gopp/tengo.go

package pp

import (
	"github.com/d5/tengo/v2"
	"github.com/d5/tengo/v2/stdlib"
	"fmt"
	"context"
)

type Tengo struct {
	head string
	modules *tengo.ModuleMap
}

func NewTengo() *Tengo {
	evaler := &Tengo{}
	evaler.modules = stdlib.GetModuleMap(stdlib.AllModuleNames()...)
	return evaler
}

func (pp *Tengo) Tags() [2]string {
	return [2]string{
		"<?",
		"?>",
	}
}

// Simple Evaler implementation for the Tengo language
func (pp *Tengo) Eval(filePath string, codes []string) ([]string, error) {
	const retHead = `
		__ret_one__ := ""
		printf := func(format, ...vals) {
			__ret_one__ += sprintf(format, vals...)
		}

		print := func(...vals) {
			__ret_one__ += sprint(vals...)
		}

		println := func(...vals) {
			__ret_one__ += sprintln(vals...)
		}
	`

	const retSeparator = `
		__Separate(__ret_one__)
		__ret_one__ = ""
	`
	rets := []string{}


	fullCode := retHead + "\n" + pp.head
	for _, code := range codes {
		fullCode += "\n" + code + retSeparator + "\n"
	}
	script := tengo.NewScript([]byte(fullCode))
	script.SetImports(pp.modules)
	script.EnableFileImport(true)
	script.SetImportDir(".")
	err := script.Add("sprintf", &tengo.UserFunction{
			Value: func(args ...tengo.Object) (tengo.Object, error){
				if len(args) < 1 {
					return nil, tengo.ErrWrongNumArguments
				}
				format, ok := tengo.ToString(args[0])
				if !ok {
					return nil, tengo.ErrInvalidArgumentType{
						Expected: "string",
					}
				}
				gargs := make([]any, len(args) - 1)
				for i := range gargs {
					gargs[i] = tengo.ToInterface(args[i+1])
					//fmt.Printf("shit: %q\n", gargs[i])
				}
				str := fmt.Sprintf(format, gargs...)
				return tengo.FromInterface(str)
			},
		},
	)
	if err != nil {
		return nil, err
	}
	err = script.Add("sprint", &tengo.UserFunction{
			Value: func(args ...tengo.Object) (tengo.Object, error){
				gargs := make([]any, len(args))
				for i := range gargs {
					gargs[i] = tengo.ToInterface(args[i])
				}
				str := fmt.Sprint(gargs...)
				return tengo.FromInterface(str)
			},
		},
	)
	if err != nil {
		return nil, err
	}
	err = script.Add("sprintln", &tengo.UserFunction{
			Value: func(args ...tengo.Object) (tengo.Object, error){
				gargs := make([]any, len(args))
				for i := range gargs {
					gargs[i] = tengo.ToInterface(args[i])
				}
				str := fmt.Sprintln(gargs...)
				return tengo.FromInterface(str)
			},
		},
	)
	if err != nil {
		return nil, err
	}
	err = script.Add("__Separate", &tengo.UserFunction{
			Value: func(args ...tengo.Object) (tengo.Object, error){
				if len(args) < 1 {
					return nil, tengo.ErrWrongNumArguments
				}
				str, ok := tengo.ToString(args[0])
				if !ok {
					return nil, tengo.ErrInvalidArgumentType{
					}
				}
				rets = append(rets, str)
				return nil, nil
			},
		},
	)
	if err != nil {
		return nil, err
	}

	_, err = script.RunContext(context.Background())
	if err != nil {
		return nil, err
	}

	return rets, nil
}