/*
 * Anarres C Preprocessor
 * Copyright (c) 2007-2008, Shevek
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied.  See the License for the specific language governing
 * permissions and limitations under the License.
 */

package org.anarres.cpp;

import java.io.Reader;
import java.io.PushbackReader;
import java.io.IOException;

/* pp */ class JoinReader /* extends Reader */ {
	private Reader	in;

	private PreprocessorListener	listener;
	private LexerSource				source;
	private boolean	trigraphs;
	private boolean	warnings;

	private int		newlines;
	private boolean	flushnl;
	private int[]	unget;
	private int		uptr;

	public JoinReader(Reader in, boolean trigraphs) {
		this.in = in;
		this.trigraphs = trigraphs;
		this.newlines = 0;
		this.flushnl = false;
		this.unget = new int[2];
		this.uptr = 0;
	}

	public JoinReader(Reader in) {
		this(in, false);
	}

	public void setTrigraphs(boolean enable, boolean warnings) {
		this.trigraphs = enable;
		this.warnings = warnings;
	}

	/* pp */ void init(Preprocessor pp, LexerSource s) {
		this.listener = pp.getListener();
		this.source = s;
		setTrigraphs(pp.getFeature(Feature.TRIGRAPHS),
						pp.getWarning(Warning.TRIGRAPHS));
	}

	private int __read() throws IOException {
		if (uptr > 0)
			return unget[--uptr];
		return in.read();
	}

	private void _unread(int c) {
		if (c != -1)
			unget[uptr++] = c;
		assert uptr <= unget.length :
				"JoinReader ungets too many characters";
	}

	protected void warning(String msg)
						throws LexerException {
		if (source != null)
			source.warning(msg);
		else
			throw new LexerException(msg);
	}

	private char trigraph(char raw, char repl)
						throws IOException, LexerException {
		if (trigraphs) {
			if (warnings)
				warning("trigraph ??" + raw + " converted to " + repl);
			return repl;
		}
		else {
			if (warnings)
				warning("trigraph ??" + raw + " ignored");
			_unread(raw);
			_unread('?');
			return '?';
		}
	}

	private int _read()
						throws IOException, LexerException {
		int	c = __read();
		if (c == '?' && (trigraphs || warnings)) {
			int d = __read();
			if (d == '?') {
				int	e = __read();
				switch (e) {
					case '(': return trigraph('(', '[');
					case ')': return trigraph(')', ']');
					case '<': return trigraph('<', '{');
					case '>': return trigraph('>', '}');
					case '=': return trigraph('=', '#');
					case '/': return trigraph('/', '\\');
					case '\'': return trigraph('\'', '^');
					case '!': return trigraph('!', '|');
					case '-': return trigraph('-', '~');
				}
				_unread(e);
			}
			_unread(d);
		}
		return c;
	}

	public int read()
						throws IOException, LexerException {
		if (flushnl) {
			if (newlines > 0) {
				newlines--;
				return '\n';
			}
			flushnl = false;
		}

		for (;;) {
			int	c = _read();
			switch (c) {
				case '\\':
					int	d = _read();
					switch (d) {
						case '\n':
							newlines++;
							continue;
						case '\r':
							newlines++;
							int	e = _read();
							if (e != '\n')
								_unread(e);
							continue;
						default:
							_unread(d);
							return c;
					}
				case '\r':
				case '\n':
				case '\u2028':
				case '\u2029':
				case '\u000B':
				case '\u000C':
				case '\u0085':
					flushnl = true;
					return c;
				case -1:
					if (newlines > 0) {
						newlines--;
						return '\n';
					}
				default:
					return c;
			}
		}
	}

	public int read(char cbuf[], int off, int len)
						throws IOException, LexerException {
		for (int i = 0; i < len; i++) {
			int	ch = read();
			if (ch == -1)
				return i;
			cbuf[off + i] = (char)ch;
		}
		return len;
	}

	public void close()
						throws IOException {
		in.close();
	}

	public String toString() {
		return "JoinReader(nl=" + newlines + ")";
	}

/*
	public static void main(String[] args) throws IOException {
		FileReader		f = new FileReader(new File(args[0]));
		BufferedReader	b = new BufferedReader(f);
		JoinReader		r = new JoinReader(b);
		BufferedWriter	w = new BufferedWriter(
				new java.io.OutputStreamWriter(System.out)
					);
		int				c;
		while ((c = r.read()) != -1) {
			w.write((char)c);
		}
		w.close();
	}
*/

}