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			230 lines
		
	
	
	
		
			6.9 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			230 lines
		
	
	
	
		
			6.9 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
| package sqlite3
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| 
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| import (
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| 	"context"
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| 	"sync"
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| 
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| 	"github.com/tetratelabs/wazero/api"
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| 
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| 	"github.com/ncruces/go-sqlite3/internal/util"
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| )
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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 uint64
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| 	if cb != nil {
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| 		enable = 1
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| 	}
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| 	r := c.call("sqlite3_collation_needed_go", uint64(c.handle), enable)
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| 	if err := c.error(r); 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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| 
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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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| 	r := c.call("sqlite3_anycollseq_init", uint64(c.handle), 0, 0)
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| 	if err := c.error(r); 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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| 
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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 uint32
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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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| 	r := c.call("sqlite3_create_collation_go",
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| 		uint64(c.handle), uint64(namePtr), uint64(funcPtr))
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| 	return c.error(r)
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| }
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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 uint32
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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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| 	r := c.call("sqlite3_create_function_go",
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| 		uint64(c.handle), uint64(namePtr), uint64(nArg),
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| 		uint64(flag), uint64(funcPtr))
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| 	return c.error(r)
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| }
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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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| 
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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 uint32
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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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| 	r := c.call(call,
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| 		uint64(c.handle), uint64(namePtr), uint64(nArg),
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| 		uint64(flag), uint64(funcPtr))
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| 	return c.error(r)
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| }
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 	r := c.call("sqlite3_overload_function",
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| 		uint64(c.handle), uint64(namePtr), uint64(nArg))
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| 	return c.error(r)
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| }
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| 
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| func destroyCallback(ctx context.Context, mod api.Module, pApp uint32) {
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| 	util.DelHandle(ctx, pApp)
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| }
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| 
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| func collationCallback(ctx context.Context, mod api.Module, pArg, pDB, eTextRep, zName uint32) {
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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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| 
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| func compareCallback(ctx context.Context, mod api.Module, pApp, nKey1, pKey1, nKey2, pKey2 uint32) 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, uint64(nKey1)), util.View(mod, pKey2, uint64(nKey2))))
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| }
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| 
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| func funcCallback(ctx context.Context, mod api.Module, pCtx, pApp, nArg, pArg uint32) {
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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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| 
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| func stepCallback(ctx context.Context, mod api.Module, pCtx, pAgg, pApp, nArg, pArg uint32) {
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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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| 
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| func finalCallback(ctx context.Context, mod api.Module, pCtx, pAgg, pApp uint32) {
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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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| 	util.DelHandle(ctx, handle)
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| }
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| 
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| func valueCallback(ctx context.Context, mod api.Module, pCtx, pAgg uint32) {
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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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| 
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| func inverseCallback(ctx context.Context, mod api.Module, pCtx, pAgg, nArg, pArg uint32) {
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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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| 
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| func callbackAggregate(db *Conn, pAgg, pApp uint32) (AggregateFunction, uint32) {
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| 	if pApp == 0 {
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| 		handle := util.ReadUint32(db.mod, pAgg)
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| 		return util.GetHandle(db.ctx, handle).(AggregateFunction), handle
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| 	}
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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.WriteUint32(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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| 
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| func callbackArgs(db *Conn, arg []Value, pArg uint32) {
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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.ReadUint32(db.mod, pArg+ptrlen*uint32(i)),
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| 		}
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| 	}
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| }
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| 
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| var funcArgsPool sync.Pool
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| 
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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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| 
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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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