Provided by: ocaml-nox_4.05.0-10ubuntu1_amd64 
NAME
Lexing - The run-time library for lexers generated by ocamllex.
Module
Module Lexing
Documentation
Module Lexing
: sig end
The run-time library for lexers generated by ocamllex .
=== Positions ===
type position = {
pos_fname : string ;
pos_lnum : int ;
pos_bol : int ;
pos_cnum : int ;
}
A value of type position describes a point in a source file. pos_fname is the file name; pos_lnum is the
line number; pos_bol is the offset of the beginning of the line (number of characters between the
beginning of the lexbuf and the beginning of the line); pos_cnum is the offset of the position (number of
characters between the beginning of the lexbuf and the position). The difference between pos_cnum and
pos_bol is the character offset within the line (i.e. the column number, assuming each character is one
column wide).
See the documentation of type lexbuf for information about how the lexing engine will manage positions.
val dummy_pos : position
A value of type position , guaranteed to be different from any valid position.
=== Lexer buffers ===
type lexbuf = {
refill_buff : lexbuf -> unit ;
mutable lex_buffer : bytes ;
mutable lex_buffer_len : int ;
mutable lex_abs_pos : int ;
mutable lex_start_pos : int ;
mutable lex_curr_pos : int ;
mutable lex_last_pos : int ;
mutable lex_last_action : int ;
mutable lex_eof_reached : bool ;
mutable lex_mem : int array ;
mutable lex_start_p : position ;
mutable lex_curr_p : position ;
}
The type of lexer buffers. A lexer buffer is the argument passed to the scanning functions defined by the
generated scanners. The lexer buffer holds the current state of the scanner, plus a function to refill
the buffer from the input.
At each token, the lexing engine will copy lex_curr_p to lex_start_p , then change the pos_cnum field of
lex_curr_p by updating it with the number of characters read since the start of the lexbuf . The other
fields are left unchanged by the lexing engine. In order to keep them accurate, they must be initialised
before the first use of the lexbuf, and updated by the relevant lexer actions (i.e. at each end of line
-- see also new_line ).
val from_channel : Pervasives.in_channel -> lexbuf
Create a lexer buffer on the given input channel. Lexing.from_channel inchan returns a lexer buffer
which reads from the input channel inchan , at the current reading position.
val from_string : string -> lexbuf
Create a lexer buffer which reads from the given string. Reading starts from the first character in the
string. An end-of-input condition is generated when the end of the string is reached.
val from_function : (bytes -> int -> int) -> lexbuf
Create a lexer buffer with the given function as its reading method. When the scanner needs more
characters, it will call the given function, giving it a byte sequence s and a byte count n . The
function should put n bytes or fewer in s , starting at index 0, and return the number of bytes provided.
A return value of 0 means end of input.
=== Functions for lexer semantic actions ===
=== The following functions can be called from the semantic actions of lexer definitions (the ML code
enclosed in braces that computes the value returned by lexing functions). They give access to the
character string matched by the regular expression associated with the semantic action. These functions
must be applied to the argument lexbuf, which, in the code generated by ocamllex, is bound to the lexer
buffer passed to the parsing function. ===
val lexeme : lexbuf -> string
Lexing.lexeme lexbuf returns the string matched by the regular expression.
val lexeme_char : lexbuf -> int -> char
Lexing.lexeme_char lexbuf i returns character number i in the matched string.
val lexeme_start : lexbuf -> int
Lexing.lexeme_start lexbuf returns the offset in the input stream of the first character of the matched
string. The first character of the stream has offset 0.
val lexeme_end : lexbuf -> int
Lexing.lexeme_end lexbuf returns the offset in the input stream of the character following the last
character of the matched string. The first character of the stream has offset 0.
val lexeme_start_p : lexbuf -> position
Like lexeme_start , but return a complete position instead of an offset.
val lexeme_end_p : lexbuf -> position
Like lexeme_end , but return a complete position instead of an offset.
val new_line : lexbuf -> unit
Update the lex_curr_p field of the lexbuf to reflect the start of a new line. You can call this function
in the semantic action of the rule that matches the end-of-line character.
Since 3.11.0
=== Miscellaneous functions ===
val flush_input : lexbuf -> unit
Discard the contents of the buffer and reset the current position to 0. The next use of the lexbuf will
trigger a refill.