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Commit 832ce7c1 authored by Robert Griesemer's avatar Robert Griesemer
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format composite literal types that are "short" struct type literals 

on one line for a more compact representation of some composite Literals

R=rsc
http://go/go-review/1025008
parent a05a5465
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Inline Side-by-side
Showing with 123 additions and 21 deletions
src/pkg/go/printer/nodes.go
View file @ 832ce7c1
......@@ -25,7 +25,6 @@ const (
// Other formatting issues:
// - replacement of expression spacing algorithm with rsc's algorithm
// - support for one-line composite types (e.g. structs) as composite literals types
// - 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
// not idempotent
......@@ -262,16 +261,70 @@ func (p *printer) signature(params, result []*ast.Field, multiLine *bool) (optSe
}
func (p *printer) fieldList(lbrace token.Position, list []*ast.Field, rbrace token.Position, isIncomplete, isStruct bool) {
if len(list) == 0 && !isIncomplete && !p.commentBefore(rbrace) {
// no blank between keyword and {} in this case
p.print(lbrace, token.LBRACE, rbrace, token.RBRACE);
return;
func identListSize(list []*ast.Ident, maxSize int) (size int) {
for i, x := range list {
if i > 0 {
size += 2; // ", "
}
size += len(x.Value);
if size >= maxSize {
break;
}
}
return;
}
func (p *printer) isOneLineFieldList(list []*ast.Field) bool {
if len(list) != 1 {
return false; // allow only one field
}
f := list[0];
if f.Tag != nil || f.Comment != nil {
return false; // don't allow tags or comments
}
// only name(s) and type
const maxSize = 30; // adjust as appropriate, this is an approximate value
namesSize := identListSize(f.Names, maxSize);
if namesSize > 0 {
namesSize = 1; // blank between names and types
}
typeSize := p.nodeSize(f.Type, maxSize);
return namesSize + typeSize <= maxSize;
}
func (p *printer) fieldList(lbrace token.Position, list []*ast.Field, rbrace token.Position, isIncomplete bool, ctxt Context) {
if !isIncomplete && !p.commentBefore(rbrace) {
// possibly a one-line struct/interface
if len(list) == 0 {
// no blank between keyword and {} in this case
p.print(lbrace, token.LBRACE, rbrace, token.RBRACE);
return;
} else if ctxt&(compositeLit | structType) == compositeLit | structType &&
p.isOneLineFieldList(list) { // for now ignore interfaces
// small enough - print on one line
// (don't use identList and ignore source line breaks)
p.print(lbrace, token.LBRACE, blank);
f := list[0];
for i, x := range f.Names {
if i > 0 {
p.print(token.COMMA, blank);
}
p.expr(x, ignoreMultiLine);
}
if len(f.Names) > 0 {
p.print(blank);
}
p.expr(f.Type, ignoreMultiLine);
p.print(blank, rbrace, token.RBRACE);
return;
}
}
// at least one entry or incomplete
p.print(blank, lbrace, token.LBRACE, indent, formfeed);
if isStruct {
if ctxt & structType != 0 {
sep := vtab;
if len(list) == 1 {
......@@ -286,11 +339,13 @@ func (p *printer) fieldList(lbrace token.Position, list []*ast.Field, rbrace tok
extraTabs := 0;
p.leadComment(f.Doc);
if len(f.Names) > 0 {
// named fields
p.identList(f.Names, &ml);
p.print(sep);
p.expr(f.Type, &ml);
extraTabs = 1;
} else {
// anonymous field
p.expr(f.Type, &ml);
extraTabs = 2;
}
......@@ -354,6 +409,15 @@ func (p *printer) fieldList(lbrace token.Position, list []*ast.Field, rbrace tok
// ----------------------------------------------------------------------------
// Expressions
// Context describes the syntactic environment in which an expression node is printed.
type Context uint
const (
compositeLit = 1<<iota;
structType;
)
func needsBlanks(expr ast.Expr) bool {
switch x := expr.(type) {
case *ast.Ident:
......@@ -420,7 +484,7 @@ func (p *printer) binaryExpr(x *ast.BinaryExpr, prec1 int, multiLine *bool) {
// Print collected operations left-to-right, with blanks if necessary.
ws := indent;
p.expr1(x.X, prec, multiLine);
p.expr1(x.X, prec, 0, multiLine);
for list.Len() > 0 {
x = list.Pop().(*ast.BinaryExpr);
prev := line;
......@@ -443,7 +507,7 @@ func (p *printer) binaryExpr(x *ast.BinaryExpr, prec1 int, multiLine *bool) {
}
p.print(x.OpPos, x.Op);
}
p.expr1(x.Y, prec, multiLine);
p.expr1(x.Y, prec, 0, multiLine);
}
if ws == ignore {
p.print(unindent);
......@@ -453,7 +517,7 @@ func (p *printer) binaryExpr(x *ast.BinaryExpr, prec1 int, multiLine *bool) {
// Returns true if a separating semicolon is optional.
// Sets multiLine to true if the expression spans multiple lines.
func (p *printer) expr1(expr ast.Expr, prec1 int, multiLine *bool) (optSemi bool) {
func (p *printer) expr1(expr ast.Expr, prec1 int, ctxt Context, multiLine *bool) (optSemi bool) {
p.print(expr.Pos());
switch x := expr.(type) {
......@@ -488,7 +552,7 @@ func (p *printer) expr1(expr ast.Expr, prec1 int, multiLine *bool) (optSemi bool
if x.Op == token.RANGE {
p.print(blank);
}
p.expr1(x.X, prec, multiLine);
p.expr1(x.X, prec, 0, multiLine);
}
case *ast.BasicLit:
......@@ -507,12 +571,12 @@ func (p *printer) expr1(expr ast.Expr, prec1 int, multiLine *bool) (optSemi bool
p.print(x.Rparen, token.RPAREN);
case *ast.SelectorExpr:
p.expr1(x.X, token.HighestPrec, multiLine);
p.expr1(x.X, token.HighestPrec, 0, multiLine);
p.print(token.PERIOD);
p.expr1(x.Sel, token.HighestPrec, multiLine);
p.expr1(x.Sel, token.HighestPrec, 0, multiLine);
case *ast.TypeAssertExpr:
p.expr1(x.X, token.HighestPrec, multiLine);
p.expr1(x.X, token.HighestPrec, 0, multiLine);
p.print(token.PERIOD, token.LPAREN);
if x.Type != nil {
p.expr(x.Type, multiLine);
......@@ -522,9 +586,9 @@ func (p *printer) expr1(expr ast.Expr, prec1 int, multiLine *bool) (optSemi bool
p.print(token.RPAREN);
case *ast.IndexExpr:
p.expr1(x.X, token.HighestPrec, multiLine);
p.expr1(x.X, token.HighestPrec, 0, multiLine);
p.print(token.LBRACK);
p.expr1(x.Index, token.LowestPrec, multiLine);
p.expr1(x.Index, token.LowestPrec, 0, multiLine);
if x.End != nil {
if needsBlanks(x.Index) || needsBlanks(x.End) {
// blanks around ":"
......@@ -538,13 +602,13 @@ func (p *printer) expr1(expr ast.Expr, prec1 int, multiLine *bool) (optSemi bool
p.print(token.RBRACK);
case *ast.CallExpr:
p.expr1(x.Fun, token.HighestPrec, multiLine);
p.expr1(x.Fun, token.HighestPrec, 0, multiLine);
p.print(x.Lparen, token.LPAREN);
p.exprList(x.Lparen, x.Args, commaSep, multiLine);
p.print(x.Rparen, token.RPAREN);
case *ast.CompositeLit:
p.expr1(x.Type, token.HighestPrec, multiLine);
p.expr1(x.Type, token.HighestPrec, compositeLit, multiLine);
if compositeLitBlank && x.Lbrace.Line < x.Rbrace.Line {
// add a blank before the opening { for multi-line composites
// TODO(gri): for now this decision is made by looking at the
......@@ -569,7 +633,7 @@ func (p *printer) expr1(expr ast.Expr, prec1 int, multiLine *bool) (optSemi bool
case *ast.StructType:
p.print(token.STRUCT);
p.fieldList(x.Lbrace, x.Fields, x.Rbrace, x.Incomplete, true);
p.fieldList(x.Lbrace, x.Fields, x.Rbrace, x.Incomplete, ctxt | structType);
optSemi = true;
case *ast.FuncType:
......@@ -578,7 +642,7 @@ func (p *printer) expr1(expr ast.Expr, prec1 int, multiLine *bool) (optSemi bool
case *ast.InterfaceType:
p.print(token.INTERFACE);
p.fieldList(x.Lbrace, x.Methods, x.Rbrace, x.Incomplete, false);
p.fieldList(x.Lbrace, x.Methods, x.Rbrace, x.Incomplete, ctxt);
optSemi = true;
case *ast.MapType:
......@@ -610,7 +674,7 @@ func (p *printer) expr1(expr ast.Expr, prec1 int, multiLine *bool) (optSemi bool
// Returns true if a separating semicolon is optional.
// Sets multiLine to true if the expression spans multiple lines.
func (p *printer) expr(x ast.Expr, multiLine *bool) (optSemi bool) {
return p.expr1(x, token.LowestPrec, multiLine);
return p.expr1(x, token.LowestPrec, 0, multiLine);
}
......
src/pkg/go/printer/testdata/expressions.golden
View file @ 832ce7c1
......@@ -104,6 +104,20 @@ func _() {
}
// one-line structs/interfaces in composite literals (up to a threshold)
func _() {
_ = struct{}{};
_ = struct{ x int }{0};
_ = struct{ x, y, z int }{0, 1, 2};
_ = struct{ int }{0};
_ = struct {
s struct {
int;
};
}{struct{ int }{0}}; // compositeLit context not propagated => multiLine result
}
func _() {
// do not modify literals
_ = "tab1 tab2 tab3 end"; // string contains 3 tabs
......
src/pkg/go/printer/testdata/expressions.input
View file @ 832ce7c1
......@@ -104,6 +104,16 @@ func _() {
}
// one-line structs/interfaces in composite literals (up to a threshold)
func _() {
_ = struct{}{};
_ = struct{ x int }{0};
_ = struct{ x, y, z int }{0, 1, 2};
_ = struct{ int }{0};
_ = struct{ s struct { int } }{struct{ int}{0}}; // compositeLit context not propagated => multiLine result
}
func _() {
// do not modify literals
_ = "tab1 tab2 tab3 end"; // string contains 3 tabs
......
src/pkg/go/printer/testdata/expressions.raw
View file @ 832ce7c1
......@@ -104,6 +104,20 @@ func _() {
}
// one-line structs/interfaces in composite literals (up to a threshold)
func _() {
_ = struct{}{};
_ = struct{ x int }{0};
_ = struct{ x, y, z int }{0, 1, 2};
_ = struct{ int }{0};
_ = struct {
s struct {
int;
};
}{struct{ int }{0}}; // compositeLit context not propagated => multiLine result
}
func _() {
// do not modify literals
_ = "tab1 tab2 tab3 end"; // string contains 3 tabs
......
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