NewTemplateFileSystem for fileb0x (similar to vfsgen, assetfs, etc)

[coolaj86]

I needed to use macaron.Render with fileb0x instead of bindata. I think that this code will be helpful for anyone who might need to use vfsgen, packr, statik, rice and other bindata-style systems.

package router

import (
	"bytes"
	"fmt"
	"io"
	"path/filepath"

	"code.example.com/me/go-static"

	"gopkg.in/macaron.v1"
)

// Replace the one from macaron.Render since the files field is private
// TplFileSystem implements TemplateFileSystem interface.
type TplFileSystem struct {
	files []macaron.TemplateFile
}

// NewTemplateFileSystem creates new template file system with given options.
func NewTemplateFileSystem(lastDir string, exts ...string) macaron.TemplateFileSystem {
	fs := TplFileSystem{}
	fs.files = make([]macaron.TemplateFile, 0, 10)
	if 0 == len(exts) {
		exts = []string{".tmpl", ".html"}
	}

	// This is the fileb0x WalkDirs
	paths, _ := static.WalkDirs(lastDir, false)
	for _, path := range paths {
		r, err := filepath.Rel(lastDir, path)
		ext := macaron.GetExt(r)

		for _, extension := range exts {
			if ext != extension {
				continue
			}

			var data []byte
			// Loop over candidates of directory, break out once found.
			// The file always exists because it's inside the walk function,
			// and read original file is the worst case.
			path = filepath.Join(lastDir, r)
			data, err = static.ReadFile(path)
			if err != nil {
				panic(err)
			}

			name := filepath.ToSlash((r[0 : len(r)-len(ext)]))
			fs.files = append(fs.files, macaron.NewTplFile(name, data, ext))
		}
	}

	return fs
}

func (fs TplFileSystem) ListFiles() []macaron.TemplateFile {
	return fs.files
}

func (fs TplFileSystem) Get(name string) (io.Reader, error) {
	for i := range fs.files {
		if fs.files[i].Name()+fs.files[i].Ext() == name {
			return bytes.NewReader(fs.files[i].Data()), nil
		}
	}
	return nil, fmt.Errorf("file '%s' not found", name)
}

This could probably be updated to use a generic interface that would work with many different FileSystem implementations and be created as a PR. However, for now I'll just leave this an example that others can easily follow.