feat: Linting Regex (#43)

* add regex examples

* detect repeated regex compilation

* fix: Improve slice bounds check lint for range loop contexts (#45)

* fix: Improve slice bounds check lint for range loop contexts

* update docs

go.mod

@@ -14,6 +14,8 @@ require (
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/stretchr/objx v0.5.2 // indirect
 	go.uber.org/multierr v1.10.0 // indirect
+	golang.org/x/mod v0.19.0 // indirect
+	golang.org/x/sync v0.7.0 // indirect
 	golang.org/x/sys v0.22.0 // indirect
 )
 

go.sum

@@ -15,10 +15,16 @@ github.com/stretchr/objx v0.5.2 h1:xuMeJ0Sdp5ZMRXx/aWO6RZxdr3beISkG5/G/aIRr3pY=
 github.com/stretchr/objx v0.5.2/go.mod h1:FRsXN1f5AsAjCGJKqEizvkpNtU+EGNCLh3NxZ/8L+MA=
 github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
 github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
+go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
 go.uber.org/multierr v1.10.0 h1:S0h4aNzvfcFsC3dRF1jLoaov7oRaKqRGC/pUEJ2yvPQ=
 go.uber.org/multierr v1.10.0/go.mod h1:20+QtiLqy0Nd6FdQB9TLXag12DsQkrbs3htMFfDN80Y=
 go.uber.org/zap v1.27.0 h1:aJMhYGrd5QSmlpLMr2MftRKl7t8J8PTZPA732ud/XR8=
 go.uber.org/zap v1.27.0/go.mod h1:GB2qFLM7cTU87MWRP2mPIjqfIDnGu+VIO4V/SdhGo2E=
+golang.org/x/mod v0.19.0 h1:fEdghXQSo20giMthA7cd28ZC+jts4amQ3YMXiP5oMQ8=
+golang.org/x/mod v0.19.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
+golang.org/x/sync v0.7.0 h1:YsImfSBoP9QPYL0xyKJPq0gcaJdG3rInoqxTWbfQu9M=
+golang.org/x/sync v0.7.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.22.0 h1:RI27ohtqKCnwULzJLqkv897zojh5/DwS/ENaMzUOaWI=

internal/engine.go

@@ -42,6 +42,7 @@ func (e *Engine) registerDefaultRules() {
 		&EmitFormatRule{},
 		&DetectCycleRule{},
 		&GnoSpecificRule{},
+		&RepeatedRegexCompilationRule{},
 		&UselessBreakRule{},
 	)
 }

internal/lints/regex_lint_test.go

@@ -0,0 +1,95 @@
+package lints
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestDetectRepeatedRegexCompilation(t *testing.T) {
+	tests := []struct {
+		name     string
+		code     string
+		expected int
+	}{
+		{
+			name: "No repeated compilation",
+			code: `
+package main
+
+import "regexp"
+
+func noRepeat() {
+	r1 := regexp.MustCompile("pattern1")
+	r2 := regexp.MustCompile("pattern2")
+	_ = r1
+	_ = r2
+}
+`,
+			expected: 0,
+		},
+		{
+			name: "Repeated compilation",
+			code: `
+package main
+
+import "regexp"
+
+func withRepeat() {
+	r1 := regexp.MustCompile("pattern")
+	r2 := regexp.MustCompile("pattern")
+	_ = r1
+	_ = r2
+}
+`,
+			expected: 1,
+		},
+		{
+			name: "Multiple repeated compilations",
+			code: `
+package main
+
+import "regexp"
+
+func multipleRepeats() {
+	r1 := regexp.MustCompile("pattern1")
+	r2 := regexp.MustCompile("pattern1")
+	r3 := regexp.MustCompile("pattern2")
+	r4 := regexp.MustCompile("pattern2")
+	_ = r1
+	_ = r2
+	_ = r3
+	_ = r4
+}
+`,
+			expected: 2,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tempDir, err := os.MkdirTemp("", "regex-test")
+			require.NoError(t, err)
+			defer os.RemoveAll(tempDir)
+
+			tempFile := filepath.Join(tempDir, "test.go")
+			err = os.WriteFile(tempFile, []byte(tt.code), 0o644)
+			require.NoError(t, err)
+
+			issues, err := DetectRepeatedRegexCompilation(tempFile)
+			require.NoError(t, err)
+
+			assert.Len(t, issues, tt.expected)
+
+			if tt.expected > 0 {
+				for _, issue := range issues {
+					assert.Equal(t, "repeatedregexcompilation", issue.Rule)
+					assert.Contains(t, issue.Message, "regexp.Compile called with same pattern more than once")
+				}
+			}
+		})
+	}
+}

internal/lints/repeated_regex_compilation.go

@@ -0,0 +1,120 @@
+package lints
+
+import (
+	"go/ast"
+	"go/token"
+
+	tt "github.com/gnoswap-labs/lint/internal/types"
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/packages"
+)
+
+var RepeatedRegexCompilationAnalyzer = &analysis.Analyzer{
+	Name: "repeatedregexcompilation",
+	Doc:  "Checks for repeated compilation of the same regex pattern",
+	Run:  runRepeatedRegexCompilation,
+}
+
+func DetectRepeatedRegexCompilation(filename string) ([]tt.Issue, error) {
+	issues, err := runAnalyzer(filename, RepeatedRegexCompilationAnalyzer)
+	if err != nil {
+		return nil, err
+	}
+	return issues, nil
+}
+
+func runAnalyzer(filename string, a *analysis.Analyzer) ([]tt.Issue, error) {
+	cfg := &packages.Config{
+		Mode:  packages.NeedFiles | packages.NeedSyntax | packages.NeedTypesInfo | packages.NeedTypes,
+		Tests: false,
+	}
+
+	pkgs, err := packages.Load(cfg, filename)
+	if err != nil {
+		return nil, err
+	}
+
+	var diagnostics []analysis.Diagnostic
+	pass := &analysis.Pass{
+		Analyzer:  a,
+		Fset:      pkgs[0].Fset,
+		Files:     pkgs[0].Syntax,
+		Pkg:       pkgs[0].Types,
+		TypesInfo: pkgs[0].TypesInfo,
+		ResultOf:  make(map[*analysis.Analyzer]interface{}),
+		Report: func(d analysis.Diagnostic) {
+			diagnostics = append(diagnostics, d)
+		},
+	}
+
+	_, err = a.Run(pass)
+	if err != nil {
+		return nil, err
+	}
+
+	var issues []tt.Issue
+	for _, diag := range diagnostics {
+		issues = append(issues, tt.Issue{
+			Rule:     a.Name,
+			Filename: filename,
+			Start:    pass.Fset.Position(diag.Pos),
+			End:      pass.Fset.Position(diag.End),
+			Message:  diag.Message,
+		})
+	}
+
+	return issues, nil
+}
+
+func runRepeatedRegexCompilation(pass *analysis.Pass) (interface{}, error) {
+	for _, file := range pass.Files {
+		ast.Inspect(file, func(n ast.Node) bool {
+			funcDecl, ok := n.(*ast.FuncDecl)
+			if !ok {
+				return true
+			}
+
+			regexPatterns := make(map[string]token.Pos)
+			ast.Inspect(funcDecl.Body, func(node ast.Node) bool {
+				callExpr, ok := node.(*ast.CallExpr)
+				if !ok {
+					return true
+				}
+
+				if isRegexpCompile(callExpr) {
+					if pattern, ok := getRegexPattern(callExpr); ok {
+						if firstPos, exists := regexPatterns[pattern]; exists {
+							pass.Reportf(callExpr.Pos(), "regexp.Compile called with same pattern more than once. First occurrence at line %d", pass.Fset.Position(firstPos).Line)
+						} else {
+							regexPatterns[pattern] = callExpr.Pos()
+						}
+					}
+				}
+
+				return true
+			})
+
+			return true
+		})
+	}
+
+	return nil, nil
+}
+
+func isRegexpCompile(callExpr *ast.CallExpr) bool {
+	if selExpr, ok := callExpr.Fun.(*ast.SelectorExpr); ok {
+		if ident, ok := selExpr.X.(*ast.Ident); ok {
+			return ident.Name == "regexp" && (selExpr.Sel.Name == "Compile" || selExpr.Sel.Name == "MustCompile")
+		}
+	}
+	return false
+}
+
+func getRegexPattern(callExpr *ast.CallExpr) (string, bool) {
+	if len(callExpr.Args) > 0 {
+		if lit, ok := callExpr.Args[0].(*ast.BasicLit); ok && lit.Kind == token.STRING {
+			return lit.Value, true
+		}
+	}
+	return "", false
+}

internal/rule_set.go

@@ -111,6 +111,19 @@ func (r *UselessBreakRule) Name() string {
 	return "useless-break"
 }
 
+// -----------------------------------------------------------------------------
+// Regex related rules
+
+type RepeatedRegexCompilationRule struct{}
+
+func (r *RepeatedRegexCompilationRule) Check(filename string, node *ast.File, fset *token.FileSet) ([]tt.Issue, error) {
+	return lints.DetectRepeatedRegexCompilation(filename)
+}
+
+func (r *RepeatedRegexCompilationRule) Name() string {
+	return "repeated-regex-compilation"
+}
+
 // -----------------------------------------------------------------------------
 
 type CyclomaticComplexityRule struct {

testdata/regex/regex0.gno

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"regexp"
+
+	"gno.land/p/demo/ufmt"
+)
+
+func repeatedRegexCompilation(inputs []string) {
+    for _, input := range inputs {
+        regex := regexp.MustCompile(`\d+`)
+        matches := regex.FindAllString(input, -1)
+        ufmt.Println(matches)
+    }
+}

testdata/regex/regex1.gno

@@ -0,0 +1,16 @@
+package main
+
+import (
+	"regexp"
+
+	"gno.land/p/demo/ufmt"
+)
+
+
+func avoidRepeatedRegexCompilation(inputs []string) {
+    regex := regexp.MustCompile(`\d+`)
+    for _, input := range inputs {
+        matches := regex.FindAllString(input, -1)
+        ufmt.Println(matches)
+    }
+}

testdata/regex/regex2.gno

@@ -0,0 +1,9 @@
+package main
+
+import (
+	"regexp"
+)
+
+func complexRegexExample() {
+    regex := regexp.MustCompile(`^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$`)
+}

testdata/regex/regex3.gno

@@ -0,0 +1,10 @@
+package main
+
+import "regexp"
+
+func unnecessaryCaptureGroupExample() {
+    regex := regexp.MustCompile(`(https?://\S+)`)
+}
+
+// minimized:
+// (?:https?://\S+)`

testdata/regex/regex4.gno

@@ -0,0 +1,11 @@
+package main
+
+import "regexp"
+
+func greedyQuantifierExample(largeInput string) {
+    regex := regexp.MustCompile(`<.*>`)
+    matches := regex.FindAllString(largeInput, -1)
+}
+
+// minimized:
+// <.*?>

testdata/regex/regex5.gno

@@ -0,0 +1,17 @@
+package main
+
+import (
+	"regexp"
+)
+
+func preferStringMethodExample(input string) bool {
+    return regexp.MustCompile(`^[a-zA-Z]+$`).MatchString(input)
+}
+
+// Suggestion:
+// for _, char := range input {
+//     if !unicode.IsLetter(char) {
+//         return false
+//     }
+// }
+// return true

testdata/regex/regex6.gno

@@ -0,0 +1,10 @@
+package main
+
+import "regexp"
+
+func withRepeat() {
+	r1 := regexp.MustCompile("pattern")
+	r2 := regexp.MustCompile("pattern")
+	_ = r1
+	_ = r2
+}