)) {
    Object, _ := vm.Object("Object")
    rv, _ := Object.Call("getOwnPropertyNames", obj.Value())
    gv, _ := rv.Export()
    switch gv := gv.(type) {
    case []interface{}:
        for _, v := range gv {
            f(v.(string))
        }
    case []string:
        for _, v := range gv {
            f(v)
        }
    default:
        panic(fmt.Errorf("Object.getOwnPropertyNames returned unexpected type %T", gv))
    }
}

func (ctx ppctx) isBigNumber(v *otto.Object) bool {
    // Handle numbers with custom constructor.
    if v, _ := v.Get("constructor"); v.Object() != nil {
        if strings.HasPrefix(toString(v.Object()), "function BigNumber") {
            return true
        }
    }
    // Handle default constructor.
    BigNumber, _ := ctx.vm.Object("BigNumber.prototype")
    if BigNumber == nil {
        return false
    }
    bv, _ := BigNumber.Call("isPrototypeOf", v)
    b, _ := bv.ToBoolean()
    return b
}

func toString(obj *otto.Object) string {
    s, _ := obj.Call("toString")
    return s.String()
}

func constructorPrototype(obj *otto.Object) *otto.Object {
    if v, _ := obj.Get("constructor"); v.Object() != nil {
        if v, _ = v.Object().Get("prototype"); v.Object() != nil {
            return v.Object()
        }
    }
    return nil
}