Adding server for code generation

server/app.yaml

@@ -0,0 +1,27 @@
+# Copyright 2015 Google Inc. All rights reserved.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# http:#www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to writing, software distributed
+# under the License is distributed on a "AS IS" BASIS, WITHOUT WARRANTIES OR
+# CONDITIONS OF ANY KIND, either express or implied.
+
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+version: gae
+runtime: go
+api_version: go1
+
+handlers:
+- url: /generate
+  script: _go_app
+
+- url: /
+  static_files: static/home.html
+  upload: static/home.html
+
+- url: /
+  static_dir: static

server/main.go

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+// +build !appengine
+
+package main
+
+import (
+	"flag"
+	"net/http"
+)
+
+func main() {
+	port := flag.String("http", "127.0.0.1:8080", "ip and port to listen to")
+	flag.Parse()
+	http.HandleFunc("/", homeHandler)
+	http.ListenAndServe(*port, nil)
+}
+
+func homeHandler(w http.ResponseWriter, r *http.Request) {
+	http.ServeFile(w, r, "static/home.html")
+}

server/server.go

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+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Server is an http server that provides an alternative way of generating code
+// based on int types and the constants defined with it.
+//
+// Use the http flag to change the address on which the server will listen for
+// requests. The default is 127.0.0.1:8080.
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"path/filepath"
+	"text/template"
+
+	"go/format"
+
+	"github.com/campoy/jsonenums/parser"
+)
+
+func init() {
+	http.Handle("/generate", handler(generateHandler))
+}
+
+func generateHandler(w http.ResponseWriter, r *http.Request) error {
+	if r.Method != "GET" {
+		return codeError{fmt.Errorf("only GET accepted"), http.StatusMethodNotAllowed}
+	}
+	code := r.FormValue("code")
+	if code == "" {
+		return codeError{fmt.Errorf("no code to be parsed"), http.StatusBadRequest}
+	}
+	typ := r.FormValue("type")
+	if typ == "" {
+		return codeError{fmt.Errorf("no type to be analyzed"), http.StatusBadRequest}
+	}
+
+	dir, err := createDir(code)
+	if err != nil {
+		return err
+	}
+	defer os.RemoveAll(dir)
+
+	pkg, err := parser.ParsePackage(dir, "")
+	if err != nil {
+		return fmt.Errorf("parse package: %v", err)
+	}
+
+	values, err := pkg.ValuesOfType(typ)
+	if err != nil {
+		return fmt.Errorf("find values: %v", err)
+	}
+
+	t, err := template.New("code").Parse(r.FormValue("template"))
+	if err != nil {
+		return codeError{fmt.Errorf("parse template: %v", err), http.StatusBadRequest}
+	}
+	var data = struct {
+		PackageName string
+		TypeName    string
+		Values      []string
+	}{pkg.Name, typ, values}
+
+	var buf bytes.Buffer
+	if err := t.Execute(&buf, data); err != nil {
+		return codeError{fmt.Errorf("execute template: %v", err), http.StatusBadRequest}
+	}
+	src, err := format.Source(buf.Bytes())
+	if err != nil {
+		return codeError{fmt.Errorf("code generated is not valid: %v\n%v", err, buf.String()), http.StatusBadRequest}
+	}
+	w.Write(src)
+	return nil
+}
+
+func createDir(content string) (string, error) {
+	dir, err := ioutil.TempDir("", "jsonenums")
+	if err != nil {
+		return "", fmt.Errorf("create tmp dir: %v", err)
+	}
+	f, err := os.Create(filepath.Join(dir, "main.go"))
+	if err != nil {
+		os.RemoveAll(dir)
+		return "", fmt.Errorf("create tmp file: %v", err)
+	}
+	f.WriteString(content)
+	f.Close()
+	return dir, err
+}
+
+type handler func(http.ResponseWriter, *http.Request) error
+
+func (h handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	err := h(w, r)
+	if err != nil {
+		code := http.StatusInternalServerError
+		if cErr, ok := err.(codeError); ok {
+			code = cErr.code
+		} else {
+			log.Printf("%v: %v", r.URL, code)
+		}
+		http.Error(w, err.Error(), code)
+	}
+}
+
+type codeError struct {
+	error
+	code int
+}

server/static/home.html

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+<html>
+<title>jsonenums</title>
+<style>
+    textarea,
+    input {
+        display: block;
+        width: 80%;
+        margin: auto;
+    }
+    textarea {
+        height: 200px;
+        overflow-y: scroll;
+    }
+</style>
+
+<script src="https://code.jquery.com/jquery-2.1.3.min.js"></script>
+<script>
+    function generate() {
+        $.get("/generate", {
+            "code": $("#code").val(),
+            "type": $("#type").val(),
+            "template": $("#template").val(),
+        }).done(function(res) {
+            $("#result").val(res);
+            $("#result").css('background','#fff');
+        }).fail(function(res) {
+            $("#result").val(res.responseText);
+            $("#result").css('background','#fee');
+        })
+    }
+</script>
+
+<body>
+
+    <form action="/generate" method="GET">
+        <input type="text" id="type" value="WeekDay">
+        <textarea id="code">
+package test
+
+type WeekDay int
+
+const (
+    Monday WeekDay = iota
+    Tuesday
+    Wednesday
+    Thursday
+    Friday
+    Saturday
+    Sunday
+)
+        </textarea>
+        <textarea id="template">
+package {{.PackageName}}
+
+func (r {{.TypeName}}) String() string {
+    s, ok := map[{{.TypeName}}]string {
+        {{range .Values}}{{.}}:"{{.}}",{{end}}
+    }
+    if !ok {
+        return "unknown {{.TypeName}}"
+    }
+    return s
+}
+        </textarea>
+    </form>
+
+    <input type="button" onclick="generate()" value="generate code">
+
+    <textarea id="result">
+    </textarea>
+</body>
+
+</html>