Shellwords: Simpler error and implementation

bot/extras/shellwords/shellwords.go

@@ -1,48 +1,35 @@
 package shellwords
 
 import (
-	"fmt"
 	"strings"
 )
 
-// WordOffset is the offset from the position cursor to print on the error.
-const WordOffset = 7
-
 var escaper = strings.NewReplacer(
-	"`", "\\`",
-	"@", "\\@",
+	"__", "\\_\\_",
 	"\\", "\\\\",
 )
 
-type ErrParse struct {
+// ErrMissingClose is returned when the parsed line is missing a closing quote.
+type ErrMissingClose struct {
 	Position int
 	Words    string // joined
 }
 
-func (e ErrParse) Error() string {
-	// Magic number 5.
-	var a = max(0, e.Position-WordOffset)
-	var b = min(len(e.Words), e.Position+WordOffset)
-	var word = e.Words[a:b]
-	var uidx = e.Position - a
+func (e ErrMissingClose) Error() string {
+	// Underline 7 characters around.
+	var start = e.Position
 
 	errstr := strings.Builder{}
-	errstr.WriteString("Unexpected quote or escape")
+	errstr.WriteString("missing quote close")
 
-	// Do a bound check.
-	if uidx+1 > len(word) {
-		// Invalid.
-		errstr.WriteString(".")
-		return errstr.String()
+	if e.Words[start:] != "" {
+		errstr.WriteString(": ")
+		errstr.WriteString(escaper.Replace(e.Words[:start]))
+		errstr.WriteString("__")
+		errstr.WriteString(escaper.Replace(e.Words[start:]))
+		errstr.WriteString("__")
 	}
 
-	// Write the pre-underline part.
-	fmt.Fprintf(
-		&errstr, ": %s__%s__",
-		escaper.Replace(word[:uidx]),
-		escaper.Replace(string(word[uidx:])),
-	)
-
 	return errstr.String()
 }
 
@@ -117,7 +104,7 @@ func Parse(line string) ([]string, error) {
 	}
 
 	if escaped || singleQuoted || doubleQuoted {
-		return args, &ErrParse{
+		return args, ErrMissingClose{
 			Position: cursor + buf.Len(),
 			Words:    strings.Join(args, " "),
 		}
@@ -133,17 +120,3 @@ func isSpace(r rune) bool {
 	}
 	return false
 }
-
-func min(i, j int) int {
-	if i < j {
-		return i
-	}
-	return j
-}
-
-func max(i, j int) int {
-	if i < j {
-		return j
-	}
-	return i
-}

bot/extras/shellwords/shellwords_test.go

@@ -14,7 +14,17 @@ type wordsTest struct {
 func TestParse(t *testing.T) {
 	var tests = []wordsTest{
 		{
-			`this is a "test"`,
+			"",
+			nil,
+			false,
+		},
+		{
+			"'",
+			nil,
+			true,
+		},
+		{
+			`this is a "te""st"`,
 			[]string{"this", "is", "a", "test"},
 			false,
 		},