Add database/sql driver (eatonphil#21)

* Add driver and example

* Single backend for all connections

* Fixes for lint

* Add database/sql driver to readme

README.md

@@ -44,6 +44,67 @@ ok
 ok
 ```
 
+## Using the database/sql driver
+
+See cmd/sqlexample/main.go:
+
+```go
+package main
+
+import (
+	"database/sql"
+	"fmt"
+
+	_ "github.com/eatonphil/gosql"
+)
+
+func main() {
+	db, err := sql.Open("postgres", "")
+	if err != nil {
+		panic(err)
+	}
+	defer db.Close()
+
+	_, err = db.Query("CREATE TABLE users (name TEXT, age INT);")
+	if err != nil {
+		panic(err)
+	}
+
+	_, err = db.Query("INSERT INTO users VALUES ('Terry', 45);")
+	if err != nil {
+		panic(err)
+	}
+
+	_, err = db.Query("INSERT INTO users VALUES ('Anette', 57);")
+	if err != nil {
+		panic(err)
+	}
+
+	rows, err := db.Query("SELECT name, age FROM users;")
+	if err != nil {
+		panic(err)
+	}
+
+	var name string
+	var age uint64
+	defer rows.Close()
+	for rows.Next() {
+		err := rows.Scan(&name, &age)
+		if err != nil {
+			panic(err)
+		}
+
+		fmt.Printf("Name: %s, Age: %d\n", name, age)
+	}
+
+	if err = rows.Err(); err != nil {
+		panic(err)
+	}
+}
+```
+
+Parameterization is not currently supported.
+
 ## Architecture
 
 * [cmd/main.go](./cmd/main.go)

backend.go

@@ -54,6 +54,8 @@ type TableMetadata struct {
 
 type Backend interface {
 	CreateTable(*CreateTableStatement) error
+	DropTable(*DropTableStatement) error
+	CreateIndex(*CreateIndexStatement) error
 	Insert(*InsertStatement) error
 	Select(*SelectStatement) (*Results, error)
 	GetTables() []TableMetadata

cmd/sqlexample/main.go

@@ -0,0 +1,52 @@
+package main
+
+import (
+	"database/sql"
+	"fmt"
+
+	_ "github.com/eatonphil/gosql"
+)
+
+func main() {
+	db, err := sql.Open("postgres", "")
+	if err != nil {
+		panic(err)
+	}
+	defer db.Close()
+
+	_, err = db.Query("CREATE TABLE users (name TEXT, age INT);")
+	if err != nil {
+		panic(err)
+	}
+
+	_, err = db.Query("INSERT INTO users VALUES ('Terry', 45);")
+	if err != nil {
+		panic(err)
+	}
+
+	_, err = db.Query("INSERT INTO users VALUES ('Anette', 57);")
+	if err != nil {
+		panic(err)
+	}
+
+	rows, err := db.Query("SELECT name, age FROM users;")
+	if err != nil {
+		panic(err)
+	}
+
+	var name string
+	var age uint64
+	defer rows.Close()
+	for rows.Next() {
+		err := rows.Scan(&name, &age)
+		if err != nil {
+			panic(err)
+		}
+
+		fmt.Printf("Name: %s, Age: %d\n", name, age)
+	}
+
+	if err = rows.Err(); err != nil {
+		panic(err)
+	}
+}

driver.go

@@ -0,0 +1,149 @@
+package gosql
+
+import (
+	"database/sql"
+	"database/sql/driver"
+	"fmt"
+	"io"
+)
+
+type Rows struct {
+	columns []ResultColumn
+	index   uint64
+	rows    [][]Cell
+}
+
+func (r *Rows) Columns() []string {
+	columns := []string{}
+	for _, c := range r.columns {
+		columns = append(columns, c.Name)
+	}
+
+	return columns
+}
+
+func (r *Rows) Close() error {
+	r.index = uint64(len(r.rows))
+	return nil
+}
+
+func (r *Rows) Next(dest []driver.Value) error {
+	if r.index >= uint64(len(r.rows)) {
+		return io.EOF
+	}
+
+	row := r.rows[r.index]
+
+	for idx, cell := range row {
+		typ := r.columns[idx].Type
+		switch typ {
+		case IntType:
+			i := cell.AsInt()
+			if i == nil {
+				dest[idx] = i
+			} else {
+				dest[idx] = *i
+			}
+		case TextType:
+			s := cell.AsText()
+			if s == nil {
+				dest[idx] = s
+			} else {
+				dest[idx] = *s
+			}
+		case BoolType:
+			b := cell.AsBool()
+			if b == nil {
+				dest[idx] = b
+			} else {
+				dest[idx] = b
+			}
+		}
+	}
+
+	r.index++
+	return nil
+}
+
+type Conn struct {
+	bkd Backend
+}
+
+func (dc *Conn) doSelect(slct *SelectStatement) (driver.Rows, error) {
+	results, err := dc.bkd.Select(slct)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Rows{
+		rows:    results.Rows,
+		columns: results.Columns,
+		index:   0,
+	}, nil
+}
+
+func (dc *Conn) Query(query string, args []driver.Value) (driver.Rows, error) {
+	if len(args) > 0 {
+		// TODO: support parameterization
+		panic("Parameterization not supported")
+	}
+
+	parser := Parser{}
+	ast, err := parser.Parse(query)
+	if err != nil {
+		return nil, fmt.Errorf("Error while parsing: %s", err)
+	}
+
+	// NOTE: ignorning all but the first statement
+	stmt := ast.Statements[0]
+	switch stmt.Kind {
+	case CreateIndexKind:
+		err = dc.bkd.CreateIndex(stmt.CreateIndexStatement)
+		if err != nil {
+			return nil, fmt.Errorf("Error adding index on table: %s", err)
+		}
+	case CreateTableKind:
+		err = dc.bkd.CreateTable(stmt.CreateTableStatement)
+		if err != nil {
+			return nil, fmt.Errorf("Error creating table: %s", err)
+		}
+	case DropTableKind:
+		err = dc.bkd.DropTable(stmt.DropTableStatement)
+		if err != nil {
+			return nil, fmt.Errorf("Error dropping table: %s", err)
+		}
+	case InsertKind:
+		err = dc.bkd.Insert(stmt.InsertStatement)
+		if err != nil {
+			return nil, fmt.Errorf("Error inserting values: %s", err)
+		}
+	case SelectKind:
+		return dc.doSelect(stmt.SelectStatement)
+	}
+
+	return nil, nil
+}
+
+func (dc *Conn) Prepare(query string) (driver.Stmt, error) {
+	panic("Prepare not implemented")
+}
+
+func (dc *Conn) Begin() (driver.Tx, error) {
+	panic("Begin not implemented")
+}
+
+func (dc *Conn) Close() error {
+	return nil
+}
+
+type Driver struct {
+	bkd Backend
+}
+
+func (d *Driver) Open(name string) (driver.Conn, error) {
+	return &Conn{d.bkd}, nil
+}
+
+func init() {
+	sql.Register("postgres", &Driver{NewMemoryBackend()})
+}