Get borrowed_scanner_test.go passing [ci-skip]

1 files changed, 34 insertions, 21 deletions

diff --git a/misc.go b/misc.go
index 4d8b136..ad69d91 100644
--- a/misc.go
+++ b/misc.go
@@ -107,6 +107,10 @@ func EscapeDefault(c rune, wasEscaped BackslashEscapeMode) BackslashEscapeMode {
 	}
 }
 
+func EscapePreserve(_ rune, wasEscaped BackslashEscapeMode) BackslashEscapeMode {
+	return wasEscaped
+}
+
 func writeStringUnicodeEscape(w io.Writer, c rune) (int, error) {
 	buf := [6]byte{
 		'\\',
@@ -118,8 +122,25 @@ func writeStringUnicodeEscape(w io.Writer, c rune) (int, error) {
 	}
 	return w.Write(buf[:])
 }
-func writeStringShortEscape(w io.Writer, c byte) (int, error) {
-	buf := [2]byte{'\\', c}
+func writeStringShortEscape(w io.Writer, c rune) (int, error) {
+	var b byte
+	switch c {
+	case '"', '\\', '/':
+		b = byte(c)
+	case '\b':
+		b = 'b'
+	case '\f':
+		b = 'f'
+	case '\n':
+		b = 'n'
+	case '\r':
+		b = 'r'
+	case '\t':
+		b = 't'
+	default:
+		panic("should not happen")
+	}
+	buf := [2]byte{'\\', b}
 	return w.Write(buf[:])
 }
 func writeStringChar(w io.Writer, c rune, wasEscaped BackslashEscapeMode, escaper func(rune, BackslashEscapeMode) BackslashEscapeMode) (int, error) {
@@ -129,38 +150,30 @@ func writeStringChar(w io.Writer, c rune, wasEscaped BackslashEscapeMode, escape
 	switch escaper(c, wasEscaped) {
 	case BackslashEscapeNone:
 		switch {
-		case c < 0x0020:
+		case c < 0x0020: // override, gotta escape these
 			switch c {
-			case '\b':
-				return writeStringShortEscape(w, 'b')
-			case '\f':
-				return writeStringShortEscape(w, 'f')
-			case '\n':
-				return writeStringShortEscape(w, 'n')
-			case '\r':
-				return writeStringShortEscape(w, 'r')
-			case '\t':
-				return writeStringShortEscape(w, 't')
+			case '\b', '\f', '\n', '\r', '\t': // short-escape if possible
+				return writeStringShortEscape(w, c)
 			default:
 				return writeStringUnicodeEscape(w, c)
 			}
-		case c == '"' || c == '\\':
-			return writeStringShortEscape(w, byte(c))
-		default:
+		case c == '"' || c == '\\': // override, gotta escape these
+			return writeStringShortEscape(w, c)
+		default: // obey
 			return writeRune(w, c)
 		}
 	case BackslashEscapeShort:
 		switch c {
-		case '"', '\\', '/', '\b', '\f', '\n', '\r', '\t':
-			return writeStringShortEscape(w, byte(c))
-		default:
+		case '"', '\\', '/', '\b', '\f', '\n', '\r', '\t': // obey
+			return writeStringShortEscape(w, c)
+		default: // override, can't short-escape these
 			return writeRune(w, c)
 		}
 	case BackslashEscapeUnicode:
 		switch {
-		case c > 0xFFFF:
+		case c > 0xFFFF: // override, can't escape these (TODO: unless we use UTF-16 surrogates?)
 			return writeRune(w, c)
-		default:
+		default: // obey
 			return writeStringUnicodeEscape(w, c)
 		}
 	default: