+// 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)
+ }
+}
+