lexer: create Lexer factories for io.Reader, []byte and string

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

lexer/lexer.go

@@ -1,7 +1,11 @@
 // Package lexer provides basic helpers to implement parsers
 package lexer
 
-import "io"
+import (
+	"io"
+
+	"asciigoat.org/core/runes"
+)
 
 // Lexer adds Accept and AcceptAll support to a
 // [io.RuneScanner]
@@ -32,6 +36,25 @@ func NewLexer(src io.RuneScanner) *Lexer {
 	return &Lexer{src}
 }
 
+// NewLexerReader creates a Lexer from an [io.Reader]
+func NewLexerReader(r io.Reader) *Lexer {
+	if r == nil {
+		return nil
+	}
+
+	return &Lexer{runes.NewReader(r)}
+}
+
+// NewLexerBytes creates a Lexer from raw bytes
+func NewLexerBytes(b []byte) *Lexer {
+	return &Lexer{runes.NewReaderBytes(b)}
+}
+
+// NewLexerString creates a Lexer from a data string
+func NewLexerString(s string) *Lexer {
+	return &Lexer{runes.NewReaderString(s)}
+}
+
 // StateFn is a State Function of the parser
 type StateFn func() (StateFn, error)