repetition1N: Repeats a parser, at least once.

In qmrparser: Parser Combinator in R

Repeats a parser, at least once.

Description

Repeats a parser application indefinitely while it is successful. It must succeed at least once.

Usage

  
  repetition1N(rpa, 
               action = function(s)   list(type="repetition1N",value=s  ),
               error  = function(p,h) list(type="repetition1N",pos=p,h=h))

Arguments

rpa	parse to be applied iteratively
action	Function to be executed if recognition succeeds. It takes as input parameters information derived from parsers involved as parameters
error	Function to be executed if recognition does not succeed. I takes two parameters: p with position where parser, streamParser, starts its recognition, obtained with streamParserPosition h with information obtained from parsers involved as parameters, normally related with failure(s) position in component parsers. Its information depends on how parser involved as parameters are combined and on the error definition in these parsers.

Details

In case of success, action gets a list with information about the node returned by the applied parser. List length equals the number of successful repetitions.

In case of failure, parameter h from error gets error information returned by the first attempt of parser application.

Value

Anonymous functions, returning a list.

function(stream) –> list(status,node,stream)

From these input parameters, an anonymous function is constructed. This function admits just one parameter, stream, with streamParser class, 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

Examples

# ok
stream  <- streamParserFromString("Hello world")
( repetition1N(symbolic())(stream) )[c("status","node")]


# fail
stream  <- streamParserFromString("123 Hello world")
( repetition1N(symbolic())(stream) )[c("status","node")]

qmrparser documentation built on April 24, 2022, 1:05 a.m.