Initial commit. First pass.

.gitignore

@@ -0,0 +1 @@
+.DS_Store

example/main.go

@@ -0,0 +1,66 @@
+package main
+
+import (
+	"fmt"
+	"tea"
+)
+
+type Model int
+
+func main() {
+	p := tea.NewProgram(0, update, view)
+	p.Start()
+}
+
+func update(msg tea.Msg, model tea.Model) (tea.Model, tea.Cmd) {
+	m, _ := model.(Model)
+
+	switch msg := msg.(type) {
+	case tea.KeyPressMsg:
+		switch msg {
+
+		case "j":
+			m += 1
+			if m > 3 {
+				m = 3
+			}
+
+		case "k":
+			m -= 1
+			if m < 0 {
+				m = 0
+			}
+
+		case "q":
+			return m, tea.Quit
+
+		}
+	}
+
+	return m, nil
+}
+
+func view(model tea.Model) string {
+	m, _ := model.(Model)
+
+	choices := fmt.Sprintf(
+		"%s\n%s\n%s\n%s",
+		checkbox("Plant carrots", m == 0),
+		checkbox("Go to the market", m == 1),
+		checkbox("Read something", m == 2),
+		checkbox("See friends", m == 3),
+	)
+
+	return fmt.Sprintf(
+		"What to do today?\n\n%s.\n\n(press j/k to select or q to quit)",
+		choices,
+	)
+}
+
+func checkbox(label string, checked bool) string {
+	check := " "
+	if checked {
+		check = "x"
+	}
+	return fmt.Sprintf("[%s] %s", check, label)
+}

go.mod

@@ -0,0 +1,8 @@
+module tea
+
+go 1.13
+
+require (
+	github.com/pkg/term v0.0.0-20190109203006-aa71e9d9e942
+	github.com/tj/go-terminput v1.0.0
+)

go.sum

@@ -0,0 +1,13 @@
+github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1/go.mod h1:wJfORRmW1u3UXTncJ5qlYoELFm8eSnnEO6hX4iZ3EWY=
+github.com/jtolds/gls v4.20.0+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfVYBRgL+9YlvaHOwJU=
+github.com/pkg/term v0.0.0-20190109203006-aa71e9d9e942 h1:A7GG7zcGjl3jqAqGPmcNjd/D9hzL95SuoOQAaFNdLU0=
+github.com/pkg/term v0.0.0-20190109203006-aa71e9d9e942/go.mod h1:eCbImbZ95eXtAUIbLAuAVnBnwf83mjf6QIVH8SHYwqQ=
+github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d/go.mod h1:OnSkiWE9lh6wB0YB77sQom3nweQdgAjqCqsofrRNTgc=
+github.com/smartystreets/goconvey v0.0.0-20190731233626-505e41936337/go.mod h1:syvi0/a8iFYH4r/RixwvyeAJjdLS9QV7WQ/tjFTllLA=
+github.com/tj/go-terminput v1.0.0 h1:X928u7ohxr7Dfzlxppvc5Zql5Lwd1bOH5VyIL2RPrFw=
+github.com/tj/go-terminput v1.0.0/go.mod h1:8zzAs+cqdjZlTxE9DbGyjKDfGNxaJjC5bvg4vkWX2V0=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/tools v0.0.0-20190328211700-ab21143f2384/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=

key.go

@@ -0,0 +1,32 @@
+package tea
+
+import (
+	"errors"
+	"io"
+	"unicode/utf8"
+)
+
+// KeyPressMsg contains information about a keypress
+type KeyPressMsg string
+
+// ReadKey reads keypress input from a TTY and returns a string representation
+// of a key
+func ReadKey(r io.Reader) (string, error) {
+	var buf [256]byte
+
+	// Read and block
+	_, err := r.Read(buf[:])
+	if err != nil {
+		return "", err
+	}
+
+	// TODO: non-rune keys like arrows, meta keys, and so on
+
+	// Read "normal" key
+	c, _ := utf8.DecodeRune(buf[:])
+	if c == utf8.RuneError {
+		return "", errors.New("no such rune")
+	}
+
+	return string(c), nil
+}

tea.go

@@ -0,0 +1,168 @@
+package tea
+
+import (
+	"fmt"
+	"io"
+	"strings"
+
+	"github.com/pkg/term"
+)
+
+// Escape sequence
+const esc = "\033["
+
+// Msg represents an action. It's used by Update to update the UI.
+type Msg interface{}
+
+// Model contains the data for an application
+type Model interface{}
+
+// Cmd is an IO operation. If it's nil it's considered a no-op.
+type Cmd func() Msg
+
+// Update is called when a message is received. It may update the model and/or
+// send a command.
+type Update func(Msg, Model) (Model, Cmd)
+
+// View produces a string which will be rendered to the terminal
+type View func(Model) string
+
+// Program is a terminal user interface
+type Program struct {
+	model  Model
+	update Update
+	view   View
+	rw     io.ReadWriter
+}
+
+// Quit command
+func Quit() Msg {
+	return quitMsg{}
+}
+
+// Signals that the program should quit
+type quitMsg struct{}
+
+// NewProgram creates a new Program
+func NewProgram(model Model, update Update, view View) *Program {
+	return &Program{
+		model:  model,
+		update: update,
+		view:   view,
+		// TODO: subscriptions
+	}
+}
+
+// Start initializes the program
+// TODO: error channel
+func (p *Program) Start() error {
+	var (
+		model = p.model
+		cmd   Cmd
+		cmds  = make(chan Cmd)
+		msgs  = make(chan Msg)
+		done  = make(chan struct{})
+	)
+
+	tty, err := term.Open("/dev/tty")
+	if err != nil {
+		return err
+	}
+
+	p.rw = tty
+	tty.SetRaw()
+	defer func() {
+		showCursor()
+		tty.Restore()
+	}()
+
+	// Render initial view
+	hideCursor()
+	p.render(model, true)
+
+	// Subscribe to user input
+	// TODO: move to program struct to allow for subscriptions to other things,
+	// too, like timers, frames, download/upload progress and so on.
+	go func() {
+		for {
+			select {
+			default:
+				msg, _ := ReadKey(p.rw)
+				msgs <- KeyPressMsg(msg)
+			}
+		}
+	}()
+
+	// Process commands
+	go func() {
+		for {
+			select {
+			case <-done:
+				return
+			case cmd := <-cmds:
+				if cmd != nil {
+					go func() {
+						msgs <- cmd()
+					}()
+				}
+			}
+		}
+	}()
+
+	// Handle updates and draw
+	for {
+		select {
+		case msg := <-msgs:
+			if _, ok := msg.(quitMsg); ok {
+				close(done)
+				return nil
+			}
+
+			model, cmd = p.update(msg, model)
+			cmds <- cmd // process command (if any)
+			p.render(model, false)
+			p.model = model
+		}
+	}
+}
+
+// Render a view
+func (p *Program) render(model Model, init bool) {
+	view := p.view(model)
+
+	// We need to add carriage returns to ensure that the cursor travels to the
+	// start of a column after a newline
+	view = strings.Replace(view, "\n", "\r\n", -1)
+
+	if !init {
+		clearLines(strings.Count(view, "\r\n"))
+	}
+	io.WriteString(p.rw, view)
+}
+
+func hideCursor() {
+	fmt.Printf(esc + "?25l")
+}
+
+func showCursor() {
+	fmt.Printf(esc + "?25h")
+}
+
+func cursorUp(n int) {
+	fmt.Printf(esc+"%dF", n)
+}
+
+func clearLine() {
+	fmt.Printf(esc + "2K")
+}
+
+func clearLines(n int) {
+	for i := 0; i < n; i++ {
+		cursorUp(1)
+		clearLine()
+	}
+}
+
+func clearScreen() {
+	fmt.Printf(esc + "2J" + esc + "3J" + esc + "1;1H")
+}