static IList <RegexCharsetEntry> _ParseRanges(ParseContext pc)
{
pc.EnsureStarted();
var result = new List <RegexCharsetEntry>();
RegexCharsetEntry next = null;
bool readDash = false;
while (-1 != pc.Current && ']' != pc.Current)
{
switch (pc.Current)
{
case '[': // char class
if (null != next)
{
result.Add(next);
if (readDash)
{
result.Add(new RegexCharsetCharEntry('-'));
}
result.Add(new RegexCharsetCharEntry('-'));
}
pc.Advance();
pc.Expecting(':');
pc.Advance();
var l = pc.CaptureBuffer.Length;
pc.TryReadUntil(':', false);
var n = pc.GetCapture(l);
pc.Advance();
pc.Expecting(']');
pc.Advance();
result.Add(new RegexCharsetClassEntry(n));
readDash = false;
next = null;
break;
case '\\':
pc.Advance();
pc.Expecting();
switch (pc.Current)
{
case 'h':
_ParseCharClassEscape(pc, "space", result, ref next, ref readDash);
break;
case 'd':
_ParseCharClassEscape(pc, "digit", result, ref next, ref readDash);
break;
case 'D':
_ParseCharClassEscape(pc, "^digit", result, ref next, ref readDash);
break;
case 'l':
_ParseCharClassEscape(pc, "lower", result, ref next, ref readDash);
break;
case 's':
_ParseCharClassEscape(pc, "space", result, ref next, ref readDash);
break;
case 'S':
_ParseCharClassEscape(pc, "^space", result, ref next, ref readDash);
break;
case 'u':
_ParseCharClassEscape(pc, "upper", result, ref next, ref readDash);
break;
case 'w':
_ParseCharClassEscape(pc, "word", result, ref next, ref readDash);
break;
case 'W':
_ParseCharClassEscape(pc, "^word", result, ref next, ref readDash);
break;
default:
var ch = (char)_ParseRangeEscapePart(pc);
if (null == next)
{
next = new RegexCharsetCharEntry(ch);
}
else if (readDash)
{
result.Add(new RegexCharsetRangeEntry(((RegexCharsetCharEntry)next).Value, ch));
next = null;
readDash = false;
}
else
{
result.Add(next);
next = new RegexCharsetCharEntry(ch);
}
break;
}
break;
case '-':
pc.Advance();
if (null == next)
{
next = new RegexCharsetCharEntry('-');
readDash = false;
}
else
{
if (readDash)
{
result.Add(next);
}
readDash = true;
}
break;
default:
if (null == next)
{
next = new RegexCharsetCharEntry((char)pc.Current);
}
else
{
if (readDash)
{
result.Add(new RegexCharsetRangeEntry(((RegexCharsetCharEntry)next).Value, (char)pc.Current));
next = null;
readDash = false;
}
else
{
result.Add(next);
next = new RegexCharsetCharEntry((char)pc.Current);
}
}
pc.Advance();
break;
}
}
if (null != next)
{
result.Add(next);
if (readDash)
{
next = new RegexCharsetCharEntry('-');
result.Add(next);
}
}
return(result);
}
static RegexExpression _ParseModifier(RegexExpression expr, ParseContext pc)
{
var line = pc.Line;
var column = pc.Column;
var position = pc.Position;
switch (pc.Current)
{
case '*':
expr = new RegexRepeatExpression(expr);
expr.SetLocation(line, column, position);
pc.Advance();
break;
case '+':
expr = new RegexRepeatExpression(expr, 1);
expr.SetLocation(line, column, position);
pc.Advance();
break;
case '?':
expr = new RegexOptionalExpression(expr);
expr.SetLocation(line, column, position);
pc.Advance();
break;
case '{':
pc.Advance();
pc.TrySkipWhiteSpace();
pc.Expecting('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', ',', '}');
var min = -1;
var max = -1;
if (',' != pc.Current && '}' != pc.Current)
{
var l = pc.CaptureBuffer.Length;
pc.TryReadDigits();
min = int.Parse(pc.GetCapture(l));
pc.TrySkipWhiteSpace();
}
if (',' == pc.Current)
{
pc.Advance();
pc.TrySkipWhiteSpace();
pc.Expecting('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '}');
if ('}' != pc.Current)
{
var l = pc.CaptureBuffer.Length;
pc.TryReadDigits();
max = int.Parse(pc.GetCapture(l));
pc.TrySkipWhiteSpace();
}
}
else
{
max = min;
}
pc.Expecting('}');
pc.Advance();
expr = new RegexRepeatExpression(expr, min, max);
expr.SetLocation(line, column, position);
break;
}
return(expr);
}
/// <summary>
/// Parses a regular expression from the specified <see cref="ParseContext"/>
/// </summary>
/// <param name="pc">The parse context to use</param>
/// <returns>A new abstract syntax tree representing the expression</returns>
public static RegexExpression Parse(ParseContext pc)
{
RegexExpression result = null, next = null;
int ich;
pc.EnsureStarted();
var line = pc.Line;
var column = pc.Column;
var position = pc.Position;
while (true)
{
switch (pc.Current)
{
case -1:
return(result);
case '.':
var nset = new RegexCharsetExpression(new RegexCharsetEntry[] { new RegexCharsetRangeEntry(char.MinValue, char.MaxValue) }, false);
nset.SetLocation(line, column, position);
if (null == result)
{
result = nset;
}
else
{
result = new RegexConcatExpression(result, nset);
result.SetLocation(line, column, position);
}
pc.Advance();
result = _ParseModifier(result, pc);
line = pc.Line;
column = pc.Column;
position = pc.Position;
break;
case '\\':
pc.Advance();
pc.Expecting();
switch (pc.Current)
{
case 'd':
next = new RegexCharsetExpression(new RegexCharsetEntry[] { new RegexCharsetClassEntry("digit") });
pc.Advance();
break;
case 'D':
next = new RegexCharsetExpression(new RegexCharsetEntry[] { new RegexCharsetClassEntry("digit") }, true);
pc.Advance();
break;
case 'h':
next = new RegexCharsetExpression(new RegexCharsetEntry[] { new RegexCharsetClassEntry("blank") });
pc.Advance();
break;
case 'l':
next = new RegexCharsetExpression(new RegexCharsetEntry[] { new RegexCharsetClassEntry("lower") });
pc.Advance();
break;
case 's':
next = new RegexCharsetExpression(new RegexCharsetEntry[] { new RegexCharsetClassEntry("space") });
pc.Advance();
break;
case 'S':
next = new RegexCharsetExpression(new RegexCharsetEntry[] { new RegexCharsetClassEntry("space") }, true);
pc.Advance();
break;
case 'u':
next = new RegexCharsetExpression(new RegexCharsetEntry[] { new RegexCharsetClassEntry("upper") });
pc.Advance();
break;
case 'w':
next = new RegexCharsetExpression(new RegexCharsetEntry[] { new RegexCharsetClassEntry("word") });
pc.Advance();
break;
case 'W':
next = new RegexCharsetExpression(new RegexCharsetEntry[] { new RegexCharsetClassEntry("word") }, true);
pc.Advance();
break;
default:
if (-1 != (ich = _ParseEscapePart(pc)))
{
next = new RegexLiteralExpression((char)ich);
}
else
{
pc.Expecting(); // throw an error
return(null); // doesn't execute
}
break;
}
next.SetLocation(line, column, position);
next = _ParseModifier(next, pc);
if (null != result)
{
result = new RegexConcatExpression(result, next);
result.SetLocation(line, column, position);
}
else
{
result = next;
}
line = pc.Line;
column = pc.Column;
position = pc.Position;
break;
case ')':
return(result);
case '(':
pc.Advance();
pc.Expecting();
next = Parse(pc);
pc.Expecting(')');
pc.Advance();
next = _ParseModifier(next, pc);
if (null == result)
{
result = next;
}
else
{
result = new RegexConcatExpression(result, next);
result.SetLocation(line, column, position);
}
line = pc.Line;
column = pc.Column;
position = pc.Position;
break;
case '|':
if (-1 != pc.Advance())
{
next = Parse(pc);
result = new RegexOrExpression(result, next);
result.SetLocation(line, column, position);
}
else
{
result = new RegexOrExpression(result, null);
result.SetLocation(line, column, position);
}
line = pc.Line;
column = pc.Column;
position = pc.Position;
break;
case '[':
pc.ClearCapture();
pc.Advance();
pc.Expecting();
bool not = false;
if ('^' == pc.Current)
{
not = true;
pc.Advance();
pc.Expecting();
}
var ranges = _ParseRanges(pc);
if (ranges.Count == 0)
{
System.Diagnostics.Debugger.Break();
}
pc.Expecting(']');
pc.Advance();
next = new RegexCharsetExpression(ranges, not);
next.SetLocation(line, column, position);
next = _ParseModifier(next, pc);
if (null == result)
{
result = next;
}
else
{
result = new RegexConcatExpression(result, next);
result.SetLocation(pc.Line, pc.Column, pc.Position);
}
line = pc.Line;
column = pc.Column;
position = pc.Position;
break;
default:
ich = pc.Current;
next = new RegexLiteralExpression((char)ich);
next.SetLocation(line, column, position);
pc.Advance();
next = _ParseModifier(next, pc);
if (null == result)
{
result = next;
}
else
{
result = new RegexConcatExpression(result, next);
result.SetLocation(line, column, position);
}
line = pc.Line;
column = pc.Column;
position = pc.Position;
break;
}
}
}
