Implement go fmt functionality (fix #16)

README.md

@@ -84,6 +84,7 @@ If you are using Linux or Mac OS, you can use start/stop scripts instead. Web br
 - Run `jupyter notebook` command to start Juyputer Notebook and select "Go (lgo)" from New Notebook menu.
 - To show documents of packages, functions and variables in your code, move the cursor to the identifier you want to inspect and press `Shift-Tab`.
 - Press `Tab` to complete code
+- Click `Format Go` button in the toolbar to format code.
 - lgo works with [JupyterLab](https://github.com/jupyterlab/jupyterlab). To use lgo from JupyterLab, install JupyterLab and run `jupyter lab`.
 
 <img width="400" height="225" src="doc/inspect.jpg">
@@ -195,25 +196,25 @@ gore is a CLI tool and it does not support Jupyter Notebook.
 |Backend|gc (go compiler)|An unofficial interpreter|
 |Full Go Language Specs|:heavy_check_mark:||
 |100% gc compatible|:heavy_check_mark:||
-|Type Safety|:heavy_check_mark:||
+|Static typing|:heavy_check_mark:|to some extent|
 |Performance|Fast|Slow|
 |Overhead|500ms|1ms|
 |[Cancellation](https://github.com/yunabe/lgo/blob/master/README.md#cancellation)|:heavy_check_mark:||
 |Code completion|:heavy_check_mark:||
 |Code inspection|:heavy_check_mark:||
+|Code formatting|:heavy_check_mark:||
 |[Display HTML and images](https://github.com/yunabe/lgo/blob/master/README.md#display-html-and-images)|:heavy_check_mark:||
 |Windows, Mac|Use Docker or VM|Partial|
 |License|BSD|LGPL|
 
-[gophernotes](https://github.com/gopherdata/gophernotes) is the first Jupyter kernel for Go, released in Jan 2016.
+gophernotes was the first Jupyter kernel for Go, released in Jan 2016.
 Before [Sep 2017](https://github.com/gopherdata/gophernotes/commit/69792d8af799d6905e2c576164d1a189ac021784#diff-04c6e90faac2675aa89e2176d2eec7d8), it used the same technology gore uses to evaluate Go code. This means it did not fit to heavy data processing or data analysis at all.
-From Sep 2017, gophernotes switched from `go run` approach to [gomacro](https://github.com/cosmos72/gomacro), one of unofficial golang interpreters by [cosmos72](https://github.com/cosmos72). This solved the problem gore has. Now, gophernotes is a great tool for data science in Go.
+From Sep 2017, gophernotes switched from `go run` approach to [gomacro](https://github.com/cosmos72/gomacro), one of unofficial golang interpreters by [cosmos72](https://github.com/cosmos72). This solved the problem gore has. Now, the code execution mechnism of gophernotes also fits to heavy data analysis.
 
 The shortcomings of using an unofficial interpreter are
 - It does not support all Go language features. Especially, it does not support one of the most important Go feature, `interface`.
   As of go1.10, it is hard to support `interface` in an interpreter written in Go because of the lack of API in `reflect` package.
 - Interpreters are generally slow.
-- Type unsafe. At least, gomacro is not statically typed.
 - Unofficial interpreters are not well-tested compared to the official gc (go compiler) tools.
 
 The advantages of this approach are

bin/install_kernel

@@ -8,6 +8,7 @@ from __future__ import print_function
 import argparse
 import json
 import os
+import shutil
 import sys
 
 from jupyter_client.kernelspec import KernelSpecManager
@@ -29,7 +30,12 @@ def install_kernel_spec(binary, user, prefix):
         os.chmod(td, 0o755) # Starts off as 700, not user readable
         with open(os.path.join(td, 'kernel.json'), 'w') as f:
             json.dump(kernel_json, f, sort_keys=True)
-        # TODO: Copy any resources
+
+        resources = os.path.join(os.path.dirname(__file__), 'kernel_resources')
+        for item in os.listdir(resources):
+            src = os.path.join(resources, item)
+            if not os.path.isdir(src):
+                shutil.copy(src, os.path.join(td, item))
 
         print('Installing Jupyter kernel spec')
         KernelSpecManager().install_kernel_spec(td, 'lgo', user=user, replace=True, prefix=prefix)

bin/kernel_resources/kernel.js

@@ -0,0 +1,37 @@
+// Kernel specific extension for lgo.
+// http://jupyter-notebook.readthedocs.io/en/stable/extending/frontend_extensions.html#kernel-specific-extensions
+
+define(function(){
+  var formatCells = function () {
+    var cells = Jupyter.notebook.get_selected_cells();
+    for (var i = 0; i < cells.length; i++) {
+      (function(){
+        var editor = cells[i].code_mirror;
+        var msg = {code: editor.getValue()};
+        var cb = function(msg) {
+          if (!msg || !msg.content || msg.content.status != 'ok') {
+            // TODO: Show an error message.
+            return;
+          }
+          editor.setValue(msg.content.code);
+        };
+        Jupyter.notebook.kernel.send_shell_message("gofmt_request", msg, {shell: {reply: cb}});
+      })();
+    }
+  };
+
+  var action = {
+    icon: 'fa-align-left', // a font-awesome class used on buttons, etc
+    help    : 'Format Go',
+    handler : formatCells
+  };
+  var prefix = 'lgo-kernel';
+  var actionName = 'format-code';
+
+  var fullActionName = Jupyter.actions.register(action, actionName, prefix);
+  Jupyter.toolbar.add_buttons_group([fullActionName]);
+
+  return {
+    onload: function(){}
+  }
+});

cmd/lgo-internal/kernel.go

@@ -17,6 +17,7 @@ import (
 	"github.com/yunabe/lgo/cmd/lgo-internal/liner"
 	"github.com/yunabe/lgo/cmd/runner"
 	"github.com/yunabe/lgo/core"
+	"github.com/yunabe/lgo/converter"
 	scaffold "github.com/yunabe/lgo/jupyter/gojupyterscaffold"
 )
 
@@ -242,6 +243,17 @@ func (*handlers) HandleIsComplete(req *scaffold.IsCompleteRequest) *scaffold.IsC
 	}
 }
 
+func (*handlers) HandleGoFmt(req *scaffold.GoFmtRequest) (*scaffold.GoFmtReply, error) {
+	formatted, err := converter.Format(req.Code)
+	if err != nil {
+		return nil, err
+	}
+	return &scaffold.GoFmtReply{
+		Status: "ok",
+		Code: formatted,
+	}, nil
+}
+
 // kernelLogWriter forwards messages to the current os.Stderr, which is change on every execution.
 type kernelLogWriter struct{}
 

jupyter/gojupyterscaffold-example/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"errors"
 	"flag"
 	"fmt"
 	"html"
@@ -99,6 +100,10 @@ func (*handlers) HandleIsComplete(req *scaffold.IsCompleteRequest) *scaffold.IsC
 	return nil
 }
 
+func (*handlers) HandleGoFmt(req *scaffold.GoFmtRequest) (*scaffold.GoFmtReply, error) {
+	return nil, errors.New("not implemented")
+}
+
 func main() {
 	flag.Parse()
 	fmt.Printf("os.Args == %+v\n", os.Args)

jupyter/gojupyterscaffold/api.go

@@ -15,6 +15,7 @@ type RequestHandlers interface {
 	HandleInspect(req *InspectRequest) *InspectReply
 	// http://jupyter-client.readthedocs.io/en/latest/messaging.html#code-completeness
 	HandleIsComplete(req *IsCompleteRequest) *IsCompleteReply
+	HandleGoFmt(req *GoFmtRequest) (*GoFmtReply, error)
 }
 
 type KernelInfo struct {
@@ -40,6 +41,13 @@ type ExecuteRequest struct {
 	StopOnError  bool   `json:"stop_on_error"`
 }
 
+// See http://jupyter-client.readthedocs.io/en/stable/messaging.html#request-reply
+type errorReply struct {
+	Status string `json:"status"` // status must be always "error"
+	Ename  string `json:"ename,omitempty"`
+	Evalue string `json:"evalue,omitempty"`
+}
+
 // See http://jupyter-client.readthedocs.io/en/latest/messaging.html#introspection
 type InspectRequest struct {
 	Code      string `json:"code"`
@@ -130,3 +138,12 @@ type IsCompleteReply struct {
 	// field does not exist.
 	Indent string `json:"indent"`
 }
+
+type GoFmtRequest struct {
+	Code string `json:"code"`
+}
+
+type GoFmtReply struct {
+	Status string `json:"status"`
+	Code   string `json:"code"`
+}

jupyter/gojupyterscaffold/message.go

@@ -45,6 +45,8 @@ func newContentForMsgType(header *messageHeader) interface{} {
 		return &InspectRequest{}
 	case "is_complete_request":
 		return &IsCompleteRequest{}
+	case "gofmt_request":
+		return &GoFmtRequest{}
 	}
 	return nil
 }

jupyter/gojupyterscaffold/shelsocket.go

@@ -319,6 +319,7 @@ func (s *shellSocket) handleMessages() error {
 	if err != nil {
 		return fmt.Errorf("Failed to unmarshal messages from %s: %v", s.name, err)
 	}
+	glog.Warningf("MsgType in %s: %q", s.name, msg.Header.MsgType)
 	switch typ := msg.Header.MsgType; typ {
 	case "kernel_info_request":
 		if err := s.sendKernelInfo(&msg); err != nil {
@@ -373,6 +374,22 @@ func (s *shellSocket) handleMessages() error {
 			res.Content = reply
 			s.pushResult(res)
 		}()
+	case "gofmt_request":
+		go func() {
+			res := newMessageWithParent(&msg)
+			res.Header.MsgType = "gofmt_reply"
+			reply, err := s.handlers.HandleGoFmt(msg.Content.(*GoFmtRequest))
+			if err != nil {
+				res.Content = &errorReply{
+					Status: "error",
+					Ename:  "error",
+					Evalue: err.Error(),
+				}
+			} else {
+				res.Content = reply
+			}
+			s.pushResult(res)
+		}()
 	default:
 		glog.Warningf("Unsupported MsgType in %s: %q", s.name, typ)
 	}