Module Cf_lexer

module Cf_lexer: sig .. end

Lexical analysis with functional composition of regular grammars.

Overview

This module implements functional parsers of the type defined in the Cf_parser.X module using lazy deterministic finite automata. Ordinary characters are the symbol type.

Note: functions for converting regular expression strings into lexer expressions are not provided.

Classes

The class of cursors used by lazy DFA parser. It inherits from the basic parser and defines a new method for handling errors.

class cursor : int -> object .. end

Types

type expr_t

The type of lexer expressions.

type (#cursor, 'a) rule_t

The type of lexer rules.

type (#cursor, 'a) t = (#cursor as 'b, char, 'a) Cf_parser.X.t

The type of lexical analyzers, which are defined as parsers that use input symbols of type char.

Functions

module Op: sig .. end

Open this module to bring the operator functions into the current scope.

val nil : expr_t

The lexer expression that recognizes the empty input sequence, i.e. epsilon.

val create : (#cursor as 'a, 'b) rule_t -> ('a, 'b) t

Use create ?xf r to compose a lexical analyzer from the rule r.

type counter_t = {

`c_pos : int;`	`(*`	`The character index (counts from zero).`	`*)`
`c_row : int;`	`(*`	`The column number (counts from zero).`	`*)`
`c_col : int;`	`(*`	`The row number (counts from zero).`	`*)`

}

A record used by the line_cursor class defined below that indicates the character index, row and column in the input stream associated with a cursor position.

val counter_zero : counter_t

The initial value of a cursor position counter.

class line_cursor : ?c:counter_t -> string -> object .. end

A class derived from Cf_parser.cursor that intercepts newline characters to track the row and column of a cursor position.

exception Error of counter_t

The exception raised by the raise_exn exception handler function below.

val raise_exn : int -> (char * #line_cursor) Cf_seq.t -> exn

An optional exception handler function for use in streams woven with cursors of the #line_cursor class type. When the exception handler is called, the exception returned is constructed as Error c#counter.