Forlan Manual

The `Str` Module

Synopsis

signature STR structure Str :> STR

This module provides operations on Forlan strings, i.e., lists of Forlan symbols.

Interface

type str = Sym.sym list val possBeginsWithStr : (int * Lex.tok) list -> bool val inputFromLabToks : (int * Lex.tok) list -> str * (int * Lex.tok) list val fromString : string -> str val input : string -> str val toPP : str -> PP.pp val toString : str -> string val output : string * str -> unit val last : str -> Sym.sym val allButLast : str -> str val compare : str Sort.total_ordering val equal : str * str -> bool val alphabet : str -> Sym.sym Set.set val renameAlphabet : str * SymRel.sym_rel -> str val prefix : str * str -> bool val suffix : str * str -> bool val substr : str * str -> bool val power : str * int -> str val removePrefix : str * str -> str option val removeSuffix : str * str -> str option val jforlanValidate : string -> unit val jforlanPretty : string -> unit

Description

type str = Sym.sym list

The type of Forlan strings, i.e., lists of Forlan symbols.

In the concrete syntax for strings, the empty string is written as %, and a nonempty string [a1, ... an] is written as a1 ... an.

possBeginsWithStr lts

tests whether lts begins with a symbol or % (Lex.Perc), making it possible that a Forlan string could be parsed from lts.

inputFromLabToks lts

tries to input a Forlan string from lts, consuming as much of lts as possible, and returning the pair of that string and the rest of lts. Issues an error message if this can't be done.

fromString s

inputs a Forlan string from s.

input fil

inputs a Forlan string from the file named by fil.

toPP x

returns a pretty-printing expression for x.

toString x

pretty-prints x to a string.

output(fil, x)

pretty-prints x to the file named by fil.

last x

returns the last element of x. Raises Empty if x is empty.

allButLast x

returns all but the last element of x. Raises Empty if x is empty.

compare

is defined by:

  val compare = Set.compareList Sym.compare

This ordering first uses the length of strings (shorter is smaller), and then uses the lexicographic ordering on equal length strings.

equal(x, y)

tests whether x and y are equal.

alphabet x

returns the alphabet of x.

renameAlphabet(x, rel)

renames the alphabet of x using the bijection rel. Issues an error message if rel is not a bijection from a superset of the alphabet of x to some set.

prefix(x, y)

tests whether x is a prefix of y.

suffix(x, y)

tests whether x is a suffix of y.

substr(x, y)

tests whether x is a substring of y.

power(x, n)

raises x to the power n. Issues an error message if n is negative.

removePrefix(x, y)

If x is a prefix of y, then removePrefix returns SOME z, where z is the result of removing x from the beginning of y. Otherwise, removePrefix returns NONE.

removeSuffix(x, y)

If x is a suffix of y, then removeSuffix returns SOME z, where z is the result of removing x from the end of y. Otherwise, removeSuffix returns NONE.

jforlanValidate

is a low-level function used by JForlan. See the code for more information.

jforlanPretty