cpp/common/include/rapidjson/internal/regex.h
// Tencent is pleased to support the open source community by making RapidJSON available.
//
// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
//
// Licensed under the MIT License (the "License"); you may not use this file except
// in compliance with the License. You may obtain a copy of the License at
//
// http://opensource.org/licenses/MIT
//
// Unless required by applicable law or agreed to in writing, software distributed
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
// specific language governing permissions and limitations under the License.
#ifndef RAPIDJSON_INTERNAL_REGEX_H_
#define RAPIDJSON_INTERNAL_REGEX_H_
#include "../allocators.h"
#include "../stream.h"
#include "stack.h"
#ifdef __clang__
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(padded)
RAPIDJSON_DIAG_OFF(switch-enum)
RAPIDJSON_DIAG_OFF(implicit-fallthrough)
#endif
#ifdef __GNUC__
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(effc++)
#endif
#ifdef _MSC_VER
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(4512) // assignment operator could not be generated
#endif
#ifndef RAPIDJSON_REGEX_VERBOSE
#define RAPIDJSON_REGEX_VERBOSE 0
#endif
RAPIDJSON_NAMESPACE_BEGIN
namespace internal {
///////////////////////////////////////////////////////////////////////////////
// GenericRegex
static const SizeType kRegexInvalidState = ~SizeType(0); //!< Represents an invalid index in GenericRegex::State::out, out1
static const SizeType kRegexInvalidRange = ~SizeType(0);
//! Regular expression engine with subset of ECMAscript grammar.
/*!
Supported regular expression syntax:
- \c ab Concatenation
- \c a|b Alternation
- \c a? Zero or one
- \c a* Zero or more
- \c a+ One or more
- \c a{3} Exactly 3 times
- \c a{3,} At least 3 times
- \c a{3,5} 3 to 5 times
- \c (ab) Grouping
- \c ^a At the beginning
- \c a$ At the end
- \c . Any character
- \c [abc] Character classes
- \c [a-c] Character class range
- \c [a-z0-9_] Character class combination
- \c [^abc] Negated character classes
- \c [^a-c] Negated character class range
- \c [\b] Backspace (U+0008)
- \c \\| \\\\ ... Escape characters
- \c \\f Form feed (U+000C)
- \c \\n Line feed (U+000A)
- \c \\r Carriage return (U+000D)
- \c \\t Tab (U+0009)
- \c \\v Vertical tab (U+000B)
\note This is a Thompson NFA engine, implemented with reference to
Cox, Russ. "Regular Expression Matching Can Be Simple And Fast (but is slow in Java, Perl, PHP, Python, Ruby,...).",
https://swtch.com/~rsc/regexp/regexp1.html
*/
template <typename Encoding, typename Allocator = CrtAllocator>
class GenericRegex {
public:
typedef typename Encoding::Ch Ch;
GenericRegex(const Ch* source, Allocator* allocator = 0) :
states_(allocator, 256), ranges_(allocator, 256), root_(kRegexInvalidState), stateCount_(), rangeCount_(),
stateSet_(), state0_(allocator, 0), state1_(allocator, 0), anchorBegin_(), anchorEnd_()
{
GenericStringStream<Encoding> ss(source);
DecodedStream<GenericStringStream<Encoding> > ds(ss);
Parse(ds);
}
~GenericRegex() {
Allocator::Free(stateSet_);
}
bool IsValid() const {
return root_ != kRegexInvalidState;
}
template <typename InputStream>
bool Match(InputStream& is) const {
return SearchWithAnchoring(is, true, true);
}
bool Match(const Ch* s) const {
GenericStringStream<Encoding> is(s);
return Match(is);
}
template <typename InputStream>
bool Search(InputStream& is) const {
return SearchWithAnchoring(is, anchorBegin_, anchorEnd_);
}
bool Search(const Ch* s) const {
GenericStringStream<Encoding> is(s);
return Search(is);
}
private:
enum Operator {
kZeroOrOne,
kZeroOrMore,
kOneOrMore,
kConcatenation,
kAlternation,
kLeftParenthesis
};
static const unsigned kAnyCharacterClass = 0xFFFFFFFF; //!< For '.'
static const unsigned kRangeCharacterClass = 0xFFFFFFFE;
static const unsigned kRangeNegationFlag = 0x80000000;
struct Range {
unsigned start; //
unsigned end;
SizeType next;
};
struct State {
SizeType out; //!< Equals to kInvalid for matching state
SizeType out1; //!< Equals to non-kInvalid for split
SizeType rangeStart;
unsigned codepoint;
};
struct Frag {
Frag(SizeType s, SizeType o, SizeType m) : start(s), out(o), minIndex(m) {}
SizeType start;
SizeType out; //!< link-list of all output states
SizeType minIndex;
};
template <typename SourceStream>
class DecodedStream {
public:
DecodedStream(SourceStream& ss) : ss_(ss), codepoint_() { Decode(); }
unsigned Peek() { return codepoint_; }
unsigned Take() {
unsigned c = codepoint_;
if (c) // No further decoding when '\0'
Decode();
return c;
}
private:
void Decode() {
if (!Encoding::Decode(ss_, &codepoint_))
codepoint_ = 0;
}
SourceStream& ss_;
unsigned codepoint_;
};
State& GetState(SizeType index) {
RAPIDJSON_ASSERT(index < stateCount_);
return states_.template Bottom<State>()[index];
}
const State& GetState(SizeType index) const {
RAPIDJSON_ASSERT(index < stateCount_);
return states_.template Bottom<State>()[index];
}
Range& GetRange(SizeType index) {
RAPIDJSON_ASSERT(index < rangeCount_);
return ranges_.template Bottom<Range>()[index];
}
const Range& GetRange(SizeType index) const {
RAPIDJSON_ASSERT(index < rangeCount_);
return ranges_.template Bottom<Range>()[index];
}
template <typename InputStream>
void Parse(DecodedStream<InputStream>& ds) {
Allocator allocator;
Stack<Allocator> operandStack(&allocator, 256); // Frag
Stack<Allocator> operatorStack(&allocator, 256); // Operator
Stack<Allocator> atomCountStack(&allocator, 256); // unsigned (Atom per parenthesis)
*atomCountStack.template Push<unsigned>() = 0;
unsigned codepoint;
while (ds.Peek() != 0) {
switch (codepoint = ds.Take()) {
case '^':
anchorBegin_ = true;
break;
case '$':
anchorEnd_ = true;
break;
case '|':
while (!operatorStack.Empty() && *operatorStack.template Top<Operator>() < kAlternation)
if (!Eval(operandStack, *operatorStack.template Pop<Operator>(1)))
return;
*operatorStack.template Push<Operator>() = kAlternation;
*atomCountStack.template Top<unsigned>() = 0;
break;
case '(':
*operatorStack.template Push<Operator>() = kLeftParenthesis;
*atomCountStack.template Push<unsigned>() = 0;
break;
case ')':
while (!operatorStack.Empty() && *operatorStack.template Top<Operator>() != kLeftParenthesis)
if (!Eval(operandStack, *operatorStack.template Pop<Operator>(1)))
return;
if (operatorStack.Empty())
return;
operatorStack.template Pop<Operator>(1);
atomCountStack.template Pop<unsigned>(1);
ImplicitConcatenation(atomCountStack, operatorStack);
break;
case '?':
if (!Eval(operandStack, kZeroOrOne))
return;
break;
case '*':
if (!Eval(operandStack, kZeroOrMore))
return;
break;
case '+':
if (!Eval(operandStack, kOneOrMore))
return;
break;
case '{':
{
unsigned n, m;
if (!ParseUnsigned(ds, &n))
return;
if (ds.Peek() == ',') {
ds.Take();
if (ds.Peek() == '}')
m = kInfinityQuantifier;
else if (!ParseUnsigned(ds, &m) || m < n)
return;
}
else
m = n;
if (!EvalQuantifier(operandStack, n, m) || ds.Peek() != '}')
return;
ds.Take();
}
break;
case '.':
PushOperand(operandStack, kAnyCharacterClass);
ImplicitConcatenation(atomCountStack, operatorStack);
break;
case '[':
{
SizeType range;
if (!ParseRange(ds, &range))
return;
SizeType s = NewState(kRegexInvalidState, kRegexInvalidState, kRangeCharacterClass);
GetState(s).rangeStart = range;
*operandStack.template Push<Frag>() = Frag(s, s, s);
}
ImplicitConcatenation(atomCountStack, operatorStack);
break;
case '\\': // Escape character
if (!CharacterEscape(ds, &codepoint))
return; // Unsupported escape character
// fall through to default
default: // Pattern character
PushOperand(operandStack, codepoint);
ImplicitConcatenation(atomCountStack, operatorStack);
}
}
while (!operatorStack.Empty())
if (!Eval(operandStack, *operatorStack.template Pop<Operator>(1)))
return;
// Link the operand to matching state.
if (operandStack.GetSize() == sizeof(Frag)) {
Frag* e = operandStack.template Pop<Frag>(1);
Patch(e->out, NewState(kRegexInvalidState, kRegexInvalidState, 0));
root_ = e->start;
#if RAPIDJSON_REGEX_VERBOSE
printf("root: %d\n", root_);
for (SizeType i = 0; i < stateCount_ ; i++) {
State& s = GetState(i);
printf("[%2d] out: %2d out1: %2d c: '%c'\n", i, s.out, s.out1, (char)s.codepoint);
}
printf("\n");
#endif
}
// Preallocate buffer for SearchWithAnchoring()
RAPIDJSON_ASSERT(stateSet_ == 0);
if (stateCount_ > 0) {
stateSet_ = static_cast<unsigned*>(states_.GetAllocator().Malloc(GetStateSetSize()));
state0_.template Reserve<SizeType>(stateCount_);
state1_.template Reserve<SizeType>(stateCount_);
}
}
SizeType NewState(SizeType out, SizeType out1, unsigned codepoint) {
State* s = states_.template Push<State>();
s->out = out;
s->out1 = out1;
s->codepoint = codepoint;
s->rangeStart = kRegexInvalidRange;
return stateCount_++;
}
void PushOperand(Stack<Allocator>& operandStack, unsigned codepoint) {
SizeType s = NewState(kRegexInvalidState, kRegexInvalidState, codepoint);
*operandStack.template Push<Frag>() = Frag(s, s, s);
}
void ImplicitConcatenation(Stack<Allocator>& atomCountStack, Stack<Allocator>& operatorStack) {
if (*atomCountStack.template Top<unsigned>())
*operatorStack.template Push<Operator>() = kConcatenation;
(*atomCountStack.template Top<unsigned>())++;
}
SizeType Append(SizeType l1, SizeType l2) {
SizeType old = l1;
while (GetState(l1).out != kRegexInvalidState)
l1 = GetState(l1).out;
GetState(l1).out = l2;
return old;
}
void Patch(SizeType l, SizeType s) {
for (SizeType next; l != kRegexInvalidState; l = next) {
next = GetState(l).out;
GetState(l).out = s;
}
}
bool Eval(Stack<Allocator>& operandStack, Operator op) {
switch (op) {
case kConcatenation:
RAPIDJSON_ASSERT(operandStack.GetSize() >= sizeof(Frag) * 2);
{
Frag e2 = *operandStack.template Pop<Frag>(1);
Frag e1 = *operandStack.template Pop<Frag>(1);
Patch(e1.out, e2.start);
*operandStack.template Push<Frag>() = Frag(e1.start, e2.out, Min(e1.minIndex, e2.minIndex));
}
return true;
case kAlternation:
if (operandStack.GetSize() >= sizeof(Frag) * 2) {
Frag e2 = *operandStack.template Pop<Frag>(1);
Frag e1 = *operandStack.template Pop<Frag>(1);
SizeType s = NewState(e1.start, e2.start, 0);
*operandStack.template Push<Frag>() = Frag(s, Append(e1.out, e2.out), Min(e1.minIndex, e2.minIndex));
return true;
}
return false;
case kZeroOrOne:
if (operandStack.GetSize() >= sizeof(Frag)) {
Frag e = *operandStack.template Pop<Frag>(1);
SizeType s = NewState(kRegexInvalidState, e.start, 0);
*operandStack.template Push<Frag>() = Frag(s, Append(e.out, s), e.minIndex);
return true;
}
return false;
case kZeroOrMore:
if (operandStack.GetSize() >= sizeof(Frag)) {
Frag e = *operandStack.template Pop<Frag>(1);
SizeType s = NewState(kRegexInvalidState, e.start, 0);
Patch(e.out, s);
*operandStack.template Push<Frag>() = Frag(s, s, e.minIndex);
return true;
}
return false;
default:
RAPIDJSON_ASSERT(op == kOneOrMore);
if (operandStack.GetSize() >= sizeof(Frag)) {
Frag e = *operandStack.template Pop<Frag>(1);
SizeType s = NewState(kRegexInvalidState, e.start, 0);
Patch(e.out, s);
*operandStack.template Push<Frag>() = Frag(e.start, s, e.minIndex);
return true;
}
return false;
}
}
bool EvalQuantifier(Stack<Allocator>& operandStack, unsigned n, unsigned m) {
RAPIDJSON_ASSERT(n <= m);
RAPIDJSON_ASSERT(operandStack.GetSize() >= sizeof(Frag));
if (n == 0) {
if (m == 0) // a{0} not support
return false;
else if (m == kInfinityQuantifier)
Eval(operandStack, kZeroOrMore); // a{0,} -> a*
else {
Eval(operandStack, kZeroOrOne); // a{0,5} -> a?
for (unsigned i = 0; i < m - 1; i++)
CloneTopOperand(operandStack); // a{0,5} -> a? a? a? a? a?
for (unsigned i = 0; i < m - 1; i++)
Eval(operandStack, kConcatenation); // a{0,5} -> a?a?a?a?a?
}
return true;
}
for (unsigned i = 0; i < n - 1; i++) // a{3} -> a a a
CloneTopOperand(operandStack);
if (m == kInfinityQuantifier)
Eval(operandStack, kOneOrMore); // a{3,} -> a a a+
else if (m > n) {
CloneTopOperand(operandStack); // a{3,5} -> a a a a
Eval(operandStack, kZeroOrOne); // a{3,5} -> a a a a?
for (unsigned i = n; i < m - 1; i++)
CloneTopOperand(operandStack); // a{3,5} -> a a a a? a?
for (unsigned i = n; i < m; i++)
Eval(operandStack, kConcatenation); // a{3,5} -> a a aa?a?
}
for (unsigned i = 0; i < n - 1; i++)
Eval(operandStack, kConcatenation); // a{3} -> aaa, a{3,} -> aaa+, a{3.5} -> aaaa?a?
return true;
}
static SizeType Min(SizeType a, SizeType b) { return a < b ? a : b; }
void CloneTopOperand(Stack<Allocator>& operandStack) {
const Frag src = *operandStack.template Top<Frag>(); // Copy constructor to prevent invalidation
SizeType count = stateCount_ - src.minIndex; // Assumes top operand contains states in [src->minIndex, stateCount_)
State* s = states_.template Push<State>(count);
memcpy(s, &GetState(src.minIndex), count * sizeof(State));
for (SizeType j = 0; j < count; j++) {
if (s[j].out != kRegexInvalidState)
s[j].out += count;
if (s[j].out1 != kRegexInvalidState)
s[j].out1 += count;
}
*operandStack.template Push<Frag>() = Frag(src.start + count, src.out + count, src.minIndex + count);
stateCount_ += count;
}
template <typename InputStream>
bool ParseUnsigned(DecodedStream<InputStream>& ds, unsigned* u) {
unsigned r = 0;
if (ds.Peek() < '0' || ds.Peek() > '9')
return false;
while (ds.Peek() >= '0' && ds.Peek() <= '9') {
if (r >= 429496729 && ds.Peek() > '5') // 2^32 - 1 = 4294967295
return false; // overflow
r = r * 10 + (ds.Take() - '0');
}
*u = r;
return true;
}
template <typename InputStream>
bool ParseRange(DecodedStream<InputStream>& ds, SizeType* range) {
bool isBegin = true;
bool negate = false;
int step = 0;
SizeType start = kRegexInvalidRange;
SizeType current = kRegexInvalidRange;
unsigned codepoint;
while ((codepoint = ds.Take()) != 0) {
if (isBegin) {
isBegin = false;
if (codepoint == '^') {
negate = true;
continue;
}
}
switch (codepoint) {
case ']':
if (start == kRegexInvalidRange)
return false; // Error: nothing inside []
if (step == 2) { // Add trailing '-'
SizeType r = NewRange('-');
RAPIDJSON_ASSERT(current != kRegexInvalidRange);
GetRange(current).next = r;
}
if (negate)
GetRange(start).start |= kRangeNegationFlag;
*range = start;
return true;
case '\\':
if (ds.Peek() == 'b') {
ds.Take();
codepoint = 0x0008; // Escape backspace character
}
else if (!CharacterEscape(ds, &codepoint))
return false;
// fall through to default
default:
switch (step) {
case 1:
if (codepoint == '-') {
step++;
break;
}
// fall through to step 0 for other characters
case 0:
{
SizeType r = NewRange(codepoint);
if (current != kRegexInvalidRange)
GetRange(current).next = r;
if (start == kRegexInvalidRange)
start = r;
current = r;
}
step = 1;
break;
default:
RAPIDJSON_ASSERT(step == 2);
GetRange(current).end = codepoint;
step = 0;
}
}
}
return false;
}
SizeType NewRange(unsigned codepoint) {
Range* r = ranges_.template Push<Range>();
r->start = r->end = codepoint;
r->next = kRegexInvalidRange;
return rangeCount_++;
}
template <typename InputStream>
bool CharacterEscape(DecodedStream<InputStream>& ds, unsigned* escapedCodepoint) {
unsigned codepoint;
switch (codepoint = ds.Take()) {
case '^':
case '$':
case '|':
case '(':
case ')':
case '?':
case '*':
case '+':
case '.':
case '[':
case ']':
case '{':
case '}':
case '\\':
*escapedCodepoint = codepoint; return true;
case 'f': *escapedCodepoint = 0x000C; return true;
case 'n': *escapedCodepoint = 0x000A; return true;
case 'r': *escapedCodepoint = 0x000D; return true;
case 't': *escapedCodepoint = 0x0009; return true;
case 'v': *escapedCodepoint = 0x000B; return true;
default:
return false; // Unsupported escape character
}
}
template <typename InputStream>
bool SearchWithAnchoring(InputStream& is, bool anchorBegin, bool anchorEnd) const {
RAPIDJSON_ASSERT(IsValid());
DecodedStream<InputStream> ds(is);
state0_.Clear();
Stack<Allocator> *current = &state0_, *next = &state1_;
const size_t stateSetSize = GetStateSetSize();
std::memset(stateSet_, 0, stateSetSize);
bool matched = AddState(*current, root_);
unsigned codepoint;
while (!current->Empty() && (codepoint = ds.Take()) != 0) {
std::memset(stateSet_, 0, stateSetSize);
next->Clear();
matched = false;
for (const SizeType* s = current->template Bottom<SizeType>(); s != current->template End<SizeType>(); ++s) {
const State& sr = GetState(*s);
if (sr.codepoint == codepoint ||
sr.codepoint == kAnyCharacterClass ||
(sr.codepoint == kRangeCharacterClass && MatchRange(sr.rangeStart, codepoint)))
{
matched = AddState(*next, sr.out) || matched;
if (!anchorEnd && matched)
return true;
}
if (!anchorBegin)
AddState(*next, root_);
}
internal::Swap(current, next);
}
return matched;
}
size_t GetStateSetSize() const {
return (stateCount_ + 31) / 32 * 4;
}
// Return whether the added states is a match state
bool AddState(Stack<Allocator>& l, SizeType index) const {
RAPIDJSON_ASSERT(index != kRegexInvalidState);
const State& s = GetState(index);
if (s.out1 != kRegexInvalidState) { // Split
bool matched = AddState(l, s.out);
return AddState(l, s.out1) || matched;
}
else if (!(stateSet_[index >> 5] & (1 << (index & 31)))) {
stateSet_[index >> 5] |= (1 << (index & 31));
*l.template PushUnsafe<SizeType>() = index;
}
return s.out == kRegexInvalidState; // by using PushUnsafe() above, we can ensure s is not validated due to reallocation.
}
bool MatchRange(SizeType rangeIndex, unsigned codepoint) const {
bool yes = (GetRange(rangeIndex).start & kRangeNegationFlag) == 0;
while (rangeIndex != kRegexInvalidRange) {
const Range& r = GetRange(rangeIndex);
if (codepoint >= (r.start & ~kRangeNegationFlag) && codepoint <= r.end)
return yes;
rangeIndex = r.next;
}
return !yes;
}
Stack<Allocator> states_;
Stack<Allocator> ranges_;
SizeType root_;
SizeType stateCount_;
SizeType rangeCount_;
static const unsigned kInfinityQuantifier = ~0u;
// For SearchWithAnchoring()
uint32_t* stateSet_; // allocated by states_.GetAllocator()
mutable Stack<Allocator> state0_;
mutable Stack<Allocator> state1_;
bool anchorBegin_;
bool anchorEnd_;
};
typedef GenericRegex<UTF8<> > Regex;
} // namespace internal
RAPIDJSON_NAMESPACE_END
#ifdef __clang__
RAPIDJSON_DIAG_POP
#endif
#ifdef _MSC_VER
RAPIDJSON_DIAG_POP
#endif
#endif // RAPIDJSON_INTERNAL_REGEX_H_