Merge pull request #243 from bytecodealliance/ydnar/stdio

cmd/wit-bindgen-go, internal/witcli, wit: refactor handling of - as stdin

Author: ydnar

CHANGELOG.md

@@ -8,6 +8,11 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 
 - [#240](https://github.com/bytecodealliance/go-modules/issues/240): correctly handle cyclical data structures when generating variant lowering code.
 
+### Changed
+
+- Breaking: package `wit` no longer interprets `-` to read from stdin when loading JSON or WIT using `wit.LoadJSON` or `wit.LoadWIT`. Use `wit.DecodeJSON` or `wit.DecodeWIT` to read JSON or WIT from an `io.Reader`.
+- Breaking: `wit.ParseWIT` has been removed. Use `wit.DecodeWIT(bytes.NewReader(b))` instead.
+
 ## [v0.4.0] — 2024-11-05
 
 This module has been renamed. Going forward, please use `go.bytecodealliance.org` instead of `github.com/bytecodealliance/wasm-tools-go`.

cmd/wit-bindgen-go/cmd/generate/generate.go

@@ -7,12 +7,13 @@ import (
 	"path/filepath"
 	"strings"
 
+	"github.com/urfave/cli/v3"
+
 	"go.bytecodealliance.org/internal/codec"
 	"go.bytecodealliance.org/internal/go/gen"
 	"go.bytecodealliance.org/internal/witcli"
 	"go.bytecodealliance.org/wit/bindgen"
 	"go.bytecodealliance.org/wit/logging"
-	"github.com/urfave/cli/v3"
 )
 
 // Command is the CLI command for wit.
@@ -80,12 +81,12 @@ type config struct {
 }
 
 func action(ctx context.Context, cmd *cli.Command) error {
-	cfg, err := parseFlags(cmd)
+	cfg, err := parseFlags(ctx, cmd)
 	if err != nil {
 		return err
 	}
 
-	res, err := witcli.LoadWIT(ctx, cfg.forceWIT, cfg.path)
+	res, err := witcli.LoadWIT(ctx, cfg.path, cmd.Reader, cfg.forceWIT)
 	if err != nil {
 		return err
 	}
@@ -102,10 +103,10 @@ func action(ctx context.Context, cmd *cli.Command) error {
 		return err
 	}
 
-	return writeGoPackages(packages, cfg)
+	return writeGoPackages(ctx, cmd, cfg, packages)
 }
 
-func parseFlags(cmd *cli.Command) (*config, error) {
+func parseFlags(_ context.Context, cmd *cli.Command) (*config, error) {
 	logger := witcli.Logger(cmd.Bool("verbose"), cmd.Bool("debug"))
 	dryRun := cmd.Bool("dry-run")
 	out := cmd.String("out")
@@ -145,7 +146,7 @@ func parseFlags(cmd *cli.Command) (*config, error) {
 	}, nil
 }
 
-func writeGoPackages(packages []*gen.Package, cfg *config) error {
+func writeGoPackages(_ context.Context, cmd *cli.Command, cfg *config, packages []*gen.Package) error {
 	cfg.logger.Infof("Generated %d Go package(s)\n", len(packages))
 	for _, pkg := range packages {
 		if !pkg.HasContent() {
@@ -179,8 +180,8 @@ func writeGoPackages(packages []*gen.Package, cfg *config) error {
 			}
 
 			if cfg.dryRun {
-				fmt.Println(string(content))
-				fmt.Println()
+				fmt.Fprintln(cmd.Writer, string(content))
+				fmt.Fprintln(cmd.Writer)
 				continue
 			}
 

cmd/wit-bindgen-go/cmd/wit/wit.go

@@ -4,9 +4,10 @@ import (
 	"context"
 	"fmt"
 
+	"github.com/urfave/cli/v3"
+
 	"go.bytecodealliance.org/internal/witcli"
 	"go.bytecodealliance.org/wit"
-	"github.com/urfave/cli/v3"
 )
 
 // Command is the CLI command for wit.
@@ -31,7 +32,7 @@ func action(ctx context.Context, cmd *cli.Command) error {
 	if err != nil {
 		return err
 	}
-	res, err := witcli.LoadWIT(ctx, cmd.Bool("force-wit"), path)
+	res, err := witcli.LoadWIT(ctx, path, cmd.Reader, cmd.Bool("force-wit"))
 	if err != nil {
 		return err
 	}

cmd/wit-bindgen-go/main.go

@@ -64,7 +64,7 @@ var version = &cli.Command{
 	Name:  "version",
 	Usage: "print the version",
 	Action: func(ctx context.Context, cmd *cli.Command) error {
-		fmt.Printf("%s version %s\n", cmd.Root().Name, witcli.Version())
+		fmt.Fprintf(cmd.Writer, "%s version %s\n", cmd.Root().Name, witcli.Version())
 		return nil
 	},
 }

cmd/wit-bindgen-go/main_test.go

@@ -3,14 +3,18 @@ package main
 import (
 	"bytes"
 	"context"
+	"strings"
 	"testing"
 )
 
 // TestSimpleGenVerbosity ensures that a basic generation case honors the verbose flag
 func TestSimpleGenVerbosity(t *testing.T) {
+	inWIT := `package tests:test;`
+	stdin := strings.NewReader(inWIT)
 	var stdout bytes.Buffer
 	var stderr bytes.Buffer
 	cmd := Command
+	cmd.Reader = stdin
 	cmd.Writer = &stdout
 	cmd.ErrWriter = &stderr
 
@@ -20,7 +24,7 @@ func TestSimpleGenVerbosity(t *testing.T) {
 		"--world",
 		"http-fetch-simple",
 		"--dry-run",
-		"../../testdata/codegen/simple-http.wit",
+		"-",
 	}
 
 	// Run the app without verbose
@@ -29,6 +33,7 @@ func TestSimpleGenVerbosity(t *testing.T) {
 		t.Errorf("output was written to stderr despite lack of --verbose")
 	}
 
+	stdin.Reset(inWIT)
 	stdout.Reset()
 	stderr.Reset()
 

internal/witcli/witcli.go

@@ -1,8 +1,10 @@
 package witcli
 
 import (
+	"bytes"
 	"context"
 	"fmt"
+	"io"
 	"os"
 	"strings"
 
@@ -17,18 +19,25 @@ import (
 // If the resolved path doesn’t end in ".json", it will attempt to load
 // WIT indirectly by processing the input through wasm-tools.
 // If forceWIT is true, it will always process input through wasm-tools.
-func LoadWIT(ctx context.Context, forceWIT bool, path string) (*wit.Resolve, error) {
+func LoadWIT(ctx context.Context, path string, r io.Reader, forceWIT bool) (*wit.Resolve, error) {
 	if oci.IsOCIPath(path) {
 		fmt.Fprintf(os.Stderr, "Fetching OCI artifact %s\n", path)
-		if bytes, err := oci.PullWIT(ctx, path); err != nil {
+		if b, err := oci.PullWIT(ctx, path); err != nil {
 			return nil, err
 		} else {
-			return wit.ParseWIT(bytes)
+			return wit.DecodeWIT(bytes.NewReader(b))
 		}
 	}
-	if forceWIT || (path != "" && path != "-" && !strings.HasSuffix(path, ".json")) {
+	forceReader := path == "" || path == "-"
+	if forceWIT || (!forceReader && !strings.HasSuffix(path, ".json")) {
+		if forceReader {
+			return wit.DecodeWIT(r)
+		}
 		return wit.LoadWIT(path)
 	}
+	if forceReader {
+		return wit.DecodeJSON(r)
+	}
 	return wit.LoadJSON(path)
 }
 

wit/load.go

@@ -10,14 +10,9 @@ import (
 )
 
 // LoadJSON loads a [WIT] JSON file from path.
-// If path is "" or "-", it reads from os.Stdin.
 //
 // [WIT]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/WIT.md
 func LoadJSON(path string) (*Resolve, error) {
-	r := reader(path)
-	if r != nil {
-		return DecodeJSON(r)
-	}
 	f, err := os.Open(path)
 	if err != nil {
 		return nil, err
@@ -28,22 +23,19 @@ func LoadJSON(path string) (*Resolve, error) {
 
 // LoadWIT loads [WIT] data from path by processing it through [wasm-tools].
 // This will fail if wasm-tools is not in $PATH.
-// If path is "" or "-", it reads from os.Stdin.
 //
 // [WIT]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/WIT.md
 // [wasm-tools]: https://crates.io/crates/wasm-tools
 func LoadWIT(path string) (*Resolve, error) {
-	r := reader(path)
-	return loadWIT(path, r)
+	return loadWIT(path, nil)
 }
 
-// ParseWIT parses [WIT] data from a buffer by processing it through [wasm-tools].
+// DecodeWIT decodes [WIT] data from Reader r by processing it through [wasm-tools].
 // This will fail if wasm-tools is not in $PATH.
 //
 // [WIT]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/WIT.md
 // [wasm-tools]: https://crates.io/crates/wasm-tools
-func ParseWIT(buffer []byte) (*Resolve, error) {
-	r := bytes.NewReader(buffer)
+func DecodeWIT(r io.Reader) (*Resolve, error) {
 	return loadWIT("", r)
 }
 
@@ -52,7 +44,7 @@ func ParseWIT(buffer []byte) (*Resolve, error) {
 // If the path is not "" and "-", it will be used as the input file.
 // Otherwise, the reader will be used as the input.
 func loadWIT(path string, reader io.Reader) (*Resolve, error) {
-	if (path != "" && path != "-") && reader != nil {
+	if path != "" && reader != nil {
 		return nil, errors.New("cannot set both path and reader; provide only one")
 	}
 
@@ -64,7 +56,7 @@ func loadWIT(path string, reader io.Reader) (*Resolve, error) {
 	var stdout, stderr bytes.Buffer
 
 	cmdArgs := []string{"component", "wit", "-j", "--all-features"}
-	if path != "" && path != "-" {
+	if path != "" {
 		cmdArgs = append(cmdArgs, path)
 	}
 
@@ -80,10 +72,3 @@ func loadWIT(path string, reader io.Reader) (*Resolve, error) {
 
 	return DecodeJSON(&stdout)
 }
-
-func reader(path string) io.ReadCloser {
-	if path == "" || path == "-" {
-		return os.Stdin
-	}
-	return nil
-}