qmrparser (version 0.1.6)

whitespace: White sequence token.

Description

Recognises a white character sequence (this sequence may be empty).

Usage

whitespace(action = function(s) list(type="white",value=s), 
             error  = function(p) list(type="white",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

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

Details

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

Examples

# NOT RUN {
# ok
stream  <- streamParserFromString("Hello world")
( whitespace()(stream) )[c("status","node")]

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

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

# }