feat: gasm-devkit 0.1.0 — GAsm lexer, parser, linter, formatter, LSP and amd64 assembler

Assisted-by: Qwen 3.8 Max Preview
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2026-07-06 09:49:50 +02:00
commit d5a4a6de45
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// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: BSD-3-Clause
// Command gasm is the developer frontend for GAsm — Go's Plan 9 assembler.
// It bundles a token dumper, a parser, a formatter, a linter and a language
// server into one binary. Every subcommand works headlessly so it can be
// driven from scripts and CI as well as from an editor.
package main
import (
"flag"
"fmt"
"io"
"os"
"strings"
"sourcedock.dev/petrbalvin/gasm-devkit/arch"
"sourcedock.dev/petrbalvin/gasm-devkit/asm"
"sourcedock.dev/petrbalvin/gasm-devkit/ast"
"sourcedock.dev/petrbalvin/gasm-devkit/format"
"sourcedock.dev/petrbalvin/gasm-devkit/lexer"
"sourcedock.dev/petrbalvin/gasm-devkit/lint"
"sourcedock.dev/petrbalvin/gasm-devkit/lsp"
"sourcedock.dev/petrbalvin/gasm-devkit/parser"
)
// version is the release version, stamped at build time via
// -ldflags "-X main.version=…" (defaulting to the current release).
var version = "0.1.0"
func main() {
if len(os.Args) < 2 {
usage(os.Stderr)
os.Exit(2)
}
switch os.Args[1] {
case "tokens":
os.Exit(cmdTokens(os.Args[2:]))
case "parse":
os.Exit(cmdParse(os.Args[2:]))
case "fmt":
os.Exit(cmdFmt(os.Args[2:]))
case "lint":
os.Exit(cmdLint(os.Args[2:]))
case "asm":
os.Exit(cmdAsm(os.Args[2:]))
case "lsp":
os.Exit(cmdLSP(os.Args[2:]))
case "version", "--version", "-V":
fmt.Printf("gasm %s\n", version)
case "help", "-h", "--help":
usage(os.Stdout)
default:
fmt.Fprintf(os.Stderr, "gasm: unknown command %q\n\n", os.Args[1])
usage(os.Stderr)
os.Exit(2)
}
}
func usage(w io.Writer) {
fmt.Fprintf(w, `gasm %s — developer tooling for Go's Plan 9 assembler
Usage:
gasm tokens <file> print the lexical token stream
gasm parse <file> parse and report syntax errors
gasm fmt [-w] <file...> canonicalise formatting (-w writes in place)
gasm lint <file...> run static checks
gasm asm [-o out.bin] <file> assemble to machine code (amd64, Phase 2)
gasm lsp run the language server over stdio
gasm version print the version
`, version)
}
// readSource returns the contents of path, or stdin when path is "-".
func readSource(path string) (string, error) {
if path == "-" {
b, err := io.ReadAll(os.Stdin)
return string(b), err
}
b, err := os.ReadFile(path)
return string(b), err
}
func cmdTokens(args []string) int {
fs := flag.NewFlagSet("tokens", flag.ExitOnError)
fs.Parse(args)
if fs.NArg() != 1 {
fmt.Fprintln(os.Stderr, "usage: gasm tokens <file>")
return 2
}
src, err := readSource(fs.Arg(0))
if err != nil {
fmt.Fprintln(os.Stderr, "gasm:", err)
return 1
}
for _, tok := range lexer.Tokenize(src) {
fmt.Printf("%s\t%s\t%q\n", tok.Pos, tok.Kind, tok.Text)
}
return 0
}
func cmdParse(args []string) int {
fs := flag.NewFlagSet("parse", flag.ExitOnError)
fs.Parse(args)
if fs.NArg() != 1 {
fmt.Fprintln(os.Stderr, "usage: gasm parse <file>")
return 2
}
path := fs.Arg(0)
src, err := readSource(path)
if err != nil {
fmt.Fprintln(os.Stderr, "gasm:", err)
return 1
}
file, errs := parser.Parse(path, src)
for _, e := range errs {
fmt.Fprintf(os.Stderr, "%s: %v\n", path, e)
}
if len(errs) > 0 {
return 1
}
funcs := 0
for _, d := range file.Decls {
if _, ok := d.(*ast.Text); ok {
funcs++
}
}
fmt.Printf("%s: OK — %d declarations, %d functions\n", path, len(file.Decls), funcs)
return 0
}
func cmdFmt(args []string) int {
fs := flag.NewFlagSet("fmt", flag.ExitOnError)
write := fs.Bool("w", false, "write result to the source file")
fs.Parse(args)
if fs.NArg() == 0 {
fmt.Fprintln(os.Stderr, "usage: gasm fmt [-w] <file...>")
return 2
}
rc := 0
for _, path := range fs.Args() {
src, err := readSource(path)
if err != nil {
fmt.Fprintln(os.Stderr, "gasm:", err)
rc = 1
continue
}
out := format.Source(path, src)
if *write {
if out != src {
if err := os.WriteFile(path, []byte(out), 0o644); err != nil {
fmt.Fprintln(os.Stderr, "gasm:", err)
rc = 1
}
}
continue
}
fmt.Print(out)
}
return rc
}
func cmdLint(args []string) int {
fs := flag.NewFlagSet("lint", flag.ExitOnError)
disable := fs.String("disable", "", "comma-separated rule codes to disable")
fs.Parse(args)
if fs.NArg() == 0 {
fmt.Fprintln(os.Stderr, "usage: gasm lint <file...>")
return 2
}
disabled := map[string]bool{}
for _, code := range strings.Split(*disable, ",") {
if code = strings.TrimSpace(code); code != "" {
disabled[code] = true
}
}
hadError := false
for _, path := range fs.Args() {
src, err := readSource(path)
if err != nil {
fmt.Fprintln(os.Stderr, "gasm:", err)
hadError = true
continue
}
file, errs := parser.Parse(path, src)
for _, e := range errs {
fmt.Fprintf(os.Stderr, "%s: %v\n", path, e)
hadError = true
}
diags := lint.File(file, lint.Config{Arch: arch.FromFilename(path), Disable: disabled})
for _, d := range diags {
fmt.Printf("%s:%d:%d: %s: %s [%s]\n", path, d.Pos.Line, d.Pos.Column, d.Severity, d.Message, d.Code)
if d.Severity == lint.Error {
hadError = true
}
}
}
if hadError {
return 1
}
return 0
}
func cmdLSP(args []string) int {
fs := flag.NewFlagSet("lsp", flag.ExitOnError)
fs.Parse(args)
srv := lsp.New(os.Stdin, os.Stdout)
if err := srv.Run(); err != nil {
fmt.Fprintln(os.Stderr, "gasm lsp:", err)
return 1
}
return 0
}
func cmdAsm(args []string) int {
fs := flag.NewFlagSet("asm", flag.ExitOnError)
out := fs.String("o", "", "write the concatenated machine code to this file")
fs.Parse(args)
if fs.NArg() != 1 {
fmt.Fprintln(os.Stderr, "usage: gasm asm [-o out.bin] <file>")
return 2
}
path := fs.Arg(0)
if arch.FromFilename(path) != arch.AMD64 {
fmt.Fprintln(os.Stderr, "gasm asm: only amd64 is supported in this Phase 2 increment")
return 1
}
src, err := readSource(path)
if err != nil {
fmt.Fprintln(os.Stderr, "gasm:", err)
return 1
}
f, errs := parser.Parse(path, src)
for _, e := range errs {
fmt.Fprintf(os.Stderr, "%s: %v\n", path, e)
}
if len(errs) > 0 {
return 1
}
var all []byte
functions := 0
for _, d := range f.Decls {
txt, ok := d.(*ast.Text)
if !ok {
continue
}
code, _, err := asm.Assemble(txt)
if err != nil {
fmt.Fprintf(os.Stderr, "%s: %s: %v\n", path, txt.Name.Name, err)
return 1
}
functions++
fmt.Printf("%s: %d bytes\n", txt.Name.Name, len(code))
for i := 0; i < len(code); i += 16 {
end := i + 16
if end > len(code) {
end = len(code)
}
fmt.Printf(" %04x:", i)
for _, b := range code[i:end] {
fmt.Printf(" %02x", b)
}
fmt.Println()
}
all = append(all, code...)
}
if functions == 0 {
fmt.Fprintln(os.Stderr, "gasm asm: no assemblable TEXT functions found")
return 1
}
if *out != "" {
if err := os.WriteFile(*out, all, 0o644); err != nil {
fmt.Fprintln(os.Stderr, "gasm asm:", err)
return 1
}
fmt.Printf("wrote %d bytes to %s\n", len(all), *out)
}
return 0
}
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// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: BSD-3-Clause
package main
import (
"bytes"
"io"
"os"
"path/filepath"
"strings"
"testing"
)
const clean = "#include \"textflag.h\"\n" +
"TEXT ·f(SB), NOSPLIT, $0\n" +
"\tMOVQ AX, BX\n" +
"loop:\n" +
"\tJMP loop\n" +
"\tRET\n"
const buggy = "#include \"textflag.h\"\n" +
"TEXT ·f(SB), NOSPLIT, $0\n" +
"\tBOGUS AX, BX\n" +
"\tJMP nowhere\n" +
"\tRET\n"
func writeTemp(t *testing.T, name, content string) string {
t.Helper()
path := filepath.Join(t.TempDir(), name)
if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
t.Fatal(err)
}
return path
}
// capture runs fn with stdout and stderr redirected and returns both plus the
// exit code fn produced.
func capture(fn func() int) (stdout, stderr string, code int) {
oldOut, oldErr := os.Stdout, os.Stderr
rOut, wOut, _ := os.Pipe()
rErr, wErr, _ := os.Pipe()
os.Stdout, os.Stderr = wOut, wErr
code = fn()
wOut.Close()
wErr.Close()
os.Stdout, os.Stderr = oldOut, oldErr
ob, _ := io.ReadAll(rOut)
eb, _ := io.ReadAll(rErr)
return string(ob), string(eb), code
}
func TestCmdTokens(t *testing.T) {
path := writeTemp(t, "f_amd64.s", clean)
out, _, code := capture(func() int { return cmdTokens([]string{path}) })
if code != 0 {
t.Fatalf("code = %d", code)
}
if !strings.Contains(out, "IDENT") || !strings.Contains(out, "TEXT") {
t.Errorf("token dump missing expected tokens:\n%s", out)
}
}
func TestCmdParseOK(t *testing.T) {
path := writeTemp(t, "f_amd64.s", clean)
out, _, code := capture(func() int { return cmdParse([]string{path}) })
if code != 0 {
t.Fatalf("code = %d", code)
}
if !strings.Contains(out, "OK") || !strings.Contains(out, "1 functions") {
t.Errorf("parse output = %q", out)
}
}
func TestCmdParseError(t *testing.T) {
path := writeTemp(t, "bad_amd64.s", "TEXT ·f(SB), NOSPLIT, $0\n) (\n\tRET\n")
_, errOut, code := capture(func() int { return cmdParse([]string{path}) })
if code != 1 {
t.Fatalf("code = %d, want 1", code)
}
if errOut == "" {
t.Error("expected a parse error on stderr")
}
}
func TestCmdParseMissingFile(t *testing.T) {
_, _, code := capture(func() int { return cmdParse([]string{"/nonexistent/file.s"}) })
if code != 1 {
t.Fatalf("code = %d, want 1", code)
}
}
func TestCmdLintClean(t *testing.T) {
path := writeTemp(t, "f_amd64.s", clean)
_, _, code := capture(func() int { return cmdLint([]string{path}) })
if code != 0 {
t.Fatalf("clean file should lint with code 0, got %d", code)
}
}
func TestCmdLintErrors(t *testing.T) {
path := writeTemp(t, "f_amd64.s", buggy)
out, _, code := capture(func() int { return cmdLint([]string{path}) })
if code != 1 {
t.Fatalf("code = %d, want 1", code)
}
if !strings.Contains(out, "unknown-instruction") || !strings.Contains(out, "undefined-label") {
t.Errorf("lint output missing expected codes:\n%s", out)
}
}
func TestCmdLintDisable(t *testing.T) {
path := writeTemp(t, "f_amd64.s", buggy)
args := []string{"-disable", "unknown-instruction,undefined-label", path}
_, _, code := capture(func() int { return cmdLint(args) })
if code != 0 {
t.Fatalf("disabling both rules should yield code 0, got %d", code)
}
}
func TestCmdFmtStdout(t *testing.T) {
path := writeTemp(t, "f_amd64.s", "TEXT ·f(SB),NOSPLIT,$0\nMOVQ AX,BX\nRET\n")
out, _, code := capture(func() int { return cmdFmt([]string{path}) })
if code != 0 {
t.Fatalf("code = %d", code)
}
if !strings.Contains(out, "TEXT ·f(SB), NOSPLIT, $0") || !strings.Contains(out, "\tMOVQ AX, BX") {
t.Errorf("formatted output unexpected:\n%s", out)
}
}
func TestCmdFmtWrite(t *testing.T) {
path := writeTemp(t, "f_amd64.s", "TEXT ·f(SB),NOSPLIT,$0\nMOVQ AX,BX\nRET\n")
_, _, code := capture(func() int { return cmdFmt([]string{"-w", path}) })
if code != 0 {
t.Fatalf("code = %d", code)
}
b, _ := os.ReadFile(path)
if !strings.Contains(string(b), "\tMOVQ AX, BX") {
t.Errorf("file not rewritten:\n%s", b)
}
// Idempotent: a second -w pass leaves the file unchanged.
_, _, _ = capture(func() int { return cmdFmt([]string{"-w", path}) })
b2, _ := os.ReadFile(path)
if string(b) != string(b2) {
t.Error("fmt -w is not idempotent")
}
}
func TestUsage(t *testing.T) {
var b bytes.Buffer
usage(&b)
if !strings.Contains(b.String(), "gasm") {
t.Errorf("usage text unexpected:\n%s", b.String())
}
}
func TestCmdArgErrors(t *testing.T) {
// Missing file arguments produce a usage error (code 2).
if _, _, code := capture(func() int { return cmdFmt(nil) }); code != 2 {
t.Errorf("cmdFmt() code = %d, want 2", code)
}
if _, _, code := capture(func() int { return cmdLint(nil) }); code != 2 {
t.Errorf("cmdLint() code = %d, want 2", code)
}
if _, _, code := capture(func() int { return cmdTokens(nil) }); code != 2 {
t.Errorf("cmdTokens() code = %d, want 2", code)
}
if _, _, code := capture(func() int { return cmdParse(nil) }); code != 2 {
t.Errorf("cmdParse() code = %d, want 2", code)
}
}