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Source file src/html/template/context.go

Documentation: html/template

  // 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 (
  // context describes the state an HTML parser must be in when it reaches the
  // portion of HTML produced by evaluating a particular template node.
  // The zero value of type context is the start context for a template that
  // produces an HTML fragment as defined at
  // http://www.w3.org/TR/html5/syntax.html#the-end
  // where the context element is null.
  type context struct {
  	state   state
  	delim   delim
  	urlPart urlPart
  	jsCtx   jsCtx
  	attr    attr
  	element element
  	err     *Error
  func (c context) String() string {
  	return fmt.Sprintf("{%v %v %v %v %v %v %v}", c.state, c.delim, c.urlPart, c.jsCtx, c.attr, c.element, c.err)
  // eq reports whether two contexts are equal.
  func (c context) eq(d context) bool {
  	return c.state == d.state &&
  		c.delim == d.delim &&
  		c.urlPart == d.urlPart &&
  		c.jsCtx == d.jsCtx &&
  		c.attr == d.attr &&
  		c.element == d.element &&
  		c.err == d.err
  // mangle produces an identifier that includes a suffix that distinguishes it
  // from template names mangled with different contexts.
  func (c context) mangle(templateName string) string {
  	// The mangled name for the default context is the input templateName.
  	if c.state == stateText {
  		return templateName
  	s := templateName + "$htmltemplate_" + c.state.String()
  	if c.delim != 0 {
  		s += "_" + c.delim.String()
  	if c.urlPart != 0 {
  		s += "_" + c.urlPart.String()
  	if c.jsCtx != 0 {
  		s += "_" + c.jsCtx.String()
  	if c.attr != 0 {
  		s += "_" + c.attr.String()
  	if c.element != 0 {
  		s += "_" + c.element.String()
  	return s
  // state describes a high-level HTML parser state.
  // It bounds the top of the element stack, and by extension the HTML insertion
  // mode, but also contains state that does not correspond to anything in the
  // HTML5 parsing algorithm because a single token production in the HTML
  // grammar may contain embedded actions in a template. For instance, the quoted
  // HTML attribute produced by
  //     <div title="Hello {{.World}}">
  // is a single token in HTML's grammar but in a template spans several nodes.
  type state uint8
  const (
  	// stateText is parsed character data. An HTML parser is in
  	// this state when its parse position is outside an HTML tag,
  	// directive, comment, and special element body.
  	stateText state = iota
  	// stateTag occurs before an HTML attribute or the end of a tag.
  	// stateAttrName occurs inside an attribute name.
  	// It occurs between the ^'s in ` ^name^ = value`.
  	// stateAfterName occurs after an attr name has ended but before any
  	// equals sign. It occurs between the ^'s in ` name^ ^= value`.
  	// stateBeforeValue occurs after the equals sign but before the value.
  	// It occurs between the ^'s in ` name =^ ^value`.
  	// stateHTMLCmt occurs inside an <!-- HTML comment -->.
  	// stateRCDATA occurs inside an RCDATA element (<textarea> or <title>)
  	// as described at http://www.w3.org/TR/html5/syntax.html#elements-0
  	// stateAttr occurs inside an HTML attribute whose content is text.
  	// stateURL occurs inside an HTML attribute whose content is a URL.
  	// stateSrcset occurs inside an HTML srcset attribute.
  	// stateJS occurs inside an event handler or script element.
  	// stateJSDqStr occurs inside a JavaScript double quoted string.
  	// stateJSSqStr occurs inside a JavaScript single quoted string.
  	// stateJSRegexp occurs inside a JavaScript regexp literal.
  	// stateJSBlockCmt occurs inside a JavaScript /* block comment */.
  	// stateJSLineCmt occurs inside a JavaScript // line comment.
  	// stateCSS occurs inside a <style> element or style attribute.
  	// stateCSSDqStr occurs inside a CSS double quoted string.
  	// stateCSSSqStr occurs inside a CSS single quoted string.
  	// stateCSSDqURL occurs inside a CSS double quoted url("...").
  	// stateCSSSqURL occurs inside a CSS single quoted url('...').
  	// stateCSSURL occurs inside a CSS unquoted url(...).
  	// stateCSSBlockCmt occurs inside a CSS /* block comment */.
  	// stateCSSLineCmt occurs inside a CSS // line comment.
  	// stateError is an infectious error state outside any valid
  	// HTML/CSS/JS construct.
  var stateNames = [...]string{
  	stateText:        "stateText",
  	stateTag:         "stateTag",
  	stateAttrName:    "stateAttrName",
  	stateAfterName:   "stateAfterName",
  	stateBeforeValue: "stateBeforeValue",
  	stateHTMLCmt:     "stateHTMLCmt",
  	stateRCDATA:      "stateRCDATA",
  	stateAttr:        "stateAttr",
  	stateURL:         "stateURL",
  	stateSrcset:      "stateSrcset",
  	stateJS:          "stateJS",
  	stateJSDqStr:     "stateJSDqStr",
  	stateJSSqStr:     "stateJSSqStr",
  	stateJSRegexp:    "stateJSRegexp",
  	stateJSBlockCmt:  "stateJSBlockCmt",
  	stateJSLineCmt:   "stateJSLineCmt",
  	stateCSS:         "stateCSS",
  	stateCSSDqStr:    "stateCSSDqStr",
  	stateCSSSqStr:    "stateCSSSqStr",
  	stateCSSDqURL:    "stateCSSDqURL",
  	stateCSSSqURL:    "stateCSSSqURL",
  	stateCSSURL:      "stateCSSURL",
  	stateCSSBlockCmt: "stateCSSBlockCmt",
  	stateCSSLineCmt:  "stateCSSLineCmt",
  	stateError:       "stateError",
  func (s state) String() string {
  	if int(s) < len(stateNames) {
  		return stateNames[s]
  	return fmt.Sprintf("illegal state %d", int(s))
  // isComment is true for any state that contains content meant for template
  // authors & maintainers, not for end-users or machines.
  func isComment(s state) bool {
  	switch s {
  	case stateHTMLCmt, stateJSBlockCmt, stateJSLineCmt, stateCSSBlockCmt, stateCSSLineCmt:
  		return true
  	return false
  // isInTag return whether s occurs solely inside an HTML tag.
  func isInTag(s state) bool {
  	switch s {
  	case stateTag, stateAttrName, stateAfterName, stateBeforeValue, stateAttr:
  		return true
  	return false
  // delim is the delimiter that will end the current HTML attribute.
  type delim uint8
  const (
  	// delimNone occurs outside any attribute.
  	delimNone delim = iota
  	// delimDoubleQuote occurs when a double quote (") closes the attribute.
  	// delimSingleQuote occurs when a single quote (') closes the attribute.
  	// delimSpaceOrTagEnd occurs when a space or right angle bracket (>)
  	// closes the attribute.
  var delimNames = [...]string{
  	delimNone:          "delimNone",
  	delimDoubleQuote:   "delimDoubleQuote",
  	delimSingleQuote:   "delimSingleQuote",
  	delimSpaceOrTagEnd: "delimSpaceOrTagEnd",
  func (d delim) String() string {
  	if int(d) < len(delimNames) {
  		return delimNames[d]
  	return fmt.Sprintf("illegal delim %d", int(d))
  // urlPart identifies a part in an RFC 3986 hierarchical URL to allow different
  // encoding strategies.
  type urlPart uint8
  const (
  	// urlPartNone occurs when not in a URL, or possibly at the start:
  	// ^ in "^http://auth/path?k=v#frag".
  	urlPartNone urlPart = iota
  	// urlPartPreQuery occurs in the scheme, authority, or path; between the
  	// ^s in "h^ttp://auth/path^?k=v#frag".
  	// urlPartQueryOrFrag occurs in the query portion between the ^s in
  	// "http://auth/path?^k=v#frag^".
  	// urlPartUnknown occurs due to joining of contexts both before and
  	// after the query separator.
  var urlPartNames = [...]string{
  	urlPartNone:        "urlPartNone",
  	urlPartPreQuery:    "urlPartPreQuery",
  	urlPartQueryOrFrag: "urlPartQueryOrFrag",
  	urlPartUnknown:     "urlPartUnknown",
  func (u urlPart) String() string {
  	if int(u) < len(urlPartNames) {
  		return urlPartNames[u]
  	return fmt.Sprintf("illegal urlPart %d", int(u))
  // jsCtx determines whether a '/' starts a regular expression literal or a
  // division operator.
  type jsCtx uint8
  const (
  	// jsCtxRegexp occurs where a '/' would start a regexp literal.
  	jsCtxRegexp jsCtx = iota
  	// jsCtxDivOp occurs where a '/' would start a division operator.
  	// jsCtxUnknown occurs where a '/' is ambiguous due to context joining.
  func (c jsCtx) String() string {
  	switch c {
  	case jsCtxRegexp:
  		return "jsCtxRegexp"
  	case jsCtxDivOp:
  		return "jsCtxDivOp"
  	case jsCtxUnknown:
  		return "jsCtxUnknown"
  	return fmt.Sprintf("illegal jsCtx %d", int(c))
  // element identifies the HTML element when inside a start tag or special body.
  // Certain HTML element (for example <script> and <style>) have bodies that are
  // treated differently from stateText so the element type is necessary to
  // transition into the correct context at the end of a tag and to identify the
  // end delimiter for the body.
  type element uint8
  const (
  	// elementNone occurs outside a special tag or special element body.
  	elementNone element = iota
  	// elementScript corresponds to the raw text <script> element
  	// with JS MIME type or no type attribute.
  	// elementStyle corresponds to the raw text <style> element.
  	// elementTextarea corresponds to the RCDATA <textarea> element.
  	// elementTitle corresponds to the RCDATA <title> element.
  var elementNames = [...]string{
  	elementNone:     "elementNone",
  	elementScript:   "elementScript",
  	elementStyle:    "elementStyle",
  	elementTextarea: "elementTextarea",
  	elementTitle:    "elementTitle",
  func (e element) String() string {
  	if int(e) < len(elementNames) {
  		return elementNames[e]
  	return fmt.Sprintf("illegal element %d", int(e))
  // attr identifies the current HTML attribute when inside the attribute,
  // that is, starting from stateAttrName until stateTag/stateText (exclusive).
  type attr uint8
  const (
  	// attrNone corresponds to a normal attribute or no attribute.
  	attrNone attr = iota
  	// attrScript corresponds to an event handler attribute.
  	// attrScriptType corresponds to the type attribute in script HTML element
  	// attrStyle corresponds to the style attribute whose value is CSS.
  	// attrURL corresponds to an attribute whose value is a URL.
  	// attrSrcset corresponds to a srcset attribute.
  var attrNames = [...]string{
  	attrNone:       "attrNone",
  	attrScript:     "attrScript",
  	attrScriptType: "attrScriptType",
  	attrStyle:      "attrStyle",
  	attrURL:        "attrURL",
  	attrSrcset:     "attrSrcset",
  func (a attr) String() string {
  	if int(a) < len(attrNames) {
  		return attrNames[a]
  	return fmt.Sprintf("illegal attr %d", int(a))

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