// escapeTree escapes the named template starting in the given context as
// necessary and returns its output context.
func (e *escaper) escapeTree(c context, node parse.Node, name string, line int) (context, string) {
// Mangle the template name with the input context to produce a reliable
// identifier.
dname := c.mangle(name)
e.called[dname] = true
if out, ok := e.output[dname]; ok {
// Already escaped.
return out, dname
}
t := e.template(name)
if t == nil {
// Two cases: The template exists but is empty, or has never been mentioned at
// all. Distinguish the cases in the error messages.
if e.tmpl.set[name] != nil {
return context{
state: stateError,
err: errorf(ErrNoSuchTemplate, node, line, "%q is an incomplete or empty template", name),
}, dname
}
return context{}, dname
}
if dname != name {
// Use any template derived during an earlier call to escapeTemplate
// with different top level templates, or clone if necessary.
dt := e.template(dname)
if dt == nil {
dt = template.New(dname)
dt.Tree = &parse.Tree{Name: dname, Root: t.Root.CopyList()}
e.derived[dname] = dt
}
t = dt
}
return e.computeOutCtx(c, t), dname
}
func ExampleTemplate() {
// Define a template.
const letter = `
Dear {{.Name}},
{{if .Attended}}
It was a pleasure to see you at the wedding.{{else}}
It is a shame you couldn't make it to the wedding.{{end}}
{{with .Gift}}Thank you for the lovely {{.}}.
{{end}}
Best wishes,
Josie
`
// Prepare some data to insert into the template.
type Recipient struct {
Name, Gift string
Attended bool
}
var recipients = []Recipient{
{"Aunt Mildred", "bone china tea set", true},
{"Uncle John", "moleskin pants", false},
{"Cousin Rodney", "", false},
}
// Create a new template and parse the letter into it.
t := template.Must(template.New("letter").Parse(letter))
// Execute the template for each recipient.
for _, r := range recipients {
err := t.Execute(os.Stdout, r)
if err != nil {
log.Println("executing template:", err)
}
}
// Output:
// Dear Aunt Mildred,
//
// It was a pleasure to see you at the wedding.
// Thank you for the lovely bone china tea set.
//
// Best wishes,
// Josie
//
// Dear Uncle John,
//
// It is a shame you couldn't make it to the wedding.
// Thank you for the lovely moleskin pants.
//
// Best wishes,
// Josie
//
// Dear Cousin Rodney,
//
// It is a shame you couldn't make it to the wedding.
//
// Best wishes,
// Josie
}
// New allocates a new HTML template with the given name.
func New(name string) *Template {
tmpl := &Template{
nil,
template.New(name),
nil,
&nameSpace{
set: make(map[string]*Template),
},
}
tmpl.set[name] = tmpl
return tmpl
}
// This example demonstrates a custom function to process template text.
// It installs the strings.Title function and uses it to
// Make Title Text Look Good In Our Template's Output.
func ExampleTemplate_func() {
// First we create a FuncMap with which to register the function.
funcMap := template.FuncMap{
// The name "title" is what the function will be called in the template text.
"title": strings.Title,
}
// A simple template definition to test our function.
// We print the input text several ways:
// - the original
// - title-cased
// - title-cased and then printed with %q
// - printed with %q and then title-cased.
const templateText = `
Input: {{printf "%q" .}}
Output 0: {{title .}}
Output 1: {{title . | printf "%q"}}
Output 2: {{printf "%q" . | title}}
`
// Create a template, add the function map, and parse the text.
tmpl, err := template.New("titleTest").Funcs(funcMap).Parse(templateText)
if err != nil {
log.Fatalf("parsing: %s", err)
}
// Run the template to verify the output.
err = tmpl.Execute(os.Stdout, "the go programming language")
if err != nil {
log.Fatalf("execution: %s", err)
}
// Output:
// Input: "the go programming language"
// Output 0: The Go Programming Language
// Output 1: "The Go Programming Language"
// Output 2: "The Go Programming Language"
}
func TestEnsurePipelineContains(t *testing.T) {
tests := []struct {
input, output string
ids []string
}{
{
"{{.X}}",
".X",
[]string{},
},
{
"{{.X | html}}",
".X | html",
[]string{},
},
{
"{{.X}}",
".X | html",
[]string{"html"},
},
{
"{{.X | html}}",
".X | html | urlquery",
[]string{"urlquery"},
},
{
"{{.X | html | urlquery}}",
".X | html | urlquery",
[]string{"urlquery"},
},
{
"{{.X | html | urlquery}}",
".X | html | urlquery",
[]string{"html", "urlquery"},
},
{
"{{.X | html | urlquery}}",
".X | html | urlquery",
[]string{"html"},
},
{
"{{.X | urlquery}}",
".X | html | urlquery",
[]string{"html", "urlquery"},
},
{
"{{.X | html | print}}",
".X | urlquery | html | print",
[]string{"urlquery", "html"},
},
{
"{{($).X | html | print}}",
"($).X | urlquery | html | print",
[]string{"urlquery", "html"},
},
{
"{{.X | print 2 | .f 3}}",
".X | print 2 | .f 3 | urlquery | html",
[]string{"urlquery", "html"},
},
{
"{{.X | html | print 2 | .f 3}}",
".X | urlquery | html | print 2 | .f 3",
[]string{"urlquery", "html"},
},
{
// covering issue 10801
"{{.X | js.x }}",
".X | js.x | urlquery | html",
[]string{"urlquery", "html"},
},
{
// covering issue 10801
"{{.X | (print 12 | js).x }}",
".X | (print 12 | js).x | urlquery | html",
[]string{"urlquery", "html"},
},
}
for i, test := range tests {
tmpl := template.Must(template.New("test").Parse(test.input))
action, ok := (tmpl.Tree.Root.Nodes[0].(*parse.ActionNode))
if !ok {
t.Errorf("#%d: First node is not an action: %s", i, test.input)
continue
}
pipe := action.Pipe
ensurePipelineContains(pipe, test.ids)
got := pipe.String()
if got != test.output {
t.Errorf("#%d: %s, %v: want\n\t%s\ngot\n\t%s", i, test.input, test.ids, test.output, got)
}
}
}
