C# Class Pchp.Library.PerlRegex.RegexNode

Pass type as OneLazy or OneLoop

Removes redundant nodes from the subtree, and returns a reduced subtree.

Basic optimization. Single-letter alternations can be replaced by faster set specifications, and nested alternations with no intervening operators can be flattened: a|b|c|def|g|h -> [a-c]|def|[gh] apple|(?:orange|pear)|grape -> apple|orange|pear|grape

Basic optimization. Adjacent strings can be concatenated. (?:abc)(?:def) -> abcdef

Simple optimization. Once parsed into a tree, non-capturing groups serve no function, so strip them out.

Nested repeaters just get multiplied with each other if they're not too lumpy

Simple optimization. If a set is a singleton, an inverse singleton, or empty, it's transformed accordingly.

Simple optimization. If a concatenation or alternation has only one child strip out the intermediate node. If it has zero children, turn it into an empty.