src/regexp-macro-assembler.cc

// Copyright 2008 the V8 project authors. All rights reserved.
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#include "v8.h"
#include "ast.h"
#include "assembler.h"
#include "regexp-stack.h"
#include "regexp-macro-assembler.h"

namespace v8 {
namespace internal {

RegExpMacroAssembler::RegExpMacroAssembler() {
}


RegExpMacroAssembler::~RegExpMacroAssembler() {
}


#ifdef V8_NATIVE_REGEXP  // Avoid unused code, e.g., on ARM.

NativeRegExpMacroAssembler::NativeRegExpMacroAssembler() {
}


NativeRegExpMacroAssembler::~NativeRegExpMacroAssembler() {
}

const byte* NativeRegExpMacroAssembler::StringCharacterPosition(
    String* subject,
    int start_index) {
  // Not just flat, but ultra flat.
  ASSERT(subject->IsExternalString() || subject->IsSeqString());
  ASSERT(start_index >= 0);
  ASSERT(start_index <= subject->length());
  if (subject->IsAsciiRepresentation()) {
    const byte* address;
    if (StringShape(subject).IsExternal()) {
      const char* data = ExternalAsciiString::cast(subject)->resource()->data();
      address = reinterpret_cast<const byte*>(data);
    } else {
      ASSERT(subject->IsSeqAsciiString());
      char* data = SeqAsciiString::cast(subject)->GetChars();
      address = reinterpret_cast<const byte*>(data);
    }
    return address + start_index;
  }
  const uc16* data;
  if (StringShape(subject).IsExternal()) {
    data = ExternalTwoByteString::cast(subject)->resource()->data();
  } else {
    ASSERT(subject->IsSeqTwoByteString());
    data = SeqTwoByteString::cast(subject)->GetChars();
  }
  return reinterpret_cast<const byte*>(data + start_index);
}


NativeRegExpMacroAssembler::Result NativeRegExpMacroAssembler::Match(
    Handle<Code> regexp_code,
    Handle<String> subject,
    int* offsets_vector,
    int offsets_vector_length,
    int previous_index) {

  ASSERT(subject->IsFlat());
  ASSERT(previous_index >= 0);
  ASSERT(previous_index <= subject->length());

  // No allocations before calling the regexp, but we can't use
  // AssertNoAllocation, since regexps might be preempted, and another thread
  // might do allocation anyway.

  String* subject_ptr = *subject;
  // Character offsets into string.
  int start_offset = previous_index;
  int end_offset = subject_ptr->length();

  bool is_ascii = subject->IsAsciiRepresentation();

  if (StringShape(subject_ptr).IsCons()) {
    subject_ptr = ConsString::cast(subject_ptr)->first();
  } else if (StringShape(subject_ptr).IsSliced()) {
    SlicedString* slice = SlicedString::cast(subject_ptr);
    start_offset += slice->start();
    end_offset += slice->start();
    subject_ptr = slice->buffer();
  }
  // Ensure that an underlying string has the same ascii-ness.
  ASSERT(subject_ptr->IsAsciiRepresentation() == is_ascii);
  ASSERT(subject_ptr->IsExternalString() || subject_ptr->IsSeqString());
  // String is now either Sequential or External
  int char_size_shift = is_ascii ? 0 : 1;
  int char_length = end_offset - start_offset;

  const byte* input_start =
      StringCharacterPosition(subject_ptr, start_offset);
  int byte_length = char_length << char_size_shift;
  const byte* input_end = input_start + byte_length;
  Result res = Execute(*regexp_code,
                       subject_ptr,
                       start_offset,
                       input_start,
                       input_end,
                       offsets_vector,
                       previous_index == 0);

  if (res == SUCCESS) {
    // Capture values are relative to start_offset only.
    // Convert them to be relative to start of string.
    for (int i = 0; i < offsets_vector_length; i++) {
      if (offsets_vector[i] >= 0) {
        offsets_vector[i] += previous_index;
      }
    }
  }

  return res;
}


NativeRegExpMacroAssembler::Result NativeRegExpMacroAssembler::Execute(
    Code* code,
    String* input,
    int start_offset,
    const byte* input_start,
    const byte* input_end,
    int* output,
    bool at_start) {
  typedef int (*matcher)(String*, int, const byte*,
                         const byte*, int*, int, Address);
  matcher matcher_func = FUNCTION_CAST<matcher>(code->entry());

  int at_start_val = at_start ? 1 : 0;

  // Ensure that the minimum stack has been allocated.
  RegExpStack stack;
  Address stack_base = RegExpStack::stack_base();

  int result = matcher_func(input,
                            start_offset,
                            input_start,
                            input_end,
                            output,
                            at_start_val,
                            stack_base);
  ASSERT(result <= SUCCESS);
  ASSERT(result >= RETRY);

  if (result == EXCEPTION && !Top::has_pending_exception()) {
    // We detected a stack overflow (on the backtrack stack) in RegExp code,
    // but haven't created the exception yet.
    Top::StackOverflow();
  }
  return static_cast<Result>(result);
}


static unibrow::Mapping<unibrow::Ecma262Canonicalize> canonicalize;

int NativeRegExpMacroAssembler::CaseInsensitiveCompareUC16(
    Address byte_offset1,
    Address byte_offset2,
    size_t byte_length) {
  // This function is not allowed to cause a garbage collection.
  // A GC might move the calling generated code and invalidate the
  // return address on the stack.
  ASSERT(byte_length % 2 == 0);
  uc16* substring1 = reinterpret_cast<uc16*>(byte_offset1);
  uc16* substring2 = reinterpret_cast<uc16*>(byte_offset2);
  size_t length = byte_length >> 1;

  for (size_t i = 0; i < length; i++) {
    unibrow::uchar c1 = substring1[i];
    unibrow::uchar c2 = substring2[i];
    if (c1 != c2) {
      unibrow::uchar s1[1] = { c1 };
      canonicalize.get(c1, '\0', s1);
      if (s1[0] != c2) {
        unibrow::uchar s2[1] = { c2 };
        canonicalize.get(c2, '\0', s2);
        if (s1[0] != s2[0]) {
          return 0;
        }
      }
    }
  }
  return 1;
}

#endif  // V8_NATIVE_REGEXP
} }  // namespace v8::internal