Feature/implement formatter

.gitignore

@@ -27,3 +27,6 @@ __generator__/*.csv
 debugger.log
 debug.log
 request.json
+
+.falco.yml
+.falco.yaml

README.md

@@ -66,6 +66,8 @@ Subcommands:
     stats     : Analyze VCL statistics
     simulate  : Run simulator server with provided VCLs
     test      : Run local testing for provided VCLs
+    fmt       : Run formatter for provided VCLs
+
 
 See subcommands help with:
     falco [subcommand] -h
@@ -93,6 +95,14 @@ that you improve your VCL more robustly by passing the linter.
 
 See [linter documentation](https://github.com/ysugimoto/falco/blob/main/docs/linter.md) in detail.
 
+## Formatter
+
+Format provided VCL by our recommended styles.
+Currently we have a few options to control formatting style like [biomejs](https://github.com/biomejs/biome).
+Through the formatter, your VCL codes have unified format even multiple people are maintaining VCL.
+
+See [formatter documentation](./docs/formatter.md) in detail.
+
 ## Local Simulator / VCL Debugger
 
 `falco` has self-implemented interpreter for running VCL program locally.

ast/ast.go

@@ -27,11 +27,12 @@ type Expression interface {
 
 // Meta struct of all nodes
 type Meta struct {
-	Token    token.Token
-	Leading  Comments
-	Trailing Comments
-	Infix    Comments
-	Nest     int
+	Token              token.Token
+	Leading            Comments
+	Trailing           Comments
+	Infix              Comments
+	Nest               int
+	PreviousEmptyLines int
 }
 
 func (m *Meta) LeadingComment() string {

ast/comment.go

@@ -23,7 +23,8 @@ type Comment struct {
 	// If this flag is false, it should be treated as trailing comment
 	// because the comment presents on the same line.
 	// Otherwise, this flag is true, it should be the leading comment for a next token.
-	PrefixedLineFeed bool
+	PrefixedLineFeed   bool
+	PreviousEmptyLines int
 }
 
 func (c *Comment) String() string {

ast/if_statement.go

@@ -6,6 +6,7 @@ import (
 
 type IfStatement struct {
 	*Meta
+	Keyword             string
 	Condition           Expression
 	Consequence         *BlockStatement
 	Another             []*IfStatement
@@ -19,15 +20,15 @@ func (i *IfStatement) String() string {
 	var buf bytes.Buffer
 
 	buf.WriteString(i.LeadingComment())
-	buf.WriteString(indent(i.Nest) + "if (")
+	buf.WriteString(indent(i.Nest) + i.Keyword + " (")
 	buf.WriteString(i.Condition.String())
 	buf.WriteString(") ")
 	buf.WriteString(i.Consequence.String())
 
 	for _, a := range i.Another {
 		buf.WriteString("\n")
 		buf.WriteString(a.LeadingComment())
-		buf.WriteString(indent(i.Nest) + "else if (")
+		buf.WriteString(indent(i.Nest) + a.Keyword + " (")
 		buf.WriteString(a.Condition.String())
 		buf.WriteString(") ")
 		buf.WriteString(a.Consequence.String())

ast/if_statement_test.go

@@ -6,14 +6,16 @@ import (
 
 func TestIfStatement(t *testing.T) {
 	ifs := &IfStatement{
-		Meta: New(T, 0, comments("// This is comment"), comments("/* This is comment */")),
+		Keyword: "if",
+		Meta:    New(T, 0, comments("// This is comment"), comments("/* This is comment */")),
 		Condition: &Ident{
 			Meta:  New(T, 0),
 			Value: "req.http.Host",
 		},
 		Another: []*IfStatement{
 			{
-				Meta: New(T, 0, comments("// This is comment"), comments("/* This is comment */")),
+				Keyword: "else if",
+				Meta:    New(T, 0, comments("// This is comment"), comments("/* This is comment */")),
 				Condition: &Ident{
 					Meta:  New(T, 0),
 					Value: "req.http.Host",

cmd/falco/help.go

@@ -17,6 +17,8 @@ func printHelp(cmd string) {
 		printTestHelp()
 	case subcommandLint:
 		printLintHelp()
+	case subcommandFormat:
+		printFormatHelp()
 	default:
 		printGlobalHelp()
 	}
@@ -46,6 +48,7 @@ Subcommands:
     stats     : Analyze VCL statistics
     simulate  : Run simulator server with provided VCLs
     test      : Run local testing for provided VCLs
+    fmt       : Run formatter for provided VCLs
 
 See subcommands help with:
     falco [subcommand] -h
@@ -91,7 +94,7 @@ Linting with terraform:
 func printSimulateHelp() {
 	writeln(white, strings.TrimSpace(`
 Usage:
-    falco simulate [flags]
+    falco simulate [flags] file
 
 Flags:
     -I, --include_path : Add include path
@@ -113,7 +116,7 @@ Local debugger example:
 func printStatsHelp() {
 	writeln(white, strings.TrimSpace(`
 Usage:
-    falco stats [flags]
+    falco stats [flags] file
 
 Flags:
     -I, --include_path : Add include path
@@ -150,13 +153,12 @@ Local testing example:
 func printLintHelp() {
 	writeln(white, strings.TrimSpace(`
 Usage:
-    falco lint [flags]
+    falco lint [flags] file
 
 Flags:
     -I, --include_path : Add include path
     -h, --help         : Show this help
     -r, --remote       : Connect with Fastly API
-    -V, --version      : Display build version
     -v                 : Output lint warnings (verbose)
     -vv                : Output all lint results (very verbose)
     -json              : Output results as JSON (very verbose)
@@ -165,3 +167,19 @@ Simple linting with very verbose example:
     falco lint -I . -vv /path/to/vcl/main.vcl
 	`))
 }
+
+func printFormatHelp() {
+	writeln(white, strings.TrimSpace(`
+Usage:
+    falco fmt [flags] ...files
+
+Flags:
+    -h, --help         : Show this help
+    -w, --write        : Overwrite format result
+
+files argument accepts glob file patterns
+
+Simple format example:
+    falco fmt /path/to/vcl/main.vcl
+	`))
+}

cmd/falco/main.go

@@ -51,6 +51,7 @@ const (
 	subcommandSimulate  = "simulate"
 	subcommandStats     = "stats"
 	subcommandTest      = "test"
+	subcommandFormat    = "fmt"
 )
 
 func write(c *color.Color, format string, args ...interface{}) {
@@ -88,10 +89,17 @@ func main() {
 		}
 		action = c.Commands.At(1)
 	case subcommandSimulate, subcommandLint, subcommandStats, subcommandTest:
-		// "lint", "simulate", "stats" and "test" command provides single file of service,
+		// "lint", "simulate", "stats", and "test" command provides single file of service,
 		// then resolvers size is always 1
 		resolvers, err = resolver.NewFileResolvers(c.Commands.At(1), c.IncludePaths)
 		action = c.Commands.At(0)
+	case subcommandFormat:
+		// "fmt" command accepts multiple target files
+		resolvers, err = resolver.NewGlobResolver(c.Commands[1:]...)
+		action = c.Commands.At(0)
+		if len(resolvers) == 0 {
+			err = fmt.Errorf("No input files speficied")
+		}
 	case "":
 		printHelp("")
 		os.Exit(1)
@@ -105,7 +113,8 @@ func main() {
 		}
 	}
 
-	if c.Remote {
+	// No need to use remove object on fmt command
+	if action != subcommandFormat && c.Remote {
 		if !c.Json {
 			writeln(cyan, "Remote option supplied. Fetching snippets from Fastly.")
 		}
@@ -154,6 +163,8 @@ func main() {
 			exitErr = runSimulate(runner, v)
 		case subcommandStats:
 			exitErr = runStats(runner, v)
+		case subcommandFormat:
+			exitErr = runFormat(runner, v)
 		default:
 			exitErr = runLint(runner, v)
 		}
@@ -377,3 +388,13 @@ func runTest(runner *Runner, rslv resolver.Resolver) error {
 		return nil
 	}
 }
+
+func runFormat(runner *Runner, rslv resolver.Resolver) error {
+	if err := runner.Format(rslv); err != nil {
+		if err != ErrParser {
+			writeln(red, err.Error())
+		}
+		return ErrExit
+	}
+	return nil
+}

cmd/falco/runner.go

@@ -3,7 +3,9 @@ package main
 import (
 	"bytes"
 	"fmt"
+	"io"
 	"net/http"
+	"os"
 	"strings"
 
 	"github.com/fatih/color"
@@ -12,6 +14,7 @@ import (
 	"github.com/ysugimoto/falco/config"
 	"github.com/ysugimoto/falco/context"
 	"github.com/ysugimoto/falco/debugger"
+	"github.com/ysugimoto/falco/formatter"
 	"github.com/ysugimoto/falco/interpreter"
 	icontext "github.com/ysugimoto/falco/interpreter/context"
 	"github.com/ysugimoto/falco/lexer"
@@ -485,3 +488,32 @@ func (r *Runner) Test(rslv resolver.Resolver) (*tester.TestFactory, error) {
 	r.message(white, " Done.\n")
 	return factory, nil
 }
+
+func (r *Runner) Format(rslv resolver.Resolver) error {
+	main, err := rslv.MainVCL()
+	if err != nil {
+		return err
+	}
+	vcl, err := r.parseVCL(main.Name, main.Data)
+	if err != nil {
+		return err
+	}
+
+	formatted := formatter.New(r.config.Format).Format(vcl)
+	var w io.Writer
+	if r.config.Format.Overwrite {
+		writeln(cyan, "Formatted %s.", main.Name)
+		fp, err := os.OpenFile(main.Name, os.O_TRUNC|os.O_WRONLY, 0o644)
+		if err != nil {
+			return errors.WithStack(err)
+		}
+		defer fp.Close()
+		w = fp
+	} else {
+		w = os.Stdout
+	}
+	if _, err := io.Copy(w, formatted); err != nil {
+		return err
+	}
+	return nil
+}

config/config.go

@@ -12,6 +12,15 @@ var (
 	configurationFiles = []string{".falco.yaml", ".falco.yml"}
 )
 
+// Formatting value constants
+const (
+	IndentStyleSpace  = "space"
+	IndentStyleTab    = "tab"
+	CommentStyleNone  = "none"
+	CommentStyleSlash = "slash"
+	CommentStyleSharp = "sharp"
+)
+
 type OverrideBackend struct {
 	Host      string `yaml:"host"`
 	SSL       bool   `yaml:"ssl" default:"true"`
@@ -47,6 +56,28 @@ type TestConfig struct {
 	OverrideRequest *RequestConfig
 }
 
+// Format configuration
+type FormatConfig struct {
+	// CLI options
+	Overwrite bool `cli:"w,write" default:"false"`
+
+	// Formatter options
+	IndentWidth                int    `yaml:"indent_width" default:"2"`
+	TrailingCommentWidth       int    `yaml:"trailing_comment_width" default:"2"`
+	IndentStyle                string `yaml:"indent_style" default:"space"`
+	LineWidth                  int    `yaml:"line_width" default:"120"`
+	ExplicitStringConat        bool   `yaml:"explicit_string_concat" default:"false"`
+	SortDeclarationProperty    bool   `yaml:"sort_declaration_property" default:"false"`
+	AlignDeclarationProperty   bool   `yaml:"align_declaration_property" default:"false"`
+	ElseIf                     bool   `yaml:"else_if" default:"false"`
+	AlwaysNextLineElseIf       bool   `yaml:"always_next_line_else_if" default:"false"`
+	ReturnStatementParenthesis bool   `yaml:"return_statement_parenthesis" default:"true"`
+	SortDeclaration            bool   `yaml:"sort_declaration" defaul:"false"`
+	AlignTrailingComment       bool   `yaml:"align_trailing_comment" default:"false"`
+	CommentStyle               string `yaml:"comment_style" default:"none"`
+	ShouldUseUnset             bool   `yaml:"should_use_unset" default:"false"`
+}
+
 type Config struct {
 	// Root configurations
 	IncludePaths []string `cli:"I,include_path" yaml:"include_paths"`
@@ -77,6 +108,8 @@ type Config struct {
 	Simulator *SimulatorConfig `yaml:"simulator"`
 	// Testing configuration
 	Testing *TestConfig `yaml:"testing"`
+	// Format configuration
+	Format *FormatConfig `yaml:"format"`
 }
 
 func New(args []string) (*Config, error) {
@@ -92,12 +125,6 @@ func New(args []string) (*Config, error) {
 
 	c := &Config{
 		OverrideBackends: make(map[string]*OverrideBackend),
-		// Simulator: &SimulatorConfig{
-		// 	OverrideRequest:  &RequestConfig{},
-		// },
-		// Testing: &TestConfig{
-		// 	OverrideRequest: &RequestConfig{},
-		// },
 	}
 	if err := twist.Mix(c, options...); err != nil {
 		return nil, errors.WithStack(err)

config/config_test.go

@@ -63,6 +63,21 @@ func TestConfigFromCLI(t *testing.T) {
 			IncludePaths:    []string{"."},
 			OverrideRequest: &RequestConfig{},
 		},
+		Format: &FormatConfig{
+			IndentWidth:                2,
+			TrailingCommentWidth:       2,
+			LineWidth:                  120,
+			IndentStyle:                "space",
+			ExplicitStringConat:        false,
+			SortDeclarationProperty:    false,
+			AlignDeclarationProperty:   false,
+			ElseIf:                     false,
+			ReturnStatementParenthesis: true,
+			SortDeclaration:            false,
+			AlignTrailingComment:       false,
+			CommentStyle:               "none",
+			ShouldUseUnset:             false,
+		},
 		OverrideBackends: make(map[string]*OverrideBackend),
 	}