Custom collating sequences.

func.go

@@ -8,6 +8,21 @@ import (
 	"github.com/tetratelabs/wazero/api"
 )
 
+// CreateCollation defines a new collating sequence.
+//
+// https://www.sqlite.org/c3ref/create_collation.html
+func (c *Conn) CreateCollation(name string, fn func(a, b []byte) int) error {
+	namePtr := c.arena.string(name)
+	funcPtr := util.AddHandle(c.ctx, fn)
+	r := c.call(c.api.createCollation,
+		uint64(c.handle), uint64(namePtr), uint64(funcPtr))
+	if err := c.error(r); err != nil {
+		util.DelHandle(c.ctx, funcPtr)
+		return err
+	}
+	return nil
+}
+
 func exportHostFunctions(env wazero.HostModuleBuilder) wazero.HostModuleBuilder {
 	util.ExportFuncVI(env, "go_destroy", cbDestroy)
 	util.ExportFuncIIIIII(env, "go_compare", cbCompare)
@@ -19,10 +34,13 @@ func exportHostFunctions(env wazero.HostModuleBuilder) wazero.HostModuleBuilder
 	return env
 }
 
-func cbDestroy(ctx context.Context, mod api.Module, pArg uint32) {}
+func cbDestroy(ctx context.Context, mod api.Module, pArg uint32) {
+	util.DelHandle(ctx, pArg)
+}
 
 func cbCompare(ctx context.Context, mod api.Module, pArg, nKey1, pKey1, nKey2, pKey2 uint32) uint32 {
-	return 0
+	fn := util.GetHandle(ctx, pArg).(func(a, b []byte) int)
+	return uint32(fn(util.View(mod, pKey1, uint64(nKey1)), util.View(mod, pKey2, uint64(nKey2))))
 }
 
 func cbFunc(ctx context.Context, mod api.Module, pCtx, nArg, pArg uint32) {}

func_test.go

@@ -0,0 +1,64 @@
+package sqlite3_test
+
+import (
+	"fmt"
+	"log"
+
+	"golang.org/x/text/collate"
+	"golang.org/x/text/language"
+
+	"github.com/ncruces/go-sqlite3"
+	_ "github.com/ncruces/go-sqlite3/embed"
+)
+
+func ExampleConn_CreateCollation() {
+	db, err := sqlite3.Open(memory)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	err = db.Exec(`CREATE TABLE IF NOT EXISTS words (word VARCHAR(10))`)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	err = db.Exec(`INSERT INTO words (word) VALUES ('côte'), ('cote'), ('coter'), ('coté'), ('cotée'), ('côté')`)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	err = db.CreateCollation("french", collate.New(language.French).Compare)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	stmt, _, err := db.Prepare(`SELECT word FROM words ORDER BY word COLLATE french`)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer stmt.Close()
+
+	for stmt.Step() {
+		fmt.Println(stmt.ColumnText(0))
+	}
+	if err := stmt.Err(); err != nil {
+		log.Fatal(err)
+	}
+
+	err = stmt.Close()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	err = db.Close()
+	if err != nil {
+		log.Fatal(err)
+	}
+	// Output:
+	// cote
+	// coté
+	// côte
+	// côté
+	// cotée
+	// coter
+}

go.mod

@@ -8,6 +8,7 @@ require (
 	github.com/tetratelabs/wazero v1.2.1
 	golang.org/x/sync v0.3.0
 	golang.org/x/sys v0.9.0
+	golang.org/x/text v0.10.0
 )
 
 retract v0.4.0 // tagged from the wrong branch

go.sum

@@ -8,3 +8,5 @@ golang.org/x/sync v0.3.0 h1:ftCYgMx6zT/asHUrPw8BLLscYtGznsLAnjq5RH9P66E=
 golang.org/x/sync v0.3.0/go.mod h1:FU7BRWz2tNW+3quACPkgCx/L+uEAv1htQ0V83Z9Rj+Y=
 golang.org/x/sys v0.9.0 h1:KS/R3tvhPqvJvwcKfnBHJwwthS11LRhmM5D59eEXa0s=
 golang.org/x/sys v0.9.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/text v0.10.0 h1:UpjohKhiEgNc0CSauXmwYftY1+LlaC75SJwh0SgCX58=
+golang.org/x/text v0.10.0/go.mod h1:TvPlkZtksWOMsz7fbANvkp4WM8x/WCo/om8BMLbz+aE=

module.go

@@ -155,6 +155,7 @@ func newModule(mod api.Module) (m *module, err error) {
 		changes:         getFun("sqlite3_changes64"),
 		lastRowid:       getFun("sqlite3_last_insert_rowid"),
 		autocommit:      getFun("sqlite3_get_autocommit"),
+		createCollation: getFun("sqlite3_create_go_collation"),
 	}
 	if err != nil {
 		return nil, err
@@ -350,5 +351,6 @@ type sqliteAPI struct {
 	changes         api.Function
 	lastRowid       api.Function
 	autocommit      api.Function
+	createCollation api.Function
 	destructor      uint32
 }