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Diffstat (limited to 'docs/dev')
| -rw-r--r-- | docs/dev/regex-porting.md | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/docs/dev/regex-porting.md b/docs/dev/regex-porting.md index 45033044..d0686982 100644 --- a/docs/dev/regex-porting.md +++ b/docs/dev/regex-porting.md @@ -27,6 +27,19 @@ 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. +## `A` (anchored) modifier + +The PCRE `A` modifier requires the match to start exactly at the search offset. The `regex` crate +anchors a pattern only at the head of the haystack. + +Port such a pattern by searching the sub-slice that begins at the offset, with a `^` in place of +the `A` modifier: + +```rust +// PHP: preg_match('/foo/A', $subject, offset: $offset) +preg_match(php_regex!(r"/^foo/"), &subject[offset..]) +``` + ## Port other unsupported features ad hoc For any other PCRE feature the `regex` crate does not support (conditional subpatterns, |