lang: rewrite parser

crates/lang/src/parser/grammar/expression.rs

@@ -0,0 +1,14 @@
+use crate::parser::{syntax_kind::SyntaxKind::*, Parser};
+
+use self::{instruction::instr, lit::literal};
+
+mod instruction;
+mod lit;
+
+pub fn expression(p: &mut Parser) {
+    let expr = p.start();
+
+    instr(p);
+
+    expr.complete(p, EXPR);
+}

crates/lang/src/parser/grammar/expression/instruction.rs

@@ -0,0 +1,30 @@
+use crate::parser::{syntax_kind::SyntaxKind::*, Parser};
+
+use super::lit::literal;
+
+pub fn instr(p: &mut Parser) {
+    let instr = p.start();
+
+    instr_name(p);
+    instr_params(p);
+
+    instr.complete(p, INSTR);
+}
+
+fn instr_name(p: &mut Parser) {
+    let instr_name = p.start();
+
+    while p.at(IDENT) {
+        p.do_bump();
+    }
+
+    instr_name.complete(p, INSTR_NAME);
+}
+
+fn instr_params(p: &mut Parser) {
+    if let Some(start) = literal(p) {
+        while literal(p).is_some() {}
+
+        start.precede(p).complete(p, INSTR_PARAMS);
+    }
+}

crates/lang/src/parser/grammar/expression/lit.rs

@@ -0,0 +1,20 @@
+use enumset::enum_set;
+
+use crate::parser::{
+    syntax_kind::{SyntaxKind::*, TokenSet},
+    CompletedMarker, Parser,
+};
+
+const LIT_TOKENS: TokenSet = enum_set!(INT_NUM | FLOAT_NUM | STRING);
+
+pub fn literal(p: &mut Parser) -> Option<CompletedMarker> {
+    if !LIT_TOKENS.contains(p.current()) {
+        return None;
+    }
+
+    let lit = p.start();
+
+    p.do_bump();
+
+    Some(lit.complete(p, LITERAL))
+}