"go/token"
)
-
// Other formatting issues:
// - better comment formatting for /*-style comments at the end of a line (e.g. a declaration)
// when the comment spans multiple lines; if such a comment is just two lines, formatting is
// - should use blank instead of tab to separate one-line function bodies from
// the function header unless there is a group of consecutive one-liners
-
// ----------------------------------------------------------------------------
// Common AST nodes.
// line break was printed; returns false otherwise.
//
// TODO(gri): linebreak may add too many lines if the next statement at "line"
-// is preceeded by comments because the computation of n assumes
+// is preceded by comments because the computation of n assumes
// the current position before the comment and the target position
// after the comment. Thus, after interspersing such comments, the
// space taken up by them is not considered to reduce the number of
return
}
-
// setComment sets g as the next comment if g != nil and if node comments
// are enabled - this mode is used when printing source code fragments such
// as exports only. It assumes that there are no other pending comments to
p.cindex = 0
}
-
type exprListMode uint
const (
periodSep // elements are separated by periods
)
-
// Sets multiLine to true if the identifier list spans multiple lines.
// If indent is set, a multi-line identifier list is indented after the
// first linebreak encountered.
p.exprList(token.NoPos, xlist, 1, mode, multiLine, token.NoPos)
}
-
// Print a list of expressions. If the list spans multiple
// source lines, the original line breaks are respected between
// expressions. Sets multiLine to true if the list spans multiple
// the first linebreak is always a formfeed since this section must not
// depend on any previous formatting
prevBreak := -1 // index of last expression that was followed by a linebreak
- linebreakMin := 1
- if mode&periodSep != 0 {
- // Make fragments like
- //
- // a.Bar(1,
- // 2).Foo
- //
- // format correctly (a linebreak shouldn't be added before Foo) when
- // doing period-separated expr lists by setting minimum linebreak to 0
- // lines for them.
- linebreakMin = 0
- }
- if prev.IsValid() && prev.Line < line && p.linebreak(line, linebreakMin, ws, true) {
+ if prev.IsValid() && prev.Line < line && p.linebreak(line, 0, ws, true) {
ws = ignore
*multiLine = true
prevBreak = 0
}
if i > 0 {
- if mode&commaSep != 0 {
+ switch {
+ case mode&commaSep != 0:
p.print(token.COMMA)
- }
- if mode&periodSep != 0 {
+ case mode&periodSep != 0:
p.print(token.PERIOD)
}
+ needsBlank := mode&periodSep == 0 // period-separated list elements don't need a blank
if prevLine < line && prevLine > 0 && line > 0 {
// lines are broken using newlines so comments remain aligned
// unless forceFF is set or there are multiple expressions on
// the same line in which case formfeed is used
- if p.linebreak(line, linebreakMin, ws, useFF || prevBreak+1 < i) {
+ if p.linebreak(line, 0, ws, useFF || prevBreak+1 < i) {
ws = ignore
*multiLine = true
prevBreak = i
+ needsBlank = false // we got a line break instead
}
- } else if mode&periodSep == 0 {
+ }
+ if needsBlank {
p.print(blank)
}
- // period-separated list elements don't need a blank
}
if isPair && size > 0 && len(list) > 1 {
}
}
-
// Sets multiLine to true if the the parameter list spans multiple lines.
func (p *printer) parameters(fields *ast.FieldList, multiLine *bool) {
p.print(fields.Opening, token.LPAREN)
if len(fields.List) > 0 {
+ ws := indent
var prevLine, line int
for i, par := range fields.List {
if i > 0 {
} else {
line = p.fset.Position(par.Type.Pos()).Line
}
- if 0 < prevLine && prevLine < line && p.linebreak(line, 0, ignore, true) {
+ if 0 < prevLine && prevLine < line && p.linebreak(line, 0, ws, true) {
+ ws = ignore
*multiLine = true
} else {
p.print(blank)
}
}
if len(par.Names) > 0 {
- p.identList(par.Names, false, multiLine)
+ // Very subtle: If we indented before (ws == ignore), identList
+ // won't indent again. If we didn't (ws == indent), identList will
+ // indent if the identList spans multiple lines, and it will outdent
+ // again at the end (and still ws == indent). Thus, a subsequent indent
+ // by a linebreak call after a type, or in the next multi-line identList
+ // will do the right thing.
+ p.identList(par.Names, ws == indent, multiLine)
p.print(blank)
}
p.expr(par.Type, multiLine)
prevLine = p.fset.Position(par.Type.Pos()).Line
}
+ if ws == ignore {
+ // unindent if we indented
+ p.print(unindent)
+ }
}
p.print(fields.Closing, token.RPAREN)
}
-
// Sets multiLine to true if the signature spans multiple lines.
func (p *printer) signature(params, result *ast.FieldList, multiLine *bool) {
p.parameters(params, multiLine)
}
}
-
func identListSize(list []*ast.Ident, maxSize int) (size int) {
for i, x := range list {
if i > 0 {
return
}
-
func (p *printer) isOneLineFieldList(list []*ast.Field) bool {
if len(list) != 1 {
return false // allow only one field
return namesSize+typeSize <= maxSize
}
-
func (p *printer) setLineComment(text string) {
- p.setComment(&ast.CommentGroup{[]*ast.Comment{&ast.Comment{token.NoPos, []byte(text)}}})
+ p.setComment(&ast.CommentGroup{[]*ast.Comment{{token.NoPos, text}}})
}
-
func (p *printer) fieldList(fields *ast.FieldList, isStruct, isIncomplete bool) {
- p.nesting++
- defer func() {
- p.nesting--
- }()
-
lbrace := fields.Opening
list := fields.List
rbrace := fields.Closing
if len(list) > 0 {
p.print(formfeed)
}
- p.flush(p.fset.Position(rbrace), token.RBRACE) // make sure we don't loose the last line comment
- p.setLineComment("// contains unexported fields")
+ p.flush(p.fset.Position(rbrace), token.RBRACE) // make sure we don't lose the last line comment
+ p.setLineComment("// contains filtered or unexported fields")
}
} else { // interface
if len(list) > 0 {
p.print(formfeed)
}
- p.flush(p.fset.Position(rbrace), token.RBRACE) // make sure we don't loose the last line comment
- p.setLineComment("// contains unexported methods")
+ p.flush(p.fset.Position(rbrace), token.RBRACE) // make sure we don't lose the last line comment
+ p.setLineComment("// contains filtered or unexported methods")
}
}
p.print(unindent, formfeed, rbrace, token.RBRACE)
}
-
// ----------------------------------------------------------------------------
// Expressions
}
case *ast.StarExpr:
- if e.Op.String() == "/" {
+ if e.Op == token.QUO { // `*/`
maxProblem = 5
}
return
}
-
func cutoff(e *ast.BinaryExpr, depth int) int {
has4, has5, maxProblem := walkBinary(e)
if maxProblem > 0 {
return 4
}
-
func diffPrec(expr ast.Expr, prec int) int {
x, ok := expr.(*ast.BinaryExpr)
if !ok || prec != x.Op.Precedence() {
return 0
}
-
func reduceDepth(depth int) int {
depth--
if depth < 1 {
return depth
}
-
// Format the binary expression: decide the cutoff and then format.
// Let's call depth == 1 Normal mode, and depth > 1 Compact mode.
// (Algorithm suggestion by Russ Cox.)
}
}
-
func isBinary(expr ast.Expr) bool {
_, ok := expr.(*ast.BinaryExpr)
return ok
}
-
// If the expression contains one or more selector expressions, splits it into
// two expressions at the rightmost period. Writes entire expr to suffix when
// selector isn't found. Rewrites AST nodes for calls, index expressions and
return
}
-
// Convert an expression into an expression list split at the periods of
// selector expressions.
func selectorExprList(expr ast.Expr) (list []ast.Expr) {
return
}
-
// Sets multiLine to true if the expression spans multiple lines.
func (p *printer) expr1(expr ast.Expr, prec1, depth int, multiLine *bool) {
p.print(expr.Pos())
return
}
-
func (p *printer) expr0(x ast.Expr, depth int, multiLine *bool) {
p.expr1(x, token.LowestPrec, depth, multiLine)
}
-
// Sets multiLine to true if the expression spans multiple lines.
func (p *printer) expr(x ast.Expr, multiLine *bool) {
const depth = 1
p.expr1(x, token.LowestPrec, depth, multiLine)
}
-
// ----------------------------------------------------------------------------
// Statements
}
}
-
// block prints an *ast.BlockStmt; it always spans at least two lines.
func (p *printer) block(s *ast.BlockStmt, indent int) {
p.print(s.Pos(), token.LBRACE)
p.print(s.Rbrace, token.RBRACE)
}
-
func isTypeName(x ast.Expr) bool {
switch t := x.(type) {
case *ast.Ident:
return false
}
-
func stripParens(x ast.Expr) ast.Expr {
if px, strip := x.(*ast.ParenExpr); strip {
// parentheses must not be stripped if there are any
return x
}
-
func (p *printer) controlClause(isForStmt bool, init ast.Stmt, expr ast.Expr, post ast.Stmt) {
p.print(blank)
needsBlank := false
}
}
-
// Sets multiLine to true if the statements spans multiple lines.
func (p *printer) stmt(stmt ast.Stmt, nextIsRBrace bool, multiLine *bool) {
p.print(stmt.Pos())
case *ast.SelectStmt:
p.print(token.SELECT, blank)
- p.block(s.Body, 0)
- *multiLine = true
+ body := s.Body
+ if len(body.List) == 0 && !p.commentBefore(p.fset.Position(body.Rbrace)) {
+ // print empty select statement w/o comments on one line
+ p.print(body.Lbrace, token.LBRACE, body.Rbrace, token.RBRACE)
+ } else {
+ p.block(body, 0)
+ *multiLine = true
+ }
case *ast.ForStmt:
p.print(token.FOR)
return
}
-
// ----------------------------------------------------------------------------
// Declarations
+// The keepTypeColumn function determines if the type column of a series of
+// consecutive const or var declarations must be kept, or if initialization
+// values (V) can be placed in the type column (T) instead. The i'th entry
+// in the result slice is true if the type column in spec[i] must be kept.
+//
+// For example, the declaration:
+//
+// const (
+// foobar int = 42 // comment
+// x = 7 // comment
+// foo
+// bar = 991
+// )
+//
+// leads to the type/values matrix below. A run of value columns (V) can
+// be moved into the type column if there is no type for any of the values
+// in that column (we only move entire columns so that they align properly).
+//
+// matrix formatted result
+// matrix
+// T V -> T V -> true there is a T and so the type
+// - V - V true column must be kept
+// - - - - false
+// - V V - false V is moved into T column
+//
+func keepTypeColumn(specs []ast.Spec) []bool {
+ m := make([]bool, len(specs))
+
+ populate := func(i, j int, keepType bool) {
+ if keepType {
+ for ; i < j; i++ {
+ m[i] = true
+ }
+ }
+ }
+
+ i0 := -1 // if i0 >= 0 we are in a run and i0 is the start of the run
+ var keepType bool
+ for i, s := range specs {
+ t := s.(*ast.ValueSpec)
+ if t.Values != nil {
+ if i0 < 0 {
+ // start of a run of ValueSpecs with non-nil Values
+ i0 = i
+ keepType = false
+ }
+ } else {
+ if i0 >= 0 {
+ // end of a run
+ populate(i0, i, keepType)
+ i0 = -1
+ }
+ }
+ if t.Type != nil {
+ keepType = true
+ }
+ }
+ if i0 >= 0 {
+ // end of a run
+ populate(i0, len(specs), keepType)
+ }
+
+ return m
+}
+
+func (p *printer) valueSpec(s *ast.ValueSpec, keepType, doIndent bool, multiLine *bool) {
+ p.setComment(s.Doc)
+ p.identList(s.Names, doIndent, multiLine) // always present
+ extraTabs := 3
+ if s.Type != nil || keepType {
+ p.print(vtab)
+ extraTabs--
+ }
+ if s.Type != nil {
+ p.expr(s.Type, multiLine)
+ }
+ if s.Values != nil {
+ p.print(vtab, token.ASSIGN)
+ p.exprList(token.NoPos, s.Values, 1, blankStart|commaSep, multiLine, token.NoPos)
+ extraTabs--
+ }
+ if s.Comment != nil {
+ for ; extraTabs > 0; extraTabs-- {
+ p.print(vtab)
+ }
+ p.setComment(s.Comment)
+ }
+}
+
// The parameter n is the number of specs in the group. If doIndent is set,
// multi-line identifier lists in the spec are indented when the first
// linebreak is encountered.
p.setComment(s.Doc)
if s.Name != nil {
p.expr(s.Name, multiLine)
- p.print(vtab)
+ p.print(blank)
}
p.expr(s.Path, multiLine)
p.setComment(s.Comment)
+ p.print(s.EndPos)
case *ast.ValueSpec:
+ if n != 1 {
+ p.internalError("expected n = 1; got", n)
+ }
p.setComment(s.Doc)
p.identList(s.Names, doIndent, multiLine) // always present
- if n == 1 {
- if s.Type != nil {
- p.print(blank)
- p.expr(s.Type, multiLine)
- }
- if s.Values != nil {
- p.print(blank, token.ASSIGN)
- p.exprList(token.NoPos, s.Values, 1, blankStart|commaSep, multiLine, token.NoPos)
- }
- p.setComment(s.Comment)
-
- } else {
- extraTabs := 3
- if s.Type != nil {
- p.print(vtab)
- p.expr(s.Type, multiLine)
- extraTabs--
- }
- if s.Values != nil {
- p.print(vtab, token.ASSIGN)
- p.exprList(token.NoPos, s.Values, 1, blankStart|commaSep, multiLine, token.NoPos)
- extraTabs--
- }
- if s.Comment != nil {
- for ; extraTabs > 0; extraTabs-- {
- p.print(vtab)
- }
- p.setComment(s.Comment)
- }
+ if s.Type != nil {
+ p.print(blank)
+ p.expr(s.Type, multiLine)
}
+ if s.Values != nil {
+ p.print(blank, token.ASSIGN)
+ p.exprList(token.NoPos, s.Values, 1, blankStart|commaSep, multiLine, token.NoPos)
+ }
+ p.setComment(s.Comment)
case *ast.TypeSpec:
p.setComment(s.Doc)
}
}
-
// Sets multiLine to true if the declaration spans multiple lines.
func (p *printer) genDecl(d *ast.GenDecl, multiLine *bool) {
p.setComment(d.Doc)
if d.Lparen.IsValid() {
// group of parenthesized declarations
p.print(d.Lparen, token.LPAREN)
- if len(d.Specs) > 0 {
+ if n := len(d.Specs); n > 0 {
p.print(indent, formfeed)
- var ml bool
- for i, s := range d.Specs {
- if i > 0 {
- p.linebreak(p.fset.Position(s.Pos()).Line, 1, ignore, ml)
+ if n > 1 && (d.Tok == token.CONST || d.Tok == token.VAR) {
+ // two or more grouped const/var declarations:
+ // determine if the type column must be kept
+ keepType := keepTypeColumn(d.Specs)
+ var ml bool
+ for i, s := range d.Specs {
+ if i > 0 {
+ p.linebreak(p.fset.Position(s.Pos()).Line, 1, ignore, ml)
+ }
+ ml = false
+ p.valueSpec(s.(*ast.ValueSpec), keepType[i], false, &ml)
+ }
+ } else {
+ var ml bool
+ for i, s := range d.Specs {
+ if i > 0 {
+ p.linebreak(p.fset.Position(s.Pos()).Line, 1, ignore, ml)
+ }
+ ml = false
+ p.spec(s, n, false, &ml)
}
- ml = false
- p.spec(s, len(d.Specs), false, &ml)
}
p.print(unindent, formfeed)
*multiLine = true
}
}
-
// nodeSize determines the size of n in chars after formatting.
// The result is <= maxSize if the node fits on one line with at
// most maxSize chars and the formatted output doesn't contain
size = maxSize + 1 // assume n doesn't fit
p.nodeSizes[n] = size
- // nodeSize computation must be indendent of particular
+ // nodeSize computation must be independent of particular
// style so that we always get the same decision; print
// in RawFormat
cfg := Config{Mode: RawFormat}
var buf bytes.Buffer
- if _, err := cfg.fprint(&buf, p.fset, n, p.nodeSizes); err != nil {
+ if err := cfg.fprint(&buf, p.fset, n, p.nodeSizes); err != nil {
return
}
if buf.Len() <= maxSize {
return
}
-
func (p *printer) isOneLineFunc(b *ast.BlockStmt, headerSize int) bool {
pos1 := b.Pos()
pos2 := b.Rbrace
return headerSize+bodySize <= maxSize
}
-
// Sets multiLine to true if the function body spans multiple lines.
func (p *printer) funcBody(b *ast.BlockStmt, headerSize int, isLit bool, multiLine *bool) {
if b == nil {
return
}
- p.nesting++
- defer func() {
- p.nesting--
- }()
-
if p.isOneLineFunc(b, headerSize) {
sep := vtab
if isLit {
*multiLine = true
}
-
// distance returns the column difference between from and to if both
// are on the same line; if they are on different lines (or unknown)
// the result is infinity.
return infinity
}
-
// Sets multiLine to true if the declaration spans multiple lines.
func (p *printer) funcDecl(d *ast.FuncDecl, multiLine *bool) {
p.setComment(d.Doc)
p.funcBody(d.Body, p.distance(d.Pos(), p.pos), false, multiLine)
}
-
// Sets multiLine to true if the declaration spans multiple lines.
func (p *printer) decl(decl ast.Decl, multiLine *bool) {
switch d := decl.(type) {
}
}
-
// ----------------------------------------------------------------------------
// Files
return
}
-
func (p *printer) file(src *ast.File) {
p.setComment(src.Doc)
p.print(src.Pos(), token.PACKAGE, blank)
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