package batteries

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.

The scanning buffer reading from stdin. stdib is equivalent to Scanning.from_input 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).

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.

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.

Bufferized file reading in binary mode.

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.

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

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

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

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

@obsolete use from_input