static EbnfExpression _ReadExpressions(EbnfParser parser)
{
EbnfExpression result = null;
throw new NotImplementedException();
return(result);
}
void _VisitFetchTerminals(EbnfExpression expr, HashSet <EbnfExpression> terms)
{
var l = expr as EbnfLiteralExpression;
if (null != l)
{
terms.Add(l);
return;
}
var r = expr as EbnfRegexExpression;
if (null != r)
{
terms.Add(r);
return;
}
var u = expr as EbnfUnaryExpression;
if (null != u)
{
_VisitFetchTerminals(u.Expression, terms);
return;
}
var b = expr as EbnfBinaryExpression;
if (null != b)
{
_VisitFetchTerminals(b.Left, terms);
_VisitFetchTerminals(b.Right, terms);
return;
}
}
public string GetIdForExpression(EbnfExpression expression)
{
foreach (var prod in Productions)
{
if (Equals(prod.Value.Expression, expression))
{
return(prod.Key);
}
}
return(null);
}
public EbnfOrExpression(EbnfExpression left, params EbnfExpression[] right)
{
if (null == right)
{
right = new EbnfExpression[] { null }
}
;
Left = left;
for (var i = 0; i < right.Length; ++i)
{
if (Right == null)
{
Right = right[i];
}
else
{
Right = new EbnfOrExpression(Right, right[i]);
}
}
}
public EbnfProduction(EbnfExpression expression)
{
Expression = expression;
}
public EbnfRepeatExpression(EbnfExpression expression)
{
Expression = expression;
}
public EbnfOptionalExpression(EbnfExpression expression)
{
Expression = expression;
}
static EbnfExpression _ParseExpression(EbnfDocument doc, ParseContext pc)
{
EbnfExpression current = null;
EbnfExpression e;
long position;
int line;
int column;
pc.TrySkipCCommentsAndWhiteSpace();
position = pc.Position; line = pc.Line; column = pc.Column;
while (-1 != pc.Current && ']' != pc.Current && ')' != pc.Current && '}' != pc.Current && ';' != pc.Current)
{
pc.TrySkipCCommentsAndWhiteSpace();
position = pc.Position; line = pc.Line; column = pc.Column;
switch (pc.Current)
{
case '|':
pc.Advance();
current = new EbnfOrExpression(current, _ParseExpression(doc, pc));
current.SetPositionInfo(line, column, position);
break;
case '(':
pc.Advance();
e = _ParseExpression(doc, pc);
current.SetPositionInfo(line, column, position);
pc.Expecting(')');
pc.Advance();
e.SetPositionInfo(line, column, position);
if (null == current)
{
current = e;
}
else
{
current = new EbnfConcatExpression(current, e);
}
break;
case '[':
pc.Advance();
e = new EbnfOptionalExpression(_ParseExpression(doc, pc));
e.SetPositionInfo(line, column, position);
pc.TrySkipCCommentsAndWhiteSpace();
pc.Expecting(']');
pc.Advance();
if (null == current)
{
current = e;
}
else
{
current = new EbnfConcatExpression(current, e);
}
break;
case '{':
pc.Advance();
e = new EbnfRepeatExpression(_ParseExpression(doc, pc));
e.SetPositionInfo(line, column, position);
pc.TrySkipCCommentsAndWhiteSpace();
pc.Expecting('}');
pc.Advance();
if (null == current)
{
current = e;
}
else
{
current = new EbnfConcatExpression(current, e);
}
break;
case '\"':
e = new EbnfLiteralExpression(pc.ParseJsonString());
if (null == current)
{
current = e;
}
else
{
current = new EbnfConcatExpression(current, e);
}
e.SetPositionInfo(line, column, position);
break;
case '\'':
pc.Advance();
pc.ClearCapture();
pc.TryReadUntil('\'', '\\', false);
pc.Expecting('\'');
pc.Advance();
e = new EbnfRegexExpression(pc.Capture);
if (null == current)
{
current = e;
}
else
{
current = new EbnfConcatExpression(current, e);
}
e.SetPositionInfo(line, column, position);
break;
case ';':
case ']':
case ')':
case '}':
return(current);
default:
e = new EbnfRefExpression(_ParseIdentifier(pc));
if (null == current)
{
current = e;
}
else
{
current = new EbnfConcatExpression(current, e);
}
e.SetPositionInfo(line, column, position);
break;
}
}
pc.TrySkipCCommentsAndWhiteSpace();
return(current);
}
void _ValidateExpression(EbnfExpression expr, IDictionary <string, int> refCounts, IList <EbnfMessage> messages)
{
var l = expr as EbnfLiteralExpression;
if (null != l)
{
var i = GetIdForExpression(l);
// don't count itself. only things just like itself
if (null != i && !ReferenceEquals(Productions[i].Expression, l))
{
refCounts[i] += 1;
}
}
var rx = expr as EbnfRegexExpression;
if (null != rx)
{
try
{
FA.Parse(rx.Value);
}
catch (ExpectingException)
{
messages.Add(
new EbnfMessage(
EbnfErrorLevel.Error, 12,
"Invalid regular expression",
expr.Line, expr.Column, expr.Position));
}
var i = GetIdForExpression(rx);
if (null != i && !ReferenceEquals(Productions[i].Expression, l))
{
refCounts[i] += 1;
}
}
var r = expr as EbnfRefExpression;
if (null != r)
{
int rc;
if (null == r.Symbol)
{
messages.Add(
new EbnfMessage(
EbnfErrorLevel.Error, 4,
"Null reference expression",
expr.Line, expr.Column, expr.Position));
return;
}
if (!refCounts.TryGetValue(r.Symbol, out rc))
{
messages.Add(
new EbnfMessage(
EbnfErrorLevel.Error, 1,
string.Concat(
"Reference to undefined symbol \"",
r.Symbol,
"\""),
expr.Line, expr.Column, expr.Position));
return;
}
refCounts[r.Symbol] = rc + 1;
return;
}
var b = expr as EbnfBinaryExpression;
if (null != b)
{
if (null == b.Left && null == b.Right)
{
messages.Add(
new EbnfMessage(
EbnfErrorLevel.Warning, 3,
"Nil expression",
expr.Line, expr.Column, expr.Position));
return;
}
_ValidateExpression(b.Left, refCounts, messages);
_ValidateExpression(b.Right, refCounts, messages);
return;
}
var u = expr as EbnfUnaryExpression;
if (null != u)
{
if (null == u.Expression)
{
messages.Add(
new EbnfMessage(
EbnfErrorLevel.Warning, 3,
"Nil expression",
expr.Line, expr.Column, expr.Position));
return;
}
_ValidateExpression(u.Expression, refCounts, messages);
}
}
