281 lines
9.0 KiB
Go
281 lines
9.0 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package template
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import (
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"fmt"
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"io"
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"io/ioutil"
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"path/filepath"
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"sync"
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"text/template"
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"text/template/parse"
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)
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// Template is a specialized template.Template that produces a safe HTML
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// document fragment.
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type Template struct {
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escaped bool
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// We could embed the text/template field, but it's safer not to because
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// we need to keep our version of the name space and the underlying
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// template's in sync.
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text *template.Template
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*nameSpace // common to all associated templates
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}
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// nameSpace is the data structure shared by all templates in an association.
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type nameSpace struct {
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mu sync.Mutex
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set map[string]*Template
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}
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// Execute applies a parsed template to the specified data object,
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// writing the output to wr.
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func (t *Template) Execute(wr io.Writer, data interface{}) (err error) {
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t.nameSpace.mu.Lock()
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if !t.escaped {
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if err = escapeTemplates(t, t.Name()); err != nil {
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t.escaped = true
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}
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}
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t.nameSpace.mu.Unlock()
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if err != nil {
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return
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}
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return t.text.Execute(wr, data)
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}
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// ExecuteTemplate applies the template associated with t that has the given
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// name to the specified data object and writes the output to wr.
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func (t *Template) ExecuteTemplate(wr io.Writer, name string, data interface{}) error {
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tmpl, err := t.lookupAndEscapeTemplate(wr, name)
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if err != nil {
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return err
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}
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return tmpl.text.Execute(wr, data)
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}
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// lookupAndEscapeTemplate guarantees that the template with the given name
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// is escaped, or returns an error if it cannot be. It returns the named
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// template.
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func (t *Template) lookupAndEscapeTemplate(wr io.Writer, name string) (tmpl *Template, err error) {
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t.nameSpace.mu.Lock()
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defer t.nameSpace.mu.Unlock()
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tmpl = t.set[name]
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if (tmpl == nil) != (t.text.Lookup(name) == nil) {
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panic("html/template internal error: template escaping out of sync")
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}
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if tmpl != nil && !tmpl.escaped {
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err = escapeTemplates(tmpl, name)
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}
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return tmpl, err
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}
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// Parse parses a string into a template. Nested template definitions
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// will be associated with the top-level template t. Parse may be
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// called multiple times to parse definitions of templates to associate
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// with t. It is an error if a resulting template is non-empty (contains
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// content other than template definitions) and would replace a
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// non-empty template with the same name. (In multiple calls to Parse
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// with the same receiver template, only one call can contain text
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// other than space, comments, and template definitions.)
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func (t *Template) Parse(src string) (*Template, error) {
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t.nameSpace.mu.Lock()
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t.escaped = false
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t.nameSpace.mu.Unlock()
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ret, err := t.text.Parse(src)
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if err != nil {
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return nil, err
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}
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// In general, all the named templates might have changed underfoot.
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// Regardless, some new ones may have been defined.
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// The template.Template set has been updated; update ours.
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t.nameSpace.mu.Lock()
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defer t.nameSpace.mu.Unlock()
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for _, v := range ret.Templates() {
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name := v.Name()
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tmpl := t.set[name]
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if tmpl == nil {
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tmpl = t.new(name)
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}
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tmpl.escaped = false
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tmpl.text = v
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}
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return t, nil
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}
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// AddParseTree is unimplemented.
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func (t *Template) AddParseTree(name string, tree *parse.Tree) error {
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return fmt.Errorf("html/template: AddParseTree unimplemented")
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}
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// Clone is unimplemented.
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func (t *Template) Clone(name string) error {
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return fmt.Errorf("html/template: Clone unimplemented")
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}
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// New allocates a new HTML template with the given name.
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func New(name string) *Template {
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tmpl := &Template{
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false,
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template.New(name),
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&nameSpace{
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set: make(map[string]*Template),
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},
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}
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tmpl.set[name] = tmpl
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return tmpl
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}
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// New allocates a new HTML template associated with the given one
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// and with the same delimiters. The association, which is transitive,
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// allows one template to invoke another with a {{template}} action.
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func (t *Template) New(name string) *Template {
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t.nameSpace.mu.Lock()
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defer t.nameSpace.mu.Unlock()
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return t.new(name)
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}
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// new is the implementation of New, without the lock.
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func (t *Template) new(name string) *Template {
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tmpl := &Template{
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false,
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t.text.New(name),
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t.nameSpace,
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}
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tmpl.set[name] = tmpl
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return tmpl
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}
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// Name returns the name of the template.
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func (t *Template) Name() string {
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return t.text.Name()
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}
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// FuncMap is the type of the map defining the mapping from names to
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// functions. Each function must have either a single return value, or two
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// return values of which the second has type error. In that case, if the
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// second (error) argument evaluates to non-nil during execution, execution
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// terminates and Execute returns that error. FuncMap has the same base type
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// as template.FuncMap, copied here so clients need not import "text/template".
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type FuncMap map[string]interface{}
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// Funcs adds the elements of the argument map to the template's function map.
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// It panics if a value in the map is not a function with appropriate return
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// type. However, it is legal to overwrite elements of the map. The return
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// value is the template, so calls can be chained.
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func (t *Template) Funcs(funcMap FuncMap) *Template {
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t.text.Funcs(template.FuncMap(funcMap))
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return t
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}
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// Delims sets the action delimiters to the specified strings, to be used in
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// subsequent calls to Parse, ParseFiles, or ParseGlob. Nested template
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// definitions will inherit the settings. An empty delimiter stands for the
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// corresponding default: {{ or }}.
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// The return value is the template, so calls can be chained.
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func (t *Template) Delims(left, right string) *Template {
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t.text.Delims(left, right)
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return t
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}
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// Lookup returns the template with the given name that is associated with t,
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// or nil if there is no such template.
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func (t *Template) Lookup(name string) *Template {
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t.nameSpace.mu.Lock()
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defer t.nameSpace.mu.Unlock()
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return t.set[name]
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}
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// Must panics if err is non-nil in the same way as template.Must.
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func Must(t *Template, err error) *Template {
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if err != nil {
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panic(err)
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}
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return t
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}
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// ParseFiles creates a new Template and parses the template definitions from
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// the named files. The returned template's name will have the (base) name and
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// (parsed) contents of the first file. There must be at least one file.
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// If an error occurs, parsing stops and the returned *Template is nil.
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func ParseFiles(filenames ...string) (*Template, error) {
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return parseFiles(nil, filenames...)
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}
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// ParseFiles parses the named files and associates the resulting templates with
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// t. If an error occurs, parsing stops and the returned template is nil;
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// otherwise it is t. There must be at least one file.
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func (t *Template) ParseFiles(filenames ...string) (*Template, error) {
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return parseFiles(t, filenames...)
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}
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// parseFiles is the helper for the method and function. If the argument
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// template is nil, it is created from the first file.
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func parseFiles(t *Template, filenames ...string) (*Template, error) {
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if len(filenames) == 0 {
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// Not really a problem, but be consistent.
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return nil, fmt.Errorf("template: no files named in call to ParseFiles")
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}
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for _, filename := range filenames {
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b, err := ioutil.ReadFile(filename)
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if err != nil {
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return nil, err
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}
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s := string(b)
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name := filepath.Base(filename)
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// First template becomes return value if not already defined,
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// and we use that one for subsequent New calls to associate
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// all the templates together. Also, if this file has the same name
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// as t, this file becomes the contents of t, so
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// t, err := New(name).Funcs(xxx).ParseFiles(name)
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// works. Otherwise we create a new template associated with t.
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var tmpl *Template
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if t == nil {
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t = New(name)
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}
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if name == t.Name() {
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tmpl = t
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} else {
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tmpl = t.New(name)
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}
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_, err = tmpl.Parse(s)
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if err != nil {
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return nil, err
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}
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}
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return t, nil
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}
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// ParseGlob creates a new Template and parses the template definitions from the
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// files identified by the pattern, which must match at least one file. The
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// returned template will have the (base) name and (parsed) contents of the
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// first file matched by the pattern. ParseGlob is equivalent to calling
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// ParseFiles with the list of files matched by the pattern.
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func ParseGlob(pattern string) (*Template, error) {
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return parseGlob(nil, pattern)
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}
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// ParseGlob parses the template definitions in the files identified by the
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// pattern and associates the resulting templates with t. The pattern is
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// processed by filepath.Glob and must match at least one file. ParseGlob is
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// equivalent to calling t.ParseFiles with the list of files matched by the
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// pattern.
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func (t *Template) ParseGlob(pattern string) (*Template, error) {
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return parseGlob(t, pattern)
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}
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// parseGlob is the implementation of the function and method ParseGlob.
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func parseGlob(t *Template, pattern string) (*Template, error) {
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filenames, err := filepath.Glob(pattern)
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if err != nil {
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return nil, err
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}
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if len(filenames) == 0 {
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return nil, fmt.Errorf("template: pattern matches no files: %#q", pattern)
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}
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return parseFiles(t, filenames...)
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}
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