Batteries user guide : Batteries.Genlex

# Module Batteries.Genlex

    module Genlex: BatGenlex

    type token = Genlex.token =

`|` | `Kwd of `string``
`|` | `Ident of `string``
`|` | `Int of `int``
`|` | `Float of `float``
`|` | `String of `string``
`|` | `Char of `char``

The type of tokens. The lexical classes are: `Int` and `Float` for integer and floating-point numbers; `String` for string literals, enclosed in double quotes; `Char` for character literals, enclosed in single quotes; `Ident` for identifiers (either sequences of letters, digits, underscores and quotes, or sequences of ``operator characters'' such as `+`, `*`, etc); and `Kwd` for keywords (either identifiers or single ``special characters'' such as `(`, `}`, etc).

    val make_lexer : string list -> char Stream.t -> token Stream.t

Construct the lexer function. The first argument is the list of keywords. An identifier `s` is returned as `Kwd s` if `s` belongs to this list, and as `Ident s` otherwise. A special character `s` is returned as `Kwd s` if `s` belongs to this list, and cause a lexical error (exception `Parse_error`) otherwise. Blanks and newlines are skipped. Comments delimited by `(*` and `*)` are skipped as well, and can be nested.

    type lexer_error =

`|` | `IllegalCharacter of `char``
`|` | `NotReallyAChar`
`|` | `NotReallyAnEscape`
`|` | `EndOfStream`

    exception LexerError of lexer_error * int

    type t

A lexer

    val of_list : string list -> t

Create a lexer from a list of keywords

    val to_stream_filter : t -> char Stream.t -> token Stream.t

Apply the lexer to a stream.

    val to_enum_filter : t -> char BatEnum.t -> token BatEnum.t

Apply the lexer to an enum.

    val to_lazy_list_filter : t -> char BatLazyList.t -> token BatLazyList.t

Apply the lexer to a lazy list.

    val string_of_token : token -> string

###### Extending to other languages

    module Languages: sig .. end