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mruby-regexp: read the \u escape #7074

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Merged
matz merged 3 commits into from
Aug 10, 2026
Merged

mruby-regexp: read the \u escape #7074

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8a4580c
mruby-regexp: extract the pieces a codepoint escape needs
takumin Aug 10, 2026
048e5da
mruby-regexp: read the `\u` escape
takumin Aug 10, 2026
0b665e3
mruby-regexp: assert which refusal the `\u` patterns reach
takumin Aug 10, 2026
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17 changes: 17 additions & 0 deletions mrbgems/mruby-regexp/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,21 @@ simulation) with backtracking fallback.
- `(?<=...)` positive lookbehind (fixed-length only)
- `(?<!...)` negative lookbehind (fixed-length only)

### Character Escapes

- `\n`, `\t`, `\r`, `\f`, `\v`, `\a`, `\e` control characters
- `\NNN` octal, one to three digits
- `\xHH` hex, one or two digits
- `\uXXXX` Unicode codepoint, exactly four hex digits
- `\u{...}` Unicode codepoints, one to six hex digits each, several of
them separated by spaces: `/\u{61 62}/` is `ab`

Outside a character class the list form is a sequence rather than one
atom, so a quantifier after it repeats the last codepoint only:
`/\u{61 62}+/` is `ab+`. Inside a class every codepoint is a member of
its own, and the last one can still open a range: `/[\u{61 62}-z]/` is
`a` plus `b-z`.

### Anchors

- `^` beginning of line
Expand Down Expand Up @@ -148,6 +163,8 @@ pattern analysis.
Maximum 255 bytes.
- **No Unicode properties**: `\p{Alpha}`, `\p{L}`, etc. are not
supported.
- **No `\x{...}` hex escape**: the hex escape is `\xHH`, so it reaches
`0xff` at most. Write `\u{...}` for a codepoint above that.
- **ASCII case folding by default**: The `i` flag handles ASCII letters
only unless the build defines `MRB_REGEXP_UNICODE_CASE`, which adds the
Unicode foldings that pair one codepoint with one other. Without the
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1 change: 1 addition & 0 deletions mrbgems/mruby-regexp/include/re_internal.h
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Expand Up @@ -161,6 +161,7 @@ void mrb_re_free(mrb_state *mrb, mrb_regexp_pattern *pat);
/* UTF-8 helpers */
int mrb_re_utf8_charlen(const char *s, const char *end);
uint32_t mrb_re_utf8_decode(const char *s, const char *end, int *len);
int mrb_re_utf8_encode(uint32_t cp, char *buf);
mrb_bool mrb_re_is_word_char(uint32_t c);

/* The two foldings whose result is an ASCII letter. Every build carries them,
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