parser: add initial Parser emitting non-whitespace tokens

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

parser/lexer_runes.go

@@ -0,0 +1,16 @@
+package parser
+
+import (
+	"asciigoat.org/core/lexer"
+)
+
+var (
+	// IsNewLine tells if the rune indicates a line break or the start of one
+	IsNewLine = lexer.NewIsIn("\r\n")
+	// IsNotNewLine tells if the rune is not a line break nor the start of one
+	IsNotNewLine = lexer.NewIsNot(IsNewLine)
+	// IsSpace tells if the rune is considered whitespace by Unicode
+	IsSpace = lexer.IsSpace
+	// IsNotSpace tells if the rune is not considered whitespace by Unicode
+	IsNotSpace = lexer.NewIsNot(IsSpace)
+)