Initial commit

8 files changed, 428 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
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index 0000000..e660fd9
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+bin/
diff --git a/LICENSE b/LICENSE
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index 0000000..65afc42
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,19 @@
+Copyright © 2023 Gabriel A. Giovanini
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the “Software”), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..e6c3c4c
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,14 @@
+test:
+	go test -tags=unit .
+
+doc:
+	godoc \
+		-goroot=${PWD} \
+		-templates="./docs" \
+		-url="/pkg/git.sr.ht/~gabrielgio/pipe/" \
+		> index.html
+
+examples: countlines
+
+countlines:
+	go build -o bin/coutlines ./examples/countlines.go
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..d706bfa
--- /dev/null
+++ b/README.md
@@ -0,0 +1,6 @@
+# PIPE
+
+A simple collection of channel based function make simple function to be
+processed in multiples goroutine and piped.
+
+Check `examples` folder for how to use it.
diff --git a/examples/countlines.go b/examples/countlines.go
new file mode 100644
index 0000000..000efa5
--- /dev/null
+++ b/examples/countlines.go
@@ -0,0 +1,135 @@
+package main
+
+import (
+	"bufio"
+	"errors"
+	"flag"
+	"fmt"
+	"os"
+	"path/filepath"
+	"unicode/utf8"
+
+	"git.sr.ht/~gabrielgio/pipe"
+)
+
+var (
+	InvalidInput = errors.New("It was given a file instead of a folder.")
+	ColorGreen   = "\033[32m"
+	ColorRed     = "\033[31m"
+	ColorReset   = "\033[0m"
+)
+
+type (
+	NonTextError struct {
+		Filename string
+	}
+)
+
+func NewNonTextError(filename string) *NonTextError {
+	return &NonTextError{Filename: filename}
+}
+
+func (b *NonTextError) Error() string {
+	return fmt.Sprintf("Non text file %s", b.Filename)
+}
+
+func main() {
+	err := run()
+	if err != nil {
+		fmt.Printf("Error on main process: %s", err.Error())
+	}
+}
+
+func run() error {
+	var (
+		dir   = flag.String("dir", "", "Folder to recursively search for files. Default: \"\"")
+		quiet = flag.Bool("quiet", false, "If true only outputs the result. Default: false")
+		nproc = flag.Int("nproc", 4, "Number of goroutines used to count. Default: 4")
+	)
+
+	flag.Parse()
+
+	info, err := os.Stat(*dir)
+	if err != nil {
+		return err
+	}
+
+	if !info.IsDir() {
+		return InvalidInput
+	}
+
+	cerr := make(chan error)
+	go func(c <-chan error) {
+		for e := range c {
+			if !*quiet {
+				fmt.Printf("%sERROR%s: %s\n", ColorRed, ColorReset, e.Error())
+			}
+		}
+	}(cerr)
+
+	c := count(*dir, *nproc, cerr)
+	fmt.Printf("%sCOUNT%s: %d\n", ColorGreen, ColorReset, c)
+
+	return nil
+}
+
+func count(dir string, nproc int, cerr chan<- error) int {
+	cfiles := walkFolder(dir)
+	ccount := pipe.ProcWithError(cfiles, cerr, nproc, countLines)
+	return pipe.TailReduceWithError(ccount, cerr, sum, 0)
+}
+
+func sum(acc, lines int) (int, error) {
+	return acc + lines, nil
+}
+
+func countLines(filename string) (int, error) {
+
+	file, err := os.Open(filename)
+	if err != nil {
+		return 0, err
+	}
+
+	defer file.Close()
+
+	fileScanner := bufio.NewScanner(file)
+	fileScanner.Split(bufio.ScanLines)
+
+	var count int
+	for fileScanner.Scan() {
+		if !utf8.ValidString(string(fileScanner.Text())) {
+			return 0, NewNonTextError(filename)
+		}
+		count++
+	}
+
+	return count, nil
+}
+
+func walkFolder(folder string) <-chan string {
+	c := make(chan string)
+
+	go func(folder string, c chan string) {
+		filepath.Walk(folder, func(path string, info os.FileInfo, err error) error {
+			file, err := os.Open(path)
+			if err != nil {
+				return filepath.SkipDir
+			}
+			defer file.Close()
+
+			fileInfo, err := file.Stat()
+			if err != nil {
+				return filepath.SkipDir
+			}
+
+			if !fileInfo.IsDir() {
+				c <- path
+			}
+			return nil
+		})
+		close(c)
+
+	}(folder, c)
+
+	return c
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..bad46aa
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module git.sr.ht/~gabrielgio/pipe
+
+go 1.21.4
diff --git a/pipe.go b/pipe.go
new file mode 100644
index 0000000..08eaa23
--- /dev/null
+++ b/pipe.go
@@ -0,0 +1,128 @@
+package pipe
+
+import (
+	"sync"
+)
+
+var SinkChanError chan error
+
+func init() {
+	SinkChanError = make(chan error)
+	go func() {
+		for range SinkChanError {
+		}
+	}()
+}
+
+// Proc maps cin into a channel by applying proc and outputs to its return.
+func Proc[T any, V any](cin <-chan T, count int, proc func(T) (V, error)) <-chan V {
+	return ProcWithError(cin, SinkChanError, count, proc)
+}
+
+// ProcWithError maps cin into a channel by applying proc and outputs to its return.
+func ProcWithError[T any, V any](cin <-chan T, cerr chan<- error, count int, proc func(T) (V, error)) <-chan V {
+	cout := make(chan V)
+	var wg sync.WaitGroup
+
+	for i := 0; i < count; i++ {
+		wg.Add(1)
+		go func(<-chan T, chan<- V) {
+			for i := range cin {
+				v, err := proc(i)
+				if err == nil {
+					cout <- v
+				} else {
+					cerr <- err
+				}
+			}
+			wg.Done()
+		}(cin, cout)
+	}
+
+	go func() {
+		wg.Wait()
+		close(cout)
+	}()
+
+	return cout
+}
+
+func noop[T any](_ T) {}
+
+// Wait waits a channel to close, it ends a chain of procs.
+func Wait[T any](cin <-chan T) {
+	for v := range cin {
+		noop(v)
+	}
+}
+
+// TailProc waits a channel to close by applying proc to it.
+// It does not return a channel since its meant to end a chain of goroutine+channel.
+func TailProc[T any](cin <-chan T, count int, proc func(T) error) {
+	TailProcWithError(cin, SinkChanError, count, proc)
+}
+
+// TailProcWithError waits a channel to close by applying proc to it.
+// It does not return a channel since its meant to end a chain of goroutine+channel.
+func TailProcWithError[T any](cin <-chan T, cerr chan<- error, count int, proc func(T) error) {
+	var wg sync.WaitGroup
+
+	for i := 0; i < count; i++ {
+		wg.Add(1)
+		go func(<-chan T) {
+			for i := range cin {
+				if err := proc(i); err != nil {
+					cerr <- err
+				}
+			}
+			wg.Done()
+
+		}(cin)
+	}
+	wg.Wait()
+}
+
+func TailReduce[T any, V any](cin <-chan T, red func(V, T) (V, error), vinit V) V {
+	return TailReduceWithError(cin, SinkChanError, red, vinit)
+}
+
+func TailReduceWithError[T any, V any](cin <-chan T, cerr chan<- error, red func(V, T) (V, error), vinit V) V {
+	acc := vinit
+
+	for i := range cin {
+		if a, err := red(acc, i); err != nil {
+			cerr <- err
+		} else {
+			acc = a
+		}
+	}
+
+	return acc
+}
+
+// Yield returna a channel from a slice.
+// It will pipe in into a chan returned by the function.
+func Yield[T any](in []T) <-chan T {
+	cout := make(chan T)
+
+	go func(chan<- T) {
+		for _, a := range in {
+			cout <- a
+		}
+		close(cout)
+	}(cout)
+
+	return cout
+}
+
+// Map is a classic map.
+// It gets vs apply m to it and return its value n times.
+func Map[T any, V any](m func(T) V, vs []T) []V {
+	result := make([]V, len(vs))
+
+	for i, v := range vs {
+		result[i] = m(v)
+	}
+
+	return result
+}
diff --git a/pipe_test.go b/pipe_test.go
new file mode 100644
index 0000000..804adcc
--- /dev/null
+++ b/pipe_test.go
@@ -0,0 +1,122 @@
+//go:build unit
+
+package pipe
+
+import (
+	"testing"
+)
+
+const (
+	Values     = 999
+	Multiplier = 1000
+)
+
+type buffer struct {
+	value int
+}
+
+func TestProc(t *testing.T) {
+	c := createCountPipe()
+	am := Proc(c, 8, multiply)
+	ad := Proc(am, 8, devide)
+	a := Proc(ad, 8, multiply)
+
+	out := make([]int, Values-1)
+
+	count := 0
+	for i := range a {
+		out[count] = i
+		count++
+	}
+
+	for _, v := range out {
+		if v < Multiplier {
+			t.Errorf("Invalid output %d", v)
+		}
+	}
+}
+
+func TestYield(t *testing.T) {
+	lin := make([]int, Values)
+
+	for i := 0; i < Values; i++ {
+		lin[i] = i
+	}
+
+	cout := Yield(lin)
+
+	count := 0
+	for out := range cout {
+		if out != lin[count] {
+			t.Errorf("Invalid output %d", out)
+		}
+		count++
+	}
+}
+
+func TestTailProc(t *testing.T) {
+	buffers := createBuffers()
+	c := Yield(buffers)
+	am := Proc(c, 8, multiplyBuffer)
+	TailProc(am, 8, devideBuffer)
+
+	for i, v := range buffers {
+		if v.value != i {
+			t.Errorf("Invalid output %d != %d", v.value, i)
+		}
+	}
+}
+
+func TestWait(t *testing.T) {
+	buffers := createBuffers()
+	c := Yield(buffers)
+	am := Proc(c, 8, multiplyBuffer)
+	Wait(am)
+
+	for i, v := range buffers {
+		if v.value != (i * Multiplier) {
+			t.Errorf("Invalid output %d != %d", v.value, i)
+		}
+	}
+}
+
+func devideBuffer(in *buffer) error {
+	in.value = in.value / Multiplier
+	return nil
+}
+
+func createBuffers() []*buffer {
+	buffers := make([]*buffer, Values)
+
+	for i := 0; i < Values; i++ {
+		buffers[i] = &buffer{value: i}
+	}
+
+	return buffers
+}
+
+func multiplyBuffer(in *buffer) (*buffer, error) {
+	in.value = in.value * Multiplier
+	return in, nil
+}
+
+func createCountPipe() <-chan int {
+	cout := make(chan int)
+
+	go func(<-chan int) {
+		for i := 1; i < Values; i++ {
+			cout <- i
+		}
+		close(cout)
+	}(cout)
+
+	return cout
+}
+
+func multiply(in int) (int, error) {
+	return in * Multiplier, nil
+}
+
+func devide(in int) (int, error) {
+	return in / Multiplier, nil
+}