lex.go

Documentation: text/template/parse

     1  // Copyright 2011 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package parse
     6  
     7  import (
     8  	"fmt"
     9  	"strings"
    10  	"unicode"
    11  	"unicode/utf8"
    12  )
    13  
    14  // item represents a token or text string returned from the scanner.
    15  type item struct {
    16  	typ  itemType // The type of this item.
    17  	pos  Pos      // The starting position, in bytes, of this item in the input string.
    18  	val  string   // The value of this item.
    19  	line int      // The line number at the start of this item.
    20  }
    21  
    22  func (i item) String() string {
    23  	switch {
    24  	case i.typ == itemEOF:
    25  		return "EOF"
    26  	case i.typ == itemError:
    27  		return i.val
    28  	case i.typ > itemKeyword:
    29  		return fmt.Sprintf("<%s>", i.val)
    30  	case len(i.val) > 10:
    31  		return fmt.Sprintf("%.10q...", i.val)
    32  	}
    33  	return fmt.Sprintf("%q", i.val)
    34  }
    35  
    36  // itemType identifies the type of lex items.
    37  type itemType int
    38  
    39  const (
    40  	itemError        itemType = iota // error occurred; value is text of error
    41  	itemBool                         // boolean constant
    42  	itemChar                         // printable ASCII character; grab bag for comma etc.
    43  	itemCharConstant                 // character constant
    44  	itemComment                      // comment text
    45  	itemComplex                      // complex constant (1+2i); imaginary is just a number
    46  	itemAssign                       // equals ('=') introducing an assignment
    47  	itemDeclare                      // colon-equals (':=') introducing a declaration
    48  	itemEOF
    49  	itemField      // alphanumeric identifier starting with '.'
    50  	itemIdentifier // alphanumeric identifier not starting with '.'
    51  	itemLeftDelim  // left action delimiter
    52  	itemLeftParen  // '(' inside action
    53  	itemNumber     // simple number, including imaginary
    54  	itemPipe       // pipe symbol
    55  	itemRawString  // raw quoted string (includes quotes)
    56  	itemRightDelim // right action delimiter
    57  	itemRightParen // ')' inside action
    58  	itemSpace      // run of spaces separating arguments
    59  	itemString     // quoted string (includes quotes)
    60  	itemText       // plain text
    61  	itemVariable   // variable starting with '$', such as '$' or  '$1' or '$hello'
    62  	// Keywords appear after all the rest.
    63  	itemKeyword  // used only to delimit the keywords
    64  	itemBlock    // block keyword
    65  	itemBreak    // break keyword
    66  	itemContinue // continue keyword
    67  	itemDot      // the cursor, spelled '.'
    68  	itemDefine   // define keyword
    69  	itemElse     // else keyword
    70  	itemEnd      // end keyword
    71  	itemIf       // if keyword
    72  	itemNil      // the untyped nil constant, easiest to treat as a keyword
    73  	itemRange    // range keyword
    74  	itemTemplate // template keyword
    75  	itemWith     // with keyword
    76  )
    77  
    78  var key = map[string]itemType{
    79  	".":        itemDot,
    80  	"block":    itemBlock,
    81  	"break":    itemBreak,
    82  	"continue": itemContinue,
    83  	"define":   itemDefine,
    84  	"else":     itemElse,
    85  	"end":      itemEnd,
    86  	"if":       itemIf,
    87  	"range":    itemRange,
    88  	"nil":      itemNil,
    89  	"template": itemTemplate,
    90  	"with":     itemWith,
    91  }
    92  
    93  const eof = -1
    94  
    95  // Trimming spaces.
    96  // If the action begins "{{- " rather than "{{", then all space/tab/newlines
    97  // preceding the action are trimmed; conversely if it ends " -}}" the
    98  // leading spaces are trimmed. This is done entirely in the lexer; the
    99  // parser never sees it happen. We require an ASCII space (' ', \t, \r, \n)
   100  // to be present to avoid ambiguity with things like "{{-3}}". It reads
   101  // better with the space present anyway. For simplicity, only ASCII
   102  // does the job.
   103  const (
   104  	spaceChars    = " \t\r\n"  // These are the space characters defined by Go itself.
   105  	trimMarker    = '-'        // Attached to left/right delimiter, trims trailing spaces from preceding/following text.
   106  	trimMarkerLen = Pos(1 + 1) // marker plus space before or after
   107  )
   108  
   109  // stateFn represents the state of the scanner as a function that returns the next state.
   110  type stateFn func(*lexer) stateFn
   111  
   112  // lexer holds the state of the scanner.
   113  type lexer struct {
   114  	name        string    // the name of the input; used only for error reports
   115  	input       string    // the string being scanned
   116  	leftDelim   string    // start of action
   117  	rightDelim  string    // end of action
   118  	emitComment bool      // emit itemComment tokens.
   119  	pos         Pos       // current position in the input
   120  	start       Pos       // start position of this item
   121  	atEOF       bool      // we have hit the end of input and returned eof
   122  	items       chan item // channel of scanned items
   123  	parenDepth  int       // nesting depth of ( ) exprs
   124  	line        int       // 1+number of newlines seen
   125  	startLine   int       // start line of this item
   126  	breakOK     bool      // break keyword allowed
   127  	continueOK  bool      // continue keyword allowed
   128  }
   129  
   130  // next returns the next rune in the input.
   131  func (l *lexer) next() rune {
   132  	if int(l.pos) >= len(l.input) {
   133  		l.atEOF = true
   134  		return eof
   135  	}
   136  	r, w := utf8.DecodeRuneInString(l.input[l.pos:])
   137  	l.pos += Pos(w)
   138  	if r == '\n' {
   139  		l.line++
   140  	}
   141  	return r
   142  }
   143  
   144  // peek returns but does not consume the next rune in the input.
   145  func (l *lexer) peek() rune {
   146  	r := l.next()
   147  	l.backup()
   148  	return r
   149  }
   150  
   151  // backup steps back one rune.
   152  func (l *lexer) backup() {
   153  	if !l.atEOF && l.pos > 0 {
   154  		r, w := utf8.DecodeLastRuneInString(l.input[:l.pos])
   155  		l.pos -= Pos(w)
   156  		// Correct newline count.
   157  		if r == '\n' {
   158  			l.line--
   159  		}
   160  	}
   161  }
   162  
   163  // emit passes an item back to the client.
   164  func (l *lexer) emit(t itemType) {
   165  	l.items <- item{t, l.start, l.input[l.start:l.pos], l.startLine}
   166  	l.start = l.pos
   167  	l.startLine = l.line
   168  }
   169  
   170  // ignore skips over the pending input before this point.
   171  func (l *lexer) ignore() {
   172  	l.line += strings.Count(l.input[l.start:l.pos], "\n")
   173  	l.start = l.pos
   174  	l.startLine = l.line
   175  }
   176  
   177  // accept consumes the next rune if it's from the valid set.
   178  func (l *lexer) accept(valid string) bool {
   179  	if strings.ContainsRune(valid, l.next()) {
   180  		return true
   181  	}
   182  	l.backup()
   183  	return false
   184  }
   185  
   186  // acceptRun consumes a run of runes from the valid set.
   187  func (l *lexer) acceptRun(valid string) {
   188  	for strings.ContainsRune(valid, l.next()) {
   189  	}
   190  	l.backup()
   191  }
   192  
   193  // errorf returns an error token and terminates the scan by passing
   194  // back a nil pointer that will be the next state, terminating l.nextItem.
   195  func (l *lexer) errorf(format string, args ...any) stateFn {
   196  	l.items <- item{itemError, l.start, fmt.Sprintf(format, args...), l.startLine}
   197  	return nil
   198  }
   199  
   200  // nextItem returns the next item from the input.
   201  // Called by the parser, not in the lexing goroutine.
   202  func (l *lexer) nextItem() item {
   203  	return <-l.items
   204  }
   205  
   206  // drain drains the output so the lexing goroutine will exit.
   207  // Called by the parser, not in the lexing goroutine.
   208  func (l *lexer) drain() {
   209  	for range l.items {
   210  	}
   211  }
   212  
   213  // lex creates a new scanner for the input string.
   214  func lex(name, input, left, right string, emitComment, breakOK, continueOK bool) *lexer {
   215  	if left == "" {
   216  		left = leftDelim
   217  	}
   218  	if right == "" {
   219  		right = rightDelim
   220  	}
   221  	l := &lexer{
   222  		name:        name,
   223  		input:       input,
   224  		leftDelim:   left,
   225  		rightDelim:  right,
   226  		emitComment: emitComment,
   227  		breakOK:     breakOK,
   228  		continueOK:  continueOK,
   229  		items:       make(chan item),
   230  		line:        1,
   231  		startLine:   1,
   232  	}
   233  	go l.run()
   234  	return l
   235  }
   236  
   237  // run runs the state machine for the lexer.
   238  func (l *lexer) run() {
   239  	for state := lexText; state != nil; {
   240  		state = state(l)
   241  	}
   242  	close(l.items)
   243  }
   244  
   245  // state functions
   246  
   247  const (
   248  	leftDelim    = "{{"
   249  	rightDelim   = "}}"
   250  	leftComment  = "/*"
   251  	rightComment = "*/"
   252  )
   253  
   254  // lexText scans until an opening action delimiter, "{{".
   255  func lexText(l *lexer) stateFn {
   256  	if x := strings.Index(l.input[l.pos:], l.leftDelim); x >= 0 {
   257  		ldn := Pos(len(l.leftDelim))
   258  		l.pos += Pos(x)
   259  		trimLength := Pos(0)
   260  		if hasLeftTrimMarker(l.input[l.pos+ldn:]) {
   261  			trimLength = rightTrimLength(l.input[l.start:l.pos])
   262  		}
   263  		l.pos -= trimLength
   264  		if l.pos > l.start {
   265  			l.line += strings.Count(l.input[l.start:l.pos], "\n")
   266  			l.emit(itemText)
   267  		}
   268  		l.pos += trimLength
   269  		l.ignore()
   270  		return lexLeftDelim
   271  	}
   272  	l.pos = Pos(len(l.input))
   273  	// Correctly reached EOF.
   274  	if l.pos > l.start {
   275  		l.line += strings.Count(l.input[l.start:l.pos], "\n")
   276  		l.emit(itemText)
   277  	}
   278  	l.emit(itemEOF)
   279  	return nil
   280  }
   281  
   282  // rightTrimLength returns the length of the spaces at the end of the string.
   283  func rightTrimLength(s string) Pos {
   284  	return Pos(len(s) - len(strings.TrimRight(s, spaceChars)))
   285  }
   286  
   287  // atRightDelim reports whether the lexer is at a right delimiter, possibly preceded by a trim marker.
   288  func (l *lexer) atRightDelim() (delim, trimSpaces bool) {
   289  	if hasRightTrimMarker(l.input[l.pos:]) && strings.HasPrefix(l.input[l.pos+trimMarkerLen:], l.rightDelim) { // With trim marker.
   290  		return true, true
   291  	}
   292  	if strings.HasPrefix(l.input[l.pos:], l.rightDelim) { // Without trim marker.
   293  		return true, false
   294  	}
   295  	return false, false
   296  }
   297  
   298  // leftTrimLength returns the length of the spaces at the beginning of the string.
   299  func leftTrimLength(s string) Pos {
   300  	return Pos(len(s) - len(strings.TrimLeft(s, spaceChars)))
   301  }
   302  
   303  // lexLeftDelim scans the left delimiter, which is known to be present, possibly with a trim marker.
   304  func lexLeftDelim(l *lexer) stateFn {
   305  	l.pos += Pos(len(l.leftDelim))
   306  	trimSpace := hasLeftTrimMarker(l.input[l.pos:])
   307  	afterMarker := Pos(0)
   308  	if trimSpace {
   309  		afterMarker = trimMarkerLen
   310  	}
   311  	if strings.HasPrefix(l.input[l.pos+afterMarker:], leftComment) {
   312  		l.pos += afterMarker
   313  		l.ignore()
   314  		return lexComment
   315  	}
   316  	l.emit(itemLeftDelim)
   317  	l.pos += afterMarker
   318  	l.ignore()
   319  	l.parenDepth = 0
   320  	return lexInsideAction
   321  }
   322  
   323  // lexComment scans a comment. The left comment marker is known to be present.
   324  func lexComment(l *lexer) stateFn {
   325  	l.pos += Pos(len(leftComment))
   326  	i := strings.Index(l.input[l.pos:], rightComment)
   327  	if i < 0 {
   328  		return l.errorf("unclosed comment")
   329  	}
   330  	l.pos += Pos(i + len(rightComment))
   331  	delim, trimSpace := l.atRightDelim()
   332  	if !delim {
   333  		return l.errorf("comment ends before closing delimiter")
   334  	}
   335  	if l.emitComment {
   336  		l.emit(itemComment)
   337  	}
   338  	if trimSpace {
   339  		l.pos += trimMarkerLen
   340  	}
   341  	l.pos += Pos(len(l.rightDelim))
   342  	if trimSpace {
   343  		l.pos += leftTrimLength(l.input[l.pos:])
   344  	}
   345  	l.ignore()
   346  	return lexText
   347  }
   348  
   349  // lexRightDelim scans the right delimiter, which is known to be present, possibly with a trim marker.
   350  func lexRightDelim(l *lexer) stateFn {
   351  	trimSpace := hasRightTrimMarker(l.input[l.pos:])
   352  	if trimSpace {
   353  		l.pos += trimMarkerLen
   354  		l.ignore()
   355  	}
   356  	l.pos += Pos(len(l.rightDelim))
   357  	l.emit(itemRightDelim)
   358  	if trimSpace {
   359  		l.pos += leftTrimLength(l.input[l.pos:])
   360  		l.ignore()
   361  	}
   362  	return lexText
   363  }
   364  
   365  // lexInsideAction scans the elements inside action delimiters.
   366  func lexInsideAction(l *lexer) stateFn {
   367  	// Either number, quoted string, or identifier.
   368  	// Spaces separate arguments; runs of spaces turn into itemSpace.
   369  	// Pipe symbols separate and are emitted.
   370  	delim, _ := l.atRightDelim()
   371  	if delim {
   372  		if l.parenDepth == 0 {
   373  			return lexRightDelim
   374  		}
   375  		return l.errorf("unclosed left paren")
   376  	}
   377  	switch r := l.next(); {
   378  	case r == eof:
   379  		return l.errorf("unclosed action")
   380  	case isSpace(r):
   381  		l.backup() // Put space back in case we have " -}}".
   382  		return lexSpace
   383  	case r == '=':
   384  		l.emit(itemAssign)
   385  	case r == ':':
   386  		if l.next() != '=' {
   387  			return l.errorf("expected :=")
   388  		}
   389  		l.emit(itemDeclare)
   390  	case r == '|':
   391  		l.emit(itemPipe)
   392  	case r == '"':
   393  		return lexQuote
   394  	case r == '`':
   395  		return lexRawQuote
   396  	case r == '$':
   397  		return lexVariable
   398  	case r == '\'':
   399  		return lexChar
   400  	case r == '.':
   401  		// special look-ahead for ".field" so we don't break l.backup().
   402  		if l.pos < Pos(len(l.input)) {
   403  			r := l.input[l.pos]
   404  			if r < '0' || '9' < r {
   405  				return lexField
   406  			}
   407  		}
   408  		fallthrough // '.' can start a number.
   409  	case r == '+' || r == '-' || ('0' <= r && r <= '9'):
   410  		l.backup()
   411  		return lexNumber
   412  	case isAlphaNumeric(r):
   413  		l.backup()
   414  		return lexIdentifier
   415  	case r == '(':
   416  		l.emit(itemLeftParen)
   417  		l.parenDepth++
   418  	case r == ')':
   419  		l.emit(itemRightParen)
   420  		l.parenDepth--
   421  		if l.parenDepth < 0 {
   422  			return l.errorf("unexpected right paren %#U", r)
   423  		}
   424  	case r <= unicode.MaxASCII && unicode.IsPrint(r):
   425  		l.emit(itemChar)
   426  	default:
   427  		return l.errorf("unrecognized character in action: %#U", r)
   428  	}
   429  	return lexInsideAction
   430  }
   431  
   432  // lexSpace scans a run of space characters.
   433  // We have not consumed the first space, which is known to be present.
   434  // Take care if there is a trim-marked right delimiter, which starts with a space.
   435  func lexSpace(l *lexer) stateFn {
   436  	var r rune
   437  	var numSpaces int
   438  	for {
   439  		r = l.peek()
   440  		if !isSpace(r) {
   441  			break
   442  		}
   443  		l.next()
   444  		numSpaces++
   445  	}
   446  	// Be careful about a trim-marked closing delimiter, which has a minus
   447  	// after a space. We know there is a space, so check for the '-' that might follow.
   448  	if hasRightTrimMarker(l.input[l.pos-1:]) && strings.HasPrefix(l.input[l.pos-1+trimMarkerLen:], l.rightDelim) {
   449  		l.backup() // Before the space.
   450  		if numSpaces == 1 {
   451  			return lexRightDelim // On the delim, so go right to that.
   452  		}
   453  	}
   454  	l.emit(itemSpace)
   455  	return lexInsideAction
   456  }
   457  
   458  // lexIdentifier scans an alphanumeric.
   459  func lexIdentifier(l *lexer) stateFn {
   460  Loop:
   461  	for {
   462  		switch r := l.next(); {
   463  		case isAlphaNumeric(r):
   464  			// absorb.
   465  		default:
   466  			l.backup()
   467  			word := l.input[l.start:l.pos]
   468  			if !l.atTerminator() {
   469  				return l.errorf("bad character %#U", r)
   470  			}
   471  			switch {
   472  			case key[word] > itemKeyword:
   473  				item := key[word]
   474  				if item == itemBreak && !l.breakOK || item == itemContinue && !l.continueOK {
   475  					l.emit(itemIdentifier)
   476  				} else {
   477  					l.emit(item)
   478  				}
   479  			case word[0] == '.':
   480  				l.emit(itemField)
   481  			case word == "true", word == "false":
   482  				l.emit(itemBool)
   483  			default:
   484  				l.emit(itemIdentifier)
   485  			}
   486  			break Loop
   487  		}
   488  	}
   489  	return lexInsideAction
   490  }
   491  
   492  // lexField scans a field: .Alphanumeric.
   493  // The . has been scanned.
   494  func lexField(l *lexer) stateFn {
   495  	return lexFieldOrVariable(l, itemField)
   496  }
   497  
   498  // lexVariable scans a Variable: $Alphanumeric.
   499  // The $ has been scanned.
   500  func lexVariable(l *lexer) stateFn {
   501  	if l.atTerminator() { // Nothing interesting follows -> "$".
   502  		l.emit(itemVariable)
   503  		return lexInsideAction
   504  	}
   505  	return lexFieldOrVariable(l, itemVariable)
   506  }
   507  
   508  // lexVariable scans a field or variable: [.$]Alphanumeric.
   509  // The . or $ has been scanned.
   510  func lexFieldOrVariable(l *lexer, typ itemType) stateFn {
   511  	if l.atTerminator() { // Nothing interesting follows -> "." or "$".
   512  		if typ == itemVariable {
   513  			l.emit(itemVariable)
   514  		} else {
   515  			l.emit(itemDot)
   516  		}
   517  		return lexInsideAction
   518  	}
   519  	var r rune
   520  	for {
   521  		r = l.next()
   522  		if !isAlphaNumeric(r) {
   523  			l.backup()
   524  			break
   525  		}
   526  	}
   527  	if !l.atTerminator() {
   528  		return l.errorf("bad character %#U", r)
   529  	}
   530  	l.emit(typ)
   531  	return lexInsideAction
   532  }
   533  
   534  // atTerminator reports whether the input is at valid termination character to
   535  // appear after an identifier. Breaks .X.Y into two pieces. Also catches cases
   536  // like "$x+2" not being acceptable without a space, in case we decide one
   537  // day to implement arithmetic.
   538  func (l *lexer) atTerminator() bool {
   539  	r := l.peek()
   540  	if isSpace(r) {
   541  		return true
   542  	}
   543  	switch r {
   544  	case eof, '.', ',', '|', ':', ')', '(':
   545  		return true
   546  	}
   547  	return strings.HasPrefix(l.input[l.pos:], l.rightDelim)
   548  }
   549  
   550  // lexChar scans a character constant. The initial quote is already
   551  // scanned. Syntax checking is done by the parser.
   552  func lexChar(l *lexer) stateFn {
   553  Loop:
   554  	for {
   555  		switch l.next() {
   556  		case '\\':
   557  			if r := l.next(); r != eof && r != '\n' {
   558  				break
   559  			}
   560  			fallthrough
   561  		case eof, '\n':
   562  			return l.errorf("unterminated character constant")
   563  		case '\'':
   564  			break Loop
   565  		}
   566  	}
   567  	l.emit(itemCharConstant)
   568  	return lexInsideAction
   569  }
   570  
   571  // lexNumber scans a number: decimal, octal, hex, float, or imaginary. This
   572  // isn't a perfect number scanner - for instance it accepts "." and "0x0.2"
   573  // and "089" - but when it's wrong the input is invalid and the parser (via
   574  // strconv) will notice.
   575  func lexNumber(l *lexer) stateFn {
   576  	if !l.scanNumber() {
   577  		return l.errorf("bad number syntax: %q", l.input[l.start:l.pos])
   578  	}
   579  	if sign := l.peek(); sign == '+' || sign == '-' {
   580  		// Complex: 1+2i. No spaces, must end in 'i'.
   581  		if !l.scanNumber() || l.input[l.pos-1] != 'i' {
   582  			return l.errorf("bad number syntax: %q", l.input[l.start:l.pos])
   583  		}
   584  		l.emit(itemComplex)
   585  	} else {
   586  		l.emit(itemNumber)
   587  	}
   588  	return lexInsideAction
   589  }
   590  
   591  func (l *lexer) scanNumber() bool {
   592  	// Optional leading sign.
   593  	l.accept("+-")
   594  	// Is it hex?
   595  	digits := "0123456789_"
   596  	if l.accept("0") {
   597  		// Note: Leading 0 does not mean octal in floats.
   598  		if l.accept("xX") {
   599  			digits = "0123456789abcdefABCDEF_"
   600  		} else if l.accept("oO") {
   601  			digits = "01234567_"
   602  		} else if l.accept("bB") {
   603  			digits = "01_"
   604  		}
   605  	}
   606  	l.acceptRun(digits)
   607  	if l.accept(".") {
   608  		l.acceptRun(digits)
   609  	}
   610  	if len(digits) == 10+1 && l.accept("eE") {
   611  		l.accept("+-")
   612  		l.acceptRun("0123456789_")
   613  	}
   614  	if len(digits) == 16+6+1 && l.accept("pP") {
   615  		l.accept("+-")
   616  		l.acceptRun("0123456789_")
   617  	}
   618  	// Is it imaginary?
   619  	l.accept("i")
   620  	// Next thing mustn't be alphanumeric.
   621  	if isAlphaNumeric(l.peek()) {
   622  		l.next()
   623  		return false
   624  	}
   625  	return true
   626  }
   627  
   628  // lexQuote scans a quoted string.
   629  func lexQuote(l *lexer) stateFn {
   630  Loop:
   631  	for {
   632  		switch l.next() {
   633  		case '\\':
   634  			if r := l.next(); r != eof && r != '\n' {
   635  				break
   636  			}
   637  			fallthrough
   638  		case eof, '\n':
   639  			return l.errorf("unterminated quoted string")
   640  		case '"':
   641  			break Loop
   642  		}
   643  	}
   644  	l.emit(itemString)
   645  	return lexInsideAction
   646  }
   647  
   648  // lexRawQuote scans a raw quoted string.
   649  func lexRawQuote(l *lexer) stateFn {
   650  Loop:
   651  	for {
   652  		switch l.next() {
   653  		case eof:
   654  			return l.errorf("unterminated raw quoted string")
   655  		case '`':
   656  			break Loop
   657  		}
   658  	}
   659  	l.emit(itemRawString)
   660  	return lexInsideAction
   661  }
   662  
   663  // isSpace reports whether r is a space character.
   664  func isSpace(r rune) bool {
   665  	return r == ' ' || r == '\t' || r == '\r' || r == '\n'
   666  }
   667  
   668  // isAlphaNumeric reports whether r is an alphabetic, digit, or underscore.
   669  func isAlphaNumeric(r rune) bool {
   670  	return r == '_' || unicode.IsLetter(r) || unicode.IsDigit(r)
   671  }
   672  
   673  func hasLeftTrimMarker(s string) bool {
   674  	return len(s) >= 2 && s[0] == trimMarker && isSpace(rune(s[1]))
   675  }
   676  
   677  func hasRightTrimMarker(s string) bool {
   678  	return len(s) >= 2 && isSpace(rune(s[0])) && s[1] == trimMarker
   679  }
   680
View as plain text