Lua.VM.Stdlib.Pattern (Lua v1.0.0-rc.2)
View SourceLua 5.3 pattern matching engine.
Implements Lua's pattern language, which is NOT regex but a simpler custom syntax:
- Character classes: %a (letters), %d (digits), %l (lowercase), %u (uppercase), %w (alphanumeric), %s (whitespace), %p (punctuation), %c (control), . (any)
- Quantifiers: * (0+ greedy), + (1+ greedy), - (0+ lazy), ? (0 or 1)
- Anchors: ^ (start), $ (end)
- Sets: [abc], [^abc], [%a%d]
- Captures: (pattern), %1-%9 backreferences
- Balanced: %bxy
- Escape: % + non-alphanumeric = literal
Summary
Functions
Compile a pattern string into a list of pattern elements.
Returns {anchored, elements}.
Find first match of pattern in subject starting at position init (1-based).
Returns {start, stop, captures} or :nomatch.
Global match - returns list of all matches as {start, stop, captures}.
Global substitution. Returns {result_string, count}.
Stateful global substitution. Returns {result_string, count, state}.
Match pattern against subject, returning captures or :nomatch.
Functions
Compile a pattern string into a list of pattern elements.
Returns {anchored, elements}.
Find first match of pattern in subject starting at position init (1-based).
Returns {start, stop, captures} or :nomatch.
Global match - returns list of all matches as {start, stop, captures}.
Global substitution. Returns {result_string, count}.
repl is one of: binary (string), function (arity 1, args -> result), or
any other term (treated as a no-op, returning the whole match).
This entry point does NOT thread Lua VM state through the function
replacement — any side effects in the callback (upvalue mutation, table
writes) are dropped on the floor. For Lua-level string.gsub use
gsub_stateful/5 instead.
Stateful global substitution. Returns {result_string, count, state}.
When repl is a function it must have arity 2 — (args, state) -> {result, state}
— so callbacks that mutate Lua state (upvalues, tables) thread their
changes back out. String and table replacements are state-pass-through.
Match pattern against subject, returning captures or :nomatch.