Adding the challenge 0401

0401/assert.go

@@ -0,0 +1,9 @@
+package db0401
+
+func check(cond bool) {
+	if !cond {
+		panic("assertion failure")
+	}
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/

0401/cell.go

@@ -0,0 +1,57 @@
+package db0401
+
+import (
+	"encoding/binary"
+	"errors"
+	"slices"
+)
+
+type CellType uint8
+
+const (
+	TypeI64 CellType = 1
+	TypeStr CellType = 2
+)
+
+type Cell struct {
+	Type CellType
+	I64  int64
+	Str  []byte
+}
+
+func (cell *Cell) Encode(toAppend []byte) []byte {
+	switch cell.Type {
+	case TypeI64:
+		return binary.LittleEndian.AppendUint64(toAppend, uint64(cell.I64))
+	case TypeStr:
+		toAppend = binary.LittleEndian.AppendUint32(toAppend, uint32(len(cell.Str)))
+		return append(toAppend, cell.Str...)
+	default:
+		panic("unreachable")
+	}
+}
+
+func (cell *Cell) Decode(data []byte) (rest []byte, err error) {
+	switch cell.Type {
+	case TypeI64:
+		if len(data) < 8 {
+			return data, errors.New("expect more data")
+		}
+		cell.I64 = int64(binary.LittleEndian.Uint64(data[0:8]))
+		return data[8:], nil
+	case TypeStr:
+		if len(data) < 4 {
+			return data, errors.New("expect more data")
+		}
+		size := int(binary.LittleEndian.Uint32(data[0:4]))
+		if len(data) < 4+size {
+			return data, errors.New("expect more data")
+		}
+		cell.Str = slices.Clone(data[4 : 4+size])
+		return data[4+size:], nil
+	default:
+		panic("unreachable")
+	}
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/

0401/cell_test.go

@@ -0,0 +1,27 @@
+package db0401
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTableCell(t *testing.T) {
+	cell := Cell{Type: TypeI64, I64: -2}
+	data := []byte{0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff}
+	assert.Equal(t, data, cell.Encode(nil))
+	decoded := Cell{Type: TypeI64}
+	rest, err := decoded.Decode(data)
+	assert.True(t, len(rest) == 0 && err == nil)
+	assert.Equal(t, cell, decoded)
+
+	cell = Cell{Type: TypeStr, Str: []byte("asdf")}
+	data = []byte{4, 0, 0, 0, 'a', 's', 'd', 'f'}
+	assert.Equal(t, data, cell.Encode(nil))
+	decoded = Cell{Type: TypeStr}
+	rest, err = decoded.Decode(data)
+	assert.True(t, len(rest) == 0 && err == nil)
+	assert.Equal(t, cell, decoded)
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/

0401/kv.go

@@ -0,0 +1,31 @@
+package db0401
+
+type KV struct {
+	log  Log
+	keys [][]byte
+	vals [][]byte
+}
+
+func (kv *KV) Open() error
+
+func (kv *KV) Close() error { return kv.log.Close() }
+
+func (kv *KV) Get(key []byte) (val []byte, ok bool, err error)
+
+type UpdateMode int
+
+const (
+	ModeUpsert UpdateMode = 0 // insert or update
+	ModeInsert UpdateMode = 1 // insert new
+	ModeUpdate UpdateMode = 2 // update existing
+)
+
+func (kv *KV) SetEx(key []byte, val []byte, mode UpdateMode) (updated bool, err error)
+
+func (kv *KV) Set(key []byte, val []byte) (updated bool, err error) {
+	return kv.SetEx(key, val, ModeUpsert)
+}
+
+func (kv *KV) Del(key []byte) (deleted bool, err error)
+
+// QzBQWVJJOUhU https://trialofcode.org/

0401/kv_entry.go

@@ -0,0 +1,63 @@
+package db0401
+
+import (
+	"encoding/binary"
+	"errors"
+	"hash/crc32"
+	"io"
+)
+
+type Entry struct {
+	key     []byte
+	val     []byte
+	deleted bool
+}
+
+func (ent *Entry) Encode() []byte {
+	data := make([]byte, 4+4+4+1+len(ent.key)+len(ent.val))
+	binary.LittleEndian.PutUint32(data[4:8], uint32(len(ent.key)))
+	copy(data[4+4+4+1:], ent.key)
+	if ent.deleted {
+		data[4+4+4] = 1
+	} else {
+		binary.LittleEndian.PutUint32(data[8:12], uint32(len(ent.val)))
+		copy(data[4+4+4+1+len(ent.key):], ent.val)
+	}
+	binary.LittleEndian.PutUint32(data[0:4], crc32.ChecksumIEEE(data[4:]))
+	return data
+}
+
+var ErrBadSum = errors.New("bad checksum")
+
+func (ent *Entry) Decode(r io.Reader) error {
+	var header [4 + 4 + 4 + 1]byte
+	if _, err := io.ReadFull(r, header[:]); err != nil {
+		return err
+	}
+	klen := int(binary.LittleEndian.Uint32(header[4:8]))
+	vlen := int(binary.LittleEndian.Uint32(header[8:12]))
+	deleted := header[4+4+4]
+
+	data := make([]byte, klen+vlen)
+	if _, err := io.ReadFull(r, data); err != nil {
+		return err
+	}
+
+	h := crc32.NewIEEE()
+	h.Write(header[4:])
+	h.Write(data)
+	if h.Sum32() != binary.LittleEndian.Uint32(header[0:4]) {
+		return ErrBadSum
+	}
+
+	ent.key = data[:klen]
+	if deleted != 0 {
+		ent.deleted = true
+	} else {
+		ent.deleted = false
+		ent.val = data[klen:]
+	}
+	return nil
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/

0401/kv_test.go

@@ -0,0 +1,158 @@
+package db0401
+
+import (
+	"bytes"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestKVBasic(t *testing.T) {
+	kv := KV{}
+	kv.log.FileName = ".test_db"
+	defer os.Remove(kv.log.FileName)
+
+	os.Remove(kv.log.FileName)
+	err := kv.Open()
+	assert.Nil(t, err)
+	defer kv.Close()
+
+	updated, err := kv.Set([]byte("k1"), []byte("v1"))
+	assert.True(t, updated && err == nil)
+
+	val, ok, err := kv.Get([]byte("k1"))
+	assert.True(t, string(val) == "v1" && ok && err == nil)
+
+	_, ok, err = kv.Get([]byte("xxx"))
+	assert.True(t, !ok && err == nil)
+
+	updated, err = kv.Del([]byte("xxx"))
+	assert.True(t, !updated && err == nil)
+
+	updated, err = kv.Del([]byte("k1"))
+	assert.True(t, updated && err == nil)
+
+	_, ok, err = kv.Get([]byte("xxx"))
+	assert.True(t, !ok && err == nil)
+
+	updated, err = kv.Set([]byte("k2"), []byte("v2"))
+	assert.True(t, updated && err == nil)
+
+	// reopen
+	kv.Close()
+	err = kv.Open()
+	assert.Nil(t, err)
+
+	_, ok, err = kv.Get([]byte("k1"))
+	assert.True(t, !ok && err == nil)
+	val, ok, err = kv.Get([]byte("k2"))
+	assert.True(t, string(val) == "v2" && ok && err == nil)
+}
+
+func TestKVUpdateMode(t *testing.T) {
+	kv := KV{}
+	kv.log.FileName = ".test_db"
+	defer os.Remove(kv.log.FileName)
+
+	os.Remove(kv.log.FileName)
+	err := kv.Open()
+	assert.Nil(t, err)
+	defer kv.Close()
+
+	updated, err := kv.SetEx([]byte("k1"), []byte("v1"), ModeUpdate)
+	assert.True(t, !updated && err == nil)
+
+	updated, err = kv.SetEx([]byte("k1"), []byte("v1"), ModeUpdate)
+	assert.True(t, !updated && err == nil)
+
+	updated, err = kv.SetEx([]byte("k1"), []byte("v1"), ModeInsert)
+	assert.True(t, updated && err == nil)
+
+	updated, err = kv.SetEx([]byte("k1"), []byte("xx"), ModeInsert)
+	assert.True(t, !updated && err == nil)
+
+	updated, err = kv.SetEx([]byte("k1"), []byte("yy"), ModeUpdate)
+	assert.True(t, updated && err == nil)
+
+	updated, err = kv.SetEx([]byte("k1"), []byte("zz"), ModeUpsert)
+	assert.True(t, updated && err == nil)
+
+	updated, err = kv.SetEx([]byte("k2"), []byte("tt"), ModeUpsert)
+	assert.True(t, updated && err == nil)
+}
+
+func TestKVRecovery(t *testing.T) {
+	kv := KV{}
+	kv.log.FileName = ".test_db"
+	defer os.Remove(kv.log.FileName)
+
+	prepare := func() {
+		os.Remove(kv.log.FileName)
+
+		err := kv.Open()
+		assert.Nil(t, err)
+		defer kv.Close()
+
+		updated, err := kv.Set([]byte("k1"), []byte("v1"))
+		assert.True(t, updated && err == nil)
+		updated, err = kv.Set([]byte("k2"), []byte("v2"))
+		assert.True(t, updated && err == nil)
+	}
+
+	prepare()
+	// simulate truncated log
+	fp, _ := os.OpenFile(kv.log.FileName, os.O_RDWR, 0o644)
+	st, _ := fp.Stat()
+	fp.Truncate(st.Size() - 1)
+	fp.Close()
+	// reopen
+	err := kv.Open()
+	assert.Nil(t, err)
+	// test
+	val, ok, err := kv.Get([]byte("k1"))
+	assert.True(t, string(val) == "v1" && ok && err == nil)
+	_, ok, err = kv.Get([]byte("k2")) // bad
+	assert.True(t, !ok && err == nil)
+	kv.Close()
+
+	prepare()
+	// simulate bad checksum
+	fp, _ = os.OpenFile(kv.log.FileName, os.O_RDWR, 0o644)
+	st, _ = fp.Stat()
+	fp.WriteAt([]byte{0}, st.Size()-1)
+	fp.Close()
+	// reopen
+	err = kv.Open()
+	assert.Nil(t, err)
+	// test
+	val, ok, err = kv.Get([]byte("k1"))
+	assert.True(t, string(val) == "v1" && ok && err == nil)
+	_, ok, err = kv.Get([]byte("k2")) // bad
+	assert.True(t, !ok && err == nil)
+	kv.Close()
+}
+
+func TestEntryEncode(t *testing.T) {
+	ent := Entry{key: []byte("k1"), val: []byte("xxx")}
+	data := []byte{0xe9, 0xec, 0x4d, 0x9e, 2, 0, 0, 0, 3, 0, 0, 0, 0, 'k', '1', 'x', 'x', 'x'}
+
+	assert.Equal(t, data, ent.Encode())
+
+	decoded := Entry{}
+	err := decoded.Decode(bytes.NewBuffer(data))
+	assert.Nil(t, err)
+	assert.Equal(t, ent, decoded)
+
+	ent = Entry{key: []byte("k1"), deleted: true}
+	data = []byte{0x4c, 0xd0, 0xfe, 0xe5, 2, 0, 0, 0, 0, 0, 0, 0, 1, 'k', '1'}
+
+	assert.Equal(t, data, ent.Encode())
+
+	decoded = Entry{}
+	err = decoded.Decode(bytes.NewBuffer(data))
+	assert.Nil(t, err)
+	assert.Equal(t, ent, decoded)
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/

0401/log.go

@@ -0,0 +1,40 @@
+package db0401
+
+import (
+	"io"
+	"os"
+)
+
+type Log struct {
+	FileName string
+	fp       *os.File
+}
+
+func (log *Log) Open() (err error) {
+	log.fp, err = createFileSync(log.FileName)
+	return err
+}
+
+func (log *Log) Close() error {
+	return log.fp.Close()
+}
+
+func (log *Log) Write(ent *Entry) error {
+	if _, err := log.fp.Write(ent.Encode()); err != nil {
+		return err
+	}
+	return log.fp.Sync() // fsync
+}
+
+func (log *Log) Read(ent *Entry) (eof bool, err error) {
+	err = ent.Decode(log.fp)
+	if err == io.EOF || err == io.ErrUnexpectedEOF || err == ErrBadSum {
+		return true, nil
+	} else if err != nil {
+		return false, err
+	} else {
+		return false, nil
+	}
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/

0401/os_other.go

@@ -0,0 +1,11 @@
+//go:build !unix
+
+package db0401
+
+import "os"
+
+func createFileSync(file string) (*os.File, error) {
+	return os.OpenFile(file, os.O_RDWR|os.O_CREATE, 0o644)
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/

0401/os_unix.go

@@ -0,0 +1,34 @@
+//go:build unix
+
+package db0401
+
+import (
+	"os"
+	"path"
+	"syscall"
+)
+
+// open or create a file and fsync the directory
+func createFileSync(file string) (*os.File, error) {
+	fp, err := os.OpenFile(file, os.O_RDWR|os.O_CREATE, 0o644)
+	if err != nil {
+		return nil, err
+	}
+	if err = syncDir(path.Base(file)); err != nil {
+		_ = fp.Close()
+		return nil, err
+	}
+	return fp, err
+}
+
+func syncDir(file string) error {
+	flags := os.O_RDONLY | syscall.O_DIRECTORY
+	dirfd, err := syscall.Open(path.Dir(file), flags, 0o644)
+	if err != nil {
+		return err
+	}
+	defer syscall.Close(dirfd)
+	return syscall.Fsync(dirfd)
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/

0401/row.go

@@ -0,0 +1,95 @@
+package db0401
+
+import (
+	"errors"
+	"slices"
+)
+
+type Schema struct {
+	Table string
+	Cols  []Column
+	PKey  []int // indexes of primary key columns
+}
+
+type Column struct {
+	Name string
+	Type CellType
+}
+
+type Row []Cell
+
+func (schema *Schema) NewRow() Row {
+	return make(Row, len(schema.Cols))
+}
+
+func (row Row) EncodeKey(schema *Schema) (key []byte) {
+	key = append(key, []byte(schema.Table)...)
+	key = append(key, 0x00)
+	check(len(row) == len(schema.Cols))
+	for idx, value := range row {
+		if slices.Contains(schema.PKey, idx) {
+			check(value.Type == schema.Cols[idx].Type)
+			key = row[idx].Encode(key)
+		}
+	}
+	return key
+}
+
+func (row Row) EncodeVal(schema *Schema) (val []byte) {
+	check(len(row) == len(schema.Cols))
+	for idx, value := range row {
+		if !slices.Contains(schema.PKey, idx) {
+			check(value.Type == schema.Cols[idx].Type)
+			val = row[idx].Encode(val)
+		}
+	}
+	return val
+}
+
+func (row Row) DecodeKey(schema *Schema, key []byte) (err error) {
+	check(len(row) == len(schema.Cols))
+
+	if len(key) < len(schema.Table)+1 {
+		return errors.New("bad key")
+	}
+	if string(key[:len(schema.Table)+1]) != schema.Table+"\x00" {
+		return errors.New("bad key")
+	}
+	key = key[len(schema.Table)+1:]
+
+	for idx, col := range schema.Cols {
+		if !slices.Contains(schema.PKey, idx) {
+			continue
+		}
+		row[idx] = Cell{Type: col.Type}
+		if key, err = row[idx].Decode(key); err != nil {
+			return err
+		}
+	}
+
+	if len(key) != 0 {
+		return errors.New("trailing garbage")
+	}
+	return nil
+}
+
+func (row Row) DecodeVal(schema *Schema, val []byte) (err error) {
+	check(len(row) == len(schema.Cols))
+
+	for idx, col := range schema.Cols {
+		if slices.Contains(schema.PKey, idx) {
+			continue
+		}
+		row[idx] = Cell{Type: col.Type}
+		if val, err = row[idx].Decode(val); err != nil {
+			return err
+		}
+	}
+
+	if len(val) != 0 {
+		return errors.New("trailing garbage")
+	}
+	return nil
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/

0401/row_test.go

@@ -0,0 +1,38 @@
+package db0401
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRowEncode(t *testing.T) {
+	schema := &Schema{
+		Table: "link",
+		Cols: []Column{
+			{Name: "time", Type: TypeI64},
+			{Name: "src", Type: TypeStr},
+			{Name: "dst", Type: TypeStr},
+		},
+		PKey: []int{1, 2}, // (src, dst)
+	}
+
+	row := Row{
+		Cell{Type: TypeI64, I64: 123},
+		Cell{Type: TypeStr, Str: []byte("a")},
+		Cell{Type: TypeStr, Str: []byte("b")},
+	}
+	key := []byte{'l', 'i', 'n', 'k', 0, 1, 0, 0, 0, 'a', 1, 0, 0, 0, 'b'}
+	val := []byte{123, 0, 0, 0, 0, 0, 0, 0}
+	assert.Equal(t, key, row.EncodeKey(schema))
+	assert.Equal(t, val, row.EncodeVal(schema))
+
+	decoded := schema.NewRow()
+	err := decoded.DecodeKey(schema, key)
+	assert.Nil(t, err)
+	err = decoded.DecodeVal(schema, val)
+	assert.Nil(t, err)
+	assert.Equal(t, row, decoded)
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/

0401/sql_parser.go

@@ -0,0 +1,392 @@
+package db0401
+
+import (
+	"errors"
+	"strconv"
+	"strings"
+)
+
+type Parser struct {
+	buf string
+	pos int
+}
+
+func NewParser(s string) Parser {
+	return Parser{buf: s, pos: 0}
+}
+
+type StmtSelect struct {
+	table string
+	cols  []string
+	keys  []NamedCell
+}
+
+type NamedCell struct {
+	column string
+	value  Cell
+}
+
+type StmtCreatTable struct {
+	table string
+	cols  []Column
+	pkey  []string
+}
+
+type StmtInsert struct {
+	table string
+	value []Cell
+}
+
+type StmtUpdate struct {
+	table string
+	keys  []NamedCell
+	value []NamedCell
+}
+
+type StmtDelete struct {
+	table string
+	keys  []NamedCell
+}
+
+func isSpace(ch byte) bool {
+	switch ch {
+	case '\t', '\n', '\v', '\f', '\r', ' ':
+		return true
+	}
+	return false
+}
+func isAlpha(ch byte) bool {
+	return 'a' <= (ch|32) && (ch|32) <= 'z'
+}
+func isDigit(ch byte) bool {
+	return '0' <= ch && ch <= '9'
+}
+func isNameStart(ch byte) bool {
+	return isAlpha(ch) || ch == '_'
+}
+func isNameContinue(ch byte) bool {
+	return isAlpha(ch) || isDigit(ch) || ch == '_'
+}
+func isSeparator(ch byte) bool {
+	return ch < 128 && !isNameContinue(ch)
+}
+
+func (p *Parser) skipSpaces() {
+	for p.pos < len(p.buf) && isSpace(p.buf[p.pos]) {
+		p.pos += 1
+	}
+}
+
+func (p *Parser) tryKeyword(kws ...string) bool {
+	save := p.pos
+	for _, kw := range kws {
+		p.skipSpaces()
+		if !(p.pos+len(kw) <= len(p.buf) && strings.EqualFold(p.buf[p.pos:p.pos+len(kw)], kw)) {
+			p.pos = save
+			return false
+		}
+		if p.pos+len(kw) < len(p.buf) && !isSeparator(p.buf[p.pos+len(kw)]) {
+			p.pos = save
+			return false
+		}
+		p.pos += len(kw)
+	}
+	return true
+}
+
+func (p *Parser) tryPunctuation(tok string) bool {
+	p.skipSpaces()
+	if !(p.pos+len(tok) <= len(p.buf) && p.buf[p.pos:p.pos+len(tok)] == tok) {
+		return false
+	}
+	p.pos += len(tok)
+	return true
+}
+
+func (p *Parser) tryName() (string, bool) {
+	p.skipSpaces()
+	start, cur := p.pos, p.pos
+	if !(cur < len(p.buf) && isNameStart(p.buf[cur])) {
+		return "", false
+	}
+	cur++
+	for cur < len(p.buf) && isNameContinue(p.buf[cur]) {
+		cur++
+	}
+	p.pos = cur
+	return p.buf[start:cur], true
+}
+
+func (p *Parser) parseValue(out *Cell) error {
+	p.skipSpaces()
+	if p.pos >= len(p.buf) {
+		return errors.New("expect value")
+	}
+	ch := p.buf[p.pos]
+	if ch == '"' || ch == '\'' {
+		return p.parseString(out)
+	} else if isDigit(ch) || ch == '-' || ch == '+' {
+		return p.parseInt(out)
+	} else {
+		return errors.New("expect value")
+	}
+}
+
+func (p *Parser) parseString(out *Cell) error {
+	quote := p.buf[p.pos]
+	cur := p.pos + 1
+	for cur < len(p.buf) {
+		ch := p.buf[cur]
+		if ch == '\\' {
+			cur++
+			if cur < len(p.buf) && (p.buf[cur] == '"' || p.buf[cur] == '\'') {
+				out.Str = append(out.Str, p.buf[cur])
+				cur++
+			} else {
+				return errors.New("bad escape")
+			}
+		} else if ch == quote {
+			out.Type = TypeStr
+			p.pos = cur + 1
+			return nil
+		} else {
+			out.Str = append(out.Str, p.buf[cur])
+			cur++
+		}
+	}
+	return errors.New("string is not terminated")
+}
+
+func (p *Parser) parseInt(out *Cell) (err error) {
+	start, cur := p.pos, p.pos
+	if p.buf[cur] == '-' || p.buf[cur] == '+' {
+		cur++
+	}
+	for cur < len(p.buf) && isDigit(p.buf[cur]) {
+		cur++
+	}
+
+	if out.I64, err = strconv.ParseInt(p.buf[start:cur], 10, 64); err != nil {
+		return err
+	}
+	out.Type = TypeI64
+	p.pos = cur
+	return nil
+}
+
+func (p *Parser) parseEqual(out *NamedCell) error {
+	var ok bool
+	out.column, ok = p.tryName()
+	if !ok {
+		return errors.New("expect column")
+	}
+	if !p.tryPunctuation("=") {
+		return errors.New("expect =")
+	}
+	return p.parseValue(&out.value)
+}
+
+func (p *Parser) parseSelect(out *StmtSelect) error {
+	for !p.tryKeyword("FROM") {
+		if len(out.cols) > 0 && !p.tryPunctuation(",") {
+			return errors.New("expect comma")
+		}
+		if name, ok := p.tryName(); ok {
+			out.cols = append(out.cols, name)
+		} else {
+			return errors.New("expect column")
+		}
+	}
+	if len(out.cols) == 0 {
+		return errors.New("expect column list")
+	}
+	var ok bool
+	if out.table, ok = p.tryName(); !ok {
+		return errors.New("expect table name")
+	}
+	return p.parseWhere(&out.keys)
+}
+
+func (p *Parser) parseWhere(out *[]NamedCell) error {
+	if !p.tryKeyword("WHERE") {
+		return errors.New("expect keyword")
+	}
+	for !p.tryPunctuation(";") {
+		expr := NamedCell{}
+		if len(*out) > 0 && !p.tryKeyword("AND") {
+			return errors.New("expect AND")
+		}
+		if err := p.parseEqual(&expr); err != nil {
+			return err
+		}
+		*out = append(*out, expr)
+	}
+	if len(*out) == 0 {
+		return errors.New("expect where clause")
+	}
+	return nil
+}
+
+func (p *Parser) parseCommaList(item func() error) error {
+	if !p.tryPunctuation("(") {
+		return errors.New("expect (")
+	}
+	comma := false
+	for !p.tryPunctuation(")") {
+		if comma && !p.tryPunctuation(",") {
+			return errors.New("expect ,")
+		}
+		comma = true
+		if err := item(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (p *Parser) parseNameItem(out *[]string) error {
+	name, ok := p.tryName()
+	if !ok {
+		return errors.New("expect name")
+	}
+	*out = append(*out, name)
+	return nil
+}
+
+func (p *Parser) parseCreateTableItem(out *StmtCreatTable) error {
+	if p.tryKeyword("PRIMARY", "KEY") {
+		return p.parseCommaList(func() error { return p.parseNameItem(&out.pkey) })
+	}
+
+	var ok bool
+	col := Column{}
+	if col.Name, ok = p.tryName(); !ok {
+		return errors.New("expect name")
+	}
+	kind, ok := p.tryName()
+	if !ok {
+		return errors.New("expect name")
+	}
+	switch kind {
+	case "int64":
+		col.Type = TypeI64
+	case "string":
+		col.Type = TypeStr
+	default:
+		return errors.New("unknown column type")
+	}
+	out.cols = append(out.cols, col)
+	return nil
+}
+
+func (p *Parser) parseCreateTable(out *StmtCreatTable) error {
+	var ok bool
+	if out.table, ok = p.tryName(); !ok {
+		return errors.New("expect table name")
+	}
+	err := p.parseCommaList(func() error { return p.parseCreateTableItem(out) })
+	if err != nil {
+		return err
+	}
+	if !p.tryPunctuation(";") {
+		return errors.New("expect ;")
+	}
+	return nil
+}
+
+func (p *Parser) parseValueItem(out *[]Cell) error {
+	cell := Cell{}
+	if err := p.parseValue(&cell); err != nil {
+		return err
+	}
+	*out = append(*out, cell)
+	return nil
+}
+
+func (p *Parser) parseInsert(out *StmtInsert) error {
+	var ok bool
+	if out.table, ok = p.tryName(); !ok {
+		return errors.New("expect table name")
+	}
+	if !p.tryKeyword("VALUES") {
+		return errors.New("expect VALUES")
+	}
+	err := p.parseCommaList(func() error { return p.parseValueItem(&out.value) })
+	if err != nil {
+		return err
+	}
+	if !p.tryPunctuation(";") {
+		return errors.New("expect ;")
+	}
+	return nil
+}
+
+func (p *Parser) parseUpdate(out *StmtUpdate) error {
+	var ok bool
+	if out.table, ok = p.tryName(); !ok {
+		return errors.New("expect table name")
+	}
+	if !p.tryKeyword("SET") {
+		return errors.New("expect SET")
+	}
+	for !p.tryKeyword("WHERE") {
+		expr := NamedCell{}
+		if len(out.value) > 0 && !p.tryKeyword(",") {
+			return errors.New("expect ,")
+		}
+		if err := p.parseEqual(&expr); err != nil {
+			return err
+		}
+		out.value = append(out.value, expr)
+	}
+	if len(out.value) == 0 {
+		return errors.New("expect assignment list")
+	}
+	p.pos -= len("WHERE")
+	return p.parseWhere(&out.keys)
+}
+
+func (p *Parser) parseDelete(out *StmtDelete) error {
+	var ok bool
+	if out.table, ok = p.tryName(); !ok {
+		return errors.New("expect table name")
+	}
+	return p.parseWhere(&out.keys)
+}
+
+func (p *Parser) parseStmt() (out interface{}, err error) {
+	if p.tryKeyword("SELECT") {
+		stmt := &StmtSelect{}
+		err = p.parseSelect(stmt)
+		out = stmt
+	} else if p.tryKeyword("CREATE", "TABLE") {
+		stmt := &StmtCreatTable{}
+		err = p.parseCreateTable(stmt)
+		out = stmt
+	} else if p.tryKeyword("INSERT", "INTO") {
+		stmt := &StmtInsert{}
+		err = p.parseInsert(stmt)
+		out = stmt
+	} else if p.tryKeyword("UPDATE") {
+		stmt := &StmtUpdate{}
+		err = p.parseUpdate(stmt)
+		out = stmt
+	} else if p.tryKeyword("DELETE", "FROM") {
+		stmt := &StmtDelete{}
+		err = p.parseDelete(stmt)
+		out = stmt
+	} else {
+		err = errors.New("unknown statement")
+	}
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (p *Parser) isEnd() bool {
+	p.skipSpaces()
+	return p.pos >= len(p.buf)
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/

0401/sql_parser_test.go

@@ -0,0 +1,110 @@
+package db0401
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestParseName(t *testing.T) {
+	p := NewParser(" a b0 _0_ 123 ")
+	name, ok := p.tryName()
+	assert.True(t, ok && name == "a")
+	name, ok = p.tryName()
+	assert.True(t, ok && name == "b0")
+	name, ok = p.tryName()
+	assert.True(t, ok && name == "_0_")
+	_, ok = p.tryName()
+	assert.False(t, ok)
+}
+
+func TestParseKeyword(t *testing.T) {
+	p := NewParser(" select  HELLO ")
+	assert.False(t, p.tryKeyword("sel"))
+	assert.True(t, p.tryKeyword("SELECT"))
+	assert.True(t, p.tryKeyword("hello") && p.isEnd())
+
+	p = NewParser(" select  HELLO ")
+	assert.False(t, p.tryKeyword("select", "hi"))
+	assert.True(t, p.tryKeyword("select", "hello") && p.isEnd())
+}
+
+func testParseValue(t *testing.T, s string, ref Cell) {
+	p := NewParser(s)
+	out := Cell{}
+	err := p.parseValue(&out)
+	assert.Nil(t, err)
+	assert.True(t, p.isEnd())
+	assert.Equal(t, ref, out)
+}
+
+func TestParseValue(t *testing.T) {
+	testParseValue(t, " -123 ", Cell{Type: TypeI64, I64: -123})
+	testParseValue(t, ` 'abc\'\"d' `, Cell{Type: TypeStr, Str: []byte("abc'\"d")})
+	testParseValue(t, ` "abc\'\"d" `, Cell{Type: TypeStr, Str: []byte("abc'\"d")})
+}
+
+func testParseStmt(t *testing.T, s string, ref interface{}) {
+	p := NewParser(s)
+	out, err := p.parseStmt()
+	assert.Nil(t, err)
+	assert.True(t, p.isEnd())
+	assert.Equal(t, ref, out)
+}
+
+func TestParseStmt(t *testing.T) {
+	var stmt interface{}
+	s := "select a from t where c=1;"
+	stmt = &StmtSelect{
+		table: "t",
+		cols:  []string{"a"},
+		keys:  []NamedCell{{column: "c", value: Cell{Type: TypeI64, I64: 1}}},
+	}
+	testParseStmt(t, s, stmt)
+
+	s = "select a,b_02 from T where c=1 and d='e';"
+	stmt = &StmtSelect{
+		table: "T",
+		cols:  []string{"a", "b_02"},
+		keys: []NamedCell{
+			{column: "c", value: Cell{Type: TypeI64, I64: 1}},
+			{column: "d", value: Cell{Type: TypeStr, Str: []byte("e")}},
+		},
+	}
+	testParseStmt(t, s, stmt)
+
+	s = "select a, b_02 from T where c = 1 and d = 'e' ; "
+	testParseStmt(t, s, stmt)
+
+	s = "create table t (a string, b int64, primary key (b));"
+	stmt = &StmtCreatTable{
+		table: "t",
+		cols:  []Column{{"a", TypeStr}, {"b", TypeI64}},
+		pkey:  []string{"b"},
+	}
+	testParseStmt(t, s, stmt)
+
+	s = "insert into t values (1, 'hi');"
+	stmt = &StmtInsert{
+		table: "t",
+		value: []Cell{{Type: TypeI64, I64: 1}, {Type: TypeStr, Str: []byte("hi")}},
+	}
+	testParseStmt(t, s, stmt)
+
+	s = "update t set a = 1, b = 2 where c = 3 and d = 4;"
+	stmt = &StmtUpdate{
+		table: "t",
+		value: []NamedCell{{"a", Cell{Type: TypeI64, I64: 1}}, {"b", Cell{Type: TypeI64, I64: 2}}},
+		keys:  []NamedCell{{"c", Cell{Type: TypeI64, I64: 3}}, {"d", Cell{Type: TypeI64, I64: 4}}},
+	}
+	testParseStmt(t, s, stmt)
+
+	s = "delete from t where c = 3 and d = 4;"
+	stmt = &StmtDelete{
+		table: "t",
+		keys:  []NamedCell{{"c", Cell{Type: TypeI64, I64: 3}}, {"d", Cell{Type: TypeI64, I64: 4}}},
+	}
+	testParseStmt(t, s, stmt)
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/

0401/table.go

@@ -0,0 +1,267 @@
+package db0401
+
+import (
+	"encoding/json"
+	"errors"
+	"slices"
+)
+
+type DB struct {
+	KV     KV
+	tables map[string]Schema
+}
+
+func (db *DB) Open() error {
+	db.tables = map[string]Schema{}
+	return db.KV.Open()
+}
+
+func (db *DB) Close() error { return db.KV.Close() }
+
+func (db *DB) Select(schema *Schema, row Row) (ok bool, err error) {
+	key := row.EncodeKey(schema)
+	val, ok, err := db.KV.Get(key)
+	if err != nil || !ok {
+		return ok, err
+	}
+	if err = row.DecodeVal(schema, val); err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
+func (db *DB) Insert(schema *Schema, row Row) (updated bool, err error) {
+	key := row.EncodeKey(schema)
+	val := row.EncodeVal(schema)
+	return db.KV.SetEx(key, val, ModeInsert)
+}
+
+func (db *DB) Upsert(schema *Schema, row Row) (updated bool, err error) {
+	key := row.EncodeKey(schema)
+	val := row.EncodeVal(schema)
+	return db.KV.SetEx(key, val, ModeUpsert)
+}
+
+func (db *DB) Update(schema *Schema, row Row) (updated bool, err error) {
+	key := row.EncodeKey(schema)
+	val := row.EncodeVal(schema)
+	return db.KV.SetEx(key, val, ModeUpdate)
+}
+
+func (db *DB) Delete(schema *Schema, row Row) (deleted bool, err error) {
+	key := row.EncodeKey(schema)
+	return db.KV.Del(key)
+}
+
+type SQLResult struct {
+	Updated int
+	Header  []string
+	Values  []Row
+}
+
+func (db *DB) ExecStmt(stmt interface{}) (r SQLResult, err error) {
+	switch ptr := stmt.(type) {
+	case *StmtCreatTable:
+		err = db.execCreateTable(ptr)
+	case *StmtSelect:
+		r.Header = ptr.cols
+		r.Values, err = db.execSelect(ptr)
+	case *StmtInsert:
+		r.Updated, err = db.execInsert(ptr)
+	case *StmtUpdate:
+		r.Updated, err = db.execUpdate(ptr)
+	case *StmtDelete:
+		r.Updated, err = db.execDelete(ptr)
+	default:
+		panic("unreachable")
+	}
+	return
+}
+
+func (db *DB) execCreateTable(stmt *StmtCreatTable) (err error) {
+	if _, err := db.GetSchema(stmt.table); err == nil {
+		return errors.New("duplicate table name")
+	}
+
+	schema := Schema{
+		Table: stmt.table,
+		Cols:  stmt.cols,
+	}
+	if schema.PKey, err = lookupColumns(stmt.cols, stmt.pkey); err != nil {
+		return err
+	}
+
+	val, err := json.Marshal(schema)
+	check(err == nil)
+	if _, err = db.KV.Set([]byte("@schema_"+stmt.table), val); err != nil {
+		return err
+	}
+
+	db.tables[schema.Table] = schema
+	return nil
+}
+
+func (db *DB) GetSchema(table string) (Schema, error) {
+	schema, ok := db.tables[table]
+	if !ok {
+		val, ok, err := db.KV.Get([]byte("@schema_" + table))
+		if err == nil && ok {
+			err = json.Unmarshal(val, &schema)
+		}
+		if err != nil {
+			return Schema{}, err
+		}
+		if !ok {
+			return Schema{}, errors.New("table is not found")
+		}
+		db.tables[table] = schema
+	}
+	return schema, nil
+}
+
+func lookupColumns(cols []Column, names []string) (indices []int, err error) {
+	for _, name := range names {
+		idx := slices.IndexFunc(cols, func(col Column) bool {
+			return col.Name == name
+		})
+		if idx < 0 {
+			return nil, errors.New("column is not found")
+		}
+		indices = append(indices, idx)
+	}
+	return
+}
+
+func makePKey(schema *Schema, pkey []NamedCell) (Row, error) {
+	if len(schema.PKey) != len(pkey) {
+		return nil, errors.New("not primary key")
+	}
+	row := schema.NewRow()
+	for _, idx1 := range schema.PKey {
+		col := schema.Cols[idx1]
+		idx2 := slices.IndexFunc(pkey, func(expr NamedCell) bool {
+			return expr.column == col.Name && expr.value.Type == col.Type
+		})
+		if idx2 < 0 {
+			return nil, errors.New("not primary key")
+		}
+		row[idx1] = pkey[idx2].value
+	}
+	return row, nil
+}
+
+func subsetRow(row Row, indices []int) (out Row) {
+	for _, idx := range indices {
+		out = append(out, row[idx])
+	}
+	return
+}
+
+func (db *DB) execSelect(stmt *StmtSelect) ([]Row, error) {
+	schema, err := db.GetSchema(stmt.table)
+	if err != nil {
+		return nil, err
+	}
+	indices, err := lookupColumns(schema.Cols, stmt.cols)
+	if err != nil {
+		return nil, err
+	}
+
+	row, err := makePKey(&schema, stmt.keys)
+	if err != nil {
+		return nil, err
+	}
+	if ok, err := db.Select(&schema, row); err != nil || !ok {
+		return nil, err
+	}
+
+	row = subsetRow(row, indices)
+	return []Row{row}, nil
+}
+
+func (db *DB) execInsert(stmt *StmtInsert) (count int, err error) {
+	schema, err := db.GetSchema(stmt.table)
+	if err != nil {
+		return 0, err
+	}
+	if len(schema.Cols) != len(stmt.value) {
+		return 0, errors.New("schema mismatch")
+	}
+	for i := range schema.Cols {
+		if schema.Cols[i].Type != stmt.value[i].Type {
+			return 0, errors.New("schema mismatch")
+		}
+	}
+
+	updated, err := db.Insert(&schema, stmt.value)
+	if err != nil {
+		return 0, err
+	}
+	if updated {
+		count++
+	}
+	return count, nil
+}
+
+func fillNonPKey(schema *Schema, updates []NamedCell, out Row) error {
+	for _, expr := range updates {
+		idx := slices.IndexFunc(schema.Cols, func(col Column) bool {
+			return col.Name == expr.column && col.Type == expr.value.Type
+		})
+		if idx < 0 || slices.Contains(schema.PKey, idx) {
+			return errors.New("cannot update column")
+		}
+		out[idx] = expr.value
+	}
+	return nil
+}
+
+func (db *DB) execUpdate(stmt *StmtUpdate) (count int, err error) {
+	schema, err := db.GetSchema(stmt.table)
+	if err != nil {
+		return 0, err
+	}
+
+	row, err := makePKey(&schema, stmt.keys)
+	if err != nil {
+		return 0, err
+	}
+	if ok, err := db.Select(&schema, row); err != nil || !ok {
+		return 0, err
+	}
+
+	if err = fillNonPKey(&schema, stmt.value, row); err != nil {
+		return 0, err
+	}
+	updated, err := db.Update(&schema, row)
+	if err != nil {
+		return 0, err
+	}
+	if updated {
+		count++
+	}
+	return count, nil
+}
+
+func (db *DB) execDelete(stmt *StmtDelete) (count int, err error) {
+	schema, err := db.GetSchema(stmt.table)
+	if err != nil {
+		return 0, err
+	}
+
+	row, err := makePKey(&schema, stmt.keys)
+	if err != nil {
+		return 0, err
+	}
+
+	updated, err := db.Delete(&schema, row)
+	if err != nil {
+		return 0, err
+	}
+	if updated {
+		count++
+	}
+	return count, nil
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/

0401/table_test.go

@@ -0,0 +1,126 @@
+package db0401
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestTableByPKey(t *testing.T) {
+	db := DB{}
+	db.KV.log.FileName = ".test_db"
+	defer os.Remove(db.KV.log.FileName)
+
+	os.Remove(db.KV.log.FileName)
+	err := db.Open()
+	assert.Nil(t, err)
+	defer db.Close()
+
+	schema := &Schema{
+		Table: "link",
+		Cols: []Column{
+			{Name: "time", Type: TypeI64},
+			{Name: "src", Type: TypeStr},
+			{Name: "dst", Type: TypeStr},
+		},
+		PKey: []int{1, 2}, // (src, dst)
+	}
+
+	row := Row{
+		Cell{Type: TypeI64, I64: 123},
+		Cell{Type: TypeStr, Str: []byte("a")},
+		Cell{Type: TypeStr, Str: []byte("b")},
+	}
+	ok, err := db.Select(schema, row)
+	assert.True(t, !ok && err == nil)
+
+	updated, err := db.Insert(schema, row)
+	assert.True(t, updated && err == nil)
+
+	out := Row{
+		Cell{},
+		Cell{Type: TypeStr, Str: []byte("a")},
+		Cell{Type: TypeStr, Str: []byte("b")},
+	}
+	ok, err = db.Select(schema, out)
+	assert.True(t, ok && err == nil)
+	assert.Equal(t, row, out)
+
+	row[0].I64 = 456
+	updated, err = db.Update(schema, row)
+	assert.True(t, updated && err == nil)
+
+	ok, err = db.Select(schema, out)
+	assert.True(t, ok && err == nil)
+	assert.Equal(t, row, out)
+
+	deleted, err := db.Delete(schema, row)
+	assert.True(t, deleted && err == nil)
+
+	ok, err = db.Select(schema, row)
+	assert.True(t, !ok && err == nil)
+}
+
+func parseStmt(t *testing.T, s string) interface{} {
+	p := NewParser(s)
+	stmt, err := p.parseStmt()
+	require.Nil(t, err)
+	return stmt
+}
+
+func TestSQLByPKey(t *testing.T) {
+	db := DB{}
+	db.KV.log.FileName = ".test_db"
+	defer os.Remove(db.KV.log.FileName)
+
+	os.Remove(db.KV.log.FileName)
+	err := db.Open()
+	assert.Nil(t, err)
+	defer db.Close()
+
+	s := "create table link (time int64, src string, dst string, primary key (src, dst));"
+	_, err = db.ExecStmt(parseStmt(t, s))
+	require.Nil(t, err)
+
+	s = "insert into link values (123, 'bob', 'alice');"
+	r, err := db.ExecStmt(parseStmt(t, s))
+	require.Nil(t, err)
+	require.Equal(t, 1, r.Updated)
+
+	s = "select time from link where dst = 'alice' and src = 'bob';"
+	r, err = db.ExecStmt(parseStmt(t, s))
+	require.Nil(t, err)
+	require.Equal(t, []Row{{Cell{Type: TypeI64, I64: 123}}}, r.Values)
+
+	s = "update link set time = 456 where dst = 'alice' and src = 'bob';"
+	r, err = db.ExecStmt(parseStmt(t, s))
+	require.Nil(t, err)
+	require.Equal(t, 1, r.Updated)
+
+	s = "select time from link where dst = 'alice' and src = 'bob';"
+	r, err = db.ExecStmt(parseStmt(t, s))
+	require.Nil(t, err)
+	require.Equal(t, []Row{{Cell{Type: TypeI64, I64: 456}}}, r.Values)
+
+	// reopen
+	err = db.Close()
+	require.Nil(t, err)
+	db = DB{}
+	db.KV.log.FileName = ".test_db"
+	err = db.Open()
+	require.Nil(t, err)
+
+	s = "delete from link where src = 'bob' and dst = 'alice';"
+	r, err = db.ExecStmt(parseStmt(t, s))
+	require.Nil(t, err)
+	require.Equal(t, 1, r.Updated)
+
+	s = "select time from link where dst = 'alice' and src = 'bob';"
+	r, err = db.ExecStmt(parseStmt(t, s))
+	require.Nil(t, err)
+	require.Equal(t, 0, len(r.Values))
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/