Added subscript lexer

orchid-std/src/std/ops/subscript_lexer.rs

@@ -0,0 +1,29 @@
+use orchid_base::error::OrcRes;
+use orchid_base::interner::is;
+use orchid_base::parse::{name_char, name_start};
+use orchid_extension::conv::ToExpr;
+use orchid_extension::lexer::{LexContext, LexedData, Lexer, err_not_applicable};
+use orchid_extension::tree::GenTok;
+
+use crate::std::string::str_atom::IntStrAtom;
+
+#[derive(Default, Debug)]
+pub struct SubscriptLexer;
+impl Lexer for SubscriptLexer {
+	const CHAR_FILTER: &'static [std::ops::RangeInclusive<char>] = &['.'..='.'];
+	async fn lex<'a>(tail: &'a str, lctx: &'a LexContext<'a>) -> OrcRes<(&'a str, impl LexedData)> {
+		if tail.len() <= 1 || !name_start(tail.chars().nth(1).unwrap()) {
+			return Err(err_not_applicable().await);
+		}
+		let name_len = match tail[1..].char_indices().find(|(_, c)| !name_char(*c)) {
+			None => tail.len() - 1,
+			Some((pos, _)) => pos,
+		};
+		let new_tail = &tail[name_len + 1..];
+		Ok((new_tail, [
+			GenTok::Name(is(".").await).at(lctx.pos_lt(1, &tail[1..])),
+			GenTok::NewExpr(IntStrAtom(is(&tail[1..name_len + 1]).await).to_gen().await)
+				.at(lctx.pos_tt(&tail[1..], new_tail)),
+		]))
+	}
+}