It uses about 56 MB less memory when LOOT launches into my Skyrim SE
large test load order with the latest masterlist and prelude, and
explicitly targets ECMAScript-like syntax like C++ std::regex does,
though supports newer functionality.
Compared to fancy-regex's syntax support, regress adds support for the
\0 nul character escape and removes support for:
- modifiers (e.g. `(?i)`)
- some Unicode character classes (e.g. used with `\p{}` and `\P{}`)
- the ASCII/POSIX character classes (e.g. `[:alpha:]`)
- various character escapes, including \A \a \z \b{start} \<
\b{end} \> \b{start-half} \b{end-half}
- (?P<name>exp) named capture groups
However, since regress's v flag requires more characters to be escaped
inside character classes than fancy-regex's Unicode support requires,
it's not used, so that further restricts the supported Unicode character
classes, and means that character class intersection, union and
subtraction syntaxes aren't supported.
The nul character escape is irrelevant for filename matching as it's not
allowed in Windows or Linux filenames.
Compared to C++ std::regex, the new restrictions are:
- the lack of support for ASCII/POSIX character classes
- the lack of support for control character escapes (e.g. `\cX`)
The lack of support for control character escapes is irrelevant as
control characters aren't allowed in Windows filenames.
A search of the masterlists doesn't find any use of the ASCII character
classes, and it's very unlikely that any user metadata would use them.
If such syntax is in use, it'll cause an error.
fancy-regex supports more syntax than C++ std::regex, but for the syntax
that they both accept:
- std::regex matches . against a single character, fancy-regex matches
it against a Unicode codepoint
- \w \W \d \D \s \S \b and \B are locale-dependent in std::regex but
Unicode-aware and locale-independent in fancy-regex
- case-insensitive comparisons are locale-dependent in std::regex but
are Unicode-aware and locale-independent in fancy-regex
- std::regex supports \0 and \cX escapes, where X is in [A-Za-z] but
fancy-regex does not. This is not significant for libloot's usage as
nul and control characters are not allowed in Windows filenames.
- std::regex treats \< and \> as < and > respectively, but fancy-regex
treats them as start- and end-of-word boundary assertions
respectively. This is not significant for libloot's usage as they are
not allowed in Windows filenames.
- std::regex allows a literal [ to appear within a character class, but
fancy-regex requires it to be escaped.
These differences are unlikely to cause any issues.
- The string encoding and errors sections move to the reference page
- The metadata files section moves to the introduction page
- The language codes section is already detailed in a C++ header doc comment
- The caching section is already detailed in C++ header doc comments
- The performance section is outdated and isn't worth keeping once updated.
Throw std::runtime_error for all esplugin errors except ESP_ERROR_PLUGIN_METADATA_NOT_FOUND, which causes a PluginNotLoadedError to be thrown, since LOOT needs to be able to distinguish that error.
Oliver Hamlet