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package view
import (
"bytes"
"fmt"
"html/template"
"io"
"io/ioutil"
"os"
"path/filepath"
"strings"
"sync"
"time"
)
// HTMLEngine contains the html view engine structure.
type HTMLEngine struct {
// files configuration
directory string
extension string
assetFn func(name string) ([]byte, error) // for embedded, in combination with directory & extension
namesFn func() []string // for embedded, in combination with directory & extension
reload bool // if true, each time the ExecuteWriter is called the templates will be reloaded, each ExecuteWriter waits to be finished before writing to a new one.
// parser configuration
options []string // text options
left string
right string
layout string
rmu sync.RWMutex // locks for layoutFuncs and funcs
layoutFuncs map[string]interface{}
funcs map[string]interface{}
//
middleware func(name string, contents []byte) (string, error)
Templates *template.Template
//
}
var _ Engine = (*HTMLEngine)(nil)
var emptyFuncs = template.FuncMap{
"yield": func() (string, error) {
return "", fmt.Errorf("yield was called, yet no layout defined")
},
"part": func() (string, error) {
return "", fmt.Errorf("block was called, yet no layout defined")
},
"partial": func() (string, error) {
return "", fmt.Errorf("block was called, yet no layout defined")
},
"partial_r": func() (string, error) {
return "", fmt.Errorf("block was called, yet no layout defined")
},
"current": func() (string, error) {
return "", nil
}, "render": func() (string, error) {
return "", nil
},
}
// HTML creates and returns a new html view engine.
// The html engine used like the "html/template" standard go package
// but with a lot of extra features.
func HTML(directory, extension string) *HTMLEngine {
s := &HTMLEngine{
directory: directory,
extension: extension,
assetFn: nil,
namesFn: nil,
reload: false,
left: "{{",
right: "}}",
layout: "",
layoutFuncs: make(map[string]interface{}, 0),
funcs: make(map[string]interface{}, 0),
}
return s
}
// Ext returns the file extension which this view engine is responsible to render.
func (s *HTMLEngine) Ext() string {
return s.extension
}
// Binary optionally, use it when template files are distributed
// inside the app executable (.go generated files).
//
// The assetFn and namesFn can come from the go-bindata library.
func (s *HTMLEngine) Binary(assetFn func(name string) ([]byte, error), namesFn func() []string) *HTMLEngine {
s.assetFn, s.namesFn = assetFn, namesFn
return s
}
// Reload if set to true the templates are reloading on each render,
// use it when you're in development and you're boring of restarting
// the whole app when you edit a template file.
//
// Note that if `true` is passed then only one `View -> ExecuteWriter` will be render each time,
// no concurrent access across clients, use it only on development status.
// It's good to be used side by side with the https://github.com/kataras/rizla reloader for go source files.
func (s *HTMLEngine) Reload(developmentMode bool) *HTMLEngine {
s.reload = developmentMode
return s
}
// Option sets options for the template. Options are described by
// strings, either a simple string or "key=value". There can be at
// most one equals sign in an option string. If the option string
// is unrecognized or otherwise invalid, Option panics.
//
// Known options:
//
// missingkey: Control the behavior during execution if a map is
// indexed with a key that is not present in the map.
// "missingkey=default" or "missingkey=invalid"
// The default behavior: Do nothing and continue execution.
// If printed, the result of the index operation is the string
// "<no value>".
// "missingkey=zero"
// The operation returns the zero value for the map type's element.
// "missingkey=error"
// Execution stops immediately with an error.
//
func (s *HTMLEngine) Option(opt ...string) *HTMLEngine {
s.rmu.Lock()
s.options = append(s.options, opt...)
s.rmu.Unlock()
return s
}
// Delims sets the action delimiters to the specified strings, to be used in
// templates. An empty delimiter stands for the
// corresponding default: {{ or }}.
func (s *HTMLEngine) Delims(left, right string) *HTMLEngine {
s.left, s.right = left, right
return s
}
// Layout sets the layout template file which inside should use
// the {{ yield }} func to yield the main template file
// and optionally {{partial/partial_r/render}} to render other template files like headers and footers
//
// The 'tmplLayoutFile' is a relative path of the templates base directory,
// for the template file with its extension.
//
// Example: HTML("./templates", ".html").Layout("layouts/mainLayout.html")
// // mainLayout.html is inside: "./templates/layouts/".
//
// Note: Layout can be changed for a specific call
// action with the option: "layout" on the iris' context.Render function.
func (s *HTMLEngine) Layout(layoutFile string) *HTMLEngine {
s.layout = layoutFile
return s
}
// AddLayoutFunc adds the function to the template's layout-only function map.
// It is legal to overwrite elements of the default layout actions:
// - yield func() (template.HTML, error)
// - current func() (string, error)
// - partial func(partialName string) (template.HTML, error)
// - partial_r func(partialName string) (template.HTML, error)
// - render func(fullPartialName string) (template.HTML, error).
func (s *HTMLEngine) AddLayoutFunc(funcName string, funcBody interface{}) *HTMLEngine {
s.rmu.Lock()
s.layoutFuncs[funcName] = funcBody
s.rmu.Unlock()
return s
}
// AddFunc adds the function to the template's function map.
// It is legal to overwrite elements of the default actions:
// - url func(routeName string, args ...string) string
// - urlpath func(routeName string, args ...string) string
// - render func(fullPartialName string) (template.HTML, error).
func (s *HTMLEngine) AddFunc(funcName string, funcBody interface{}) {
s.rmu.Lock()
s.funcs[funcName] = funcBody
s.rmu.Unlock()
}
// Load parses the templates to the engine.
// It's also responsible to add the necessary global functions.
//
// Returns an error if something bad happens, user is responsible to catch it.
func (s *HTMLEngine) Load() error {
// No need to make this with a complicated and "pro" way, just add lockers to the `ExecuteWriter`.
// if `Reload(true)` and add a note for non conc access on dev mode.
// atomic.StoreUint32(&s.isLoading, 1)
// s.rmu.Lock()
// defer func() {
// s.rmu.Unlock()
// atomic.StoreUint32(&s.isLoading, 0)
// }()
if s.assetFn != nil && s.namesFn != nil {
// NOT NECESSARY "fix" of https://github.com/kataras/iris/issues/784,
// IT'S BAD CODE WRITTEN WE KEEP HERE ONLY FOR A REMINDER
// for any future questions.
//
// if strings.HasPrefix(s.directory, "../") {
// // this and some more additions are fixes for https://github.com/kataras/iris/issues/784
// // however, the dev SHOULD
// // run the go-bindata command from the "$dir" parent directory
// // and just use the ./$dir in the declaration,
// // so all these fixes are not really necessary but they are here
// // for the future
// dir, err := filepath.Abs(s.directory)
// // the absolute dir here can be invalid if running from other
// // folder but we really don't care
// // when we're working with the bindata because
// // we only care for its relative directory
// // see `loadAssets` for more.
// if err != nil {
// return err
// }
// s.directory = dir
// }
// embedded
return s.loadAssets()
}
// load from directory, make the dir absolute here too.
dir, err := filepath.Abs(s.directory)
if err != nil {
return err
}
if _, err := os.Stat(dir); os.IsNotExist(err) {
return err
}
// change the directory field configuration, load happens after directory has been set, so we will not have any problems here.
s.directory = dir
return s.loadDirectory()
}
// loadDirectory builds the templates from directory.
func (s *HTMLEngine) loadDirectory() error {
dir, extension := s.directory, s.extension
var templateErr error
s.Templates = template.New(dir)
s.Templates.Delims(s.left, s.right)
filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
if info == nil || info.IsDir() {
} else {
rel, err := filepath.Rel(dir, path)
if err != nil {
templateErr = err
return err
}
ext := filepath.Ext(path)
if ext == extension {
buf, err := ioutil.ReadFile(path)
if err != nil {
templateErr = err
return err
}
contents := string(buf)
name := filepath.ToSlash(rel)
tmpl := s.Templates.New(name)
tmpl.Option(s.options...)
if s.middleware != nil {
contents, err = s.middleware(name, buf)
}
if err != nil {
templateErr = err
return err
}
// s.mu.Lock()
// Add our funcmaps.
_, err = tmpl.Funcs(emptyFuncs).Funcs(s.funcs).Parse(contents)
// s.mu.Unlock()
if err != nil {
templateErr = err
return err
}
}
}
return nil
})
return templateErr
}
// loadAssets loads the templates by binary (go-bindata for embedded).
func (s *HTMLEngine) loadAssets() error {
virtualDirectory, virtualExtension := s.directory, s.extension
assetFn, namesFn := s.assetFn, s.namesFn
var templateErr error
s.Templates = template.New(virtualDirectory)
s.Templates.Delims(s.left, s.right)
names := namesFn()
if len(virtualDirectory) > 0 {
if virtualDirectory[0] == '.' { // first check for .wrong
virtualDirectory = virtualDirectory[1:]
}
if virtualDirectory[0] == '/' || virtualDirectory[0] == os.PathSeparator { // second check for /something, (or ./something if we had dot on 0 it will be removed
virtualDirectory = virtualDirectory[1:]
}
}
for _, path := range names {
// if filepath.IsAbs(virtualDirectory) {
// // fixes https://github.com/kataras/iris/issues/784
// // we take the absolute fullpath of the template file.
// pathFileAbs, err := filepath.Abs(path)
// if err != nil {
// templateErr = err
// continue
// }
//
// path = pathFileAbs
// }
// bindata may contain more files than the templates
// so keep that check as it's.
if !strings.HasPrefix(path, virtualDirectory) {
continue
}
ext := filepath.Ext(path)
// check if extension matches
if ext == virtualExtension {
// take the relative path of the path as base of
// virtualDirectory (the absolute path of the view engine that dev passed).
rel, err := filepath.Rel(virtualDirectory, path)
if err != nil {
templateErr = err
continue
}
// // take the current working directory
// cpath, err := filepath.Abs(".")
// if err == nil {
// // set the path as relative to "path" of the current working dir.
// // fixes https://github.com/kataras/iris/issues/784
// rpath, err := filepath.Rel(cpath, path)
// // fix view: Asset not found for path ''
// if err == nil && rpath != "" {
// path = rpath
// }
// }
buf, err := assetFn(path)
if err != nil {
templateErr = fmt.Errorf("%v for path '%s'", err, path)
continue
}
contents := string(buf)
name := filepath.ToSlash(rel)
// name should be the filename of the template.
tmpl := s.Templates.New(name)
tmpl.Option(s.options...)
if s.middleware != nil {
contents, err = s.middleware(name, buf)
if err != nil {
templateErr = fmt.Errorf("%v for name '%s'", err, name)
continue
}
}
// Add our funcmaps.
tmpl.Funcs(emptyFuncs).Funcs(s.funcs).Parse(contents)
}
}
return templateErr
}
func (s *HTMLEngine) executeTemplateBuf(name string, binding interface{}) (*bytes.Buffer, error) {
buf := new(bytes.Buffer)
err := s.Templates.ExecuteTemplate(buf, name, binding)
return buf, err
}
func (s *HTMLEngine) layoutFuncsFor(name string, binding interface{}) {
funcs := template.FuncMap{
"yield": func() (template.HTML, error) {
buf, err := s.executeTemplateBuf(name, binding)
// Return safe HTML here since we are rendering our own template.
return template.HTML(buf.String()), err
},
"part": func(partName string) (template.HTML, error) {
nameTemp := strings.Replace(name, ".html", "", -1)
fullPartName := fmt.Sprintf("%s-%s", nameTemp, partName)
buf, err := s.executeTemplateBuf(fullPartName, binding)
if err != nil {
return "", nil
}
return template.HTML(buf.String()), err
},
"current": func() (string, error) {
return name, nil
},
"partial": func(partialName string) (template.HTML, error) {
fullPartialName := fmt.Sprintf("%s-%s", partialName, name)
if s.Templates.Lookup(fullPartialName) != nil {
buf, err := s.executeTemplateBuf(fullPartialName, binding)
return template.HTML(buf.String()), err
}
return "", nil
},
// partial related to current page,
// it would be easier for adding pages' style/script inline
// for example when using partial_r '.script' in layout.html
// templates/users/index.html would load templates/users/index.script.html
"partial_r": func(partialName string) (template.HTML, error) {
ext := filepath.Ext(name)
root := name[:len(name)-len(ext)]
fullPartialName := fmt.Sprintf("%s%s%s", root, partialName, ext)
if s.Templates.Lookup(fullPartialName) != nil {
buf, err := s.executeTemplateBuf(fullPartialName, binding)
return template.HTML(buf.String()), err
}
return "", nil
},
"render": func(fullPartialName string) (template.HTML, error) {
buf, err := s.executeTemplateBuf(fullPartialName, binding)
return template.HTML(buf.String()), err
},
}
for k, v := range s.layoutFuncs {
funcs[k] = v
}
if tpl := s.Templates.Lookup(name); tpl != nil {
tpl.Funcs(funcs)
}
}
func (s *HTMLEngine) runtimeFuncsFor(name string, binding interface{}) {
funcs := template.FuncMap{
"render": func(fullPartialName string) (template.HTML, error) {
buf, err := s.executeTemplateBuf(fullPartialName, binding)
return template.HTML(buf.String()), err
},
}
if tpl := s.Templates.Lookup(name); tpl != nil {
tpl.Funcs(funcs)
}
}
var zero = time.Time{}
// ExecuteWriter executes a template and writes its result to the w writer.
func (s *HTMLEngine) ExecuteWriter(w io.Writer, name string, layout string, bindingData interface{}) error {
// re-parse the templates if reload is enabled.
if s.reload {
// locks to fix #872, it's the simplest solution and the most correct,
// to execute writers with "wait list", one at a time.
s.rmu.Lock()
defer s.rmu.Unlock()
if err := s.Load(); err != nil {
return err
}
}
layout = getLayout(layout, s.layout)
if layout != "" {
s.layoutFuncsFor(name, bindingData)
name = layout
} else {
s.runtimeFuncsFor(name, bindingData)
}
return s.Templates.ExecuteTemplate(w, name, bindingData)
}
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