// Returns a generator that will run the generator for r's sub-expression [min, max] times.
func createRepeatingGenerator(regexp *syntax.Regexp, genArgs *GeneratorArgs, min, max int) (*internalGenerator, error) {
if err := enforceSingleSub(regexp); err != nil {
return nil, err
}
generator, err := newGenerator(regexp.Sub[0], genArgs)
if err != nil {
return nil, generatorError(err, "failed to create generator for subexpression: /%s/", regexp)
}
if min == noBound {
min = int(genArgs.MinUnboundedRepeatCount)
}
if max == noBound {
max = int(genArgs.MaxUnboundedRepeatCount)
}
return &internalGenerator{regexp.String(), func() string {
n := min + genArgs.rng.Intn(max-min+1)
var result bytes.Buffer
for i := 0; i < n; i++ {
result.WriteString(generator.Generate())
}
return result.String()
}}, nil
}
// Create a new generator for r.
func newGenerator(regexp *syntax.Regexp, args *GeneratorArgs) (generator *internalGenerator, err error) {
simplified := regexp.Simplify()
factory, ok := generatorFactories[simplified.Op]
if ok {
return factory(simplified, args)
}
return nil, fmt.Errorf("invalid generator pattern: /%s/ as /%s/\n%s",
regexp, simplified, inspectRegexpToString(simplified))
}
func opConcat(regexp *syntax.Regexp, genArgs *GeneratorArgs) (*internalGenerator, error) {
enforceOp(regexp, syntax.OpConcat)
generators, err := newGenerators(regexp.Sub, genArgs)
if err != nil {
return nil, generatorError(err, "error creating generators for concat pattern /%s/", regexp)
}
return &internalGenerator{regexp.String(), func() string {
return genArgs.Executor.Execute(generators)
}}, nil
}
func singleLiteralToCharClass(rx *syntax.Regexp) {
if rx.Op == syntax.OpLiteral && len(rx.Rune) == 1 {
char := rx.Rune[0]
if rx.Flags&syntax.FoldCase != 0 && unicode.ToLower(char) != unicode.ToUpper(char) {
l, h := unicode.ToLower(char), unicode.ToUpper(char)
rx.Rune = []rune{h, h, l, l}
rx.Rune0 = [...]rune{h, h}
} else {
rx.Rune = []rune{char, char}
rx.Rune0 = [...]rune{char, char}
}
rx.Op = syntax.OpCharClass
}
}
func opConcat(regexp *syntax.Regexp, genArgs *GeneratorArgs) (*internalGenerator, error) {
enforceOp(regexp, syntax.OpConcat)
generators, err := newGenerators(regexp.Sub, genArgs)
if err != nil {
return nil, generatorError(err, "error creating generators for concat pattern /%s/", regexp)
}
return &internalGenerator{regexp.String(), func() string {
var result bytes.Buffer
for _, generator := range generators {
result.WriteString(generator.Generate())
}
return result.String()
}}, nil
}
func opAlternate(regexp *syntax.Regexp, genArgs *GeneratorArgs) (*internalGenerator, error) {
enforceOp(regexp, syntax.OpAlternate)
generators, err := newGenerators(regexp.Sub, genArgs)
if err != nil {
return nil, generatorError(err, "error creating generators for alternate pattern /%s/", regexp)
}
numGens := len(generators)
return &internalGenerator{regexp.String(), func() string {
i := genArgs.rng.Intn(numGens)
generator := generators[i]
return generator.Generate()
}}, nil
}
// Returns a generator that will run the generator for r's sub-expression [min, max] times.
func createRepeatingGenerator(regexp *syntax.Regexp, genArgs *GeneratorArgs, min int, max int) (*internalGenerator, error) {
if err := enforceSingleSub(regexp); err != nil {
return nil, err
}
generator, err := newGenerator(regexp.Sub[0], genArgs)
if err != nil {
return nil, generatorError(err, "failed to create generator for subexpression: /%s/", regexp)
}
if max < 0 {
max = maxUpperBound
}
return &internalGenerator{regexp.String(), func() string {
n := min + genArgs.rng.Intn(max-min+1)
return executeGeneratorRepeatedly(genArgs.Executor, generator, n)
}}, nil
}
func opCapture(regexp *syntax.Regexp, args *GeneratorArgs) (*internalGenerator, error) {
enforceOp(regexp, syntax.OpCapture)
if err := enforceSingleSub(regexp); err != nil {
return nil, err
}
groupRegexp := regexp.Sub[0]
generator, err := newGenerator(groupRegexp, args)
if err != nil {
return nil, err
}
// Group indices are 0-based, but index 0 is the whole expression.
index := regexp.Cap - 1
return &internalGenerator{regexp.String(), func() string {
return args.CaptureGroupHandler(index, regexp.Name, groupRegexp, generator, args)
}}, nil
}
func compileSyntax(re *syntax.Regexp, expr string, longest bool) (*Regexp, error) {
maxCap := re.MaxCap()
capNames := re.CapNames()
re = re.Simplify()
prog, err := syntax.Compile(re)
if err != nil {
return nil, err
}
regexp := &Regexp{
expr: expr,
prog: prog,
onepass: compileOnePass(prog),
numSubexp: maxCap,
subexpNames: capNames,
cond: prog.StartCond(),
longest: longest,
}
if regexp.onepass == notOnePass {
regexp.prefix, regexp.prefixComplete = prog.Prefix()
} else {
regexp.prefix, regexp.prefixComplete, regexp.prefixEnd = onePassPrefix(prog)
}
if regexp.prefix != "" {
// TODO(rsc): Remove this allocation by adding
// IndexString to package bytes.
regexp.prefixBytes = []byte(regexp.prefix)
regexp.prefixRune, _ = utf8.DecodeRuneInString(regexp.prefix)
}
return regexp, nil
}
func TestCompileOnePass(t *testing.T) {
var (
p *syntax.Prog
re *syntax.Regexp
err error
)
for _, test := range onePassTests {
if re, err = syntax.Parse(test.re, syntax.Perl); err != nil {
t.Errorf("Parse(%q) got err:%s, want success", test.re, err)
continue
}
// needs to be done before compile...
re = re.Simplify()
if p, err = syntax.Compile(re); err != nil {
t.Errorf("Compile(%q) got err:%s, want success", test.re, err)
continue
}
onePass = compileOnePass(p)
if (onePass == notOnePass) != (test.onePass == notOnePass) {
t.Errorf("CompileOnePass(%q) got %v, expected %v", test.re, onePass, test.onePass)
}
}
}
// transform replaces each node in a regex AST with the return value of the given function
// it processes the children of a node before the node itself
func transform(expr *syntax.Regexp, f transformer) (*syntax.Regexp, error) {
var newchildren []*syntax.Regexp
for _, child := range expr.Sub {
newchild, err := transform(child, f)
if err != nil {
return nil, err
}
replacements, err := f(newchild)
if err != nil {
return nil, err
}
newchildren = append(newchildren, replacements...)
}
expr.Sub = newchildren
return expr, nil
}
// CompileSyntax is like Compile but takes a syntax tree as input.
func CompileSyntax(ast *syntax.Regexp) (*Regexp, error) {
return compileSyntax(ast, ast.String(), true)
}
// Generator that does nothing.
func noop(regexp *syntax.Regexp, args *GeneratorArgs) (*internalGenerator, error) {
return &internalGenerator{regexp.String(), func() string {
return ""
}}, nil
}
func opEmptyMatch(regexp *syntax.Regexp, args *GeneratorArgs) (*internalGenerator, error) {
enforceOp(regexp, syntax.OpEmptyMatch)
return &internalGenerator{regexp.String(), func() string {
return ""
}}, nil
}
// Handles syntax.ClassNL because the parser uses that flag to generate character
// classes that respect it.
func opCharClass(regexp *syntax.Regexp, args *GeneratorArgs) (*internalGenerator, error) {
enforceOp(regexp, syntax.OpCharClass)
charClass := parseCharClass(regexp.Rune)
return createCharClassGenerator(regexp.String(), charClass, args)
}
func opAnyCharNotNl(regexp *syntax.Regexp, args *GeneratorArgs) (*internalGenerator, error) {
enforceOp(regexp, syntax.OpAnyCharNotNL)
charClass := newCharClass(1, rune(math.MaxInt32))
return createCharClassGenerator(regexp.String(), charClass, args)
}
func opAnyChar(regexp *syntax.Regexp, args *GeneratorArgs) (*internalGenerator, error) {
enforceOp(regexp, syntax.OpAnyChar)
return &internalGenerator{regexp.String(), func() string {
return runesToString(rune(args.rng.Int31()))
}}, nil
}
func opLiteral(regexp *syntax.Regexp, args *GeneratorArgs) (*internalGenerator, error) {
enforceOp(regexp, syntax.OpLiteral)
return &internalGenerator{regexp.String(), func() string {
return runesToString(regexp.Rune...)
}}, nil
}
