# Module Scanf.Scanning

    module Scanning: sig .. end

###### Scanning buffers

    type scanbuf

The type of scanning buffers. A scanning buffer is the source from which a formatted input function gets characters. The scanning buffer holds the current state of the scan, plus a function to get the next char from the input, and a token buffer to store the string matched so far.

Note: a scan may often require to examine one character in advance; when this ``lookahead'' character does not belong to the token read, it is stored back in the scanning buffer and becomes the next character read.

    val stdib : scanbuf

The scanning buffer reading from `stdin`. `stdib` is equivalent to `Scanning.from_channel stdin`.

Note: when input is read interactively from `stdin`, the newline character that triggers the evaluation is incorporated in the input; thus, scanning specifications must properly skip this character (simply add a `'\n'` as the last character of the format string).

    val from_string : string -> scanbuf

`Scanning.from_string s` returns a scanning buffer which reads from the given string. Reading starts from the first character in the string. The end-of-input condition is set when the end of the string is reached.

    val from_file : string -> scanbuf

Bufferized file reading in text mode. The efficient and usual way to scan text mode files (in effect, `from_file` returns a scanning buffer that reads characters in large chunks, rather than one character at a time as buffers returned by `from_channel` do). `Scanning.from_file fname` returns a scanning buffer which reads from the given file `fname` in text mode.

    val from_file_bin : string -> scanbuf

Bufferized file reading in binary mode.

    val from_function : (unit -> char) -> scanbuf

`Scanning.from_function f` returns a scanning buffer with the given function as its reading method.

When scanning needs one more character, the given function is called.

When the function has no more character to provide, it must signal an end-of-input condition by raising the exception `End_of_file`.

    val from_channel : in_channel -> scanbuf

`Scanning.from_channel ic` returns a scanning buffer which reads from the input channel `ic`, starting at the current reading position.

    val end_of_input : scanbuf -> bool

`Scanning.end_of_input ib` tests the end-of-input condition of the given scanning buffer.

    val beginning_of_input : scanbuf -> bool

`Scanning.beginning_of_input ib` tests the beginning of input condition of the given scanning buffer.

    val name_of_input : scanbuf -> string

`Scanning.file_name_of_input ib` returns the name of the character source for the scanning buffer `ib`.