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- // Copyright (c) 2012 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #ifndef SQL_STATEMENT_H_
- #define SQL_STATEMENT_H_
- #include <stdint.h>
- #include <string>
- #include <vector>
- #include "base/component_export.h"
- #include "base/containers/span.h"
- #include "base/dcheck_is_on.h"
- #include "base/memory/ref_counted.h"
- #include "base/sequence_checker.h"
- #include "base/strings/string_piece_forward.h"
- #include "base/thread_annotations.h"
- #include "base/time/time.h"
- #include "sql/database.h"
- namespace sql {
- enum class SqliteResultCode : int;
- // Possible return values from ColumnType in a statement. These should match
- // the values in sqlite3.h.
- enum class ColumnType {
- kInteger = 1,
- kFloat = 2,
- kText = 3,
- kBlob = 4,
- kNull = 5,
- };
- // Compiles and executes SQL statements.
- //
- // This class is not thread-safe. An instance must be accessed from a single
- // sequence. This is enforced in DCHECK-enabled builds.
- //
- // Normal usage:
- // sql::Statement s(connection_.GetUniqueStatement(...));
- // s.BindInt(0, a);
- // if (s.Step())
- // return s.ColumnString(0);
- //
- // If there are errors getting the statement, the statement will be inert; no
- // mutating or database-access methods will work. If you need to check for
- // validity, use:
- // if (!s.is_valid())
- // return false;
- //
- // Step() and Run() just return true to signal success. If you want to handle
- // specific errors such as database corruption, install an error handler in
- // in the connection object using set_error_delegate().
- class COMPONENT_EXPORT(SQL) Statement {
- public:
- // Creates an uninitialized statement. The statement will be invalid until
- // you initialize it via Assign.
- Statement();
- explicit Statement(scoped_refptr<Database::StatementRef> ref);
- Statement(const Statement&) = delete;
- Statement& operator=(const Statement&) = delete;
- ~Statement();
- // Initializes this object with the given statement, which may or may not
- // be valid. Use is_valid() to check if it's OK.
- void Assign(scoped_refptr<Database::StatementRef> ref);
- // Resets the statement to an uninitialized state corresponding to
- // the default constructor, releasing the StatementRef.
- void Clear();
- // Returns true if the statement can be executed. All functions can still
- // be used if the statement is invalid, but they will return failure or some
- // default value. This is because the statement can become invalid in the
- // middle of executing a command if there is a serious error and the database
- // has to be reset.
- bool is_valid() const {
- DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
- return ref_->is_valid();
- }
- // Running -------------------------------------------------------------------
- // Executes the statement, returning true on success. This is like Step but
- // for when there is no output, like an INSERT statement.
- bool Run();
- // Executes the statement, returning true if there is a row of data returned.
- // You can keep calling Step() until it returns false to iterate through all
- // the rows in your result set.
- //
- // When Step returns false, the result is either that there is no more data
- // or there is an error. This makes it most convenient for loop usage. If you
- // need to disambiguate these cases, use Succeeded().
- //
- // Typical example:
- // while (s.Step()) {
- // ...
- // }
- // return s.Succeeded();
- bool Step();
- // Resets the statement to its initial condition. This includes any current
- // result row, and also the bound variables if the |clear_bound_vars| is true.
- void Reset(bool clear_bound_vars);
- // Returns true if the last executed thing in this statement succeeded. If
- // there was no last executed thing or the statement is invalid, this will
- // return false.
- bool Succeeded() const;
- // Binding -------------------------------------------------------------------
- // These all take a 0-based parameter index and return true on success.
- // strings there may be out of memory.
- void BindNull(int param_index);
- void BindBool(int param_index, bool val);
- void BindInt(int param_index, int val);
- void BindInt(int param_index,
- int64_t val) = delete; // Call BindInt64() instead.
- void BindInt64(int param_index, int64_t val);
- void BindDouble(int param_index, double val);
- void BindCString(int param_index, const char* val);
- void BindString(int param_index, base::StringPiece val);
- void BindString16(int param_index, base::StringPiece16 value);
- void BindBlob(int param_index, base::span<const uint8_t> value);
- // Overload that makes it easy to pass in std::string values.
- void BindBlob(int param_index, base::span<const char> value) {
- BindBlob(param_index, base::as_bytes(base::make_span(value)));
- }
- // Conforms with base::Time serialization recommendations.
- //
- // This is equivalent to the following snippets, which should be replaced.
- // * BindInt64(col, val.ToInternalValue())
- // * BindInt64(col, val.ToDeltaSinceWindowsEpoch().InMicroseconds())
- //
- // Features that serialize base::Time in other ways, such as ToTimeT() or
- // ToJavaTime(), will require a database migration to be converted to this
- // (recommended) serialization method.
- //
- // TODO(crbug.com/1195962): Migrate all time serialization to this method, and
- // then remove the migration details above.
- void BindTime(int param_index, base::Time time);
- // Retrieving ----------------------------------------------------------------
- // Returns the number of output columns in the result.
- int ColumnCount() const;
- // Returns the type associated with the given column.
- //
- // Watch out: the type may be undefined if you've done something to cause a
- // "type conversion." This means requesting the value of a column of a type
- // where that type is not the native type. For safety, call ColumnType only
- // on a column before getting the value out in any way.
- ColumnType GetColumnType(int col);
- // These all take a 0-based argument index.
- bool ColumnBool(int column_index);
- int ColumnInt(int column_index);
- int64_t ColumnInt64(int column_index);
- double ColumnDouble(int column_index);
- std::string ColumnString(int column_index);
- std::u16string ColumnString16(int column_index);
- // Conforms with base::Time serialization recommendations.
- //
- // This is equivalent to the following snippets, which should be replaced.
- // * base::Time::FromInternalValue(ColumnInt64(col))
- // * base::Time::FromDeltaSinceWindowsEpoch(
- // base::Microseconds(ColumnInt64(col)))
- //
- // TODO(crbug.com/1195962): Migrate all time serialization to this method, and
- // then remove the migration details above.
- base::Time ColumnTime(int column_index);
- // Returns a span pointing to a buffer containing the blob data.
- //
- // The span's contents should be copied to a caller-owned buffer immediately.
- // Any method call on the Statement may invalidate the span.
- //
- // The span will be empty (and may have a null data) if the underlying blob is
- // empty. Code that needs to distinguish between empty blobs and NULL should
- // call GetColumnType() before calling ColumnBlob().
- base::span<const uint8_t> ColumnBlob(int column_index);
- bool ColumnBlobAsString(int column_index, std::string* result);
- bool ColumnBlobAsVector(int column_index, std::vector<char>* result);
- bool ColumnBlobAsVector(int column_index, std::vector<uint8_t>* result);
- // Diagnostics --------------------------------------------------------------
- // Returns the original text of a SQL statement WITHOUT any bound values.
- // Intended for logging in case of failures. Note that DOES NOT return any
- // bound values, because that would cause a privacy / PII issue for logging.
- std::string GetSQLStatement();
- private:
- friend class Database;
- // Checks SQLite result codes and handles any errors.
- //
- // Returns `sqlite_result_code`. This gives callers the convenience of writing
- // "return CheckSqliteResultCode(sqlite_result_code)" and gives the compiler
- // the opportunity of doing tail call optimization (TCO) on the code above.
- //
- // This method reports error codes to the associated Database, and updates
- // internal state to reflect whether the statement succeeded or not.
- SqliteResultCode CheckSqliteResultCode(SqliteResultCode sqlite_result_code);
- // Should be called by all mutating methods to check that the statement is
- // valid. Returns true if the statement is valid. DCHECKS and returns false
- // if it is not.
- // The reason for this is to handle two specific cases in which a Statement
- // may be invalid. The first case is that the programmer made an SQL error.
- // Those cases need to be DCHECKed so that we are guaranteed to find them
- // before release. The second case is that the computer has an error (probably
- // out of disk space) which is prohibiting the correct operation of the
- // database. Our testing apparatus should not exhibit this defect, but release
- // situations may. Therefore, the code is handling disjoint situations in
- // release and test. In test, we're ensuring correct SQL. In release, we're
- // ensuring that contracts are honored in error edge cases.
- bool CheckValid() const;
- // Helper for Run() and Step(), calls sqlite3_step() and returns the checked
- // value from it.
- SqliteResultCode StepInternal();
- // The actual sqlite statement. This may be unique to us, or it may be cached
- // by the Database, which is why it's ref-counted. This pointer is
- // guaranteed non-null.
- scoped_refptr<Database::StatementRef> ref_
- GUARDED_BY_CONTEXT(sequence_checker_);
- // See Succeeded() for what this holds.
- bool succeeded_ GUARDED_BY_CONTEXT(sequence_checker_) = false;
- #if DCHECK_IS_ON()
- // Used to DCHECK() that Bind*() is called before Step() or Run() are called.
- bool step_called_ GUARDED_BY_CONTEXT(sequence_checker_) = false;
- bool run_called_ GUARDED_BY_CONTEXT(sequence_checker_) = false;
- #endif // DCHECK_IS_ON()
- SEQUENCE_CHECKER(sequence_checker_);
- };
- } // namespace sql
- #endif // SQL_STATEMENT_H_
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