refactor: modernize stdlib usage and move matchers into dsl

- Move Matcher types and matching logic from runner/matcher.go into
  the dsl package as methods on the Matcher types. Runner now calls
  t.Stdout.Match(label, actual) instead of type-switching via a
  package-level applyMatcher helper.
- Replace custom contains/containsString helpers with slices.Contains
  in dsl/build.go and runner/compiler.go.
- Use maps.Copy instead of manual map copy in BuildConfig.MergeFrom.
- Adopt strings.SplitSeq, strings.CutPrefix and the `for range N` loop
  form in runner/limiter_linux.go.
- Ignore example/imdb build artifact.

.gitignore

@@ -1,2 +1,5 @@
 example/c-sum/solution
 example/solution/solution
+.DS_Store
+*/.DS_Store
+.claude

dsl/ast.go

@@ -1,6 +1,8 @@
 package dsl
 
-import "time"
+import (
+	"time"
+)
 
 type File struct {
 	Build        string
@@ -74,42 +76,3 @@ type Test struct {
 	Stderr   Matcher
 	OutFiles map[string]string
 }
-
-type Matcher interface {
-	matcherNode()
-}
-
-type ExactMatcher struct {
-	Value string
-}
-
-func (ExactMatcher) matcherNode() {}
-
-type ContainsMatcher struct {
-	Substr string
-}
-
-func (ContainsMatcher) matcherNode() {}
-
-type RegexMatcher struct {
-	Pattern string
-}
-
-func (RegexMatcher) matcherNode() {}
-
-type NumericEpsMatcher struct {
-	Epsilon float64
-	Value   string
-}
-
-func (NumericEpsMatcher) matcherNode() {}
-
-type AnyOrderMatcher struct {
-	Lines []string
-}
-
-func (AnyOrderMatcher) matcherNode() {}
-
-type NoMatcher struct{}
-
-func (NoMatcher) matcherNode() {}

dsl/build.go

@@ -1,5 +1,10 @@
 package dsl
 
+import (
+	"maps"
+	"slices"
+)
+
 type BuildProfile int
 
 const (
@@ -105,9 +110,7 @@ func (dst *BuildConfig) MergeFrom(src *BuildConfig) {
 		if dst.Defines == nil {
 			dst.Defines = map[string]string{}
 		}
-		for k, v := range src.Defines {
-			dst.Defines[k] = v
-		}
+		maps.Copy(dst.Defines, src.Defines)
 	}
 }
 
@@ -132,24 +135,15 @@ func (b *BuildConfig) Resolve(defaults *BuildConfig, os string) BuildConfig {
 }
 
 func (b *BuildConfig) AppliesTo(os, compiler string) bool {
-	if len(b.Platforms) > 0 && !contains(b.Platforms, os) {
+	if len(b.Platforms) > 0 && !slices.Contains(b.Platforms, os) {
 		return false
 	}
-	if len(b.Compilers) > 0 && !contains(b.Compilers, compiler) {
+	if len(b.Compilers) > 0 && !slices.Contains(b.Compilers, compiler) {
 		return false
 	}
 	return true
 }
 
-func contains(xs []string, x string) bool {
-	for _, v := range xs {
-		if v == x {
-			return true
-		}
-	}
-	return false
-}
-
 type ToolchainSpec struct {
 	Name      string
 	Platforms []string

dsl/lexer.go

@@ -371,8 +371,6 @@ func (l *Lexer) readNumberOrDuration(line, col int) (Token, error) {
 	return Token{TOKEN_INT, buf.String(), line, col}, nil
 }
 
-// tryReadSizeSuffix reads memory size suffixes: B, K, KB, KiB, M, MB, MiB, G, GB, GiB.
-// Units are case-sensitive uppercase to avoid collision with duration "m" (minutes).
 func (l *Lexer) tryReadSizeSuffix() string {
 	ch, ok := l.peek()
 	if !ok {

dsl/matcher.go

@@ -1,4 +1,4 @@
-package runner
+package dsl
 
 import (
 	"fmt"
@@ -7,15 +7,23 @@ import (
 	"sort"
 	"strconv"
 	"strings"
-
-	"github.com/Mond1c/judge/dsl"
 )
 
-func applyMatcher(label string, m dsl.Matcher, actual string) []string {
-	switch m := m.(type) {
-	case dsl.NoMatcher:
-		return nil
-	case dsl.ExactMatcher:
+// TODO: maybe move to ast.go
+type Matcher interface {
+	matcherNode()
+
+	Match(label, actual string) []string
+}
+
+type ExactMatcher struct {
+	Value string
+}
+
+func (ExactMatcher) matcherNode() {}
+
+// TODO: think about pointer receivers
+func (m ExactMatcher) Match(label, actual string) []string {
 	if actual != m.Value {
 		return []string{fmt.Sprintf(
 			"%s mismatch:\n  expected: %q\n  actual:   %q",
@@ -23,7 +31,15 @@ func applyMatcher(label string, m dsl.Matcher, actual string) []string {
 		)}
 	}
 	return nil
-	case dsl.ContainsMatcher:
+}
+
+type ContainsMatcher struct {
+	Substr string
+}
+
+func (ContainsMatcher) matcherNode() {}
+
+func (m ContainsMatcher) Match(label, actual string) []string {
 	if !strings.Contains(actual, m.Substr) {
 		return []string{fmt.Sprintf(
 			"%s: expected to contain %q, got %q",
@@ -31,11 +47,20 @@ func applyMatcher(label string, m dsl.Matcher, actual string) []string {
 		)}
 	}
 	return nil
-	case dsl.RegexMatcher:
+}
+
+type RegexMatcher struct {
+	Pattern string
+}
+
+func (RegexMatcher) matcherNode() {}
+
+func (m RegexMatcher) Match(label, actual string) []string {
 	re, err := regexp.Compile(m.Pattern)
 	if err != nil {
 		return []string{fmt.Sprintf("%s: invalid regex %q: %v", label, m.Pattern, err)}
 	}
+
 	if !re.MatchString(actual) {
 		return []string{fmt.Sprintf(
 			"%s: %q does not match regex %q",
@@ -43,21 +68,29 @@ func applyMatcher(label string, m dsl.Matcher, actual string) []string {
 		)}
 	}
 	return nil
-
-	case dsl.NumericEpsMatcher:
-		errs := matchNumericEps(label, m, actual)
-		return errs
-
-	case dsl.AnyOrderMatcher:
-		return matchAnyOrder(label, m, actual)
-
-	default:
-		return []string{fmt.Sprintf("unknown matcher type %T", m)}
-
-	}
 }
 
-func matchNumericEps(label string, m dsl.NumericEpsMatcher, actual string) []string {
+type NumericEpsMatcher struct {
+	Epsilon float64
+	Value   string
+}
+
+func (NumericEpsMatcher) matcherNode() {}
+
+func parseNumbers(s string) ([]float64, error) {
+	fields := strings.Fields(s)
+	nums := make([]float64, 0, len(fields))
+	for _, f := range fields {
+		n, err := strconv.ParseFloat(f, 64)
+		if err != nil {
+			return nil, fmt.Errorf("not a number: %q", f)
+		}
+		nums = append(nums, n)
+	}
+	return nums, nil
+}
+
+func (m NumericEpsMatcher) Match(label, actual string) []string {
 	expectedNums, err := parseNumbers(m.Value)
 	if err != nil {
 		return []string{fmt.Sprintf("%s: cannot parse expected numbers %q: %v", label, m.Value, err)}
@@ -85,20 +118,21 @@ func matchNumericEps(label string, m dsl.NumericEpsMatcher, actual string) []str
 	return errs
 }
 
-func parseNumbers(s string) ([]float64, error) {
-	fields := strings.Fields(s)
-	nums := make([]float64, 0, len(fields))
-	for _, f := range fields {
-		n, err := strconv.ParseFloat(f, 64)
-		if err != nil {
-			return nil, fmt.Errorf("not a number: %q", f)
-		}
-		nums = append(nums, n)
-	}
-	return nums, nil
+type AnyOrderMatcher struct {
+	Lines []string
 }
 
-func matchAnyOrder(label string, m dsl.AnyOrderMatcher, actual string) []string {
+func (AnyOrderMatcher) matcherNode() {}
+
+func splitLines(s string) []string {
+	s = strings.TrimRight(s, "\n")
+	if s == "" {
+		return []string{}
+	}
+	return strings.Split(s, "\n")
+}
+
+func (m AnyOrderMatcher) Match(label, actual string) []string {
 	actualLines := splitLines(actual)
 	expectedLines := make([]string, len(m.Lines))
 	copy(expectedLines, m.Lines)
@@ -125,10 +159,10 @@ func matchAnyOrder(label string, m dsl.AnyOrderMatcher, actual string) []string
 	return errs
 }
 
-func splitLines(s string) []string {
-	s = strings.TrimRight(s, "\n")
-	if s == "" {
-		return []string{}
-	}
-	return strings.Split(s, "\n")
+type NoMatcher struct{}
+
+func (NoMatcher) matcherNode() {}
+
+func (NoMatcher) Match(label, actual string) []string {
+	return nil
 }

runner/compiler.go

@@ -3,6 +3,7 @@ package runner
 import (
 	"fmt"
 	"runtime"
+	"slices"
 	"sort"
 	"strings"
 
@@ -161,7 +162,7 @@ func compileMSVC(cfg dsl.BuildConfig, tc Toolchain, outputPath string) []string
 		argv = append(argv, "/W4", "/permissive-")
 	}
 
-	if containsString(cfg.Sanitize, "address") && cfg.Profile != dsl.ProfileSanitized {
+	if slices.Contains(cfg.Sanitize, "address") && cfg.Profile != dsl.ProfileSanitized {
 		argv = append(argv, "/fsanitize=address")
 	}
 
@@ -195,12 +196,3 @@ func sortedKeys(m map[string]string) []string {
 	sort.Strings(keys)
 	return keys
 }
-
-func containsString(xs []string, x string) bool {
-	for _, v := range xs {
-		if v == x {
-			return true
-		}
-	}
-	return false
-}

runner/limiter_linux.go

@@ -102,9 +102,9 @@ func createScopeCgroup() (string, error) {
 		return "", fmt.Errorf("read /proc/self/cgroup: %w", err)
 	}
 	var rel string
-	for _, line := range strings.Split(strings.TrimSpace(string(data)), "\n") {
-		if strings.HasPrefix(line, "0::") {
-			rel = strings.TrimPrefix(line, "0::")
+	for line := range strings.SplitSeq(strings.TrimSpace(string(data)), "\n") {
+		if after, ok := strings.CutPrefix(line, "0::"); ok {
+			rel = after
 			break
 		}
 	}
@@ -200,7 +200,7 @@ func (l *linuxLimiter) collect() limitStats {
 		}
 	}
 	if data, err := os.ReadFile(filepath.Join(l.cgPath, "memory.events")); err == nil {
-		for _, line := range strings.Split(string(data), "\n") {
+		for line := range strings.SplitSeq(string(data), "\n") {
 			fields := strings.Fields(line)
 			if len(fields) != 2 {
 				continue
@@ -217,7 +217,7 @@ func (l *linuxLimiter) cleanup() {
 	if l.cgPath == "" {
 		return
 	}
-	for i := 0; i < 10; i++ {
+	for range 10 {
 		err := os.Remove(l.cgPath)
 		if err == nil || os.IsNotExist(err) {
 			l.cgPath = ""

runner/runner.go

@@ -558,10 +558,10 @@ func (r *Runner) runTest(t *dsl.Test) *TestResult {
 		tr.addFailure("exit code: expected %d, got %d", *t.ExitCode, actualCode)
 	}
 
-	for _, f := range applyMatcher("stdout", t.Stdout, tr.ActualStdout) {
+	for _, f := range t.Stdout.Match("stdout", tr.ActualStdout) {
 		tr.addFailure("%s", f)
 	}
-	for _, f := range applyMatcher("stderr", t.Stderr, tr.ActualStderr) {
+	for _, f := range t.Stderr.Match("stderr", tr.ActualStderr) {
 		tr.addFailure("%s", f)
 	}