diff options
Diffstat (limited to 'common/patterns_query_tree.js')
| -rw-r--r-- | common/patterns_query_tree.js | 113 |
1 files changed, 59 insertions, 54 deletions
diff --git a/common/patterns_query_tree.js b/common/patterns_query_tree.js index ea3607e..8d01cc1 100644 --- a/common/patterns_query_tree.js +++ b/common/patterns_query_tree.js @@ -3,7 +3,7 @@ * * Function: Data structure to query items by URL patterns. * - * Copyright (C) 2021 Wojtek Kosior + * Copyright (C) 2021, 2022 Wojtek Kosior <koszko@koszko.org> * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -41,8 +41,6 @@ * proprietary program, I am not going to enforce this in court. */ -// TODO! Modify the code to use `Object.create(null)` instead of `{}`. - #FROM common/patterns.js IMPORT deconstruct_url /* "Pattern Tree" is how we refer to the data structure used for querying @@ -53,44 +51,48 @@ const pattern_tree_make = () => ({}) #EXPORT pattern_tree_make AS make -function empty_node() { - return { - wildcard_matches: [null, null, null], - literal_match: null, - children: {} - }; -} +const empty_node = () => ({}); function is_empty_node(tree_node) { - const children = tree_node.children; - for (const key in children) { - if (children.hasOwnProperty(key)) - return false; - } - - if (tree_node.wildcard_matches.reduce((a, b) => b && a !== null, 1)) + for (const key in tree_node) return false; - return tree_node.literal_match === null; + return true; } +const wildcard_matches = node => [node["*"], node["**"], node["***"]]; + const is_wildcard = segment => ["*", "**", "***"].lastIndexOf(segment) >= 0; /* + * Remove reference to given child fron node and leave the node in consistent + * state afterwards, i.e. remove the "c" property if no childs are left. + */ +function delete_child(node, child_name) { + if (node.c) { + delete node.c[child_name]; + + for (const key in node.c) + return; + + delete node.c; + } +} + +/* * Yields all matches of this segments sequence against the tree that starts at * this node. Results are produces in order from greatest to lowest pattern * specificity. */ -function* search_sequence(tree_node, segments) -{ +function* search_sequence(tree_node, segments) { const nodes = [tree_node]; - for (const segment of segments) { - const next_node = nodes[nodes.length - 1].children[segment]; - if (next_node === undefined) + for (const current_segment of segments) { + const children = nodes[nodes.length - 1].c || {}; + if (!Object.hasOwnProperty.call(children, current_segment)) break; - nodes.push(next_node); + nodes.push(children[current_segment]); } const nsegments = segments.length; @@ -106,10 +108,11 @@ function* search_sequence(tree_node, segments) while (nodes.length) { const node = nodes.pop(); - const items = [node.literal_match, ...node.wildcard_matches]; + const literal_match = node.l; + const items = [literal_match, ...wildcard_matches(node)]; - for (let i = 0; i < 4; i++) { - if (items[i] !== null && conds[i]()) + for (let i = 0; i < items.length; i++) { + if (items[i] !== undefined && conds[i]()) yield items[i]; } } @@ -129,53 +132,60 @@ function* search_sequence(tree_node, segments) * segments and value returned by item_modifier is not `null`, make the value * queryable by this path. */ -function modify_sequence(tree_node, segments, item_modifier) -{ +function modify_sequence(tree_node, segments, item_modifier) { const nodes = [tree_node]; let removed = true; for (var current_segment of segments) { - const child = tree_node.children[current_segment] || empty_node(); - tree_node.children[current_segment] = child; + const children = tree_node.c || {}; + tree_node.c = children; + + const child = Object.hasOwnProperty.call(children, current_segment) ? + children[current_segment] : empty_node(); + children[current_segment] = child; + tree_node = child; nodes.push(tree_node); } - tree_node.literal_match = item_modifier(tree_node.literal_match); - if (tree_node.literal_match !== null) + tree_node.l = item_modifier(tree_node.l || null); + if (tree_node.l === null) + delete tree_node.l; + else removed = false; let i = segments.length; if (is_wildcard(current_segment)) { - const asterisks = current_segment.length - 1; - const wildcards = nodes[i - 1].wildcard_matches; - wildcards[asterisks] = item_modifier(wildcards[asterisks]); - if (wildcards[asterisks] !== null) + nodes[i - 1][current_segment] = + item_modifier(nodes[i - 1][current_segment] || null); + if (nodes[i - 1][current_segment] === null) + delete nodes[i - 1][current_segment]; + else removed = false; } - while (!removed) + if (!removed) return; while (i > 0) { tree_node = nodes[i--]; if (is_empty_node(tree_node)) - delete nodes[i].children[segments[i]]; + delete_child(nodes[i], segments[i]); + else + break; } } /* Helper function for modify_tree(). */ -function modify_path(tree_node, deco, item_modifier) -{ +function modify_path(tree_node, deco, item_modifier) { tree_node = tree_node || empty_node(); modify_sequence(tree_node, deco.path, item_modifier); return is_empty_node(tree_node) ? null : tree_node; } /* Helper function for modify_tree(). */ -function modify_domain(tree_node, deco, item_modifier) -{ +function modify_domain(tree_node, deco, item_modifier) { const path_modifier = branch => modify_path(branch, deco, item_modifier); tree_node = tree_node || empty_node(); /* We need an array of domain labels ordered most-significant-first. */ @@ -184,8 +194,7 @@ function modify_domain(tree_node, deco, item_modifier) } /* Helper function for pattern_tree_register() and pattern_tree_deregister(). */ -function modify_tree(patterns_by_proto, pattern, item_modifier) -{ +function modify_tree(patterns_by_proto, pattern, item_modifier) { /* * We pass 'false' to disable length limits on URL parts. Length limits are * mostly useful in case of iteration over all patterns matching given URL. @@ -208,8 +217,7 @@ function modify_tree(patterns_by_proto, pattern, item_modifier) * Make item queryable through the Pattern Tree that starts with the protocols * dictionary object passed in the first argument. */ -function pattern_tree_register(patterns_by_proto, pattern, item_name, item) -{ +function pattern_tree_register(patterns_by_proto, pattern, item_name, item) { const key_prefix = pattern[pattern.length - 1] === '/' ? '/' : '_'; item_name = key_prefix + item_name; const add_item = obj => Object.assign(obj || {}, {[item_name]: item}); @@ -218,8 +226,7 @@ function pattern_tree_register(patterns_by_proto, pattern, item_name, item) #EXPORT pattern_tree_register AS register /* Helper function for pattern_tree_deregister(). */ -function _remove_item(obj, item_name) -{ +function _remove_item(obj, item_name) { obj = obj || {}; delete obj[item_name]; for (const key in obj) @@ -233,8 +240,7 @@ function _remove_item(obj, item_name) * should be pattern and name that have been earlier passed to * pattern_tree_register(). */ -function pattern_tree_deregister(patterns_by_proto, pattern, item_name) -{ +function pattern_tree_deregister(patterns_by_proto, pattern, item_name) { const key_prefix = pattern[pattern.length - 1] === '/' ? '/' : '_'; item_name = key_prefix + item_name; const remove_item = obj => _remove_item(obj, item_name); @@ -244,12 +250,11 @@ function pattern_tree_deregister(patterns_by_proto, pattern, item_name) /* * Yield registered items that match url. Each yielded value is an object with - * key being matched item names and values being the items. One such object + * keys being matched item names and values being the items. One such object * shall contain all items matched with given pattern specificity. Objects are * yielded in order from greatest to lowest pattern specificity. */ -function* pattern_tree_search(patterns_by_proto, url) -{ +function* pattern_tree_search(patterns_by_proto, url) { const deco = deconstruct_url(url, false); const tree_for_proto = patterns_by_proto[deco.proto] || empty_node(); |