fix: obey main context

.gitignore

@@ -1,3 +1,2 @@
 cmd
 coverage.out
-example

LICENSE

@@ -1,22 +0,0 @@
-Copyright 2025 Dmitry Fedotov
-
-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.

README.md

@@ -1,137 +0,0 @@
-# package script
-
-This package is intended as a collection of helper functions and tools fow quick construction of scripts that process .csv tables.
-
-Note that this is a work in progress. API is not guaranteed to be stable.
-
-## Example usage
-
-This demonstrates a very basic case: reading from stdin, checking whether array len is 2 and switching array elements.
-
-```go
-package main
-
-import (
-	"context"
-	"errors"
-	"fmt"
-	"os/signal"
-	"syscall"
-
-	"code.uint32.ru/dmitry/script"
-)
-
-func main() {
-	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGTERM, syscall.SIGINT)
-	defer stop()
-
-	reader := script.NewStdinReader()
-	writer := script.NewStdoutWriter()
-
-	processor := func(_ context.Context, in []string) ([]string, error) {
-		if len(in) != 2 {
-			return nil, errors.New("incorrect input len")
-		}
-
-		return []string{in[1], in[0]}, nil
-	}
-
-	conf := script.RunConfig{
-		Input:     reader,
-		Output:    writer,
-		Processor: processor,
-	}
-
-	if err := script.Run(ctx, conf); err != nil {
-		fmt.Println(err)
-	}
-}
-```
-
-A more conplicated example featuring a processor which is itself a struct with external dependency.
-
-```go
-package main
-
-import (
-	"context"
-	"fmt"
-	"os/signal"
-	"syscall"
-
-	"code.uint32.ru/dmitry/script"
-)
-
-// ExternalDep represent an external dependency
-// which your script utilizes. This can be a DB connection etc.
-type ExternalDep interface {
-	QueryID(string) ([]string, error)
-}
-
-type Processor struct {
-	dep ExternalDep
-}
-
-func New(e ExternalDep) *Processor {
-
-	return &Processor{
-		dep: e,
-	}
-}
-
-func (p *Processor) Process(ctx context.Context, in []string) ([]string, error) {
-	var out []string
-
-	result, err := p.dep.QueryID(in[0])
-	if err != nil {
-		// you can as well record the error and continue
-		// processing without yielding the error here
-		return nil, err
-	}
-
-	out = append(out, result...)
-	out = append(out, "processed")
-
-	return out, nil
-}
-
-func main() {
-	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGTERM, syscall.SIGINT)
-	defer stop()
-
-	r, err := script.NewCSVReader("/tmp/some_file.csv")
-	if err != nil {
-		panic(err)
-	}
-
-	defer func() {
-		if err := r.Close(); err != nil {
-			fmt.Println("err closing reader", err)
-		}
-	}()
-
-	w, err := script.NewCSVWriter("/tmp/some_output.csv")
-	if err != nil {
-		panic(err)
-	}
-
-	defer func() {
-		if err := w.Close(); err != nil {
-			fmt.Println("err closing writer", err)
-		}
-	}()
-
-    // intializing the processor
-	p := New(ExternalDep(nil))
-
-	conf := script.RunConfig{
-		Input:     r,
-		Output:    w,
-		Processor: p.Process, // Process implements script.Processor
-	}
-
-	if err := script.Run(ctx, conf); err != nil {
-		fmt.Println(err)
-	}
-}
-```

input_mem.go

@@ -1,6 +1,7 @@
 package script
 
 import (
+	"context"
 	"io"
 )
 
@@ -15,7 +16,7 @@ func NewMemReader(records [][]string) *MemReader {
 	}
 }
 
-func (m *MemReader) Read() ([]string, error) {
+func (m *MemReader) Read(context.Context) ([]string, error) {
 	if m.curr == len(m.rows) || len(m.rows) == 0 {
 		return nil, io.EOF
 	}

input_scv.go

@@ -1,6 +1,7 @@
 package script
 
 import (
+	"context"
 	"encoding/csv"
 	"os"
 )
@@ -15,7 +16,7 @@ type CSVReader struct {
 	rdr *csv.Reader
 }
 
-func (c *CSVReader) Read() ([]string, error) {
+func (c *CSVReader) Read(context.Context) ([]string, error) {
 	return c.rdr.Read()
 }
 

input_stdin.go

@@ -2,6 +2,7 @@ package script
 
 import (
 	"bufio"
+	"context"
 	"io"
 	"os"
 	"strings"
@@ -22,7 +23,7 @@ func NewStdinReader() *StdinReader {
 // then splits result at "," separator and returns
 // the resulting slice.
 // It returns EOF when nothing left to read.
-func (s *StdinReader) Read() ([]string, error) {
+func (s *StdinReader) Read(_ context.Context) ([]string, error) {
 	if !s.scanner.Scan() {
 		err := s.scanner.Err()
 		if err == nil {

output_csv.go

@@ -1,6 +1,7 @@
 package script
 
 import (
+	"context"
 	"encoding/csv"
 	"errors"
 	"os"
@@ -19,7 +20,7 @@ type CSVWriter struct {
 }
 
 // Write writer row to csv. Writes are buffered
-func (c *CSVWriter) Write(record []string) error {
+func (c *CSVWriter) Write(_ context.Context, record []string) error {
 	err := c.wr.Write(record)
 	c.err = err
 

output_discard.go

@@ -1,11 +1,13 @@
 package script
 
+import "context"
+
 type NopWriter struct{}
 
 func NewNopWriter() *NopWriter {
 	return new(NopWriter)
 }
 
-func (d *NopWriter) Write([]string) error {
+func (d *NopWriter) Write(context.Context, []string) error {
 	return nil
 }

output_mem.go

@@ -1,5 +1,7 @@
 package script
 
+import "context"
+
 type MemWriter struct {
 	rows [][]string
 }
@@ -8,7 +10,7 @@ func NewMemWriter() *MemWriter {
 	return new(MemWriter)
 }
 
-func (m *MemWriter) Write(record []string) error {
+func (m *MemWriter) Write(_ context.Context, record []string) error {
 	m.rows = append(m.rows, record)
 
 	return nil

output_stdout.go

@@ -1,6 +1,7 @@
 package script
 
 import (
+	"context"
 	"os"
 	"strings"
 )
@@ -11,7 +12,7 @@ func NewStdoutWriter() *StdoutWriter {
 	return new(StdoutWriter)
 }
 
-func (s *StdoutWriter) Write(in []string) error {
+func (s *StdoutWriter) Write(_ context.Context, in []string) error {
 	_, err := os.Stdout.WriteString(strings.Join(in, ",") + "\n")
 	return err
 }

runner.go

@@ -28,13 +28,13 @@ type Reader interface {
 	// Read is called by Processor to obtain input
 	// for processing. Read must return EOF/io.EOF to indicate
 	// that there is no more input.
-	Read() ([]string, error)
+	Read(context.Context) ([]string, error)
 }
 
 type Writer interface {
 	// Write is called by Processor to record
 	// output.
-	Write([]string) error
+	Write(context.Context, []string) error
 }
 
 // Processor accepts string slice, does what it should
@@ -76,7 +76,7 @@ func Run(ctx context.Context, r RunConfig) error {
 		defer close(rdch)
 
 		for range r.Offset {
-			_, err := r.Input.Read()
+			_, err := r.Input.Read(ctx)
 			if err != nil {
 				return fmt.Errorf("could not advance to required offset: %w", err)
 			}
@@ -84,7 +84,7 @@ func Run(ctx context.Context, r RunConfig) error {
 
 		count := 0
 		for {
-			inp, err := r.Input.Read()
+			inp, err := r.Input.Read(ctx)
 			if err != nil && errors.Is(err, EOF) {
 				return nil
 			} else if err != nil {
@@ -111,10 +111,8 @@ func Run(ctx context.Context, r RunConfig) error {
 	grp.Go(func() error {
 		// not paying attention to context here
 		// because we must complete writes
-		// this is run within group so that write
-		// error would cancel group context
 		for outp := range wrch {
-			if err := r.Output.Write(outp); err != nil {
+			if err := r.Output.Write(ctx, outp); err != nil {
 				return err
 			}
 		}

runner_test.go

@@ -41,7 +41,7 @@ func TestBasicRun(t *testing.T) {
 
 type infiniteReader struct{}
 
-func (ir *infiniteReader) Read() ([]string, error) {
+func (ir *infiniteReader) Read(_ context.Context) ([]string, error) {
 	return []string{"infinity", "looks", "like", "this"}, nil
 }