Factor REPL into CLI part and agnostic part and add tests

This is to facilitate reuse of the REPL. It also makes testing possible.

Author: ncw

main.go

@@ -12,7 +12,8 @@ import (
 "runtime/pprof"
 
  _ "github.com/go-python/gpython/builtin"
-"github.com/go-python/gpython/repl"
+"github.com/go-python/gpython/repl/cli"
+
 //_ "github.com/go-python/gpython/importlib"
 "io/ioutil"
 "log"
@@ -62,7 +63,7 @@ func main(){
 args:=flag.Args()
 py.MustGetModule("sys").Globals["argv"] =pysys.MakeArgv(args)
 iflen(args) ==0{
-repl.Run()
+cli.RunREPL()
 return
  }
 prog:=args[0]

repl/cli/cli.go

@@ -0,0 +1,149 @@
+// Copyright 2018 The go-python Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Read Eval Print Loop for CLI
+package cli
+
+import (
+"fmt"
+"io"
+"os"
+"os/user"
+"path/filepath"
+
+"github.com/go-python/gpython/py"
+"github.com/go-python/gpython/repl"
+"github.com/peterh/liner"
+)
+
+constHistoryFileName=".gpyhistory"
+
+// homeDirectory finds the home directory or returns ""
+funchomeDirectory() string{
+usr, err:=user.Current()
+iferr==nil{
+returnusr.HomeDir
+ }
+// Fall back to reading $HOME - work around user.Current() not
+// working for cross compiled binaries on OSX.
+// https://github.com/golang/go/issues/6376
+returnos.Getenv("HOME")
+}
+
+// Holds state for readline services
+typereadlinestruct{
+*liner.State
+repl*repl.REPL
+historyFilestring
+module*py.Module
+promptstring
+}
+
+// newReadline creates a new instance of readline
+funcnewReadline(repl*repl.REPL) *readline{
+rl:=&readline{
+State: liner.NewLiner(),
+repl: repl,
+ }
+home:=homeDirectory()
+ifhome!=""{
+rl.historyFile=filepath.Join(home, HistoryFileName)
+ }
+rl.SetTabCompletionStyle(liner.TabPrints)
+rl.SetWordCompleter(rl.Completer)
+returnrl
+}
+
+// readHistory reads the history into the term
+func (rl*readline) ReadHistory() error{
+f, err:=os.Open(rl.historyFile)
+iferr!=nil{
+returnerr
+ }
+deferf.Close()
+_, err=rl.State.ReadHistory(f)
+iferr!=nil{
+returnerr
+ }
+returnnil
+}
+
+// writeHistory writes the history from the term
+func (rl*readline) WriteHistory() error{
+f, err:=os.OpenFile(rl.historyFile, os.O_RDWR|os.O_APPEND|os.O_CREATE, 0666)
+iferr!=nil{
+returnerr
+ }
+deferf.Close()
+_, err=rl.State.WriteHistory(f)
+iferr!=nil{
+returnerr
+ }
+returnnil
+}
+
+// Close the readline and write history
+func (rl*readline) Close() error{
+err:=rl.State.Close()
+iferr!=nil{
+returnerr
+ }
+ifrl.historyFile!=""{
+err:=rl.WriteHistory()
+iferr!=nil{
+returnerr
+ }
+ }
+returnnil
+}
+
+// Completer 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!!!".
+func (rl*readline) Completer(linestring, posint) (headstring, completions []string, tailstring){
+returnrl.repl.Completer(line, pos)
+}
+
+// SetPrompt sets the current terminal prompt
+func (rl*readline) SetPrompt(promptstring){
+rl.prompt=prompt
+}
+
+// Print prints the output
+func (rl*readline) Print(outstring){
+_, _=os.Stdout.WriteString(out+"\n")
+}
+
+// RunREPL starts the REPL loop
+funcRunREPL(){
+repl:=repl.New()
+rl:=newReadline(repl)
+repl.SetUI(rl)
+deferrl.Close()
+err:=rl.ReadHistory()
+iferr!=nil{
+fmt.Printf("Failed to open history: %v\n", err)
+ }
+
+fmt.Printf("Gpython 3.4.0\n")
+
+for{
+line, err:=rl.Prompt(rl.prompt)
+iferr!=nil{
+iferr==io.EOF{
+fmt.Printf("\n")
+break
+ }
+fmt.Printf("Problem reading line: %v\n", err)
+continue
+ }
+ifline!=""{
+rl.AppendHistory(line)
+ }
+rl.repl.Run(line)
+ }
+}