lpeg.Cf

Lua function lpeg.Cf Summary Creates a fold capture Prototype lpeg.Cf (patt, func) Description If patt produces a list of captures C1 C2 ... Cn, this capture will produce the value func(...func(func(C1, C2), C3)..., Cn), that is, it will fold (or accumulate, or reduce) the captures from patt using function func. This capture assumes that patt should produce at least one capture with at least one value (of any type), which becomes the initial value of an accumulator. (If you need a specific initial value, you may prefix a constant capture to patt.) For each subsequent capture LPeg calls func with this accumulator as the first argument and all values produced by the capture as extra arguments; the value returned by this call becomes the new value for the accumulator. The final value of the accumulator becomes the captured value. As an example, the following pattern matches a list of numbers separated by commas and returns their addition: -- matches a numeral and captures its value number = lpeg.R"09"^1 / tonumber -- matches a list of numbers, captures their values list = number * ("," * number)^0 -- auxiliary function to add two numbers function add (acc, newvalue) return acc + newvalue end -- folds the list of numbers adding them sum = lpeg.Cf(list, add) -- example of use print(sum:match("10,30,43")) --> 83 See Also ... Topics Lua bc (big number) functions Lua bit manipulation functions Lua LPEG library Lua package functions Lua PCRE regular expression functions Lua script extensions Lua string functions Lua table functions Lua utilities Regular Expressions Scripting Lua functions lpeg.C (Creates a simple capture) lpeg.Carg (Creates an argument capture) lpeg.Cb (Creates a back capture) lpeg.Cc (Creates a constant capture) lpeg.Cg (Creates a group capture) lpeg.Cmt (Creates a match-time capture) lpeg.Cp (Creates a position capture) lpeg.Cs (Creates a substitution capture) lpeg.Ct (Creates a table capture) lpeg.locale (Returns a table of patterns matching the current locale) lpeg.match (Matches a pattern against a string) lpeg.P (Converts a value into a pattern) lpeg.print (Outputs debugging information to stdout) lpeg.R (Returns a pattern that matches a range of characters) lpeg.S (Returns a pattern that matches a set of characters) lpeg.type (Tests if a value is a pattern) lpeg.V (Creates a non-terminal variable for a grammar) lpeg.version (Returns the LPeg version) (Help topic: lua=lpeg.Cf) Documentation contents page