README
¶
GoStream
GoStream是一个参考Java Stream API，基于go-linq实现的流式数据处理库。 它可以声明式地对数据进行转换、过滤、排序、分组、收集，而无需关心操作细节。
Get GoStream
go get github.com/a2dict/gostream
Example
See walkthrough.go
Base Example
package main
import (
"fmt"
"reflect"
. "github.com/a2dict/gostream/core"
)
func main() {
input := []int{4, 3, 2, 1}
want := []int{6, 8}
got := From(input).Map(func(it interface{}) interface{} {
return 2 * it.(int)
}).Filter(func(it interface{}) bool {
return it.(int) > 5
}).SortedBy(func(it interface{}) interface{} {
return it
}).Collect(ToSlice([]int(nil)))
if !reflect.DeepEqual(got, want) {
panic(fmt.Sprintf("%v != %v", got, want))
}
// walkthrough()
}
Map & FlatMap
Map和FlatMap的差别在于：FlatMap的mapper返回一个Stream，用于将多级数据打扁。
input := [][]int{{3, 2, 1}, {6, 5, 4}, {9, 8, 7}}
want := []int{1, 2, 3, 4, 5, 6, 7, 8, 9}
got := From(input).FlatMap(func(it interface{}) Stream {
return From(it)
}).SortedBy(func(it interface{}) interface{} {
return it
}).Collect(ToSlice([]int{}))
Collect ToSlice & ToMap
Collect将数据收集起来。受限于go的类型系统，需要显示传类型参数——一个目标类型的实例，可以为nil。
intput := []int{1, 2, 3, 4, 5}
identity := func(it interface{}) interface{} { return it }
// []int{1, 2, 3, 4, 5}
gotSlice := From(intput).Collect(ToSlice([]int{}))
// map[int]int{1: 1, 2: 2, 3: 3, 4: 4, 5: 5}
gotMap := From(intput).Collect(ToMap(map[int]int(nil), identity, identity))
Collect GroupBy
GroupBy定义一个分组收集器，参数依序分别为 类型参数、分类方法、下游收集器。 GroupBy可以和ToSlice、ToMap组合，GroupBy也可以多级嵌套，实现多级分组。
GroupBy(typ interface{}, classifier normalFn, downstream collector) collector
假设一组货物，需要按Status,Location进行分组，目标类型为 map[int]map[string][]*Cargo。
// Cargo 货物实体
type Cargo struct {
ID int
Name string
Location string
Status int
}
input := []*Cargo{{
ID: 1,
Name: "foo",
Location: "shenzhen",
Status: 1,
}, {
ID: 2,
Name: "bar",
Location: "shenzhen",
Status: 0,
}, {
ID: 3,
Name: "zhang",
Location: "guangzhou",
Status: 1,
}}
getStatus := func(it interface{}) interface{} { return it.(*Cargo).Status }
getLocation := func(it interface{}) interface{} { return it.(*Cargo).Location }
// result type: map[int]map[string][]*Cargo
got := From(input).Collect(
GroupBy(map[int]map[string][]*Cargo(nil), getStatus,
GroupBy(map[string][]*Cargo(nil), getLocation,
ToSlice([]*Cargo(nil)))))
Flatten Group
这个示例演示如何将多级分组Map扁平化。map[int]map[string][]*Cargo => []*Cargo
From(cargoByLocationByTo).FlatMap(func(it interface{}) Stream {
return From(it.(KeyValue).Value).FlatMap(func(it2 interface{}) Stream {
return From(it2.(KeyValue).Value)
})
}).Collect(ToSlice([]*Cargo{}))
Benchmark
$ go test -bench=.
goos: darwin
goarch: amd64
pkg: github.com/a2dict/gostream
BenchmarkToSliceRaw-12 8216 132435 ns/op
BenchmarkToSliceStreamForeach-12 639 1819347 ns/op
BenchmarkCollectToSlice-12 88 13006774 ns/op
BenchmarkCollectToSliceV2-12 308 3847322 ns/op
BenchmarkLinqToSlice-12 340 3513771 ns/op
BenchmarkToMapRaw-12 184 6195945 ns/op
BenchmarkCollectToMap-12 97 12378528 ns/op
BenchmarkCollectToMapV2-12 98 12409819 ns/op
BenchmarkLinqToMap-12 100 12293144 ns/op
BenchmarkGroupByRaw-12 86 12673383 ns/op
BenchmarkGroupBy-12 22 48737249 ns/op
BenchmarkGroupByV2-12 9 116926833 ns/op
BenchmarkLinqGroupBy-12 19 61038649 ns/op
BenchmarkPartition-12 171 6949116 ns/op
BenchmarkCountRaw-12 810 1468941 ns/op
BenchmarkCount-12 170 7044074 ns/op
BenchmarkCountV2-12 813 1468029 ns/op
BenchmarkGroupCount-12 33 35121443 ns/op
BenchmarkGroupCountV2-12 15 70305638 ns/op
Documentation
¶
Index ¶
- func Count() collector
- func CountV2() collectorV2
- func GroupBy(typ interface{}, classifier normalizedFn, downstream collector) collector
- func GroupByV2(typ interface{}, classifier normalizedFn, downstream collectorV2) collectorV2
- func ToMap(typ interface{}, keyMapper, valueMapper normalizedFn) collector
- func ToMapV2(typ interface{}, keyMapper, valueMapper normalizedFn) collectorV2
- func ToSlice(typ interface{}) collector
- func ToSliceBy(typ interface{}, mapper normalizedFn) collector
- func ToSliceByV2(typ interface{}, mapper normalizedFn) collectorV2
- func ToSliceV2(typ interface{}) collectorV2
- type KeyValue
- type Stream
- func (s Stream) All(predicate func(interface{}) bool) bool
- func (s Stream) Any() bool
- func (s Stream) AnyWith(predicate func(interface{}) bool) bool
- func (s Stream) Collect(c collector) interface{}
- func (s Stream) CollectV2(c collectorV2) interface{}
- func (s Stream) Contains(value interface{}) bool
- func (s Stream) Count() int
- func (s Stream) Drop(n int) Stream
- func (s Stream) Filter(predicate func(interface{}) bool) Stream
- func (s Stream) First() (interface{}, bool)
- func (s Stream) FlatMap(mapper func(interface{}) Stream) Stream
- func (s Stream) ForEach(action func(interface{}))
- func (s Stream) ForEachIndexed(action func(int, interface{}))
- func (s Stream) Last() (interface{}, bool)
- func (s Stream) Limit(n int) Stream
- func (s Stream) Linq() linq.Query
- func (s Stream) Map(mapper normalizedFn) Stream
- func (s Stream) OutMap(out interface{})
- func (s Stream) OutSlice(out interface{})
- func (s Stream) Partition(typ interface{}, size int) Stream
- func (s Stream) Peek(fn func(interface{})) Stream
- func (s Stream) Process(fn func(interface{}) error) error
- func (s Stream) Reduce(accumulator accumulatorFn) interface{}
- func (s Stream) ReduceWith(seed interface{}, accumulator accumulatorFn) interface{}
- func (s Stream) SortedBy(fn normalizedFn) Stream
- func (s Stream) SortedDescBy(fn normalizedFn) Stream
- func (s Stream) ToMap(typ interface{}) interface{}
- func (s Stream) ToSlice(typ interface{}) interface{}
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func GroupBy ¶
func GroupBy(typ interface{}, classifier normalizedFn, downstream collector) collector
GroupBy 分组收集器，将item分组收集。 参数说明：
classifier 分组函数 downstream 下游收集器
func GroupByV2 ¶
func GroupByV2(typ interface{}, classifier normalizedFn, downstream collectorV2) collectorV2
GroupByV2 ...
func ToMapV2 ¶
func ToMapV2(typ interface{}, keyMapper, valueMapper normalizedFn) collectorV2
ToMapV2 ...
func ToSlice ¶
func ToSlice(typ interface{}) collector
ToSlice 收集器，将item收集为slice。 typ为类型参数，允许为nil。 eg: []int{} or []int(nil)
func ToSliceBy ¶
func ToSliceBy(typ interface{}, mapper normalizedFn) collector
ToSliceBy 收集器，将mapper应用于每一个item，再收集结果
func ToSliceByV2 ¶
func ToSliceByV2(typ interface{}, mapper normalizedFn) collectorV2
ToSliceByV2 ...
Types ¶
type Stream ¶
type Stream linq.Query
Stream 流
func (Stream) CollectV2 ¶
func (s Stream) CollectV2(c collectorV2) interface{}
CollectV2 Collect的v2版本，基于go-linq实现
func (Stream) ForEachIndexed ¶
ForEachIndexed 带index遍历item
func (Stream) ReduceWith ¶
func (s Stream) ReduceWith(seed interface{}, accumulator accumulatorFn) interface{}
ReduceWith ...
Source Files
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Directories
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