package ora.ch6;import java.io.InputStream;import java.io.InputStreamReader;import java.io.IOException;// A class that scans through an input// stream for strins without reading the// entire stream into a large string.public class InputHelper {    // Size of the input buffer    private static final int BUFFER_SIZE = 1024;    // The input buffer    private final char[] buffer = new char[BUFFER_SIZE];    // Number of characters left in the buffer    private int charsLeft;    // Index of the next character in the buffer    private int nextChar;    // InputStreamReader used to map to Unicode    private InputStreamReader reader;    // Constructs a helper to read a given stream    public InputHelper(InputStream is) {        reader = new InputStreamReader(is);    }        // Cleans up when no longer needed    public void dispose() {        if (reader != null) {            try {                reader.close();            } catch (IOException ex) {            }            reader = null;        }    }    // Looks for a given string in the input    // stream and positions the stream so that the    // next character read is one beyond the string.    // Returns true if the string was found, false if    // not (and the stream will have been completely read).    public boolean moveAfterString(String str) throws IOException {        char[] chars = str.toCharArray();        int count = chars.length;        char firstChar = chars[0];        char c = (char)0;        for (;;) {            if (c != firstChar && !findNext(firstChar)) {                // Reached the end of the input stream                return false;            }            boolean mismatch = false;            for (int i = 1; i < count; i++) {                c = getNext();                if (c != chars[i]) {                    mismatch = true;                    break;                }            }            if (!mismatch) {                return true;            }            // Mismatch. 'c' has the first mismatched            // character - start the loop again with            // that character. This is necessary because we            // could have found "wweb" while looking for "web"        }    }        // Gets the characters for a number, ignoring    // the grouping separator. The number starts at the    // current input position, but any leading non-numerics    // are skipped.    public String gatherNumber() throws IOException {        StringBuffer sb = new StringBuffer();        boolean gotNumeric = false;        for (;;) {            char c = getNext();                        // Skip until we find a digit.            boolean isDigit = Character.isDigit(c);            if (!gotNumeric && !isDigit) {                continue;            }            gotNumeric = true;            if (!isDigit) {                if (c == '.' || c == ',') {                    continue;                }                break;            }            sb.append(c);        }        return sb.toString();    }        // Gets the balance of the current line    // and returns it as a StringBuffer    public StringBuffer getRestOfLine() throws IOException {            StringBuffer sb = new StringBuffer();        char c;        for (;;) {            c = getNext();            if (c == '\n' || c == (char)0) {                break;            }            sb.append(c);        }        return sb;    }         // Gets the next character from the stream,    // returning (char)0 when all input has been read.    private char getNext() throws IOException {        if (charsLeft == 0) {            charsLeft = reader.read(buffer, 0, BUFFER_SIZE);            if (charsLeft < 0) {                return (char)0;            }            nextChar = 0;        }        charsLeft--;        return buffer[nextChar++];    }           // Finds the next instance of a given character in the    // input stream. The input stream is positioned after    // the located character. If EOF is reached without    // finding the character, false is returned.    private boolean findNext(char c) throws IOException {        for (;;) {            if (charsLeft == 0) {                charsLeft = reader.read(buffer, 0, BUFFER_SIZE);                if (charsLeft < 0) {                    return false;                }                nextChar = 0;            }            charsLeft--;            if (c == buffer[nextChar++]) {                return true;            }        }    }}