concatenation: One phrase then another

In qmrparser: Parser Combinator in R

One phrase then another

Description

Applies to the recognition a parsers sequence. Recognition will succeed as long as all of them succeed.

Usage

  
  concatenation(..., 
                action = function(s)   list(type="concatenation",value=s),
                error  = function(p,h) list(type="concatenation",pos=p ,h=h)) 
  

Arguments

...	list of parsers to be executed
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, parameter s from action gets a list with information about node from all parsers processed.

In case of failure, parameter h from error gets the value returned by the failing parser.

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("123Hello world")
( concatenation(numberNatural(),symbolic())(stream) )[c("status","node")]


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

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