Read from a data type one array element at a time
This is a function you would write when programming a Murex data-type.
It's called by builtins to allow them to read data structures one array element at a time.
The purpose of this function is to allow builtins to support sequential reads (where possible) and also create a standard interface for builtins, thus allowing them to be data-type agnostic.
Registering your ReadArray()
// To avoid confusion, this should only happen inside func init()
stdio.RegisterReadArray(/* your type name */, /* your readArray func */)Example ReadArray() function:
package string
import (
"bufio"
"bytes"
"context"
"fmt"
"github.com/lmorg/murex/lang/stdio"
"github.com/lmorg/murex/lang/types"
)
func readArray(ctx context.Context, read stdio.Io, callback func([]byte)) error {
scanner := bufio.NewScanner(read)
for scanner.Scan() {
select {
case <-ctx.Done():
return scanner.Err()
default:
callback(bytes.TrimSpace(scanner.Bytes()))
}
}
err := scanner.Err()
if err != nil {
return fmt.Errorf("error while reading a %s array: %s", types.String, err.Error())
}
return nil
}If your data type is not a stream-able array, it is then recommended that
you pass your array to lang.ArrayTemplate() which is a handler to convert Go
structures into Murex arrays. This also makes writing ReadArray() handlers
easier since you can just pass lang.ArrayTemplate() your marshaller.
For example:
package json
import (
"context"
"github.com/lmorg/murex/lang"
"github.com/lmorg/murex/lang/stdio"
"github.com/lmorg/murex/utils/json"
)
func readArray(ctx context.Context, read stdio.Io, callback func([]byte)) error {
// Create a marshaller function to pass to ArrayTemplate
marshaller := func(v interface{}) ([]byte, error) {
return json.Marshal(v, read.IsTTY())
}
return lang.ArrayTemplate(ctx, marshaller, json.Unmarshal, read, callback)
}The downside of this is that you're then unmarshalling the entire file, which could be slow on large files and also breaks the streaming nature of UNIX pipelines.
stdio.Io: stream to read from (eg stdin)func([]byte): callback function. Each callback will be a []byte slice containing an array element
- apis/
ReadIndex()(type): Data type handler for the index,[, builtin - apis/
ReadMap()(type): Treat data type as a key/value structure and read its contents - apis/
ReadNotIndex()(type): Data type handler for the bang-prefixed index,![, builtin - apis/
WriteArray()(type): Write a data type, one array element at a time - apis/
lang.ArrayTemplate()(template API): Unmarshals a data type into a Go struct and returns the results as an array - apis/
lang.ArrayWithTypeTemplate()(template API): Unmarshals a data type into a Go struct and returns the results as an array with data type included
This document was generated from lang/stdio/interface_doc.yaml.