feat: regexp engine configuration

Add support for ECMAScript compatible regular expression engine via
regexp2 using functional options e.g.

vm := New(RegExp(regexp2.Creator{}))

This also adds function option support for the existing options:
* Debugger - Deprecates: SetDebuggerHandler
* RandomSource - Deprecates: SetRandomSource.
* Stack - Deprecates: SetStackLimit.
* StackTrace - Deprecates: SetStackTraceLimit.

Author: stevenh

builtin_string.go

@@ -2,11 +2,13 @@ package otto
 
 import (
 	"bytes"
-	"regexp"
+	restd "regexp"
 	"strconv"
 	"strings"
 	"unicode/utf16"
 	"unicode/utf8"
+
+	"github.com/robertkrimen/otto/regexp"
 )
 
 // String
@@ -170,7 +172,7 @@ func builtinStringMatch(call FunctionCall) Value {
 	return objectValue(call.runtime.newArrayOf(valueArray))
 }
 
-var builtinStringReplaceRegexp = regexp.MustCompile("\\$(?:[\\$\\&\\'\\`1-9]|0[1-9]|[1-9][0-9])")
+var builtinStringReplaceRegexp = restd.MustCompile("\\$(?:[\\$\\&\\'\\`1-9]|0[1-9]|[1-9][0-9])")
 
 func builtinStringFindAndReplaceString(input []byte, lastIndex int, match []int, target []byte, replaceValue []byte) []byte {
 	matchCount := len(match) / 2
@@ -215,7 +217,7 @@ func builtinStringReplace(call FunctionCall) Value {
 	searchObject := searchValue.object()
 
 	// TODO If a capture is -1?
-	var search *regexp.Regexp
+	var search regexp.Finder
 	global := false
 	find := 1
 	if searchValue.IsObject() && searchObject.class == classRegExpName {
@@ -226,7 +228,7 @@ func builtinStringReplace(call FunctionCall) Value {
 			global = true
 		}
 	} else {
-		search = regexp.MustCompile(regexp.QuoteMeta(searchValue.string()))
+		search = call.runtime.regExp.MustCompile(restd.QuoteMeta(searchValue.string()))
 	}
 
 	found := search.FindAllSubmatchIndex(target, find)

clone.go

@@ -17,6 +17,7 @@ func (rt *runtime) clone() *runtime {
 	defer rt.lck.Unlock()
 
 	out := &runtime{
+		regExp:     rt.regExp,
 		debugger:   rt.debugger,
 		random:     rt.random,
 		stackLimit: rt.stackLimit,

go.mod

@@ -3,6 +3,7 @@ module github.com/robertkrimen/otto
 go 1.18
 
 require (
+	github.com/dlclark/regexp2 v1.7.0
 	github.com/stretchr/testify v1.8.1
 	golang.org/x/text v0.4.0
 	gopkg.in/readline.v1 v1.0.0-20160726135117-62c6fe619375

go.sum

@@ -5,6 +5,8 @@ github.com/chzyer/test v1.0.0/go.mod h1:2JlltgoNkt4TW/z9V/IzDdFaMTM2JPIi26O1pF38
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/dlclark/regexp2 v1.7.0 h1:7lJfhqlPssTb1WQx4yvTHN0uElPEv52sbaECrAQxjAo=
+github.com/dlclark/regexp2 v1.7.0/go.mod h1:DHkYz0B9wPfa6wondMfaivmHpzrQ3v9q8cnmRbL6yW8=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=

otto.go

@@ -225,6 +225,7 @@ import (
 	"strings"
 
 	"github.com/robertkrimen/otto/file"
+	"github.com/robertkrimen/otto/regexp"
 	"github.com/robertkrimen/otto/registry"
 )
 
@@ -237,11 +238,60 @@ type Otto struct {
 	runtime   *runtime
 }
 
+// Option represents a Otto configuration option.
+type Option func(*Otto)
+
+// Debugger is an option that sets the debugger handler to fn.
+func Debugger(fn func(vm *Otto)) Option {
+	return func(o *Otto) {
+		o.runtime.debugger = fn
+	}
+}
+
+// RandomSource is an option that sets the random source to fn.
+func RandomSource(fn func() float64) Option {
+	return func(o *Otto) {
+		o.runtime.random = fn
+	}
+}
+
+// Stack is an option that sets the stack depth to limit.
+// Default: 0 (unlimited).
+func Stack(limit int) Option {
+	return func(o *Otto) {
+		o.runtime.stackLimit = limit
+	}
+}
+
+// StackTrace is an option that sets the stack trace depth to limit.
+// Default: 10.
+func StackTrace(limit int) Option {
+	return func(o *Otto) {
+		o.runtime.traceLimit = limit
+	}
+}
+
+// RegExp is an option which sets the regular expression engine.
+// This can be used to enable ECMAScript compatible regular expression
+// processing using regexp2.Creator.
+// Default: standard regexp library using ECMA to RE2 transformation
+// which provides constant order matching but doesn't support backtracking.
+func RegExp(creator regexp.Creator) Option {
+	return func(o *Otto) {
+		o.runtime.regExp = creator
+	}
+}
+
 // New will allocate a new JavaScript runtime.
-func New() *Otto {
+func New(options ...Option) *Otto {
 	o := &Otto{
 		runtime: newContext(),
 	}
+	o.runtime.regExp = &regexpStd{}
+
+	for _, f := range options {
+		f(o)
+	}
 	o.runtime.otto = o
 	o.runtime.traceLimit = 10
 	if err := o.Set("console", o.runtime.newConsole()); err != nil {
@@ -360,11 +410,13 @@ func (o Otto) setValue(name string, value Value) {
 }
 
 // SetDebuggerHandler sets the debugger handler to fn.
+// Deprecated: Use Debugger option.
 func (o Otto) SetDebuggerHandler(fn func(vm *Otto)) {
 	o.runtime.debugger = fn
 }
 
 // SetRandomSource sets the random source to fn.
+// Deprecated: Use RandomSource option.
 func (o Otto) SetRandomSource(fn func() float64) {
 	o.runtime.random = fn
 }
@@ -377,6 +429,7 @@ func (o Otto) SetRandomSource(fn func() float64) {
 // JavaScript makes a call to a Go function, otto won't keep track of what
 // happens outside the interpreter. So if your Go function is infinitely
 // recursive, you're still in trouble.
+// Deprecated: Use Stack option.
 func (o Otto) SetStackDepthLimit(limit int) {
 	o.runtime.stackLimit = limit
 }
@@ -386,6 +439,7 @@ func (o Otto) SetStackDepthLimit(limit int) {
 // is 10. This is consistent with V8 and SpiderMonkey.
 //
 // TODO: expose via `Error.stackTraceLimit`.
+// Deprecated: Use StackTrace option.
 func (o Otto) SetStackTraceLimit(limit int) {
 	o.runtime.traceLimit = limit
 }

parser/expression.go

@@ -142,21 +142,24 @@ func (p *_parser) parseRegExpLiteral() *ast.RegExpLiteral {
 
 	var value string
 	// TODO 15.10
-	// Test during parsing that this is a valid regular expression
-	// Sorry, (?=) and (?!) are invalid (for now)
-	pat, err := TransformRegExp(pattern)
-	if err != nil {
-		if pat == "" || p.mode&IgnoreRegExpErrors == 0 {
-			p.error(idx, "Invalid regular expression: %s", err.Error())
-		}
-	} else {
-		_, err = regexp.Compile(pat)
+	if p.mode&NoRegExpTransform == 0 {
+		// Test during parsing that this is a valid regular expression
+		// Sorry, (?=) and (?!) are invalid (for now)
+		pat, err := TransformRegExp(pattern)
 		if err != nil {
-			// We should not get here, ParseRegExp should catch any errors
-			p.error(idx, "Invalid regular expression: %s", err.Error()[22:]) // Skip redundant "parse regexp error"
+			if pat == "" || p.mode&IgnoreRegExpErrors == 0 {
+				p.error(idx, "Invalid regular expression: %s", err.Error())
+			}
 		} else {
-			value = pat
+			if _, err = regexp.Compile(pat); err != nil {
+				// We should not get here, ParseRegExp should catch any errors
+				p.error(idx, "Invalid regular expression: %s", err.Error()[22:]) // Skip redundant "parse regexp error"
+			} else {
+				value = pat
+			}
 		}
+	} else {
+		value = pattern
 	}
 
 	literal := p.str[offset:endOffset]

parser/parser.go

@@ -54,6 +54,9 @@ const (
 
 	// StoreComments stores the comments from source to the comments map.
 	StoreComments
+
+	// NoRegExpTransform disables RegExp transformation.
+	NoRegExpTransform
 )
 
 type _parser struct { //nolint: maligned

parser/regexp.go

@@ -39,7 +39,6 @@ func TransformRegExp(pattern string) (string, error) {
 	}
 
 	// TODO If without \, if without (?=, (?!, then another shortcut
-
 	parser := regExpParser{
 		str:      pattern,
 		length:   len(pattern),

regexp/interfaces.go

@@ -0,0 +1,45 @@
+// Package regexp defines Regular Expression interfaces used for otto.
+package regexp
+
+// Finder is implemented by types which can act as a regular expression finder.
+type Finder interface {
+	// FindStringIndex returns a two-element slice of integers defining the location of the
+	// leftmost match in s of the regular expression. The match itself is at s[loc[0]:loc[1]].
+	// A return value of nil indicates no match.
+	FindStringIndex(s string) []int
+
+	// FindAllStringIndex is the 'All' version of FindStringIndex; it returns a slice of all
+	// successive matches of the expression, as defined by the 'All' description in the package
+	// comment. A return value of nil indicates no match.
+	FindAllStringIndex(s string, n int) [][]int
+
+	// FindStringSubmatchIndex returns a slice holding the index pairs identifying the leftmost
+	// match of the regular expression in s and the matches, if any, of its sub expressions, as
+	// defined by the 'Submatch' and 'Index' descriptions in the package comment. A return value
+	// of nil indicates no match.
+	FindStringSubmatchIndex(s string) []int
+
+	// FindAllStringSubmatchIndex is the 'All' version of FindStringSubmatchIndex; it returns a
+	// slice of all successive matches of the expression, as defined by the 'All' description in
+	// the package comment. A return value of nil indicates no match.
+	FindAllStringSubmatchIndex(s string, n int) [][]int
+
+	// FindAllSubmatchIndex is the 'All' version of FindSubmatchIndex; it returns a slice of all
+	// successive matches of the expression, as defined by the 'All' description in the package
+	// comment. A return value of nil indicates no match.
+	FindAllSubmatchIndex(b []byte, n int) [][]int
+}
+
+// Creator is implemented by types which can operate a RegExp provider for otto.
+type Creator interface {
+	// Compile parses a regular expression and returns, if successful, a Finder that
+	// can be used to match against text.
+	Compile(str string) (Finder, error)
+
+	// MustCompile is like Compile but panics if the expression cannot be parsed. It simplifies safe
+	// initialization of global variables holding compiled regular expressions.
+	MustCompile(str string) Finder
+
+	// NoTransform returns true if no RegExp transformation should be done.
+	NoTransform() bool
+}