added lua interpreter support for custom math functions

go/calc.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 
 	"github.com/chzyer/readline"
+	lua "github.com/yuin/gopher-lua"
 )
 
 type Calc struct {
@@ -17,6 +18,7 @@ type Calc struct {
 	stack     *Stack
 	history   []string
 	completer readline.AutoCompleter
+	L         *lua.LState
 }
 
 const Help string = `Available commands:
@@ -34,10 +36,24 @@ basic operators: + - * /
 Math operators:
 ^       power`
 
+// That way I can add custom functions to completion
+func GetCompleteCustomFunctions() func(string) []string {
+	return func(line string) []string {
+		funcs := []string{}
+		for luafunc := range LuaFuncs {
+			funcs = append(funcs, luafunc)
+		}
+		return funcs
+	}
+}
+
 func NewCalc() *Calc {
 	c := Calc{stack: NewStack(), debug: false}
 
 	c.completer = readline.NewPrefixCompleter(
+		// custom lua functions
+		readline.PcItemDynamic(GetCompleteCustomFunctions()),
+
 		// commands
 		readline.PcItem("dump"),
 		readline.PcItem("reverse"),
@@ -102,11 +118,16 @@ func (c *Calc) Eval(line string) {
 		"SqrtPhi", "Ln2", "Log2E", "Ln10", "Log10E"}
 	functions := []string{"sqrt", "remainder", "%", "%-", "%+"}
 	batch := []string{"median", "avg"}
+	luafuncs := []string{}
 
 	if line == "" {
 		return
 	}
 
+	for luafunc := range LuaFuncs {
+		luafuncs = append(luafuncs, luafunc)
+	}
+
 	for _, item := range space.Split(line, -1) {
 		num, err := strconv.ParseFloat(item, 64)
 
@@ -135,6 +156,11 @@ func (c *Calc) Eval(line string) {
 				continue
 			}
 
+			if contains(luafuncs, item) {
+				c.luafunc(item)
+				continue
+			}
+
 			switch item {
 			case "help":
 				fmt.Println(Help)
@@ -333,38 +359,22 @@ func (c *Calc) batchfunc(funcname string) {
 	_ = c.Result()
 }
 
-func contains(s []string, e string) bool {
-	for _, a := range s {
-		if a == e {
-			return true
-		}
-	}
-	return false
-}
+func (c *Calc) luafunc(funcname string) {
+	// we may need to put them onto the stack afterwards!
+	c.stack.Backup()
+	b := c.stack.Pop()
+	a := c.stack.Pop()
 
-func const2num(name string) float64 {
-	switch name {
-	case "Pi":
-		return math.Pi
-	case "Phi":
-		return math.Phi
-	case "Sqrt2":
-		return math.Sqrt2
-	case "SqrtE":
-		return math.SqrtE
-	case "SqrtPi":
-		return math.SqrtPi
-	case "SqrtPhi":
-		return math.SqrtPhi
-	case "Ln2":
-		return math.Ln2
-	case "Log2E":
-		return math.Log2E
-	case "Ln10":
-		return math.Ln10
-	case "Log10E":
-		return math.Log10E
-	default:
-		return 0
+	x, err := CallLuaFunc(c.L, funcname, a, b)
+	if err != nil {
+		fmt.Println(err)
+		c.stack.Push(a)
+		c.stack.Push(b)
+		return
 	}
+
+	c.History("%s(%f,%f) = %f", funcname, a, b, x)
+	c.stack.Push(x)
+
+	c.Result()
 }

go/go.mod

@@ -5,5 +5,6 @@ go 1.20
 require (
 	github.com/chzyer/readline v1.5.1 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
+	github.com/yuin/gopher-lua v1.1.0 // indirect
 	golang.org/x/sys v0.0.0-20220310020820-b874c991c1a5 // indirect
 )

go/go.sum

@@ -4,5 +4,7 @@ github.com/chzyer/readline v1.5.1/go.mod h1:Eh+b79XXUwfKfcPLepksvw2tcLE/Ct21YObk
 github.com/chzyer/test v1.0.0/go.mod h1:2JlltgoNkt4TW/z9V/IzDdFaMTM2JPIi26O1pF38GC8=
 github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
 github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+github.com/yuin/gopher-lua v1.1.0 h1:BojcDhfyDWgU2f2TOzYK/g5p2gxMrku8oupLDqlnSqE=
+github.com/yuin/gopher-lua v1.1.0/go.mod h1:GBR0iDaNXjAgGg9zfCvksxSRnQx76gclCIb7kdAd1Pw=
 golang.org/x/sys v0.0.0-20220310020820-b874c991c1a5 h1:y/woIyUBFbpQGKS0u1aHF/40WUDnek3fPOyD08H5Vng=
 golang.org/x/sys v0.0.0-20220310020820-b874c991c1a5/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

go/interpreter.go

@@ -0,0 +1,72 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+
+	lua "github.com/yuin/gopher-lua"
+)
+
+// LUA interpreter, instanciated in main()
+var L *lua.LState
+
+var LuaFuncs map[string]int
+
+// called from lua to register a 1 arg math function
+func RegisterFuncOneArg(L *lua.LState) int {
+	function := L.ToString(1)
+	LuaFuncs[function] = 1
+	return 1
+}
+
+// called from lua to register a 1 arg math function
+func RegisterFuncTwoArg(L *lua.LState) int {
+	function := L.ToString(1)
+	LuaFuncs[function] = 2
+	return 1
+}
+
+func InitLua(L *lua.LState) {
+	LuaFuncs = map[string]int{}
+	L.SetGlobal("RegisterFuncOneArg", L.NewFunction(RegisterFuncOneArg))
+	L.SetGlobal("RegisterFuncTwoArg", L.NewFunction(RegisterFuncTwoArg))
+
+	if err := L.CallByParam(lua.P{
+		Fn:      L.GetGlobal("init"),
+		NRet:    0,
+		Protect: true,
+	}); err != nil {
+		panic(err)
+	}
+}
+
+func CallLuaFunc(L *lua.LState, funcname string, a float64, b float64) (float64, error) {
+	if LuaFuncs[funcname] == 1 {
+		// 1 arg variant
+		if err := L.CallByParam(lua.P{
+			Fn:      L.GetGlobal(funcname),
+			NRet:    1,
+			Protect: true,
+		}, lua.LNumber(a)); err != nil {
+			fmt.Println(err)
+			return 0, err
+		}
+	} else {
+		// 2 arg variant
+		if err := L.CallByParam(lua.P{
+			Fn:      L.GetGlobal(funcname),
+			NRet:    1,
+			Protect: true,
+		}, lua.LNumber(a), lua.LNumber(b)); err != nil {
+			return 0, err
+		}
+	}
+
+	// get result and cast to float64
+	if res, ok := L.Get(-1).(lua.LNumber); ok {
+		L.Pop(1)
+		return float64(res), nil
+	}
+
+	return 0, errors.New("function did not return a float64!")
+}

go/main.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/chzyer/readline"
 	flag "github.com/spf13/pflag"
+	lua "github.com/yuin/gopher-lua"
 )
 
 const VERSION string = "0.0.1"
@@ -23,8 +24,7 @@ Options:
 When <operator>  is given, batch  mode ist automatically  enabled. Use
 this only when working with stdin. E.g.: echo "2 3 4 5" | rpn +
 
-Copyright (c) 2023 T.v.Dein
-`
+Copyright (c) 2023 T.v.Dein`
 
 func main() {
 	calc := NewCalc()
@@ -32,11 +32,14 @@ func main() {
 	showversion := false
 	showhelp := false
 	enabledebug := false
+	configfile := ""
 
 	flag.BoolVarP(&calc.batch, "batchmode", "b", false, "batch mode")
 	flag.BoolVarP(&enabledebug, "debug", "d", false, "debug mode")
 	flag.BoolVarP(&showversion, "version", "v", false, "show version")
 	flag.BoolVarP(&showhelp, "help", "h", false, "show usage")
+	flag.StringVarP(&configfile, "config", "c", os.Getenv("HOME")+"/.rpn.lua", "config file (lua format)")
+
 	flag.Parse()
 
 	if showversion {
@@ -53,6 +56,18 @@ func main() {
 		calc.ToggleDebug()
 	}
 
+	if _, err := os.Stat(configfile); err == nil {
+		L = lua.NewState()
+		defer L.Close()
+
+		if err := L.DoFile(configfile); err != nil {
+			panic(err)
+		}
+
+		InitLua(L)
+		calc.L = L
+	}
+
 	rl, err := readline.NewEx(&readline.Config{
 		Prompt:            "\033[31m»\033[0m ",
 		HistoryFile:       os.Getenv("HOME") + "/.rpn-history",

go/test.lua

@@ -0,0 +1,12 @@
+function add(a,b)
+  return a + b
+end
+
+function parallelresistance(a,b)
+  return 1.0 / (a * b)
+end
+
+function init()
+  RegisterFuncTwoArg("add")
+  RegisterFuncTwoArg("parallelresistance")
+end  

go/util.go

@@ -0,0 +1,39 @@
+package main
+
+import "math"
+
+func contains(s []string, e string) bool {
+	for _, a := range s {
+		if a == e {
+			return true
+		}
+	}
+	return false
+}
+
+func const2num(name string) float64 {
+	switch name {
+	case "Pi":
+		return math.Pi
+	case "Phi":
+		return math.Phi
+	case "Sqrt2":
+		return math.Sqrt2
+	case "SqrtE":
+		return math.SqrtE
+	case "SqrtPi":
+		return math.SqrtPi
+	case "SqrtPhi":
+		return math.SqrtPhi
+	case "Ln2":
+		return math.Ln2
+	case "Log2E":
+		return math.Log2E
+	case "Ln10":
+		return math.Ln10
+	case "Log10E":
+		return math.Log10E
+	default:
+		return 0
+	}
+}