NAME¶

smllex - the lexical analyzer generator for SML#

SYNOPSIS¶

smllex [-o file] filename ...

DESCRIPTION¶

SMLLex is a lexical analyzer generator in the style of ML-Lex. It accepts input files designed for ML-Lex. Generated programs can be compiled by the SML# compiler. They are compatible to those of ML-Lex with a few exceptions.

When multiple input files are given, each input file is separately read and yields a separate program. By default, the output file name is obtained by appending .sml suffix to the input file name.

To compile the generated program with SML#, an interface file (.smi file) is needed. See EXAMPLES for details.

EXAMPLES¶

The following is a minimal example of an input file ex.lex:

type lexresult = bool option
fun eof () = NONE
%%
%structure ExampleLex
%%
"T" => (SOME true);
"F" => (SOME false);

By applying this file to smllex,

smllex ex.lex

you obtains a program named ex.lex.sml. To compile it, you need to create the following ex.lex.smi file by yourself:

_require "basis.smi"
structure ExampleLex =
struct


  exception LexError


  val makeLexer : (int -> string) -> unit -> bool option
end

When your .lex file has an %arg, directive, for example,

type lexresult = bool option
fun eof {inverse} = NONE
%%
%structure Example2Lex
%arg ({inverse});
%%
"T" => (SOME (if inverse then false else true));
"F" => (SOME (if inverse then true else false));

the generated makeLexer function takes an additional argument:

_require "basis.smi"
structure Example2Lex =
struct


  exception LexError


  val makeLexer : (int -> string) -> {inverse : bool}


                  -> unit -> bool option
end

HISTORY¶

SMLLex is a derivative of ML-Lex, which is originally developed by Andrew W. Appel, James S. Mattson, and David R. Tarditi.

Major changes from the orginal ML-Lex includes the following:

• The command line option -o is added.
• The character position starts with 0, not 2.
• The generated program does not use Unsafe features of SML/NJ.

SEE ALSO¶

smlyacc(1)
A lexical analyzer generator for Standard ML, available at https://www.smlnj.org/doc/ML-Lex/manual.html
SML# Document, available at https://www.pllab.riec.tohoku.ac.jp/smlsharp/docs/