modernc.org/token v1.1.0: NewFile, File, File.AddLine

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify pkg:golang/modernc.org/token@v1.1.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/modernc.org/token@v1.1.0

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:c54c518fcbca1caa383da4e18000b9f65541ec1aa028256c6a082cf7d5ab4a58","contract":["token.NewFile creates a File with the specified name and size","File.AddLine records line starts and increments LineCount","File.Position maps byte offsets to 1-based line and column positions","File.SetLinesForContent computes line offsets from content bytes"],"goal":"verify pkg:golang/modernc.org/token@v1.1.0","kind":"HOW","packages":["pkg:golang/modernc.org/token@v1.1.0"],"schemaVersion":1,"symbols":["modernc.org/token.NewFile","modernc.org/token.File","modernc.org/token.File.AddLine","modernc.org/token.File.LineCount","modernc.org/token.File.Position","modernc.org/token.File.SetLinesForContent"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/modernc.org/token@v1.1.0"],"schemaVersion":1,"subject":"pkg:golang/modernc.org/token@v1.1.0","symbols":["modernc.org/token.NewFile","modernc.org/token.File","modernc.org/token.File.AddLine","modernc.org/token.File.LineCount","modernc.org/token.File.Position","modernc.org/token.File.SetLinesForContent"],"verifierAdapter":"golang@1"}

module sample

go 1.22

require modernc.org/token v1.1.0

modernc.org/token v1.1.0 h1:Xl7Ap9dKaEs5kLoOQeQmPWevfnk/DM5qcLcYlA8ys6Y=
modernc.org/token v1.1.0/go.mod h1:UGzOrNV1mAFSEB63lOFHIpNRUVMvYTc6yu1SMY/XTDM=

package sample

import (
	"modernc.org/token"
)

// SourceFile wraps token.File to manage file positions and line numbers.
type SourceFile struct {
	File *token.File
}

// NewSourceFile creates a new SourceFile with the given filename and size.
func NewSourceFile(filename string, size int) *SourceFile {
	return &SourceFile{
		File: token.NewFile(filename, size),
	}
}

// AddLine records a new line start offset.
func (sf *SourceFile) AddLine(offset int) {
	sf.File.AddLine(offset)
}

// LineCount returns the total number of lines in the file.
func (sf *SourceFile) LineCount() int {
	return sf.File.LineCount()
}

// Position resolves a byte offset to a token.Position.
func (sf *SourceFile) Position(offset int) token.Position {
	pos := sf.File.Pos(offset)
	return sf.File.Position(pos)
}

// SetLinesForContent sets the line offsets for given file content.
func (sf *SourceFile) SetLinesForContent(content []byte) {
	sf.File.SetLinesForContent(content)
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/modernc.org/token@v1.1.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/modernc.org/token@v1.1.0"
  ]
}

package main

import (
	"fmt"
	"os"

	"sample"
)

func main() {
	// Assertion 1: token.NewFile creates a File with the specified name and size
	filename := "test.txt"
	fileSize := 100
	sf := sample.NewSourceFile(filename, fileSize)
	if sf.File.Name() != filename {
		fmt.Fprintf(os.Stderr, "expected name %s, got %s\n", filename, sf.File.Name())
		os.Exit(1)
	}
	if sf.File.Size() != fileSize {
		fmt.Fprintf(os.Stderr, "expected size %d, got %d\n", fileSize, sf.File.Size())
		os.Exit(1)
	}

	// Assertion 2: File.AddLine records line starts and increments LineCount
	if initialLines := sf.LineCount(); initialLines != 1 {
		fmt.Fprintf(os.Stderr, "expected initial line count 1, got %d\n", initialLines)
		os.Exit(1)
	}
	sf.AddLine(20)
	sf.AddLine(50)
	if lines := sf.LineCount(); lines != 3 {
		fmt.Fprintf(os.Stderr, "expected line count 3, got %d\n", lines)
		os.Exit(1)
	}

	// Assertion 3: File.Position maps byte offsets to 1-based line and column positions
	pos := sf.Position(25)
	if !pos.IsValid() {
		fmt.Fprintf(os.Stderr, "expected valid position at offset 25\n")
		os.Exit(1)
	}
	if pos.Filename != filename {
		fmt.Fprintf(os.Stderr, "expected filename %s, got %s\n", filename, pos.Filename)
		os.Exit(1)
	}
	if pos.Line != 2 {
		fmt.Fprintf(os.Stderr, "expected line 2, got %d\n", pos.Line)
		os.Exit(1)
	}
	if pos.Column != 6 {
		fmt.Fprintf(os.Stderr, "expected column 6, got %d\n", pos.Column)
		os.Exit(1)
	}
	expectedStr := fmt.Sprintf("%s:2:6", filename)
	if pos.String() != expectedStr {
		fmt.Fprintf(os.Stderr, "expected string %s, got %s\n", expectedStr, pos.String())
		os.Exit(1)
	}

	// Assertion 4: File.SetLinesForContent computes line offsets from content bytes
	content := []byte("hello\nworld\ngolang\n")
	contentFile := sample.NewSourceFile("content.txt", len(content))
	contentFile.SetLinesForContent(content)
	if count := contentFile.LineCount(); count != 3 {
		fmt.Fprintf(os.Stderr, "expected line count 3 for content, got %d\n", count)
		os.Exit(1)
	}
	posWorld := contentFile.Position(7)
	if posWorld.Line != 2 || posWorld.Column != 2 {
		fmt.Fprintf(os.Stderr, "expected line 2 column 2, got line %d column %d\n", posWorld.Line, posWorld.Column)
		os.Exit(1)
	}

	fmt.Println("All modernc.org/token contract assertions passed.")
}