bump version

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v2...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/ISSUE_TEMPLATE/bug_report.md

@@ -7,7 +7,7 @@ assignees: TLINDEN
 
 ---
 
-**Describtion**
+**Description**
 <!-- Please provide a clear and concise description of the issue: -->
 
 

.github/dependabot.yml

@@ -0,0 +1,10 @@
+version: 2
+updates:
+  - package-ecosystem: "gomod"
+    directory: "/"
+    schedule:
+      interval: "monthly"
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+        interval: "monthly"

.github/workflows/ci.yaml

@@ -4,22 +4,22 @@ jobs:
   build:
     strategy:
       matrix:
-        version: [1.21]
+        version: [1.22.1]
         os: [ubuntu-latest, windows-latest, macos-latest]
     name: Build
     runs-on: ${{ matrix.os }}
     steps:
-    - name: Set up Go
+    - name: Set up Go ${{ matrix.version }}
-      uses: actions/setup-go@v3
+      uses: actions/setup-go@v5
       with:
-        go-version: ${{ matrix.version }}
+        go-version: '${{ matrix.version }}'
       id: go
 
     - name: checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: build
-      run: go build
+      run: make buildlocal
 
     - name: test
       run: make test
@@ -28,9 +28,11 @@ jobs:
     name: lint
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/setup-go@v3
+      - uses: actions/setup-go@v5
         with:
-          go-version: 1.21
+          go-version: 1.22
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: golangci-lint
-        uses: golangci/golangci-lint-action@v3
+        uses: golangci/golangci-lint-action@v6
+        with:
+          skip-cache: true

.github/workflows/release.yaml

@@ -0,0 +1,32 @@
+name: build-and-test
+on:
+  push:
+    tags:
+      - "*"
+
+jobs:
+  release:
+    name: Build Release Assets
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: 1.22.11
+
+      - name: Build the executables
+        run: ./mkrel.sh rpnc ${{ github.ref_name}}
+
+      - name: List the executables
+        run: ls -l ./releases
+
+      - name: Upload the binaries
+        uses: svenstaro/upload-release-action@v2
+        with:
+          repo_token: ${{ secrets.GITHUB_TOKEN }}
+          tag: ${{ github.ref_name }}
+          file: ./releases/*
+          file_glob: true

Makefile

@@ -51,14 +51,25 @@ install: buildlocal
 	install -o $(UID) -g $(GID) -m 444 $(tool).1 $(PREFIX)/man/man1/
 
 clean:
-	rm -rf $(tool) coverage.out
+	rm -rf $(tool) coverage.out testdata
 
-test:
+test: clean
-	go test -v ./...
+	go test ./... $(ARGS)
+
+testfuzzy: clean
+	go test -fuzz ./... $(ARGS)
+
+testlint: test lint
+
+lint:
+	golangci-lint run
+
+lint-full:
+	golangci-lint run --enable-all --exclude-use-default --disable exhaustivestruct,exhaustruct,depguard,interfacer,deadcode,golint,structcheck,scopelint,varcheck,ifshort,maligned,nosnakecase,godot,funlen,gofumpt,cyclop,noctx,gochecknoglobals,paralleltest,forbidigo,godox,dupword,forcetypeassert,goerr113,gomnd
 
 singletest:
-	@echo "Call like this: ''make singletest TEST=TestPrepareColumns"
+	@echo "Call like this: make singletest TEST=TestPrepareColumns ARGS=-v"
-	go test -run $(TEST)
+	go test -run $(TEST) $(ARGS)
 
 cover-report:
 	go test ./... -cover -coverprofile=coverage.out
@@ -70,8 +81,8 @@ goupdate:
 buildall:
 	./mkrel.sh $(tool) $(VERSION)
 
-release: buildall
+release:
-	gh release create v$(VERSION) --generate-notes releases/*
+	gh release create v$(VERSION) --generate-notes
 
 show-versions: buildlocal
 	@echo "### rpn version:"

calc.go

@@ -1,5 +1,5 @@
 /*
-Copyright © 2023 Thomas von Dein
+Copyright © 2023-2024 Thomas von Dein
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -20,8 +20,9 @@ package main
 import (
 	"errors"
 	"fmt"
-	"os"
+	"math"
 	"regexp"
+	"sort"
 	"strconv"
 	"strings"
 
@@ -35,6 +36,8 @@ type Calc struct {
 	showstack    bool
 	intermediate bool
 	notdone      bool // set to true as long as there are items left in the eval loop
+	precision    int
+
 	stack        *Stack
 	history      []string
 	completer    readline.AutoCompleter
@@ -48,30 +51,25 @@ type Calc struct {
 	Funcalls      Funcalls
 	BatchFuncalls Funcalls
 
+	// different kinds of commands, displays nicer in help output
+	StackCommands    Commands
+	SettingsCommands Commands
+	ShowCommands     Commands
+	Commands         Commands
+
 	Vars map[string]float64
 }
 
 // help for lua functions will be added dynamically
-const Help string = `Available commands:
+const Help string = `
-batch                toggle batch mode
-debug                toggle debug output
-show                 show the last 5 items of the stack
-dump                 display the stack contents
-clear                clear the whole stack
-shift                remove the last element of the stack
-reverse              reverse the stack elements
-swap                 exchange the last two elements
-vars                 show list of variables
-history              display calculation history
-help|?               show this message
-quit|exit|c-d|c-c    exit program
-
 Operators:
 basic operators: + - x * / ^  (* is an alias of x)
 
+Bitwise operators: and or xor < (left shift) > (right shift)
+
 Percent functions:
 %                    percent
-%-                   substract percent
+%-                   subtract percent
 %+                   add percent
 
 Math functions (see https://pkg.go.dev/math):
@@ -94,8 +92,9 @@ Register variables:
 // commands, constants and operators,  defined here to feed completion
 // and our mode switch in Eval() dynamically
 const (
-	Commands  string = `dump reverse debug undebug clear batch shift undo help history manual exit quit swap show vars`
 	Constants    string = `Pi Phi Sqrt2 SqrtE SqrtPi SqrtPhi Ln2 Log2E Ln10 Log10E`
+	Precision    int    = 2
+	ShowStackLen int    = 5
 )
 
 // That way we can add custom functions to completion
@@ -107,7 +106,6 @@ func GetCompleteCustomFunctions() func(string) []string {
 			completions = append(completions, luafunc)
 		}
 
-		completions = append(completions, strings.Split(Commands, " ")...)
 		completions = append(completions, strings.Split(Constants, " ")...)
 
 		return completions
@@ -126,37 +124,62 @@ func (c *Calc) GetCompleteCustomFuncalls() func(string) []string {
 			completions = append(completions, function)
 		}
 
-		return completions
+		for command := range c.SettingsCommands {
+			if len(command) > 1 {
+				completions = append(completions, command)
+			}
 		}
 
+		for command := range c.ShowCommands {
+			if len(command) > 1 {
+				completions = append(completions, command)
+			}
+		}
+
+		for command := range c.StackCommands {
+			if len(command) > 1 {
+				completions = append(completions, command)
+			}
+		}
+
+		for command := range c.Commands {
+			if len(command) > 1 {
+				completions = append(completions, command)
+			}
+		}
+
+		return completions
+	}
 }
 
 func NewCalc() *Calc {
-	c := Calc{stack: NewStack(), debug: false}
+	calc := Calc{stack: NewStack(), debug: false, precision: Precision}
 
-	c.Funcalls = DefineFunctions()
+	calc.Funcalls = DefineFunctions()
-	c.BatchFuncalls = DefineBatchFunctions()
+	calc.BatchFuncalls = DefineBatchFunctions()
-	c.Vars = map[string]float64{}
+	calc.Vars = map[string]float64{}
 
-	c.completer = readline.NewPrefixCompleter(
+	calc.completer = readline.NewPrefixCompleter(
 		// custom lua functions
 		readline.PcItemDynamic(GetCompleteCustomFunctions()),
-		readline.PcItemDynamic(c.GetCompleteCustomFuncalls()),
+		readline.PcItemDynamic(calc.GetCompleteCustomFuncalls()),
 	)
 
-	c.Space = regexp.MustCompile(`\s+`)
+	calc.Space = regexp.MustCompile(`\s+`)
-	c.Comment = regexp.MustCompile(`#.*`) // ignore everything after #
+	calc.Comment = regexp.MustCompile(`#.*`) // ignore everything after #
-	c.Register = regexp.MustCompile(`^([<>])([A-Z][A-Z0-9]*)`)
+	calc.Register = regexp.MustCompile(`^([<>])([A-Z][A-Z0-9]*)`)
 
 	// pre-calculate mode switching arrays
-	c.Constants = strings.Split(Constants, " ")
+	calc.Constants = strings.Split(Constants, " ")
 
-	return &c
+	calc.SetCommands()
+
+	return &calc
 }
 
 // setup the interpreter, called from main(), import lua functions
-func (c *Calc) SetInt(I *Interpreter) {
+func (c *Calc) SetInt(interpreter *Interpreter) {
-	c.interpreter = I
+	c.interpreter = interpreter
 
 	for name := range LuaFuncs {
 		c.LuaFunctions = append(c.LuaFunctions, name)
@@ -183,31 +206,31 @@ func (c *Calc) ToggleShow() {
 }
 
 func (c *Calc) Prompt() string {
-	p := "\033[31m»\033[0m "
+	prompt := "\033[31m»\033[0m "
-	b := ""
+	batch := ""
 
 	if c.batch {
-		b = "->batch"
+		batch = "->batch"
 	}
 
-	d := ""
+	debug := ""
-	v := ""
+	revision := ""
 
 	if c.debug {
-		d = "->debug"
+		debug = "->debug"
-		v = fmt.Sprintf("/rev%d", c.stack.rev)
+		revision = fmt.Sprintf("/rev%d", c.stack.rev)
 	}
 
-	return fmt.Sprintf("rpn%s%s [%d%s]%s", b, d, c.stack.Len(), v, p)
+	return fmt.Sprintf("rpn%s%s [%d%s]%s", batch, debug, c.stack.Len(), revision, prompt)
 }
 
 // the actual work horse, evaluate a line of calc command[s]
-func (c *Calc) Eval(line string) {
+func (c *Calc) Eval(line string) error {
 	// remove surrounding whitespace and comments, if any
 	line = strings.TrimSpace(c.Comment.ReplaceAllString(line, ""))
 
 	if line == "" {
-		return
+		return nil
 	}
 
 	items := c.Space.Split(line, -1)
@@ -219,48 +242,93 @@ func (c *Calc) Eval(line string) {
 			c.notdone = false
 		}
 
+		if err := c.EvalItem(item); err != nil {
+			return err
+		}
+	}
+
+	if c.showstack && !c.stdin {
+		dots := ""
+
+		if c.stack.Len() > ShowStackLen {
+			dots = "... "
+		}
+
+		last := c.stack.Last(ShowStackLen)
+
+		fmt.Printf("stack: %s%s\n", dots, list2str(last))
+	}
+
+	return nil
+}
+
+func (c *Calc) EvalItem(item string) error {
 	num, err := strconv.ParseFloat(item, 64)
 
 	if err == nil {
 		c.stack.Backup()
 		c.stack.Push(num)
-		} else {
+
+		return nil
+	}
+
+	// try time
+	var hour, min int
+	_, err = fmt.Sscanf(item, "%d:%d", &hour, &min)
+	if err == nil {
+		c.stack.Backup()
+		c.stack.Push(float64(hour) + float64(min)/60)
+
+		return nil
+	}
+
+	// try hex
+	var i int
+	_, err = fmt.Sscanf(item, "0x%x", &i)
+	if err == nil {
+		c.stack.Backup()
+		c.stack.Push(float64(i))
+
+		return nil
+	}
+
 	if contains(c.Constants, item) {
 		// put the constant onto the stack
 		c.stack.Backup()
 		c.stack.Push(const2num(item))
-				continue
+
+		return nil
 	}
 
-			if _, ok := c.Funcalls[item]; ok {
+	if exists(c.Funcalls, item) {
 		if err := c.DoFuncall(item); err != nil {
-					fmt.Println(err)
+			return Error(err.Error())
-				} else {
-					c.Result()
-				}
-				continue
 		}
 
-			if c.batch {
-				if _, ok := c.BatchFuncalls[item]; ok {
-					if err := c.DoFuncall(item); err != nil {
-						fmt.Println(err)
-					} else {
 		c.Result()
+
+		return nil
 	}
-					continue
+
+	if exists(c.BatchFuncalls, item) {
+		if !c.batch {
+			return Error("only supported in batch mode")
 		}
-			} else {
+
-				if _, ok := c.BatchFuncalls[item]; ok {
+		if err := c.DoFuncall(item); err != nil {
-					fmt.Println("only supported in batch mode")
+			return Error(err.Error())
-					continue
 		}
+
+		c.Result()
+
+		return nil
 	}
 
 	if contains(c.LuaFunctions, item) {
 		// user provided custom lua functions
 		c.EvalLuaFunction(item)
-				continue
+
+		return nil
 	}
 
 	regmatches := c.Register.FindStringSubmatch(item)
@@ -271,84 +339,45 @@ func (c *Calc) Eval(line string) {
 		case "<":
 			c.GetVar(regmatches[2])
 		}
-				continue
+
+		return nil
+	}
+
+	// internal commands
+	// FIXME: propagate errors
+	if exists(c.Commands, item) {
+		c.Commands[item].Func(c)
+
+		return nil
+	}
+
+	if exists(c.ShowCommands, item) {
+		c.ShowCommands[item].Func(c)
+
+		return nil
+	}
+
+	if exists(c.StackCommands, item) {
+		c.StackCommands[item].Func(c)
+
+		return nil
+	}
+
+	if exists(c.SettingsCommands, item) {
+		c.SettingsCommands[item].Func(c)
+
+		return nil
 	}
 
-			// management commands
 	switch item {
-			case "?":
+	case "?", "help":
-				fallthrough
+		c.PrintHelp()
-			case "help":
-				fmt.Println(Help)
-				if len(LuaFuncs) > 0 {
-					fmt.Println("Lua functions:")
-					for name, function := range LuaFuncs {
-						fmt.Printf("%-20s %s\n", name, function.help)
-					}
-				}
-			case "dump":
-				c.stack.Dump()
-			case "debug":
-				c.ToggleDebug()
-			case "undebug":
-				c.debug = false
-			case "batch":
-				c.ToggleBatch()
-			case "clear":
-				c.stack.Backup()
-				c.stack.Clear()
-			case "shift":
-				c.stack.Backup()
-				c.stack.Shift()
-			case "reverse":
-				c.stack.Backup()
-				c.stack.Reverse()
-			case "swap":
-				if c.stack.Len() < 2 {
-					fmt.Println("stack too small, can't swap")
-				} else {
-					c.stack.Backup()
-					c.stack.Swap()
-				}
-			case "undo":
-				c.stack.Restore()
-			case "history":
-				for _, entry := range c.history {
-					fmt.Println(entry)
-				}
-			case "show":
-				c.ToggleShow()
-			case "exit":
-				fallthrough
-			case "quit":
-				os.Exit(0)
-			case "manual":
-				man()
-			case "vars":
-				if len(c.Vars) > 0 {
-					fmt.Printf("%-20s     %s\n", "VARIABLE", "VALUE")
-					for k, v := range c.Vars {
-						fmt.Printf("%-20s  -> %.2f\n", k, v)
-					}
-				} else {
-					fmt.Println("no vars registered")
-				}
 
 	default:
-				fmt.Println("unknown command or operator!")
+		return Error("unknown command or operator")
-			}
-		}
 	}
 
-	if c.showstack && !c.stdin {
+	return nil
-		dots := ""
-
-		if c.stack.Len() > 5 {
-			dots = "... "
-		}
-		last := c.stack.Last(5)
-		fmt.Printf("stack: %s%s\n", dots, list2str(last))
-	}
 }
 
 // Execute a math function, check if it is defined just in case
@@ -361,10 +390,11 @@ func (c *Calc) DoFuncall(funcname string) error {
 	}
 
 	if function == nil {
-		panic("function not defined but in completion list")
+		return Error("function not defined but in completion list")
 	}
 
 	var args Numbers
+
 	batch := false
 
 	if function.Expectargs == -1 {
@@ -386,11 +416,11 @@ func (c *Calc) DoFuncall(funcname string) error {
 	// the  actual lambda call, so  to say. We provide  a slice of
 	// the requested size, fetched  from the stack (but not popped
 	// yet!)
-	R := function.Func(args)
+	funcresult := function.Func(args)
 
-	if R.Err != nil {
+	if funcresult.Err != nil {
 		// leave the stack untouched in case of any error
-		return R.Err
+		return funcresult.Err
 	}
 
 	// don't forget to backup!
@@ -406,10 +436,11 @@ func (c *Calc) DoFuncall(funcname string) error {
 	}
 
 	// save result
-	c.stack.Push(R.Res)
+	c.stack.Push(funcresult.Res)
 
 	// thanks a lot
-	c.SetHistory(funcname, args, R.Res)
+	c.SetHistory(funcname, args, funcresult.Res)
+
 	return nil
 }
 
@@ -434,7 +465,16 @@ func (c *Calc) Result() float64 {
 			fmt.Print("= ")
 		}
 
-		fmt.Println(c.stack.Last()[0])
+		result := c.stack.Last()[0]
+		truncated := math.Trunc(result)
+		precision := c.precision
+
+		if result == truncated {
+			precision = 0
+		}
+
+		format := fmt.Sprintf("%%.%df\n", precision)
+		fmt.Printf(format, result)
 	}
 
 	return c.stack.Last()[0]
@@ -448,24 +488,26 @@ func (c *Calc) Debug(msg string) {
 
 func (c *Calc) EvalLuaFunction(funcname string) {
 	// called from calc loop
-	var x float64
+	var luaresult float64
+
 	var err error
 
 	switch c.interpreter.FuncNumArgs(funcname) {
 	case 0:
 		fallthrough
 	case 1:
-		x, err = c.interpreter.CallLuaFunc(funcname, c.stack.Last())
+		luaresult, err = c.interpreter.CallLuaFunc(funcname, c.stack.Last())
 	case 2:
-		x, err = c.interpreter.CallLuaFunc(funcname, c.stack.Last(2))
+		luaresult, err = c.interpreter.CallLuaFunc(funcname, c.stack.Last(2))
 	case -1:
-		x, err = c.interpreter.CallLuaFunc(funcname, c.stack.All())
+		luaresult, err = c.interpreter.CallLuaFunc(funcname, c.stack.All())
 	default:
-		x, err = 0, errors.New("invalid number of argument requested")
+		luaresult, err = 0, errors.New("invalid number of argument requested")
 	}
 
 	if err != nil {
 		fmt.Println(err)
+
 		return
 	}
 
@@ -476,24 +518,26 @@ func (c *Calc) EvalLuaFunction(funcname string) {
 	switch c.interpreter.FuncNumArgs(funcname) {
 	case 0:
 		a := c.stack.Last()
+
 		if len(a) == 1 {
-			c.History("%s(%f) = %f", funcname, a, x)
+			c.History("%s(%f) = %f", funcname, a, luaresult)
 		}
+
 		dopush = false
 	case 1:
 		a := c.stack.Pop()
-		c.History("%s(%f) = %f", funcname, a, x)
+		c.History("%s(%f) = %f", funcname, a, luaresult)
 	case 2:
 		a := c.stack.Pop()
 		b := c.stack.Pop()
-		c.History("%s(%f,%f) = %f", funcname, a, b, x)
+		c.History("%s(%f,%f) = %f", funcname, a, b, luaresult)
 	case -1:
 		c.stack.Clear()
-		c.History("%s(*) = %f", funcname, x)
+		c.History("%s(*) = %f", funcname, luaresult)
 	}
 
 	if dopush {
-		c.stack.Push(x)
+		c.stack.Push(luaresult)
 	}
 
 	c.Result()
@@ -511,7 +555,7 @@ func (c *Calc) PutVar(name string) {
 }
 
 func (c *Calc) GetVar(name string) {
-	if _, ok := c.Vars[name]; ok {
+	if exists(c.Vars, name) {
 		c.Debug(fmt.Sprintf("retrieve %.2f from %s", c.Vars[name], name))
 		c.stack.Backup()
 		c.stack.Push(c.Vars[name])
@@ -519,3 +563,62 @@ func (c *Calc) GetVar(name string) {
 		fmt.Println("variable doesn't exist")
 	}
 }
+
+func sortcommands(hash Commands) []string {
+	keys := make([]string, 0, len(hash))
+
+	for key := range hash {
+		if len(key) > 1 {
+			keys = append(keys, key)
+		}
+	}
+
+	sort.Strings(keys)
+
+	return keys
+}
+
+func (c *Calc) PrintHelp() {
+	fmt.Println("Available configuration commands:")
+
+	for _, name := range sortcommands(c.SettingsCommands) {
+		fmt.Printf("%-20s %s\n", name, c.SettingsCommands[name].Help)
+	}
+
+	fmt.Println()
+
+	fmt.Println("Available show commands:")
+
+	for _, name := range sortcommands(c.ShowCommands) {
+		fmt.Printf("%-20s %s\n", name, c.ShowCommands[name].Help)
+	}
+
+	fmt.Println()
+
+	fmt.Println("Available stack manipulation commands:")
+
+	for _, name := range sortcommands(c.StackCommands) {
+		fmt.Printf("%-20s %s\n", name, c.StackCommands[name].Help)
+	}
+
+	fmt.Println()
+
+	fmt.Println("Other commands:")
+
+	for _, name := range sortcommands(c.Commands) {
+		fmt.Printf("%-20s %s\n", name, c.Commands[name].Help)
+	}
+
+	fmt.Println()
+
+	fmt.Println(Help)
+
+	// append lua functions, if any
+	if len(LuaFuncs) > 0 {
+		fmt.Println("Lua functions:")
+
+		for name, function := range LuaFuncs {
+			fmt.Printf("%-20s %s\n", name, function.help)
+		}
+	}
+}

calc_test.go

@@ -19,6 +19,8 @@ package main
 
 import (
 	"fmt"
+	"strconv"
+	"strings"
 	"testing"
 
 	lua "github.com/yuin/gopher-lua"
@@ -69,20 +71,22 @@ func TestCommentsAndWhitespace(t *testing.T) {
 		},
 	}
 
-	for _, tt := range tests {
+	for _, test := range tests {
 		testname := fmt.Sprintf("%s .(expect %.2f)",
-			tt.name, tt.exp)
+			test.name, test.exp)
 
 		t.Run(testname, func(t *testing.T) {
-			for _, line := range tt.cmd {
+			for _, line := range test.cmd {
-				calc.Eval(line)
+				if err := calc.Eval(line); err != nil {
+					t.Error(err.Error())
+				}
 			}
 			got := calc.stack.Last()
 
 			if len(got) > 0 {
-				if got[0] != tt.exp {
+				if got[0] != test.exp {
 					t.Errorf("parsing failed:\n+++  got: %f\n--- want: %f",
-						got, tt.exp)
+						got, test.exp)
 				}
 			}
 
@@ -90,7 +94,6 @@ func TestCommentsAndWhitespace(t *testing.T) {
 				t.Errorf("invalid stack size:\n+++  got: %d\n--- want: 1",
 					calc.stack.Len())
 			}
-
 		})
 
 		calc.stack.Clear()
@@ -241,20 +244,61 @@ func TestCalc(t *testing.T) {
 			cmd:  `4 4 + undo *`,
 			exp:  16,
 		},
+
+		// bit tests
+		{
+			name: "bit and",
+			cmd:  `1 3 and`,
+			exp:  1,
+		},
+		{
+			name: "bit or",
+			cmd:  `1 3 or`,
+			exp:  3,
+		},
+		{
+			name: "bit xor",
+			cmd:  `1 3 xor`,
+			exp:  2,
+		},
+
+		// converters
+		{
+			name: "inch-to-cm",
+			cmd:  `111 inch-to-cm`,
+			exp:  281.94,
+		},
+		{
+			name: "gallons-to-liters",
+			cmd:  `111 gallons-to-liters`,
+			exp:  420.135,
+		},
+		{
+			name: "meters-to-yards",
+			cmd:  `111 meters-to-yards`,
+			exp:  1.2139107611548556,
+		},
+		{
+			name: "miles-to-kilometers",
+			cmd:  `111 miles-to-kilometers`,
+			exp:  178.599,
+		},
 	}
 
-	for _, tt := range tests {
+	for _, test := range tests {
 		testname := fmt.Sprintf("cmd-%s-expect-%.2f",
-			tt.name, tt.exp)
+			test.name, test.exp)
 
 		t.Run(testname, func(t *testing.T) {
-			calc.batch = tt.batch
+			calc.batch = test.batch
-			calc.Eval(tt.cmd)
+			if err := calc.Eval(test.cmd); err != nil {
+				t.Error(err.Error())
+			}
 			got := calc.Result()
 			calc.stack.Clear()
-			if got != tt.exp {
+			if got != test.exp {
 				t.Errorf("calc failed:\n+++  got: %f\n--- want: %f",
-					got, tt.exp)
+					got, test.exp)
 			}
 		})
 	}
@@ -279,23 +323,24 @@ func TestCalcLua(t *testing.T) {
 	}
 
 	calc := NewCalc()
-	L = lua.NewState(lua.Options{SkipOpenLibs: true})
+
-	defer L.Close()
+	LuaInterpreter = lua.NewState(lua.Options{SkipOpenLibs: true})
+	defer LuaInterpreter.Close()
 
 	luarunner := NewInterpreter("example.lua", false)
 	luarunner.InitLua()
 	calc.SetInt(luarunner)
 
-	for _, tt := range tests {
+	for _, test := range tests {
-		testname := fmt.Sprintf("lua-%s", tt.function)
+		testname := fmt.Sprintf("lua-%s", test.function)
 
 		t.Run(testname, func(t *testing.T) {
 			calc.stack.Clear()
-			for _, item := range tt.stack {
+			for _, item := range test.stack {
 				calc.stack.Push(item)
 			}
 
-			calc.EvalLuaFunction(tt.function)
+			calc.EvalLuaFunction(test.function)
 
 			got := calc.stack.Last()
 
@@ -304,10 +349,70 @@ func TestCalcLua(t *testing.T) {
 					calc.stack.Len())
 			}
 
-			if got[0] != tt.exp {
+			if got[0] != test.exp {
 				t.Errorf("lua function %s failed:\n+++  got: %f\n--- want: %f",
-					tt.function, got, tt.exp)
+					test.function, got, test.exp)
 			}
 		})
 	}
 }
+
+func FuzzEval(f *testing.F) {
+	legal := []string{
+		"dump",
+		"showstack",
+		"help",
+		"Pi 31 *",
+		"SqrtE Pi /",
+		"55.5 yards-to-meters",
+		"2 4 +",
+		"7 8 batch sum",
+		"7 8 %-",
+		"7 8 clear",
+		"7 8 /",
+		"b",
+		"#444",
+		"<X",
+	}
+
+	for _, item := range legal {
+		f.Add(item)
+	}
+
+	calc := NewCalc()
+
+	var hexnum, hour, min int
+
+	f.Fuzz(func(t *testing.T, line string) {
+		t.Logf("Stack:\n%v\n", calc.stack.All())
+		if err := calc.EvalItem(line); err == nil {
+			t.Logf("given: <%s>", line)
+			// not corpus and empty?
+			if !contains(legal, line) && len(line) > 0 {
+				item := strings.TrimSpace(calc.Comment.ReplaceAllString(line, ""))
+				_, hexerr := fmt.Sscanf(item, "0x%x", &hexnum)
+				_, timeerr := fmt.Sscanf(item, "%d:%d", &hour, &min)
+				// no comment?
+				if len(item) > 0 {
+					// no known command or function?
+					if _, err := strconv.ParseFloat(item, 64); err != nil {
+						if !contains(calc.Constants, item) &&
+							!exists(calc.Funcalls, item) &&
+							!exists(calc.BatchFuncalls, item) &&
+							!contains(calc.LuaFunctions, item) &&
+							!exists(calc.Commands, item) &&
+							!exists(calc.ShowCommands, item) &&
+							!exists(calc.SettingsCommands, item) &&
+							!exists(calc.StackCommands, item) &&
+							!calc.Register.MatchString(item) &&
+							item != "?" && item != "help" &&
+							hexerr != nil &&
+							timeerr != nil {
+							t.Errorf("Fuzzy input accepted: <%s>", line)
+						}
+					}
+				}
+			}
+		}
+	})
+}

command.go

@@ -0,0 +1,350 @@
+/*
+Copyright © 2023 Thomas von Dein
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"os/exec"
+	"strconv"
+	"strings"
+)
+
+type CommandFunction func(*Calc)
+
+type Command struct {
+	Help string
+	Func CommandFunction
+}
+
+type Commands map[string]*Command
+
+func NewCommand(help string, function CommandFunction) *Command {
+	return &Command{
+		Help: help,
+		Func: function,
+	}
+}
+
+func (c *Calc) SetSettingsCommands() Commands {
+	return Commands{
+		// Toggles
+		"debug": NewCommand(
+			"toggle debugging",
+			func(c *Calc) {
+				c.ToggleDebug()
+			},
+		),
+
+		"nodebug": NewCommand(
+			"disable debugging",
+			func(c *Calc) {
+				c.debug = false
+				c.stack.debug = false
+			},
+		),
+
+		"batch": NewCommand(
+			"toggle batch mode",
+			func(c *Calc) {
+				c.ToggleBatch()
+			},
+		),
+
+		"nobatch": NewCommand(
+			"disable batch mode",
+			func(c *Calc) {
+				c.batch = false
+			},
+		),
+
+		"showstack": NewCommand(
+			"toggle show last 5 items of the stack",
+			func(c *Calc) {
+				c.ToggleShow()
+			},
+		),
+
+		"noshowstack": NewCommand(
+			"disable display of the stack",
+			func(c *Calc) {
+				c.showstack = false
+			},
+		),
+	}
+}
+
+func (c *Calc) SetShowCommands() Commands {
+	return Commands{
+		// Display commands
+		"dump": NewCommand(
+			"display the stack contents",
+			func(c *Calc) {
+				c.stack.Dump()
+			},
+		),
+
+		"history": NewCommand(
+			"display calculation history",
+			func(c *Calc) {
+				for _, entry := range c.history {
+					fmt.Println(entry)
+				}
+			},
+		),
+
+		"vars": NewCommand(
+			"show list of variables",
+			func(c *Calc) {
+				if len(c.Vars) > 0 {
+					fmt.Printf("%-20s     %s\n", "VARIABLE", "VALUE")
+					for k, v := range c.Vars {
+						fmt.Printf("%-20s  -> %.2f\n", k, v)
+					}
+				} else {
+					fmt.Println("no vars registered")
+				}
+			},
+		),
+
+		"hex": NewCommand(
+			"show last stack item in hex form (converted to int)",
+			func(c *Calc) {
+				if c.stack.Len() > 0 {
+					fmt.Printf("0x%x\n", int(c.stack.Last()[0]))
+				}
+			},
+		),
+	}
+}
+
+func (c *Calc) SetStackCommands() Commands {
+	return Commands{
+		"clear": NewCommand(
+			"clear the whole stack",
+			func(c *Calc) {
+				c.stack.Backup()
+				c.stack.Clear()
+			},
+		),
+
+		"shift": NewCommand(
+			"remove the last element of the stack",
+			func(c *Calc) {
+				c.stack.Backup()
+				c.stack.Shift()
+			},
+		),
+
+		"reverse": NewCommand(
+			"reverse the stack elements",
+			func(c *Calc) {
+				c.stack.Backup()
+				c.stack.Reverse()
+			},
+		),
+
+		"swap": NewCommand(
+			"exchange the last two elements",
+			CommandSwap,
+		),
+
+		"undo": NewCommand(
+			"undo last operation",
+			func(c *Calc) {
+				c.stack.Restore()
+			},
+		),
+
+		"dup": NewCommand(
+			"duplicate last stack item",
+			CommandDup,
+		),
+
+		"edit": NewCommand(
+			"edit the stack interactively",
+			CommandEdit,
+		),
+	}
+}
+
+// define all management (that is: non calculation) commands
+func (c *Calc) SetCommands() {
+	c.SettingsCommands = c.SetSettingsCommands()
+	c.ShowCommands = c.SetShowCommands()
+	c.StackCommands = c.SetStackCommands()
+
+	// general commands
+	c.Commands = Commands{
+		"exit": NewCommand(
+			"exit program",
+			func(c *Calc) {
+				os.Exit(0)
+			},
+		),
+
+		"manual": NewCommand(
+			"show manual",
+			func(c *Calc) {
+				man()
+			},
+		),
+	}
+
+	// aliases
+	c.Commands["quit"] = c.Commands["exit"]
+
+	c.SettingsCommands["d"] = c.SettingsCommands["debug"]
+	c.SettingsCommands["b"] = c.SettingsCommands["batch"]
+	c.SettingsCommands["s"] = c.SettingsCommands["showstack"]
+
+	c.SettingsCommands["togglebatch"] = c.SettingsCommands["batch"]
+	c.SettingsCommands["toggledebug"] = c.SettingsCommands["debug"]
+	c.SettingsCommands["toggleshowstack"] = c.SettingsCommands["showstack"]
+
+	c.ShowCommands["h"] = c.ShowCommands["history"]
+	c.ShowCommands["p"] = c.ShowCommands["dump"]
+	c.ShowCommands["v"] = c.ShowCommands["vars"]
+
+	c.StackCommands["c"] = c.StackCommands["clear"]
+	c.StackCommands["u"] = c.StackCommands["undo"]
+}
+
+// added to the command map:
+func CommandSwap(c *Calc) {
+	if c.stack.Len() < 2 {
+		fmt.Println("stack too small, can't swap")
+	} else {
+		c.stack.Backup()
+		c.stack.Swap()
+	}
+}
+
+func CommandDup(c *Calc) {
+	item := c.stack.Last()
+	if len(item) == 1 {
+		c.stack.Backup()
+		c.stack.Push(item[0])
+	} else {
+		fmt.Println("stack empty")
+	}
+}
+
+func CommandEdit(calc *Calc) {
+	if calc.stack.Len() == 0 {
+		fmt.Println("empty stack")
+
+		return
+	}
+
+	calc.stack.Backup()
+
+	// put the stack contents into a tmp file
+	tmp, err := os.CreateTemp("", "stack")
+	if err != nil {
+		fmt.Println(err)
+
+		return
+	}
+
+	defer os.Remove(tmp.Name())
+
+	comment := `# add or remove numbers as you wish.
+# each number must be on its own line.
+# numbers must be floating point formatted.
+`
+	_, err = tmp.WriteString(comment)
+
+	if err != nil {
+		fmt.Println(err)
+
+		return
+	}
+
+	for _, item := range calc.stack.All() {
+		_, err = fmt.Fprintf(tmp, "%f\n", item)
+		if err != nil {
+			fmt.Println(err)
+
+			return
+		}
+	}
+
+	tmp.Close()
+
+	// determine which editor to use
+	editor := "vi"
+
+	enveditor, present := os.LookupEnv("EDITOR")
+	if present {
+		if editor != "" {
+			if _, err := os.Stat(editor); err == nil {
+				editor = enveditor
+			}
+		}
+	}
+
+	// execute editor with our tmp file containing current stack
+	cmd := exec.Command(editor, tmp.Name())
+
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+
+	err = cmd.Run()
+	if err != nil {
+		fmt.Println("could not run editor command: ", err)
+
+		return
+	}
+
+	// read the file back in
+	modified, err := os.Open(tmp.Name())
+	if err != nil {
+		fmt.Println("Error opening file:", err)
+
+		return
+	}
+	defer modified.Close()
+
+	// reset the stack
+	calc.stack.Clear()
+
+	// and put the new contents (if legit) back onto the stack
+	scanner := bufio.NewScanner(modified)
+	for scanner.Scan() {
+		line := strings.TrimSpace(calc.Comment.ReplaceAllString(scanner.Text(), ""))
+		if line == "" {
+			continue
+		}
+
+		num, err := strconv.ParseFloat(line, 64)
+		if err != nil {
+			fmt.Printf("%s is not a floating point number!\n", line)
+
+			continue
+		}
+
+		calc.stack.Push(num)
+	}
+
+	if err := scanner.Err(); err != nil {
+		fmt.Println("Error reading from file:", err)
+	}
+}

funcs.go

@@ -22,14 +22,14 @@ import (
 	"math"
 )
 
-type R struct {
+type Result struct {
 	Res float64
 	Err error
 }
 
 type Numbers []float64
 
-type Function func(Numbers) R
+type Function func(Numbers) Result
 
 // every function we  are able to call must be  of type Funcall, which
 // needs to  specify how  many numbers  it expects  and the  actual go
@@ -64,359 +64,450 @@ func NewFuncall(function Function, expectargs ...int) *Funcall {
 }
 
 // Convenience function, create new result
-func NewR(n float64, e error) R {
+func NewResult(n float64, e error) Result {
-	return R{Res: n, Err: e}
+	return Result{Res: n, Err: e}
 }
 
 // the actual functions, called once during initialization.
 func DefineFunctions() Funcalls {
-	f := map[string]*Funcall{
+	funcmap := map[string]*Funcall{
 		// simple operators, they all expect 2 args
 		"+": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(arg[0]+arg[1], nil)
+				return NewResult(arg[0]+arg[1], nil)
 			},
 		),
 
 		"-": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(arg[0]-arg[1], nil)
+				return NewResult(arg[0]-arg[1], nil)
 			},
 		),
 
 		"x": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(arg[0]*arg[1], nil)
+				return NewResult(arg[0]*arg[1], nil)
 			},
 		),
 
 		"/": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
 				if arg[1] == 0 {
-					return NewR(0, errors.New("division by null"))
+					return NewResult(0, errors.New("division by null"))
 				}
 
-				return NewR(arg[0]/arg[1], nil)
+				return NewResult(arg[0]/arg[1], nil)
 			},
 		),
 
 		"^": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Pow(arg[0], arg[1]), nil)
+				return NewResult(math.Pow(arg[0], arg[1]), nil)
 			},
 		),
 
 		"%": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR((arg[0]/100)*arg[1], nil)
+				return NewResult((arg[0]/100)*arg[1], nil)
 			},
 		),
 
 		"%-": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(arg[0]-((arg[0]/100)*arg[1]), nil)
+				return NewResult(arg[0]-((arg[0]/100)*arg[1]), nil)
 			},
 		),
 
 		"%+": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(arg[0]+((arg[0]/100)*arg[1]), nil)
+				return NewResult(arg[0]+((arg[0]/100)*arg[1]), nil)
 			},
 		),
 
 		"mod": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Remainder(arg[0], arg[1]), nil)
+				return NewResult(math.Remainder(arg[0], arg[1]), nil)
 			},
 		),
 
 		"sqrt": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Sqrt(arg[0]), nil)
+				return NewResult(math.Sqrt(arg[0]), nil)
 			},
 			1),
 
 		"abs": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Abs(arg[0]), nil)
+				return NewResult(math.Abs(arg[0]), nil)
 			},
 			1),
 
 		"acos": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Acos(arg[0]), nil)
+				return NewResult(math.Acos(arg[0]), nil)
 			},
 			1),
 
 		"acosh": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Acosh(arg[0]), nil)
+				return NewResult(math.Acosh(arg[0]), nil)
 			},
 			1),
 
 		"asin": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Asin(arg[0]), nil)
+				return NewResult(math.Asin(arg[0]), nil)
 			},
 			1),
 
 		"asinh": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Asinh(arg[0]), nil)
+				return NewResult(math.Asinh(arg[0]), nil)
 			},
 			1),
 
 		"atan": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Atan(arg[0]), nil)
+				return NewResult(math.Atan(arg[0]), nil)
 			},
 			1),
 
 		"atan2": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Atan2(arg[0], arg[1]), nil)
+				return NewResult(math.Atan2(arg[0], arg[1]), nil)
 			},
 			2),
 
 		"atanh": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Atanh(arg[0]), nil)
+				return NewResult(math.Atanh(arg[0]), nil)
 			},
 			1),
 
 		"cbrt": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Cbrt(arg[0]), nil)
+				return NewResult(math.Cbrt(arg[0]), nil)
 			},
 			1),
 
 		"ceil": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Ceil(arg[0]), nil)
+				return NewResult(math.Ceil(arg[0]), nil)
 			},
 			1),
 
 		"cos": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Cos(arg[0]), nil)
+				return NewResult(math.Cos(arg[0]), nil)
 			},
 			1),
 
 		"cosh": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Cosh(arg[0]), nil)
+				return NewResult(math.Cosh(arg[0]), nil)
 			},
 			1),
 
 		"erf": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Erf(arg[0]), nil)
+				return NewResult(math.Erf(arg[0]), nil)
 			},
 			1),
 
 		"erfc": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Erfc(arg[0]), nil)
+				return NewResult(math.Erfc(arg[0]), nil)
 			},
 			1),
 
 		"erfcinv": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Erfcinv(arg[0]), nil)
+				return NewResult(math.Erfcinv(arg[0]), nil)
 			},
 			1),
 
 		"erfinv": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Erfinv(arg[0]), nil)
+				return NewResult(math.Erfinv(arg[0]), nil)
 			},
 			1),
 
 		"exp": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Exp(arg[0]), nil)
+				return NewResult(math.Exp(arg[0]), nil)
 			},
 			1),
 
 		"exp2": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Exp2(arg[0]), nil)
+				return NewResult(math.Exp2(arg[0]), nil)
 			},
 			1),
 
 		"expm1": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Expm1(arg[0]), nil)
+				return NewResult(math.Expm1(arg[0]), nil)
 			},
 			1),
 
 		"floor": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Floor(arg[0]), nil)
+				return NewResult(math.Floor(arg[0]), nil)
 			},
 			1),
 
 		"gamma": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Gamma(arg[0]), nil)
+				return NewResult(math.Gamma(arg[0]), nil)
 			},
 			1),
 
 		"ilogb": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(float64(math.Ilogb(arg[0])), nil)
+				return NewResult(float64(math.Ilogb(arg[0])), nil)
 			},
 			1),
 
 		"j0": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.J0(arg[0]), nil)
+				return NewResult(math.J0(arg[0]), nil)
 			},
 			1),
 
 		"j1": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.J1(arg[0]), nil)
+				return NewResult(math.J1(arg[0]), nil)
 			},
 			1),
 
 		"log": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Log(arg[0]), nil)
+				return NewResult(math.Log(arg[0]), nil)
 			},
 			1),
 
 		"log10": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Log10(arg[0]), nil)
+				return NewResult(math.Log10(arg[0]), nil)
 			},
 			1),
 
 		"log1p": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Log1p(arg[0]), nil)
+				return NewResult(math.Log1p(arg[0]), nil)
 			},
 			1),
 
 		"log2": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Log2(arg[0]), nil)
+				return NewResult(math.Log2(arg[0]), nil)
 			},
 			1),
 
 		"logb": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Logb(arg[0]), nil)
+				return NewResult(math.Logb(arg[0]), nil)
 			},
 			1),
 
 		"pow": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Pow(arg[0], arg[1]), nil)
+				return NewResult(math.Pow(arg[0], arg[1]), nil)
 			},
 			2),
 
 		"round": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Round(arg[0]), nil)
+				return NewResult(math.Round(arg[0]), nil)
 			},
 			1),
 
 		"roundtoeven": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.RoundToEven(arg[0]), nil)
+				return NewResult(math.RoundToEven(arg[0]), nil)
 			},
 			1),
 
 		"sin": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Sin(arg[0]), nil)
+				return NewResult(math.Sin(arg[0]), nil)
 			},
 			1),
 
 		"sinh": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Sinh(arg[0]), nil)
+				return NewResult(math.Sinh(arg[0]), nil)
 			},
 			1),
 
 		"tan": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Tan(arg[0]), nil)
+				return NewResult(math.Tan(arg[0]), nil)
 			},
 			1),
 
 		"tanh": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Tanh(arg[0]), nil)
+				return NewResult(math.Tanh(arg[0]), nil)
 			},
 			1),
 
 		"trunc": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Trunc(arg[0]), nil)
+				return NewResult(math.Trunc(arg[0]), nil)
 			},
 			1),
 
 		"y0": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Y0(arg[0]), nil)
+				return NewResult(math.Y0(arg[0]), nil)
 			},
 			1),
 
 		"y1": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Y1(arg[0]), nil)
+				return NewResult(math.Y1(arg[0]), nil)
 			},
 			1),
 
 		"copysign": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Copysign(arg[0], arg[1]), nil)
+				return NewResult(math.Copysign(arg[0], arg[1]), nil)
 			},
 			2),
 
 		"dim": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Dim(arg[0], arg[1]), nil)
+				return NewResult(math.Dim(arg[0], arg[1]), nil)
 			},
 			2),
 
 		"hypot": NewFuncall(
-			func(arg Numbers) R {
+			func(arg Numbers) Result {
-				return NewR(math.Hypot(arg[0], arg[1]), nil)
+				return NewResult(math.Hypot(arg[0], arg[1]), nil)
+			},
+			2),
+
+		// converters of all kinds
+		"cm-to-inch": NewFuncall(
+			func(arg Numbers) Result {
+				return NewResult(arg[0]/2.54, nil)
+			},
+			1),
+
+		"inch-to-cm": NewFuncall(
+			func(arg Numbers) Result {
+				return NewResult(arg[0]*2.54, nil)
+			},
+			1),
+
+		"gallons-to-liters": NewFuncall(
+			func(arg Numbers) Result {
+				return NewResult(arg[0]*3.785, nil)
+			},
+			1),
+
+		"liters-to-gallons": NewFuncall(
+			func(arg Numbers) Result {
+				return NewResult(arg[0]/3.785, nil)
+			},
+			1),
+
+		"yards-to-meters": NewFuncall(
+			func(arg Numbers) Result {
+				return NewResult(arg[0]*91.44, nil)
+			},
+			1),
+
+		"meters-to-yards": NewFuncall(
+			func(arg Numbers) Result {
+				return NewResult(arg[0]/91.44, nil)
+			},
+			1),
+
+		"miles-to-kilometers": NewFuncall(
+			func(arg Numbers) Result {
+				return NewResult(arg[0]*1.609, nil)
+			},
+			1),
+
+		"kilometers-to-miles": NewFuncall(
+			func(arg Numbers) Result {
+				return NewResult(arg[0]/1.609, nil)
+			},
+			1),
+
+		"or": NewFuncall(
+			func(arg Numbers) Result {
+				return NewResult(float64(int(arg[0])|int(arg[1])), nil)
+			},
+			2),
+
+		"and": NewFuncall(
+			func(arg Numbers) Result {
+				return NewResult(float64(int(arg[0])&int(arg[1])), nil)
+			},
+			2),
+
+		"xor": NewFuncall(
+			func(arg Numbers) Result {
+				return NewResult(float64(int(arg[0])^int(arg[1])), nil)
+			},
+			2),
+
+		"<": NewFuncall(
+			func(arg Numbers) Result {
+				// Shift by negative number provibited, so check it.
+				// Note that we check against uint64 overflow as well here
+				if arg[1] < 0 || uint64(arg[1]) > math.MaxInt64 {
+					return NewResult(0, errors.New("negative shift amount"))
+				}
+
+				return NewResult(float64(int(arg[0])<<int(arg[1])), nil)
+			},
+			2),
+
+		">": NewFuncall(
+			func(arg Numbers) Result {
+				if arg[1] < 0 || uint64(arg[1]) > math.MaxInt64 {
+					return NewResult(0, errors.New("negative shift amount"))
+				}
+
+				return NewResult(float64(int(arg[0])>>int(arg[1])), nil)
 			},
 			2),
 	}
 
 	// aliases
-	f["*"] = f["x"]
+	funcmap["*"] = funcmap["x"]
-	f["remainder"] = f["mod"]
+	funcmap["remainder"] = funcmap["mod"]
 
-	return f
+	return funcmap
 }
 
 func DefineBatchFunctions() Funcalls {
-	f := map[string]*Funcall{
+	funcmap := map[string]*Funcall{
 		"median": NewFuncall(
-			func(args Numbers) R {
+			func(args Numbers) Result {
 				middle := len(args) / 2
-				return NewR(args[middle], nil)
+
+				return NewResult(args[middle], nil)
 			},
 			-1),
 
 		"mean": NewFuncall(
-			func(args Numbers) R {
+			func(args Numbers) Result {
 				var sum float64
 				for _, item := range args {
 					sum += item
 				}
-				return NewR(sum/float64(len(args)), nil)
+
+				return NewResult(sum/float64(len(args)), nil)
 			},
 			-1),
 
 		"min": NewFuncall(
-			func(args Numbers) R {
+			func(args Numbers) Result {
 				var min float64
 				min, args = args[0], args[1:]
 				for _, item := range args {
@@ -424,12 +515,13 @@ func DefineBatchFunctions() Funcalls {
 						min = item
 					}
 				}
-				return NewR(min, nil)
+
+				return NewResult(min, nil)
 			},
 			-1),
 
 		"max": NewFuncall(
-			func(args Numbers) R {
+			func(args Numbers) Result {
 				var max float64
 				max, args = args[0], args[1:]
 				for _, item := range args {
@@ -437,24 +529,26 @@ func DefineBatchFunctions() Funcalls {
 						max = item
 					}
 				}
-				return NewR(max, nil)
+
+				return NewResult(max, nil)
 			},
 			-1),
 
 		"sum": NewFuncall(
-			func(args Numbers) R {
+			func(args Numbers) Result {
 				var sum float64
 				for _, item := range args {
 					sum += item
 				}
-				return NewR(sum, nil)
+
+				return NewResult(sum, nil)
 			},
 			-1),
 	}
 
 	// aliases
-	f["+"] = f["sum"]
+	funcmap["+"] = funcmap["sum"]
-	f["avg"] = f["mean"]
+	funcmap["avg"] = funcmap["mean"]
 
-	return f
+	return funcmap
 }

go.mod

@@ -1,10 +1,15 @@
 module rpn
 
-go 1.20
+go 1.22
 
 require (
-	github.com/chzyer/readline v1.5.1 // indirect
+	github.com/chzyer/readline v1.5.1
-	github.com/spf13/pflag v1.0.5 // indirect
+	github.com/rogpeppe/go-internal v1.13.1
-	github.com/yuin/gopher-lua v1.1.0 // indirect
+	github.com/spf13/pflag v1.0.6
-	golang.org/x/sys v0.0.0-20220310020820-b874c991c1a5 // indirect
+	github.com/yuin/gopher-lua v1.1.1
+)
+
+require (
+	golang.org/x/sys v0.21.0 // indirect
+	golang.org/x/tools v0.22.0 // indirect
 )

go.sum

@@ -1,10 +1,17 @@
+github.com/chzyer/logex v1.2.1 h1:XHDu3E6q+gdHgsdTPH6ImJMIp436vR6MPtH8gP05QzM=
 github.com/chzyer/logex v1.2.1/go.mod h1:JLbx6lG2kDbNRFnfkgvh4eRJRPX1QCoOIWomwysCBrQ=
 github.com/chzyer/readline v1.5.1 h1:upd/6fQk4src78LMRzh5vItIt361/o4uq553V8B5sGI=
 github.com/chzyer/readline v1.5.1/go.mod h1:Eh+b79XXUwfKfcPLepksvw2tcLE/Ct21YObkaSkeBlk=
+github.com/chzyer/test v1.0.0 h1:p3BQDXSxOhOG0P9z6/hGnII4LGiEPOYBhs8asl/fC04=
 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/rogpeppe/go-internal v1.13.1 h1:KvO1DLK/DRN07sQ1LQKScxyZJuNnedQ5/wKSR38lUII=
-github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+github.com/rogpeppe/go-internal v1.13.1/go.mod h1:uMEvuHeurkdAXX61udpOXGD/AzZDWNMNyH2VO9fmH0o=
-github.com/yuin/gopher-lua v1.1.0 h1:BojcDhfyDWgU2f2TOzYK/g5p2gxMrku8oupLDqlnSqE=
+github.com/spf13/pflag v1.0.6 h1:jFzHGLGAlb3ruxLB8MhbI6A8+AQX/2eW4qeyNZXNp2o=
-github.com/yuin/gopher-lua v1.1.0/go.mod h1:GBR0iDaNXjAgGg9zfCvksxSRnQx76gclCIb7kdAd1Pw=
+github.com/spf13/pflag v1.0.6/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
-golang.org/x/sys v0.0.0-20220310020820-b874c991c1a5 h1:y/woIyUBFbpQGKS0u1aHF/40WUDnek3fPOyD08H5Vng=
+github.com/yuin/gopher-lua v1.1.1 h1:kYKnWBjvbNP4XLT3+bPEwAXJx262OhaHDWDVOPjL46M=
+github.com/yuin/gopher-lua v1.1.1/go.mod h1:GBR0iDaNXjAgGg9zfCvksxSRnQx76gclCIb7kdAd1Pw=
 golang.org/x/sys v0.0.0-20220310020820-b874c991c1a5/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.21.0 h1:rF+pYz3DAGSQAxAu1CbC7catZg4ebC4UIeIhKxBZvws=
+golang.org/x/sys v0.21.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/tools v0.22.0 h1:gqSGLZqv+AI9lIQzniJ0nZDRG5GBPsSi+DRNHWNz6yA=
+golang.org/x/tools v0.22.0/go.mod h1:aCwcsjqvq7Yqt6TNyX7QMU2enbQ/Gt0bo6krSeEri+c=

interpreter.go

@@ -29,8 +29,8 @@ type Interpreter struct {
 	script string
 }
 
-// LUA interpreter, instanciated in main()
+// LuaInterpreter is the lua interpreter, instantiated in main()
-var L *lua.LState
+var LuaInterpreter *lua.LState
 
 // holds a user provided lua function
 type LuaFunction struct {
@@ -39,8 +39,8 @@ type LuaFunction struct {
 	numargs int
 }
 
-// must be global since init() is  being called from lua which doesn't
+// LuaFuncs must be global since init() is being called from lua which
-// have access to the interpreter instance
+// doesn't have access to the interpreter instance
 var LuaFuncs map[string]LuaFunction
 
 func NewInterpreter(script string, debug bool) *Interpreter {
@@ -61,8 +61,8 @@ func (i *Interpreter) InitLua() {
 		{lua.DebugLibName, lua.OpenDebug},
 		{lua.MathLibName, lua.OpenMath},
 	} {
-		if err := L.CallByParam(lua.P{
+		if err := LuaInterpreter.CallByParam(lua.P{
-			Fn:      L.NewFunction(pair.f),
+			Fn:      LuaInterpreter.NewFunction(pair.f),
 			NRet:    0,
 			Protect: true,
 		}, lua.LString(pair.n)); err != nil {
@@ -71,19 +71,19 @@ func (i *Interpreter) InitLua() {
 	}
 
 	// load the lua config (which we expect to contain init() and math functions)
-	if err := L.DoFile(i.script); err != nil {
+	if err := LuaInterpreter.DoFile(i.script); err != nil {
 		panic(err)
 	}
 
-	// instanciate
+	// instantiate
 	LuaFuncs = map[string]LuaFunction{}
 
 	// that way the user can call register(...) from lua inside init()
-	L.SetGlobal("register", L.NewFunction(register))
+	LuaInterpreter.SetGlobal("register", LuaInterpreter.NewFunction(register))
 
 	// actually call init()
-	if err := L.CallByParam(lua.P{
+	if err := LuaInterpreter.CallByParam(lua.P{
-		Fn:      L.GetGlobal("init"),
+		Fn:      LuaInterpreter.GetGlobal("init"),
 		NRet:    0,
 		Protect: true,
 	}); err != nil {
@@ -108,56 +108,54 @@ func (i *Interpreter) FuncNumArgs(name string) int {
 // arguments. 1 uses the last item of the stack, 2 the last two and -1
 // all items (which translates to batch mode)
 //
-// The  items  array  will  be   provded  by  calc.Eval(),  these  are
+// The  items  array  will  be  provided  by  calc.Eval(),  these  are
 // non-popped stack  items. So  the items will  only removed  from the
-// stack when the lua function execution is successfull.
+// stack when the lua function execution is successful.
 func (i *Interpreter) CallLuaFunc(funcname string, items []float64) (float64, error) {
 	i.Debug(fmt.Sprintf("calling lua func %s() with %d args",
 		funcname, LuaFuncs[funcname].numargs))
 
 	switch LuaFuncs[funcname].numargs {
-	case 0:
+	case 0, 1:
-		fallthrough
-	case 1:
 		// 1 arg variant
-		if err := L.CallByParam(lua.P{
+		if err := LuaInterpreter.CallByParam(lua.P{
-			Fn:      L.GetGlobal(funcname),
+			Fn:      LuaInterpreter.GetGlobal(funcname),
 			NRet:    1,
 			Protect: true,
 		}, lua.LNumber(items[0])); err != nil {
-			fmt.Println(err)
+			return 0, fmt.Errorf("failed to exec lua func %s: %w", funcname, err)
-			return 0, err
 		}
 	case 2:
 		// 2 arg variant
-		if err := L.CallByParam(lua.P{
+		if err := LuaInterpreter.CallByParam(lua.P{
-			Fn:      L.GetGlobal(funcname),
+			Fn:      LuaInterpreter.GetGlobal(funcname),
 			NRet:    1,
 			Protect: true,
 		}, lua.LNumber(items[0]), lua.LNumber(items[1])); err != nil {
-			return 0, err
+			return 0, fmt.Errorf("failed to exec lua func %s: %w", funcname, err)
 		}
 	case -1:
 		// batch variant, use lua table as array
-		tb := L.NewTable()
+		table := LuaInterpreter.NewTable()
 
 		// put the whole stack into it
 		for _, item := range items {
-			tb.Append(lua.LNumber(item))
+			table.Append(lua.LNumber(item))
 		}
 
-		if err := L.CallByParam(lua.P{
+		if err := LuaInterpreter.CallByParam(lua.P{
-			Fn:      L.GetGlobal(funcname),
+			Fn:      LuaInterpreter.GetGlobal(funcname),
 			NRet:    1,
 			Protect: true,
-		}, tb); err != nil {
+		}, table); err != nil {
-			return 0, err
+			return 0, fmt.Errorf("failed to exec lua func %s: %w", funcname, err)
 		}
 	}
 
 	// get result and cast to float64
-	if res, ok := L.Get(-1).(lua.LNumber); ok {
+	if res, ok := LuaInterpreter.Get(-1).(lua.LNumber); ok {
-		L.Pop(1)
+		LuaInterpreter.Pop(1)
+
 		return float64(res), nil
 	}
 
@@ -167,10 +165,10 @@ func (i *Interpreter) CallLuaFunc(funcname string, items []float64) (float64, er
 // called from lua to register a math  function numargs may be 1, 2 or
 // -1, it denotes the number of  items from the stack requested by the
 // lua function. -1 means batch mode, that is all items
-func register(L *lua.LState) int {
+func register(lstate *lua.LState) int {
-	function := L.ToString(1)
+	function := lstate.ToString(1)
-	numargs := L.ToInt(2)
+	numargs := lstate.ToInt(2)
-	help := L.ToString(3)
+	help := lstate.ToString(3)
 
 	LuaFuncs[function] = LuaFunction{
 		name:    function,

main.go

@@ -1,5 +1,5 @@
 /*
-Copyright © 2023 Thomas von Dein
+Copyright © 2023-2024 Thomas von Dein
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -30,7 +30,7 @@ import (
 	lua "github.com/yuin/gopher-lua"
 )
 
-const VERSION string = "2.0.7"
+const VERSION string = "2.1.4"
 
 const Usage string = `This is rpn, a reverse polish notation calculator cli.
 
@@ -42,15 +42,21 @@ Options:
   -s, --stack           show last 5 items of the stack (off by default)
   -i  --intermediate    print intermediate results
   -m, --manual          show manual
+  -c, --config <file>   load <file> containing LUA code
+  -p, --precision <int> floating point number precision (default 2)
   -v, --version         show version
   -h, --help            show help
 
 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) 2023-2025 T.v.Dein`
 
 func main() {
+	os.Exit(Main())
+}
+
+func Main() int {
 	calc := NewCalc()
 
 	showversion := false
@@ -69,17 +75,20 @@ func main() {
 	flag.BoolVarP(&showmanual, "manual", "m", false, "show manual")
 	flag.StringVarP(&configfile, "config", "c",
 		os.Getenv("HOME")+"/.rpn.lua", "config file (lua format)")
+	flag.IntVarP(&calc.precision, "precision", "p", Precision, "floating point precision")
 
 	flag.Parse()
 
 	if showversion {
 		fmt.Printf("This is rpn version %s\n", VERSION)
-		return
+
+		return 0
 	}
 
 	if showhelp {
 		fmt.Println(Usage)
-		return
+
+		return 0
 	}
 
 	if enabledebug {
@@ -88,12 +97,13 @@ func main() {
 
 	if showmanual {
 		man()
-		os.Exit(0)
+
+		return 0
 	}
 
-	// the lua state object is global, instanciate it early
+	// the lua state object is global, instantiate it early
-	L = lua.NewState(lua.Options{SkipOpenLibs: true})
+	LuaInterpreter = lua.NewState(lua.Options{SkipOpenLibs: true})
-	defer L.Close()
+	defer LuaInterpreter.Close()
 
 	// our config file is interpreted  as lua code, only functions can
 	// be defined, init() will be called by InitLua().
@@ -101,18 +111,29 @@ func main() {
 		luarunner := NewInterpreter(configfile, enabledebug)
 		luarunner.InitLua()
 		calc.SetInt(luarunner)
+
+		if calc.debug {
+			fmt.Println("loaded config")
+		}
+	} else if calc.debug {
+		fmt.Println(err)
 	}
 
 	if len(flag.Args()) > 1 {
 		// commandline calc operation, no readline etc needed
 		// called like rpn 2 2 +
 		calc.stdin = true
-		calc.Eval(strings.Join(flag.Args(), " "))
+		if err := calc.Eval(strings.Join(flag.Args(), " ")); err != nil {
-		return
+			fmt.Println(err)
+
+			return 1
+		}
+
+		return 0
 	}
 
 	// interactive mode, need readline
-	rl, err := readline.NewEx(&readline.Config{
+	reader, err := readline.NewEx(&readline.Config{
 		Prompt:            calc.Prompt(),
 		HistoryFile:       os.Getenv("HOME") + "/.rpn-history",
 		HistoryLimit:      500,
@@ -125,8 +146,8 @@ func main() {
 	if err != nil {
 		panic(err)
 	}
-	defer rl.Close()
+	defer reader.Close()
-	rl.CaptureExitSignal()
+	reader.CaptureExitSignal()
 
 	if inputIsStdin() {
 		// commands are  coming on stdin, however we  will still enter
@@ -136,13 +157,17 @@ func main() {
 
 	for {
 		// primary program repl
-		line, err := rl.Readline()
+		line, err := reader.Readline()
 		if err != nil {
 			break
 		}
 
-		calc.Eval(line)
+		err = calc.Eval(line)
-		rl.SetPrompt(calc.Prompt())
+		if err != nil {
+			fmt.Println(err)
+		}
+
+		reader.SetPrompt(calc.Prompt())
 	}
 
 	if len(flag.Args()) > 0 {
@@ -150,23 +175,31 @@ func main() {
 		// echo 1 2 3 4 | rpn +
 		// batch mode enabled automatically
 		calc.batch = true
-		calc.Eval(flag.Args()[0])
+		if err = calc.Eval(flag.Args()[0]); err != nil {
+			fmt.Println(err)
+
+			return 1
 		}
+	}
+
+	return 0
 }
 
 func inputIsStdin() bool {
 	stat, _ := os.Stdin.Stat()
+
 	return (stat.Mode() & os.ModeCharDevice) == 0
 }
 
 func man() {
+	var buf bytes.Buffer
+
 	man := exec.Command("less", "-")
 
-	var b bytes.Buffer
+	buf.WriteString(manpage)
-	b.Write([]byte(manpage))
 
 	man.Stdout = os.Stdout
-	man.Stdin = &b
+	man.Stdin = &buf
 	man.Stderr = os.Stderr
 
 	err := man.Run()

main_test.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"os"
+	"testing"
+
+	"github.com/rogpeppe/go-internal/testscript"
+)
+
+func TestMain(m *testing.M) {
+	os.Exit(testscript.RunMain(m, map[string]func() int{
+		"testrpn": Main,
+	}))
+}
+
+func TestRpn(t *testing.T) {
+	testscript.Run(t, testscript.Params{
+		Dir: "t",
+	})
+}

rpn.go

@@ -13,6 +13,8 @@ SYNOPSIS
           -s, --stack           show last 5 items of the stack (off by default)
           -i  --intermediate    print intermediate results
           -m, --manual          show manual
+          -c, --config <file>   load <file> containing LUA code
+          -p, --precision <int> floating point number precision (default 2)
           -v, --version         show version
           -h, --help            show help
     
@@ -105,6 +107,10 @@ DESCRIPTION
     If the first parameter to rpn is a math operator or function, batch mode
     is enabled automatically, see last example.
 
+    You can enter integers, floating point numbers (positive or negative) or
+    hex numbers (prefixed with 0x). Time values in hh::mm format are
+    possible as well.
+
   STACK MANIPULATION
     There are lots of stack manipulation commands provided. The most
     important one is undo which goes back to the stack before the last math
@@ -124,15 +130,23 @@ DESCRIPTION
     Basic operators:
 
         +                    add
-        -                    substract
+        -                    subtract
         /                    divide
         x                    multiply (alias: *)
         ^                    power
 
+    Bitwise operators:
+
+        and                  bitwise and
+        or                   bitwise or
+        xor                  bitwise xor
+        <                    left shift
+        >                    right shift
+
     Percent functions:
 
         %                    percent
-        %-                   substract percent
+        %-                   subtract percent
         %+                   add percent
 
     Batch functions:
@@ -150,18 +164,44 @@ DESCRIPTION
         log10 log1p log2 logb pow round roundtoeven sin sinh tan tanh trunc y0
         y1 copysign dim hypot
 
-    Commands:
+    Conversion functions:
+
+        cm-to-inch
+        inch-to-cm
+        gallons-to-liters
+        liters-to-gallons
+        yards-to-meters
+        meters-to-yards
+        miles-to-kilometers
+        kilometers-to-miles
+
+    Configuration Commands:
+
+        [no]batch            toggle batch mode (nobatch turns it off)
+        [no]debug            toggle debug output (nodebug turns it off)
+        [no]showstack        show the last 5 items of the stack (noshowtack turns it off)
+
+    Show commands:
 
-        batch                toggle batch mode
-        debug                toggle debug output
         dump                 display the stack contents
+        hex                  show last stack item in hex form (converted to int)
+        history              display calculation history
+        vars                 show list of variables
+
+    Stack manipulation commands:
+
         clear                clear the whole stack
         shift                remove the last element of the stack
         reverse              reverse the stack elements
         swap                 exchange the last two stack elements
-        show                 show the last 5 items of the stack
+        dup                  duplicate last stack item
-        history              display calculation history
+        undo                 undo last operation
+        edit                 edit the stack interactively using vi or $EDITOR
+
+    Other commands:
+
         help|?               show this message
+        manual               show manual
         quit|exit|c-d|c-c    exit program
 
     Register variables:
@@ -171,6 +211,17 @@ DESCRIPTION
 
     Refer to https://pkg.go.dev/math for details about those functions.
 
+    There are also a number of shortcuts for some commands available:
+
+        d    debug
+        b    batch
+        s    showstack
+        h    history
+        p    dump (aka print)
+        v    vars
+        c    clear
+        u    undo
+
 INTERACTIVE REPL
     While you can use rpn in the command-line, the best experience you'll
     have is the interactive repl (read eval print loop). Just execute "rpn"
@@ -261,6 +312,15 @@ EXTENDING RPN USING LUA
     So you can't open files, execute other programs or open a connection to
     the outside!
 
+CONFIGURATION
+    rpn can be configured via command line flags (see usage above). Most of
+    the flags are also available as interactive commands, such as "--batch"
+    has the same effect as the batch command.
+
+    The floating point number precision option "-p, --precision" however is
+    not available as interactive command, it MUST be configured on the
+    command line, if needed. The default precision is 2.
+
 GETTING HELP
     In interactive mode you can enter the help command (or ?) to get a short
     help along with a list of all supported operators and functions.
@@ -280,7 +340,7 @@ LICENSE
     This software is licensed under the GNU GENERAL PUBLIC LICENSE version
     3.
 
-    Copyright (c) 2023 by Thomas von Dein
+    Copyright (c) 2023-2024 by Thomas von Dein
 
     This software uses the following GO modules:
 

rpn.pod

@@ -12,6 +12,8 @@ rpn - Programmable command-line calculator using reverse polish notation
       -s, --stack           show last 5 items of the stack (off by default)
       -i  --intermediate    print intermediate results
       -m, --manual          show manual
+      -c, --config <file>   load <file> containing LUA code
+      -p, --precision <int> floating point number precision (default 2)
       -v, --version         show version
       -h, --help            show help
     
@@ -109,6 +111,10 @@ Example of batch mode usage:
 If the first parameter to rpn is a math operator or function, batch
 mode is enabled automatically, see last example.
 
+You can enter integers, floating  point numbers (positive or negative)
+or hex  numbers (prefixed with 0x).  Time values in hh::mm  format are
+possible as well.
+
 =head2 STACK MANIPULATION
 
 There are lots of stack manipulation commands provided. The most
@@ -131,15 +137,23 @@ stack.
 Basic operators:
 
     +                    add
-    -                    substract
+    -                    subtract
     /                    divide
     x                    multiply (alias: *)
     ^                    power
 
+Bitwise operators:
+
+    and                  bitwise and
+    or                   bitwise or
+    xor                  bitwise xor
+    <                    left shift
+    >                    right shift
+
 Percent functions:
 
     %                    percent
-    %-                   substract percent
+    %-                   subtract percent
     %+                   add percent
 
 Batch functions:
@@ -157,18 +171,44 @@ Math functions:
     log10 log1p log2 logb pow round roundtoeven sin sinh tan tanh trunc y0
     y1 copysign dim hypot
 
-Commands:
+Conversion functions:
+
+    cm-to-inch
+    inch-to-cm
+    gallons-to-liters
+    liters-to-gallons
+    yards-to-meters
+    meters-to-yards
+    miles-to-kilometers
+    kilometers-to-miles
+
+Configuration Commands:
+
+    [no]batch            toggle batch mode (nobatch turns it off)
+    [no]debug            toggle debug output (nodebug turns it off)
+    [no]showstack        show the last 5 items of the stack (noshowtack turns it off)
+
+Show commands:
 
-    batch                toggle batch mode
-    debug                toggle debug output
     dump                 display the stack contents
+    hex                  show last stack item in hex form (converted to int)
+    history              display calculation history
+    vars                 show list of variables
+
+Stack manipulation commands:
+
     clear                clear the whole stack
     shift                remove the last element of the stack
     reverse              reverse the stack elements
     swap                 exchange the last two stack elements
-    show                 show the last 5 items of the stack
+    dup                  duplicate last stack item
-    history              display calculation history
+    undo                 undo last operation
+    edit                 edit the stack interactively using vi or $EDITOR
+
+Other commands:
+
     help|?               show this message
+    manual               show manual
     quit|exit|c-d|c-c    exit program
 
 
@@ -179,6 +219,17 @@ Register variables:
 
 Refer to https://pkg.go.dev/math for details about those functions.
 
+There are also a number of shortcuts for some commands available:
+
+    d    debug
+    b    batch
+    s    showstack
+    h    history
+    p    dump (aka print)
+    v    vars
+    c    clear
+    u    undo
+
 =head1 INTERACTIVE REPL
 
 While you can use rpn in the command-line, the best experience you'll
@@ -294,6 +345,16 @@ B<Please note, that io, networking and system stuff is not allowed
 though. So you can't open files, execute other programs or open a
 connection to the outside!>
 
+=head1 CONFIGURATION
+
+B<rpn> can be configured via command line flags (see usage
+above). Most of the flags are also available as interactive commands,
+such as C<--batch> has the same effect as the B<batch> command.
+
+The floating point number  precision option C<-p, --precision> however
+is not available as interactive command,  it MUST be configured on the
+command line, if needed. The default precision is 2.
+
 =head1 GETTING HELP
 
 In interactive mode you can enter the B<help> command (or B<?>) to get
@@ -316,7 +377,7 @@ L<https://github.com/TLINDEN/rpnc/issues>.
 
 This software is licensed under the GNU GENERAL PUBLIC LICENSE version 3.
 
-Copyright (c) 2023 by Thomas von Dein
+Copyright (c) 2023-2024 by Thomas von Dein
 
 This software uses the following GO modules:
 

stack.go

@@ -64,14 +64,14 @@ func (s *Stack) Bump() {
 }
 
 // append an item to the stack
-func (s *Stack) Push(x float64) {
+func (s *Stack) Push(item float64) {
 	s.mutex.Lock()
 	defer s.mutex.Unlock()
 
-	s.Debug(fmt.Sprintf("     push to stack: %.2f", x))
+	s.Debug(fmt.Sprintf("     push to stack: %.2f", item))
 
 	s.Bump()
-	s.linklist.PushBack(x)
+	s.linklist.PushBack(item)
 }
 
 // remove and return an item from the stack
@@ -90,6 +90,7 @@ func (s *Stack) Pop() float64 {
 	s.Debug(fmt.Sprintf(" remove from stack: %.2f", val))
 
 	s.Bump()
+
 	return val.(float64)
 }
 
@@ -123,32 +124,33 @@ func (s *Stack) Swap() {
 		return
 	}
 
-	a := s.linklist.Back()
+	prevA := s.linklist.Back()
-	s.linklist.Remove(a)
+	s.linklist.Remove(prevA)
 
-	b := s.linklist.Back()
+	prevB := s.linklist.Back()
-	s.linklist.Remove(b)
+	s.linklist.Remove(prevB)
 
-	s.Debug(fmt.Sprintf("swapping %.2f with %.2f", b.Value, a.Value))
+	s.Debug(fmt.Sprintf("swapping %.2f with %.2f", prevB.Value, prevA.Value))
 
-	s.linklist.PushBack(a.Value)
+	s.linklist.PushBack(prevA.Value)
-	s.linklist.PushBack(b.Value)
+	s.linklist.PushBack(prevB.Value)
 }
 
 // Return the last num items from the stack w/o modifying it.
 func (s *Stack) Last(num ...int) []float64 {
 	items := []float64{}
-	i := s.Len()
+	stacklen := s.Len()
 	count := 1
+
 	if len(num) > 0 {
 		count = num[0]
 	}
 
 	for e := s.linklist.Front(); e != nil; e = e.Next() {
-		if i <= count {
+		if stacklen <= count {
 			items = append(items, e.Value.(float64))
 		}
-		i--
+		stacklen--
 	}
 
 	return items
@@ -168,12 +170,14 @@ func (s *Stack) All() []float64 {
 // dump the stack to stdout, including backup if debug is enabled
 func (s *Stack) Dump() {
 	fmt.Printf("Stack revision %d (%p):\n", s.rev, &s.linklist)
+
 	for e := s.linklist.Front(); e != nil; e = e.Next() {
 		fmt.Println(e.Value)
 	}
 
 	if s.debug {
 		fmt.Printf("Backup stack revision %d (%p):\n", s.backuprev, &s.backup)
+
 		for e := s.backup.Front(); e != nil; e = e.Next() {
 			fmt.Println(e.Value)
 		}
@@ -215,6 +219,7 @@ func (s *Stack) Restore() {
 
 	if s.rev == 0 {
 		fmt.Println("error: stack is empty.")
+
 		return
 	}
 

stack_test.go

@@ -35,16 +35,16 @@ func TestPush(t *testing.T) {
 
 func TestPop(t *testing.T) {
 	t.Run("pop", func(t *testing.T) {
-		s := NewStack()
+		stack := NewStack()
-		s.Push(5)
+		stack.Push(5)
-		got := s.Pop()
+		got := stack.Pop()
 
 		if got != 5.0 {
 			t.Errorf("pop failed:\n+++  got: %f\n--- want: %f",
 				got, 5.0)
 		}
 
-		if s.Len() != 0 {
+		if stack.Len() != 0 {
 			t.Errorf("stack not empty after pop()")
 		}
 	})
@@ -52,25 +52,25 @@ func TestPop(t *testing.T) {
 
 func TestPops(t *testing.T) {
 	t.Run("pops", func(t *testing.T) {
-		s := NewStack()
+		stack := NewStack()
-		s.Push(5)
+		stack.Push(5)
-		s.Push(5)
+		stack.Push(5)
-		s.Push(5)
+		stack.Push(5)
-		s.Pop()
+		stack.Pop()
 
-		if s.Len() != 2 {
+		if stack.Len() != 2 {
 			t.Errorf("stack len not correct after pop:\n+++  got: %d\n--- want: %d",
-				s.Len(), 2)
+				stack.Len(), 2)
 		}
 	})
 }
 
 func TestShift(t *testing.T) {
 	t.Run("shift", func(t *testing.T) {
-		s := NewStack()
+		stack := NewStack()
-		s.Shift()
+		stack.Shift()
 
-		if s.Len() != 0 {
+		if stack.Len() != 0 {
 			t.Errorf("stack not empty after shift()")
 		}
 	})
@@ -78,13 +78,13 @@ func TestShift(t *testing.T) {
 
 func TestClear(t *testing.T) {
 	t.Run("clear", func(t *testing.T) {
-		s := NewStack()
+		stack := NewStack()
-		s.Push(5)
+		stack.Push(5)
-		s.Push(5)
+		stack.Push(5)
-		s.Push(5)
+		stack.Push(5)
-		s.Clear()
+		stack.Clear()
 
-		if s.Len() != 0 {
+		if stack.Len() != 0 {
 			t.Errorf("stack not empty after clear()")
 		}
 	})
@@ -92,9 +92,9 @@ func TestClear(t *testing.T) {
 
 func TestLast(t *testing.T) {
 	t.Run("last", func(t *testing.T) {
-		s := NewStack()
+		stack := NewStack()
-		s.Push(5)
+		stack.Push(5)
-		got := s.Last()
+		got := stack.Last()
 
 		if len(got) != 1 {
 			t.Errorf("last failed:\n+++  got: %d elements\n--- want: %d elements",
@@ -106,7 +106,7 @@ func TestLast(t *testing.T) {
 				got, 5.0)
 		}
 
-		if s.Len() != 1 {
+		if stack.Len() != 1 {
 			t.Errorf("stack modified after last()")
 		}
 	})
@@ -114,14 +114,14 @@ func TestLast(t *testing.T) {
 
 func TestAll(t *testing.T) {
 	t.Run("all", func(t *testing.T) {
-		s := NewStack()
+		stack := NewStack()
 		list := []float64{2, 4, 6, 8}
 
 		for _, item := range list {
-			s.Push(item)
+			stack.Push(item)
 		}
 
-		got := s.All()
+		got := stack.All()
 
 		if len(got) != len(list) {
 			t.Errorf("all failed:\n+++  got: %d elements\n--- want: %d elements",
@@ -135,7 +135,7 @@ func TestAll(t *testing.T) {
 			}
 		}
 
-		if s.Len() != len(list) {
+		if stack.Len() != len(list) {
 			t.Errorf("stack modified after last()")
 		}
 	})
@@ -143,37 +143,37 @@ func TestAll(t *testing.T) {
 
 func TestBackupRestore(t *testing.T) {
 	t.Run("shift", func(t *testing.T) {
-		s := NewStack()
+		stack := NewStack()
-		s.Push(5)
+		stack.Push(5)
-		s.Backup()
+		stack.Backup()
-		s.Clear()
+		stack.Clear()
-		s.Restore()
+		stack.Restore()
 
-		if s.Len() != 1 {
+		if stack.Len() != 1 {
 			t.Errorf("stack not correctly restored()")
 		}
 
-		a := s.Pop()
+		value := stack.Pop()
-		if a != 5.0 {
+		if value != 5.0 {
 			t.Errorf("stack not identical to old revision:\n+++  got: %f\n--- want: %f",
-				a, 5.0)
+				value, 5.0)
 		}
 	})
 }
 
 func TestReverse(t *testing.T) {
 	t.Run("reverse", func(t *testing.T) {
-		s := NewStack()
+		stack := NewStack()
 		list := []float64{2, 4, 6}
 		reverse := []float64{6, 4, 2}
 
 		for _, item := range list {
-			s.Push(item)
+			stack.Push(item)
 		}
 
-		s.Reverse()
+		stack.Reverse()
 
-		got := s.All()
+		got := stack.All()
 
 		if len(got) != len(list) {
 			t.Errorf("all failed:\n+++  got: %d elements\n--- want: %d elements",

t/cmdline-command.txtar

@@ -0,0 +1,2 @@
+exec testrpn 1 2 dump
+stdout 'Stack revision 2 .0x'

t/cmdline-invalidcommand.txtar

@@ -0,0 +1,2 @@
+! exec testrpn 1 2 dumb
+stdout 'unknown command or operator'

t/cmdline-precision.txtar

@@ -0,0 +1,2 @@
+exec testrpn -p 4 2 3 /
+stdout '0.6667\n'

t/cmdline-short-stack.txtar

@@ -0,0 +1,2 @@
+! exec testrpn 4 +
+stdout 'stack doesn''t provide enough arguments'

t/cmdlinecalc-debug.txtar

@@ -0,0 +1,2 @@
+exec testrpn -d 44 55 *
+stdout 'push to stack: 2420.00\n'

t/cmdlinecalc-divzero.txtar

@@ -0,0 +1,2 @@
+! exec testrpn 100 50 50 - /
+stdout 'division by null'

t/cmdlinecalc-lua.txtar

@@ -0,0 +1,16 @@
+exec testrpn -d -c test.lua 3 5 lower
+stdout '3\n'
+
+-- test.lua --
+function lower(a,b)
+    if a < b then
+        return a
+    else
+        return b
+    end
+end
+
+function init()
+    -- expects 2 args
+    register("lower", 2, "lower")
+end

t/cmdlinecalc-time.txtar

@@ -0,0 +1,2 @@
+exec testrpn 09:55 4:15 -
+stdout '5.67\n'

t/cmdlinecalc.txtar

@@ -0,0 +1,2 @@
+exec testrpn 44 55 *
+stdout '2420\n'

t/getman.txtar

@@ -0,0 +1,2 @@
+exec testrpn -m
+stdout 'This software is licensed under the GNU GENERAL PUBLIC LICENSE'

t/getusage.txtar

@@ -0,0 +1,2 @@
+exec testrpn -h
+stdout 'This is rpn'

t/getversion.txtar

@@ -0,0 +1,2 @@
+exec testrpn -v
+stdout 'This is rpn version'

t/stdin-batch-cmd.txtar

@@ -0,0 +1,4 @@
+exec echo 1 2 3 4 5 batch median
+stdin stdout
+exec testrpn
+[unix] stdout '3\n'

t/stdin-batch.txtar

@@ -0,0 +1,4 @@
+exec echo 1 2 3 4 5
+stdin stdout
+[unix] exec testrpn median
+[unix] stdout '3\n'

t/stdin-calc.txtar

@@ -0,0 +1,4 @@
+exec echo 10 10 +
+stdin stdout
+exec testrpn
+[unix] stdout '20\n'

t/stdin-help.txtar

@@ -0,0 +1,6 @@
+stdin input.txt
+exec testrpn
+[unix] stdout 'Available configuration commands'
+
+-- input.txt --
+?

t/stdin-use-vars.txtar

@@ -0,0 +1,13 @@
+stdin input.txt
+exec testrpn
+[unix] stdout '28\n'
+
+-- input.txt --
+10
+10
++
+>SUM
+clear
+8
+<SUM
++

t/stdint-explicit-batch.txtar

@@ -0,0 +1,4 @@
+exec echo 1 2 3 4 5 median
+stdin stdout
+exec testrpn -b
+[unix] stdout '3\n'

t/test.lua

@@ -0,0 +1,13 @@
+-- simple function, return the lower number of the two operands
+function lower(a,b)
+    if a < b then
+        return a
+    else
+        return b
+    end
+end
+
+function init()
+    -- expects 2 args
+    register("lower", 2, "lower")
+end  

util.go

@@ -23,13 +23,23 @@ import (
 	"strings"
 )
 
-// find an item in a list
+// find an item in a list, generic variant
-func contains(s []string, e string) bool {
+func contains[E comparable](s []E, v E) bool {
-	for _, a := range s {
+	for _, vs := range s {
-		if a == e {
+		if v == vs {
 			return true
 		}
 	}
+
+	return false
+}
+
+// look if a key in a map exists, generic variant
+func exists[K comparable, V any](m map[K]V, v K) bool {
+	if _, ok := m[v]; ok {
+		return true
+	}
+
 	return false
 }
 
@@ -63,3 +73,7 @@ func const2num(name string) float64 {
 func list2str(list Numbers) string {
 	return strings.Trim(strings.Join(strings.Fields(fmt.Sprint(list)), " "), "[]")
 }
+
+func Error(m string) error {
+	return fmt.Errorf("Error: %s", m)
+}