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Diffstat (limited to 'common/patterns.js')
| -rw-r--r-- | common/patterns.js | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/common/patterns.js b/common/patterns.js new file mode 100644 index 0000000..f7da0ff --- /dev/null +++ b/common/patterns.js @@ -0,0 +1,187 @@ +/** + * Hydrilla/Lernette operations on page url patterns + * + * Copyright (C) 2021 Wojtek Kosior + * Redistribution terms are gathered in the `copyright' file. + */ + +const proto_re = "[a-zA-Z]*:\/\/"; +const domain_re = "[^/?#]+"; +const segments_re = "/[^?#]*"; +const query_re = "\\?[^#]*"; + +const url_regex = new RegExp(`\ +^\ +(${proto_re})\ +(${domain_re})\ +(${segments_re})?\ +(${query_re})?\ +#?.*\$\ +`); + +function deconstruct_url(url) +{ + const regex_match = url_regex.exec(url); + if (regex_match === null) + return undefined; + + let [_, proto, domain, path, query] = regex_match; + + domain = domain.split("."); + let path_trailing_dash = + path && path[path.length - 1] === "/"; + path = (path || "").split("/").filter(s => s !== ""); + path.unshift(""); + + return {proto, domain, path, query, path_trailing_dash}; +} + +/* Be sane: both arguments should be arrays of length >= 2 */ +function domain_matches(url_domain, pattern_domain) +{ + const length_difference = url_domain.length - pattern_domain.length; + + for (let i = 1; i <= url_domain.length; i++) { + const url_part = url_domain[url_domain.length - i]; + const pattern_part = pattern_domain[pattern_domain.length - i]; + + if (pattern_domain.length === i) { + if (pattern_part === "*") + return length_difference === 0; + if (pattern_part === "**") + return length_difference > 0; + if (pattern_part === "***") + return true; + return length_difference === 0 && pattern_part === url_part; + } + + if (pattern_part !== url_part) + return false; + } + + return pattern_domain.length === url_domain.length + 1 && + pattern_domain[0] === "***"; +} + +function path_matches(url_path, url_trailing_dash, + pattern_path, pattern_trailing_dash) +{ + const dashes_ok = !(pattern_trailing_dash && !url_trailing_dash); + + if (pattern_path.length === 0) + return url_path.length === 0 && dashes_ok; + + const length_difference = url_path.length - pattern_path.length; + + for (let i = 0; i < url_path.length; i++) { + if (pattern_path.length === i + 1) { + if (pattern_path[i] === "*") + return length_difference === 0; + if (pattern_path[i] === "**") { + return length_difference > 0 || + (url_path[i] === "**" && dashes_ok); + } + if (pattern_path[i] === "***") + return length_difference >= 0; + return length_difference === 0 && + pattern_path[i] === url_path[i] && dashes_ok; + } + + if (pattern_path[i] !== url_path[i]) + return false; + } + + return false; +} + +function url_matches(url, pattern) +{ + const url_deco = deconstruct_url(url); + const pattern_deco = deconstruct_url(pattern); + + if (url_deco === undefined || pattern_deco === undefined) { + console.log(`bad comparison: ${url} and ${pattern}`); + return false + } + + if (pattern_deco.proto !== url_deco.proto) + return false; + + return domain_matches(url_deco.domain, pattern_deco.domain) && + path_matches(url_deco.path, url_deco.path_trailing_dash, + pattern_deco.path, pattern_deco.path_trailing_dash); +} + +/* + * Call callback for every possible pattern that matches url. Return when there + * are no more patterns or callback returns false. + */ +function for_each_possible_pattern(url, callback) +{ + const deco = deconstruct_url(url); + + if (deco === undefined) { + console.log("bad url format", url); + return; + } + + for (let d_slice = 0; d_slice < deco.domain.length; d_slice++) { + const domain_part = deco.domain.slice(d_slice).join("."); + const domain_wildcards = []; + if (d_slice === 0) + domain_wildcards.push(""); + if (d_slice === 1) + domain_wildcards.push("*."); + if (d_slice > 0) + domain_wildcards.push("**."); + domain_wildcards.push("***."); + + for (const domain_wildcard of domain_wildcards) { + const domain_pattern = domain_wildcard + domain_part; + + for (let s_slice = deco.path.length; s_slice > 0; s_slice--) { + const path_part = deco.path.slice(0, s_slice).join("/"); + const path_wildcards = []; + if (s_slice === deco.path.length) { + if (deco.path_trailing_dash) + path_wildcards.push("/"); + path_wildcards.push(""); + } + if (s_slice === deco.path.length - 1 && + deco.path[s_slice] !== "*") + path_wildcards.push("/*"); + if (s_slice < deco.path.length && + (deco.path[s_slice] !== "**" || + s_slice < deco.path.length - 1)) + path_wildcards.push("/**"); + if (deco.path[s_slice] !== "***" || s_slice < deco.path.length) + path_wildcards.push("/***"); + + for (const path_wildcard of path_wildcards) { + const path_pattern = path_part + path_wildcard; + + const pattern = deco.proto + domain_pattern + path_pattern; + + if (callback(pattern) === false) + return; + } + } + } + } +} + +function possible_patterns(url) +{ + const patterns = []; + for_each_possible_pattern(url, patterns.push); + + return patterns; +} + +/* + * EXPORTS_START + * EXPORT url_matches + * EXPORT for_each_possible_pattern + * EXPORT possible_patterns + * EXPORTS_END + */ |