// Copyright 2011 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.

package template

import (
	
	
	
	
	
	
	
	
	
)

// Template is a specialized Template from "text/template" that produces a safe
// HTML document fragment.
type Template struct {
	// Sticky error if escaping fails, or escapeOK if succeeded.
	escapeErr error
	// We could embed the text/template field, but it's safer not to because
	// we need to keep our version of the name space and the underlying
	// template's in sync.
	text *template.Template
	// The underlying template's parse tree, updated to be HTML-safe.
	Tree       *parse.Tree
	*nameSpace // common to all associated templates
}

// escapeOK is a sentinel value used to indicate valid escaping.
var escapeOK = fmt.Errorf("template escaped correctly")

// nameSpace is the data structure shared by all templates in an association.
type nameSpace struct {
	mu      sync.Mutex
	set     map[string]*Template
	escaped bool
	esc     escaper
}

// Templates returns a slice of the templates associated with t, including t
// itself.
func ( *Template) () []*Template {
	 := .nameSpace
	.mu.Lock()
	defer .mu.Unlock()
	// Return a slice so we don't expose the map.
	 := make([]*Template, 0, len(.set))
	for ,  := range .set {
		 = append(, )
	}
	return 
}

// 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 ( *Template) ( ...string) *Template {
	.text.Option(...)
	return 
}

// checkCanParse checks whether it is OK to parse templates.
// If not, it returns an error.
func ( *Template) () error {
	if  == nil {
		return nil
	}
	.nameSpace.mu.Lock()
	defer .nameSpace.mu.Unlock()
	if .nameSpace.escaped {
		return fmt.Errorf("html/template: cannot Parse after Execute")
	}
	return nil
}

// escape escapes all associated templates.
func ( *Template) () error {
	.nameSpace.mu.Lock()
	defer .nameSpace.mu.Unlock()
	.nameSpace.escaped = true
	if .escapeErr == nil {
		if .Tree == nil {
			return fmt.Errorf("template: %q is an incomplete or empty template", .Name())
		}
		if  := escapeTemplate(, .text.Root, .Name());  != nil {
			return 
		}
	} else if .escapeErr != escapeOK {
		return .escapeErr
	}
	return nil
}

// Execute applies a parsed template to the specified data object,
// writing the output to wr.
// If an error occurs executing the template or writing its output,
// execution stops, but partial results may already have been written to
// the output writer.
// A template may be executed safely in parallel, although if parallel
// executions share a Writer the output may be interleaved.
func ( *Template) ( io.Writer,  interface{}) error {
	if  := .escape();  != nil {
		return 
	}
	return .text.Execute(, )
}

// ExecuteTemplate applies the template associated with t that has the given
// name to the specified data object and writes the output to wr.
// If an error occurs executing the template or writing its output,
// execution stops, but partial results may already have been written to
// the output writer.
// A template may be executed safely in parallel, although if parallel
// executions share a Writer the output may be interleaved.
func ( *Template) ( io.Writer,  string,  interface{}) error {
	,  := .lookupAndEscapeTemplate()
	if  != nil {
		return 
	}
	return .text.Execute(, )
}

// lookupAndEscapeTemplate guarantees that the template with the given name
// is escaped, or returns an error if it cannot be. It returns the named
// template.
func ( *Template) ( string) ( *Template,  error) {
	.nameSpace.mu.Lock()
	defer .nameSpace.mu.Unlock()
	.nameSpace.escaped = true
	 = .set[]
	if  == nil {
		return nil, fmt.Errorf("html/template: %q is undefined", )
	}
	if .escapeErr != nil && .escapeErr != escapeOK {
		return nil, .escapeErr
	}
	if .text.Tree == nil || .text.Root == nil {
		return nil, fmt.Errorf("html/template: %q is an incomplete template", )
	}
	if .text.Lookup() == nil {
		panic("html/template internal error: template escaping out of sync")
	}
	if .escapeErr == nil {
		 = escapeTemplate(, .text.Root, )
	}
	return , 
}

// DefinedTemplates returns a string listing the defined templates,
// prefixed by the string "; defined templates are: ". If there are none,
// it returns the empty string. Used to generate an error message.
func ( *Template) () string {
	return .text.DefinedTemplates()
}

// Parse parses text as a template body for t.
// Named template definitions ({{define ...}} or {{block ...}} statements) in text
// define additional templates associated with t and are removed from the
// definition of t itself.
//
// Templates can be redefined in successive calls to Parse,
// before the first use of Execute on t or any associated template.
// A template definition with a body containing only white space and comments
// is considered empty and will not replace an existing template's body.
// This allows using Parse to add new named template definitions without
// overwriting the main template body.
func ( *Template) ( string) (*Template, error) {
	if  := .checkCanParse();  != nil {
		return nil, 
	}

	,  := .text.Parse()
	if  != nil {
		return nil, 
	}

	// In general, all the named templates might have changed underfoot.
	// Regardless, some new ones may have been defined.
	// The template.Template set has been updated; update ours.
	.nameSpace.mu.Lock()
	defer .nameSpace.mu.Unlock()
	for ,  := range .Templates() {
		 := .Name()
		 := .set[]
		if  == nil {
			 = .new()
		}
		.text = 
		.Tree = .Tree
	}
	return , nil
}

// AddParseTree creates a new template with the name and parse tree
// and associates it with t.
//
// It returns an error if t or any associated template has already been executed.
func ( *Template) ( string,  *parse.Tree) (*Template, error) {
	if  := .checkCanParse();  != nil {
		return nil, 
	}

	.nameSpace.mu.Lock()
	defer .nameSpace.mu.Unlock()
	,  := .text.AddParseTree(, )
	if  != nil {
		return nil, 
	}
	 := &Template{
		nil,
		,
		.Tree,
		.nameSpace,
	}
	.set[] = 
	return , nil
}

// Clone returns a duplicate of the template, including all associated
// templates. The actual representation is not copied, but the name space of
// associated templates is, so further calls to Parse in the copy will add
// templates to the copy but not to the original. Clone can be used to prepare
// common templates and use them with variant definitions for other templates
// by adding the variants after the clone is made.
//
// It returns an error if t has already been executed.
func ( *Template) () (*Template, error) {
	.nameSpace.mu.Lock()
	defer .nameSpace.mu.Unlock()
	if .escapeErr != nil {
		return nil, fmt.Errorf("html/template: cannot Clone %q after it has executed", .Name())
	}
	,  := .text.Clone()
	if  != nil {
		return nil, 
	}
	 := &nameSpace{set: make(map[string]*Template)}
	.esc = makeEscaper()
	 := &Template{
		nil,
		,
		.Tree,
		,
	}
	.set[.Name()] = 
	for ,  := range .Templates() {
		 := .Name()
		 := .set[]
		if  == nil || .escapeErr != nil {
			return nil, fmt.Errorf("html/template: cannot Clone %q after it has executed", .Name())
		}
		.Tree = .Tree.Copy()
		.set[] = &Template{
			nil,
			,
			.Tree,
			.nameSpace,
		}
	}
	// Return the template associated with the name of this template.
	return .set[.Name()], nil
}

// New allocates a new HTML template with the given name.
func ( string) *Template {
	 := &nameSpace{set: make(map[string]*Template)}
	.esc = makeEscaper()
	 := &Template{
		nil,
		template.New(),
		nil,
		,
	}
	.set[] = 
	return 
}

// New allocates a new HTML template associated with the given one
// and with the same delimiters. The association, which is transitive,
// allows one template to invoke another with a {{template}} action.
//
// If a template with the given name already exists, the new HTML template
// will replace it. The existing template will be reset and disassociated with
// t.
func ( *Template) ( string) *Template {
	.nameSpace.mu.Lock()
	defer .nameSpace.mu.Unlock()
	return .new()
}

// new is the implementation of New, without the lock.
func ( *Template) ( string) *Template {
	 := &Template{
		nil,
		.text.New(),
		nil,
		.nameSpace,
	}
	if ,  := .set[];  {
		 := New(.Name())
		* = *
	}
	.set[] = 
	return 
}

// Name returns the name of the template.
func ( *Template) () string {
	return .text.Name()
}

// FuncMap is the type of the map defining the mapping from names to
// functions. Each function must have either a single return value, or two
// return values of which the second has type error. In that case, if the
// second (error) argument evaluates to non-nil during execution, execution
// terminates and Execute returns that error. FuncMap has the same base type
// as FuncMap in "text/template", copied here so clients need not import
// "text/template".
type FuncMap map[string]interface{}

// Funcs adds the elements of the argument map to the template's function map.
// It must be called before the template is parsed.
// It panics if a value in the map is not a function with appropriate return
// type. However, it is legal to overwrite elements of the map. The return
// value is the template, so calls can be chained.
func ( *Template) ( FuncMap) *Template {
	.text.Funcs(template.FuncMap())
	return 
}

// Delims sets the action delimiters to the specified strings, to be used in
// subsequent calls to Parse, ParseFiles, or ParseGlob. Nested template
// definitions will inherit the settings. An empty delimiter stands for the
// corresponding default: {{ or }}.
// The return value is the template, so calls can be chained.
func ( *Template) (,  string) *Template {
	.text.Delims(, )
	return 
}

// Lookup returns the template with the given name that is associated with t,
// or nil if there is no such template.
func ( *Template) ( string) *Template {
	.nameSpace.mu.Lock()
	defer .nameSpace.mu.Unlock()
	return .set[]
}

// Must is a helper that wraps a call to a function returning (*Template, error)
// and panics if the error is non-nil. It is intended for use in variable initializations
// such as
//	var t = template.Must(template.New("name").Parse("html"))
func ( *Template,  error) *Template {
	if  != nil {
		panic()
	}
	return 
}

// ParseFiles creates a new Template and parses the template definitions from
// the named files. The returned template's name will have the (base) name and
// (parsed) contents of the first file. There must be at least one file.
// If an error occurs, parsing stops and the returned *Template is nil.
//
// When parsing multiple files with the same name in different directories,
// the last one mentioned will be the one that results.
// For instance, ParseFiles("a/foo", "b/foo") stores "b/foo" as the template
// named "foo", while "a/foo" is unavailable.
func ( ...string) (*Template, error) {
	return parseFiles(nil, readFileOS, ...)
}

// ParseFiles parses the named files and associates the resulting templates with
// t. If an error occurs, parsing stops and the returned template is nil;
// otherwise it is t. There must be at least one file.
//
// When parsing multiple files with the same name in different directories,
// the last one mentioned will be the one that results.
//
// ParseFiles returns an error if t or any associated template has already been executed.
func ( *Template) ( ...string) (*Template, error) {
	return parseFiles(, readFileOS, ...)
}

// parseFiles is the helper for the method and function. If the argument
// template is nil, it is created from the first file.
func parseFiles( *Template,  func(string) (string, []byte, error),  ...string) (*Template, error) {
	if  := .checkCanParse();  != nil {
		return nil, 
	}

	if len() == 0 {
		// Not really a problem, but be consistent.
		return nil, fmt.Errorf("html/template: no files named in call to ParseFiles")
	}
	for ,  := range  {
		, ,  := ()
		if  != nil {
			return nil, 
		}
		 := string()
		// First template becomes return value if not already defined,
		// and we use that one for subsequent New calls to associate
		// all the templates together. Also, if this file has the same name
		// as t, this file becomes the contents of t, so
		//  t, err := New(name).Funcs(xxx).ParseFiles(name)
		// works. Otherwise we create a new template associated with t.
		var  *Template
		if  == nil {
			 = New()
		}
		if  == .Name() {
			 = 
		} else {
			 = .New()
		}
		_,  = .Parse()
		if  != nil {
			return nil, 
		}
	}
	return , nil
}

// ParseGlob creates a new Template and parses the template definitions from
// the files identified by the pattern. The files are matched according to the
// semantics of filepath.Match, and the pattern must match at least one file.
// The returned template will have the (base) name and (parsed) contents of the
// first file matched by the pattern. ParseGlob is equivalent to calling
// ParseFiles with the list of files matched by the pattern.
//
// When parsing multiple files with the same name in different directories,
// the last one mentioned will be the one that results.
func ( string) (*Template, error) {
	return parseGlob(nil, )
}

// ParseGlob parses the template definitions in the files identified by the
// pattern and associates the resulting templates with t. The files are matched
// according to the semantics of filepath.Match, and the pattern must match at
// least one file. ParseGlob is equivalent to calling t.ParseFiles with the
// list of files matched by the pattern.
//
// When parsing multiple files with the same name in different directories,
// the last one mentioned will be the one that results.
//
// ParseGlob returns an error if t or any associated template has already been executed.
func ( *Template) ( string) (*Template, error) {
	return parseGlob(, )
}

// parseGlob is the implementation of the function and method ParseGlob.
func parseGlob( *Template,  string) (*Template, error) {
	if  := .checkCanParse();  != nil {
		return nil, 
	}
	,  := filepath.Glob()
	if  != nil {
		return nil, 
	}
	if len() == 0 {
		return nil, fmt.Errorf("html/template: pattern matches no files: %#q", )
	}
	return parseFiles(, readFileOS, ...)
}

// IsTrue reports whether the value is 'true', in the sense of not the zero of its type,
// and whether the value has a meaningful truth value. This is the definition of
// truth used by if and other such actions.
func ( interface{}) (,  bool) {
	return template.IsTrue()
}

// ParseFS is like ParseFiles or ParseGlob but reads from the file system fs
// instead of the host operating system's file system.
// It accepts a list of glob patterns.
// (Note that most file names serve as glob patterns matching only themselves.)
func ( fs.FS,  ...string) (*Template, error) {
	return parseFS(nil, , )
}

// ParseFS is like ParseFiles or ParseGlob but reads from the file system fs
// instead of the host operating system's file system.
// It accepts a list of glob patterns.
// (Note that most file names serve as glob patterns matching only themselves.)
func ( *Template) ( fs.FS,  ...string) (*Template, error) {
	return parseFS(, , )
}

func parseFS( *Template,  fs.FS,  []string) (*Template, error) {
	var  []string
	for ,  := range  {
		,  := fs.Glob(, )
		if  != nil {
			return nil, 
		}
		if len() == 0 {
			return nil, fmt.Errorf("template: pattern matches no files: %#q", )
		}
		 = append(, ...)
	}
	return parseFiles(, readFileFS(), ...)
}

func readFileOS( string) ( string,  []byte,  error) {
	 = filepath.Base()
	,  = os.ReadFile()
	return
}

func readFileFS( fs.FS) func(string) (string, []byte, error) {
	return func( string) ( string,  []byte,  error) {
		 = path.Base()
		,  = fs.ReadFile(, )
		return
	}
}