cmd, console: split off the console into a reusable package

1 files changed, 156 insertions, 0 deletions

diff --git a/console/prompter.go b/console/prompter.go
new file mode 100644
index 000000000..5039e8b1c
--- /dev/null
+++ b/console/prompter.go
@@ -0,0 +1,156 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package console
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/peterh/liner"
+)
+
+// TerminalPrompter holds the stdin line reader (also using stdout for printing
+// prompts). Only this reader may be used for input because it keeps an internal
+// buffer.
+var TerminalPrompter = newTerminalPrompter()
+
+// UserPrompter defines the methods needed by the console to promt the user for
+// various types of inputs.
+type UserPrompter interface {
+	// PromptInput displays the given prompt to the user and requests some textual
+	// data to be entered, returning the input of the user.
+	PromptInput(prompt string) (string, error)
+
+	// PromptPassword displays the given prompt to the user and requests some textual
+	// data to be entered, but one which must not be echoed out into the terminal.
+	// The method returns the input provided by the user.
+	PromptPassword(prompt string) (string, error)
+
+	// PromptConfirm displays the given prompt to the user and requests a boolean
+	// choice to be made, returning that choice.
+	PromptConfirm(prompt string) (bool, error)
+
+	// SetScrollHistory sets the the input scrollback history that the prompter will
+	// allow the user to scoll back to.
+	SetScrollHistory(history []string)
+
+	// SetWordCompleter sets the completion function that the prompter will call to
+	// fetch completion candidates when the user presses tab.
+	SetWordCompleter(completer WordCompleter)
+}
+
+// WordCompleter takes the currently edited line with the cursor position and
+// returns the completion candidates for the partial word to be completed. If
+// the line is "Hello, wo!!!" and the cursor is before the first '!', ("Hello,
+// wo!!!", 9) is passed to the completer which may returns ("Hello, ", {"world",
+// "Word"}, "!!!") to have "Hello, world!!!".
+type WordCompleter func(line string, pos int) (string, []string, string)
+
+// terminalPrompter is a UserPrompter backed by the liner package. It supports
+// prompting the user for various input, among others for non-echoing password
+// input.
+type terminalPrompter struct {
+	*liner.State
+	warned     bool
+	supported  bool
+	normalMode liner.ModeApplier
+	rawMode    liner.ModeApplier
+}
+
+// newTerminalPrompter creates a liner based user input prompter working off the
+// standard input and output streams.
+func newTerminalPrompter() *terminalPrompter {
+	r := new(terminalPrompter)
+	// Get the original mode before calling NewLiner.
+	// This is usually regular "cooked" mode where characters echo.
+	normalMode, _ := liner.TerminalMode()
+	// Turn on liner. It switches to raw mode.
+	r.State = liner.NewLiner()
+	rawMode, err := liner.TerminalMode()
+	if err != nil || !liner.TerminalSupported() {
+		r.supported = false
+	} else {
+		r.supported = true
+		r.normalMode = normalMode
+		r.rawMode = rawMode
+		// Switch back to normal mode while we're not prompting.
+		normalMode.ApplyMode()
+	}
+	r.SetCtrlCAborts(true)
+	r.SetTabCompletionStyle(liner.TabPrints)
+
+	return r
+}
+
+// PromptInput displays the given prompt to the user and requests some textual
+// data to be entered, returning the input of the user.
+func (r *terminalPrompter) PromptInput(prompt string) (string, error) {
+	if r.supported {
+		r.rawMode.ApplyMode()
+		defer r.normalMode.ApplyMode()
+	} else {
+		// liner tries to be smart about printing the prompt
+		// and doesn't print anything if input is redirected.
+		// Un-smart it by printing the prompt always.
+		fmt.Print(prompt)
+		prompt = ""
+		defer fmt.Println()
+	}
+	return r.State.Prompt(prompt)
+}
+
+// PromptPassword displays the given prompt to the user and requests some textual
+// data to be entered, but one which must not be echoed out into the terminal.
+// The method returns the input provided by the user.
+func (r *terminalPrompter) PromptPassword(prompt string) (passwd string, err error) {
+	if r.supported {
+		r.rawMode.ApplyMode()
+		defer r.normalMode.ApplyMode()
+		return r.State.PasswordPrompt(prompt)
+	}
+	if !r.warned {
+		fmt.Println("!! Unsupported terminal, password will be echoed.")
+		r.warned = true
+	}
+	// Just as in Prompt, handle printing the prompt here instead of relying on liner.
+	fmt.Print(prompt)
+	passwd, err = r.State.Prompt("")
+	fmt.Println()
+	return passwd, err
+}
+
+// PromptConfirm displays the given prompt to the user and requests a boolean
+// choice to be made, returning that choice.
+func (r *terminalPrompter) PromptConfirm(prompt string) (bool, error) {
+	input, err := r.Prompt(prompt + " [y/N] ")
+	if len(input) > 0 && strings.ToUpper(input[:1]) == "Y" {
+		return true, nil
+	}
+	return false, err
+}
+
+// SetScrollHistory sets the the input scrollback history that the prompter will
+// allow the user to scoll back to.
+func (r *terminalPrompter) SetScrollHistory(history []string) {
+	r.State.ReadHistory(strings.NewReader(strings.Join(history, "\n")))
+}
+
+// SetWordCompleter sets the completion function that the prompter will call to
+// fetch completion candidates when the user presses tab.
+func (r *terminalPrompter) SetWordCompleter(completer WordCompleter) {
+	r.State.SetWordCompleter(liner.WordCompleter(completer))
+}