[experiment] add alternative wasm sqlite3 implementation available via build-tag (#2863)

This allows for building GoToSocial with [SQLite transpiled to WASM](https://github.com/ncruces/go-sqlite3) and accessed through [Wazero](https://wazero.io/).

vendor/github.com/ncruces/go-sqlite3/value.go

@@ -0,0 +1,236 @@
+package sqlite3
+
+import (
+	"encoding/json"
+	"math"
+	"strconv"
+	"time"
+
+	"github.com/ncruces/go-sqlite3/internal/util"
+)
+
+// Value is any value that can be stored in a database table.
+//
+// https://sqlite.org/c3ref/value.html
+type Value struct {
+	c      *Conn
+	handle uint32
+	unprot bool
+	copied bool
+}
+
+func (v Value) protected() uint64 {
+	if v.unprot {
+		panic(util.ValueErr)
+	}
+	return uint64(v.handle)
+}
+
+// Dup makes a copy of the SQL value and returns a pointer to that copy.
+//
+// https://sqlite.org/c3ref/value_dup.html
+func (v Value) Dup() *Value {
+	r := v.c.call("sqlite3_value_dup", uint64(v.handle))
+	return &Value{
+		c:      v.c,
+		copied: true,
+		handle: uint32(r),
+	}
+}
+
+// Close frees an SQL value previously obtained by [Value.Dup].
+//
+// https://sqlite.org/c3ref/value_dup.html
+func (dup *Value) Close() error {
+	if !dup.copied {
+		panic(util.ValueErr)
+	}
+	dup.c.call("sqlite3_value_free", uint64(dup.handle))
+	dup.handle = 0
+	return nil
+}
+
+// Type returns the initial datatype of the value.
+//
+// https://sqlite.org/c3ref/value_blob.html
+func (v Value) Type() Datatype {
+	r := v.c.call("sqlite3_value_type", v.protected())
+	return Datatype(r)
+}
+
+// Type returns the numeric datatype of the value.
+//
+// https://sqlite.org/c3ref/value_blob.html
+func (v Value) NumericType() Datatype {
+	r := v.c.call("sqlite3_value_numeric_type", v.protected())
+	return Datatype(r)
+}
+
+// Bool returns the value as a bool.
+// SQLite does not have a separate boolean storage class.
+// Instead, boolean values are retrieved as integers,
+// with 0 converted to false and any other value to true.
+//
+// https://sqlite.org/c3ref/value_blob.html
+func (v Value) Bool() bool {
+	return v.Int64() != 0
+}
+
+// Int returns the value as an int.
+//
+// https://sqlite.org/c3ref/value_blob.html
+func (v Value) Int() int {
+	return int(v.Int64())
+}
+
+// Int64 returns the value as an int64.
+//
+// https://sqlite.org/c3ref/value_blob.html
+func (v Value) Int64() int64 {
+	r := v.c.call("sqlite3_value_int64", v.protected())
+	return int64(r)
+}
+
+// Float returns the value as a float64.
+//
+// https://sqlite.org/c3ref/value_blob.html
+func (v Value) Float() float64 {
+	r := v.c.call("sqlite3_value_double", v.protected())
+	return math.Float64frombits(r)
+}
+
+// Time returns the value as a [time.Time].
+//
+// https://sqlite.org/c3ref/value_blob.html
+func (v Value) Time(format TimeFormat) time.Time {
+	var a any
+	switch v.Type() {
+	case INTEGER:
+		a = v.Int64()
+	case FLOAT:
+		a = v.Float()
+	case TEXT, BLOB:
+		a = v.Text()
+	case NULL:
+		return time.Time{}
+	default:
+		panic(util.AssertErr())
+	}
+	t, _ := format.Decode(a)
+	return t
+}
+
+// Text returns the value as a string.
+//
+// https://sqlite.org/c3ref/value_blob.html
+func (v Value) Text() string {
+	return string(v.RawText())
+}
+
+// Blob appends to buf and returns
+// the value as a []byte.
+//
+// https://sqlite.org/c3ref/value_blob.html
+func (v Value) Blob(buf []byte) []byte {
+	return append(buf, v.RawBlob()...)
+}
+
+// RawText returns the value as a []byte.
+// The []byte is owned by SQLite and may be invalidated by
+// subsequent calls to [Value] methods.
+//
+// https://sqlite.org/c3ref/value_blob.html
+func (v Value) RawText() []byte {
+	r := v.c.call("sqlite3_value_text", v.protected())
+	return v.rawBytes(uint32(r))
+}
+
+// RawBlob returns the value as a []byte.
+// The []byte is owned by SQLite and may be invalidated by
+// subsequent calls to [Value] methods.
+//
+// https://sqlite.org/c3ref/value_blob.html
+func (v Value) RawBlob() []byte {
+	r := v.c.call("sqlite3_value_blob", v.protected())
+	return v.rawBytes(uint32(r))
+}
+
+func (v Value) rawBytes(ptr uint32) []byte {
+	if ptr == 0 {
+		return nil
+	}
+
+	r := v.c.call("sqlite3_value_bytes", v.protected())
+	return util.View(v.c.mod, ptr, r)
+}
+
+// Pointer gets the pointer associated with this value,
+// or nil if it has no associated pointer.
+func (v Value) Pointer() any {
+	r := v.c.call("sqlite3_value_pointer_go", v.protected())
+	return util.GetHandle(v.c.ctx, uint32(r))
+}
+
+// JSON parses a JSON-encoded value
+// and stores the result in the value pointed to by ptr.
+func (v Value) JSON(ptr any) error {
+	var data []byte
+	switch v.Type() {
+	case NULL:
+		data = append(data, "null"...)
+	case TEXT:
+		data = v.RawText()
+	case BLOB:
+		data = v.RawBlob()
+	case INTEGER:
+		data = strconv.AppendInt(nil, v.Int64(), 10)
+	case FLOAT:
+		data = strconv.AppendFloat(nil, v.Float(), 'g', -1, 64)
+	default:
+		panic(util.AssertErr())
+	}
+	return json.Unmarshal(data, ptr)
+}
+
+// NoChange returns true if and only if the value is unchanged
+// in a virtual table update operatiom.
+//
+// https://sqlite.org/c3ref/value_blob.html
+func (v Value) NoChange() bool {
+	r := v.c.call("sqlite3_value_nochange", v.protected())
+	return r != 0
+}
+
+// InFirst returns the first element
+// on the right-hand side of an IN constraint.
+//
+// https://sqlite.org/c3ref/vtab_in_first.html
+func (v Value) InFirst() (Value, error) {
+	defer v.c.arena.mark()()
+	valPtr := v.c.arena.new(ptrlen)
+	r := v.c.call("sqlite3_vtab_in_first", uint64(v.handle), uint64(valPtr))
+	if err := v.c.error(r); err != nil {
+		return Value{}, err
+	}
+	return Value{
+		c:      v.c,
+		handle: util.ReadUint32(v.c.mod, valPtr),
+	}, nil
+}
+
+// InNext returns the next element
+// on the right-hand side of an IN constraint.
+//
+// https://sqlite.org/c3ref/vtab_in_first.html
+func (v Value) InNext() (Value, error) {
+	defer v.c.arena.mark()()
+	valPtr := v.c.arena.new(ptrlen)
+	r := v.c.call("sqlite3_vtab_in_next", uint64(v.handle), uint64(valPtr))
+	if err := v.c.error(r); err != nil {
+		return Value{}, err
+	}
+	return Value{
+		c:      v.c,
+		handle: util.ReadUint32(v.c.mod, valPtr),
+	}, nil
+}