separator: Generic word separator token.

In qmrparser: Parser Combinator in R

Generic word separator token.

Description

Recognises a white character sequence, with comma or semicolon optionally inserted in the sequence. Empty sequences are not allowed.

Usage

separator(action = function(s) list(type="separator",value=s) , 
          error  = function(p) list(type="separator",pos  =p) ) 

Arguments

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 streamParser obtained with streamParserPosition is passed as parameter to this function

Details

A character is considered a white character when function isWhitespace returns TRUE

Value

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

Note

PC-Axis has accepted the delimiters comma, space, semicolon, tabulator.

Examples

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

# ok 
stream  <- streamParserFromString(" ")
( separator()(stream) )[c("status","node")]


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

# fail 
stream  <- streamParserFromString("")
( separator()(stream) )[c("status","node")]

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