Add dart formatter with CLIs or goja

Author: tsuzu

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2022 go-generalize
+
+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.

cli.go

@@ -0,0 +1,64 @@
+package dartfmt
+
+import (
+	"bytes"
+	"fmt"
+	"os/exec"
+	"strings"
+)
+
+func runCLI(script string, name string, arg ...string) (string, error) {
+	cmd := exec.Command(name, arg...)
+	cmd.Stdin = strings.NewReader(script)
+
+	stdout, stderr := bytes.Buffer{}, bytes.Buffer{}
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+
+	if err := cmd.Start(); err != nil {
+		return "", unavailableError{err: err}
+	}
+
+	if err := cmd.Wait(); err != nil {
+		return "", fmt.Errorf(
+			"formatter failed(%s): %w",
+			stdout.String()+"\n"+stderr.String(),
+			err,
+		)
+	}
+
+	return stdout.String(), nil
+}
+
+// FormatDartWithDartCLI formats a script with `dart format`
+func FormatDartWithDartCLI(script string) (string, error) {
+	formatted, err := runCLI(script, "dart", "format")
+
+	if err != nil {
+		return "", fmt.Errorf("formatting with `dart format` failed: %w", err)
+	}
+
+	return formatted, nil
+}
+
+// FormatDartWithDartfmtCLI formats a script with `dartfmt`
+func FormatDartWithDartfmtCLI(script string) (string, error) {
+	formatted, err := runCLI(script, "dartfmt")
+
+	if err != nil {
+		return "", fmt.Errorf("formatting with `dartfmt` failed: %w", err)
+	}
+
+	return formatted, nil
+}
+
+// FormatDartWithFlutterCLI formats a script with `flutter format`
+func FormatDartWithFlutterCLI(script string) (string, error) {
+	formatted, err := runCLI(script, "flutter", "format")
+
+	if err != nil {
+		return "", fmt.Errorf("formatting with `flutter format` failed: %w", err)
+	}
+
+	return formatted, nil
+}

dartfmt.go

@@ -0,0 +1,37 @@
+package dartfmt
+
+import (
+	_ "embed"
+	"errors"
+	"fmt"
+)
+
+// Formatter is a type of dart formatters
+type Formatter func(script string) (string, error)
+
+// Formatters are candidates for FormatDart
+var Formatters = []Formatter{
+	FormatDartWithFlutterCLI,
+	FormatDartWithDartCLI,
+	FormatDartWithDartfmtCLI,
+	FormatDartStandalone,
+}
+
+// FormatDart tries to format a script with all of Formatters one-by-one
+func FormatDart(script string) (string, error) {
+	for _, fmtr := range Formatters {
+		formatted, err := fmtr(script)
+
+		if err != nil {
+			if errors.As(err, &unavailableError{}) {
+				continue
+			}
+
+			return "", fmt.Errorf("formatting failed: %w", err)
+		}
+
+		return formatted, nil
+	}
+
+	return "", fmt.Errorf("no available formatter")
+}

dartfmt_test.go

@@ -0,0 +1,41 @@
+package dartfmt_test
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/go-generalize/go-dartfmt"
+	"github.com/google/go-cmp/cmp"
+)
+
+func runFormat(t *testing.T, formatter dartfmt.Formatter, dir string) {
+	t.Helper()
+
+	input, err := os.ReadFile(filepath.Join(dir, "input.dart"))
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expectedBytes, err := os.ReadFile(filepath.Join(dir, "output.dart"))
+
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := string(expectedBytes)
+
+	actual, err := dartfmt.FormatDart(string(input))
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if diff := cmp.Diff(expected, actual); diff != "" {
+		t.Errorf("the result differed: %s", diff)
+	}
+}
+
+func TestDartFormat(t *testing.T) {
+	runFormat(t, dartfmt.FormatDart, "testdata/001")
+}

error.go

@@ -0,0 +1,19 @@
+package dartfmt
+
+type unavailableError struct {
+	err error
+}
+
+var _ error = unavailableError{}
+
+func (e unavailableError) Error() string {
+	return e.err.Error()
+}
+
+func (e unavailableError) Unwrap() error {
+	return e.err
+}
+
+func (e unavailableError) Is(target error) bool {
+	return target == e.err
+}

go.mod

@@ -0,0 +1,15 @@
+module github.com/go-generalize/go-dartfmt
+
+go 1.17
+
+require (
+	github.com/dop251/goja v0.0.0-20220104154337-b93494d0c5d9
+	github.com/google/go-cmp v0.5.6
+	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c
+)
+
+require (
+	github.com/dlclark/regexp2 v1.4.1-0.20201116162257-a2a8dda75c91 // indirect
+	github.com/go-sourcemap/sourcemap v2.1.3+incompatible // indirect
+	golang.org/x/text v0.3.6 // indirect
+)

go.sum

@@ -0,0 +1,25 @@
+github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/dlclark/regexp2 v1.4.1-0.20201116162257-a2a8dda75c91 h1:Izz0+t1Z5nI16/II7vuEo/nHjodOg0p7+OiDpjX5t1E=
+github.com/dlclark/regexp2 v1.4.1-0.20201116162257-a2a8dda75c91/go.mod h1:2pZnwuY/m+8K6iRw6wQdMtk+rH5tNGR1i55kozfMjCc=
+github.com/dop251/goja v0.0.0-20220104154337-b93494d0c5d9 h1:QYh60R7QllMj/JKMtE2hCrwRqDbQq8vsUD63SDdVpHw=
+github.com/dop251/goja v0.0.0-20220104154337-b93494d0c5d9/go.mod h1:R9ET47fwRVRPZnOGvHxxhuZcbrMCuiqOz3Rlrh4KSnk=
+github.com/dop251/goja_nodejs v0.0.0-20210225215109-d91c329300e7/go.mod h1:hn7BA7c8pLvoGndExHudxTDKZ84Pyvv+90pbBjbTz0Y=
+github.com/go-sourcemap/sourcemap v2.1.3+incompatible h1:W1iEw64niKVGogNgBN3ePyLFfuisuzeidWPMPWmECqU=
+github.com/go-sourcemap/sourcemap v2.1.3+incompatible/go.mod h1:F8jJfvm2KbVjc5NqelyYJmf/v5J0dwNLS2mL4sNA1Jg=
+github.com/google/go-cmp v0.5.6 h1:BKbKCqvP6I+rmFHt06ZmyQtvB8xAkWdhFyr0ZUNZcxQ=
+github.com/google/go-cmp v0.5.6/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
+github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c h1:5KslGYwFpkhGh+Q16bwMP3cOontH8FOep7tGV86Y7SQ=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/text v0.3.6 h1:aRYxNxv6iGQlyVaZmk6ZgYEDa+Jg18DxebPSrd6bg1M=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
+gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
+gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=

goja.go

@@ -0,0 +1,86 @@
+package dartfmt
+
+import (
+	_ "embed"
+	"fmt"
+	"sync"
+
+	"github.com/dop251/goja"
+	"github.com/dop251/goja/parser"
+	"golang.org/x/sync/singleflight"
+)
+
+//go:embed internal/entrypoint/dist/entrypoint.js
+var formatScript string
+var formatProgram *goja.Program
+
+const formatScriptFormat = `
+var self = {location: {href: '/'}};
+%s
+var formatDart = self.formatDart;
+`
+
+func compileFormatterForSingleflight() (interface{}, error) {
+	if formatProgram != nil {
+		return formatProgram, nil
+	}
+
+	prog, err := goja.Parse(
+		"entrypoint.js",
+		fmt.Sprintf(formatScriptFormat, formatScript),
+		parser.WithDisableSourceMaps,
+	)
+
+	if err != nil {
+		return nil, fmt.Errorf("parsing a script failed: %w", err)
+	}
+
+	formatProgram, err = goja.CompileAST(prog, false)
+
+	if err != nil {
+		return nil, fmt.Errorf("compiling AST failed: %w", err)
+	}
+
+	return formatProgram, nil
+}
+
+var group singleflight.Group
+var pool = sync.Pool{
+	New: func() interface{} {
+		fg, err, _ := group.Do("entrypoint.js", compileFormatterForSingleflight)
+
+		if err != nil {
+			panic(err)
+		}
+
+		vm := goja.New()
+
+		_, err = vm.RunProgram(fg.(*goja.Program))
+
+		if err != nil {
+			panic(err)
+		}
+
+		return vm
+	},
+}
+
+// FormatDartStandalone formats a script without dependencies on external commands
+func FormatDartStandalone(script string) (string, error) {
+	vm := pool.Get().(*goja.Runtime)
+	defer pool.Put(vm)
+
+	dartFormat := vm.GlobalObject().Get("formatDart")
+
+	if dartFormat == nil {
+		return "", fmt.Errorf("formatDart is nil")
+	}
+
+	var fn func(string) string
+	err := vm.ExportTo(dartFormat, &fn)
+	if err != nil {
+		return "", fmt.Errorf("failed to execute dart_style formatter: %w", err)
+	}
+
+	return fn(script), nil
+}

internal/entrypoint/.gitignore

@@ -0,0 +1,9 @@
+# Files and directories created by pub
+.dart_tool/
+.packages
+
+# Conventional directory for build outputs
+build/
+
+# Directory created by dartdoc
+doc/api/

internal/entrypoint/Makefile

@@ -0,0 +1,6 @@
+.PHONY: init build
+init:
+	dart pub get
+
+build:
+	dart2js -O2 -o dist/entrypoint.js bin/entrypoint.dart