scanner.h

来自「书名:C语言科学与艺术,以前交钱下载的」· C头文件 代码 · 共 76 行

/*
 * File: scanner.h
 * ---------------
 * This file is the interface to a package that divides
 * a line into individual "tokens".  A token is defined
 * to be either
 *
 * 1. a string of consecutive letters and digits representing
 *    a word, or
 *
 * 2. a one-character string representing a separator
 *    character, such as a space or a punctuation mark.
 *
 * To use this package, you must first call
 *
 *        InitScanner(line);
 *
 * where line is the string (typically a line returned by
 * GetLine) that is to be divided into tokens.  To retrieve
 * each token in turn, you call
 *
 *        token = GetNextToken();
 *
 * When the last token has been read, the predicate function
 * AtEndOfLine returns TRUE, so that the loop structure
 *
 *        while (!AtEndOfLine()) {
 *            token = GetNextToken();
 *            . . . process the token . . .
 *        }
 *
 * serves as an idiom for processing each token on the line.
 *
 * Further details for each function are given in the
 * individual descriptions below.
 */

#ifndef _scanner_h
#define _scanner_h

#include "genlib.h"

/*
 * Function: InitScanner
 * Usage: InitScanner(line);
 * -------------------------
 * This function initializes the scanner and sets it up so that
 * it reads tokens from line.  After InitScanner has been called,
 * the first call to GetNextToken will return the first token
 * on the line, the next call will return the second token,
 * and so on.
 */

void InitScanner(string line);

/*
 * Function: GetNextToken
 * Usage: word = GetNextToken();
 * -----------------------------
 * This function returns the next token on the line.
 */

string GetNextToken(void);

/*
 * Function: AtEndOfLine
 * Usage: if (AtEndOfLine()) . . .
 * -------------------------------
 * This function returns TRUE when the scanner has reached
 * the end of the line.
 */

bool AtEndOfLine(void);

#endif