public IEnumerable <Bytecode> Compile(Parser.RegularExpression e)
{
this.groupcounter = 0;
this.labelcounter = 0;
foreach (var item in InternalCompile(e))
{
yield return(item);
}
yield return(new Match {
});
}
private IEnumerable <Bytecode> InternalCompile(Parser.RegularExpression e)
{
if (e is Parser.Primitive)
{
var prim = e as Parser.Primitive;
yield return(new Symbol {
Lo = prim.Lo, Hi = prim.Hi
});
}
else if (e is Parser.Sequence)
{
var seq = e as Parser.Sequence;
var left = InternalCompile(seq.Left);
var right = InternalCompile(seq.Right);
foreach (var item in left.Concat(right))
{
yield return(item);
}
}
else if (e is Parser.Group)
{
var group = e as Parser.Group;
var id = this.groupcounter++;
yield return(new Save {
Id = 2 * id
});
foreach (var item in InternalCompile(group.Re))
{
yield return(item);
}
yield return(new Save {
Id = 2 * id + 1
});
}
else if (e is Parser.Or)
{
var choice = e as Parser.Or;
var l1 = new Label {
Location = this.labelcounter++
};
var l2 = new Label {
Location = this.labelcounter++
};
var l3 = new Label {
Location = this.labelcounter++
};
var e1 = InternalCompile(choice.Left);
var e2 = InternalCompile(choice.Right);
yield return(new Fork {
Fst = l1, Snd = l2
});
yield return(l1);
foreach (var item in e1)
{
yield return(item);
}
yield return(new Jump {
Where = l3
});
yield return(l2);
foreach (var item in e2)
{
yield return(item);
}
yield return(l3);
}
else if (e is Parser.Star)
{
var star = e as Parser.Star;
var l1 = new Label {
Location = this.labelcounter++
};
var l2 = new Label {
Location = this.labelcounter++
};
var l3 = new Label {
Location = this.labelcounter++
};
var e1 = InternalCompile(star.Re);
yield return(l1);
if (star.Greedy)
{
yield return new Fork {
Fst = l2, Snd = l3, Greedy = true
}
}
;
else
{
yield return new Fork {
Fst = l3, Snd = l2, Greedy = false
}
};
yield return(l2);
foreach (var item in e1)
{
yield return(item);
}
yield return(new Jump {
Where = l1
});
yield return(l3);
}
else if (e is Parser.Plus)
{
var plus = e as Parser.Plus;
var l1 = new Label {
Location = this.labelcounter++
};
var l2 = new Label {
Location = this.labelcounter++
};
var l3 = new Label {
Location = this.labelcounter++
};
var e1 = InternalCompile(plus.Re);
yield return(l1);
foreach (var item in e1)
{
yield return(item);
}
if (plus.Greedy)
{
yield return new Fork {
Fst = l1, Snd = l3, Greedy = true
}
}
;
else
{
yield return new Fork {
Fst = l3, Snd = l1, Greedy = false
}
};
yield return(l3);
}
else if (e is Parser.Question)
{
throw new Exception("Finish types");
}
yield break;
}
