remove multiline AST rendering for now, add Rudi renderer to turn AST back into Rudi code (closes #10)

Author: xrstf

cmd/rudi/cmd/script/command.go

@@ -15,7 +15,6 @@ import (
 	"go.xrstf.de/rudi/cmd/rudi/options"
 	"go.xrstf.de/rudi/cmd/rudi/types"
 	"go.xrstf.de/rudi/cmd/rudi/util"
-	"go.xrstf.de/rudi/pkg/printer"
 
 	"github.com/BurntSushi/toml"
 	"gopkg.in/yaml.v3"
@@ -55,8 +54,7 @@ func Run(handler *util.SignalHandler, opts *options.Options, args []string) erro
 
 	// show AST and quit if desired
 	if opts.PrintAst {
-		renderer := printer.AST{}
-		if err := renderer.WriteMultiline(program, os.Stdout); err != nil {
+		if err := program.DumpSyntaxTree(os.Stdout); err != nil {
 			return fmt.Errorf("failed to dump AST: %w", err)
 		}
 

pkg/lang/ast/types.go

@@ -5,9 +5,20 @@ package ast
 
 import (
 	"fmt"
+	"regexp"
 	"strings"
 )
 
+// These variables must manually be kept in-sync with the Rudi grammar.
+// Hoping that https://github.com/mna/pigeon/issues/141 will provide us with a better way.
+// Compared to the original grammar, these regex are anchored to make matching easier.
+
+var (
+	VariableNamePattern   = regexp.MustCompile(`^[a-zA-Z_][a-zA-Z0-9_]*$`)
+	PathIdentifierPattern = VariableNamePattern
+	IdentifierNamePattern = regexp.MustCompile(`^[a-zA-Z_+/*_%?-][a-zA-Z0-9_+/*_%?!-]*$`)
+)
+
 type Expression interface {
 	String() string
 	ExpressionName() string
@@ -408,7 +419,11 @@ type EvaluatedPathStep struct {
 func (a EvaluatedPathStep) String() string {
 	switch {
 	case a.StringValue != nil:
-		return fmt.Sprintf("[%q]", *a.StringValue)
+		if PathIdentifierPattern.MatchString(*a.StringValue) {
+			return fmt.Sprintf(".%s", *a.StringValue)
+		} else {
+			return fmt.Sprintf("[%q]", *a.StringValue)
+		}
 	case a.IntegerValue != nil:
 		return fmt.Sprintf("[%d]", *a.IntegerValue)
 	default:

pkg/lang/grammar/rudi.peg

@@ -249,10 +249,11 @@ ObjectAccessor <- '.' val:PathIdentifier {
    return val, nil
 }
 
-VectorAccessor <- '[' expr:ScalarExpression ']' {
+VectorAccessor <- '[' __ expr:ScalarExpression __ ']' {
    return expr, nil
 }
 
+// This Pattern must be kept in-sync with the PathIdentifierPattern variable in the ast package.
 PathIdentifier <- [a-zA-Z_][a-zA-Z0-9_]* {
    return ast.Identifier{Name: string(c.text)}, nil
 }
@@ -264,10 +265,12 @@ Variable <- '$' name:VariableName {
    return ast.Variable(name.(string)), nil
 }
 
+// This Pattern must be kept in-sync with the VariableNamePattern variable in the ast package.
 VariableName <- [a-zA-Z_][a-zA-Z0-9_]* {
    return string(c.text), nil
 }
 
+// This Pattern must be kept in-sync with the IdentifierNamePattern variable in the ast package.
 Identifier <- [a-zA-Z_+/*_%?-][a-zA-Z0-9_+/*_%?!-]* {
    name := string(c.text)
    bang := false