/*
* Copyright (C) 2009 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef YarrParser_h
#define YarrParser_h
#include <runtime/UString.h>
#include "Yarr.h"
#include <wtf/ASCIICType.h>
#include <wtf/unicode/Unicode.h>
namespace JSC { namespace Yarr {
#define REGEXP_ERROR_PREFIX "Invalid regular expression: "
enum BuiltInCharacterClassID {
DigitClassID,
SpaceClassID,
WordClassID,
NewlineClassID,
};
// The Parser class should not be used directly - only via the Yarr::parse() method.
template<class Delegate>
class Parser {
private:
template<class FriendDelegate>
friend const char* parse(FriendDelegate& delegate, const UString& pattern, unsigned backReferenceLimit);
enum ErrorCode {
NoError,
PatternTooLarge,
QuantifierOutOfOrder,
QuantifierWithoutAtom,
MissingParentheses,
ParenthesesUnmatched,
ParenthesesTypeInvalid,
CharacterClassUnmatched,
CharacterClassOutOfOrder,
EscapeUnterminated,
NumberOfErrorCodes
};
/*
* CharacterClassParserDelegate:
*
* The class CharacterClassParserDelegate is used in the parsing of character
* classes. This class handles detection of character ranges. This class
* implements enough of the delegate interface such that it can be passed to
* parseEscape() as an EscapeDelegate. This allows parseEscape() to be reused
* to perform the parsing of escape characters in character sets.
*/
class CharacterClassParserDelegate {
public:
CharacterClassParserDelegate(Delegate& delegate, ErrorCode& err)
: m_delegate(delegate)
, m_err(err)
, m_state(Empty)
, m_character(0)
{
}
/*
* begin():
*
* Called at beginning of construction.
*/
void begin(bool invert)
{
m_delegate.atomCharacterClassBegin(invert);
}
/*
* atomPatternCharacter():
*
* This method is called either from parseCharacterClass() (for an unescaped
* character in a character class), or from parseEscape(). In the former case
* the value true will be passed for the argument 'hyphenIsRange', and in this
* mode we will allow a hypen to be treated as indicating a range (i.e. /[a-z]/
* is different to /[a\-z]/).
*/
void atomPatternCharacter(UChar ch, bool hyphenIsRange = false)
{
switch (m_state) {
case AfterCharacterClass:
// Following a builtin character class we need look out for a hyphen.
// We're looking for invalid ranges, such as /[\d-x]/ or /[\d-\d]/.
// If we see a hyphen following a charater class then unlike usual
// we'll report it to the delegate immediately, and put ourself into
// a poisoned state. Any following calls to add another character or
// character class will result in an error. (A hypen following a
// character-class is itself valid, but only at the end of a regex).
if (hyphenIsRange && ch == '-') {
m_delegate.atomCharacterClassAtom('-');
m_state = AfterCharacterClassHyphen;
return;
}
// Otherwise just fall through - cached character so treat this as Empty.
case Empty:
m_character = ch;
m_state = CachedCharacter;
return;
case CachedCharacter:
if (hyphenIsRange && ch == '-')
m_state = CachedCharacterHyphen;
else {
m_delegate.atomCharacterClassAtom(m_character);
m_character = ch;
}
return;
case CachedCharacterHyphen:
if (ch < m_character) {
m_err = CharacterClassOutOfOrder;
return;
}
m_delegate.atomCharacterClassRange(m_character, ch);
m_state = Empty;
return;
// See coment in atomBuiltInCharacterClass below.
// This too is technically an error, per ECMA-262, and again we
// we chose to allow this. Note a subtlely here that while we
// diverge from the spec's definition of CharacterRange we do
// remain in compliance with the grammar. For example, consider
// the expression /[\d-a-z]/. We comply with the grammar in
// this case by not allowing a-z to be matched as a range.
case AfterCharacterClassHyphen:
m_delegate.atomCharacterClassAtom(ch);
m_state = Empty;
return;
}
}
/*
* atomBuiltInCharacterClass():
*
* Adds a built-in character class, called by parseEscape().
*/
void atomBuiltInCharacterClass(BuiltInCharacterClassID classID, bool invert)
{
switch (m_state) {
case CachedCharacter:
// Flush the currently cached character, then fall through.
m_delegate.atomCharacterClassAtom(m_character);
case Empty:
case AfterCharacterClass:
m_state = AfterCharacterClass;
m_delegate.atomCharacterClassBuiltIn(classID, invert);
return;
// If we hit either of these cases, we have an invalid range that
// looks something like /[x-\d]/ or /[\d-\d]/.
// According to ECMA-262 this should be a syntax error, but
// empirical testing shows this to break teh webz. Instead we
// comply with to the ECMA-262 grammar, and assume the grammar to
// have matched the range correctly, but tweak our interpretation
// of CharacterRange. Effectively we implicitly handle the hyphen
// as if it were escaped, e.g. /[\w-_]/ is treated as /[\w\-_]/.
case CachedCharacterHyphen:
m_delegate.atomCharacterClassAtom(m_character);
m_delegate.atomCharacterClassAtom('-');
// fall through
case AfterCharacterClassHyphen:
m_delegate.atomCharacterClassBuiltIn(classID, invert);
m_state = Empty;
return;
}
}
/*
* end():
*
* Called at end of construction.
*/
void end()
{
if (m_state == CachedCharacter)
m_delegate.atomCharacterClassAtom(m_character);
else if (m_state == CachedCharacterHyphen) {
m_delegate.atomCharacterClassAtom(m_character);
m_delegate.atomCharacterClassAtom('-');
}
m_delegate.atomCharacterClassEnd();
}
// parseEscape() should never call these delegate methods when
// invoked with inCharacterClass set.
void assertionWordBoundary(bool) { ASSERT_NOT_REACHED(); }
void atomBackReference(unsigned) { ASSERT_NOT_REACHED(); }
private:
Delegate& m_delegate;
ErrorCode& m_err;
enum CharacterClassConstructionState {
Empty,
CachedCharacter,
CachedCharacterHyphen,
AfterCharacterClass,
AfterCharacterClassHyphen,
} m_state;
UChar m_character;
};
Parser(Delegate& delegate, const UString& pattern, unsigned backReferenceLimit)
: m_delegate(delegate)
, m_backReferenceLimit(backReferenceLimit)
, m_err(NoError)
, m_data(pattern.characters())
, m_size(pattern.length())
, m_index(0)
, m_parenthesesNestingDepth(0)
{
}
/*
* parseEscape():
*
* Helper for parseTokens() AND parseCharacterClass().
* Unlike the other parser methods, this function does not report tokens
* directly to the member delegate (m_delegate), instead tokens are
* emitted to the delegate provided as an argument. In the case of atom
* escapes, parseTokens() will call parseEscape() passing m_delegate as
* an argument, and as such the escape will be reported to the delegate.
*
* However this method may also be used by parseCharacterClass(), in which
* case a CharacterClassParserDelegate will be passed as the delegate that
* tokens should be added to. A boolean flag is also provided to indicate
* whether that an escape in a CharacterClass is being parsed (some parsing
* rules change in this context).
*
* The boolean value returned by this method indicates whether the token
* parsed was an atom (outside of a characted class \b and \B will be
* interpreted as assertions).
*/
template<bool inCharacterClass, class EscapeDelegate>
bool parseEscape(EscapeDelegate& delegate)
{
ASSERT(!m_err);
ASSERT(peek() == '\\');
consume();
if (atEndOfPattern()) {
m_err = EscapeUnterminated;
return false;
}
switch (peek()) {
// Assertions
case 'b':
consume();
if (inCharacterClass)
delegate.atomPatternCharacter('\b');
else {
delegate.assertionWordBoundary(false);
return false;
}
break;
case 'B':
consume();
if (inCharacterClass)
delegate.atomPatternCharacter('B');
else {
delegate.assertionWordBoundary(true);
return false;
}
break;
// CharacterClassEscape
case 'd':
consume();
delegate.atomBuiltInCharacterClass(DigitClassID, false);
break;
case 's':
consume();
delegate.atomBuiltInCharacterClass(SpaceClassID, false);
break;
case 'w':
consume();
delegate.atomBuiltInCharacterClass(WordClassID, false);
break;
case 'D':
consume();
delegate.atomBuiltInCharacterClass(DigitClassID, true);
break;
case 'S':
consume();
delegate.atomBuiltInCharacterClass(SpaceClassID, true);
break;
case 'W':
consume();
delegate.atomBuiltInCharacterClass(WordClassID, true);
break;
// DecimalEscape
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9': {
// To match Firefox, we parse an invalid backreference in the range [1-7] as an octal escape.
// First, try to parse this as backreference.
if (!inCharacterClass) {
ParseState state = saveState();
unsigned backReference = consumeNumber();
if (backReference <= m_backReferenceLimit) {
delegate.atomBackReference(backReference);
break;
}
restoreState(state);
}
// Not a backreference, and not octal.
if (peek() >= '8') {
delegate.atomPatternCharacter('\\');
break;
}
// Fall-through to handle this as an octal escape.
}
// Octal escape
case '0':
delegate.atomPatternCharacter(consumeOctal());
break;
// ControlEscape
case 'f':
consume();
delegate.atomPatternCharacter('\f');
break;
case 'n':
consume();
delegate.atomPatternCharacter('\n');
break;
case 'r':
consume();
delegate.atomPatternCharacter('\r');
break;
case 't':
consume();
delegate.atomPatternCharacter('\t');
break;
case 'v':
consume();
delegate.atomPatternCharacter('\v');
break;
// ControlLetter
case 'c': {
ParseState state = saveState();
consume();
if (!atEndOfPattern()) {
int control = consume();
// To match Firefox, inside a character class, we also accept numbers and '_' as control characters.
if (inCharacterClass ? WTF::isASCIIAlphanumeric(control) || (control == '_') : WTF::isASCIIAlpha(control)) {
delegate.atomPatternCharacter(control & 0x1f);
break;
}
}
restoreState(state);
delegate.atomPatternCharacter('\\');
break;
}
// HexEscape
case 'x': {
consume();
int x = tryConsumeHex(2);
if (x == -1)
delegate.atomPatternCharacter('x');
else
delegate.atomPatternCharacter(x);
break;
}
// UnicodeEscape
case 'u': {
consume();
int u = tryConsumeHex(4);
if (u == -1)
delegate.atomPatternCharacter('u');
else
delegate.atomPatternCharacter(u);
break;
}
// IdentityEscape
default:
delegate.atomPatternCharacter(consume());
}
return true;
}
/*
* parseAtomEscape(), parseCharacterClassEscape():
*
* These methods alias to parseEscape().
*/
bool parseAtomEscape()
{
return parseEscape<false>(m_delegate);
}
void parseCharacterClassEscape(CharacterClassParserDelegate& delegate)
{
parseEscape<true>(delegate);
}
/*
* parseCharacterClass():
*
* Helper for parseTokens(); calls dirctly and indirectly (via parseCharacterClassEscape)
* to an instance of CharacterClassParserDelegate, to describe the character class to the
* delegate.
*/
void parseCharacterClass()
{
ASSERT(!m_err);
ASSERT(peek() == '[');
consume();
CharacterClassParserDelegate characterClassConstructor(m_delegate, m_err);
characterClassConstructor.begin(tryConsume('^'));
while (!atEndOfPattern()) {
switch (peek()) {
case ']':
consume();
characterClassConstructor.end();
return;
case '\\':
parseCharacterClassEscape(characterClassConstructor);
break;
default:
characterClassConstructor.atomPatternCharacter(consume(), true);
}
if (m_err)
return;
}
m_err = CharacterClassUnmatched;
}
/*
* parseParenthesesBegin():
*
* Helper for parseTokens(); checks for parentheses types other than regular capturing subpatterns.
*/
void parseParenthesesBegin()
{
ASSERT(!m_err);
ASSERT(peek() == '(');
consume();
if (tryConsume('?')) {
if (atEndOfPattern()) {
m_err = ParenthesesTypeInvalid;
return;
}
switch (consume()) {
case ':':
m_delegate.atomParenthesesSubpatternBegin(false);
break;
case '=':
m_delegate.atomParentheticalAssertionBegin();
break;
case '!':
m_delegate.atomParentheticalAssertionBegin(true);
break;
default:
m_err = ParenthesesTypeInvalid;
}
} else
m_delegate.atomParenthesesSubpatternBegin();
++m_parenthesesNestingDepth;
}
/*
* parseParenthesesEnd():
*
* Helper for parseTokens(); checks for parse errors (due to unmatched parentheses).
*/
void parseParenthesesEnd()
{
ASSERT(!m_err);
ASSERT(peek() == ')');
consume();
if (m_parenthesesNestingDepth > 0)
m_delegate.atomParenthesesEnd();
else
m_err = ParenthesesUnmatched;
--m_parenthesesNestingDepth;
}
/*
* parseQuantifier():
*
* Helper for parseTokens(); checks for parse errors and non-greedy quantifiers.
*/
void parseQuantifier(bool lastTokenWasAnAtom, unsigned min, unsigned max)
{
ASSERT(!m_err);
ASSERT(min <= max);
if (lastTokenWasAnAtom)
m_delegate.quantifyAtom(min, max, !tryConsume('?'));
else
m_err = QuantifierWithoutAtom;
}
/*
* parseTokens():
*
* This method loops over the input pattern reporting tokens to the delegate.
* The method returns when a parse error is detected, or the end of the pattern
* is reached. One piece of state is tracked around the loop, which is whether
* the last token passed to the delegate was an atom (this is necessary to detect
* a parse error when a quantifier provided without an atom to quantify).
*/
void parseTokens()
{
bool lastTokenWasAnAtom = false;
while (!atEndOfPattern()) {
switch (peek()) {
case '|':
consume();
m_delegate.disjunction();
lastTokenWasAnAtom = false;
break;
case '(':
parseParenthesesBegin();
lastTokenWasAnAtom = false;
break;
case ')':
parseParenthesesEnd();
lastTokenWasAnAtom = true;
break;
case '^':
consume();
m_delegate.assertionBOL();
lastTokenWasAnAtom = false;
break;
case '$':
consume();
m_delegate.assertionEOL();
lastTokenWasAnAtom = false;
break;
case '.':
consume();
m_delegate.atomBuiltInCharacterClass(NewlineClassID, true);
lastTokenWasAnAtom = true;
break;
case '[':
parseCharacterClass();
lastTokenWasAnAtom = true;
break;
case '\\':
lastTokenWasAnAtom = parseAtomEscape();
break;
case '*':
consume();
parseQuantifier(lastTokenWasAnAtom, 0, quantifyInfinite);
lastTokenWasAnAtom = false;
break;
case '+':
consume();
parseQuantifier(lastTokenWasAnAtom, 1, quantifyInfinite);
lastTokenWasAnAtom = false;
break;
case '?':
consume();
parseQuantifier(lastTokenWasAnAtom, 0, 1);
lastTokenWasAnAtom = false;
break;
case '{': {
ParseState state = saveState();
consume();
if (peekIsDigit()) {
unsigned min = consumeNumber();
unsigned max = min;
if (tryConsume(','))
max = peekIsDigit() ? consumeNumber() : quantifyInfinite;
if (tryConsume('}')) {
if (min <= max)
parseQuantifier(lastTokenWasAnAtom, min, max);
else
m_err = QuantifierOutOfOrder;
lastTokenWasAnAtom = false;
break;
}
}
restoreState(state);
} // if we did not find a complete quantifer, fall through to the default case.
default:
m_delegate.atomPatternCharacter(consume());
lastTokenWasAnAtom = true;
}
if (m_err)
return;
}
if (m_parenthesesNestingDepth > 0)
m_err = MissingParentheses;
}
/*
* parse():
*
* This method calls parseTokens() to parse over the input and converts any
* error code to a const char* for a result.
*/
const char* parse()
{
if (m_size > MAX_PATTERN_SIZE)
m_err = PatternTooLarge;
else
parseTokens();
ASSERT(atEndOfPattern() || m_err);
// The order of this array must match the ErrorCode enum.
static const char* errorMessages[NumberOfErrorCodes] = {
0, // NoError
REGEXP_ERROR_PREFIX "regular expression too large",
REGEXP_ERROR_PREFIX "numbers out of order in {} quantifier",
REGEXP_ERROR_PREFIX "nothing to repeat",
REGEXP_ERROR_PREFIX "missing )",
REGEXP_ERROR_PREFIX "unmatched parentheses",
REGEXP_ERROR_PREFIX "unrecognized character after (?",
REGEXP_ERROR_PREFIX "missing terminating ] for character class",
REGEXP_ERROR_PREFIX "range out of order in character class",
REGEXP_ERROR_PREFIX "\\ at end of pattern"
};
return errorMessages[m_err];
}
// Misc helper functions:
typedef unsigned ParseState;
ParseState saveState()
{
return m_index;
}
void restoreState(ParseState state)
{
m_index = state;
}
bool atEndOfPattern()
{
ASSERT(m_index <= m_size);
return m_index == m_size;
}
int peek()
{
ASSERT(m_index < m_size);
return m_data[m_index];
}
bool peekIsDigit()
{
return !atEndOfPattern() && WTF::isASCIIDigit(peek());
}
unsigned peekDigit()
{
ASSERT(peekIsDigit());
return peek() - '0';
}
int consume()
{
ASSERT(m_index < m_size);
return m_data[m_index++];
}
unsigned consumeDigit()
{
ASSERT(peekIsDigit());
return consume() - '0';
}
unsigned consumeNumber()
{
unsigned n = consumeDigit();
// check for overflow.
for (unsigned newValue; peekIsDigit() && ((newValue = n * 10 + peekDigit()) >= n); ) {
n = newValue;
consume();
}
return n;
}
unsigned consumeOctal()
{
ASSERT(WTF::isASCIIOctalDigit(peek()));
unsigned n = consumeDigit();
while (n < 32 && !atEndOfPattern() && WTF::isASCIIOctalDigit(peek()))
n = n * 8 + consumeDigit();
return n;
}
bool tryConsume(UChar ch)
{
if (atEndOfPattern() || (m_data[m_index] != ch))
return false;
++m_index;
return true;
}
int tryConsumeHex(int count)
{
ParseState state = saveState();
int n = 0;
while (count--) {
if (atEndOfPattern() || !WTF::isASCIIHexDigit(peek())) {
restoreState(state);
return -1;
}
n = (n << 4) | WTF::toASCIIHexValue(consume());
}
return n;
}
Delegate& m_delegate;
unsigned m_backReferenceLimit;
ErrorCode m_err;
const UChar* m_data;
unsigned m_size;
unsigned m_index;
unsigned m_parenthesesNestingDepth;
// Derived by empirical testing of compile time in PCRE and WREC.
static const unsigned MAX_PATTERN_SIZE = 1024 * 1024;
};
/*
* Yarr::parse():
*
* The parse method is passed a pattern to be parsed and a delegate upon which
* callbacks will be made to record the parsed tokens forming the regex.
* Yarr::parse() returns null on success, or a const C string providing an error
* message where a parse error occurs.
*
* The Delegate must implement the following interface:
*
* void assertionBOL();
* void assertionEOL();
* void assertionWordBoundary(bool invert);
*
* void atomPatternCharacter(UChar ch);
* void atomBuiltInCharacterClass(BuiltInCharacterClassID classID, bool invert);
* void atomCharacterClassBegin(bool invert)
* void atomCharacterClassAtom(UChar ch)
* void atomCharacterClassRange(UChar begin, UChar end)
* void atomCharacterClassBuiltIn(BuiltInCharacterClassID classID, bool invert)
* void atomCharacterClassEnd()
* void atomParenthesesSubpatternBegin(bool capture = true);
* void atomParentheticalAssertionBegin(bool invert = false);
* void atomParenthesesEnd();
* void atomBackReference(unsigned subpatternId);
*
* void quantifyAtom(unsigned min, unsigned max, bool greedy);
*
* void disjunction();
*
* The regular expression is described by a sequence of assertion*() and atom*()
* callbacks to the delegate, describing the terms in the regular expression.
* Following an atom a quantifyAtom() call may occur to indicate that the previous
* atom should be quantified. In the case of atoms described across multiple
* calls (parentheses and character classes) the call to quantifyAtom() will come
* after the call to the atom*End() method, never after atom*Begin().
*
* Character classes may either be described by a single call to
* atomBuiltInCharacterClass(), or by a sequence of atomCharacterClass*() calls.
* In the latter case, ...Begin() will be called, followed by a sequence of
* calls to ...Atom(), ...Range(), and ...BuiltIn(), followed by a call to ...End().
*
* Sequences of atoms and assertions are broken into alternatives via calls to
* disjunction(). Assertions, atoms, and disjunctions emitted between calls to
* atomParenthesesBegin() and atomParenthesesEnd() form the body of a subpattern.
* atomParenthesesBegin() is passed a subpatternId. In the case of a regular
* capturing subpattern, this will be the subpatternId associated with these
* parentheses, and will also by definition be the lowest subpatternId of these
* parentheses and of any nested paretheses. The atomParenthesesEnd() method
* is passed the subpatternId of the last capturing subexpression nested within
* these paretheses. In the case of a capturing subpattern with no nested
* capturing subpatterns, the same subpatternId will be passed to the begin and
* end functions. In the case of non-capturing subpatterns the subpatternId
* passed to the begin method is also the first possible subpatternId that might
* be nested within these paretheses. If a set of non-capturing parentheses does
* not contain any capturing subpatterns, then the subpatternId passed to begin
* will be greater than the subpatternId passed to end.
*/
template<class Delegate>
const char* parse(Delegate& delegate, const UString& pattern, unsigned backReferenceLimit = quantifyInfinite)
{
return Parser<Delegate>(delegate, pattern, backReferenceLimit).parse();
}
} } // namespace JSC::Yarr
#endif // YarrParser_h