cmd/shfmt: add initial EditorConfig support

Using the editorconfig module we've written over the past weeks.

See the README for a bit of docs on how it works. In particular, one can
entirely disable the feature by formatting stdin or using any formatting
flag.

We don't do any merging of flags from EditorConfig and the command line
right now; this keeps the implementation simple, and allows formatting
entire directories while skipping EditorConfig files with no-op flags
like "shfmt -ln=bash src/".

It's not clear that the ability to merge options from both sides would
be desirable; we might reconsider in the future.

We've also added an undocumented SHFMT_NO_EDITORCONFIG environment
variable, which can be set to "true" to completely disable the feature
in case it breaks badly when first released. This flag will be removed
once the feature has been released and stable for a few months.

Fixes #393.

README.md

@@ -48,6 +48,23 @@ Use `-i N` to indent with a number of spaces instead of tabs. There are other
 formatting options - see `shfmt -h`. For example, to get the formatting
 appropriate for [Google's Style][google-style] guide, use `shfmt -i 2 -ci`.
 
+If any [EditorConfig] files are found, they will be used to apply formatting
+options. If any parser or printer flags are given to the tool, or if the tool is
+formatting standard input, no EditorConfig files will be used. An example:
+
+```editorconfig
+[*.sh]
+# like -i=4
+indent_style = space
+indent_size = 4
+
+shell_variant      = posix # like -ln=posix
+binary_next_line   = true  # like -bn
+switch_case_indent = true  # like -ci
+space_redirects    = true  # like -sr
+keep_padding       = true  # like -kp
+```
+
 Packages are available on [Arch], [CRUX], [Docker], [FreeBSD], [Homebrew],
 [NixOS], [Scoop], [Snapcraft], and [Void].
 
@@ -132,6 +149,7 @@ To build a Docker image, checkout a specific version of the repository and run:
 [docker]: https://hub.docker.com/r/mvdan/shfmt/
 [dockerized-jamesmstone]: https://hub.docker.com/r/jamesmstone/shfmt/
 [dockerized-peterdavehello]: https://github.com/PeterDaveHello/dockerized-shfmt/
+[editorconfig]: https://editorconfig.org/
 [examples]: https://godoc.org/mvdan.cc/sh/syntax#pkg-examples
 [format-shell]: https://atom.io/packages/format-shell
 [freebsd]: https://github.com/freebsd/freebsd-ports/tree/HEAD/devel/shfmt

cmd/shfmt/main.go

@@ -16,6 +16,7 @@ import (
 
 	"github.com/pkg/diff"
 	"golang.org/x/crypto/ssh/terminal"
+	"mvdan.cc/editorconfig"
 
 	"mvdan.cc/sh/v3/fileutil"
 	"mvdan.cc/sh/v3/syntax"
@@ -27,9 +28,13 @@ var (
 	list    = flag.Bool("l", false, "")
 	write   = flag.Bool("w", false, "")
 	simple  = flag.Bool("s", false, "")
+	minify  = flag.Bool("mn", false, "")
 	find    = flag.Bool("f", false, "")
 	diffOut = flag.Bool("d", false, "")
 
+	// useEditorConfig will be false if any parser or printer flags were used.
+	useEditorConfig = true
+
 	langStr = flag.String("ln", "", "")
 	posix   = flag.Bool("p", false, "")
 
@@ -38,7 +43,6 @@ var (
 	caseIndent  = flag.Bool("ci", false, "")
 	spaceRedirs = flag.Bool("sr", false, "")
 	keepPadding = flag.Bool("kp", false, "")
-	minify      = flag.Bool("mn", false, "")
 
 	toJSON = flag.Bool("tojson", false, "")
 
@@ -73,6 +77,7 @@ by filename extension and by shebang.
   -w        write result to file instead of stdout
   -d        error with a diff when the formatting differs
   -s        simplify the code
+  -mn       minify the code to reduce its size (implies -s)
 
 Parser options:
 
@@ -86,7 +91,6 @@ Printer options:
   -ci       switch cases will be indented
   -sr       redirect operators will be followed by a space
   -kp       keep column alignment paddings
-  -mn       minify program to reduce its size (implies -s)
 
 Utilities:
 
@@ -104,32 +108,45 @@ Utilities:
 		fmt.Fprintf(os.Stderr, "-p and -ln=lang cannot coexist\n")
 		return 1
 	}
-	lang := syntax.LangBash
-	switch *langStr {
-	case "bash", "":
-	case "posix":
-		lang = syntax.LangPOSIX
-	case "mksh":
-		lang = syntax.LangMirBSDKorn
-	default:
-		fmt.Fprintf(os.Stderr, "unknown shell language: %s\n", *langStr)
-		return 1
-	}
-	if *posix {
-		lang = syntax.LangPOSIX
-	}
 	if *minify {
 		*simple = true
 	}
-	parser = syntax.NewParser(syntax.KeepComments(true), syntax.Variant(lang))
-	printer = syntax.NewPrinter(
-		syntax.Indent(*indent),
-		syntax.BinaryNextLine(*binNext),
-		syntax.SwitchCaseIndent(*caseIndent),
-		syntax.SpaceRedirects(*spaceRedirs),
-		syntax.KeepPadding(*keepPadding),
-		syntax.Minify(*minify),
-	)
+	if os.Getenv("SHFMT_NO_EDITORCONFIG") == "true" {
+		useEditorConfig = false
+	}
+	flag.Visit(func(f *flag.Flag) {
+		switch f.Name {
+		case "ln", "p", "i", "bn", "ci", "sr", "kp":
+			useEditorConfig = false
+		}
+	})
+	parser = syntax.NewParser(syntax.KeepComments(true))
+	printer = syntax.NewPrinter(syntax.Minify(*minify))
+
+	lang := syntax.LangBash
+	if !useEditorConfig {
+		switch *langStr {
+		case "bash", "":
+		case "posix":
+			lang = syntax.LangPOSIX
+		case "mksh":
+			lang = syntax.LangMirBSDKorn
+		default:
+			fmt.Fprintf(os.Stderr, "unknown shell language: %s\n", *langStr)
+			return 1
+		}
+		if *posix {
+			lang = syntax.LangPOSIX
+		}
+		syntax.Variant(lang)(parser)
+
+		syntax.Indent(*indent)(printer)
+		syntax.BinaryNextLine(*binNext)(printer)
+		syntax.SwitchCaseIndent(*caseIndent)(printer)
+		syntax.SpaceRedirects(*spaceRedirs)(printer)
+		syntax.KeepPadding(*keepPadding)(printer)
+	}
+
 	if os.Getenv("FORCE_COLOR") == "true" {
 		// Undocumented way to force color; used in the tests.
 		color = true
@@ -210,11 +227,48 @@ func walk(path string, onError func(error)) {
 	})
 }
 
+var query = editorconfig.Query{
+	FileCache:   make(map[string]*editorconfig.File),
+	RegexpCache: make(map[string]*regexp.Regexp),
+}
+
+func propsOptions(props editorconfig.Section) {
+	lang := syntax.LangBash
+	switch props.Get("shell_variant") {
+	case "posix":
+		lang = syntax.LangPOSIX
+	case "mksh":
+		lang = syntax.LangMirBSDKorn
+	}
+	syntax.Variant(lang)(parser)
+
+	size := uint(0)
+	if props.Get("indent_style") == "space" {
+		size = 8
+		if n := props.IndentSize(); n > 0 {
+			size = uint(n)
+		}
+	}
+	syntax.Indent(size)(printer)
+
+	syntax.BinaryNextLine(props.Get("binary_next_line") == "true")(printer)
+	syntax.SwitchCaseIndent(props.Get("switch_case_indent") == "true")(printer)
+	syntax.SpaceRedirects(props.Get("space_redirects") == "true")(printer)
+	syntax.KeepPadding(props.Get("keep_padding") == "true")(printer)
+}
+
 func formatPath(path string, checkShebang bool) error {
 	f, err := os.Open(path)
 	if err != nil {
 		return err
 	}
+	if useEditorConfig {
+		props, err := query.Find(path)
+		if err != nil {
+			return err
+		}
+		propsOptions(props)
+	}
 	defer f.Close()
 	readBuf.Reset()
 	if checkShebang {

cmd/shfmt/testdata/scripts/editorconfig.txt

@@ -0,0 +1,109 @@
+cp input.sh input.sh.orig
+
+# Using stdin should ignore the EditorConfig file.
+stdin input.sh
+shfmt
+cmp stdout input.sh.orig
+! stderr .
+
+# Using a file path should use EditorConfig, including with the use of flags
+# like -l.
+shfmt input.sh
+cmp stdout input.sh.golden
+! stderr .
+
+shfmt -l input.sh
+stdout 'input\.sh'
+! stderr .
+
+# Using any formatting option should skip all EditorConfig usage.
+shfmt -p input.sh
+cmp stdout input.sh.orig
+! stderr .
+
+shfmt -l -p input.sh
+! stdout .
+! stderr .
+
+shfmt -sr input.sh
+cmp stdout input.sh.orig
+! stderr .
+
+# Check that EditorConfig files merge properly.
+shfmt morespaces/input.sh
+cmp stdout morespaces/input.sh.golden
+! stderr .
+
+# Check a folder with all other knobs.
+shfmt -l otherknobs
+! stdout .
+! stderr .
+
+-- .editorconfig --
+root = true
+
+[*]
+indent_style = space
+indent_size = 3
+-- input.sh --
+{
+	indented
+}
+-- input.sh.golden --
+{
+   indented
+}
+-- morespaces/.editorconfig --
+[*.sh]
+indent_size = 6
+-- morespaces/input.sh --
+{
+	indented
+}
+-- morespaces/input.sh.golden --
+{
+      indented
+}
+-- otherknobs/.editorconfig --
+root = true
+
+[shell_variant_posix.sh]
+shell_variant = posix
+
+[shell_variant_mksh.sh]
+shell_variant = mksh
+
+[indent.sh]
+# check its default; we tested "space" above.
+
+[binary_next_line.sh]
+binary_next_line = true
+
+[switch_case_indent.sh]
+switch_case_indent = true
+
+[space_redirects.sh]
+space_redirects = true
+
+[keep_padding.sh]
+keep_padding = true
+
+-- otherknobs/shell_variant_posix.sh --
+let badsyntax+
+-- otherknobs/shell_variant_mksh.sh --
+coproess |&
+-- otherknobs/indent.sh --
+{
+	indented
+}
+-- otherknobs/binary_next_line.sh --
+foo \
+	| bar
+-- otherknobs/switch_case_indent.sh --
+case "$1" in
+	A) echo foo ;;
+esac
+-- otherknobs/space_redirects.sh --
+echo foo > bar
+-- otherknobs/keep_padding.sh --
+echo  foo    bar

cmd/shfmt/testdata/scripts/flags.txt

@@ -17,3 +17,18 @@ stderr 'unknown shell language'
 
 ! shfmt -tojson file
 stderr 'can only be used with stdin'
+
+# Check all the -ln variations.
+stdin notbash.sh
+! shfmt
+stdin notbash.sh
+shfmt -ln=posix
+stdin notbash.sh
+shfmt -p
+stdin notbash.sh
+! shfmt -ln=mksh
+stdin notbash.sh
+! shfmt -ln=bash
+
+-- notbash.sh --
+let a+

go.mod

@@ -12,4 +12,5 @@ require (
 	golang.org/x/sys v0.0.0-20191008105621-543471e840be // indirect
 	golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898
 	gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 // indirect
+	mvdan.cc/editorconfig v0.1.1-0.20191109213504-890940e3f00e
 )

go.sum

@@ -39,3 +39,7 @@ gopkg.in/errgo.v2 v2.1.0 h1:0vLT13EuvQ0hNvakwLuFZ/jYrLp5F3kcWHXdRggjCE8=
 gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
 gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+mvdan.cc/editorconfig v0.1.0 h1:ScBDwl2i6CBDzPFtKUB7dnp/y6lh2aCxmTU5LO3OX4M=
+mvdan.cc/editorconfig v0.1.0/go.mod h1:Ge4atmRUYqueGppvJ7JNrtqpqokoJEFxYbP0Z+WeKS8=
+mvdan.cc/editorconfig v0.1.1-0.20191109213504-890940e3f00e h1:mpgBTmbRe4vLIQIWTPipFCM2P97pEnkFSthekRyxqfY=
+mvdan.cc/editorconfig v0.1.1-0.20191109213504-890940e3f00e/go.mod h1:Ge4atmRUYqueGppvJ7JNrtqpqokoJEFxYbP0Z+WeKS8=