do not access parser state from error

src/cs_error.cc

@@ -2,7 +2,6 @@
 
 #include <algorithm>
 
-#include "cs_parser.hh"
 #include "cs_thread.hh"
 
 namespace cubescript {
@@ -49,26 +48,25 @@ LIBCUBESCRIPT_EXPORT char *error::request_buf(
 ) {
     auto &ts = state_p{cs}.ts();
     charbuf &cb = ts.errbuf;
-    parser_state *gs = ts.cstate;
     cb.clear();
     std::size_t sz = 0;
-    if (gs) {
+    if (ts.current_line) {
         /* we can attach line number */
-        sz = gs->src_name.size() + 32;
+        sz = ts.source.size() + 32;
         for (;;) {
             /* we are using so the buffer tracks the elements and therefore
              * does not wipe them when we attempt to reserve more capacity
              */
             cb.resize(sz);
             int nsz;
-            if (!gs->src_name.empty()) {
+            if (!ts.source.empty()) {
                 nsz = std::snprintf(
                     cb.data(), sz, "%.*s:%zu: ",
-                    int(gs->src_name.size()), gs->src_name.data(),
-                    gs->current_line
+                    int(ts.source.size()), ts.source.data(),
+                    *ts.current_line
                 );
             } else {
-                nsz = std::snprintf(cb.data(), sz, "%zu: ", gs->current_line);
+                nsz = std::snprintf(cb.data(), sz, "%zu: ", *ts.current_line);
             }
             if (nsz <= 0) {
                 throw internal_error{"format error"};

src/cs_gen.cc

@@ -431,10 +431,17 @@ void gen_state::gen_main(std::string_view v, std::string_view src) {
     parser_state ps{ts, *this};
     ps.source = v.data();
     ps.send = v.data() + v.size();
-    ps.src_name = src;
-    code.push_back(BC_INST_START);
-    ps.parse_block(VAL_ANY);
-    code.push_back(BC_INST_EXIT);
+    auto psrc = ts.source;
+    ts.source = src;
+    try {
+        code.push_back(BC_INST_START);
+        ps.parse_block(VAL_ANY);
+        code.push_back(BC_INST_EXIT);
+    } catch (...) {
+        ts.source = psrc;
+        throw;
+    }
+    ts.source = psrc;
 }
 
 void gen_state::gen_main_null() {

src/cs_parser.hh

@@ -23,26 +23,18 @@ bool is_valid_name(std::string_view input);
 struct parser_state {
     thread_state &ts;
     gen_state &gs;
-    parser_state *prevps;
-    bool parsing = true;
     char const *source, *send;
     std::size_t current_line;
-    std::string_view src_name;
 
     parser_state() = delete;
     parser_state(thread_state &tsr, gen_state &gsr):
-        ts{tsr}, gs{gsr}, prevps{tsr.cstate},
-        source{}, send{}, current_line{1}, src_name{}
+        ts{tsr}, gs{gsr}, source{}, send{}, current_line{1}
     {
-        tsr.cstate = this;
+        ts.current_line = &current_line;
     }
 
     ~parser_state() {
-        if (!parsing) {
-            return;
-        }
-        ts.cstate = prevps;
-        parsing = false;
+        ts.current_line = nullptr;
     }
 
     std::string_view get_str();

src/cs_thread.hh

@@ -11,8 +11,6 @@
 
 namespace cubescript {
 
-struct parser_state;
-
 struct thread_state {
     using astack_allocator = std_allocator<std::pair<int const, alias_stack>>;
     /* thread call stack */
@@ -21,8 +19,6 @@ struct thread_state {
     internal_state *istate{};
     /* the public state interface */
     state *pstate{};
-    /* current codegen state for diagnostics */
-    parser_state *cstate{};
     /* VM stack */
     valbuf<any_value> vmstack;
     /* ident stack */
@@ -45,6 +41,9 @@ struct thread_state {
     std::size_t run_depth = 0;
     /* loop nesting level */
     std::size_t loop_level = 0;
+    /* debug info */
+    std::string_view source{};
+    std::size_t *current_line = nullptr;
 
     thread_state(internal_state *cs);