private Expression ParseSpecial (RegexOptions options) {
int p = ptr;
bool ecma = IsECMAScript (options);
Expression expr = null;
switch (pattern[ptr ++]) {
// categories
case 'd':
expr = new CharacterClass (ecma ? Category.EcmaDigit : Category.Digit, false);
break;
case 'w':
expr = new CharacterClass (ecma ? Category.EcmaWord : Category.Word, false);
break;
case 's':
expr = new CharacterClass (ecma ? Category.EcmaWhiteSpace : Category.WhiteSpace, false);
break;
case 'p':
// this is odd - ECMAScript isn't supposed to support Unicode,
// yet \p{..} compiles and runs under the MS implementation
// identically to canonical mode. That's why I'm ignoring the
// value of ecma here.
expr = new CharacterClass (ParseUnicodeCategory (), false);
break;
case 'D':
expr = new CharacterClass (ecma ? Category.EcmaDigit : Category.Digit, true);
break;
case 'W':
expr = new CharacterClass (ecma ? Category.EcmaWord : Category.Word, true);
break;
case 'S':
expr = new CharacterClass (ecma ? Category.EcmaWhiteSpace : Category.WhiteSpace, true);
break;
case 'P':
expr = new CharacterClass (ParseUnicodeCategory (), true);
break;
// positions
case 'A': expr = new PositionAssertion (Position.StartOfString); break;
case 'Z': expr = new PositionAssertion (Position.End); break;
case 'z': expr = new PositionAssertion (Position.EndOfString); break;
case 'G': expr = new PositionAssertion (Position.StartOfScan); break;
case 'b': expr = new PositionAssertion (Position.Boundary); break;
case 'B': expr = new PositionAssertion (Position.NonBoundary); break;
// references
case '1': case '2': case '3': case '4': case '5':
case '6': case '7': case '8': case '9': {
ptr --;
int n = ParseNumber (10, 1, 0);
if (n < 0) {
ptr = p;
return null;
}
// FIXME test if number is within number of assigned groups
// this may present a problem for right-to-left matching
Reference reference = new BackslashNumber (IsIgnoreCase (options), ecma);
refs.Add (reference, n.ToString ());
expr = reference;
break;
}
case 'k': {
char delim = pattern[ptr ++];
if (delim == '<')
delim = '>';
else if (delim != '\'')
throw NewParseException ("Malformed \\k<...> named backreference.");
string name = ParseName ();
if (name == null || pattern[ptr] != delim)
throw NewParseException ("Malformed \\k<...> named backreference.");
++ ptr;
Reference reference = new Reference (IsIgnoreCase (options));
refs.Add (reference, name);
expr = reference;
break;
}
default:
expr = null;
break;
}
if (expr == null)
ptr = p;
return expr;
}
// private methods
private void ParseGroup (Group group, RegexOptions options, Assertion assertion) {
bool is_top_level = group is RegularExpression;
Alternation alternation = null;
string literal = null;
Group current = new Group ();
Expression expr = null;
bool closed = false;
while (true) {
ConsumeWhitespace (IsIgnorePatternWhitespace (options));
if (ptr >= pattern.Length)
break;
// (1) Parse for Expressions
char ch = pattern[ptr ++];
switch (ch) {
case '^': {
Position pos =
IsMultiline (options) ? Position.StartOfLine : Position.Start;
expr = new PositionAssertion (pos);
break;
}
case '$': {
Position pos =
IsMultiline (options) ? Position.EndOfLine : Position.End;
expr = new PositionAssertion (pos);
break;
}
case '.': {
Category cat =
IsSingleline (options) ? Category.AnySingleline : Category.Any;
expr = new CharacterClass (cat, false);
break;
}
case '\\': {
int c = ParseEscape (false);
if (c >= 0)
ch = (char)c;
else {
expr = ParseSpecial (options);
if (expr == null)
ch = pattern[ptr ++]; // default escape
}
break;
}
case '[': {
expr = ParseCharacterClass (options);
break;
}
case '(': {
bool ignore = IsIgnoreCase (options);
expr = ParseGroupingConstruct (ref options);
if (expr == null) {
if (literal != null && IsIgnoreCase (options) != ignore) {
current.AppendExpression (new Literal (literal, IsIgnoreCase (options)));
literal = null;
}
continue;
}
break;
}
case ')': {
closed = true;
goto EndOfGroup;
}
case '|': {
if (literal != null) {
current.AppendExpression (new Literal (literal, IsIgnoreCase (options)));
literal = null;
}
if (assertion != null) {
if (assertion.TrueExpression == null)
assertion.TrueExpression = current;
else if (assertion.FalseExpression == null)
assertion.FalseExpression = current;
else
throw NewParseException ("Too many | in (?()|).");
}
else {
if (alternation == null)
alternation = new Alternation ();
alternation.AddAlternative (current);
}
current = new Group ();
continue;
}
case '*': case '+': case '?': {
throw NewParseException ("Bad quantifier.");
}
default:
break; // literal character
}
ConsumeWhitespace (IsIgnorePatternWhitespace (options));
// (2) Check for Repetitions
if (ptr < pattern.Length) {
char k = pattern[ptr];
int min = 0, max = 0;
bool lazy = false;
bool haveRep = false;
if (k == '?' || k == '*' || k == '+') {
++ ptr;
haveRep = true;
switch (k) {
case '?': min = 0; max = 1; break;
case '*': min = 0; max = 0x7fffffff; break;
case '+': min = 1; max = 0x7fffffff; break;
}
} else if (k == '{' && ptr + 1 < pattern.Length) {
int saved_ptr = ptr;
++ptr;
haveRep = ParseRepetitionBounds (out min, out max, options);
if (!haveRep)
ptr = saved_ptr;
}
if (haveRep) {
ConsumeWhitespace (IsIgnorePatternWhitespace (options));
if (ptr < pattern.Length && pattern[ptr] == '?') {
++ ptr;
lazy = true;
}
//It doesn't make sense to assert a given position more than once.
bool ignore_repetition = false;
if (expr is PositionAssertion) {
ignore_repetition = min > 0 && !lazy;
max = 1;
}
if (!ignore_repetition) {
Repetition repetition = new Repetition (min, max, lazy);
if (expr == null)
repetition.Expression = new Literal (ch.ToString (), IsIgnoreCase (options));
else
repetition.Expression = expr;
expr = repetition;
}
}
}
// (3) Append Expression and/or Literal
if (expr == null) {
if (literal == null)
literal = "";
literal += ch;
}
else {
if (literal != null) {
current.AppendExpression (new Literal (literal, IsIgnoreCase (options)));
literal = null;
}
current.AppendExpression (expr);
expr = null;
}
if (is_top_level && ptr >= pattern.Length)
goto EndOfGroup;
}
EndOfGroup:
if (is_top_level && closed)
throw NewParseException ("Too many )'s.");
if (!is_top_level && !closed)
throw NewParseException ("Not enough )'s.");
// clean up literals and alternations
if (literal != null)
current.AppendExpression (new Literal (literal, IsIgnoreCase (options)));
if (assertion != null) {
if (assertion.TrueExpression == null)
assertion.TrueExpression = current;
else
assertion.FalseExpression = current;
group.AppendExpression (assertion);
}
else if (alternation != null) {
alternation.AddAlternative (current);
group.AppendExpression (alternation);
}
else
group.AppendExpression (current);
}
private Expression ParseCharacterClass (RegexOptions options) {
bool negate = false;
if (pattern[ptr] == '^') {
negate = true;
++ ptr;
}
bool ecma = IsECMAScript (options);
CharacterClass cls = new CharacterClass (negate, IsIgnoreCase (options));
if (pattern[ptr] == ']') {
cls.AddCharacter (']');
++ ptr;
}
int c = -1;
int last = -1;
bool range = false;
bool closed = false;
while (ptr < pattern.Length) {
c = pattern[ptr ++];
if (c == ']') {
closed = true;
break;
}
if (c == '-' && last >= 0 && !range) {
range = true;
continue;
}
if (c == '\\') {
c = ParseEscape (true);
if (c >= 0)
goto char_recognized;
// didn't recognize escape
c = pattern [ptr ++];
switch (c) {
case 'b':
c = '\b';
goto char_recognized;
case 'd': case 'D':
cls.AddCategory (ecma ? Category.EcmaDigit : Category.Digit, c == 'D');
break;
case 'w': case 'W':
cls.AddCategory (ecma ? Category.EcmaWord : Category.Word, c == 'W');
break;
case 's': case 'S':
cls.AddCategory (ecma ? Category.EcmaWhiteSpace : Category.WhiteSpace, c == 'S');
break;
case 'p': case 'P':
cls.AddCategory (ParseUnicodeCategory (), c == 'P'); // ignore ecma
break;
default: // add escaped character
goto char_recognized;
}
// if the pattern looks like [a-\s] ...
if (range)
throw NewParseException ("character range cannot have category \\" + c);
last = -1;
continue;
}
char_recognized:
if (range) {
// if 'range' is true, we know that 'last >= 0'
if (c < last)
throw NewParseException ("[" + last + "-" + c + "] range in reverse order.");
cls.AddRange ((char)last, (char)c);
last = -1;
range = false;
continue;
}
cls.AddCharacter ((char)c);
last = c;
}
if (!closed)
throw NewParseException ("Unterminated [] set.");
if (range)
cls.AddCharacter ('-');
return cls;
}
private Expression ParseCharacterClass (RegexOptions options) {
bool negate, ecma;
if (pattern[ptr] == '^') {
negate = true;
++ ptr;
}
else
negate = false;
ecma = IsECMAScript (options);
CharacterClass cls = new CharacterClass (negate, IsIgnoreCase (options));
if (pattern[ptr] == ']') {
cls.AddCharacter (']');
++ ptr;
}
int c = -1;
int last = -1;
bool range = false;
bool closed = false;
while (ptr < pattern.Length) {
c = pattern[ptr ++];
if (c == ']') {
closed = true;
break;
}
if (c == '-') {
range = true;
continue;
}
if (c == '\\') {
c = ParseEscape ();
if (c < 0) {
// didn't recognize escape
c = pattern[ptr ++];
switch (c) {
case 'b': c = '\b'; break;
case 'd':
cls.AddCategory (ecma ? Category.EcmaDigit : Category.Digit, false);
last = -1;
continue;
case 'w':
cls.AddCategory (ecma ? Category.EcmaWord : Category.Word, false);
last = -1;
continue;
case 's':
cls.AddCategory (ecma ? Category.EcmaWhiteSpace : Category.WhiteSpace, false);
last = -1;
continue;
case 'p':
cls.AddCategory (ParseUnicodeCategory (), false); // ignore ecma
last = -1;
continue;
case 'D':
cls.AddCategory (ecma ? Category.EcmaDigit : Category.Digit, true);
last = -1;
continue;
case 'W':
cls.AddCategory (ecma ? Category.EcmaWord : Category.Word, true);
last = -1;
continue;
case 'S':
cls.AddCategory (ecma ? Category.EcmaWhiteSpace : Category.WhiteSpace, true);
last = -1;
continue;
case 'P':
cls.AddCategory (ParseUnicodeCategory (), true);
last = -1;
continue;
default: break; // add escaped character
}
}
}
if (range) {
if (c < last)
throw NewParseException ("[x-y] range in reverse order.");
if (last >=0 )
cls.AddRange ((char)last, (char)c);
else {
cls.AddCharacter ((char)c);
cls.AddCharacter ('-');
}
range = false;
last = -1;
}
else {
cls.AddCharacter ((char)c);
last = c;
}
}
if (!closed)
throw NewParseException ("Unterminated [] set.");
if (range)
cls.AddCharacter ('-');
return cls;
}