View source: R/charInSetParser.R
charInSetParser | R Documentation |
Recognises a single character satisfying a predicate function.
charInSetParser(fun, action = function(s) list(type="charInSet",value=s), error = function(p) list(type="charInSet",pos =p))
fun |
Function to determine if character belongs to a set. Argument "fun" is a signature function: character -> logical (boolean) |
action |
Function to be executed if recognition succeeds. Character stream making up the token is passed as parameter to this function |
error |
Function to be executed if recognition does not succeed. Position of |
Anonymous function, returning a list.
function(stream)
–> list(status,node,stream)
From input parameters, an anonymous function is defined. This function admits just one parameter, stream, with type streamParser
, and returns a three-field list:
status
"ok" or "fail"
node
With action
or error
function output, depending on the case
stream
With information about the input, after success or failure in recognition
# fail stream <- streamParserFromString("H") ( charInSetParser(isDigit)(stream) )[c("status","node")] # ok stream <- streamParserFromString("a") ( charInSetParser(isLetter)(stream) )[c("status","node")]
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