diff options
| -rw-r--r-- | ChangeLog | 7 | ||||
| -rw-r--r-- | filter.c | 3 | ||||
| -rw-r--r-- | txr.1 | 58 |
3 files changed, 68 insertions, 0 deletions
@@ -1,3 +1,10 @@ +2014-08-09 Kaz Kylheku <kaz@kylheku.com> + + * filter.c (filter_init): Expose the trie-lookup-begin, + trie-value-at and trie-lookup-feed-char functions as intrinsics. + + * txr.1: Document exposed functions. + 2014-08-08 Kaz Kylheku <kaz@kylheku.com> Bugfix: ret operator does not generate functions @@ -724,6 +724,9 @@ void filter_init(void) reg_fun(intern(lit("trie-add"), user_package), func_n3(trie_add)); reg_fun(intern(lit("trie-compress"), user_package), func_n1(trie_compress_intrinsic)); + reg_fun(intern(lit("trie-lookup-begin"), user_package), func_n1(trie_lookup_begin)); + reg_fun(intern(lit("trie-value-at"), user_package), func_n1(trie_value_at)); + reg_fun(intern(lit("trie-lookup-feed-char"), user_package), func_n2(trie_lookup_feed_char)); reg_fun(intern(lit("filter-string-tree"), user_package), func_n2(filter_string_tree)); reg_fun(intern(lit("filter-equal"), user_package), func_n4(filter_equal)); reg_fun(intern(lit("url-encode"), user_package), func_n2o(url_encode, 1)); @@ -14938,6 +14938,64 @@ while at the same time still modifying the internals of <trie>. Consequently, the program should not retain the input object <trie>, but use the returned object in its place. +.SS Function trie-lookup-begin + +.TP +Syntax: + + (trie-lookup-begin <trie>) + +.TP +Description: + +The trie-lookup-begin function returns a context object for performing +an open-coded lookup traversal of a trie. The <trie> argument +is expected to be a trie that was created by the make-trie function. + +.SS Function trie-lookup-feed-char + +.TP +Syntax: + + (trie-lookup-feed-char <trie-context> <char>) + +.TP +Description: + +The trie-lookup-feed-char function performs a one character step in a trie +lookup. The <trie-context> argument must be a trie contxt returned +by trie-lookup-begin, or by some previous call to trie-lookup-feed-char. +The <char> argument is the character to search for. + +If the lookup is successful (the match through the trie can continue +with the given character) then a new trie context object is returned. +The old trie context remains valid. + +If the lookup is unsuccessful, nil is returned. + +Note: determining whether a given string is stored in a trie can be +performed looking up every character of the string successively +with trie-lookup-feed-char, using the newly returned context +for each successive operation. If every character is found, it means +that either that exact string is found in the trie, or a prefix. +The ambiguity can be resolved by testing whether the trie has a value +at the last node using tree-value-at. For instance, if "catalog" +is inserted into an empty trie with value "foo", then "cat" will look up +successfully, being a prefix of "catalog"; however, the value at "cat" is nil. + +.SS Function tree-value-at + +.TP +Syntax: + + (trie-value-at <trie-context>) + +.TP +Description: + +The trie-value-at function returns the value stored at the node in +in the trie given by <trie-context>. Nodes which have not been given +a value hold the value nil. .SS Function filter-string-tree |