diff --git a/parser/parser.go b/parser/parser.go
index 5d399fd..ab8b919 100644
--- a/parser/parser.go
+++ b/parser/parser.go
@@ -10,6 +10,49 @@ import (
 // Parser parses a dosini-style document
 type Parser struct {
 	src *lexer.Reader
+
+	OnSection func(pos lexer.Position, name, subname string, hasSubname bool) error
+	OnField   func(pos lexer.Position, key, value string) error
+	OnComment func(pos lexer.Position, comment string) error
+	OnError   func(pos lexer.Position, content string, err error) error
+}
+
+func defaultOnSection(_ lexer.Position, _, _ string, _ bool) error { return nil }
+func defaultOnField(_ lexer.Position, _, _ string) error           { return nil }
+func defaultOnComment(_ lexer.Position, _ string) error            { return nil }
+
+func defaultOnError(pos lexer.Position, content string, err error) error {
+	return &lexer.Error{
+		Line:    pos.Line,
+		Column:  pos.Column,
+		Content: content,
+		Err:     err,
+	}
+}
+
+func (p *Parser) setDefaults() {
+	if p.OnSection == nil {
+		p.OnSection = defaultOnSection
+	}
+
+	if p.OnField == nil {
+		p.OnField = defaultOnField
+	}
+
+	if p.OnComment == nil {
+		p.OnComment = defaultOnComment
+	}
+
+	if p.OnError == nil {
+		p.OnError = defaultOnError
+	}
+}
+
+// Run parses the source
+func (p *Parser) Run() error {
+	p.setDefaults()
+
+	return lexer.Run(p.initialState)
 }
 
 // NewParser creates a dosini-style parser using
diff --git a/parser/states.go b/parser/states.go
new file mode 100644
index 0000000..166f21b
--- /dev/null
+++ b/parser/states.go
@@ -0,0 +1,7 @@
+package parser
+
+import "asciigoat.org/core/lexer"
+
+func (*Parser) initialState() (lexer.StateFn, error) {
+	return nil, nil
+}