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C and Lua wrappers for RE2
C and Lua wrapper for RE2 regular expression library. The Lua wrapper is built on top of C wrapper.
Lua Functions
The Lua wrapper (lua-re2.lua) exposes following functions:
new
syntax: instance = new()
Create an instance which pre-allocate some data structures for captures, to obviate
the need of allocating them each time match is called.
The default value of the parameter max-capture is 40.
compile
syntax: pattern, capture_num, err_msg = compile(pattern, [options, max_mem])
Pre-compile the pattern string. Additional options for the regex engine can be passed by
the options and max_mem; they are corresponding to RE2's re2::RE2::Options except
that the options is using single character, instead of bitmask, to pass the boolean
options. The respondance between options and RE2's re2::RE2::Options are following:
| option char | re2::RE2::Options | meaning | default value |
|---|---|---|---|
| u | utf8 | text and pattern are UTF-8; otherwise Latin-1 | true |
| a | longest_match | search for longest match, not first match | false |
| e | log_errors | log syntax and execution errors to ERROR | true |
| l | literal | interpret string as literal, not regexp | false |
| n | never_nl | never match \n, even if it is in regexp | false |
| s | dot_nl | dot matches everything including new line | false |
| c | never_capture | parse all parens as non-capturing | false |
| i | case_sensitive | match is case-sensitive (regexp can override with (?i) unless in posix_syntax mode) | true |
| m | multi-line-mode | ^ match after any newline, and $ match any before newline | false |
match
syntax: captures, errmsg = match(instance, pattern, text, cap_idx)
Match the given pre-compiled pattern against the text. It returns three variables:
| captures | the specified capture(s), see bellow |
| errmsg | error message if something wrong took place |
The input parameter cap_idx can take one of the following values:
| -1 | return all captures in an array, i-th (i>=0) element contains i-th capture, and 0-th element is the sub-string which tighly matches the entire pattern|
| 1 .. the-number-of-capture | return particular capture |
find
syntax: match_or_not = find(pattern, text)
return non-nil if match, nil otherwise
match_r
syntax: captures = match_r(instance, pattern, text)
Match the given pre-compiled pattern repeatedly through the full text.
It returns all captures in an array if match, nil otherwise.
C Funtions
The interface functions are self-descriptive. Please check the re2c_c.h for details.