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cre2.cpp
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cre2.cpp
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#include <re2/re2.h>
#include <string>
#include <iostream>
#include <vector>
using namespace std;
static int maxMemoryBudget = 128 << 20; // 128 MiB
typedef struct {
int start;
int end;
} Range;
typedef struct {
bool hasMatch;
int numGroups;
Range* ranges;
} REMatchResult;
/**
* A multi match object which contains either:
* - A list of group matches (individual groups)
* - A list of regular matches (one group per match)
*/
typedef struct {
/**
* Length of either groupMatches or matches (depending on value of hasGroupMatches)
*/
int numMatches;
/**
* If this result contains group matches, contains the number of groups,
* i.e. the number of elements in every groupMatches element.
* Undefined if groupMatches == NULL
* At least one (in case )
*/
int numElements;
/**
* Match ranges
*/
Range** ranges;
} REMultiMatchResult;
//clrsb: Number of leading bits equal to the sign bit (which we set to 0)
//clrsb(~b) - clrsb(0) + 8: Number of leading one bits in the byte b
#define count_leading_ones(b) __builtin_clrsb(~(char)(b)) - __builtin_clrsb(0) + 8
/**
* Builds a lookup table (LUT) that allows mapping a cstring (memory) index
* of a string to lookup (key: cstring coordinate) the character index in a UTF8 string.
*
* Example: abcödef -> 0 1 2 3 3 4 5 6
* @param s The string to map
* @param len The length of s
* @return a new[]-allocated int array of size len, containing the LUT
*/
int* buildUTF8IndexLUT(const char* s, size_t len) {
int* lut = new int[len + 1];
int sidx = 0; // Index in the LUT
for(unsigned int i = 0 ; i < len ; i++) { // i = Current index in s
if((s[i] & 0x80) == 0) { //Single-byte character
lut[i] = sidx;
sidx++;
} else { //Start of multibyte. This branch handles the entire multibyte
int multibyteSize = count_leading_ones(s[i]);
//Set the next <multibyteSize> LUT entries to the current sidx
for(unsigned int j = i; j < multibyteSize + i; j++) {
lut[j] = sidx;
}
//Advance i to after the multibyte, but advance sidx by only 1
// as the multibyte is treated as a single character
i += multibyteSize - 1;
sidx++;
}
}
//Last entry is relevant when a group ends at the end of the string.
// This behaviour leverages Python slicing automatically limiting the end index
lut[len] = len;
return lut;
}
/**
* Lookup table that maps the Python anchor arg to actual anchors.
*/
static const re2::RE2::Anchor anchorLUT[] = {
re2::RE2::UNANCHORED, re2::RE2::ANCHOR_BOTH, re2::RE2::ANCHOR_START};
/**
* Copy a StringPiece array to a C string list,
* each level of which is allocated using new[]
*/
char** copyGroups(const re2::StringPiece* groupsSrc, int numGroups) {
char** groups = new char*[numGroups];
for (int i = 0; i < numGroups; ++i) {
char* group = new char[groupsSrc[i].size() + 1];
group[groupsSrc[i].size()] = 0; //Insert C terminator
//Copy actual string
memcpy(group, groupsSrc[i].data(), groupsSrc[i].size());
groups[i] = group;
}
return groups;
}
extern "C" {
re2::RE2* RE2_new(const char* pattern, bool caseInsensitive) {
re2::RE2::Options options;
options.Copy(re2::RE2::Quiet);
if(caseInsensitive) {
options.set_case_sensitive(false);
}
options.set_max_mem(maxMemoryBudget);
re2::RE2* ptr = new re2::RE2(pattern, options);
return ptr;
}
int NumCapturingGroups(re2::RE2* re_obj) {
return re_obj->NumberOfCapturingGroups();
}
void FreeREMatchResult(REMatchResult mr) {
if(mr.ranges != NULL) {
delete[] mr.ranges;
mr.ranges = NULL;
}
}
void FreeREMultiMatchResult(REMultiMatchResult mr) {
if(mr.ranges != NULL) {
for (int i = 0; i < mr.numMatches; ++i) {
if(mr.ranges[i] != NULL) {
delete[] mr.ranges[i];
mr.ranges[i] = NULL;
}
}
delete[] mr.ranges;
mr.ranges = NULL;
}
}
REMultiMatchResult FindAllMatches(re2::RE2* re_obj, const char* dataArg, int anchorArg, int startpos) {
re2::StringPiece data(dataArg);
if(anchorArg >= 2) {
anchorArg = 0; //Should not happen
}
re2::RE2::Anchor anchor = anchorLUT[anchorArg];
//Build UTF8 lookup table for string
int* utf8LUT = buildUTF8IndexLUT(data.data(), data.size());
//Initialize return arg
REMultiMatchResult ret;
ret.numMatches = 0;
//Map anchor for easier Python iface
int numGroups = re_obj->NumberOfCapturingGroups();
ret.numElements = 1 + numGroups;
int pos = startpos;
int endidx = data.size();
//We don't know the size of this in advance, so we'll need to allocate now
re2::StringPiece* matchTmp = new re2::StringPiece[ret.numElements];
vector<Range*> allRanges;
/**
* Iterate over all non-overlapping (!) matches
*/
while(true) {
//Perform match
bool hasMatch = re_obj->Match(data, pos, endidx,
anchor, matchTmp, ret.numElements);
if(!hasMatch) {
break;
}
//Increment position pointer so we get the next hit
// We are returning non-overlapping matches, so this is OK
if(matchTmp[0].size() == 0) { //Zero-length match
pos++;
} else {
pos = matchTmp[0].data() - dataArg + matchTmp[0].size() ;
}
//Copy range
Range* rangeTmp = new Range[ret.numElements];
for (int i = 0; i < ret.numElements; ++i) {
if(matchTmp[i].data() == NULL) {
rangeTmp[i].start = -1;
rangeTmp[i].end = -1;
continue;
}
int rawStart = matchTmp[i].data() - dataArg;
rangeTmp[i].start = utf8LUT[rawStart];
rangeTmp[i].end = utf8LUT[rawStart + matchTmp[i].size()];
}
allRanges.push_back(rangeTmp);
}
//Compute final size
ret.numMatches = allRanges.size();
//Convert match vector to group vector (3D)
ret.ranges = new Range*[allRanges.size()];
for (size_t i = 0; i < allRanges.size(); ++i) {
//Copy ranges
ret.ranges[i] = new Range[ret.numElements];
memcpy(ret.ranges[i], allRanges[i], sizeof(Range*) * ret.numElements);
}
//Cleanup
delete[] utf8LUT;
delete[] matchTmp;
for (size_t i = 0; i < allRanges.size(); ++i) {
if(allRanges[i] != NULL) {
delete[] allRanges[i];
}
}
return ret;
}
REMatchResult FindSingleMatch(re2::RE2* re_obj, const char* dataArg, bool startAnchored, int startpos) {
re2::StringPiece data(dataArg);
REMatchResult ret;
ret.numGroups = re_obj->NumberOfCapturingGroups() + 1;
//Declare group target array
re2::StringPiece* groups = new re2::StringPiece[ret.numGroups]();
//Build UTF8 lookup table for string
int* utf8LUT = buildUTF8IndexLUT(data.data(), data.size());
//Perform either
re2::RE2::Anchor anchor = startAnchored ? re2::RE2::ANCHOR_START : re2::RE2::UNANCHORED;
ret.hasMatch = re_obj->Match(data, startpos, data.size(),
anchor, groups, ret.numGroups);
//Copy groups
if(ret.hasMatch) {
//Copy ranges
ret.ranges = new Range[ret.numGroups];
for (int i = 0; i < ret.numGroups; ++i) {
if(groups[i].data() == NULL) {
ret.ranges[i].start = -1;
ret.ranges[i].end = -1;
continue;
}
int rawStart = groups[i].data() - dataArg;
ret.ranges[i].start = utf8LUT[rawStart];
ret.ranges[i].end = utf8LUT[rawStart + groups[i].size()];
}
} else {
ret.ranges = NULL;
}
//Cleanup
delete[] groups;
delete[] utf8LUT;
//Return
return ret;
}
void RE2_delete(re2::RE2* re_obj) {
delete re_obj;
}
string* RE2_GlobalReplace(re2::RE2* re_obj, const char* str, const char* rewrite) {
string* ptr_s = new string(str);
re2::StringPiece sp(rewrite);
re2::RE2::GlobalReplace(ptr_s, *re_obj, sp);
return ptr_s;
}
const char* get_c_str(string* ptr_str) {
if(ptr_str == NULL) {
return NULL;
}
return ptr_str->c_str();
}
void RE2_delete_string_ptr(string* ptr) {
delete ptr;
}
const char* get_error_msg(re2::RE2* re_obj) {
if(!re_obj) {
return "";
}
string* ptr_s = (string*) &(re_obj->error());
return get_c_str(ptr_s);
}
bool ok(re2::RE2* re_obj) {
if(!re_obj) {
return false;
}
return re_obj->ok();
}
void RE2_SetMaxMemory(int maxmem) {
maxMemoryBudget = maxmem;
}
}