53 lines
1.2 KiB
Java
53 lines
1.2 KiB
Java
package scanner;
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import java.io.InputStream;
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import java.io.FilterInputStream;
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import java.io.IOException;
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/**
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* Replaces Lisp comments with newlines in an input stream.
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*/
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public class LispFilterStream extends FilterInputStream {
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private boolean inQuote;
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private int nextCharacter;
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public LispFilterStream(InputStream in) {
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super(in);
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inQuote = false;
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nextCharacter = 0;
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}
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@Override
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public int read() throws IOException {
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nextCharacter = super.read();
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if (haveEnteredComment()) {
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consumeAllBytesInComment();
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} else if (haveEncounteredStringBoundary()) {
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inQuote = (!inQuote);
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}
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return nextCharacter;
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}
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private void consumeAllBytesInComment() throws IOException {
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while (stillInComment()) {
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nextCharacter = super.read();
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}
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}
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private boolean stillInComment() {
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return (nextCharacter != '\n') && (nextCharacter != -1);
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}
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private boolean haveEnteredComment() {
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return (nextCharacter == ';') && (!inQuote);
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}
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private boolean haveEncounteredStringBoundary() {
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return nextCharacter == '\"';
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}
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}
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