go/printer/gofmt: remove special case for multi-line raw strings

As a special case, multi-line raw strings (i.e., strings in `` quotes)
were not indented if they were the only token on a line. This heuristic
was meant to improve formatting for multi-line raw strings where sub-
sequent lines are not indented at the level of the surrounding code.
Multiple people have complained about this. Removing the heuristic
again because it makes the formatting more regular, easier to under-
stand, and simplifies the implementation.

- manual changes to ebnf/ebnf_test.go for readability
- gofmt -w src misc

Fixes #1643.

R=r, rsc
CC=golang-dev
https://golang.org/cl/4307045

src/pkg/ebnf/ebnf_test.go

@@ -15,18 +15,14 @@ var fset = token.NewFileSet()
 
 
 var grammars = []string{
-`Program = .
+	`Program = .`,
-`,
 
 	`Program = foo .
-foo = "foo" .
+	 foo = "foo" .`,
-`,
 
-`Program = "a" | "b" "c" .
+	`Program = "a" | "b" "c" .`,
-`,
 
-`Program = "a" ... "z" .
+	`Program = "a" ... "z" .`,
-`,
 
 	`Program = Song .
 	 Song = { Note } .
@@ -38,8 +34,7 @@ foo = "foo" .
 	 So = "g" .
 	 La = "a" .
 	 Ti = ti .
- ti = "b" .
+	 ti = "b" .`,
-`,
 }
 
 

src/pkg/go/printer/printer.go

@@ -14,7 +14,6 @@ import (
 	"os"
 	"path/filepath"
 	"runtime"
-	"strings"
 	"tabwriter"
 )
 
@@ -35,13 +34,6 @@ const (
 )
 
 
-const (
-	esc2    = '\xfe'                        // an escape byte that cannot occur in regular UTF-8
-	_       = 1 / (esc2 - tabwriter.Escape) // cause compiler error if esc2 == tabwriter.Escape
-	esc2str = "\xfe"
-)
-
-
 var (
 	esc       = []byte{tabwriter.Escape}
 	htab      = []byte{'\t'}
@@ -775,21 +767,7 @@ func (p *printer) print(args ...interface{}) {
 			data = x.Name
 			tok = token.IDENT
 		case *ast.BasicLit:
-			// If we have a raw string that spans multiple lines and
-			// the opening quote (`) is on a line preceded only by
-			// indentation, we don't want to write that indentation
-			// because the following lines of the raw string are not
-			// indented. It's easiest to correct the output at the end
-			// via the trimmer (because of the complex handling of
-			// white space).
-			// Mark multi-line raw strings by replacing the opening
-			// quote with esc2 and have the trimmer take care of fixing
-			// it up.
-			if x.Value[0] == '`' && strings.Index(x.Value, "\n") > 0 {
-				data = p.escape(esc2str + x.Value[1:])
-			} else {
 			data = p.escape(x.Value)
-			}
 			tok = x.Kind
 		case token.Token:
 			s := x.String()
@@ -874,7 +852,6 @@ type trimmer struct {
 	output io.Writer
 	state  int
 	space  bytes.Buffer
-	hasText bool
 }
 
 
@@ -882,15 +859,11 @@ type trimmer struct {
 // It can be in one of the following states:
 const (
 	inSpace  = iota // inside space
-	atEscape        // inside space and the last char was an opening tabwriter.Escape
 	inEscape        // inside text bracketed by tabwriter.Escapes
 	inText          // inside text
 )
 
 
-var backquote = []byte{'`'}
-
-
 // Design note: It is tempting to eliminate extra blanks occurring in
 //              whitespace in this function as it could simplify some
 //              of the blanks logic in the node printing functions.
@@ -899,9 +872,8 @@ var backquote = []byte{'`'}
 
 func (p *trimmer) Write(data []byte) (n int, err os.Error) {
 	// invariants:
-	// p.state == inSpace, atEscape:
+	// p.state == inSpace:
 	//	p.space is unwritten
-	//	p.hasText indicates if there is any text on this line
 	// p.state == inEscape, inText:
 	//	data[m:n] is unwritten
 	m := 0
@@ -918,32 +890,20 @@ func (p *trimmer) Write(data []byte) (n int, err os.Error) {
 			case '\n', '\f':
 				p.space.Reset()                        // discard trailing space
 				_, err = p.output.Write(newlines[0:1]) // write newline
-				p.hasText = false
 			case tabwriter.Escape:
-				p.state = atEscape
+				_, err = p.output.Write(p.space.Bytes())
+				p.state = inEscape
+				m = n + 1 // +1: skip tabwriter.Escape
 			default:
 				_, err = p.output.Write(p.space.Bytes())
 				p.state = inText
 				m = n
 			}
-		case atEscape:
-			// discard indentation if we have a multi-line raw string
-			// (see printer.print for details)
-			if b != esc2 || p.hasText {
-				_, err = p.output.Write(p.space.Bytes())
-			}
-			p.state = inEscape
-			m = n
-			if b == esc2 {
-				_, err = p.output.Write(backquote) // convert back
-				m++
-			}
 		case inEscape:
 			if b == tabwriter.Escape {
 				_, err = p.output.Write(data[m:n])
 				p.state = inSpace
 				p.space.Reset()
-				p.hasText = true
 			}
 		case inText:
 			switch b {
@@ -952,19 +912,18 @@ func (p *trimmer) Write(data []byte) (n int, err os.Error) {
 				p.state = inSpace
 				p.space.Reset()
 				p.space.WriteByte(b) // WriteByte returns no errors
-				p.hasText = true
 			case '\n', '\f':
 				_, err = p.output.Write(data[m:n])
 				p.state = inSpace
 				p.space.Reset()
 				_, err = p.output.Write(newlines[0:1]) // write newline
-				p.hasText = false
 			case tabwriter.Escape:
 				_, err = p.output.Write(data[m:n])
-				p.state = atEscape
+				p.state = inEscape
-				p.space.Reset()
+				m = n + 1 // +1: skip tabwriter.Escape
-				p.hasText = true
 			}
+		default:
+			panic("unreachable")
 		}
 		if err != nil {
 			return
@@ -977,7 +936,6 @@ func (p *trimmer) Write(data []byte) (n int, err os.Error) {
 		_, err = p.output.Write(data[m:n])
 		p.state = inSpace
 		p.space.Reset()
-		p.hasText = true
 	}
 
 	return

src/pkg/go/printer/testdata/expressions.golden

@@ -253,7 +253,7 @@ bar`
 	var _ = ``
 	var _ = `foo`
 	var _ =
-	// the next line should not be indented
+	// the next line should remain indented
 	`foo
 bar`
 
@@ -262,7 +262,7 @@ bar`
 	var _ =	// comment
 	`foo`
 	var _ =	// comment
-	// the next line should not be indented
+	// the next line should remain indented
 	`foo
 bar`
 
@@ -276,7 +276,7 @@ bar`
 	var _ =	/* comment */
 	`foo`
 	var _ =	/* comment */
-	// the next line should not be indented
+	// the next line should remain indented
 	`foo
 bar`
 
@@ -296,7 +296,7 @@ bar`
 
 	var state = S{
 		"foo",
-		// the next line should not be indented
+		// the next line should remain indented
 		`...........
 ...........
 ....●●●....

src/pkg/go/printer/testdata/expressions.input

@@ -256,7 +256,7 @@ var _ =
 var _ =
 	`foo`
 var _ =
-	// the next line should not be indented
+	// the next line should remain indented
 	`foo
 bar`
 
@@ -266,7 +266,7 @@ bar`
 	var _ = // comment
 		`foo`
 	var _ = // comment
-		// the next line should not be indented
+		// the next line should remain indented
 		`foo
 bar`
 
@@ -282,7 +282,7 @@ bar`
 	var _ = /* comment */
 		`foo`
 	var _ = /* comment */
-		// the next line should not be indented
+		// the next line should remain indented
 		`foo
 bar`
 
@@ -304,7 +304,7 @@ var board = []int(
 
 	var state = S{
 		"foo",
-		// the next line should not be indented
+		// the next line should remain indented
 		`...........
 ...........
 ....●●●....

src/pkg/go/printer/testdata/expressions.raw

@@ -239,7 +239,8 @@ func _() {
 	_ = `foo
 		bar`
 	_ = `three spaces before the end of the line starting here:   
-they must not be removed`}
+they must not be removed`
+}
 
 
 func _() {
@@ -252,7 +253,7 @@ bar`
 	var _ = ``
 	var _ = `foo`
 	var _ =
-	// the next line should not be indented
+	// the next line should remain indented
 	`foo
 bar`
 
@@ -261,7 +262,7 @@ bar`
 	var _ =	// comment
 	`foo`
 	var _ =	// comment
-	// the next line should not be indented
+	// the next line should remain indented
 	`foo
 bar`
 
@@ -275,7 +276,7 @@ bar`
 	var _ =	/* comment */
 	`foo`
 	var _ =	/* comment */
-	// the next line should not be indented
+	// the next line should remain indented
 	`foo
 bar`
 
@@ -295,7 +296,7 @@ bar`
 
 	var state = S{
 		"foo",
-		// the next line should not be indented
+		// the next line should remain indented
 		`...........
 ...........
 ....●●●....