scuffed-code/icu4c/source/i18n/rematch.cpp
2002-11-07 02:34:46 +00:00

909 lines
28 KiB
C++

//
// file: rematch.cpp
//
// Contains the implementation of class RegexMatcher,
// which is one of the main API classes for the ICU regular expression package.
//
/*
**********************************************************************
* Copyright (C) 2002 International Business Machines Corporation *
* and others. All rights reserved. *
**********************************************************************
*/
#include "unicode/utypes.h"
#if !UCONFIG_NO_REGULAR_EXPRESSIONS
#include "unicode/regex.h"
#include "unicode/uniset.h"
#include "unicode/uchar.h"
#include "uassert.h"
#include "uvector.h"
#include "regeximp.h"
#include "stdio.h"
U_NAMESPACE_BEGIN
//-----------------------------------------------------------------------------
//
// Constructor and Destructor
//
//-----------------------------------------------------------------------------
RegexMatcher::RegexMatcher(const RegexPattern *pat) {
fPattern = pat;
fInput = NULL;
fInputLength = 0;
UErrorCode status = U_ZERO_ERROR;
fBackTrackStack = new UStack(status); // TODO: do something with status.
fCaptureStarts = new UVector(status);
fCaptureEnds = new UVector(status);
int i;
for (i=0; i<=fPattern->fNumCaptureGroups; i++) {
fCaptureStarts->addElement(-1, status);
fCaptureEnds ->addElement(-1, status);
}
reset();
}
RegexMatcher::RegexMatcher(const RegexMatcher &other) {
U_ASSERT(FALSE);
}
RegexMatcher::~RegexMatcher() {
delete fBackTrackStack;
delete fCaptureStarts;
delete fCaptureEnds;
}
static const UChar BACKSLASH = 0x5c;
static const UChar DOLLARSIGN = 0x24;
//--------------------------------------------------------------------------------
//
// appendReplacement
//
//--------------------------------------------------------------------------------
RegexMatcher &RegexMatcher::appendReplacement(UnicodeString &dest,
const UnicodeString &replacement,
UErrorCode &status) {
if (U_FAILURE(status)) {
return *this;
}
if (fMatch == FALSE) {
status = U_REGEX_INVALID_STATE;
return *this;
}
// Copy input string from the end of previous match to start of current match
int32_t len = fMatchStart-fLastMatchEnd;
if (len > 0) {
dest.append(*fInput, fLastMatchEnd, len);
}
// scan the replacement text, looking for substitutions ($n) and \escapes.
int32_t replLen = replacement.length();
int32_t replIdx;
for (replIdx = 0; replIdx<replLen; replIdx++) {
UChar c = replacement.charAt(replIdx);
if (c == BACKSLASH) {
// Backslash Escape. Copy the following char out without further checks.
replIdx++;
if (replIdx >= replLen) {
break;
}
c = replacement.charAt(replIdx);
dest.append(c);
continue;
}
if (c != DOLLARSIGN) {
// Normal char, not a $. Copy it out without further checks.
dest.append(c);
continue;
}
// We've got a $. Pick up a capture group number if one follows.
// Consume at most the number of digits necessary for the largest capture
// number that is valid for this pattern.
if (++replIdx >= replLen) {
// $ was at the end of the replacement string. Dump it out and be done.
dest.append(c);
break;
}
int32_t numDigits = 0;
int32_t groupNum = 0;
for (;;) {
c = replacement.charAt(replIdx);
if (u_isdigit(c) == FALSE) {
break;
}
groupNum=groupNum*10 + u_charDigitValue(c);
numDigits++;
if (++replIdx >= replLen) {
break;
}
if (numDigits >= fPattern->fMaxCaptureDigits) {
break;
}
}
// We've scanned one char ahead in the pattern. Back up so the
// next iteration of the loop picks the char again.
--replIdx;
if (numDigits == 0) {
// The $ didn't introduce a group number at all.
// Treat it as just part of the substitution text.
dest.append(DOLLARSIGN);
continue;
}
// Finally, append the capture group data to the destination.
dest.append(group(groupNum, status));
if (U_FAILURE(status)) {
// Can fail if group number is out of range.
return *this;
}
}
return *this;
}
//--------------------------------------------------------------------------------
//
// appendTail Intended to be used in conjunction with appendReplacement()
// To the destination string, append everything following
// the last match position from the input string.
//
//--------------------------------------------------------------------------------
UnicodeString &RegexMatcher::appendTail(UnicodeString &dest) {
int32_t len = fInputLength-fMatchEnd;
if (len > 0) {
dest.append(*fInput, fMatchEnd, len);
}
return dest;
}
//--------------------------------------------------------------------------------
//
// end
//
//--------------------------------------------------------------------------------
int32_t RegexMatcher::end(UErrorCode &err) const {
return end(0, err);
}
int32_t RegexMatcher::end(int group, UErrorCode &err) const {
if (U_FAILURE(err)) {
return -1;
}
if (fMatch == FALSE) {
err = U_REGEX_INVALID_STATE;
return -1;
}
if (group < 0 || group > fPattern->fNumCaptureGroups) {
err = U_INDEX_OUTOFBOUNDS_ERROR;
return -1;
}
int32_t e = -1;
if (group == 0) {
e = fMatchEnd;
} else {
// Note: When the match engine backs out of a capture group, it sets the
// group's start position to -1. The end position is left with junk.
// So, before returning an end position, we must first check that
// the start position indicates that the group matched something.
int32_t s = fCaptureStarts->elementAti(group);
if (s != -1) {
e = fCaptureEnds->elementAti(group);
}
}
return e;
}
//--------------------------------------------------------------------------------
//
// find()
//
//--------------------------------------------------------------------------------
UBool RegexMatcher::find() {
// Start at the position of the last match end. (Will be zero if the
// matcher has been reset.
UErrorCode status = U_ZERO_ERROR;
int32_t startPos;
for (startPos=fMatchEnd; startPos < fInputLength; startPos++) {
MatchAt(startPos, status);
if (U_FAILURE(status)) {
return FALSE;
}
if (fMatch) {
return TRUE;
}
}
return FALSE;
}
UBool RegexMatcher::find(int32_t start, UErrorCode &status) {
if (U_FAILURE(status)) {
return FALSE;
}
if (start < 0 || start >= fInputLength) {
status = U_INDEX_OUTOFBOUNDS_ERROR;
return FALSE;
}
this->reset();
// TODO: optimize a search for the first char of a possible match.
// TODO: optimize the search for a leading literal string.
// TODO: optimize based on the minimum length of a possible match
int32_t startPos;
for (startPos=start; startPos < fInputLength; startPos++) {
MatchAt(startPos, status);
if (U_FAILURE(status)) {
return FALSE;
}
if (fMatch) {
return TRUE;
}
}
return FALSE;
}
//--------------------------------------------------------------------------------
//
// group()
//
//--------------------------------------------------------------------------------
UnicodeString RegexMatcher::group(UErrorCode &status) const {
return group(0, status);
}
UnicodeString RegexMatcher::group(int32_t group, UErrorCode &status) const {
int32_t s = start(group, status);
int32_t e = end(group, status);
if (U_FAILURE(status)) {
return UnicodeString();
}
if (s < 0 || s >= e) {
// Possible cases when a capture group didn't match
// TODO: firgure out what non-matching capture groups really are supposed to do.
return UnicodeString();
}
return UnicodeString(*fInput, s, e-s);
}
int32_t RegexMatcher::groupCount() const {
return fPattern->fNumCaptureGroups;
}
const UnicodeString &RegexMatcher::input() const {
return *fInput;
}
UBool RegexMatcher::lookingAt(UErrorCode &status) {
if (U_FAILURE(status)) {
return FALSE;
}
reset();
MatchAt(0, status);
return fMatch;
}
UBool RegexMatcher::matches(UErrorCode &status) {
if (U_FAILURE(status)) {
return FALSE;
}
reset();
MatchAt(0, status);
UBool success = (fMatch && fMatchEnd==fInputLength);
return success;
}
const RegexPattern &RegexMatcher::pattern() const {
return *fPattern;
}
//--------------------------------------------------------------------------------
//
// replaceAll
//
//--------------------------------------------------------------------------------
UnicodeString RegexMatcher::replaceAll(const UnicodeString &replacement, UErrorCode &status) {
if (U_FAILURE(status)) {
return *fInput;
}
UnicodeString destString;
for (reset(); find(); ) {
appendReplacement(destString, replacement, status);
}
appendTail(destString);
return destString;
}
//--------------------------------------------------------------------------------
//
// replaceFirst
//
//--------------------------------------------------------------------------------
UnicodeString RegexMatcher::replaceFirst(const UnicodeString &replacement, UErrorCode &status) {
if (U_FAILURE(status)) {
return *fInput;
}
reset();
if (!find()) {
return *fInput;
}
UnicodeString destString;
appendReplacement(destString, replacement, status);
appendTail(destString);
return destString;
}
//--------------------------------------------------------------------------------
//
// reset
//
//--------------------------------------------------------------------------------
RegexMatcher &RegexMatcher::reset() {
fMatchStart = 0;
fMatchEnd = 0;
fLastMatchEnd = 0;
fMatch = FALSE;
int i;
for (i=0; i<=fPattern->fNumCaptureGroups; i++) {
fCaptureStarts->setElementAt(-1, i);
}
return *this;
}
RegexMatcher &RegexMatcher::reset(const UnicodeString &input) {
fInput = &input;
fInputLength = input.length();
reset();
return *this;
}
int32_t RegexMatcher::start(UErrorCode &err) const {
return start(0, err);
}
int32_t RegexMatcher::start(int group, UErrorCode &err) const {
if (U_FAILURE(err)) {
return -1;
}
if (fMatch == FALSE) {
err = U_REGEX_INVALID_STATE;
return -1;
}
if (group < 0 || group > fPattern->fNumCaptureGroups) {
err = U_INDEX_OUTOFBOUNDS_ERROR;
return -1;
}
int32_t s;
if (group == 0) {
s = fMatchStart;
} else {
s = fCaptureStarts->elementAti(group);
// TODO: what to do if no match on this specific group?
}
return s;
}
//--------------------------------------------------------------------------------
//
// isWordBoundary
// in perl, "xab..cd..", \b is true at positions 0,3,5,7
// For us,
// If the current char is a combining mark,
// \b is FALSE.
// Else Scan backwards to the first non-combining char.
// We are at a boundary if the this char and the original chars are
// opposite in membership in \w set
//
//--------------------------------------------------------------------------------
UBool RegexMatcher::isWordBoundary(int32_t pos) {
UBool isBoundary = FALSE;
if (pos >= fInputLength) {
// off end of string. Not a boundary.
return FALSE;
}
// Determine whether char c at Pos is a member of the word set of chars.
UChar32 c = fInput->char32At(pos);
int8_t ctype = u_charType(c);
if (ctype==U_NON_SPACING_MARK || ctype==U_ENCLOSING_MARK) {
// Current char is a combining one. Not a boundary.
return FALSE;
}
UBool cIsWord = fPattern->fStaticSets[URX_ISWORD_SET]->contains(c);
// Back up until we come to a non-combining char, determine whether
// that char is a word char.
UBool prevCIsWord = FALSE;
int32_t prevPos = pos;
for (;;) {
if (prevPos == 0) {
break;
}
prevPos = fInput->moveIndex32(prevPos, -1);
UChar32 prevChar = fInput->char32At(prevPos);
int8_t prevCType = u_charType(prevChar);
if (!(prevCType==U_NON_SPACING_MARK || prevCType==U_ENCLOSING_MARK)) {
prevCIsWord = fPattern->fStaticSets[URX_ISWORD_SET]->contains(prevChar);
break;
}
}
isBoundary = cIsWord ^ prevCIsWord;
return isBoundary;
}
//--------------------------------------------------------------------------------
//
// backTrack Within the match engine, this function is called when
// a local match failure occurs, and the match needs to back
// track and proceed down another path.
//
// Note: Inline function. Keep its body above MatchAt().
//
//--------------------------------------------------------------------------------
void RegexMatcher::backTrack(int32_t &inputIdx, int32_t &patIdx) {
inputIdx = fBackTrackStack->popi();
patIdx = fBackTrackStack->popi();
int i;
for (i=1; i<=fPattern->fNumCaptureGroups; i++) {
int32_t cge = fBackTrackStack->popi();
fCaptureEnds->setElementAt(cge, i);
int32_t cgs = fBackTrackStack->popi();
fCaptureStarts->setElementAt(cgs, i);
}
}
//--------------------------------------------------------------------------------
//
// MatchAt This is the actual matching engine.
//
//--------------------------------------------------------------------------------
void RegexMatcher::MatchAt(int32_t startIdx, UErrorCode &status) {
int32_t inputIdx = startIdx; // Current position in the input string.
int32_t patIdx = 0; // Current position in the compiled pattern.
UBool isMatch = FALSE; // True if the we have a match.
int32_t op; // Operation from the compiled pattern, split into
int32_t opType; // the opcode
int32_t opValue; // and the operand value.
if (U_FAILURE(status)) {
return;
}
// Clear out capture results from any previous match.
// Needed to clear capture groups in patterns with | operations that may not match at all,
// although the pattern as a whole does match.
int i;
for (i=0; i<=fPattern->fNumCaptureGroups; i++) {
fCaptureStarts->setElementAt(-1, i);
}
// Cache frequently referenced items from the compiled pattern
// in local variables.
//
UVector *pat = fPattern->fCompiledPat;
const UnicodeString *litText = &fPattern->fLiteralText;
UVector *sets = fPattern->fSets;
int32_t inputLen = fInput->length();
//
// Main loop for interpreting the compiled pattern.
// One iteration of the loop per pattern operation performed.
//
for (;;) {
op = pat->elementAti(patIdx);
opType = URX_TYPE(op);
opValue = URX_VAL(op);
// printf("%d %d \"%c\"\n", patIdx, inputIdx, fInput->char32At(inputIdx));
patIdx++;
switch (opType) {
case URX_NOP:
break;
case URX_ONECHAR:
{
UChar32 inputChar = fInput->char32At(inputIdx);
if (inputChar == opValue) {
// TODO: handle the bogus 0xffff return from char32At for index out of range.
inputIdx = fInput->moveIndex32(inputIdx, 1);
} else {
// No match. Back up matching to a saved state
backTrack(inputIdx, patIdx);
}
break;
}
case URX_STRING:
{
int32_t stringStartIdx, stringLen;
stringStartIdx = opValue;
op = pat->elementAti(patIdx);
patIdx++;
opType = URX_TYPE(op);
opValue = URX_VAL(op);
U_ASSERT(opType == URX_STRING_LEN);
stringLen = opValue;
if (fInput->compareBetween(inputIdx,
inputIdx+stringLen,
*litText,
stringStartIdx,
stringStartIdx+stringLen) == 0)
{
inputIdx += stringLen;
} else {
// No match. Back up matching to a saved state
backTrack(inputIdx, patIdx);
}
}
break;
case URX_STATE_SAVE:
// Save the state of all capture groups, the pattern continuation
// postion and the input position.
{
int i;
for (i=fPattern->fNumCaptureGroups; i>0; i--) {
fBackTrackStack->push(fCaptureStarts->elementAt(i), status);
fBackTrackStack->push(fCaptureEnds->elementAt(i), status);
}
fBackTrackStack->push(opValue, status); // pattern continuation position
fBackTrackStack->push(inputIdx, status); // current input position
}
break;
case URX_END:
// The match loop will exit via this path on a successful match,
// when we reach the end of the pattern.
isMatch = TRUE;
goto breakFromLoop;
case URX_START_CAPTURE:
U_ASSERT(opValue > 0 && opValue <= fPattern->fNumCaptureGroups);
fCaptureStarts->setElementAt(inputIdx, opValue);
fCaptureEnds ->setElementAt((int32_t)0, opValue);
break;
case URX_END_CAPTURE:
U_ASSERT(opValue > 0 && opValue <= fPattern->fNumCaptureGroups);
fCaptureEnds->setElementAt(inputIdx, opValue);
break;
case URX_DOLLAR: // $, test for End of line
// or for position before new line at end of input
if (inputIdx < inputLen-2) {
// We are no where near the end of input. Fail.
backTrack(inputIdx, patIdx);
break;
}
if (inputIdx >= inputLen) {
// We really are at the end of input. Success.
break;
}
// If we are positioned just before a new-line that is located at the
// end of input, succeed.
if (inputIdx == inputLen-1) {
UChar32 c = fInput->char32At(inputIdx);
if (c == 0x0a || c==0x0d || c==0x0c || c==0x85 ||c==0x2028 || c==0x2029) {
break; // At new-line at end of input. Success
}
}
if (inputIdx == inputLen-2) {
if (fInput->char32At(inputIdx) == 0x0d && fInput->char32At(inputIdx+1) == 0x0a) {
break; // At CR/LF at end of input. Success
}
}
backTrack(inputIdx, patIdx);
// TODO: support for multi-line mode.
break;
case URX_CARET: // ^, test for start of line
if (inputIdx != 0) {
backTrack(inputIdx, patIdx);
} // TODO: support for multi-line mode.
break;
case URX_BACKSLASH_A: // Test for start of input
if (inputIdx != 0) {
backTrack(inputIdx, patIdx);
}
break;
case URX_BACKSLASH_B: // Test for word boundaries
{
UBool success = isWordBoundary(inputIdx);
success ^= (opValue != 0); // flip sense for \B
if (!success) {
backTrack(inputIdx, patIdx);
}
}
break;
case URX_BACKSLASH_D:
{
if (inputIdx >= fInputLength) {
backTrack(inputIdx, patIdx);
break;
}
UChar32 c = fInput->char32At(inputIdx);
int8_t ctype = u_charType(c);
UBool success = (ctype == U_DECIMAL_DIGIT_NUMBER);
success ^= (opValue != 0);
if (success) {
inputIdx = fInput->moveIndex32(inputIdx, 1);
} else {
backTrack(inputIdx, patIdx);
}
}
break;
case URX_BACKSLASH_G: // Test for position at end of previous match
if (!((fMatch && inputIdx==fMatchEnd) || fMatch==FALSE && inputIdx==0)) {
backTrack(inputIdx, patIdx);
}
break;
case URX_BACKSLASH_X: // Match combining character sequence
{
// Fail if at end of input
if (inputIdx >= fInputLength) {
backTrack(inputIdx, patIdx);
break;
}
// Always consume one char
UChar32 c = fInput->char32At(inputIdx);
inputIdx = fInput->moveIndex32(inputIdx, 1);
// Consume CR/LF as a pair
if (c == 0x0d) {
UChar32 c = fInput->char32At(inputIdx);
if (c == 0x0a) {
inputIdx = fInput->moveIndex32(inputIdx, 1);
break;
}
}
// Consume any combining marks following a non-control char
int8_t ctype = u_charType(c);
if (ctype != U_CONTROL_CHAR) {
for(;;) {
c = fInput->char32At(inputIdx);
ctype = u_charType(c);
// TODO: make a set and add the "other grapheme extend" chars
// to the list of stuff to be skipped over.
if (!(ctype == U_NON_SPACING_MARK || ctype == U_ENCLOSING_MARK)) {
break;
}
inputIdx = fInput->moveIndex32(inputIdx, 1);
if (inputIdx >= fInputLength) {
break;
}
}
}
}
break;
case URX_BACKSLASH_Z: // Test for end of line
if (inputIdx < inputLen) {
backTrack(inputIdx, patIdx);
}
break;
case URX_STATIC_SETREF:
{
// Test input character against one of the predefined sets
// (Word Characters, for example)
// The high bit of the op value is a flag for the match polarity.
// 0: success if input char is in set.
// 1: success if input char is not in set.
UBool success = ((opValue & URX_NEG_SET) == URX_NEG_SET);
opValue &= ~URX_NEG_SET;
if (inputIdx < fInputLength) {
// There is input left. Pick up one char and test it for set membership.
UChar32 c = fInput->char32At(inputIdx);
U_ASSERT(opValue > 0 && opValue < URX_LAST_SET);
const UnicodeSet *s = fPattern->fStaticSets[opValue];
if (s->contains(c)) {
success = !success;
}
}
if (success) {
inputIdx = fInput->moveIndex32(inputIdx, 1);
} else {
backTrack(inputIdx, patIdx);
}
}
break;
case URX_SETREF:
if (inputIdx < fInputLength) {
// There is input left. Pick up one char and test it for set membership.
UChar32 c = fInput->char32At(inputIdx);
U_ASSERT(opValue > 0 && opValue < sets->size());
UnicodeSet *s = (UnicodeSet *)sets->elementAt(opValue);
if (s->contains(c)) {
// The character is in the set. A Match.
inputIdx = fInput->moveIndex32(inputIdx, 1);
break;
}
}
// Either at end of input, or the character wasn't in the set.
// Either way, we need to back track out.
backTrack(inputIdx, patIdx);
break;
case URX_DOTANY:
{
// . matches anything
if (inputIdx >= fInputLength) {
// At end of input. Match failed. Backtrack out.
backTrack(inputIdx, patIdx);
break;
}
// There is input left. Advance over one char, unless we've hit end-of-line
UChar32 c = fInput->char32At(inputIdx);
inputIdx = fInput->moveIndex32(inputIdx, 1);
if (c == 0x0a || c==0x0d || c==0x0c || c==0x85 ||c==0x2028 || c==0x2029) {
// End of line in normal mode. . does not match.
backTrack(inputIdx, patIdx);
break;
}
}
break;
case URX_DOTANY_ALL:
{
// ., in dot-matches-all (including new lines) mode
// . matches anything
if (inputIdx >= fInputLength) {
// At end of input. Match failed. Backtrack out.
backTrack(inputIdx, patIdx);
break;
}
// There is input left. Advance over one char, unless we've hit end-of-line
UChar32 c = fInput->char32At(inputIdx);
inputIdx = fInput->moveIndex32(inputIdx, 1);
if (c == 0x0a || c==0x0d || c==0x0c || c==0x85 ||c==0x2028 || c==0x2029) {
// In the case of a CR/LF, we need to advance over both.
UChar32 nextc = fInput->char32At(inputIdx);
if (c == 0x0d && nextc == 0x0a) {
inputIdx = fInput->moveIndex32(inputIdx, 1);
}
}
}
break;
case URX_JMP:
patIdx = opValue;
break;
case URX_FAIL:
isMatch = FALSE;
goto breakFromLoop;
default:
// Trouble. The compiled pattern contains an entry with an
// unrecognized type tag.
U_ASSERT(FALSE);
}
if (U_FAILURE(status)) {
break;
}
}
breakFromLoop:
fMatch = isMatch;
if (isMatch) {
fLastMatchEnd = fMatchEnd;
fMatchStart = startIdx;
fMatchEnd = inputIdx;
}
return;
}
const char RegexMatcher::fgClassID = 0;
U_NAMESPACE_END
#endif // !UCONFIG_NO_REGULAR_EXPRESSIONS