parser: introduce ErrPlusPosition to apply a position offset to a lexer.Error

Signed-off-by: Alejandro Mery <amery@jpi.io>

basic/error.go

@@ -16,7 +16,7 @@ func newErrInvalidToken(t *token) *lexer.Error {
 }
 
 func (dec *decoder) OnError(pos lexer.Position, content string, err error) error {
-	err = parser.NewError(pos, content, "", err)
+	err := parser.NewError(pos, content, "", err)
 	dec.executeFinal()
 	return err
 }

basic/token.go

@@ -32,21 +32,21 @@ func (dec *decoder) executeFinal() {
 func (dec *decoder) execute(typ parser.TokenType) {
 	switch typ {
 	case parser.TokenSectionEnd:
-		name1, ok1 := dec.queueValue(1, parser.TokenSectionName)
+		name1, ok1 := dec.getValue(1, parser.TokenSectionName)
 
 		if ok1 {
-			name2, ok2 := dec.queueValue(2, parser.TokenSectionSubname)
+			name2, ok2 := dec.getValue(2, parser.TokenSectionSubname)
 
 			dec.addSection(name1, name2, ok2)
 		}
 
-		dec.queueReset()
+		dec.reset()
 	case parser.TokenFieldValue:
-		key, _ := dec.queueValue(0, parser.TokenFieldKey)
-		value, _ := dec.queueValue(1, parser.TokenFieldValue)
+		key, _ := dec.getValue(0, parser.TokenFieldKey)
+		value, _ := dec.getValue(1, parser.TokenFieldValue)
 
 		dec.addField(key, value)
-		dec.queueReset()
+		dec.reset()
 	}
 }
 
@@ -82,8 +82,7 @@ func (dec *decoder) addField(key, value string) {
 	}
 }
 
-// queueValue extracts the value of element on the queue if the type matches.
-func (dec *decoder) queueValue(idx int, typ parser.TokenType) (string, bool) {
+func (dec *decoder) getValue(idx int, typ parser.TokenType) (string, bool) {
 	switch {
 	case idx < 0 || idx >= len(dec.queue):
 		// out of range
@@ -96,48 +95,40 @@ func (dec *decoder) queueValue(idx int, typ parser.TokenType) (string, bool) {
 	}
 }
 
-// queueReset removes all tokens from the queue
-func (dec *decoder) queueReset() {
+func (dec *decoder) reset() {
 	dec.queue = dec.queue[:0]
 }
 
-// queueDepth confirms the current depth of the queue
-func (dec *decoder) queueDepth(depth int) bool {
+func (dec *decoder) depth(depth int) bool {
 	return len(dec.queue) == depth
 }
 
-// queueDepthType confirms the current depth of the queue and the type of the last
-// element.
-func (dec *decoder) queueDepthType(depth int, typ parser.TokenType) bool {
-	if dec.queueDepth(depth) {
-		return dec.queueType(depth-1, typ)
+func (dec *decoder) depthAfter(depth int, typ parser.TokenType) bool {
+	_, ok := dec.getValue(depth-1, typ)
+	if ok {
+		return len(dec.queue) == depth
 	}
 	return false
 }
 
-// queueType tells if the specified element on the queue is of the required type.
-func (dec *decoder) queueType(idx int, typ parser.TokenType) bool {
-	_, ok := dec.queueValue(idx, typ)
-	return ok
-}
-
 func (dec *decoder) typeOK(typ parser.TokenType) bool {
 	switch typ {
 	case parser.TokenSectionStart, parser.TokenFieldKey:
 		// first token only
-		return dec.queueDepth(0)
+		return dec.depth(0)
 	case parser.TokenSectionName:
 		// right after TokenSectionStart
-		return dec.queueDepthType(1, parser.TokenSectionStart)
+		return dec.depthAfter(1, parser.TokenSectionStart)
 	case parser.TokenSectionSubname:
 		// right after TokenSectionName
-		return dec.queueDepthType(2, parser.TokenSectionName)
+		return dec.depthAfter(2, parser.TokenSectionName)
 	case parser.TokenSectionEnd:
 		// only on a section with name
-		return dec.queueType(1, parser.TokenSectionName)
+		_, ok := dec.getValue(1, parser.TokenSectionName)
+		return ok
 	case parser.TokenFieldValue:
 		// right after a TokenFieldKey
-		return dec.queueDepthType(1, parser.TokenFieldKey)
+		return dec.depthAfter(1, parser.TokenFieldKey)
 	default:
 		// never
 		return false
@@ -158,8 +149,6 @@ func (dec *decoder) OnToken(pos lexer.Position, typ parser.TokenType, value stri
 		return nil
 	default:
 		// unacceptable
-		err := newErrInvalidToken(t)
-		dec.executeFinal()
-		return err
+		return newErrInvalidToken(t)
 	}
 }