lang.ArrayTemplate() (template API)

Unmarshals a data type into a Go struct and returns the results as an array

Description

This is a template API you can use for your custom data types to wrap around an existing Go marshaller and return a Murex array which is consistent with other structures such as nested JSON or YAML documents.

It should only be called from ReadArray() functions.

Because lang.ArrayTemplate() relies on a marshaller, it means any types that rely on this API are not going to be stream-able.

Examples

Example calling lang.ArrayTemplate() function:

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)
}

Detail

API Source:

package lang

import (
	"context"
	"fmt"

	"github.com/lmorg/murex/lang/stdio"
	"github.com/lmorg/murex/utils"
)

// ArrayTemplate is a template function for reading arrays from marshalled data
func ArrayTemplate(ctx context.Context, marshal func(interface{}) ([]byte, error), unmarshal func([]byte, interface{}) error, read stdio.Io, callback func([]byte)) error {
	b, err := read.ReadAll()
	if err != nil {
		return err
	}

	if len(utils.CrLfTrim(b)) == 0 {
		return nil
	}

	var v interface{}
	err = unmarshal(b, &v)

	if err != nil {
		return err
	}

	switch v := v.(type) {
	case string:
		return readArrayByString(v, callback)

	case []string:
		return readArrayBySliceString(ctx, v, callback)

	case []interface{}:
		return readArrayBySliceInterface(ctx, marshal, v, callback)

	case map[string]string:
		return readArrayByMapStrStr(ctx, v, callback)

	case map[string]interface{}:
		return readArrayByMapStrIface(ctx, marshal, v, callback)

	case map[interface{}]string:
		return readArrayByMapIfaceStr(ctx, v, callback)

	case map[interface{}]interface{}:
		return readArrayByMapIfaceIface(ctx, marshal, v, callback)

	default:
		jBytes, err := marshal(v)
		if err != nil {

			return err
		}

		callback(jBytes)

		return nil
	}
}

func readArrayByString(v string, callback func([]byte)) error {
	callback([]byte(v))

	return nil
}

func readArrayBySliceString(ctx context.Context, v []string, callback func([]byte)) error {
	for i := range v {
		select {
		case <-ctx.Done():
			return nil

		default:
			callback([]byte(v[i]))
		}
	}

	return nil
}

func readArrayBySliceInterface(ctx context.Context, marshal func(interface{}) ([]byte, error), v []interface{}, callback func([]byte)) error {
	if len(v) == 0 {
		return nil
	}

	for i := range v {
		select {
		case <-ctx.Done():
			return nil

		default:
			switch v := v[i].(type) {
			case string:
				callback([]byte(v))

			case []byte:
				callback(v)

			default:
				jBytes, err := marshal(v)
				if err != nil {
					return err
				}
				callback(jBytes)
			}
		}
	}

	return nil
}

func readArrayByMapIfaceIface(ctx context.Context, marshal func(interface{}) ([]byte, error), v map[interface{}]interface{}, callback func([]byte)) error {
	for key, val := range v {
		select {
		case <-ctx.Done():
			return nil

		default:
			bKey := []byte(fmt.Sprint(key) + ": ")
			b, err := marshal(val)
			if err != nil {
				return err
			}
			callback(append(bKey, b...))
		}
	}

	return nil
}

func readArrayByMapStrStr(ctx context.Context, v map[string]string, callback func([]byte)) error {
	for key, val := range v {
		select {
		case <-ctx.Done():
			return nil

		default:
			callback([]byte(key + ": " + val))
		}
	}

	return nil
}

func readArrayByMapStrIface(ctx context.Context, marshal func(interface{}) ([]byte, error), v map[string]interface{}, callback func([]byte)) error {
	for key, val := range v {
		select {
		case <-ctx.Done():
			return nil

		default:
			bKey := []byte(key + ": ")
			b, err := marshal(val)
			if err != nil {
				return err
			}
			callback(append(bKey, b...))
		}
	}

	return nil
}

func readArrayByMapIfaceStr(ctx context.Context, v map[interface{}]string, callback func([]byte)) error {
	for key, val := range v {
		select {
		case <-ctx.Done():
			return nil

		default:
			callback([]byte(fmt.Sprint(key) + ": " + val))
		}
	}

	return nil
}

Parameters

1. func(interface{}) ([]byte, error): data type's marshaller
2. func([]byte, interface{}) error: data type's unmarshaller
3. stdio.Io: stream to read from (eg STDIN)
4. func([]byte): callback function to write each array element

See Also

• apis/ReadArray() (type): Read from a data type one array element at a time
• apis/ReadArrayWithType() (type): Read from a data type one array element at a time and return the elements contents and data type
• 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.IndexTemplateObject() (template API): Returns element(s) from a data structure
• apis/lang.IndexTemplateTable() (template API): Returns element(s) from a table

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This document was generated from lang/stdio/interface_doc.yaml.