diff options
Diffstat (limited to 'src/pkg/go/printer/printer.go')
| -rw-r--r-- | src/pkg/go/printer/printer.go | 125 |
1 files changed, 93 insertions, 32 deletions
diff --git a/src/pkg/go/printer/printer.go b/src/pkg/go/printer/printer.go index e06d2edfb..280c697a0 100644 --- a/src/pkg/go/printer/printer.go +++ b/src/pkg/go/printer/printer.go @@ -39,9 +39,17 @@ const ( type pmode int const ( - noExtraLinebreak pmode = 1 << iota + noExtraBlank pmode = 1 << iota // disables extra blank after /*-style comment + noExtraLinebreak // disables extra line break after /*-style comment ) +type commentInfo struct { + cindex int // current comment index + comment *ast.CommentGroup // = printer.comments[cindex]; or nil + commentOffset int // = printer.posFor(printer.comments[cindex].List[0].Pos()).Offset; or infinity + commentNewline bool // true if the comment group contains newlines +} + type printer struct { // Configuration (does not change after initialization) Config @@ -52,7 +60,8 @@ type printer struct { indent int // current indentation mode pmode // current printer mode impliedSemi bool // if set, a linebreak implies a semicolon - lastTok token.Token // the last token printed (token.ILLEGAL if it's whitespace) + lastTok token.Token // last token printed (token.ILLEGAL if it's whitespace) + prevOpen token.Token // previous non-brace "open" token (, [, or token.ILLEGAL wsbuf []whiteSpace // delayed white space // Positions @@ -61,19 +70,17 @@ type printer struct { // white space). If there's a difference and SourcePos is set in // ConfigMode, //line comments are used in the output to restore // original source positions for a reader. - pos token.Position // current position in AST (source) space - out token.Position // current position in output space - last token.Position // value of pos after calling writeString + pos token.Position // current position in AST (source) space + out token.Position // current position in output space + last token.Position // value of pos after calling writeString + linePtr *int // if set, record out.Line for the next token in *linePtr // The list of all source comments, in order of appearance. comments []*ast.CommentGroup // may be nil - cindex int // current comment index useNodeComments bool // if not set, ignore lead and line comments of nodes // Information about p.comments[p.cindex]; set up by nextComment. - comment *ast.CommentGroup // = p.comments[p.cindex]; or nil - commentOffset int // = p.posFor(p.comments[p.cindex].List[0].Pos()).Offset; or infinity - commentNewline bool // true if the comment group contains newlines + commentInfo // Cache of already computed node sizes. nodeSizes map[ast.Node]int @@ -93,6 +100,14 @@ func (p *printer) init(cfg *Config, fset *token.FileSet, nodeSizes map[ast.Node] p.cachedPos = -1 } +func (p *printer) internalError(msg ...interface{}) { + if debug { + fmt.Print(p.pos.String() + ": ") + fmt.Println(msg...) + panic("go/printer") + } +} + // commentsHaveNewline reports whether a list of comments belonging to // an *ast.CommentGroup contains newlines. Because the position information // may only be partially correct, we also have to read the comment text. @@ -129,12 +144,49 @@ func (p *printer) nextComment() { p.commentOffset = infinity } -func (p *printer) internalError(msg ...interface{}) { - if debug { - fmt.Print(p.pos.String() + ": ") - fmt.Println(msg...) - panic("go/printer") +// commentBefore returns true iff the current comment group occurs +// before the next position in the source code and printing it does +// not introduce implicit semicolons. +// +func (p *printer) commentBefore(next token.Position) bool { + return p.commentOffset < next.Offset && (!p.impliedSemi || !p.commentNewline) +} + +// commentSizeBefore returns the estimated size of the +// comments on the same line before the next position. +// +func (p *printer) commentSizeBefore(next token.Position) int { + // save/restore current p.commentInfo (p.nextComment() modifies it) + defer func(info commentInfo) { + p.commentInfo = info + }(p.commentInfo) + + size := 0 + for p.commentBefore(next) { + for _, c := range p.comment.List { + size += len(c.Text) + } + p.nextComment() } + return size +} + +// recordLine records the output line number for the next non-whitespace +// token in *linePtr. It is used to compute an accurate line number for a +// formatted construct, independent of pending (not yet emitted) whitespace +// or comments. +// +func (p *printer) recordLine(linePtr *int) { + p.linePtr = linePtr +} + +// linesFrom returns the number of output lines between the current +// output line and the line argument, ignoring any pending (not yet +// emitted) whitespace or comments. It is used to compute an accurate +// size (in number of lines) for a formatted construct. +// +func (p *printer) linesFrom(line int) int { + return p.out.Line - line } func (p *printer) posFor(pos token.Pos) token.Position { @@ -675,10 +727,14 @@ func (p *printer) intersperseComments(next token.Position, tok token.Token) (wro 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 { + // follows on the same line but is not a comma, and not a "closing" + // token immediately following its corresponding "opening" token, + // add an extra blank for separation unless explicitly disabled + 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) { p.writeByte(' ', 1) } // ensure that there is a line break after a //-style comment, @@ -735,12 +791,8 @@ func (p *printer) writeWhitespace(n int) { } // shift remaining entries down - i := 0 - for ; n < len(p.wsbuf); n++ { - p.wsbuf[i] = p.wsbuf[n] - i++ - } - p.wsbuf = p.wsbuf[0:i] + l := copy(p.wsbuf, p.wsbuf[n:]) + p.wsbuf = p.wsbuf[:l] } // ---------------------------------------------------------------------------- @@ -790,6 +842,17 @@ func (p *printer) print(args ...interface{}) { var isLit bool var impliedSemi bool // value for p.impliedSemi after this arg + // record previous opening token, if any + switch p.lastTok { + case token.ILLEGAL: + // ignore (white space) + case token.LPAREN, token.LBRACK: + p.prevOpen = p.lastTok + default: + // other tokens followed any opening token + p.prevOpen = token.ILLEGAL + } + switch x := arg.(type) { case pmode: // toggle printer mode @@ -899,19 +962,17 @@ func (p *printer) print(args ...interface{}) { } } + // the next token starts now - record its line number if requested + if p.linePtr != nil { + *p.linePtr = p.out.Line + p.linePtr = nil + } + p.writeString(next, data, isLit) p.impliedSemi = impliedSemi } } -// commentBefore returns true iff the current comment group occurs -// before the next position in the source code and printing it does -// not introduce implicit semicolons. -// -func (p *printer) commentBefore(next token.Position) (result bool) { - return p.commentOffset < next.Offset && (!p.impliedSemi || !p.commentNewline) -} - // flush prints any pending comments and whitespace occurring textually // before the position of the next token tok. The flush result indicates // if a newline was written or if a formfeed was dropped from the whitespace |