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[doc] dart:ffi SQLite sample

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Issue: https://github.com/dart-lang/sdk/issues/35775

Change-Id: I2ce86c554ffd6f49050cf63ead60809c08fb02e5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/97504
Reviewed-by: Michael Thomsen <mit@google.com>
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Daco Harkes 2019-03-26 14:46:09 +00:00 committed by Samir Jindel
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.dart_tool
.gdb_history
.packages
.vscode
pubspec.lock
test.db
test.db-journal

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# Sample code dart:ffi
This is an illustrative sample for how to use `dart:ffi`.
## Building and Running this Sample
Building and running this sample is done through pub.
Running `pub get` and `pub run test` should produce the following output.
```sh
$ pub get
Resolving dependencies... (6.8s)
+ analyzer 0.35.4
...
+ yaml 2.1.15
Downloading analyzer 0.35.4...
Downloading kernel 0.3.14...
Downloading front_end 0.1.14...
Changed 47 dependencies!
Precompiling executables... (18.0s)
Precompiled test:test.
```
```
$ pub run test
00:01 +0: test/sqlite_test.dart: sqlite integration test
1 Chocolade chip cookie Chocolade cookie foo
2 Ginger cookie null 42
3 Cinnamon roll null null
1 Chocolade chip cookie Chocolade cookie foo
2 Ginger cookie null 42
expected exception on accessing result data after close: The result has already been closed.
expected this query to fail: no such column: non_existing_column (Code 1: SQL logic error)
00:02 +3: All tests passed!
```
## Tutorial
A tutorial walking through the code is available in [docs/sqlite-tutorial.md](docs/sqlite-tutorial.md).

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# dart:ffi SQLite mini tutorial
In this mini tutorial we learn how to bind SQLite, a native library, in Dart using Dart's new foreign function interface `dart:ffi`.
We build a package which provides a Dartlike SQLite API using objects and `Iterator`s.
Inside the package we write Dart code which directly invokes C functions and manipulates C memory.
## Binding C Functions to Dart
The first step is to load a Native Library:
```dart
import "dart:ffi";
DynamicLibrary sqlite = dlopenPlatformSpecific("sqlite3");
```
In a `DynamicLibrary` we can `lookup` functions.
Let's lookup the function `sqlite3_prepare_v2` in the SQLite library.
That function has the following signature in the library header file.
```c++
SQLITE_API int sqlite3_prepare_v2(
sqlite3 *db, /* Database handle */
const char *zSql, /* SQL statement, UTF-8 encoded */
int nByte, /* Maximum length of zSql in bytes. */
sqlite3_stmt **ppStmt, /* OUT: Statement handle */
const char **pzTail /* OUT: Pointer to unused portion of zSql */
);
```
In order to lookup a function, we need a _C signature_ and a _Dart signature_.
```dart
typedef sqlite3_prepare_v2_native_t = Int32 Function(
DatabasePointer database,
CString query,
Int32 nbytes,
Pointer<StatementPointer> statementOut,
Pointer<CString> tail);
typedef Sqlite3_prepare_v2_t = int Function(
DatabasePointer database,
CString query,
int nbytes,
Pointer<StatementPointer> statementOut,
Pointer<CString> tail);
```
With these two signatures we can `lookup` the C function and expose it as a Dart function with `asFunction`.
```dart
Sqlite3_prepare_v2_t sqlite3_prepare_v2 = sqlite
.lookup<NativeFunction<sqlite3_prepare_v2_native_t>>("sqlite3_prepare_v2")
.asFunction();
```
Browse the code: [platform specific dynamic library loading](../lib/src/ffi/dylib_utils.dart), [C signatures](../lib/src/bindings/signatures.dart), [Dart signatures and bindings](../lib/src/bindings/bindings.dart), and [dart:ffi dynamic library interface](../../../../sdk/lib/ffi/dynamic_library.dart).
## Managing C Memory
In order to call `sqlite3_prepare_v2` to prepare a SQLite statement before executing, we need to be able to pass C pointers to C functions.
Database and Statement pointers are opaque pointers in the SQLite C API.
We specify these as classes extending `Pointer<Void>`.
```dart
class DatabasePointer extends Pointer<Void> {}
class StatementPointer extends Pointer<Void> {}
```
Strings in C are pointers to character arrays.
```dart
class CString extends Pointer<Int8> {}
```
Pointers to C integers, floats, an doubles can be read from and written through to `dart:ffi`.
However, before we can write to C memory from dart, we need to `allocate` some memory.
```dart
Pointer<Int8> p = allocate(); // Infers type argument allocate<Int8>(), and allocates 1 byte.
p.store(123); // Stores a Dart int into this C int8.
int v = p.load(); // Infers type argument p.load<int>(), and loads a value from C memory.
```
Note that you can only load a Dart `int` from a C `Int8`.
Trying to load a Dart `double` will result in a runtime exception.
We've almost modeled C Strings.
The last thing we need is to use this `Pointer` as an array.
We can do this by using `elementAt`.
```dart
CString string = allocate(count: 4).cast(); // Allocates 4 bytes and casts it to a string.
string.store(73); // Stores 'F' at index 0.
string.elementAt(1).store(73); // Stores 'F' at index 1.
string.elementAt(2).store(70); // Stores 'I' at index 2.
string.elementAt(3).store(0); // Null terminates the string.
```
We wrap the above logic of allocating strings in the constructor `CString.allocate`.
Now we have all ingredients to call `sqlite3_prepare_v2`.
```dart
Pointer<StatementPointer> statementOut = allocate();
CString queryC = CString.allocate(query);
int resultCode = sqlite3_prepare_v2(
_database, queryC, -1, statementOut, fromAddress(0));
```
With `dart:ffi` we are responsible for freeing C memory that we allocate.
So after calling `sqlite3_prepare_v2` we read out the statement pointer, and free the statement pointer pointer and `CString` which held the query string.
```
StatementPointer statement = statementOut.load();
statementOut.free();
queryC.free();
```
Browse the code: [CString class](../lib/src/ffi/cstring.dart), [code calling sqlite3_prepare_v2](../lib/src/database.dart#57), and [dart:ffi pointer interface](../../../../sdk/lib/ffi/ffi.dart).
## Dart API
We would like to present the users of our package with an object oriented API - not exposing any `dart:ffi` objects to them.
The SQLite C API returns a cursor to the first row of a result after executing a query.
We can read out the columns of this row and move the cursor to the next row.
The most natural way to expose this in Dart is through an `Iterable`.
We provide our package users with the following API.
```dart
class Result implements Iterable<Row> {}
class Row {
dynamic readColumnByIndex(int columnIndex) {}
dynamic readColumn(String columnName) {}
}
```
However, this interface does not completely match the semantics of the C API.
When we start reading the next `Row`, we do no longer have access to the previous `Row`.
We can model this by letting a `Row` keep track if its current or not.
```dart
class Row {
bool _isCurrentRow = true;
dynamic readColumnByIndex(int columnIndex) {
if (!_isCurrentRow) {
throw Exception(
"This row is not the current row, reading data from the non-current"
" row is not supported by sqlite.");
}
// ...
}
}
```
A second mismatch between Dart and C is that in C we have to manually release resources.
After executing a query and reading its results we need to call `sqlite3_finalize(statement)`.
We can take two approaches here, either we structure the API in such a way that users of our package (implicitly) release resources, or we use finalizers to release resources.
In this tutorial we take the first approach.
If our users iterate over all `Row`s, we can implicitly finalize the statement after they are done with the last row.
However, if they decide they do not want to iterate over the whole result, they need to explicitly state this.
In this tutorial, we use the `ClosableIterator` abstraction for `Iterators` with backing resources that need to be `close`d.
```dart
Result result = d.query("""
select id, name
from Cookies
;""");
for (Row r in result) {
String name = r.readColumn("name");
print(name);
}
// Implicitly closes the iterator.
result = d.query("""
select id, name
from Cookies
;""");
for (Row r in result) {
int id = r.readColumn("id");
if (id == 1) {
result.close(); // Explicitly closes the iterator, releasing underlying resources.
break;
}
}
```
Browse the code: [Database, Result, Row](../lib/src/database.dart), and [CloseableIterator](../lib/src/collections/closable_iterator.dart).
## Architecture Overview
The following diagram summarized what we have implemented as _package developers_ in this tutorial.
![architecture](lib/scenario-default.svg)
As the package developers wrapping an existing native library, we have only written Dart code - not any C/C++ code.
We specified bindings to the native library.
We have provided our package users with an object oriented API without exposing any `dart:ffi` objects.
And finally, we have implemented the package API by calling the C API.
## Current dart:ffi Development Status
In this minitutorial we used these `dart:ffi` features:
* Loading dynamic libararies and looking up C functions in these dynamic libraries.
* Calling C functions, with `dart:ffi` automatically marshalling arguments and return value.
* Manipulating C memory through `Pointer`s with `allocate`, `free`, `load`, `store`, and `elementAt`.
Features which we did not use in this tutorial:
* `@struct` on subtypes of `Pointer` to define a struct with fields. (However, this feature is likely to change in the future.)
Features which `dart:ffi` does not support yet:
* Callbacks from C back into Dart.
* Finalizers
* C++ Exceptions (Not on roadmap yet.)
Platform limitations:
* `dart:ffi` is only enabled on 64 bit Windows, Linux, and MacOS. (Arm64 and 32 bit Intel are under review.)
* `dart:ffi` only works in JIT mode, not in AOT.
It is possible to work around some of the current limitations by adding a C/C++ layer.
For example we could catch C++ exceptions in a C++ layer, and rethrow them in Dart.
The architecture diagram would change to the following in that case.
![architecture2](lib/scenario-full.svg)

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/// A synchronous SQLite wrapper.
///
/// Written using dart:ffi.
library sqlite;
export "src/database.dart";

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import "dart:ffi";
import "../ffi/cstring.dart";
import "../ffi/dylib_utils.dart";
import "signatures.dart";
import "types.dart";
class _SQLiteBindings {
DynamicLibrary sqlite;
/// Opening A New Database Connection
///
/// ^These routines open an SQLite database file as specified by the
/// filename argument. ^The filename argument is interpreted as UTF-8 for
/// sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte
/// order for sqlite3_open16(). ^(A database connection handle is usually
/// returned in *ppDb, even if an error occurs. The only exception is that
/// if SQLite is unable to allocate memory to hold the sqlite3 object,
/// a NULL will be written into *ppDb instead of a pointer to the sqlite3
/// object.)^ ^(If the database is opened (and/or created) successfully, then
/// [SQLITE_OK] is returned. Otherwise an error code is returned.)^ ^The
/// [sqlite3_errmsg] or sqlite3_errmsg16() routines can be used to obtain
/// an English language description of the error following a failure of any
/// of the sqlite3_open() routines.
int Function(CString filename, Pointer<DatabasePointer> databaseOut,
int flags, CString vfs) sqlite3_open_v2;
int Function(DatabasePointer database) sqlite3_close_v2;
/// Compiling An SQL Statement
///
/// To execute an SQL query, it must first be compiled into a byte-code
/// program using one of these routines.
///
/// The first argument, "db", is a database connection obtained from a
/// prior successful call to sqlite3_open, [sqlite3_open_v2] or
/// sqlite3_open16. The database connection must not have been closed.
///
/// The second argument, "zSql", is the statement to be compiled, encoded
/// as either UTF-8 or UTF-16. The sqlite3_prepare() and sqlite3_prepare_v2()
/// interfaces use UTF-8, and sqlite3_prepare16() and sqlite3_prepare16_v2()
/// use UTF-16.
///
/// ^If the nByte argument is less than zero, then zSql is read up to the
/// first zero terminator. ^If nByte is non-negative, then it is the maximum
/// number of bytes read from zSql. ^When nByte is non-negative, the
/// zSql string ends at either the first '\000' or '\u0000' character or
/// the nByte-th byte, whichever comes first. If the caller knows
/// that the supplied string is nul-terminated, then there is a small
/// performance advantage to be gained by passing an nByte parameter that
/// is equal to the number of bytes in the input string <i>including</i>
/// the nul-terminator bytes.
///
/// ^If pzTail is not NULL then *pzTail is made to point to the first byte
/// past the end of the first SQL statement in zSql. These routines only
/// compile the first statement in zSql, so *pzTail is left pointing to
/// what remains uncompiled.
///
/// ^*ppStmt is left pointing to a compiled prepared statement that can be
/// executed using sqlite3_step. ^If there is an error, *ppStmt is set
/// to NULL. ^If the input text contains no SQL (if the input is an empty
/// string or a comment) then *ppStmt is set to NULL.
/// The calling procedure is responsible for deleting the compiled
/// SQL statement using [sqlite3_finalize] after it has finished with it.
/// ppStmt may not be NULL.
///
/// ^On success, the sqlite3_prepare family of routines return [SQLITE_OK];
/// otherwise an error code is returned.
///
/// The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are
/// recommended for all new programs. The two older interfaces are retained
/// for backwards compatibility, but their use is discouraged.
/// ^In the "v2" interfaces, the prepared statement
/// that is returned (the sqlite3_stmt object) contains a copy of the
/// original SQL text. This causes the [sqlite3_step] interface to
/// behave differently in three ways:
int Function(
DatabasePointer database,
CString query,
int nbytes,
Pointer<StatementPointer> statementOut,
Pointer<CString> tail) sqlite3_prepare_v2;
/// Evaluate An SQL Statement
///
/// After a prepared statement has been prepared using either
/// [sqlite3_prepare_v2] or sqlite3_prepare16_v2() or one of the legacy
/// interfaces sqlite3_prepare() or sqlite3_prepare16(), this function
/// must be called one or more times to evaluate the statement.
///
/// The details of the behavior of the sqlite3_step() interface depend
/// on whether the statement was prepared using the newer "v2" interface
/// [sqlite3_prepare_v2] and sqlite3_prepare16_v2() or the older legacy
/// interface sqlite3_prepare() and sqlite3_prepare16(). The use of the
/// new "v2" interface is recommended for new applications but the legacy
/// interface will continue to be supported.
///
/// ^In the legacy interface, the return value will be either [SQLITE_BUSY],
/// [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
/// ^With the "v2" interface, any of the other [result codes] or
/// [extended result codes] might be returned as well.
///
/// ^[SQLITE_BUSY] means that the database engine was unable to acquire the
/// database locks it needs to do its job. ^If the statement is a [COMMIT]
/// or occurs outside of an explicit transaction, then you can retry the
/// statement. If the statement is not a [COMMIT] and occurs within an
/// explicit transaction then you should rollback the transaction before
/// continuing.
///
/// ^[SQLITE_DONE] means that the statement has finished executing
/// successfully. sqlite3_step() should not be called again on this virtual
/// machine without first calling [sqlite3_reset()] to reset the virtual
/// machine back to its initial state.
///
/// ^If the SQL statement being executed returns any data, then [SQLITE_ROW]
/// is returned each time a new row of data is ready for processing by the
/// caller. The values may be accessed using the [column access functions].
/// sqlite3_step() is called again to retrieve the next row of data.
///
/// ^[SQLITE_ERROR] means that a run-time error (such as a constraint
/// violation) has occurred. sqlite3_step() should not be called again on
/// the VM. More information may be found by calling [sqlite3_errmsg()].
/// ^With the legacy interface, a more specific error code (for example,
/// [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth)
/// can be obtained by calling [sqlite3_reset()] on the
/// prepared statement. ^In the "v2" interface,
/// the more specific error code is returned directly by sqlite3_step().
///
/// [SQLITE_MISUSE] means that the this routine was called inappropriately.
/// Perhaps it was called on a prepared statement that has
/// already been [sqlite3_finalize | finalized] or on one that had
/// previously returned [SQLITE_ERROR] or [SQLITE_DONE]. Or it could
/// be the case that the same database connection is being used by two or
/// more threads at the same moment in time.
///
/// For all versions of SQLite up to and including 3.6.23.1, a call to
/// [sqlite3_reset] was required after sqlite3_step() returned anything
/// other than [Errors.SQLITE_ROW] before any subsequent invocation of
/// sqlite3_step(). Failure to reset the prepared statement using
/// [sqlite3_reset()] would result in an [Errors.SQLITE_MISUSE] return from
/// sqlite3_step(). But after version 3.6.23.1, sqlite3_step() began
/// calling [sqlite3_reset] automatically in this circumstance rather
/// than returning [Errors.SQLITE_MISUSE]. This is not considered a
/// compatibility break because any application that ever receives an
/// [Errors.SQLITE_MISUSE] error is broken by definition. The
/// [SQLITE_OMIT_AUTORESET] compile-time option
/// can be used to restore the legacy behavior.
///
/// <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
/// API always returns a generic error code, [SQLITE_ERROR], following any
/// error other than [SQLITE_BUSY] and [SQLITE_MISUSE]. You must call
/// [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
/// specific [error codes] that better describes the error.
/// We admit that this is a goofy design. The problem has been fixed
/// with the "v2" interface. If you prepare all of your SQL statements
/// using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] instead
/// of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces,
/// then the more specific [error codes] are returned directly
/// by sqlite3_step(). The use of the "v2" interface is recommended.
int Function(StatementPointer statement) sqlite3_step;
/// CAPI3REF: Reset A Prepared Statement Object
///
/// The sqlite3_reset() function is called to reset a prepared statement
/// object back to its initial state, ready to be re-executed.
/// ^Any SQL statement variables that had values bound to them using
/// the sqlite3_bind_blob | sqlite3_bind_*() API retain their values.
/// Use sqlite3_clear_bindings() to reset the bindings.
///
/// ^The [sqlite3_reset] interface resets the prepared statement S
/// back to the beginning of its program.
///
/// ^If the most recent call to [sqlite3_step] for the
/// prepared statement S returned [Errors.SQLITE_ROW] or [Errors.SQLITE_DONE],
/// or if [sqlite3_step] has never before been called on S,
/// then [sqlite3_reset] returns [Errors.SQLITE_OK].
///
/// ^If the most recent call to [sqlite3_step(S)] for the
/// prepared statement S indicated an error, then
/// [sqlite3_reset] returns an appropriate [Errors].
///
/// ^The [sqlite3_reset] interface does not change the values
int Function(StatementPointer statement) sqlite3_reset;
/// Destroy A Prepared Statement Object
///
/// ^The sqlite3_finalize() function is called to delete a prepared statement.
/// ^If the most recent evaluation of the statement encountered no errors
/// or if the statement is never been evaluated, then sqlite3_finalize()
/// returns SQLITE_OK. ^If the most recent evaluation of statement S failed,
/// then sqlite3_finalize(S) returns the appropriate error code or extended
/// error code.
///
/// ^The sqlite3_finalize(S) routine can be called at any point during
/// the life cycle of prepared statement S:
/// before statement S is ever evaluated, after
/// one or more calls to [sqlite3_reset], or after any call
/// to [sqlite3_step] regardless of whether or not the statement has
/// completed execution.
///
/// ^Invoking sqlite3_finalize() on a NULL pointer is a harmless no-op.
///
/// The application must finalize every prepared statement in order to avoid
/// resource leaks. It is a grievous error for the application to try to use
/// a prepared statement after it has been finalized. Any use of a prepared
/// statement after it has been finalized can result in undefined and
/// undesirable behavior such as segfaults and heap corruption.
int Function(StatementPointer statement) sqlite3_finalize;
/// Number Of Columns In A Result Set
///
/// ^Return the number of columns in the result set returned by the
/// prepared statement. ^This routine returns 0 if pStmt is an SQL
/// statement that does not return data (for example an [UPDATE]).
int Function(StatementPointer statement) sqlite3_column_count;
/// Column Names In A Result Set
///
/// ^These routines return the name assigned to a particular column
/// in the result set of a SELECT statement. ^The sqlite3_column_name()
/// interface returns a pointer to a zero-terminated UTF-8 string
/// and sqlite3_column_name16() returns a pointer to a zero-terminated
/// UTF-16 string. ^The first parameter is the prepared statement
/// that implements the SELECT statement. ^The second parameter is the
/// column number. ^The leftmost column is number 0.
///
/// ^The returned string pointer is valid until either the prepared statement
/// is destroyed by [sqlite3_finalize] or until the statement is automatically
/// reprepared by the first call to [sqlite3_step] for a particular run
/// or until the next call to
/// sqlite3_column_name() or sqlite3_column_name16() on the same column.
///
/// ^If sqlite3_malloc() fails during the processing of either routine
/// (for example during a conversion from UTF-8 to UTF-16) then a
/// NULL pointer is returned.
///
/// ^The name of a result column is the value of the "AS" clause for
/// that column, if there is an AS clause. If there is no AS clause
/// then the name of the column is unspecified and may change from
CString Function(StatementPointer statement, int columnIndex)
sqlite3_column_name;
/// CAPI3REF: Declared Datatype Of A Query Result
///
/// ^(The first parameter is a prepared statement.
/// If this statement is a SELECT statement and the Nth column of the
/// returned result set of that SELECT is a table column (not an
/// expression or subquery) then the declared type of the table
/// column is returned.)^ ^If the Nth column of the result set is an
/// expression or subquery, then a NULL pointer is returned.
/// ^The returned string is always UTF-8 encoded.
///
/// ^(For example, given the database schema:
///
/// CREATE TABLE t1(c1 VARIANT);
///
/// and the following statement to be compiled:
///
/// SELECT c1 + 1, c1 FROM t1;
///
/// this routine would return the string "VARIANT" for the second result
/// column (i==1), and a NULL pointer for the first result column (i==0).)^
///
/// ^SQLite uses dynamic run-time typing. ^So just because a column
/// is declared to contain a particular type does not mean that the
/// data stored in that column is of the declared type. SQLite is
/// strongly typed, but the typing is dynamic not static. ^Type
/// is associated with individual values, not with the containers
/// used to hold those values.
CString Function(StatementPointer statement, int columnIndex)
sqlite3_column_decltype;
int Function(StatementPointer statement, int columnIndex) sqlite3_column_type;
ValuePointer Function(StatementPointer statement, int columnIndex)
sqlite3_column_value;
double Function(StatementPointer statement, int columnIndex)
sqlite3_column_double;
int Function(StatementPointer statement, int columnIndex) sqlite3_column_int;
CString Function(StatementPointer statement, int columnIndex)
sqlite3_column_text;
/// The sqlite3_errstr() interface returns the English-language text that
/// describes the result code, as UTF-8. Memory to hold the error message
/// string is managed internally and must not be freed by the application.
CString Function(int code) sqlite3_errstr;
/// Error Codes And Messages
///
/// ^The sqlite3_errcode() interface returns the numeric [result code] or
/// [extended result code] for the most recent failed sqlite3_* API call
/// associated with a [database connection]. If a prior API call failed
/// but the most recent API call succeeded, the return value from
/// sqlite3_errcode() is undefined. ^The sqlite3_extended_errcode()
/// interface is the same except that it always returns the
/// [extended result code] even when extended result codes are
/// disabled.
///
/// ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
/// text that describes the error, as either UTF-8 or UTF-16 respectively.
/// ^(Memory to hold the error message string is managed internally.
/// The application does not need to worry about freeing the result.
/// However, the error string might be overwritten or deallocated by
/// subsequent calls to other SQLite interface functions.)^
///
/// When the serialized [threading mode] is in use, it might be the
/// case that a second error occurs on a separate thread in between
/// the time of the first error and the call to these interfaces.
/// When that happens, the second error will be reported since these
/// interfaces always report the most recent result. To avoid
/// this, each thread can obtain exclusive use of the [database connection] D
/// by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning
/// to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after
/// all calls to the interfaces listed here are completed.
///
/// If an interface fails with SQLITE_MISUSE, that means the interface
/// was invoked incorrectly by the application. In that case, the
/// error code and message may or may not be set.
CString Function(DatabasePointer database) sqlite3_errmsg;
_SQLiteBindings() {
sqlite = dlopenPlatformSpecific("sqlite3");
sqlite3_open_v2 = sqlite
.lookup<NativeFunction<sqlite3_open_v2_native_t>>("sqlite3_open_v2")
.asFunction();
sqlite3_close_v2 = sqlite
.lookup<NativeFunction<sqlite3_close_v2_native_t>>("sqlite3_close_v2")
.asFunction();
sqlite3_prepare_v2 = sqlite
.lookup<NativeFunction<sqlite3_prepare_v2_native_t>>(
"sqlite3_prepare_v2")
.asFunction();
sqlite3_step = sqlite
.lookup<NativeFunction<sqlite3_step_native_t>>("sqlite3_step")
.asFunction();
sqlite3_reset = sqlite
.lookup<NativeFunction<sqlite3_reset_native_t>>("sqlite3_reset")
.asFunction();
sqlite3_finalize = sqlite
.lookup<NativeFunction<sqlite3_finalize_native_t>>("sqlite3_finalize")
.asFunction();
sqlite3_errstr = sqlite
.lookup<NativeFunction<sqlite3_errstr_native_t>>("sqlite3_errstr")
.asFunction();
sqlite3_errmsg = sqlite
.lookup<NativeFunction<sqlite3_errmsg_native_t>>("sqlite3_errmsg")
.asFunction();
sqlite3_column_count = sqlite
.lookup<NativeFunction<sqlite3_column_count_native_t>>(
"sqlite3_column_count")
.asFunction();
sqlite3_column_name = sqlite
.lookup<NativeFunction<sqlite3_column_name_native_t>>(
"sqlite3_column_name")
.asFunction();
sqlite3_column_decltype = sqlite
.lookup<NativeFunction<sqlite3_column_decltype_native_t>>(
"sqlite3_column_decltype")
.asFunction();
sqlite3_column_type = sqlite
.lookup<NativeFunction<sqlite3_column_type_native_t>>(
"sqlite3_column_type")
.asFunction();
sqlite3_column_value = sqlite
.lookup<NativeFunction<sqlite3_column_value_native_t>>(
"sqlite3_column_value")
.asFunction();
sqlite3_column_double = sqlite
.lookup<NativeFunction<sqlite3_column_double_native_t>>(
"sqlite3_column_double")
.asFunction();
sqlite3_column_int = sqlite
.lookup<NativeFunction<sqlite3_column_int_native_t>>(
"sqlite3_column_int")
.asFunction();
sqlite3_column_text = sqlite
.lookup<NativeFunction<sqlite3_column_text_native_t>>(
"sqlite3_column_text")
.asFunction();
}
}
_SQLiteBindings _cachedBindings;
_SQLiteBindings get bindings => _cachedBindings ??= _SQLiteBindings();

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/// Result Codes
///
/// Many SQLite functions return an integer result code from the set shown
/// here in order to indicates success or failure.
///
/// New error codes may be added in future versions of SQLite.
///
/// See also: SQLITE_IOERR_READ | extended result codes,
/// sqlite3_vtab_on_conflict() SQLITE_ROLLBACK | result codes.
class Errors {
/// Successful result
static const int SQLITE_OK = 0;
/// Generic error
static const int SQLITE_ERROR = 1;
/// Internal logic error in SQLite
static const int SQLITE_INTERNAL = 2;
/// Access permission denied
static const int SQLITE_PERM = 3;
/// Callback routine requested an abort
static const int SQLITE_ABORT = 4;
/// The database file is locked
static const int SQLITE_BUSY = 5;
/// A table in the database is locked
static const int SQLITE_LOCKED = 6;
/// A malloc() failed
static const int SQLITE_NOMEM = 7;
/// Attempt to write a readonly database
static const int SQLITE_READONLY = 8;
/// Operation terminated by sqlite3_interrupt()
static const int SQLITE_INTERRUPT = 9;
/// Some kind of disk I/O error occurred
static const int SQLITE_IOERR = 10;
/// The database disk image is malformed
static const int SQLITE_CORRUPT = 11;
/// Unknown opcode in sqlite3_file_control()
static const int SQLITE_NOTFOUND = 12;
/// Insertion failed because database is full
static const int SQLITE_FULL = 13;
/// Unable to open the database file
static const int SQLITE_CANTOPEN = 14;
/// Database lock protocol error
static const int SQLITE_PROTOCOL = 15;
/// Internal use only
static const int SQLITE_EMPTY = 16;
/// The database schema changed
static const int SQLITE_SCHEMA = 17;
/// String or BLOB exceeds size limit
static const int SQLITE_TOOBIG = 18;
/// Abort due to constraint violation
static const int SQLITE_CONSTRAINT = 19;
/// Data type mismatch
static const int SQLITE_MISMATCH = 20;
/// Library used incorrectly
static const int SQLITE_MISUSE = 21;
/// Uses OS features not supported on host
static const int SQLITE_NOLFS = 22;
/// Authorization denied
static const int SQLITE_AUTH = 23;
/// Not used
static const int SQLITE_FORMAT = 24;
/// 2nd parameter to sqlite3_bind out of range
static const int SQLITE_RANGE = 25;
/// File opened that is not a database file
static const int SQLITE_NOTADB = 26;
/// Notifications from sqlite3_log()
static const int SQLITE_NOTICE = 27;
/// Warnings from sqlite3_log()
static const int SQLITE_WARNING = 28;
/// sqlite3_step() has another row ready
static const int SQLITE_ROW = 100;
/// sqlite3_step() has finished executing
static const int SQLITE_DONE = 101;
}
/// Flags For File Open Operations
///
/// These bit values are intended for use in the
/// 3rd parameter to the [sqlite3_open_v2()] interface and
/// in the 4th parameter to the [sqlite3_vfs.xOpen] method.
class Flags {
/// Ok for sqlite3_open_v2()
static const int SQLITE_OPEN_READONLY = 0x00000001;
/// Ok for sqlite3_open_v2()
static const int SQLITE_OPEN_READWRITE = 0x00000002;
/// Ok for sqlite3_open_v2()
static const int SQLITE_OPEN_CREATE = 0x00000004;
/// VFS only
static const int SQLITE_OPEN_DELETEONCLOSE = 0x00000008;
/// VFS only
static const int SQLITE_OPEN_EXCLUSIVE = 0x00000010;
/// VFS only
static const int SQLITE_OPEN_AUTOPROXY = 0x00000020;
/// Ok for sqlite3_open_v2()
static const int SQLITE_OPEN_URI = 0x00000040;
/// Ok for sqlite3_open_v2()
static const int SQLITE_OPEN_MEMORY = 0x00000080;
/// VFS only
static const int SQLITE_OPEN_MAIN_DB = 0x00000100;
/// VFS only
static const int SQLITE_OPEN_TEMP_DB = 0x00000200;
/// VFS only
static const int SQLITE_OPEN_TRANSIENT_DB = 0x00000400;
/// VFS only
static const int SQLITE_OPEN_MAIN_JOURNAL = 0x00000800;
/// VFS only
static const int SQLITE_OPEN_TEMP_JOURNAL = 0x00001000;
/// VFS only
static const int SQLITE_OPEN_SUBJOURNAL = 0x00002000;
/// VFS only
static const int SQLITE_OPEN_MASTER_JOURNAL = 0x00004000;
/// Ok for sqlite3_open_v2()
static const int SQLITE_OPEN_NOMUTEX = 0x00008000;
/// Ok for sqlite3_open_v2()
static const int SQLITE_OPEN_FULLMUTEX = 0x00010000;
/// Ok for sqlite3_open_v2()
static const int SQLITE_OPEN_SHAREDCACHE = 0x00020000;
/// Ok for sqlite3_open_v2()
static const int SQLITE_OPEN_PRIVATECACHE = 0x00040000;
/// VFS only
static const int SQLITE_OPEN_WAL = 0x00080000;
}
class Types {
static const int SQLITE_INTEGER = 1;
static const int SQLITE_FLOAT = 2;
static const int SQLITE_TEXT = 3;
static const int SQLITE_BLOB = 4;
static const int SQLITE_NULL = 5;
}

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import "dart:ffi";
import "../ffi/cstring.dart";
import "types.dart";
typedef sqlite3_open_v2_native_t = Int32 Function(
CString filename, Pointer<DatabasePointer> ppDb, Int32 flags, CString vfs);
typedef sqlite3_close_v2_native_t = Int32 Function(DatabasePointer database);
typedef sqlite3_prepare_v2_native_t = Int32 Function(
DatabasePointer database,
CString query,
Int32 nbytes,
Pointer<StatementPointer> statementOut,
Pointer<CString> tail);
typedef sqlite3_step_native_t = Int32 Function(StatementPointer statement);
typedef sqlite3_reset_native_t = Int32 Function(StatementPointer statement);
typedef sqlite3_finalize_native_t = Int32 Function(StatementPointer statement);
typedef sqlite3_errstr_native_t = CString Function(Int32 error);
typedef sqlite3_errmsg_native_t = CString Function(DatabasePointer database);
typedef sqlite3_column_count_native_t = Int32 Function(
StatementPointer statement);
typedef sqlite3_column_name_native_t = CString Function(
StatementPointer statement, Int32 columnIndex);
typedef sqlite3_column_decltype_native_t = CString Function(
StatementPointer statement, Int32 columnIndex);
typedef sqlite3_column_type_native_t = Int32 Function(
StatementPointer statement, Int32 columnIndex);
typedef sqlite3_column_value_native_t = ValuePointer Function(
StatementPointer statement, Int32 columnIndex);
typedef sqlite3_column_double_native_t = Double Function(
StatementPointer statement, Int32 columnIndex);
typedef sqlite3_column_int_native_t = Int32 Function(
StatementPointer statement, Int32 columnIndex);
typedef sqlite3_column_text_native_t = CString Function(
StatementPointer statement, Int32 columnIndex);

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import "dart:ffi";
import "../ffi/cstring.dart";
/// Database Connection Handle
///
/// Each open SQLite database is represented by a pointer to an instance of
/// the opaque structure named "sqlite3". It is useful to think of an sqlite3
/// pointer as an object. The [sqlite3_open()], [sqlite3_open16()], and
/// [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]
/// is its destructor. There are many other interfaces (such as
/// [sqlite3_prepare_v2()], [sqlite3_create_function()], and
/// [sqlite3_busy_timeout()] to name but three) that are methods on an
class DatabasePointer extends Pointer<Void> {}
/// SQL Statement Object
///
/// An instance of this object represents a single SQL statement.
/// This object is variously known as a "prepared statement" or a
/// "compiled SQL statement" or simply as a "statement".
///
/// The life of a statement object goes something like this:
///
/// <ol>
/// <li> Create the object using [sqlite3_prepare_v2()] or a related
/// function.
/// <li> Bind values to [host parameters] using the sqlite3_bind_*()
/// interfaces.
/// <li> Run the SQL by calling [sqlite3_step()] one or more times.
/// <li> Reset the statement using [sqlite3_reset()] then go back
/// to step 2. Do this zero or more times.
/// <li> Destroy the object using [sqlite3_finalize()].
/// </ol>
///
/// Refer to documentation on individual methods above for additional
/// information.
class StatementPointer extends Pointer<Void> {}
/// Dynamically Typed Value Object
///
/// SQLite uses the sqlite3_value object to represent all values
/// that can be stored in a database table. SQLite uses dynamic typing
/// for the values it stores. ^Values stored in sqlite3_value objects
/// can be integers, floating point values, strings, BLOBs, or NULL.
///
/// An sqlite3_value object may be either "protected" or "unprotected".
/// Some interfaces require a protected sqlite3_value. Other interfaces
/// will accept either a protected or an unprotected sqlite3_value.
/// Every interface that accepts sqlite3_value arguments specifies
/// whether or not it requires a protected sqlite3_value.
///
/// The terms "protected" and "unprotected" refer to whether or not
/// a mutex is held. An internal mutex is held for a protected
/// sqlite3_value object but no mutex is held for an unprotected
/// sqlite3_value object. If SQLite is compiled to be single-threaded
/// (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
/// or if SQLite is run in one of reduced mutex modes
/// [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]
/// then there is no distinction between protected and unprotected
/// sqlite3_value objects and they can be used interchangeably. However,
/// for maximum code portability it is recommended that applications
/// still make the distinction between protected and unprotected
/// sqlite3_value objects even when not strictly required.
///
/// ^The sqlite3_value objects that are passed as parameters into the
/// implementation of [application-defined SQL functions] are protected.
/// ^The sqlite3_value object returned by
/// [sqlite3_column_value()] is unprotected.
/// Unprotected sqlite3_value objects may only be used with
/// [sqlite3_result_value()] and [sqlite3_bind_value()].
/// The [sqlite3_value_blob | sqlite3_value_type()] family of
/// interfaces require protected sqlite3_value objects.
class ValuePointer extends Pointer<Void> {}

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/// This iterator should be [close]d after use.
///
/// [ClosableIterator]s often use resources which should be freed after use.
/// The consumer of the iterator can either manually [close] the iterator, or
/// consume all elements on which the iterator will automatically be closed.
abstract class ClosableIterator<T> extends Iterator<T> {
/// Close this iterator.
void close();
/// Moves to the next element and [close]s the iterator if it was the last
/// element.
bool moveNext();
}
/// This iterable's iterator should be [close]d after use.
///
/// Companion class of [ClosableIterator].
abstract class ClosableIterable<T> extends Iterable<T> {
/// Close this iterables iterator.
void close();
/// Returns a [ClosableIterator] that allows iterating the elements of this
/// [ClosableIterable].
ClosableIterator<T> get iterator;
}

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import "dart:collection";
import "dart:ffi";
import "bindings/bindings.dart";
import "bindings/types.dart";
import "bindings/constants.dart";
import "collections/closable_iterator.dart";
import "ffi/cstring.dart";
/// [Database] represents an open connection to a SQLite database.
///
/// All functions against a database may throw [SQLiteError].
///
/// This database interacts with SQLite synchonously.
class Database {
DatabasePointer _database;
bool _open = false;
/// Open a database located at the file [path].
Database(String path,
[int flags = Flags.SQLITE_OPEN_READWRITE | Flags.SQLITE_OPEN_CREATE]) {
Pointer<DatabasePointer> dbOut = allocate();
CString pathC = CString.allocate(path);
final int resultCode =
bindings.sqlite3_open_v2(pathC, dbOut, flags, fromAddress(0));
_database = dbOut.load();
dbOut.free();
pathC.free();
if (resultCode == Errors.SQLITE_OK) {
_open = true;
} else {
// Even if "open" fails, sqlite3 will still create a database object. We
// can just destroy it.
SQLiteException exception = _loadError(resultCode);
close();
throw exception;
}
}
/// Close the database.
///
/// This should only be called once on a database unless an exception is
/// thrown. It should be called at least once to finalize the database and
/// avoid resource leaks.
void close() {
assert(_open);
final int resultCode = bindings.sqlite3_close_v2(_database);
if (resultCode == Errors.SQLITE_OK) {
_open = false;
} else {
throw _loadError(resultCode);
}
}
/// Execute a query, discarding any returned rows.
void execute(String query) {
Pointer<StatementPointer> statementOut = allocate();
CString queryC = CString.allocate(query);
int resultCode = bindings.sqlite3_prepare_v2(
_database, queryC, -1, statementOut, fromAddress(0));
StatementPointer statement = statementOut.load();
statementOut.free();
queryC.free();
while (resultCode == Errors.SQLITE_ROW || resultCode == Errors.SQLITE_OK) {
resultCode = bindings.sqlite3_step(statement);
}
bindings.sqlite3_finalize(statement);
if (resultCode != Errors.SQLITE_DONE) {
throw _loadError(resultCode);
}
}
/// Evaluate a query and return the resulting rows as an iterable.
Result query(String query) {
Pointer<StatementPointer> statementOut = allocate();
CString queryC = CString.allocate(query);
int resultCode = bindings.sqlite3_prepare_v2(
_database, queryC, -1, statementOut, fromAddress(0));
StatementPointer statement = statementOut.load();
statementOut.free();
queryC.free();
if (resultCode != Errors.SQLITE_OK) {
bindings.sqlite3_finalize(statement);
throw _loadError(resultCode);
}
Map<String, int> columnIndices = {};
int columnCount = bindings.sqlite3_column_count(statement);
for (int i = 0; i < columnCount; i++) {
String columnName =
CString.fromUtf8(bindings.sqlite3_column_name(statement, i));
columnIndices[columnName] = i;
}
return Result._(this, statement, columnIndices);
}
SQLiteException _loadError([int errorCode]) {
String errorMessage = CString.fromUtf8(bindings.sqlite3_errmsg(_database));
if (errorCode == null) {
return SQLiteException(errorMessage);
}
String errorCodeExplanation =
CString.fromUtf8(bindings.sqlite3_errstr(errorCode));
return SQLiteException(
"$errorMessage (Code $errorCode: $errorCodeExplanation)");
}
}
/// [Result] represents a [Database.query]'s result and provides an [Iterable]
/// interface for the results to be consumed.
///
/// Please note that this iterator should be [close]d manually if not all [Row]s
/// are consumed.
class Result extends IterableBase<Row> implements ClosableIterable<Row> {
final Database _database;
final ClosableIterator<Row> _iterator;
final StatementPointer _statement;
final Map<String, int> _columnIndices;
Row _currentRow = null;
Result._(
this._database,
this._statement,
this._columnIndices,
) : _iterator = _ResultIterator(_statement, _columnIndices) {}
void close() => _iterator.close();
ClosableIterator<Row> get iterator => _iterator;
}
class _ResultIterator implements ClosableIterator<Row> {
final StatementPointer _statement;
final Map<String, int> _columnIndices;
Row _currentRow = null;
bool _closed = false;
_ResultIterator(this._statement, this._columnIndices) {}
bool moveNext() {
if (_closed) {
throw SQLiteException("The result has already been closed.");
}
_currentRow?._setNotCurrent();
int stepResult = bindings.sqlite3_step(_statement);
if (stepResult == Errors.SQLITE_ROW) {
_currentRow = Row._(_statement, _columnIndices);
return true;
} else {
close();
return false;
}
}
Row get current {
if (_closed) {
throw SQLiteException("The result has already been closed.");
}
return _currentRow;
}
void close() {
_currentRow?._setNotCurrent();
_closed = true;
bindings.sqlite3_finalize(_statement);
}
}
class Row {
final StatementPointer _statement;
final Map<String, int> _columnIndices;
bool _isCurrentRow = true;
Row._(this._statement, this._columnIndices) {}
/// Reads column [columnName].
///
/// By default it returns a dynamically typed value. If [convert] is set to
/// [Convert.StaticType] the value is converted to the static type computed
/// for the column by the query compiler.
dynamic readColumn(String columnName,
{Convert convert = Convert.DynamicType}) {
return readColumnByIndex(_columnIndices[columnName], convert: convert);
}
/// Reads column [columnName].
///
/// By default it returns a dynamically typed value. If [convert] is set to
/// [Convert.StaticType] the value is converted to the static type computed
/// for the column by the query compiler.
dynamic readColumnByIndex(int columnIndex,
{Convert convert = Convert.DynamicType}) {
_checkIsCurrentRow();
Type dynamicType;
if (convert == Convert.DynamicType) {
dynamicType =
_typeFromCode(bindings.sqlite3_column_type(_statement, columnIndex));
} else {
dynamicType = _typeFromText(CString.fromUtf8(
bindings.sqlite3_column_decltype(_statement, columnIndex)));
}
switch (dynamicType) {
case Type.Integer:
return readColumnByIndexAsInt(columnIndex);
case Type.Text:
return readColumnByIndexAsText(columnIndex);
case Type.Null:
return null;
break;
default:
}
}
/// Reads column [columnName] and converts to [Type.Integer] if not an
/// integer.
int readColumnAsInt(String columnName) {
return readColumnByIndexAsInt(_columnIndices[columnName]);
}
/// Reads column [columnIndex] and converts to [Type.Integer] if not an
/// integer.
int readColumnByIndexAsInt(int columnIndex) {
_checkIsCurrentRow();
return bindings.sqlite3_column_int(_statement, columnIndex);
}
/// Reads column [columnName] and converts to [Type.Text] if not text.
String readColumnAsText(String columnName) {
return readColumnByIndexAsText(_columnIndices[columnName]);
}
/// Reads column [columnIndex] and converts to [Type.Text] if not text.
String readColumnByIndexAsText(int columnIndex) {
_checkIsCurrentRow();
return CString.fromUtf8(
bindings.sqlite3_column_text(_statement, columnIndex));
}
void _checkIsCurrentRow() {
if (!_isCurrentRow) {
throw Exception(
"This row is not the current row, reading data from the non-current"
" row is not supported by sqlite.");
}
}
void _setNotCurrent() {
_isCurrentRow = false;
}
}
Type _typeFromCode(int code) {
switch (code) {
case Types.SQLITE_INTEGER:
return Type.Integer;
case Types.SQLITE_FLOAT:
return Type.Float;
case Types.SQLITE_TEXT:
return Type.Text;
case Types.SQLITE_BLOB:
return Type.Blob;
case Types.SQLITE_NULL:
return Type.Null;
}
throw Exception("Unknown type [$code]");
}
Type _typeFromText(String textRepresentation) {
switch (textRepresentation) {
case "integer":
return Type.Integer;
case "float":
return Type.Float;
case "text":
return Type.Text;
case "blob":
return Type.Blob;
case "null":
return Type.Null;
}
if (textRepresentation == null) return Type.Null;
throw Exception("Unknown type [$textRepresentation]");
}
enum Type { Integer, Float, Text, Blob, Null }
enum Convert { DynamicType, StaticType }
class SQLiteException {
final String message;
SQLiteException(this.message);
String toString() => message;
}

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import "dart:async";
import "dart:ffi";
/// [Arena] manages allocated C memory.
///
/// Arenas are zoned.
class Arena {
Arena();
List<Pointer<Void>> _allocations = [];
/// Bound the lifetime of [ptr] to this [Arena].
T scoped<T extends Pointer>(T ptr) {
_allocations.add(ptr.cast());
return ptr;
}
/// Frees all memory pointed to by [Pointer]s in this arena.
void finalize() {
for (final ptr in _allocations) {
ptr.free();
}
}
/// The last [Arena] in the zone.
factory Arena.current() {
return Zone.current[#_currentArena];
}
}
/// Bound the lifetime of [ptr] to the current [Arena].
T scoped<T extends Pointer>(T ptr) => Arena.current().scoped(ptr);
class RethrownError {
dynamic original;
StackTrace originalStackTrace;
RethrownError(this.original, this.originalStackTrace);
toString() => """RethrownError(${original})
${originalStackTrace}""";
}
/// Runs the [body] in an [Arena] freeing all memory which is [scoped] during
/// execution of [body] at the end of the execution.
R runArena<R>(R Function(Arena) body) {
Arena arena = Arena();
try {
return runZoned(() => body(arena),
zoneValues: {#_currentArena: arena},
onError: (error, st) => throw RethrownError(error, st));
} finally {
arena.finalize();
}
}

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import "dart:convert";
import "dart:ffi";
import "arena.dart";
/// Represents a String in C memory, managed by an [Arena].
class CString extends Pointer<Int8> {
/// Allocates a [CString] in the current [Arena] and populates it with
/// [dartStr].
factory CString(String dartStr) => CString.inArena(Arena.current(), dartStr);
/// Allocates a [CString] in [arena] and populates it with [dartStr].
factory CString.inArena(Arena arena, String dartStr) =>
arena.scoped(CString.allocate(dartStr));
/// Allocate a [CString] not managed in and populates it with [dartStr].
///
/// This [CString] is not managed by an [Arena]. Please ensure to [free] the
/// memory manually!
factory CString.allocate(String dartStr) {
List<int> units = Utf8Encoder().convert(dartStr);
Pointer<Int8> str = allocate(count: units.length + 1);
for (int i = 0; i < units.length; ++i) {
str.elementAt(i).store(units[i]);
}
str.elementAt(units.length).store(0);
return str.cast();
}
/// Read the string for C memory into Dart.
static String fromUtf8(CString str) {
if (str == null) return null;
int len = 0;
while (str.elementAt(++len).load<int>() != 0);
List<int> units = List(len);
for (int i = 0; i < len; ++i) units[i] = str.elementAt(i).load();
return Utf8Decoder().convert(units);
}
}

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// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
import 'dart:ffi' as ffi;
import 'dart:io' show Platform;
String _platformPath(String name, {String path}) {
if (path == null) path = "";
if (Platform.isLinux) return path + "lib" + name + ".so";
if (Platform.isMacOS) return path + "lib" + name + ".dylib";
if (Platform.isWindows) return path + name + ".dll";
throw Exception("Platform not implemented");
}
ffi.DynamicLibrary dlopenPlatformSpecific(String name, {String path}) {
String fullPath = _platformPath(name, path: path);
return ffi.DynamicLibrary.open(fullPath);
}

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samples/ffi/sqlite/pubspec.yaml Normal file
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name: sqlite3
version: 0.0.1
description: >-
Sqlite3 wrapper. Demo for dart:ffi.
author: Daco Harkes <dacoharkes@google.com>, Samir Jindel <sjindel@google.com>
environment:
sdk: '>=2.1.0 <3.0.0'
dev_dependencies:
test: ^1.5.3

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samples/ffi/sqlite/test/sqlite_test.dart Normal file
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// VMOptions=--optimization-counter-threshold=5
import "package:test/test.dart";
import 'package:sqlite3/sqlite.dart';
void main() {
test("sqlite integration test", () {
Database d = Database("test.db");
d.execute("drop table if exists Cookies;");
d.execute("""
create table Cookies (
id integer primary key,
name text not null,
alternative_name text
);""");
d.execute("""
insert into Cookies (id, name, alternative_name)
values
(1,'Chocolade chip cookie', 'Chocolade cookie'),
(2,'Ginger cookie', null),
(3,'Cinnamon roll', null)
;""");
Result result = d.query("""
select
id,
name,
alternative_name,
case
when id=1 then 'foo'
when id=2 then 42
when id=3 then null
end as multi_typed_column
from Cookies
;""");
for (Row r in result) {
int id = r.readColumnAsInt("id");
expect(true, 1 <= id && id <= 3);
String name = r.readColumnByIndex(1);
expect(true, name is String);
String alternativeName = r.readColumn("alternative_name");
expect(true, alternativeName is String || alternativeName == null);
dynamic multiTypedValue = r.readColumn("multi_typed_column");
expect(
true,
multiTypedValue == 42 ||
multiTypedValue == 'foo' ||
multiTypedValue == null);
print("$id $name $alternativeName $multiTypedValue");
}
result = d.query("""
select
id,
name,
alternative_name,
case
when id=1 then 'foo'
when id=2 then 42
when id=3 then null
end as multi_typed_column
from Cookies
;""");
for (Row r in result) {
int id = r.readColumnAsInt("id");
expect(true, 1 <= id && id <= 3);
String name = r.readColumnByIndex(1);
expect(true, name is String);
String alternativeName = r.readColumn("alternative_name");
expect(true, alternativeName is String || alternativeName == null);
dynamic multiTypedValue = r.readColumn("multi_typed_column");
expect(
true,
multiTypedValue == 42 ||
multiTypedValue == 'foo' ||
multiTypedValue == null);
print("$id $name $alternativeName $multiTypedValue");
if (id == 2) {
result.close();
break;
}
}
try {
result.iterator.moveNext();
} on SQLiteException catch (e) {
print("expected exception on accessing result data after close: $e");
}
try {
d.query("""
select
id,
non_existing_column
from Cookies
;""");
} on SQLiteException catch (e) {
print("expected this query to fail: $e");
}
d.execute("drop table Cookies;");
d.close();
});
test("concurrent db open and queries", () {
Database d = Database("test.db");
Database d2 = Database("test.db");
d.execute("drop table if exists Cookies;");
d.execute("""
create table Cookies (
id integer primary key,
name text not null,
alternative_name text
);""");
d.execute("""
insert into Cookies (id, name, alternative_name)
values
(1,'Chocolade chip cookie', 'Chocolade cookie'),
(2,'Ginger cookie', null),
(3,'Cinnamon roll', null)
;""");
Result r = d.query("select * from Cookies;");
Result r2 = d2.query("select * from Cookies;");
r.iterator..moveNext();
r2.iterator..moveNext();
r.iterator..moveNext();
Result r3 = d2.query("select * from Cookies;");
r3.iterator..moveNext();
expect(2, r.iterator.current.readColumn("id"));
expect(1, r2.iterator.current.readColumn("id"));
expect(1, r3.iterator.current.readColumn("id"));
r.close();
r2.close();
r3.close();
d.close();
d2.close();
});
test("stress test", () {
Database d = Database("test.db");
d.execute("drop table if exists Cookies;");
d.execute("""
create table Cookies (
id integer primary key,
name text not null,
alternative_name text
);""");
int repeats = 100;
for (int i = 0; i < repeats; i++) {
d.execute("""
insert into Cookies (name, alternative_name)
values
('Chocolade chip cookie', 'Chocolade cookie'),
('Ginger cookie', null),
('Cinnamon roll', null)
;""");
}
Result r = d.query("select count(*) from Cookies;");
int count = r.first.readColumnByIndexAsInt(0);
expect(count, 3 * repeats);
r.close();
d.close();
});
}