Simple example fails with unexpected token "<EOF>"

[Dogacel]

Here is the simple example I am trying to use:

// nolint: govet, golint
package main

import (
	"github.com/alecthomas/participle/v2"
	"github.com/alecthomas/participle/v2/lexer"
	"github.com/alecthomas/repr"
)

type Text struct {
	Pos lexer.Position

	First string `  @ident `
}

var (
	testParser = participle.MustBuild[Text](
		participle.Lexer(
			lexer.MustSimple(
				[]lexer.SimpleRule{
					// Letters and Digits
					{"letter", `[a-zA-Z]`},
					{"decimalDigit", `[0-9]`},

					// Identifiers
					{"ident", `letter ( letter | decimalDigit )*`},
				}),
		),
	)
)

func main() {
	proto, err := testParser.ParseString("string_test", `something`)

	if err != nil {
		panic(err)
	}

	repr.Println(proto, repr.Hide(&lexer.Position{}))
}

And it is giving me the error:

panic: string_test:1:10: unexpected token "<EOF>"

I have tried adding the token for <EOF> but couldn't manage to do it. Also I couldn't find any documentation regarding this.

I am using MacOS w/ go 1.19.3

[alecthomas]

Your lexer is not correct. Each entry is a self-contained regex pattern.

[alecthomas]

Try looking through the _examples folder.

[Dogacel]

Your lexer is not correct. Each entry is a self-contained regex pattern.

Got it, I am hoping this issue will guide other who also see the same issue.

My observation is: If lever fails to parse any rule it seems like this EOF error is thrown.