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			233 lines
		
	
	
	
		
			7.1 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			233 lines
		
	
	
	
		
			7.1 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
package sqlite3
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import (
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	"context"
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	"sync"
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	"github.com/tetratelabs/wazero/api"
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	"github.com/ncruces/go-sqlite3/internal/util"
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)
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// CollationNeeded registers a callback to be invoked
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// whenever an unknown collation sequence is required.
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//
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// https://sqlite.org/c3ref/collation_needed.html
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func (c *Conn) CollationNeeded(cb func(db *Conn, name string)) error {
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	var enable int32
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	if cb != nil {
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		enable = 1
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	}
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	rc := res_t(c.call("sqlite3_collation_needed_go", stk_t(c.handle), stk_t(enable)))
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	if err := c.error(rc); err != nil {
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		return err
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	}
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	c.collation = cb
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	return nil
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}
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// AnyCollationNeeded uses [Conn.CollationNeeded] to register
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// a fake collating function for any unknown collating sequence.
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// The fake collating function works like BINARY.
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//
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// This can be used to load schemas that contain
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// one or more unknown collating sequences.
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func (c Conn) AnyCollationNeeded() error {
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	rc := res_t(c.call("sqlite3_anycollseq_init", stk_t(c.handle), 0, 0))
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	if err := c.error(rc); err != nil {
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		return err
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	}
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	c.collation = nil
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	return nil
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}
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// CreateCollation defines a new collating sequence.
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//
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// https://sqlite.org/c3ref/create_collation.html
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func (c *Conn) CreateCollation(name string, fn func(a, b []byte) int) error {
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	var funcPtr ptr_t
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	defer c.arena.mark()()
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	namePtr := c.arena.string(name)
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	if fn != nil {
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		funcPtr = util.AddHandle(c.ctx, fn)
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	}
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	rc := res_t(c.call("sqlite3_create_collation_go",
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		stk_t(c.handle), stk_t(namePtr), stk_t(funcPtr)))
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	return c.error(rc)
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}
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// CreateFunction defines a new scalar SQL function.
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//
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// https://sqlite.org/c3ref/create_function.html
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func (c *Conn) CreateFunction(name string, nArg int, flag FunctionFlag, fn ScalarFunction) error {
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	var funcPtr ptr_t
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	defer c.arena.mark()()
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	namePtr := c.arena.string(name)
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	if fn != nil {
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		funcPtr = util.AddHandle(c.ctx, fn)
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	}
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	rc := res_t(c.call("sqlite3_create_function_go",
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		stk_t(c.handle), stk_t(namePtr), stk_t(nArg),
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		stk_t(flag), stk_t(funcPtr)))
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	return c.error(rc)
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}
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// ScalarFunction is the type of a scalar SQL function.
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// Implementations must not retain arg.
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type ScalarFunction func(ctx Context, arg ...Value)
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// CreateWindowFunction defines a new aggregate or aggregate window SQL function.
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// If fn returns a [WindowFunction], then an aggregate window function is created.
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// If fn returns an [io.Closer], it will be called to free resources.
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//
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// https://sqlite.org/c3ref/create_function.html
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func (c *Conn) CreateWindowFunction(name string, nArg int, flag FunctionFlag, fn func() AggregateFunction) error {
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	var funcPtr ptr_t
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	defer c.arena.mark()()
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	namePtr := c.arena.string(name)
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	if fn != nil {
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		funcPtr = util.AddHandle(c.ctx, fn)
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	}
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	call := "sqlite3_create_aggregate_function_go"
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	if _, ok := fn().(WindowFunction); ok {
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		call = "sqlite3_create_window_function_go"
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	}
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	rc := res_t(c.call(call,
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		stk_t(c.handle), stk_t(namePtr), stk_t(nArg),
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		stk_t(flag), stk_t(funcPtr)))
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	return c.error(rc)
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}
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// AggregateFunction is the interface an aggregate function should implement.
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//
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// https://sqlite.org/appfunc.html
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type AggregateFunction interface {
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	// Step is invoked to add a row to the current window.
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	// The function arguments, if any, corresponding to the row being added, are passed to Step.
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	// Implementations must not retain arg.
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	Step(ctx Context, arg ...Value)
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	// Value is invoked to return the current (or final) value of the aggregate.
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	Value(ctx Context)
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}
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// WindowFunction is the interface an aggregate window function should implement.
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//
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// https://sqlite.org/windowfunctions.html
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type WindowFunction interface {
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	AggregateFunction
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	// Inverse is invoked to remove the oldest presently aggregated result of Step from the current window.
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	// The function arguments, if any, are those passed to Step for the row being removed.
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	// Implementations must not retain arg.
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	Inverse(ctx Context, arg ...Value)
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}
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// OverloadFunction overloads a function for a virtual table.
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//
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// https://sqlite.org/c3ref/overload_function.html
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func (c *Conn) OverloadFunction(name string, nArg int) error {
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	defer c.arena.mark()()
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	namePtr := c.arena.string(name)
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	rc := res_t(c.call("sqlite3_overload_function",
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		stk_t(c.handle), stk_t(namePtr), stk_t(nArg)))
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	return c.error(rc)
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}
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func destroyCallback(ctx context.Context, mod api.Module, pApp ptr_t) {
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	util.DelHandle(ctx, pApp)
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}
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func collationCallback(ctx context.Context, mod api.Module, pArg, pDB ptr_t, eTextRep uint32, zName ptr_t) {
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	if c, ok := ctx.Value(connKey{}).(*Conn); ok && c.handle == pDB && c.collation != nil {
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		name := util.ReadString(mod, zName, _MAX_NAME)
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		c.collation(c, name)
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	}
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}
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func compareCallback(ctx context.Context, mod api.Module, pApp ptr_t, nKey1 int32, pKey1 ptr_t, nKey2 int32, pKey2 ptr_t) uint32 {
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	fn := util.GetHandle(ctx, pApp).(func(a, b []byte) int)
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	return uint32(fn(util.View(mod, pKey1, int64(nKey1)), util.View(mod, pKey2, int64(nKey2))))
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}
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func funcCallback(ctx context.Context, mod api.Module, pCtx, pApp ptr_t, nArg int32, pArg ptr_t) {
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	args := getFuncArgs()
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	defer putFuncArgs(args)
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	db := ctx.Value(connKey{}).(*Conn)
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	fn := util.GetHandle(db.ctx, pApp).(ScalarFunction)
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	callbackArgs(db, args[:nArg], pArg)
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	fn(Context{db, pCtx}, args[:nArg]...)
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}
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func stepCallback(ctx context.Context, mod api.Module, pCtx, pAgg, pApp ptr_t, nArg int32, pArg ptr_t) {
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	args := getFuncArgs()
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	defer putFuncArgs(args)
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	db := ctx.Value(connKey{}).(*Conn)
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	callbackArgs(db, args[:nArg], pArg)
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	fn, _ := callbackAggregate(db, pAgg, pApp)
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	fn.Step(Context{db, pCtx}, args[:nArg]...)
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}
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func finalCallback(ctx context.Context, mod api.Module, pCtx, pAgg, pApp ptr_t) {
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	db := ctx.Value(connKey{}).(*Conn)
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	fn, handle := callbackAggregate(db, pAgg, pApp)
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	fn.Value(Context{db, pCtx})
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	if err := util.DelHandle(ctx, handle); err != nil {
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		Context{db, pCtx}.ResultError(err)
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		return // notest
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	}
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}
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func valueCallback(ctx context.Context, mod api.Module, pCtx, pAgg ptr_t) {
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	db := ctx.Value(connKey{}).(*Conn)
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	fn := util.GetHandle(db.ctx, pAgg).(AggregateFunction)
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	fn.Value(Context{db, pCtx})
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}
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func inverseCallback(ctx context.Context, mod api.Module, pCtx, pAgg ptr_t, nArg int32, pArg ptr_t) {
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	args := getFuncArgs()
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	defer putFuncArgs(args)
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	db := ctx.Value(connKey{}).(*Conn)
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	callbackArgs(db, args[:nArg], pArg)
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	fn := util.GetHandle(db.ctx, pAgg).(WindowFunction)
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	fn.Inverse(Context{db, pCtx}, args[:nArg]...)
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}
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func callbackAggregate(db *Conn, pAgg, pApp ptr_t) (AggregateFunction, ptr_t) {
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	if pApp == 0 {
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		handle := util.Read32[ptr_t](db.mod, pAgg)
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		return util.GetHandle(db.ctx, handle).(AggregateFunction), handle
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	}
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	// We need to create the aggregate.
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	fn := util.GetHandle(db.ctx, pApp).(func() AggregateFunction)()
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	if pAgg != 0 {
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		handle := util.AddHandle(db.ctx, fn)
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		util.Write32(db.mod, pAgg, handle)
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		return fn, handle
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	}
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	return fn, 0
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}
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func callbackArgs(db *Conn, arg []Value, pArg ptr_t) {
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	for i := range arg {
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		arg[i] = Value{
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			c:      db,
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			handle: util.Read32[ptr_t](db.mod, pArg+ptr_t(i)*ptrlen),
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		}
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	}
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}
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var funcArgsPool sync.Pool
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func putFuncArgs(p *[_MAX_FUNCTION_ARG]Value) {
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	funcArgsPool.Put(p)
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}
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func getFuncArgs() *[_MAX_FUNCTION_ARG]Value {
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	if p := funcArgsPool.Get(); p == nil {
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		return new([_MAX_FUNCTION_ARG]Value)
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	} else {
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		return p.(*[_MAX_FUNCTION_ARG]Value)
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	}
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}
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