// intersperseComments consumes all comments that appear before the next token
// tok and prints it together with the buffered whitespace (i.e., the whitespace
// that needs to be written before the next token). A heuristic is used to mix
// the comments and whitespace. The intersperseComments result indicates if a
// newline was written or if a formfeed was dropped from the whitespace buffer.
//
func (p *printer) intersperseComments(next token.Position, tok token.Token) (wroteNewline, droppedFF bool) {
var last *ast.Comment
for p.commentBefore(next) {
for _, c := range p.comment.List {
p.writeCommentPrefix(p.posFor(c.Pos()), next, last, c, tok)
p.writeComment(c)
last = c
}
p.nextComment()
}
if last != nil {
// if the last comment is a /*-style comment and the next item
// follows on the same line but is not a comma or a "closing"
// token, add an extra blank for separation
if last.Text[1] == '*' && p.lineFor(last.Pos()) == next.Line && tok != token.COMMA &&
tok != token.RPAREN && tok != token.RBRACK && tok != token.RBRACE {
p.writeByte(' ', 1)
}
// ensure that there is a line break after a //-style comment,
// before a closing '}' unless explicitly disabled, or at eof
needsLinebreak :=
last.Text[1] == '/' ||
tok == token.RBRACE && p.mode&noExtraLinebreak == 0 ||
tok == token.EOF
return p.writeCommentSuffix(needsLinebreak)
}
// no comment was written - we should never reach here since
// intersperseComments should not be called in that case
p.internalError("intersperseComments called without pending comments")
return
}
func (p *printer) writeComment(comment *ast.Comment) {
text := comment.Text
pos := p.posFor(comment.Pos())
const linePrefix = "//line "
if strings.HasPrefix(text, linePrefix) && (!pos.IsValid() || pos.Column == 1) {
// possibly a line directive
ldir := strings.TrimSpace(text[len(linePrefix):])
if i := strings.LastIndex(ldir, ":"); i >= 0 {
if line, err := strconv.Atoi(ldir[i+1:]); err == nil && line > 0 {
// The line directive we are about to print changed
// the Filename and Line number used for subsequent
// tokens. We have to update our AST-space position
// accordingly and suspend indentation temporarily.
indent := p.indent
p.indent = 0
defer func() {
p.pos.Filename = ldir[:i]
p.pos.Line = line
p.pos.Column = 1
p.indent = indent
}()
}
}
}
// shortcut common case of //-style comments
if text[1] == '/' {
p.writeString(pos, trimRight(text), true)
return
}
// for /*-style comments, print line by line and let the
// write function take care of the proper indentation
lines := strings.Split(text, "\n")
// The comment started in the first column but is going
// to be indented. For an idempotent result, add indentation
// to all lines such that they look like they were indented
// before - this will make sure the common prefix computation
// is the same independent of how many times formatting is
// applied (was issue 1835).
if pos.IsValid() && pos.Column == 1 && p.indent > 0 {
for i, line := range lines[1:] {
lines[1+i] = " " + line
}
}
stripCommonPrefix(lines)
// write comment lines, separated by formfeed,
// without a line break after the last line
for i, line := range lines {
if i > 0 {
p.writeByte('\f', 1)
pos = p.pos
}
if len(line) > 0 {
p.writeString(pos, trimRight(line), true)
}
}
}