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templates.go
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templates.go
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package gencel
import (
"fmt"
"strings"
)
func getArgs(args []Ident) string {
output := make([]string, 0, len(args))
for i := range args {
var a string
if args[i].IsEllipsis {
a = "list..."
output = append(output, a)
continue
}
switch args[i].GoType {
case "interface{}":
a = fmt.Sprintf("args[%d]", i)
default:
a = fmt.Sprintf("args[%d].Value().(%s)", i, args[i].GoType)
}
output = append(output, a)
}
return strings.Join(output, ", ")
}
var tplFuncs = map[string]any{
"getReturnIdentifiers": func(args []Ident) string {
var output []string
for i := range args {
output = append(output, fmt.Sprintf("a%d", i))
}
return strings.Join(output, ", ")
},
"fnSuffix": func(args []Ident) string {
var output []string
for _, a := range args {
output = append(output, a.GoType)
}
return strings.Join(output, "_")
},
"getArgs": getArgs,
"getReturnTypes": func(args []Ident) string {
switch len(args) {
case 0:
return "nil"
case 1:
return goTypeToIdent(args[0].GoType).Type
default:
return "cel.DynType"
}
},
}
type VariadicArg struct {
Pos int
Type string
}
func getVariadicArg(items []Ident) *VariadicArg {
for i, a := range items {
if a.IsEllipsis {
return &VariadicArg{Pos: i, Type: a.GoType}
}
}
return nil
}
type funcDefTemplateView struct {
// IdentName is the name of the exported cel func
// in this codebase.
IdentName string
// FnName is the name of the cel func inside the
// cel environment.
FnName string
// FnNameWithNamespace is the name of the cel func inside the
// cel environment that's namespaced by the filename.
// Example: A function IsMax() inside the file math.go would have
// FnNameWithNamespace as math.IsMax.
//
// NOTE: There are some exceptions so not all function names are namespaced.
FnNameWithNamespace string
// Args is the list of arguments of the go func
// that this cel func is encapsulating.
Args []Ident
// ReturnTypes is the list of all returns of the go func
// that this cel func is encapsulating.
ReturnTypes []Ident
// RecvType is the parent type of the member func
// that this cel func is encapsulating.
RecvType string
// VariadicArg indicates whether this func has any ellipsis argument.
VariadicArg *VariadicArg
}
const funcBodyTemplate = `
{{define "body"}}
var x {{.RecvType}}
{{if .VariadicArg}}list := transferSlice[{{.VariadicArg.Type}}](args[{{.VariadicArg.Pos}}].(ref.Val)){{end}}
{{if gt (len .ReturnTypes) 1}}
{{getReturnIdentifiers .ReturnTypes}} := x.{{.FnName}}({{getArgs .Args}})
return types.DefaultTypeAdapter.NativeToValue([]any{
{{getReturnIdentifiers .ReturnTypes}},
})
{{else}}
return types.DefaultTypeAdapter.NativeToValue(x.{{.FnName}}({{getArgs .Args}}))
{{end}}
{{end}}
`
const funcDefTemplate = `
var {{.IdentName}} = cel.Function("{{.FnNameWithNamespace}}",
cel.Overload("{{.FnNameWithNamespace}}_{{fnSuffix .Args}}",
{{if .Args}}
[]*cel.Type{
{{ range $elem := .Args }} {{.Type}}, {{end}}
}{{else}}nil{{end}},
{{getReturnTypes .ReturnTypes}},
cel.FunctionBinding(func(args ...ref.Val) ref.Val {
{{ block "body" . }}{{end}}
}),
),
)
`
type exportFuncsTemplateView struct {
FnNames []string
}
const exportAllTemplate = `
func transferSlice[K any](arg ref.Val) []K {
list, ok := arg.Value().([]ref.Val)
if !ok {
log.Printf("Not a list %T\n", arg.Value())
return nil
}
var out = make([]K, len(list))
for i, val := range list {
out[i] = val.Value().(K)
}
return out
}
var CelEnvOption = []cel.EnvOption{
{{range $fnName := .FnNames}}{{$fnName}},
{{end}}
}
`