feat: implement "clear" command

Closes #17

CHANGELOG.md

@@ -4,4 +4,8 @@
 
 - switch from flags to subcommands: `wl-paste -t text --watch clipman store` instead than `clipman -d` and `clipman pick` instead than `clipman -s`
 - switch demon from polling to event-driven: requires wl-clipboard >= 2.0
+
+**New features**:
+
 - primary clipboard support: `wl-paste -p -t text --watch clipman store --histpath="~/.local/share/clipman-primary.json` and `clipman pick --histpath="~/.local/share/clipman-primary.json`
+- new `clear` command for removing item(s) from history

main.go

@@ -7,20 +7,25 @@ import (
 	"io/ioutil"
 	"log"
 	"os"
+	"os/exec"
 	"strings"
 
 	"gopkg.in/alecthomas/kingpin.v2"
 )
 
 var (
-	app       = kingpin.New("clipman", "A clipboard manager for Wayland")
-	histpath  = app.Flag("histpath", "Path of history file").Default("~/.local/share/clipman.json").String()
-	storer    = app.Command("store", "Run from `wl-paste --watch` to record clipboard events")
-	picker    = app.Command("pick", "Pick an item from clipboard history")
-	noPersist = storer.Flag("no-persist", "Don't persist a copy buffer after a program exits").Short('P').Default("false").Bool()
-	maxDemon  = storer.Flag("max-items", "history size").Default("15").Int()
-	maxPicker = picker.Flag("max-items", "scrollview length").Default("15").Int()
-	tool      = picker.Flag("selector", "Which selector to use: dmenu/rofi/-").Default("dmenu").String()
+	app        = kingpin.New("clipman", "A clipboard manager for Wayland")
+	histpath   = app.Flag("histpath", "Path of history file").Default("~/.local/share/clipman.json").String()
+	storer     = app.Command("store", "Run from `wl-paste --watch` to record clipboard events")
+	picker     = app.Command("pick", "Pick an item from clipboard history")
+	clearer    = app.Command("clear", "Remove an item from history")
+	noPersist  = storer.Flag("no-persist", "Don't persist a copy buffer after a program exits").Short('P').Default("false").Bool()
+	maxDemon   = storer.Flag("max-items", "history size").Default("15").Int()
+	maxPicker  = picker.Flag("max-items", "scrollview length").Default("15").Int()
+	pickTool   = picker.Flag("selector", "Which selector to use: dmenu/rofi/-").Default("dmenu").String()
+	clearTool  = clearer.Flag("selector", "Which selector to use: dmenu/rofi/-").Default("dmenu").String()
+	maxClearer = clearer.Flag("max-items", "scrollview length").Default("15").Int()
+	clearAll   = clearer.Flag("all", "Remove all items").Short('a').Default("false").Bool()
 )
 
 func main() {
@@ -52,7 +57,32 @@ func main() {
 			log.Fatal(err)
 		}
 
-		if err := selector(history, *maxPicker, *tool); err != nil {
+		selection, err := selector(history, *maxPicker, *pickTool)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		// serve selection to the OS
+		err = exec.Command("wl-copy", []string{"--", selection}...).Run()
+	case "clear":
+		histfile, history, err := getHistory()
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		if *clearAll {
+			if err := os.Remove(histfile); err != nil {
+				log.Fatal(err)
+			}
+			os.Exit(0)
+		}
+
+		selection, err := selector(history, *maxClearer, *clearTool)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		if err := write(filter(history, selection), histfile); err != nil {
 			log.Fatal(err)
 		}
 	}

selector.go

@@ -9,25 +9,23 @@ import (
 	"strings"
 )
 
-func selector(history []string, max int, tool string) error {
+func selector(history []string, max int, tool string) (string, error) {
 	if len(history) == 0 {
 		log.Fatal("No history available")
 	}
 
+	// don't modify in-place!
+	tmp := make([]string, len(history))
+	copy(tmp, history)
+
 	// reverse the history
 	for i, j := 0, len(history)-1; i < j; i, j = i+1, j-1 {
-		history[i], history[j] = history[j], history[i]
+		tmp[i], tmp[j] = tmp[j], tmp[i]
 	}
 
-	selected, err := dmenu(history, max, tool)
-	if err != nil {
-		return err
-	}
+	selected, err := dmenu(tmp, max, tool)
 
-	// serve selection to the OS
-	err = exec.Command("wl-copy", []string{"--", selected}...).Run()
-
-	return err
+	return selected, err
 }
 
 func dmenu(list []string, max int, tool string) (string, error) {