61 lines
1.7 KiB
C#
61 lines
1.7 KiB
C#
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namespace Flee.Parsing
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{
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/**
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* A regular expression alternative element. This element matches
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* the longest alternative element.
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*/
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internal class AlternativeElement : Element
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{
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private readonly Element _elem1;
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private readonly Element _elem2;
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public AlternativeElement(Element first, Element second)
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{
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_elem1 = first;
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_elem2 = second;
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}
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public override object Clone()
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{
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return new AlternativeElement(_elem1, _elem2);
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}
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public override int Match(Matcher m,
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ReaderBuffer buffer,
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int start,
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int skip)
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{
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int length = 0;
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int length1 = -1;
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int length2 = -1;
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int skip1 = 0;
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int skip2 = 0;
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while (length >= 0 && skip1 + skip2 <= skip)
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{
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length1 = _elem1.Match(m, buffer, start, skip1);
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length2 = _elem2.Match(m, buffer, start, skip2);
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if (length1 >= length2)
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{
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length = length1;
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skip1++;
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}
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else
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{
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length = length2;
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skip2++;
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}
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}
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return length;
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}
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public override void PrintTo(TextWriter output, string indent)
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{
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output.WriteLine(indent + "Alternative 1");
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_elem1.PrintTo(output, indent + " ");
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output.WriteLine(indent + "Alternative 2");
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_elem2.PrintTo(output, indent + " ");
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}
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}
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}
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