18 lines
951 B
Text
18 lines
951 B
Text
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The re_graph.pl program graphs regular expressions. The guts of the regular
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expression engine is a simple state machine. The various states and operations
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in the regular expression parser can be displayed using a surprisingly simple
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diagram.
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A few notes on what you are looking at:
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* The nodes Start and Stop denote the beginning and end of the regular
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expression.
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* The solid squares denote atoms. Lines indicate the next state. When a
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line splits, the state machine will take the top line first. If it's
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path is blocked it will backup and take the next lower line. This is
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repeated until it finds a path to the end or all paths are exhausted.
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* Brown boxes indicate a grouping operation, i.e. ().
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* Green boxes indicate a zero with test. The state machine will perform the
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test inside the box before moving ahead.
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WWW: http://www.oualline.com/sw/
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