Merge pull request #760 from nats-io/config-report-pos

Report position of configuration errors

conf/lex.go

@@ -101,12 +101,19 @@ type lexer struct {
 	// Used for processing escapable substrings in double-quoted and raw strings
 	stringParts   []string
 	stringStateFn stateFn
+
+	// lstart is the start position of the current line.
+	lstart int
+
+	// ilstart is the start position of the line from the current item.
+	ilstart int
 }
 
 type item struct {
 	typ  itemType
 	val  string
 	line int
+	pos  int
 }
 
 func (lx *lexer) nextItem() item {
@@ -147,8 +154,13 @@ func (lx *lexer) pop() stateFn {
 }
 
 func (lx *lexer) emit(typ itemType) {
-	lx.items <- item{typ, strings.Join(lx.stringParts, "") + lx.input[lx.start:lx.pos], lx.line}
+	val := strings.Join(lx.stringParts, "") + lx.input[lx.start:lx.pos]
+
+	// Position of item in line where it started.
+	pos := lx.pos - lx.ilstart - len(val)
+	lx.items <- item{typ, val, lx.line, pos}
 	lx.start = lx.pos
+	lx.ilstart = lx.lstart
 }
 
 func (lx *lexer) emitString() {
@@ -159,8 +171,11 @@ func (lx *lexer) emitString() {
 	} else {
 		finalString = lx.input[lx.start:lx.pos]
 	}
-	lx.items <- item{itemString, finalString, lx.line}
+	// Position of string in line where it started.
+	pos := lx.pos - lx.ilstart - len(finalString)
+	lx.items <- item{itemString, finalString, lx.line, pos}
 	lx.start = lx.pos
+	lx.ilstart = lx.lstart
 }
 
 func (lx *lexer) addCurrentStringPart(offset int) {
@@ -186,15 +201,20 @@ func (lx *lexer) next() (r rune) {
 
 	if lx.input[lx.pos] == '\n' {
 		lx.line++
+
+		// Mark start position of current line.
+		lx.lstart = lx.pos
 	}
 	r, lx.width = utf8.DecodeRuneInString(lx.input[lx.pos:])
 	lx.pos += lx.width
+
 	return r
 }
 
 // ignore skips over the pending input before this point.
 func (lx *lexer) ignore() {
 	lx.start = lx.pos
+	lx.ilstart = lx.lstart
 }
 
 // backup steps back one rune. Can be called only once per call of next.
@@ -221,10 +241,14 @@ func (lx *lexer) errorf(format string, values ...interface{}) stateFn {
 			values[i] = escapeSpecial(v)
 		}
 	}
+
+	// Position of error in current line.
+	pos := lx.pos - lx.lstart
 	lx.items <- item{
 		itemError,
 		fmt.Sprintf(format, values...),
 		lx.line,
+		pos,
 	}
 	return nil
 }
@@ -1131,7 +1155,7 @@ func (itype itemType) String() string {
 }
 
 func (item item) String() string {
-	return fmt.Sprintf("(%s, '%s', %d)", item.typ.String(), item.val, item.line)
+	return fmt.Sprintf("(%s, '%s', %d, %d)", item.typ.String(), item.val, item.line, item.pos)
 }
 
 func escapeSpecial(c rune) string {