diff options
| -rw-r--r-- | crates/shirabe-external-packages/src/composer/pcre/preg.rs | 2 | ||||
| -rw-r--r-- | crates/shirabe/src/util/platform.rs | 9 | ||||
| -rw-r--r-- | docs/dev/regex-porting.md | 39 |
3 files changed, 48 insertions, 2 deletions
diff --git a/crates/shirabe-external-packages/src/composer/pcre/preg.rs b/crates/shirabe-external-packages/src/composer/pcre/preg.rs index 1ff7dc6..2c7430d 100644 --- a/crates/shirabe-external-packages/src/composer/pcre/preg.rs +++ b/crates/shirabe-external-packages/src/composer/pcre/preg.rs @@ -8,6 +8,8 @@ //! - `UnexpectedNullMatchException`: thrown by the `Preg::*StrictGroups()` variants when a capture //! group did not participate. Those variants were dropped because Rust's `Option` already //! distinguishes participating from non-participating groups. +//! +//! See docs/dev/regex-porting.md for more detailed regex porting rules. use indexmap::IndexMap; use shirabe_php_shim::{ diff --git a/crates/shirabe/src/util/platform.rs b/crates/shirabe/src/util/platform.rs index 797bac2..7c9f569 100644 --- a/crates/shirabe/src/util/platform.rs +++ b/crates/shirabe/src/util/platform.rs @@ -101,11 +101,16 @@ impl Platform { ); } + // Regex pattern compatibility: + // The original pattern uses a conditional subpattern to make the trailing `%` required + // only for the `%VAR%` form. The Rust regex crate does not support conditionals, so the + // two forms are written as an explicit alternation: `$VAR` or `%VAR%`. Preg::replace_callback( - r"#^(\$|(?P<percent>%))(?P<var>\w++)(?(percent)%)(?P<path>.*)#", + r"#^(?:\$(?P<dvar>\w+)|%(?P<pvar>\w+)%)(?P<path>.*)#", |matches: &indexmap::IndexMap<CaptureKey, String>| -> String { let var = matches - .get(&CaptureKey::ByName("var".to_string())) + .get(&CaptureKey::ByName("dvar".to_string())) + .or_else(|| matches.get(&CaptureKey::ByName("pvar".to_string()))) .map(|s| s.as_str()) .unwrap_or(""); let path_part = matches diff --git a/docs/dev/regex-porting.md b/docs/dev/regex-porting.md new file mode 100644 index 0000000..4503304 --- /dev/null +++ b/docs/dev/regex-porting.md @@ -0,0 +1,39 @@ +# Regex porting + +Composer uses PHP's `preg_*` functions (backed by PCRE). Shirabe ports these to the Rust +[`regex`](https://docs.rs/regex) crate. Because PCRE and the `regex` crate have different feature +sets, follow the rules below when porting. + +## Do not introduce a PCRE crate + +The `regex` crate is not based on PCRE library and does not support some features that PCRE does. + +Even when such a feature is needed, do not introduce a PCRE-family crate such as `pcre2`. Either +rewrite the pattern into a form the `regex` crate can express, or decompose it into hand-written +logic that does not use a regular expression. + +## Panic on pattern compile failure + +When a pattern fails to compile, `panic!`. Do not wrap it in a `Result` and propagate it to the +caller. + +This reflects a design assumption that Composer-derived patterns always compile successfully at +runtime: a compile failure is not a recoverable error but a programming mistake (or a porting bug). + +## Do not port performance-only possessive quantifiers + +When a PCRE possessive quantifier (`++`, `*+`, `?+`, etc.) is used solely to suppress backtracking +for performance, replace it with the plain quantifier (`+`, `*`, `?`). + +The `regex` crate never backtracks, so it has no possessive quantifiers and has no need for them. + +## Port other unsupported features ad hoc + +For any other PCRE feature the `regex` crate does not support (conditional subpatterns, +backreferences, etc.), port it case by case. When you do, make the transformation explicit with a +comment in the following form: + +``` +// Regex pattern compatibility: +// <description> +``` |