fx Package Documentation

The fx package provides a powerful and flexible API for stream processing. It allows users to perform various operations on streams, including filtering, mapping, reducing, grouping, and more.

Function Types

FilterFunc

Defines the method to filter a Stream.

  1. type FilterFunc func(item any) bool

ForAllFunc

Defines the method to handle all elements in a Stream.

  1. type ForAllFunc func(pipe <-chan any)

ForEachFunc

Defines the method to handle each element in a Stream.

  1. type ForEachFunc func(item any)

GenerateFunc

Defines the method to send elements into a Stream.

  1. type GenerateFunc func(source chan<- any)

KeyFunc

Defines the method to generate keys for the elements in a Stream.

  1. type KeyFunc func(item any) any

LessFunc

Defines the method to compare the elements in a Stream.

  1. type LessFunc func(a, b any) bool

MapFunc

Defines the method to map each element to another object in a Stream.

  1. type MapFunc func(item any) any

Option

Defines the method to customize a Stream.

  1. type Option func(opts *rxOptions)

ParallelFunc

Defines the method to handle elements parallelly.

  1. type ParallelFunc func(item any)

ReduceFunc

Defines the method to reduce all the elements in a Stream.

  1. type ReduceFunc func(pipe <-chan any) (any, error)

WalkFunc

Defines the method to walk through all the elements in a Stream.

  1. type WalkFunc func(item any, pipe chan<- any)

Stream

A Stream is a stream that can be used to do stream processing.

  1. type Stream struct {
  2.     source <-chan any
  3. }

Functions

Concat

Returns a concatenated Stream.

  1. func Concat(s Stream, others ...Stream) Stream

From

Constructs a Stream from the given GenerateFunc.

  1. func From(generate GenerateFunc) Stream

Just

Converts the given arbitrary items to a Stream.

  1. func Just(items ...any) Stream

Range

Converts the given channel to a Stream.

  1. func Range(source <-chan any) Stream

Stream Methods

AllMatch

Returns whether all elements of this stream match the provided predicate.

  1. func (s Stream) AllMatch(predicate func(item any) bool) bool

AnyMatch

Returns whether any elements of this stream match the provided predicate.

  1. func (s Stream) AnyMatch(predicate func(item any) bool) bool

Buffer

Buffers the items into a queue with size n.

  1. func (s Stream) Buffer(n int) Stream

Concat

Returns a Stream that concatenated other streams.

  1. func (s Stream) Concat(others ...Stream) Stream

Count

Counts the number of elements in the result.

  1. func (s Stream) Count() (count int)

Distinct

Removes the duplicated items based on the given KeyFunc.

  1. func (s Stream) Distinct(fn KeyFunc) Stream

Done

Waits all upstreaming operations to be done.

  1. func (s Stream) Done()

Filter

Filters the items by the given FilterFunc.

  1. func (s Stream) Filter(fn FilterFunc, opts ...Option) Stream

First

Returns the first item, nil if no items.

  1. func (s Stream) First() any

ForAll

Handles the streaming elements from the source and no later streams.

  1. func (s Stream) ForAll(fn ForAllFunc)

ForEach

Seals the Stream with the ForEachFunc on each item, no successive operations.

  1. func (s Stream) ForEach(fn ForEachFunc)

Group

Groups the elements into different groups based on their keys.

  1. func (s Stream) Group(fn KeyFunc) Stream

Head

Returns the first n elements in p.

  1. func (s Stream) Head(n int64) Stream

Last

Returns the last item, or nil if no items.

  1. func (s Stream) Last() (item any)

Map

Converts each item to another corresponding item, which means it’s a 1:1 model.

  1. func (s Stream) Map(fn MapFunc, opts ...Option) Stream

Max

Returns the maximum item from the underlying source.

  1. func (s Stream) Max(less LessFunc) any

Merge

Merges all the items into a slice and generates a new stream.

  1. func (s Stream) Merge() Stream

Min

Returns the minimum item from the underlying source.

  1. func (s Stream) Min(less LessFunc) any

NoneMatch

Returns whether all elements of this stream don’t match the provided predicate.

  1. func (s Stream) NoneMatch(predicate func(item any) bool) bool

Parallel

Applies the given ParallelFunc to each item concurrently with given number of workers.

  1. func (s Stream) Parallel(fn ParallelFunc, opts ...Option)

Reduce

Is a utility method to let the caller deal with the underlying channel.

  1. func (s Stream) Reduce(fn ReduceFunc) (any, error)

Reverse

Reverses the elements in the stream.

  1. func (s Stream) Reverse() Stream

Skip

Returns a Stream that skips n elements.

  1. func (s Stream) Skip(n int64) Stream

Sort

Sorts the items from the underlying source.

  1. func (s Stream) Sort(less LessFunc) Stream

Split

Splits the elements into chunks with size up to n.

  1. func (s Stream) Split(n int) Stream

Tail

Returns the last n elements in p.

  1. func (s Stream) Tail(n int64) Stream

Walk

Lets the callers handle each item. The caller may write zero, one, or more items based on the given item.

  1. func (s Stream) Walk(fn WalkFunc, opts ...Option) Stream

Options

UnlimitedWorkers

Lets the caller use as many workers as the tasks.

  1. func UnlimitedWorkers() Option

WithWorkers

Lets the caller customize the concurrent workers.

  1. func WithWorkers(workers int) Option

Examples

Here are some examples demonstrating how to use the fx package for stream processing operations.

Example 1: Creating a Stream from an Array and Filtering Elements

  1. package main
  3. import (
  4.     "fmt"
  6.     "github.com/zeromicro/go-zero/core/fx"
  7. )
  9. func main() {
  10.     items := []any{1, 2, 3, 4, 5}
  12.     stream := fx.Just(items...).
  13.         Filter(func(item any) bool {
  14.             return item.(int)%2 == 0
  15.         })
  17.     for item := range stream.source {
  18.         fmt.Println(item)
  19.     }
  20. }

Explanation:

  1. Use the Just method to convert an array to a stream.
  2. Use the Filter method to filter out even numbers.
  3. Iterate over the stream and print the results.

Example 2: Processing Stream Elements in Parallel

  1. package main
  3. import (
  4.     "fmt"
  6.     "github.com/zeromicro/go-zero/core/fx"
  7. )
  9. func main() {
  10.     items := []any{1, 2, 3, 4, 5}
  12.     fx.Just(items...).
  13.         Parallel(func(item any) {
  14.             fmt.Printf("Processing %v\n", item)
  15.         }, fx.WithWorkers(3))
  16. }

Explanation:

  1. Use the Just method to convert an array to a stream.
  2. Use the Parallel method to process each element in parallel, specifying 3 workers.
  3. Print each element being processed.

Example 3: Sorting Elements in a Stream

  1. package main
  3. import (
  4.     "fmt"
  6.     "github.com/zeromicro/go-zero/core/fx"
  7. )
  9. func main() {
  10.     items := []any{4, 2, 5, 1, 3}
  12.     stream := fx.Just(items...).
  13.         Sort(func(a, b any) bool {
  14.             return a.(int) < b.(int)
  15.         })
  17.     for item := range stream.source {
  18.         fmt.Println(item)
  19.     }
  20. }

Explanation:

  1. Use the Just method to convert an array to a stream.
  2. Use the Sort method to sort the elements.
  3. Iterate over the stream and print the sorted results.

Example 4: Reducing Elements in a Stream

  1. package main
  3. import (
  4.     "fmt"
  6.     "github.com/zeromicro/go-zero/core/fx"
  7. )
  9. func main() {
  10.     items := []any{1, 2, 3, 4, 5}
  12.     result, _ := fx.Just(items...).
  13.         Reduce(func(pipe <-chan any) (any, error) {
  14.             sum := 0
  15.             for item := range pipe {
  16.                 sum += item.(int)
  17.             }
  18.             return sum, nil
  19.         })
  21.     fmt.Println(result) // Output: 15
  22. }

Explanation:

  1. Use the Just method to convert an array to a stream.
  2. Use the Reduce method to calculate the sum of all elements in the stream.
  3. Print the reduction result.

Example 5: Grouping Elements in a Stream

  1. package main
  3. import (
  4.     "fmt"
  6.     "github.com/zeromicro/go-zero/core/fx"
  7. )
  9. func main() {
  10.     items := []any{"apple", "banana", "avocado", "blueberry"}
  12.     stream := fx.Just(items...).
  13.         Group(func(item any) any {
  14.             return item.(string)[0] // Group by the first letter
  15.         })
  17.     for group := range stream.source {
  18.         fmt.Println(group)
  19.     }
  20. }

Explanation:

  1. Use the Just method to convert an array to a stream.
  2. Use the Group method to group elements by their first letter.
  3. Iterate over the stream and print each group.

These examples demonstrate how the fx package can simplify data processing through stream operations. You can combine and apply these methods according to your specific requirements in your code.