Optimize calls to Z3_eval_smtlib2_string (#6422)

* Allow reseting the stream of smt2::scanner

* Put the parser of parse_smt2_commands in the cmd_context

* Move parser streams to cmd_context

* Move parser fields from cmd_context to api::context

* Move forward declarations from cmd_context.h to api_context.h

* Change parse_smt2_commands_with_parser to use *& instead of **

* Add tests for Z3_eval_smtlib2_string

* Don't reuse the streams in Z3_eval_smtlib2_string

* Fix indentation

* Add back unnecessary deleted line

Co-authored-by: Nuno Lopes <nuno.lopes@tecnico.ulisboa.pt>

src/parsers/smt2/smt2parser.cpp

@@ -3105,6 +3105,10 @@ namespace smt2 {
 
         }
 
+        void reset_input(std::istream & is, bool interactive) {
+            m_scanner.reset_input(is, interactive);
+        }
+
         sexpr_ref parse_sexpr_ref() {
             m_num_bindings    = 0;
             m_num_open_paren = 0;
@@ -3204,6 +3208,8 @@ namespace smt2 {
             }
         }
     };
+
+    void free_parser(parser * p) { dealloc(p); }
 };
 
 bool parse_smt2_commands(cmd_context & ctx, std::istream & is, bool interactive, params_ref const & ps, char const * filename) {
@@ -3211,6 +3217,14 @@ bool parse_smt2_commands(cmd_context & ctx, std::istream & is, bool interactive,
     return p();
 }
 
+bool parse_smt2_commands_with_parser(class smt2::parser *& p, cmd_context & ctx, std::istream & is, bool interactive, params_ref const & ps, char const * filename) {
+    if (p)
+        p->reset_input(is, interactive);
+    else
+        p = alloc(smt2::parser, ctx, is, interactive, ps, filename);
+    return (*p)();
+}
+
 sort_ref parse_smt2_sort(cmd_context & ctx, std::istream & is, bool interactive, params_ref const & ps, char const * filename) {
     smt2::parser p(ctx, is, interactive, ps, filename);
     return p.parse_sort_ref(filename);

src/parsers/smt2/smt2parser.h

@@ -20,7 +20,14 @@ Revision History:
 
 #include "cmd_context/cmd_context.h"
 
-bool parse_smt2_commands(cmd_context & ctx, std::istream & is, bool interactive = false, params_ref const & p = params_ref(), char const * filename = nullptr);
+namespace smt2 {
+    class parser;
+    void free_parser(parser * p);
+}
+
+bool parse_smt2_commands(cmd_context & ctx, std::istream & is, bool interactive = false, params_ref const & ps = params_ref(), char const * filename = nullptr);
+
+bool parse_smt2_commands_with_parser(class smt2::parser *& p, cmd_context & ctx, std::istream & is, bool interactive = false, params_ref const & ps = params_ref(), char const * filename = nullptr);
 
 sexpr_ref parse_sexpr(cmd_context& ctx, std::istream& is, params_ref const& ps, char const* filename);
 

src/parsers/smt2/smt2scanner.cpp

@@ -27,8 +27,8 @@ namespace smt2 {
         if (m_at_eof)
             throw scanner_exception("unexpected end of file");
         if (m_interactive) {
-            m_curr = m_stream.get();
-            if (m_stream.eof())
+            m_curr = m_stream->get();
+            if (m_stream->eof())
                 m_at_eof = true;
         }
         else if (m_bpos < m_bend) {
@@ -36,8 +36,8 @@ namespace smt2 {
             m_bpos++;
         }
         else {
-            m_stream.read(m_buffer, SCANNER_BUFFER_SIZE);
-            m_bend = static_cast<unsigned>(m_stream.gcount());
+            m_stream->read(m_buffer, SCANNER_BUFFER_SIZE);
+            m_bend = static_cast<unsigned>(m_stream->gcount());
             m_bpos = 0;
             if (m_bpos == m_bend) {
                 m_at_eof = true;
@@ -281,7 +281,7 @@ namespace smt2 {
         m_bv_size(UINT_MAX),
         m_bpos(0),
         m_bend(0),
-        m_stream(stream),
+        m_stream(&stream),
         m_cache_input(false) {
 
 
@@ -390,5 +390,13 @@ namespace smt2 {
         return m_cache_result.begin();
     }
 
+    void scanner::reset_input(std::istream & stream, bool interactive) {
+        m_stream = &stream;
+        m_interactive = interactive;
+        m_at_eof = false;
+        m_bpos = 0;
+        m_bend = 0;
+        next();
+    }
 };
 

src/parsers/smt2/smt2scanner.h

@@ -49,7 +49,7 @@ namespace smt2 {
         unsigned           m_bpos;
         unsigned           m_bend;
         svector<char>      m_string;
-        std::istream&      m_stream;
+        std::istream*      m_stream;
         
         bool               m_cache_input;
         svector<char>      m_cache;
@@ -99,6 +99,7 @@ namespace smt2 {
         void stop_caching() { m_cache_input = false; }
         unsigned cache_size() const { return m_cache.size(); }
         void reset_cache() { m_cache.reset(); }
+        void reset_input(std::istream & stream, bool interactive = false);
 
         char const * cached_str(unsigned begin, unsigned end);
     };