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package sql3util
import (
"context"
_ "embed"
"sync"
"github.com/tetratelabs/wazero"
"github.com/tetratelabs/wazero/api"
"github.com/ncruces/go-sqlite3/internal/util"
)
const (
errp = 4
sqlp = 8
)
var (
//go:embed wasm/sql3parse_table.wasm
binary []byte
once sync.Once
runtime wazero.Runtime
compiled wazero.CompiledModule
)
// ParseTable parses a [CREATE] or [ALTER TABLE] command.
//
// [CREATE]: https://sqlite.org/lang_createtable.html
// [ALTER TABLE]: https://sqlite.org/lang_altertable.html
func ParseTable(sql string) (_ *Table, err error) {
once.Do(func() {
ctx := context.Background()
cfg := wazero.NewRuntimeConfigInterpreter()
runtime = wazero.NewRuntimeWithConfig(ctx, cfg)
compiled, err = runtime.CompileModule(ctx, binary)
})
if err != nil {
return nil, err
}
ctx := context.Background()
mod, err := runtime.InstantiateModule(ctx, compiled, wazero.NewModuleConfig().WithName(""))
if err != nil {
return nil, err
}
defer mod.Close(ctx)
if buf, ok := mod.Memory().Read(sqlp, uint32(len(sql))); ok {
copy(buf, sql)
}
stack := [...]uint64{sqlp, uint64(len(sql)), errp}
err = mod.ExportedFunction("sql3parse_table").CallWithStack(ctx, stack[:])
if err != nil {
return nil, err
}
c, _ := mod.Memory().ReadUint32Le(errp)
switch c {
case _MEMORY:
panic(util.OOMErr)
case _SYNTAX:
return nil, util.ErrorString("sql3parse: invalid syntax")
case _UNSUPPORTEDSQL:
return nil, util.ErrorString("sql3parse: unsupported SQL")
}
var tab Table
tab.load(mod, uint32(stack[0]), sql)
return &tab, nil
}
// Table holds metadata about a table.
type Table struct {
Name string
Schema string
Comment string
IsTemporary bool
IsIfNotExists bool
IsWithoutRowID bool
IsStrict bool
Columns []Column
Type StatementType
CurrentName string
NewName string
}
func (t *Table) load(mod api.Module, ptr uint32, sql string) {
t.Name = loadString(mod, ptr+0, sql)
t.Schema = loadString(mod, ptr+8, sql)
t.Comment = loadString(mod, ptr+16, sql)
t.IsTemporary = loadBool(mod, ptr+24)
t.IsIfNotExists = loadBool(mod, ptr+25)
t.IsWithoutRowID = loadBool(mod, ptr+26)
t.IsStrict = loadBool(mod, ptr+27)
t.Columns = loadSlice(mod, ptr+28, func(ptr uint32, res *Column) {
p, _ := mod.Memory().ReadUint32Le(ptr)
res.load(mod, p, sql)
})
t.Type = loadEnum[StatementType](mod, ptr+44)
t.CurrentName = loadString(mod, ptr+48, sql)
t.NewName = loadString(mod, ptr+56, sql)
}
// Column holds metadata about a column.
type Column struct {
Name string
Type string
Length string
ConstraintName string
Comment string
IsPrimaryKey bool
IsAutoIncrement bool
IsNotNull bool
IsUnique bool
PKOrder OrderClause
PKConflictClause ConflictClause
NotNullConflictClause ConflictClause
UniqueConflictClause ConflictClause
CheckExpr string
DefaultExpr string
CollateName string
ForeignKeyClause *ForeignKey
}
func (c *Column) load(mod api.Module, ptr uint32, sql string) {
c.Name = loadString(mod, ptr+0, sql)
c.Type = loadString(mod, ptr+8, sql)
c.Length = loadString(mod, ptr+16, sql)
c.ConstraintName = loadString(mod, ptr+24, sql)
c.Comment = loadString(mod, ptr+32, sql)
c.IsPrimaryKey = loadBool(mod, ptr+40)
c.IsAutoIncrement = loadBool(mod, ptr+41)
c.IsNotNull = loadBool(mod, ptr+42)
c.IsUnique = loadBool(mod, ptr+43)
c.PKOrder = loadEnum[OrderClause](mod, ptr+44)
c.PKConflictClause = loadEnum[ConflictClause](mod, ptr+48)
c.NotNullConflictClause = loadEnum[ConflictClause](mod, ptr+52)
c.UniqueConflictClause = loadEnum[ConflictClause](mod, ptr+56)
c.CheckExpr = loadString(mod, ptr+60, sql)
c.DefaultExpr = loadString(mod, ptr+68, sql)
c.CollateName = loadString(mod, ptr+76, sql)
if ptr, _ := mod.Memory().ReadUint32Le(ptr + 84); ptr != 0 {
c.ForeignKeyClause = &ForeignKey{}
c.ForeignKeyClause.load(mod, ptr, sql)
}
}
type ForeignKey struct {
Table string
Columns []string
OnDelete FKAction
OnUpdate FKAction
Match string
Deferrable FKDefType
}
func (f *ForeignKey) load(mod api.Module, ptr uint32, sql string) {
f.Table = loadString(mod, ptr+0, sql)
f.Columns = loadSlice(mod, ptr+8, func(ptr uint32, res *string) {
*res = loadString(mod, ptr, sql)
})
f.OnDelete = loadEnum[FKAction](mod, ptr+16)
f.OnUpdate = loadEnum[FKAction](mod, ptr+20)
f.Match = loadString(mod, ptr+24, sql)
f.Deferrable = loadEnum[FKDefType](mod, ptr+32)
}
func loadString(mod api.Module, ptr uint32, sql string) string {
off, _ := mod.Memory().ReadUint32Le(ptr + 0)
if off == 0 {
return ""
}
len, _ := mod.Memory().ReadUint32Le(ptr + 4)
return sql[off-sqlp : off+len-sqlp]
}
func loadSlice[T any](mod api.Module, ptr uint32, fn func(uint32, *T)) []T {
ref, _ := mod.Memory().ReadUint32Le(ptr + 4)
if ref == 0 {
return nil
}
len, _ := mod.Memory().ReadUint32Le(ptr + 0)
res := make([]T, len)
for i := range res {
fn(ref, &res[i])
ref += 4
}
return res
}
func loadEnum[T ~uint32](mod api.Module, ptr uint32) T {
val, _ := mod.Memory().ReadUint32Le(ptr)
return T(val)
}
func loadBool(mod api.Module, ptr uint32) bool {
val, _ := mod.Memory().ReadByte(ptr)
return val != 0
}
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