From 791126677d430c7ae0a44cc44c8ee5e2a8935582 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roland=20Lei=C3=9Fa?= <leissa@uni-mannheim.de>
Date: Fri, 18 Oct 2024 13:07:17 +0200
Subject: [PATCH] Cache in Lexer not needed anymore

---
 include/mim/ast/lexer.h |  7 +------
 src/mim/ast/lexer.cpp   | 38 ++++++--------------------------------
 2 files changed, 7 insertions(+), 38 deletions(-)

diff --git a/include/mim/ast/lexer.h b/include/mim/ast/lexer.h
index ffe59a326..efb7d5d3d 100644
--- a/include/mim/ast/lexer.h
+++ b/include/mim/ast/lexer.h
@@ -1,7 +1,5 @@
 #pragma once
 
-#include <optional>
-
 #include <absl/container/flat_hash_map.h>
 #include <fe/lexer.h>
 
@@ -23,7 +21,6 @@ class Lexer : public fe::Lexer<3, Lexer> {
 
     AST& ast() { return ast_; }
     const fs::path* path() const { return loc_.path; }
-    Loc loc() const { return loc_; }
     Tok lex();
 
 private:
@@ -41,9 +38,8 @@ class Lexer : public fe::Lexer<3, Lexer> {
         return res;
     }
 
-    Tok tok(Tok::Tag tag) { return {loc(), tag}; }
+    Tok tok(Tok::Tag tag) { return {loc_, tag}; }
     Sym sym();
-    Loc cache_trailing_dot();
     bool lex_id();
     char8_t lex_char();
     std::optional<Tok> parse_lit();
@@ -60,7 +56,6 @@ class Lexer : public fe::Lexer<3, Lexer> {
     std::ostream* md_;
     bool out_ = true;
     fe::SymMap<Tok::Tag> keywords_;
-    std::optional<Tok> cache_ = std::nullopt;
 
     friend class fe::Lexer<3, Lexer>;
 };
diff --git a/src/mim/ast/lexer.cpp b/src/mim/ast/lexer.cpp
index 3bf0734ce..186af4114 100644
--- a/src/mim/ast/lexer.cpp
+++ b/src/mim/ast/lexer.cpp
@@ -30,11 +30,6 @@ Lexer::Lexer(AST& ast, std::istream& istream, const fs::path* path /*= nullptr*/
 
 Tok Lexer::lex() {
     while (true) {
-        if (auto cache = cache_) {
-            cache_.reset();
-            return *cache;
-        }
-
         start();
 
         if (accept(utf8::EoF)) return tok(Tag::EoF);
@@ -90,22 +85,16 @@ Tok Lexer::lex() {
         // clang-format on
 
         if (accept('%')) {
-            if (lex_id()) {
-                auto loc = cache_trailing_dot();
-                return {loc, Tag::M_anx, sym()};
-            }
+            if (lex_id()) return {loc_, Tag::M_anx, sym()};
             ast().error(loc_, "invalid axiom name '{}'", str_);
+            continue;
         }
 
         if (accept('.')) {
             if (lex_id()) {
                 if (auto i = keywords_.find(sym()); i != keywords_.end()) return tok(i->second);
-                // Split non-keyword into T_dot and M_id; M_id goes into cache_ for next lex().
-                assert(!cache_.has_value());
-                auto id_loc = loc();
-                ++id_loc.begin.col;
-                cache_.emplace(id_loc, Tag::M_id, ast().sym(str_.substr(1)));
-                return {loc().anew_begin(), Tag::T_dot};
+                ast().error(loc_, "invalid keyword '{}'", str_);
+                continue;
             }
 
             if (accept(utf8::isdigit)) {
@@ -119,7 +108,7 @@ Tok Lexer::lex() {
 
         if (accept('\'')) {
             auto c = lex_char();
-            if (accept('\'')) return {loc(), c};
+            if (accept('\'')) return {loc_, c};
             ast().error(loc_, "invalid character literal {}", str_);
             continue;
         }
@@ -130,10 +119,7 @@ Tok Lexer::lex() {
             return {loc_, Tag::L_str, sym()};
         }
 
-        if (lex_id()) {
-            auto loc = cache_trailing_dot();
-            return {loc, Tag::M_id, sym()};
-        }
+        if (lex_id()) return {loc_, Tag::M_id, sym()};
 
         if (utf8::isdigit(ahead()) || utf8::any('+', '-')(ahead())) {
             if (auto lit = parse_lit()) return *lit;
@@ -165,18 +151,6 @@ Tok Lexer::lex() {
     }
 }
 
-// A trailing T_dot does not belong to an annex name or identifier and goes into cache_ for next lex().
-Loc Lexer::cache_trailing_dot() {
-    auto l = loc();
-    if (str_.back() == '.') {
-        str_.pop_back();
-        assert(!cache_.has_value());
-        cache_.emplace(l.anew_finis(), Tag::T_dot);
-        --l.finis.col;
-    }
-    return l;
-}
-
 bool Lexer::lex_id() {
     if (accept([](char32_t c) { return c == '_' || utf8::isalpha(c); })) {
         while (accept([](char32_t c) { return c == '_' || c == '.' || utf8::isalnum(c); })) {}