parse: Add QuoteAs, move [qQ]uote* to quote.go.

parse/parse.go

@@ -1038,84 +1038,7 @@ func isSpaceOrNewline(r rune) bool {
 	return isSpace(r) || r == '\n'
 }
 
-// Helpers.
-
 func addChild(p Node, ch Node) {
 	p.n().children = append(p.n().children, ch)
 	ch.n().parent = p
 }
-
-// Quote returns a representation of s in elvish syntax. Bareword is tried
-// first, then single quoted string and finally double quoted string.
-func Quote(s string) string {
-	if s == "" {
-		return `""`
-	}
-	bare := s[0] != '~'
-	for _, r := range s {
-		if !unicode.IsPrint(r) && r != '\n' {
-			return quoteDouble(s)
-		}
-		if !allowedInBareword(r) {
-			bare = false
-		}
-	}
-	if bare {
-		return s
-	}
-	return quoteSingle(s)
-}
-
-func quoteSingle(s string) string {
-	var buf bytes.Buffer
-	buf.WriteByte('\'')
-	for _, r := range s {
-		buf.WriteRune(r)
-		if r == '\'' {
-			buf.WriteByte('\'')
-		}
-	}
-	buf.WriteByte('\'')
-	return buf.String()
-}
-
-func rtohex(r rune, w int) []byte {
-	bytes := make([]byte, w)
-	for i := w - 1; i >= 0; i-- {
-		d := byte(r % 16)
-		r /= 16
-		if d <= 9 {
-			bytes[i] = '0' + d
-		} else {
-			bytes[i] = 'a' + d - 10
-		}
-	}
-	return bytes
-}
-
-func quoteDouble(s string) string {
-	var buf bytes.Buffer
-	buf.WriteByte('"')
-	for _, r := range s {
-		if r == '\\' || r == '"' {
-			buf.WriteByte('\\')
-			buf.WriteRune(r)
-		} else if !unicode.IsPrint(r) {
-			buf.WriteByte('\\')
-			if r <= 0xff {
-				buf.WriteByte('x')
-				buf.Write(rtohex(r, 2))
-			} else if r <= 0xffff {
-				buf.WriteByte('u')
-				buf.Write(rtohex(r, 4))
-			} else {
-				buf.WriteByte('U')
-				buf.Write(rtohex(r, 8))
-			}
-		} else {
-			buf.WriteRune(r)
-		}
-	}
-	buf.WriteByte('"')
-	return buf.String()
-}

parse/parse_test.go

@@ -350,28 +350,3 @@ func TestParseError(t *testing.T) {
 		}
 	}
 }
-
-var quoteTests = []struct {
-	text, quoted string
-}{
-	// Empty string is quoted with double quote.
-	{"", `""`},
-	// Bareword when possible.
-	{"x-y,z@h/d", "x-y,z@h/d"},
-	// Single quote when there is special char but no unprintable.
-	{"x$y[]\nef'", "'x$y[]\nef'''"},
-	// Tilde needs quoting only when appearing at the beginning
-	{"~x", "'~x'"},
-	{"x~", "x~"},
-	// Double quote when there is unprintable char.
-	{"\x1b\"\\", `"\x1b\"\\"`},
-}
-
-func TestQuote(t *testing.T) {
-	for _, tc := range quoteTests {
-		got := Quote(tc.text)
-		if got != tc.quoted {
-			t.Errorf("Quote(%q) => %s, want %s", tc.text, got, tc.quoted)
-		}
-	}
-}

parse/quote.go

@@ -0,0 +1,98 @@
+package parse
+
+import (
+	"bytes"
+	"unicode"
+)
+
+// Quote returns a representation of s in elvish syntax. Bareword is tried
+// first, then single quoted string and finally double quoted string.
+func Quote(s string) string {
+	s, _ = QuoteAs(s, Bareword)
+	return s
+}
+
+// QuoteAs returns a representation of s in elvish syntax, using the syntax
+// specified by q, which must be one of Bareword, SingleQuoted, or
+// DoubleQuoted. It returns the quoted string and the actual quoting.
+func QuoteAs(s string, q PrimaryType) (string, PrimaryType) {
+	if q == DoubleQuoted {
+		// Everything can be quoted using double quotes, return directly.
+		return quoteDouble(s), DoubleQuoted
+	}
+	if s == "" {
+		return "''", SingleQuoted
+	}
+
+	// Keep track of whether it is a valid bareword.
+	bare := s[0] != '~'
+	for _, r := range s {
+		if !unicode.IsPrint(r) && r != '\n' {
+			// Contains unprintable character that is not a newline. Force
+			// double quote.
+			return quoteDouble(s), DoubleQuoted
+		}
+		if !allowedInBareword(r) {
+			bare = false
+		}
+	}
+
+	if q == Bareword && bare {
+		return s, Bareword
+	}
+	return quoteSingle(s), SingleQuoted
+}
+
+func quoteSingle(s string) string {
+	var buf bytes.Buffer
+	buf.WriteByte('\'')
+	for _, r := range s {
+		buf.WriteRune(r)
+		if r == '\'' {
+			buf.WriteByte('\'')
+		}
+	}
+	buf.WriteByte('\'')
+	return buf.String()
+}
+
+func rtohex(r rune, w int) []byte {
+	bytes := make([]byte, w)
+	for i := w - 1; i >= 0; i-- {
+		d := byte(r % 16)
+		r /= 16
+		if d <= 9 {
+			bytes[i] = '0' + d
+		} else {
+			bytes[i] = 'a' + d - 10
+		}
+	}
+	return bytes
+}
+
+func quoteDouble(s string) string {
+	var buf bytes.Buffer
+	buf.WriteByte('"')
+	for _, r := range s {
+		if r == '\\' || r == '"' {
+			buf.WriteByte('\\')
+			buf.WriteRune(r)
+		} else if !unicode.IsPrint(r) {
+			buf.WriteByte('\\')
+			if r <= 0xff {
+				buf.WriteByte('x')
+				buf.Write(rtohex(r, 2))
+			} else if r <= 0xffff {
+				buf.WriteByte('u')
+				buf.Write(rtohex(r, 4))
+			} else {
+				buf.WriteByte('U')
+				buf.Write(rtohex(r, 8))
+			}
+		} else {
+			buf.WriteRune(r)
+		}
+	}
+	buf.WriteByte('"')
+	return buf.String()
+}

parse/quote_test.go

@@ -0,0 +1,28 @@
+package parse
+
+import "testing"
+
+var quoteTests = []struct {
+	text, quoted string
+}{
+	// Empty string is quoted with single quote.
+	{"", `''`},
+	// Bareword when possible.
+	{"x-y,z@h/d", "x-y,z@h/d"},
+	// Single quote when there is special char but no unprintable.
+	{"x$y[]\nef'", "'x$y[]\nef'''"},
+	// Tilde needs quoting only when appearing at the beginning
+	{"~x", "'~x'"},
+	{"x~", "x~"},
+	// Double quote when there is unprintable char.
+	{"\x1b\"\\", `"\x1b\"\\"`},
+}
+
+func TestQuote(t *testing.T) {
+	for _, tc := range quoteTests {
+		got := Quote(tc.text)
+		if got != tc.quoted {
+			t.Errorf("Quote(%q) => %s, want %s", tc.text, got, tc.quoted)
+		}
+	}
+}