Golang Comment.Pos方法代码示例

// 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
}

// 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. intersperseComments returns true if a pending
// formfeed was dropped from the whitespace buffer.
//
func (p *printer) intersperseComments(next token.Position, tok token.Token) (droppedFF bool) {
	var last *ast.Comment
	for ; p.commentBefore(next); p.cindex++ {
		for _, c := range p.comments[p.cindex].List {
			p.writeCommentPrefix(p.fset.Position(c.Pos()), next, last, tok.IsKeyword())
			p.writeComment(c)
			last = c
		}
	}

	if last != nil {
		if last.Text[1] == '*' && p.fset.Position(last.Pos()).Line == next.Line {
			// the last comment is a /*-style comment and the next item
			// follows on the same line: separate with an extra blank
			p.write([]byte{' '})
		}
		// 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 false
}

func (p *printer) writeComment(comment *ast.Comment) {
	text := comment.Text

	// shortcut common case of //-style comments
	if text[1] == '/' {
		p.writeItem(p.fset.Position(comment.Pos()), p.escape(text))
		return
	}

	// for /*-style comments, print line by line and let the
	// write function take care of the proper indentation
	lines := split([]byte(text))
	stripCommonPrefix(lines)

	// write comment lines, separated by formfeed,
	// without a line break after the last line
	linebreak := formfeeds[0:1]
	pos := p.fset.Position(comment.Pos())
	for i, line := range lines {
		if i > 0 {
			p.write(linebreak)
			pos = p.pos
		}
		if len(line) > 0 {
			p.writeItem(pos, p.escape(string(line)))
		}
	}
}

// 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. intersperseComments returns true if a pending
// formfeed was dropped from the whitespace buffer.
//
func (p *printer) intersperseComments(next token.Position, tok token.Token) (droppedFF bool) {
	var last *ast.Comment
	for ; p.commentBefore(next); p.cindex++ {
		for _, c := range p.comments[p.cindex].List {
			p.writeCommentPrefix(c.Pos(), next, last == nil, tok.IsKeyword())
			p.writeComment(c)
			last = c
		}
	}

	if last != nil {
		if last.Text[1] == '*' && last.Pos().Line == next.Line {
			// the last comment is a /*-style comment and the next item
			// follows on the same line: separate with an extra blank
			p.write([]byte{' '})
		}
		// ensure that there is a newline after a //-style comment
		// or if we are before a closing '}' or at the end of a file
		return p.writeCommentSuffix(last.Text[1] == '/' || tok == token.RBRACE || tok == token.EOF)
	}

	// 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 false
}

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, text, true)
		return
	}

	// for /*-style comments, print line by line and let the
	// write function take care of the proper indentation
	lines := split(text)
	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, line, true)
		}
	}
}

// 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, and not a "closing"
		// token immediately following its corresponding "opening" token,
		// add an extra separator unless explicitly disabled. Use a blank
		// as separator unless we have pending linebreaks and they are not
		// disabled, in which case we want a linebreak (issue 15137).
		needsLinebreak := false
		if p.mode&noExtraBlank == 0 &&
			last.Text[1] == '*' && p.lineFor(last.Pos()) == next.Line &&
			tok != token.COMMA &&
			(tok != token.RPAREN || p.prevOpen == token.LPAREN) &&
			(tok != token.RBRACK || p.prevOpen == token.LBRACK) {
			if p.containsLinebreak() && p.mode&noExtraLinebreak == 0 {
				needsLinebreak = true
			} else {
				p.writeByte(' ', 1)
			}
		}
		// Ensure that there is a line break after a //-style comment,
		// before EOF, and before a closing '}' unless explicitly disabled.
		if last.Text[1] == '/' ||
			tok == token.EOF ||
			tok == token.RBRACE && p.mode&noExtraLinebreak == 0 {
			needsLinebreak = true
		}
		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)
		}
	}
}