go/scanner: support for complex (imaginary) constants

R=rsc
CC=golang-dev
https://golang.org/cl/223044

src/pkg/go/parser/parser.go

@@ -959,7 +959,7 @@ func (p *parser) parseOperand() ast.Expr {
 	case token.IDENT:
 		return p.findIdent()
 
-	case token.INT, token.FLOAT, token.CHAR, token.STRING:
+	case token.INT, token.FLOAT, token.IMAG, token.CHAR, token.STRING:
 		x := &ast.BasicLit{p.pos, p.tok, p.lit}
 		p.next()
 		return x

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

@@ -68,6 +68,48 @@ import _ "io"
 var _ int
 
 
+// printing of constant literals
+const (
+	_	= "foobar"
+	_	= "a۰۱۸"
+	_	= "foo६४"
+	_	= "bar９８７６"
+	_	= 0
+	_	= 1
+	_	= 123456789012345678890
+	_	= 01234567
+	_	= 0xcafebabe
+	_	= 0.
+	_	= .0
+	_	= 3.14159265
+	_	= 1e0
+	_	= 1e+100
+	_	= 1e-100
+	_	= 2.71828e-1000
+	_	= 0i
+	_	= 1i
+	_	= 012345678901234567889i
+	_	= 123456789012345678890i
+	_	= 0.i
+	_	= .0i
+	_	= 3.14159265i
+	_	= 1e0i
+	_	= 1e+100i
+	_	= 1e-100i
+	_	= 2.71828e-1000i
+	_	= 'a'
+	_	= '\000'
+	_	= '\xFF'
+	_	= '\uff16'
+	_	= '\U0000ff16'
+	_	= `foobar`
+	_	= `foo
+---
+---
+bar`
+)
+
+
 func _() {
 	// the following decls need a semicolon at the end
 	type _ int

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

@@ -67,6 +67,48 @@ import _ "io"
 var _ int
 
 
+// printing of constant literals
+const (
+	_ = "foobar"
+	_ = "a۰۱۸"
+	_ = "foo६४"
+	_ = "bar９８７６"
+	_ = 0
+	_ = 1
+	_ = 123456789012345678890
+	_ = 01234567
+	_ = 0xcafebabe
+	_ = 0.
+	_ = .0
+	_ = 3.14159265
+	_ = 1e0
+	_ = 1e+100
+	_ = 1e-100
+	_ = 2.71828e-1000
+	_ = 0i
+	_ = 1i
+	_ = 012345678901234567889i
+	_ = 123456789012345678890i
+	_ = 0.i
+	_ = .0i
+	_ = 3.14159265i
+	_ = 1e0i
+	_ = 1e+100i
+	_ = 1e-100i
+	_ = 2.71828e-1000i
+	_ = 'a'
+	_ = '\000'
+	_ = '\xFF'
+	_ = '\uff16'
+	_ = '\U0000ff16'
+	_ = `foobar`
+	_ = `foo
+---
+---
+bar`
+)
+
+
 func _() {
 	// the following decls need a semicolon at the end
 	type _ int

src/pkg/go/scanner/scanner.go

@@ -302,7 +302,7 @@ func (S *Scanner) scanNumber(pos token.Position, seenDecimalPoint bool) token.To
 				seenDecimalDigit = true
 				S.scanMantissa(10)
 			}
-			if S.ch == '.' || S.ch == 'e' || S.ch == 'E' {
+			if S.ch == '.' || S.ch == 'e' || S.ch == 'E' || S.ch == 'i' {
 				goto fraction
 			}
 			// octal int
@@ -333,6 +333,11 @@ exponent:
 		S.scanMantissa(10)
 	}
 
+	if S.ch == 'i' {
+		tok = token.IMAG
+		S.next()
+	}
+
 exit:
 	return tok
 }

src/pkg/go/scanner/scanner_test.go

@@ -51,6 +51,8 @@ var tokens = [...]elt{
 	elt{token.IDENT, "foo६४", literal},
 	elt{token.IDENT, "bar９８７６", literal},
 	elt{token.INT, "0", literal},
+	elt{token.INT, "1", literal},
+	elt{token.INT, "123456789012345678890", literal},
 	elt{token.INT, "01234567", literal},
 	elt{token.INT, "0xcafebabe", literal},
 	elt{token.FLOAT, "0.", literal},
@@ -60,6 +62,17 @@ var tokens = [...]elt{
 	elt{token.FLOAT, "1e+100", literal},
 	elt{token.FLOAT, "1e-100", literal},
 	elt{token.FLOAT, "2.71828e-1000", literal},
+	elt{token.IMAG, "0i", literal},
+	elt{token.IMAG, "1i", literal},
+	elt{token.IMAG, "012345678901234567889i", literal},
+	elt{token.IMAG, "123456789012345678890i", literal},
+	elt{token.IMAG, "0.i", literal},
+	elt{token.IMAG, ".0i", literal},
+	elt{token.IMAG, "3.14159265i", literal},
+	elt{token.IMAG, "1e0i", literal},
+	elt{token.IMAG, "1e+100i", literal},
+	elt{token.IMAG, "1e-100i", literal},
+	elt{token.IMAG, "2.71828e-1000i", literal},
 	elt{token.CHAR, "'a'", literal},
 	elt{token.CHAR, "'\\000'", literal},
 	elt{token.CHAR, "'\\xFF'", literal},

src/pkg/go/token/token.go

@@ -30,6 +30,7 @@ const (
 	IDENT  // main
 	INT    // 12345
 	FLOAT  // 123.45
+	IMAG   // 123.45i
 	CHAR   // 'a'
 	STRING // "abc"
 	literal_end
@@ -140,6 +141,7 @@ var tokens = map[Token]string{
 	IDENT: "IDENT",
 	INT: "INT",
 	FLOAT: "FLOAT",
+	IMAG: "IMAG",
 	CHAR: "CHAR",
 	STRING: "STRING",