mirror of
https://github.com/MontFerret/ferret.git
synced 2024-12-14 11:23:02 +02:00
86 lines
1.6 KiB
Go
86 lines
1.6 KiB
Go
package main
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import (
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"context"
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"encoding/json"
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"fmt"
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"os"
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"strings"
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"github.com/MontFerret/ferret/pkg/compiler"
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"github.com/MontFerret/ferret/pkg/runtime/core"
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"github.com/MontFerret/ferret/pkg/runtime/values"
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)
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func main() {
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strs, err := getStrings()
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if err != nil {
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fmt.Println(err)
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os.Exit(1)
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}
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for _, str := range strs {
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fmt.Println(str)
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}
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}
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func getStrings() ([]string, error) {
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// function implements is a type of a function that ferret supports as a runtime function
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transform := func(ctx context.Context, args ...core.Value) (core.Value, error) {
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// it's just a helper function which helps to validate a number of passed args
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err := core.ValidateArgs(args, 1, 1)
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if err != nil {
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// it's recommended to return built-in None type, instead of nil
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return values.None, err
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}
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// this is another helper functions allowing to do type validation
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err = core.ValidateType(args[0], core.StringType)
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if err != nil {
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return values.None, err
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}
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// cast to built-in string type
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str := args[0].(values.String)
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return values.NewString(strings.ToUpper(str.String() + "_ferret")), nil
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}
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query := `
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FOR el IN ["foo", "bar", "qaz"]
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// conventionally all functions are registered in upper case
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RETURN TRANSFORM(el)
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`
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comp := compiler.New()
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if err := comp.RegisterFunction("transform", transform); err != nil {
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return nil, err
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}
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program, err := comp.Compile(query)
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if err != nil {
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return nil, err
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}
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out, err := program.Run(context.Background())
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if err != nil {
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return nil, err
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}
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res := make([]string, 0, 3)
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err = json.Unmarshal(out, &res)
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if err != nil {
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return nil, err
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}
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return res, nil
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}
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