exp/sql{,/driver}: new database packages

R=gustavo, rsc, borman, dave, kevlar, nigeltao, dvyukov, kardianos, fw, r, r, david.crawshaw
CC=golang-dev
https://golang.org/cl/4973055

3 files changed, 342 insertions, 0 deletions

diff --git a/src/pkg/exp/sql/driver/Makefile b/src/pkg/exp/sql/driver/Makefile
new file mode 100644
index 0000000000..fce3f2c27c
--- /dev/null
+++ b/src/pkg/exp/sql/driver/Makefile
@@ -0,0 +1,12 @@
+# Copyright 2011 The Go Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+include ../../../../Make.inc
+
+TARG=exp/sql/driver
+GOFILES=\
+	driver.go\
+	types.go\
+
+include ../../../../Make.pkg
diff --git a/src/pkg/exp/sql/driver/driver.go b/src/pkg/exp/sql/driver/driver.go
new file mode 100644
index 0000000000..7508b19fa1
--- /dev/null
+++ b/src/pkg/exp/sql/driver/driver.go
@@ -0,0 +1,169 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package driver defines interfaces to be implemented by database
+// drivers as used by package sql.
+//
+// Code simply using databases should use package sql.
+//
+// Drivers only need to be aware of a subset of Go's types.  The db package
+// will convert all types into one of the following:
+//
+//   int64
+//   float64
+//   bool
+//   nil
+//   []byte
+//   string   [*] everywhere except from Rows.Next.
+//
+package driver
+
+import (
+	"os"
+)
+
+// Driver is the interface that must be implemented by a database
+// driver.
+type Driver interface {
+	// Open returns a new or cached connection to the database.
+	// The name is a string in a driver-specific format.
+	//
+	// The returned connection is only used by one goroutine at a
+	// time.
+	Open(name string) (Conn, os.Error)
+}
+
+// Execer is an optional interface that may be implemented by a Driver
+// or a Conn.
+//
+// If a Driver does not implement Execer, the sql package's DB.Exec
+// method first obtains a free connection from its free pool or from
+// the driver's Open method. Execer should only be implemented by
+// drivers that can provide a more efficient implementation.
+//
+// If a Conn does not implement Execer, the db package's DB.Exec will
+// first prepare a query, execute the statement, and then close the
+// statement.
+//
+// All arguments are of a subset type as defined in the package docs.
+type Execer interface {
+	Exec(query string, args []interface{}) (Result, os.Error)
+}
+
+// Conn is a connection to a database. It is not used concurrently
+// by multiple goroutines.
+//
+// Conn is assumed to be stateful.
+type Conn interface {
+	// Prepare returns a prepared statement, bound to this connection.
+	Prepare(query string) (Stmt, os.Error)
+
+	// Close invalidates and potentially stops any current
+	// prepared statements and transactions, marking this
+	// connection as no longer in use.  The driver may cache or
+	// close its underlying connection to its database.
+	Close() os.Error
+
+	// Begin starts and returns a new transaction.
+	Begin() (Tx, os.Error)
+}
+
+// Result is the result of a query execution.
+type Result interface {
+	// LastInsertId returns the database's auto-generated ID
+	// after, for example, an INSERT into a table with primary
+	// key.
+	LastInsertId() (int64, os.Error)
+
+	// RowsAffected returns the number of rows affected by the
+	// query.
+	RowsAffected() (int64, os.Error)
+}
+
+// Stmt is a prepared statement. It is bound to a Conn and not
+// used by multiple goroutines concurrently.
+type Stmt interface {
+	// Close closes the statement.
+	Close() os.Error
+
+	// NumInput returns the number of placeholder parameters.
+	NumInput() int
+
+	// Exec executes a query that doesn't return rows, such
+	// as an INSERT or UPDATE.  The args are all of a subset
+	// type as defined above.
+	Exec(args []interface{}) (Result, os.Error)
+
+	// Exec executes a query that may return rows, such as a
+	// SELECT.  The args of all of a subset type as defined above.
+	Query(args []interface{}) (Rows, os.Error)
+}
+
+// ColumnConverter may be optionally implemented by Stmt if the
+// the statement is aware of its own columns' types and can
+// convert from any type to a driver subset type.
+type ColumnConverter interface {
+	// ColumnConverter returns a ValueConverter for the provided
+	// column index.  If the type of a specific column isn't known
+	// or shouldn't be handled specially, DefaultValueConverter
+	// can be returned.
+	ColumnConverter(idx int) ValueConverter
+}
+
+// Rows is an iterator over an executed query's results.
+type Rows interface {
+	// Columns returns the names of the columns. The number of
+	// columns of the result is inferred from the length of the
+	// slice.  If a particular column name isn't known, an empty
+	// string should be returned for that entry.
+	Columns() []string
+
+	// Close closes the rows iterator.
+	Close() os.Error
+
+	// Next is called to populate the next row of data into
+	// the provided slice. The provided slice will be the same
+	// size as the Columns() are wide.
+	//
+	// The dest slice may be populated with only with values
+	// of subset types defined above, but excluding string.
+	// All string values must be converted to []byte.
+	Next(dest []interface{}) os.Error
+}
+
+// Tx is a transaction.
+type Tx interface {
+	Commit() os.Error
+	Rollback() os.Error
+}
+
+// RowsAffected implements Result for an INSERT or UPDATE operation
+// which mutates a number of rows.
+type RowsAffected int64
+
+var _ Result = RowsAffected(0)
+
+func (RowsAffected) LastInsertId() (int64, os.Error) {
+	return 0, os.NewError("no LastInsertId available")
+}
+
+func (v RowsAffected) RowsAffected() (int64, os.Error) {
+	return int64(v), nil
+}
+
+// DDLSuccess is a pre-defined Result for drivers to return when a DDL
+// command succeeds.
+var DDLSuccess ddlSuccess
+
+type ddlSuccess struct{}
+
+var _ Result = ddlSuccess{}
+
+func (ddlSuccess) LastInsertId() (int64, os.Error) {
+	return 0, os.NewError("no LastInsertId available after DDL statement")
+}
+
+func (ddlSuccess) RowsAffected() (int64, os.Error) {
+	return 0, os.NewError("no RowsAffected available after DDL statement")
+}
diff --git a/src/pkg/exp/sql/driver/types.go b/src/pkg/exp/sql/driver/types.go
new file mode 100644
index 0000000000..5521d5389c
--- /dev/null
+++ b/src/pkg/exp/sql/driver/types.go
@@ -0,0 +1,161 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package driver
+
+import (
+	"fmt"
+	"os"
+	"reflect"
+	"strconv"
+)
+
+// ValueConverter is the interface providing the ConvertValue method.
+type ValueConverter interface {
+	// ConvertValue converts a value to a restricted subset type.
+	ConvertValue(v interface{}) (interface{}, os.Error)
+}
+
+// Bool is a ValueConverter that converts input values to bools.
+//
+// The conversion rules are:
+//  - .... TODO(bradfitz): TBD
+var Bool boolType
+
+type boolType struct{}
+
+var _ ValueConverter = boolType{}
+
+func (boolType) ConvertValue(v interface{}) (interface{}, os.Error) {
+	return nil, fmt.Errorf("TODO(bradfitz): bool conversions")
+}
+
+// Int32 is a ValueConverter that converts input values to int64,
+// respecting the limits of an int32 value.
+var Int32 int32Type
+
+type int32Type struct{}
+
+var _ ValueConverter = int32Type{}
+
+func (int32Type) ConvertValue(v interface{}) (interface{}, os.Error) {
+	rv := reflect.ValueOf(v)
+	switch rv.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		i64 := rv.Int()
+		if i64 > (1<<31)-1 || i64 < -(1<<31) {
+			return nil, fmt.Errorf("sql/driver: value %d overflows int32", v)
+		}
+		return i64, nil
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		u64 := rv.Uint()
+		if u64 > (1<<31)-1 {
+			return nil, fmt.Errorf("sql/driver: value %d overflows int32", v)
+		}
+		return int64(u64), nil
+	case reflect.String:
+		i, err := strconv.Atoi(rv.String())
+		if err != nil {
+			return nil, fmt.Errorf("sql/driver: value %q can't be converted to int32", v)
+		}
+		return int64(i), nil
+	}
+	return nil, fmt.Errorf("sql/driver: unsupported value %v (type %T) converting to int32", v, v)
+}
+
+// String is a ValueConverter that converts its input to a string.
+// If the value is already a string or []byte, it's unchanged.
+// If the value is of another type, conversion to string is done
+// with fmt.Sprintf("%v", v).
+var String stringType
+
+type stringType struct{}
+
+func (stringType) ConvertValue(v interface{}) (interface{}, os.Error) {
+	switch v.(type) {
+	case string, []byte:
+		return v, nil
+	}
+	return fmt.Sprintf("%v", v), nil
+}
+
+// IsParameterSubsetType reports whether v is of a valid type for a
+// parameter. These types are:
+//
+//   int64
+//   float64
+//   bool
+//   nil
+//   []byte
+//   string
+//
+// This is the ame list as IsScanSubsetType, with the addition of
+// string.
+func IsParameterSubsetType(v interface{}) bool {
+	if IsScanSubsetType(v) {
+		return true
+	}
+	if _, ok := v.(string); ok {
+		return true
+	}
+	return false
+}
+
+// IsScanSubsetType reports whether v is of a valid type for a
+// value populated by Rows.Next. These types are:
+//
+//   int64
+//   float64
+//   bool
+//   nil
+//   []byte
+//
+// This is the same list as IsParameterSubsetType, without string.
+func IsScanSubsetType(v interface{}) bool {
+	if v == nil {
+		return true
+	}
+	switch v.(type) {
+	case int64, float64, []byte, bool:
+		return true
+	}
+	return false
+}
+
+// DefaultParameterConverter is the default implementation of
+// ValueConverter that's used when a Stmt doesn't implement
+// ColumnConverter.
+//
+// DefaultParameterConverter returns the given value directly if
+// IsSubsetType(value).  Otherwise integer type are converted to
+// int64, floats to float64, and strings to []byte.  Other types are
+// an error.
+var DefaultParameterConverter defaultConverter
+
+type defaultConverter struct{}
+
+var _ ValueConverter = defaultConverter{}
+
+func (defaultConverter) ConvertValue(v interface{}) (interface{}, os.Error) {
+	if IsParameterSubsetType(v) {
+		return v, nil
+	}
+
+	rv := reflect.ValueOf(v)
+	switch rv.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return rv.Int(), nil
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32:
+		return int64(rv.Uint()), nil
+	case reflect.Uint64:
+		u64 := rv.Uint()
+		if u64 >= 1<<63 {
+			return nil, fmt.Errorf("uint64 values with high bit set are not supported")
+		}
+		return int64(u64), nil
+	case reflect.Float32, reflect.Float64:
+		return rv.Float(), nil
+	}
+	return nil, fmt.Errorf("unsupported type %s", rv.Kind())
+}