lexer: introduce Lexer wrapper for io.RuneScanner

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

lexer/lexer.go

@@ -3,6 +3,35 @@ package lexer
 
 import "io"
 
+// Lexer adds Accept and AcceptAll support to a
+// [io.RuneScanner]
+type Lexer struct {
+	io.RuneScanner
+}
+
+// Accept consumes a rune from the source if it meets the condition.
+// it returns true if the condition was met and false if it wasn't.
+func (p Lexer) Accept(cond func(rune) bool) bool {
+	return Accept(p, cond)
+}
+
+// AcceptAll consumes runes from the source as long as they meet the
+// condition. it returns true if the condition was met for at least one rune,
+// and false if it wasn't.
+func (p Lexer) AcceptAll(cond func(rune) bool) bool {
+	return AcceptAll(p, cond)
+}
+
+// NewLexer extends a [io.RuneScanner] with Accept()/AcceptAll()
+// functionality
+func NewLexer(src io.RuneScanner) *Lexer {
+	if src == nil {
+		return nil
+	}
+
+	return &Lexer{src}
+}
+
 // StateFn is a State Function of the parser
 type StateFn func() (StateFn, error)