An R6 class for manipulating/interrogating a stream of tokens.

Source: R/TokenStream.R

An R6 class for manipulating/interrogating a stream of tokens.

An R6 class for manipulating/interrogating a stream of tokens.

Public fields

named_values

the original tokens

position

current stream position Initialise a stream

Methods

Public methods

Method new()

Usage

TokenStream$new(named_values)

Arguments

named_values

named vector of values Reset stream to the given absolute position.

Method reset()

Usage

TokenStream$reset(position = 1L)

Arguments

position

absolute position in stream. Default: 1 i.e. the start Throw an error if a read is not within range

Method assert_within_range()

Usage

TokenStream$assert_within_range(start, n)

Arguments

start, n

start position and number of values to read Check if a read is not within range

Method check_within_range()

Usage

TokenStream$check_within_range(start, n)

Arguments

start, n

start position and number of values to read

Returns

logical TRUE if values are within range of data Check the next names match the name sequence specified

Method check_name_seq()

Usage

TokenStream$check_name_seq(name_seq)

Arguments

name_seq

Expected sequence of names Assert the next names match the name sequence specified

Method assert_name_seq()

Usage

TokenStream$assert_name_seq(name_seq)

Arguments

name_seq

Expected sequence of names Check the next name is one of the valid names specified

Method check_name()

Usage

TokenStream$check_name(valid_names)

Arguments

valid_names

Valid names Assert the next name is one of the valid names specified

Method assert_name()

Usage

TokenStream$assert_name(valid_names)

Arguments

valid_names

Valid names Check the next values match the value sequence specified

Method check_value_seq()

Usage

TokenStream$check_value_seq(value_seq)

Arguments

value_seq

Expected sequence of values Assert the next values match the value sequence specified

Method assert_value_seq()

Usage

TokenStream$assert_value_seq(value_seq)

Arguments

value_seq

Expected sequence of values Check the next value is one of the valid values specified

Method check_value()

Usage

TokenStream$check_value(valid_values)

Arguments

valid_values

Valid values Assert the next value is one of the valid values specified

Method assert_value()

Usage

TokenStream$assert_value(valid_values)

Arguments

valid_values

Valid values Advance the stream

Method advance()

Usage

TokenStream$advance(n)

Arguments

n

number of tokens by which to advance the stream. May be negative. New position must be within range of the data Read n named values from the given positionReturns values but does not advance stream position

Method read()

Usage

TokenStream$read(n, offset = 0)

Arguments

n

number of values to read

offset

offset from given position

Returns

named values at this position Read n names from the given position

Returns values but does not advance stream position

Method read_names()

Usage

TokenStream$read_names(n, offset = 0)

Arguments

n

number of values to read

offset

offset from given position

Returns

names at this position Read n values from the given position

Returns values but does not advance stream position

Method read_values()

Usage

TokenStream$read_values(n, offset = 0)

Arguments

n

number of values to read

offset

offset from given position

Returns

values at this position Consume n tokens from the given position i.e. read and advance the stream

Returns values and advances stream position.

Method consume()

Usage

TokenStream$consume(n)

Arguments

n

number of values to read

Returns

values starting at this position

Method end_of_stream()

has end of stream been reached? Read tokens while some expression matches

Returns values but does not advance stream position

Usage

TokenStream$end_of_stream()

Method read_while()

Usage

TokenStream$read_while(name = NULL, value = NULL, combine = "or")

Arguments

name, value

the boundary of the consumption. if both name and value are specified, then combine indicates how to logically define the combination

combine

logical operator value values: and, or Consume tokens while some expression matchesReturns values and advances stream position.

Method consume_while()

Usage

TokenStream$consume_while(name = NULL, value = NULL, combine = "or")

Arguments

name, value

the boundary of the consumption. if both name and value are specified, then combine indicates how to logically define the combination

combine

logical operator value values: and, or Read until some expression matchesReturns values but does not advance stream position

Method read_until()

Usage

TokenStream$read_until(
  name = NULL,
  value = NULL,
  combine = "or",
  inclusive = TRUE
)

Arguments

name, value

the boundary of the consumption. if both name and value are specified, then combine indicates how to logically define the combination

combine

logical operator value values: and, or

inclusive

should the end-point be included in the returned results? Default: TRUE. If FALSE, then the end-point is not returned, and the stream position is set to *before* this end-point Consume until some expression matchesReturns values and advances stream position.

Method consume_until()

Usage

TokenStream$consume_until(
  name = NULL,
  value = NULL,
  combine = "or",
  inclusive = TRUE
)

Arguments

name, value

the boundary of the consumption. if both name and value are specified, then combine indicates how to logically define the combination

combine

logical operator value values: and, or

inclusive

should the end-point be included in the returned results? Default: TRUE. If FALSE, then the end-point is not returned, and the stream position is set to *before* this end-point Print current state

Method print()

Usage

TokenStream$print(n = 5)

Arguments

n

number of elements to print

Method clone()

The objects of this class are cloneable with this method.

Usage

TokenStream$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.