text/template: add CommentNode to template parse tree

Fixes #34652

Change-Id: Icf6e3eda593fed826736f34f95a9d66f5450cc98
Reviewed-on: https://go-review.googlesource.com/c/go/+/229398
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/src/text/template/parse/lex.go b/src/text/template/parse/lex.go
index 30371f2862..e41373a002 100644
--- a/src/text/template/parse/lex.go
+++ b/src/text/template/parse/lex.go
@@ -41,6 +41,7 @@ const (
 	itemBool                         // boolean constant
 	itemChar                         // printable ASCII character; grab bag for comma etc.
 	itemCharConstant                 // character constant
+	itemComment                      // comment text
 	itemComplex                      // complex constant (1+2i); imaginary is just a number
 	itemAssign                       // equals ('=') introducing an assignment
 	itemDeclare                      // colon-equals (':=') introducing a declaration
@@ -112,6 +113,7 @@ type lexer struct {
 	leftDelim      string    // start of action
 	rightDelim     string    // end of action
 	trimRightDelim string    // end of action with trim marker
+	emitComment    bool      // emit itemComment tokens.
 	pos            Pos       // current position in the input
 	start          Pos       // start position of this item
 	width          Pos       // width of last rune read from input
@@ -203,7 +205,7 @@ func (l *lexer) drain() {
 }
 
 // lex creates a new scanner for the input string.
-func lex(name, input, left, right string) *lexer {
+func lex(name, input, left, right string, emitComment bool) *lexer {
 	if left == "" {
 		left = leftDelim
 	}
@@ -216,6 +218,7 @@ func lex(name, input, left, right string) *lexer {
 		leftDelim:      left,
 		rightDelim:     right,
 		trimRightDelim: rightTrimMarker + right,
+		emitComment:    emitComment,
 		items:          make(chan item),
 		line:           1,
 		startLine:      1,
@@ -323,6 +326,9 @@ func lexComment(l *lexer) stateFn {
 	if !delim {
 		return l.errorf("comment ends before closing delimiter")
 	}
+	if l.emitComment {
+		l.emit(itemComment)
+	}
 	if trimSpace {
 		l.pos += trimMarkerLen
 	}