MUSHclient documentation: lpeg.Cg

lpeg.Cg

lpeg.Cg
Lua function lpeg.Cg Summary Creates a group capture Prototype `lpeg.Cg (patt [, name])` Description It groups all values returned by patt into a single capture. The group may be anonymous (if no name is given) or named with the given name. An anonymous group serves to join values from several captures into a single capture. A named group has a different behavior. In most situations, a named group returns no values at all. Its values are only relevant for a following back capture or when used inside a table capture. This example parses a list of name-value pairs and returns a table with those pairs: lpeg.locale(lpeg) local space = lpeg.space^0 local name = lpeg.C(lpeg.alpha^1) * space local sep = lpeg.S(",;") * space local pair = lpeg.Cg(name * "=" * space * name) * sep^-1 local list = lpeg.Cf(lpeg.Ct("") * pair^0, rawset) t = list:match("a=b, c = hi; next = pi") --> { a = "b", c = "hi", next = "pi" } Each pair has the format name = name followed by an optional separator (a comma or a semicolon). The pair pattern encloses the pair in a group pattern, so that the names become the values of a single capture. The list pattern then folds these captures. It starts with an empty table, created by a table capture matching an empty string; then for each capture (a pair of names) it applies rawset over the accumulator (the table) and the capture values (the pair of names). rawset returns the table itself, so the accumulator is always the table. 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.Cf (Creates a fold 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.Cg) Documentation contents page

Lua function

lpeg.Cg

Summary

Creates a group capture

Prototype

lpeg.Cg (patt [, name])

Description

It groups all values returned by patt into a single capture. The group may be anonymous (if no name is given) or named with the given name.



An anonymous group serves to join values from several captures into a single capture. A named group has a different behavior. In most situations, a named group returns no values at all. Its values are only relevant for a following back capture or when used inside a table capture.



This example parses a list of name-value pairs and returns a table with those pairs:



lpeg.locale(lpeg)



local space = lpeg.space^0

local name = lpeg.C(lpeg.alpha^1) * space

local sep = lpeg.S(",;") * space

local pair = lpeg.Cg(name * "=" * space * name) * sep^-1

local list = lpeg.Cf(lpeg.Ct("") * pair^0, rawset)

t = list:match("a=b, c = hi; next = pi")  --> { a = "b", c = "hi", next = "pi" }



Each pair has the format name = name followed by an optional separator (a comma or a semicolon). The pair pattern encloses the pair in a group pattern, so that the names become the values of a single capture. The list pattern then folds these captures. It starts with an empty table, created by a table capture matching an empty string; then for each capture (a pair of names) it applies rawset over the accumulator (the table) and the capture values (the pair of names). rawset returns the table itself, so the accumulator is always the table.