r_grammar.pl -- R parser primitives

See also

- https://cran.r-project.org/doc/manuals/r-release/R-lang.html#Parser

 r_tokens(-Tokens:list)// is nondet

Get R tokens in a non-greedy fashion. Backtracking extracts more tokens from the input. See r_token/1 for getting a single token.

 r_identifier(+Atom) is semidet

True if Atom is a valid R identifier name.

 r_token(-Token)// is semidet

Get an R token from the input. Defined tokens are:

number(FloatOrInt)

Used for numerical constants.

complex(FloatOrInt)

Used for <number>i.

string(String)

Used for quoted strings.

identifier(Atom)

General identifier (includes function names)

constant(Atom)

Reserved constants (e.g., NULL, NA, ...)

logical(Boolean)

Used for TRUE and FALSE

keyword(Atom)

Used for if, else, etc.

infix(Atom)

Used for %...% infix operators

op(Atom)

Used for +, -, *, etc.

punct(Atom)

Used for the braces {[()]} and the comma (,)

comment(String)

Used for # Comment lines.

 r_number(-Number)// is semidet[private]

 r_string(-String)// is semidet[private]

 r_identifier(-Identifier)

Recognise an R identifier. This includes reserved terms and constants. These are filtered later.

 identifier_token(+Id, -Token) is det[private]

 r_infix(-Infix)//[private]

 r_operator(-Op)//[private]