Add validation of smt parse trees to construct smt_responset instances.

src/solvers/Makefile

@@ -199,6 +199,7 @@ SRC = $(BOOLEFORCE_SRC) \
       smt2_incremental/smt_core_theory.cpp \
       smt2_incremental/smt_logics.cpp \
       smt2_incremental/smt_options.cpp \
+      smt2_incremental/smt_response_validation.cpp \
       smt2_incremental/smt_responses.cpp \
       smt2_incremental/smt_solver_process.cpp \
       smt2_incremental/smt_sorts.cpp \

src/solvers/smt2_incremental/smt_response_validation.cpp

@@ -0,0 +1,328 @@
+// Author: Diffblue Ltd.
+
+/// \file
+///
+/// Validation of smt response parse trees to produce either a strongly typed
+/// `smt_responset` representation, or a set of error messages.
+///
+/// \note
+///
+/// Functions named with the prefix `validate_` require the given parse tree to
+/// be a particular kind of sub tree. Functions named with the prefix `valid_`
+/// are called in places where the exact kind of sub-tree expected is unknown
+/// and so the function must determine if the sub-tree is of that type at all,
+/// before performing validation of it. These functions will return a
+/// `response_or_errort` in the case where the parse tree is of that type or
+/// an empty optional otherwise.
+
+#include <solvers/smt2_incremental/smt_response_validation.h>
+
+#include <util/mp_arith.h>
+#include <util/range.h>
+
+#include <regex>
+
+template <class smtt>
+response_or_errort<smtt>::response_or_errort(smtt smt) : smt{std::move(smt)}
+{
+}
+
+template <class smtt>
+response_or_errort<smtt>::response_or_errort(std::string message)
+  : messages{std::move(message)}
+{
+}
+
+template <class smtt>
+response_or_errort<smtt>::response_or_errort(std::vector<std::string> messages)
+  : messages{std::move(messages)}
+{
+}
+
+template <class smtt>
+const smtt *response_or_errort<smtt>::get_if_valid() const
+{
+  INVARIANT(
+    smt.has_value() == messages.empty(),
+    "The response_or_errort class must be in the valid state or error state, "
+    "exclusively.");
+  return smt.has_value() ? &smt.value() : nullptr;
+}
+
+template <class smtt>
+const std::vector<std::string> *response_or_errort<smtt>::get_if_error() const
+{
+  INVARIANT(
+    smt.has_value() == messages.empty(),
+    "The response_or_errort class must be in the valid state or error state, "
+    "exclusively.");
+  return smt.has_value() ? nullptr : &messages;
+}
+
+template class response_or_errort<smt_responset>;
+
+// Implementation detail of `collect_messages` below.
+template <typename argumentt, typename... argumentst>
+void collect_messages_impl(
+  std::vector<std::string> &collected_messages,
+  argumentt &&argument)
+{
+  if(const auto messages = argument.get_if_error())
+  {
+    collected_messages.insert(
+      collected_messages.end(), messages->cbegin(), messages->end());
+  }
+}
+
+// Implementation detail of `collect_messages` below.
+template <typename argumentt, typename... argumentst>
+void collect_messages_impl(
+  std::vector<std::string> &collected_messages,
+  argumentt &&argument,
+  argumentst &&... arguments)
+{
+  collect_messages_impl(collected_messages, argument);
+  collect_messages_impl(collected_messages, arguments...);
+}
+
+/// Builds a collection of messages composed all messages in the
+/// `response_or_errort` typed arguments in \p arguments. This is a templated
+/// function in order to handle `response_or_errort` instances which are
+/// specialised differently.
+template <typename... argumentst>
+std::vector<std::string> collect_messages(argumentst &&... arguments)
+{
+  std::vector<std::string> collected_messages;
+  collect_messages_impl(collected_messages, arguments...);
+  return collected_messages;
+}
+
+/// \brief Given a class to construct and a set of arguments to its constructor
+///   which may include errors, either return the collected errors if there are
+///   any or construct the class otherwise.
+/// \tparam smt_to_constructt
+///   The class to construct.
+/// \tparam smt_baset
+///   If the class to construct should be upcast to a base class before being
+///   stored in the `response_or_errort`, then the base class should be supplied
+///   in this parameter. If no upcast is required, then this should be left
+///   empty.
+/// \tparam argumentst
+///   The pack of argument types matching the constructor of
+///   `smt_to_constructt`. These must each be packed into an instance of
+///   `response_or_errort`.
+template <
+  typename smt_to_constructt,
+  typename smt_baset = smt_to_constructt,
+  typename... argumentst>
+response_or_errort<smt_baset> validation_propagating(argumentst &&... arguments)
+{
+  const auto collected_messages = collect_messages(arguments...);
+  if(!collected_messages.empty())
+    return response_or_errort<smt_baset>(collected_messages);
+  else
+  {
+    return response_or_errort<smt_baset>{
+      smt_to_constructt{(*arguments.get_if_valid())...}};
+  }
+}
+
+/// Produces a human-readable representation of the given \p parse_tree, for use
+/// in error messaging.
+/// \note This is currently implemented using `pretty`, but this function is
+///   used instead of calling `pretty` directly so that will be more straight
+///   forward to replace with an implementation specific to our use case which
+///   is more easily readable by users of CBMC.
+static std::string print_parse_tree(const irept &parse_tree)
+{
+  return parse_tree.pretty(0, 0);
+}
+
+static response_or_errort<irep_idt>
+validate_string_literal(const irept &parse_tree)
+{
+  if(!parse_tree.get_sub().empty())
+  {
+    return response_or_errort<irep_idt>(
+      "Expected string literal, found \"" + print_parse_tree(parse_tree) +
+      "\".");
+  }
+  return response_or_errort<irep_idt>{parse_tree.id()};
+}
+
+/// \returns: A response or error in the case where the parse tree appears to be
+///   a get-value command. Returns empty otherwise.
+/// \note: Because this kind of response does not start with an identifying
+///   keyword, it will be considered that the response is intended to be a
+///   get-value response if it is composed of a collection of one or more pairs.
+static optionalt<response_or_errort<smt_responset>>
+valid_smt_error_response(const irept &parse_tree)
+{
+  // Check if the parse tree looks to be an error response.
+  if(!parse_tree.id().empty())
+    return {};
+  if(parse_tree.get_sub().empty())
+    return {};
+  if(parse_tree.get_sub().at(0).id() != "error")
+    return {};
+  // Parse tree is now considered to be an error response and anything
+  // unexpected in the parse tree is now considered to be an invalid response.
+  if(parse_tree.get_sub().size() == 1)
+  {
+    return {response_or_errort<smt_responset>{
+      "Error response is missing the error message."}};
+  }
+  if(parse_tree.get_sub().size() > 2)
+  {
+    return {response_or_errort<smt_responset>{
+      "Error response has multiple error messages - \"" +
+      print_parse_tree(parse_tree) + "\"."}};
+  }
+  return validation_propagating<smt_error_responset, smt_responset>(
+    validate_string_literal(parse_tree.get_sub()[1]));
+}
+
+static bool all_subs_are_pairs(const irept &parse_tree)
+{
+  return std::all_of(
+    parse_tree.get_sub().cbegin(),
+    parse_tree.get_sub().cend(),
+    [](const irept &sub) { return sub.get_sub().size() == 2; });
+}
+
+static response_or_errort<irep_idt>
+validate_smt_identifier(const irept &parse_tree)
+{
+  if(!parse_tree.get_sub().empty() || parse_tree.id().empty())
+  {
+    return response_or_errort<irep_idt>(
+      "Expected identifier, found - \"" + print_parse_tree(parse_tree) + "\".");
+  }
+  return response_or_errort<irep_idt>(parse_tree.id());
+}
+
+static optionalt<smt_termt> valid_smt_bool(const irept &parse_tree)
+{
+  if(!parse_tree.get_sub().empty())
+    return {};
+  if(parse_tree.id() == ID_true)
+    return {smt_bool_literal_termt{true}};
+  if(parse_tree.id() == ID_false)
+    return {smt_bool_literal_termt{false}};
+  return {};
+}
+
+static optionalt<smt_termt> valid_smt_binary(const std::string &text)
+{
+  static const std::regex binary_format{"#b[01]+"};
+  if(!std::regex_match(text, binary_format))
+    return {};
+  const mp_integer value = string2integer({text.begin() + 2, text.end()}, 2);
+  // Width is number of bit values minus the "#b" prefix.
+  const std::size_t width = text.size() - 2;
+  return {smt_bit_vector_constant_termt{value, width}};
+}
+
+static optionalt<smt_termt> valid_smt_hex(const std::string &text)
+{
+  static const std::regex hex_format{"#x[0-9A-Za-z]+"};
+  if(!std::regex_match(text, hex_format))
+    return {};
+  const std::string hex{text.begin() + 2, text.end()};
+  // SMT-LIB 2 allows hex characters to be upper of lower case, but they should
+  // be upper case for mp_integer.
+  const mp_integer value =
+    string2integer(make_range(hex).map<std::function<int(int)>>(toupper), 16);
+  const std::size_t width = (text.size() - 2) * 4;
+  return {smt_bit_vector_constant_termt{value, width}};
+}
+
+static optionalt<smt_termt>
+valid_smt_bit_vector_constant(const irept &parse_tree)
+{
+  if(!parse_tree.get_sub().empty() || parse_tree.id().empty())
+    return {};
+  const auto value_string = id2string(parse_tree.id());
+  if(const auto smt_binary = valid_smt_binary(value_string))
+    return *smt_binary;
+  if(const auto smt_hex = valid_smt_hex(value_string))
+    return *smt_hex;
+  return {};
+}
+
+static response_or_errort<smt_termt> validate_term(const irept &parse_tree)
+{
+  if(const auto smt_bool = valid_smt_bool(parse_tree))
+    return response_or_errort<smt_termt>{*smt_bool};
+  if(const auto bit_vector_constant = valid_smt_bit_vector_constant(parse_tree))
+    return response_or_errort<smt_termt>{*bit_vector_constant};
+  return response_or_errort<smt_termt>{"Unrecognised SMT term - \"" +
+                                       print_parse_tree(parse_tree) + "\"."};
+}
+
+static response_or_errort<smt_get_value_responset::valuation_pairt>
+validate_valuation_pair(const irept &pair_parse_tree)
+{
+  PRECONDITION(pair_parse_tree.get_sub().size() == 2);
+  const auto &descriptor = pair_parse_tree.get_sub()[0];
+  const auto &value = pair_parse_tree.get_sub()[1];
+  return validation_propagating<smt_get_value_responset::valuation_pairt>(
+    validate_smt_identifier(descriptor), validate_term(value));
+}
+
+/// \returns: A response or error in the case where the parse tree appears to be
+///   a get-value command. Returns empty otherwise.
+/// \note: Because this kind of response does not start with an identifying
+///   keyword, it will be considered that the response is intended to be a
+///   get-value response if it is composed of a collection of one or more pairs.
+static optionalt<response_or_errort<smt_responset>>
+valid_smt_get_value_response(const irept &parse_tree)
+{
+  // Shape matching for does this look like a get value response?
+  if(!parse_tree.id().empty())
+    return {};
+  if(parse_tree.get_sub().empty())
+    return {};
+  if(!all_subs_are_pairs(parse_tree))
+    return {};
+  std::vector<std::string> error_messages;
+  std::vector<smt_get_value_responset::valuation_pairt> valuation_pairs;
+  for(const auto &pair : parse_tree.get_sub())
+  {
+    const auto pair_validation_result = validate_valuation_pair(pair);
+    if(const auto error = pair_validation_result.get_if_error())
+      error_messages.insert(error_messages.end(), error->begin(), error->end());
+    if(const auto valid_pair = pair_validation_result.get_if_valid())
+      valuation_pairs.push_back(*valid_pair);
+  }
+  if(!error_messages.empty())
+    return {response_or_errort<smt_responset>{std::move(error_messages)}};
+  else
+  {
+    return {response_or_errort<smt_responset>{
+      smt_get_value_responset{valuation_pairs}}};
+  }
+}
+
+response_or_errort<smt_responset> validate_smt_response(const irept &parse_tree)
+{
+  if(parse_tree.id() == "sat")
+    return response_or_errort<smt_responset>{
+      smt_check_sat_responset{smt_sat_responset{}}};
+  if(parse_tree.id() == "unsat")
+    return response_or_errort<smt_responset>{
+      smt_check_sat_responset{smt_unsat_responset{}}};
+  if(parse_tree.id() == "unknown")
+    return response_or_errort<smt_responset>{
+      smt_check_sat_responset{smt_unknown_responset{}}};
+  if(const auto error_response = valid_smt_error_response(parse_tree))
+    return *error_response;
+  if(parse_tree.id() == "success")
+    return response_or_errort<smt_responset>{smt_success_responset{}};
+  if(parse_tree.id() == "unsupported")
+    return response_or_errort<smt_responset>{smt_unsupported_responset{}};
+  if(const auto get_value_response = valid_smt_get_value_response(parse_tree))
+    return *get_value_response;
+  return response_or_errort<smt_responset>{"Invalid SMT response \"" +
+                                           id2string(parse_tree.id()) + "\""};
+}

src/solvers/smt2_incremental/smt_response_validation.h

@@ -0,0 +1,43 @@
+// Author: Diffblue Ltd.
+
+#ifndef CPROVER_SOLVERS_SMT2_INCREMENTAL_SMT_RESPONSE_VALIDATION_H
+#define CPROVER_SOLVERS_SMT2_INCREMENTAL_SMT_RESPONSE_VALIDATION_H
+
+#include <solvers/smt2_incremental/smt_responses.h>
+#include <util/invariant.h>
+#include <util/optional.h>
+
+#include <string>
+#include <vector>
+
+/// Holds either a valid parsed response or response sub-tree of type \tparam
+/// smtt or a collection of message strings explaining why the given input was
+/// not valid.
+template <class smtt>
+class response_or_errort final
+{
+public:
+  explicit response_or_errort(smtt smt);
+  explicit response_or_errort(std::string message);
+  explicit response_or_errort(std::vector<std::string> messages);
+
+  /// \brief Gets the smt response if the response is valid, or returns nullptr
+  ///   otherwise.
+  const smtt *get_if_valid() const;
+  /// \brief Gets the error messages if the response is invalid, or returns
+  ///   nullptr otherwise.
+  const std::vector<std::string> *get_if_error() const;
+
+private:
+  // The below two fields could be a single `std::variant` field, if there was
+  // an implementation of it available in the cbmc repository. However at the
+  // time of writing we are targeting C++11, `std::variant` was introduced in
+  // C++17 and we have no backported version.
+  optionalt<smtt> smt;
+  std::vector<std::string> messages;
+};
+
+response_or_errort<smt_responset>
+validate_smt_response(const irept &parse_tree);
+
+#endif // CPROVER_SOLVERS_SMT2_INCREMENTAL_SMT_RESPONSE_VALIDATION_H