public override CharFA ToFA(EbnfDocument parent, Cfg cfg)
{
if (null == Expression)
{
return(null);
}
return(CharFA.Optional(Expression.ToFA(parent, cfg), (null == parent) ? "" : parent.GetContainingIdForExpression(this)));
}
public override CharFA ToFA(EbnfDocument parent, Cfg cfg)
{
if (null == Expression)
{
return(null);
}
var result = CharFA.Repeat(Expression.ToFA(parent, cfg), (null == parent) ? "" : parent.GetContainingIdForExpression(this));
if (IsOptional)
{
result = CharFA.Optional(result);
}
return(result);
}
public override CharFA ToFA(EbnfDocument parent, Cfg cfg)
{
string sym = "";
if (null != parent)
{
sym = parent.GetContainingIdForExpression(this);
}
if (null == Right)
{
if (null == Left)
{
return(null);
}
return(CharFA.Optional(Left.ToFA(parent, cfg), sym));
}
else if (null == Left)
{
return(CharFA.Optional(Right.ToFA(parent, cfg), sym));
}
return(CharFA.Or(new CharFA[] { Left.ToFA(parent, cfg), Right.ToFA(parent, cfg) }, sym));
}
static void _BuildArticleImages()
{
// this generates the figures used in the code project article
// at https://www.codeproject.com/Articles/5251476/How-to-Build-a-Regex-Engine-in-Csharp
var litA = CharFA <string> .Literal("ABC", "Accept");
litA.RenderToFile(@"..\..\..\literal.jpg");
var litAa = CharFA <string> .CaseInsensitive(litA, "Accept");
litAa.RenderToFile(@"..\..\..\literal_ci.jpg");
var opt = CharFA <string> .Optional(litA, "Accept");
opt.RenderToFile(@"..\..\..\optional.jpg");
var litB = CharFA <string> .Literal("DEF");
var or = CharFA <string> .Or(new CharFA <string>[] { litA, litB }, "Accept");
or.RenderToFile(@"..\..\..\or.jpg");
var set = CharFA <string> .Set("ABC", "Accept");
set.RenderToFile(@"..\..\..\set.jpg");
var loop = CharFA <string> .Repeat(litA, 1, -1, "Accept");
loop.RenderToFile(@"..\..\..\repeat.jpg");
var concat = CharFA <string> .Concat(new CharFA <string>[] { litA, litB }, "Accept");
concat.RenderToFile(@"..\..\..\concat.jpg");
var foobar = CharFA <string> .Or(new CharFA <string>[] { CharFA <string> .Literal("foo"), CharFA <string> .Literal("bar") }, "Accept");
foobar.RenderToFile(@"..\..\..\foobar_nfa.jpg");
var rfoobar = foobar.Reduce();
rfoobar.RenderToFile(@"..\..\..\foobar.jpg");
var lfoobar = CharFA <string> .Repeat(foobar, 1, -1, "Accept");
lfoobar.RenderToFile(@"..\..\..\foobar_loop_nfa.jpg");
var rlfoobar = lfoobar.Reduce();
rlfoobar.RenderToFile(@"..\..\..\foobar_loop.jpg");
var digits = CharFA <string> .Repeat(
CharFA <string> .Set("0123456789"),
1, -1
, "Digits");
var word = CharFA <string> .Repeat(
CharFA <string> .Set(new CharRange[] { new CharRange('A', 'Z'), new CharRange('a', 'z') }),
1, -1
, "Word");
var whitespace = CharFA <string> .Repeat(
CharFA <string> .Set(" \t\r\n\v\f"),
1, -1
, "Whitespace");
var lexer = CharFA <string> .ToLexer(digits, word, whitespace);
lexer.RenderToFile(@"..\..\..\lexer.jpg");
var dopt = new CharFA <string> .DotGraphOptions();
dopt.DebugSourceNfa = lexer;
var dlexer = lexer.ToDfa();
dlexer.RenderToFile(@"..\..\..\dlexer.jpg", dopt
);
dlexer.RenderToFile(@"..\..\..\dlexer2.jpg");
var dom = RegexExpression.Parse("(ABC|DEF)+");
var fa = dom.ToFA("Accept");
fa.RenderToFile(@"..\..\..\ABCorDEFloop.jpg");
}