https://bugzilla.wikimedia.org/show_bug.cgi?id=164
--- Comment #207 from Philippe Verdy <verd...@wanadoo.fr> 2010-08-04 17:41:52 UTC --- In reply to comment #206) Top-down analyzers are very easy to write, provided that you allow parsing to be made via TWO generation points, instead of one: the first one converts and accumulates the tokens in an array as long as it is not able to be processable as a whole; this requiers a first parsing loop. Then the final step will ask the expansion of parsed tokens lazily, in a basic processing loop which will "eat" the tokens lazily, replacing them by their expansion, until there remains only one token, a basic string that can be used as an expanded parameter. I may try working on it, it's not so complicate to formulate, even without using Yacc/bison/PCTCS, I have many ideas on how it will work : basically each non-terminal token in the formal syntax becomes TWO functions, one is used when parsing individual tokens, until the last one is reached, then a second function will be used to expand itself, that will be used later (after returning from the BY the caller, and ONLY when it will need the expansion in its OWN expansion function. For example the MediaWiki parser would become TWO functions: mediawiki_parse() (which returns an array of tokens) and mediawiki_expand() which is stored as the first token in the array. All ..._expand() functions would have two parameters: one for the context in which they are to be evaluated (containing for example time properties, cache properties, language properties ), and the array itself to be expanded up to the end until they produce some simple text The main concept is that tokens will expand lazily, but with full control by the non-terminal parsed token which knows its context of expansion. Basically the first step for each non-terminal token in the formal grammar is performing a bottom-up conversion, from a top-down analysis (performed recursively); this first step builds a AST tree (stored as a basic array of children). The second step is performing a *conditional* top-down expansion of the AST array into a flat text, ignoring nodes that don't need to be expanded as their effective expansion will not be needed for the expansion of the current AST node. Both steps are recursive, but in separate simple processing loops. OK this is still out of topic, but I don't know for now where to post these concepts. I'll stop discussing this here. -- Configure bugmail: https://bugzilla.wikimedia.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug. _______________________________________________ Wikibugs-l mailing list Wikibugs-l@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikibugs-l
