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Diffstat (limited to 'src/vtab_module.hh')
| -rw-r--r-- | src/vtab_module.hh | 929 |
1 files changed, 929 insertions, 0 deletions
diff --git a/src/vtab_module.hh b/src/vtab_module.hh new file mode 100644 index 0000000..a45594c --- /dev/null +++ b/src/vtab_module.hh @@ -0,0 +1,929 @@ +/** + * Copyright (c) 2017, Timothy Stack + * + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * * Redistributions of source code must retain the above copyright notice, this + * list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright notice, + * this list of conditions and the following disclaimer in the documentation + * and/or other materials provided with the distribution. + * * Neither the name of Timothy Stack nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ''AS IS'' AND ANY + * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE + * DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#ifndef vtab_module_hh +#define vtab_module_hh + +#include <string> +#include <utility> +#include <vector> + +#include <sqlite3.h> + +#include "base/auto_mem.hh" +#include "base/intern_string.hh" +#include "base/lnav.console.hh" +#include "base/lnav_log.hh" +#include "base/string_util.hh" +#include "fmt/format.h" +#include "help_text_formatter.hh" +#include "mapbox/variant.hpp" +#include "optional.hpp" +#include "shlex.resolver.hh" +#include "sqlite-extension-func.hh" + +lnav::console::user_message sqlite3_error_to_user_message(sqlite3*); + +struct from_sqlite_conversion_error : std::exception { + from_sqlite_conversion_error(const char* type, int argi) + : e_type(type), e_argi(argi) + { + } + + const char* e_type; + int e_argi; +}; + +struct sqlite_func_error : std::exception { + template<typename... Args> + explicit sqlite_func_error(fmt::string_view format_str, const Args&... args) + : e_what(fmt::vformat(format_str, fmt::make_format_args(args...))) + { + } + + const char* what() const noexcept override + { + return this->e_what.c_str(); + } + + const std::string e_what; +}; + +namespace vtab_types { + +template<typename T> +struct nullable { + T* n_value{nullptr}; +}; + +template<typename> +struct is_nullable : std::false_type { +}; + +template<typename T> +struct is_nullable<nullable<T>> : std::true_type { +}; + +} // namespace vtab_types + +template<typename T> +struct from_sqlite { + using U = typename std::remove_reference<T>::type; + + inline U operator()(int argc, sqlite3_value** val, int argi) + { + return U(); + }; +}; + +template<> +struct from_sqlite<bool> { + inline bool operator()(int argc, sqlite3_value** val, int argi) + { + if (sqlite3_value_numeric_type(val[argi]) != SQLITE_INTEGER) { + throw from_sqlite_conversion_error("integer", argi); + } + + return sqlite3_value_int64(val[argi]); + } +}; + +template<> +struct from_sqlite<int64_t> { + inline int64_t operator()(int argc, sqlite3_value** val, int argi) + { + if (sqlite3_value_numeric_type(val[argi]) != SQLITE_INTEGER) { + throw from_sqlite_conversion_error("integer", argi); + } + + return sqlite3_value_int64(val[argi]); + } +}; + +template<> +struct from_sqlite<sqlite3_value*> { + inline sqlite3_value* operator()(int argc, sqlite3_value** val, int argi) + { + return val[argi]; + } +}; + +template<> +struct from_sqlite<int> { + inline int operator()(int argc, sqlite3_value** val, int argi) + { + if (sqlite3_value_numeric_type(val[argi]) != SQLITE_INTEGER) { + throw from_sqlite_conversion_error("integer", argi); + } + + return sqlite3_value_int(val[argi]); + } +}; + +template<> +struct from_sqlite<const char*> { + inline const char* operator()(int argc, sqlite3_value** val, int argi) + { + return (const char*) sqlite3_value_text(val[argi]); + } +}; + +template<> +struct from_sqlite<string_fragment> { + inline string_fragment operator()(int argc, sqlite3_value** val, int argi) + { + return string_fragment::from_bytes( + (const char*) sqlite3_value_blob(val[argi]), + sqlite3_value_bytes(val[argi])); + } +}; + +template<> +struct from_sqlite<std::string> { + inline std::string operator()(int argc, sqlite3_value** val, int argi) + { + return { + (const char*) sqlite3_value_blob(val[argi]), + (size_t) sqlite3_value_bytes(val[argi]), + }; + } +}; + +template<> +struct from_sqlite<double> { + inline double operator()(int argc, sqlite3_value** val, int argi) + { + return sqlite3_value_double(val[argi]); + } +}; + +template<typename T> +struct from_sqlite<nonstd::optional<T>> { + inline nonstd::optional<T> operator()(int argc, + sqlite3_value** val, + int argi) + { + if (argi >= argc || sqlite3_value_type(val[argi]) == SQLITE_NULL) { + return nonstd::nullopt; + } + + return nonstd::optional<T>(from_sqlite<T>()(argc, val, argi)); + } +}; + +template<typename T> +struct from_sqlite<const std::vector<T>&> { + inline std::vector<T> operator()(int argc, sqlite3_value** val, int argi) + { + std::vector<T> retval; + + for (int lpc = argi; lpc < argc; lpc++) { + retval.emplace_back(from_sqlite<T>()(argc, val, lpc)); + } + + return retval; + } +}; + +template<typename T> +struct from_sqlite<vtab_types::nullable<T>> { + inline vtab_types::nullable<T> operator()(int argc, + sqlite3_value** val, + int argi) + { + return {from_sqlite<T*>()(argc, val, argi)}; + } +}; + +void to_sqlite(sqlite3_context* ctx, const lnav::console::user_message& um); + +inline void +to_sqlite(sqlite3_context* ctx, null_value_t) +{ + sqlite3_result_null(ctx); +} + +inline void +to_sqlite(sqlite3_context* ctx, const char* str) +{ + if (str == nullptr) { + sqlite3_result_null(ctx); + } else { + sqlite3_result_text(ctx, str, -1, SQLITE_STATIC); + } +} + +inline void +to_sqlite(sqlite3_context* ctx, text_auto_buffer buf) +{ + auto pair = buf.inner.release(); + sqlite3_result_text(ctx, pair.first, pair.second, free); +} + +inline void +to_sqlite(sqlite3_context* ctx, blob_auto_buffer buf) +{ + auto pair = buf.inner.release(); + sqlite3_result_blob(ctx, pair.first, pair.second, free); +} + +inline void +to_sqlite(sqlite3_context* ctx, const std::string& str) +{ + sqlite3_result_text(ctx, str.c_str(), str.length(), SQLITE_TRANSIENT); +} + +inline void +to_sqlite(sqlite3_context* ctx, const string_fragment& sf) +{ + if (sf.is_valid()) { + sqlite3_result_text( + ctx, &sf.sf_string[sf.sf_begin], sf.length(), SQLITE_TRANSIENT); + } else { + sqlite3_result_null(ctx); + } +} + +inline void +to_sqlite(sqlite3_context* ctx, bool val) +{ + sqlite3_result_int(ctx, val); +} + +template<typename T> +inline void +to_sqlite(sqlite3_context* ctx, + T val, + typename std::enable_if<std::is_integral<T>::value + && !std::is_same<T, bool>::value>::type* dummy + = 0) +{ + sqlite3_result_int64(ctx, val); +} + +inline void +to_sqlite(sqlite3_context* ctx, double val) +{ + sqlite3_result_double(ctx, val); +} + +inline void +to_sqlite(sqlite3_context* ctx, auto_mem<char> str) +{ + auto free_func = str.get_free_func<void(*)(void*)>(); + sqlite3_result_text(ctx, str.release(), -1, free_func); +} + +#define JSON_SUBTYPE 74 /* Ascii for "J" */ +#define FLATTEN_SUBTYPE 0x5f + +template<typename T> +inline void +to_sqlite(sqlite3_context* ctx, nonstd::optional<T>& val) +{ + if (val.has_value()) { + to_sqlite(ctx, val.value()); + } else { + sqlite3_result_null(ctx); + } +} + +template<typename T> +inline void +to_sqlite(sqlite3_context* ctx, nonstd::optional<T> val) +{ + if (val.has_value()) { + to_sqlite(ctx, std::move(val.value())); + } else { + sqlite3_result_null(ctx); + } +} + +struct ToSqliteVisitor { + ToSqliteVisitor(sqlite3_context* vctx) : tsv_context(vctx) {} + + template<typename T> + void operator()(T&& t) const + { + to_sqlite(this->tsv_context, std::move(t)); + } + + sqlite3_context* tsv_context; +}; + +template<typename... Types> +void +to_sqlite(sqlite3_context* ctx, mapbox::util::variant<Types...>&& val) +{ + ToSqliteVisitor visitor(ctx); + + mapbox::util::apply_visitor(visitor, val); +} + +template<typename... Args> +struct optional_counter { + constexpr static int value = 0; +}; + +template<typename T> +struct optional_counter<nonstd::optional<T>> { + constexpr static int value = 1; +}; + +template<typename T, typename U> +struct optional_counter<nonstd::optional<T>, const std::vector<U>&> { + constexpr static int value = 1; +}; + +template<typename T, typename... Rest> +struct optional_counter<nonstd::optional<T>, Rest...> { + constexpr static int value = 1 + sizeof...(Rest); +}; + +template<typename Arg> +struct optional_counter<Arg> { + constexpr static int value = 0; +}; + +template<typename Arg1, typename... Args> +struct optional_counter<Arg1, Args...> : optional_counter<Args...> { +}; + +template<typename... Args> +struct variadic_counter { + constexpr static int value = 0; +}; + +template<typename T> +struct variadic_counter<const std::vector<T>&> { + constexpr static int value = 1; +}; + +template<typename Arg> +struct variadic_counter<Arg> { + constexpr static int value = 0; +}; + +template<typename Arg1, typename... Args> +struct variadic_counter<Arg1, Args...> : variadic_counter<Args...> { +}; + +template<typename F, F f> +struct sqlite_func_adapter; + +template<typename Return, typename... Args, Return (*f)(Args...)> +struct sqlite_func_adapter<Return (*)(Args...), f> { + constexpr static size_t OPT_COUNT = optional_counter<Args...>::value; + constexpr static size_t VAR_COUNT = variadic_counter<Args...>::value; + constexpr static size_t REQ_COUNT = sizeof...(Args) - OPT_COUNT - VAR_COUNT; + + template<size_t... Idx> + static void func2(sqlite3_context* context, + int argc, + sqlite3_value** argv, + std::index_sequence<Idx...>) + { + try { + Return retval = f(from_sqlite<Args>()(argc, argv, Idx)...); + + to_sqlite(context, std::move(retval)); + } catch (const lnav::console::user_message& um) { + to_sqlite(context, um); + } catch (from_sqlite_conversion_error& e) { + char buffer[256]; + + snprintf(buffer, + sizeof(buffer), + "Expecting an %s for argument number %d", + e.e_type, + e.e_argi); + sqlite3_result_error(context, buffer, -1); + } catch (const std::exception& e) { + const auto* fd = (const FuncDef*) sqlite3_user_data(context); + attr_line_t error_al; + error_al.append("call to "); + format_help_text_for_term( + fd->fd_help, 40, error_al, help_text_content::synopsis); + error_al.append(" failed"); + auto um = lnav::console::user_message::error(error_al).with_reason( + e.what()); + + to_sqlite(context, um); + } catch (...) { + sqlite3_result_error( + context, "Function threw an unexpected exception", -1); + } + } + + static void func1(sqlite3_context* context, int argc, sqlite3_value** argv) + { + const static bool IS_NULLABLE[] + = {vtab_types::is_nullable<Args>::value...}; + const static bool IS_SQLITE3_VALUE[] + = {std::is_same<Args, sqlite3_value*>::value...}; + + if ((size_t) argc < REQ_COUNT && VAR_COUNT == 0) { + const struct FuncDef* fd + = (const FuncDef*) sqlite3_user_data(context); + char buffer[128]; + + if (OPT_COUNT == 0) { + snprintf(buffer, + sizeof(buffer), + "%s() expects exactly %ld argument%s", + fd->fd_help.ht_name, + REQ_COUNT, + REQ_COUNT == 1 ? "s" : ""); + } else { + snprintf(buffer, + sizeof(buffer), + "%s() expects between %ld and %ld arguments", + fd->fd_help.ht_name, + REQ_COUNT, + REQ_COUNT + OPT_COUNT); + } + sqlite3_result_error(context, buffer, -1); + return; + } + + for (size_t lpc = 0; lpc < REQ_COUNT; lpc++) { + if (!IS_NULLABLE[lpc] && !IS_SQLITE3_VALUE[lpc] + && sqlite3_value_type(argv[lpc]) == SQLITE_NULL) + { + sqlite3_result_null(context); + return; + } + } + + func2(context, argc, argv, std::make_index_sequence<sizeof...(Args)>{}); + } + + static FuncDef builder(help_text ht) + { + require(ht.ht_parameters.size() == sizeof...(Args)); + + return { + ht.ht_name, + (OPT_COUNT > 0 || VAR_COUNT > 0) ? -1 : (int) REQ_COUNT, + SQLITE_UTF8 | SQLITE_DETERMINISTIC, + 0, + func1, + ht, + }; + } +}; + +extern std::string vtab_module_schemas; +extern std::map<intern_string_t, std::string> vtab_module_ddls; + +class vtab_index_constraints { +public: + vtab_index_constraints(const sqlite3_index_info* index_info) + : vic_index_info(*index_info) + { + } + + struct const_iterator { + const_iterator(vtab_index_constraints* parent, int index = 0) + : i_parent(parent), i_index(index) + { + while (this->i_index < this->i_parent->vic_index_info.nConstraint + && !this->i_parent->vic_index_info.aConstraint[this->i_index] + .usable) + { + this->i_index += 1; + } + } + + const_iterator& operator++() + { + do { + this->i_index += 1; + } while ( + this->i_index < this->i_parent->vic_index_info.nConstraint + && !this->i_parent->vic_index_info.aConstraint[this->i_index] + .usable); + + return *this; + } + + const sqlite3_index_info::sqlite3_index_constraint& operator*() const + { + return this->i_parent->vic_index_info.aConstraint[this->i_index]; + } + + const sqlite3_index_info::sqlite3_index_constraint* operator->() const + { + return &this->i_parent->vic_index_info.aConstraint[this->i_index]; + } + + bool operator!=(const const_iterator& rhs) const + { + return this->i_parent != rhs.i_parent + || this->i_index != rhs.i_index; + } + + const vtab_index_constraints* i_parent; + int i_index; + }; + + const_iterator begin() { return {this}; } + + const_iterator end() { return {this, this->vic_index_info.nConstraint}; } + +private: + const sqlite3_index_info& vic_index_info; +}; + +class vtab_index_usage { +public: + vtab_index_usage(sqlite3_index_info* index_info) + : viu_index_info(*index_info) + { + } + + void column_used(const vtab_index_constraints::const_iterator& iter); + + void allocate_args(int low, int high, int required); + +private: + sqlite3_index_info& viu_index_info; + int viu_used_column_count{0}; + int viu_min_column{INT_MAX}; + int viu_max_column{0}; +}; + +struct vtab_module_base { + virtual int create(sqlite3* db) = 0; + + virtual ~vtab_module_base() = default; +}; + +template<typename T> +struct vtab_module : public vtab_module_base { + struct vtab { + explicit vtab(sqlite3* db, T& impl) : v_db(db), v_impl(impl) {} + + explicit operator sqlite3_vtab*() { return &this->base; } + + sqlite3_vtab v_base{}; + sqlite3* v_db; + T& v_impl; + }; + + static int tvt_create(sqlite3* db, + void* pAux, + int argc, + const char* const* argv, + sqlite3_vtab** pp_vt, + char** pzErr) + { + auto* mod = static_cast<vtab_module<T>*>(pAux); + auto vt = new vtab(db, mod->vm_impl); + + *pp_vt = (sqlite3_vtab*) &vt->v_base; + + return sqlite3_declare_vtab(db, T::CREATE_STMT); + } + + template<typename... Args, size_t... Idx> + static int apply_impl(T& obj, + int (T::*func)(sqlite3_vtab*, + sqlite3_int64&, + Args...), + sqlite3_vtab* tab, + sqlite3_int64& rowid, + sqlite3_value** argv, + std::index_sequence<Idx...>) + { + return (obj.*func)( + tab, rowid, from_sqlite<Args>()(sizeof...(Args), argv, Idx)...); + } + + template<typename... Args> + static int apply(T& obj, + int (T::*func)(sqlite3_vtab*, sqlite3_int64&, Args...), + sqlite3_vtab* tab, + sqlite3_int64& rowid, + int argc, + sqlite3_value** argv) + { + require(sizeof...(Args) == 0 || argc == sizeof...(Args)); + + try { + return apply_impl(obj, + func, + tab, + rowid, + argv, + std::make_index_sequence<sizeof...(Args)>{}); + } catch (const from_sqlite_conversion_error& e) { + tab->zErrMsg = sqlite3_mprintf( + "Expecting an %s for column number %d", e.e_type, e.e_argi); + return SQLITE_ERROR; + } catch (const std::exception& e) { + tab->zErrMsg = sqlite3_mprintf("%s", e.what()); + return SQLITE_ERROR; + } catch (...) { + tab->zErrMsg + = sqlite3_mprintf("Encountered an unexpected exception"); + return SQLITE_ERROR; + } + } + + static int tvt_destructor(sqlite3_vtab* p_svt) + { + vtab* vt = (vtab*) p_svt; + + delete vt; + + return SQLITE_OK; + } + + static int tvt_open(sqlite3_vtab* p_svt, sqlite3_vtab_cursor** pp_cursor) + { + p_svt->zErrMsg = nullptr; + + auto* p_cur = new (typename T::cursor)(p_svt); + + if (p_cur == nullptr) { + return SQLITE_NOMEM; + } else { + *pp_cursor = (sqlite3_vtab_cursor*) p_cur; + } + + return SQLITE_OK; + } + + static int tvt_next(sqlite3_vtab_cursor* cur) + { + auto* p_cur = (typename T::cursor*) cur; + + return p_cur->next(); + } + + static int tvt_eof(sqlite3_vtab_cursor* cur) + { + auto* p_cur = (typename T::cursor*) cur; + + return p_cur->eof(); + } + + static int tvt_close(sqlite3_vtab_cursor* cur) + { + auto* p_cur = (typename T::cursor*) cur; + + delete p_cur; + + return SQLITE_OK; + } + + static int tvt_rowid(sqlite3_vtab_cursor* cur, sqlite_int64* p_rowid) + { + auto* p_cur = (typename T::cursor*) cur; + + return p_cur->get_rowid(*p_rowid); + } + + static int tvt_column(sqlite3_vtab_cursor* cur, + sqlite3_context* ctx, + int col) + { + auto* mod_vt = (typename vtab_module<T>::vtab*) cur->pVtab; + auto* p_cur = (typename T::cursor*) cur; + + return mod_vt->v_impl.get_column(*p_cur, ctx, col); + } + + static int vt_best_index(sqlite3_vtab* tab, sqlite3_index_info* p_info) + { + return SQLITE_OK; + } + + static int vt_filter(sqlite3_vtab_cursor* p_vtc, + int idxNum, + const char* idxStr, + int argc, + sqlite3_value** argv) + { + auto* p_cur = (typename T::cursor*) p_vtc; + + return p_cur->reset(); + } + + static int tvt_update(sqlite3_vtab* tab, + int argc, + sqlite3_value** argv, + sqlite_int64* rowid) + { + auto* mod_vt = (typename vtab_module<T>::vtab*) tab; + + if (argc <= 1) { + sqlite3_int64 rowid = sqlite3_value_int64(argv[0]); + + return mod_vt->v_impl.delete_row(tab, rowid); + } + + if (sqlite3_value_type(argv[0]) == SQLITE_NULL) { + sqlite3_int64* rowid2 = rowid; + return vtab_module<T>::apply(mod_vt->v_impl, + &T::insert_row, + tab, + *rowid2, + argc - 2, + argv + 2); + } + + sqlite3_int64 index = sqlite3_value_int64(argv[0]); + + if (index != sqlite3_value_int64(argv[1])) { + tab->zErrMsg = sqlite3_mprintf( + "The rowids in the lnav_views table cannot be changed"); + return SQLITE_ERROR; + } + + return vtab_module<T>::apply( + mod_vt->v_impl, &T::update_row, tab, index, argc - 2, argv + 2); + } + + template<typename U> + auto addUpdate(U u) -> decltype(&U::delete_row, void()) + { + this->vm_module.xUpdate = tvt_update; + } + + template<typename U> + void addUpdate(...) + { + } + + template<typename... Args> + vtab_module(Args&... args) noexcept : vm_impl(args...) + { + memset(&this->vm_module, 0, sizeof(this->vm_module)); + this->vm_module.iVersion = 0; + this->vm_module.xCreate = tvt_create; + this->vm_module.xConnect = tvt_create; + this->vm_module.xOpen = tvt_open; + this->vm_module.xNext = tvt_next; + this->vm_module.xEof = tvt_eof; + this->vm_module.xClose = tvt_close; + this->vm_module.xDestroy = tvt_destructor; + this->vm_module.xRowid = tvt_rowid; + this->vm_module.xDisconnect = tvt_destructor; + this->vm_module.xBestIndex = vt_best_index; + this->vm_module.xFilter = vt_filter; + this->vm_module.xColumn = tvt_column; + this->addUpdate<T>(this->vm_impl); + } + + ~vtab_module() override = default; + + int create(sqlite3* db, const char* name) + { + auto impl_name = std::string(name); + vtab_module_schemas += T::CREATE_STMT; + vtab_module_ddls[intern_string::lookup(name)] = trim(T::CREATE_STMT); + + // XXX Eponymous tables don't seem to work in older sqlite versions + impl_name += "_impl"; + int rc = sqlite3_create_module( + db, impl_name.c_str(), &this->vm_module, this); + ensure(rc == SQLITE_OK); + auto create_stmt = fmt::format( + FMT_STRING("CREATE VIRTUAL TABLE {} USING {}()"), name, impl_name); + return sqlite3_exec(db, create_stmt.c_str(), nullptr, nullptr, nullptr); + } + + int create(sqlite3* db) override + { + return this->create(db, T::NAME); + } + + sqlite3_module vm_module; + T vm_impl; +}; + +template<typename T> +struct tvt_iterator_cursor { + struct cursor { + sqlite3_vtab_cursor base{}; + + typename T::iterator iter; + + explicit cursor(sqlite3_vtab* vt) + { + auto* mod_vt = (typename vtab_module<T>::vtab*) vt; + + this->base.pVtab = vt; + this->iter = mod_vt->v_impl.begin(); + } + + int reset() + { + this->iter = get_handler().begin(); + + return SQLITE_OK; + } + + int next() + { + if (this->iter != get_handler().end()) { + ++this->iter; + } + + return SQLITE_OK; + } + + int eof() { return this->iter == get_handler().end(); } + + template<bool cond, typename U> + using resolvedType = typename std::enable_if<cond, U>::type; + + template<typename U = int> + resolvedType< + std::is_same<std::random_access_iterator_tag, + typename std::iterator_traits< + typename T::iterator>::iterator_category>::value, + U> + get_rowid(sqlite_int64& rowid_out) + { + rowid_out = std::distance(get_handler().begin(), this->iter); + + return SQLITE_OK; + } + + template<typename U = int> + resolvedType< + !std::is_same<std::random_access_iterator_tag, + typename std::iterator_traits< + typename T::iterator>::iterator_category>::value, + U> + get_rowid(sqlite_int64& rowid_out) + { + rowid_out = get_handler().get_rowid(this->iter); + + return SQLITE_OK; + } + + protected: + T& get_handler() + { + auto* mod_vt = (typename vtab_module<T>::vtab*) this->base.pVtab; + + return mod_vt->v_impl; + } + }; +}; + +template<typename T> +struct tvt_no_update : public T { + using T::T; + + int delete_row(sqlite3_vtab* vt, sqlite3_int64 rowid) + { + vt->zErrMsg = sqlite3_mprintf("Rows cannot be deleted from this table"); + return SQLITE_ERROR; + } + + int insert_row(sqlite3_vtab* tab, sqlite3_int64& rowid_out) + { + tab->zErrMsg + = sqlite3_mprintf("Rows cannot be inserted into this table"); + return SQLITE_ERROR; + } + + int update_row(sqlite3_vtab* tab, sqlite3_int64& rowid_out) + { + tab->zErrMsg = sqlite3_mprintf("Rows cannot be updated in this table"); + return SQLITE_ERROR; + } +}; + +#endif |