/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2007 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
package alterrs.asm.signature;

/**
 * A type signature parser to make a signature visitor visit an existing
 * signature.
 * 
 * @author Thomas Hallgren
 * @author Eric Bruneton
 */
public class SignatureReader {

	/**
	 * The signature to be read.
	 */
	private final String signature;

	/**
	 * Constructs a {@link SignatureReader} for the given signature.
	 * 
	 * @param signature
	 *            A <i>ClassSignature</i>, <i>MethodTypeSignature</i>, or
	 *            <i>FieldTypeSignature</i>.
	 */
	public SignatureReader(final String signature) {
		this.signature = signature;
	}

	/**
	 * Makes the given visitor visit the signature of this
	 * {@link SignatureReader}. This signature is the one specified in the
	 * constructor (see {@link #SignatureReader(String) SignatureReader}). This
	 * method is intended to be called on a {@link SignatureReader} that was
	 * created using a <i>ClassSignature</i> (such as the <code>signature</code>
	 * parameter of the {@link alterrs.asm.ClassVisitor#visit
	 * ClassVisitor.visit} method) or a <i>MethodTypeSignature</i> (such as the
	 * <code>signature</code> parameter of the
	 * {@link alterrs.asm.ClassVisitor#visitMethod ClassVisitor.visitMethod}
	 * method).
	 * 
	 * @param v
	 *            the visitor that must visit this signature.
	 */
	public void accept(final SignatureVisitor v) {
		String signature = this.signature;
		int len = signature.length();
		int pos;
		char c;

		if (signature.charAt(0) == '<') {
			pos = 2;
			do {
				int end = signature.indexOf(':', pos);
				v.visitFormalTypeParameter(signature.substring(pos - 1, end));
				pos = end + 1;

				c = signature.charAt(pos);
				if (c == 'L' || c == '[' || c == 'T') {
					pos = parseType(signature, pos, v.visitClassBound());
				}

				while ((c = signature.charAt(pos++)) == ':') {
					pos = parseType(signature, pos, v.visitInterfaceBound());
				}
			} while (c != '>');
		} else {
			pos = 0;
		}

		if (signature.charAt(pos) == '(') {
			pos++;
			while (signature.charAt(pos) != ')') {
				pos = parseType(signature, pos, v.visitParameterType());
			}
			pos = parseType(signature, pos + 1, v.visitReturnType());
			while (pos < len) {
				pos = parseType(signature, pos + 1, v.visitExceptionType());
			}
		} else {
			pos = parseType(signature, pos, v.visitSuperclass());
			while (pos < len) {
				pos = parseType(signature, pos, v.visitInterface());
			}
		}
	}

	/**
	 * Makes the given visitor visit the signature of this
	 * {@link SignatureReader}. This signature is the one specified in the
	 * constructor (see {@link #SignatureReader(String) SignatureReader}). This
	 * method is intended to be called on a {@link SignatureReader} that was
	 * created using a <i>FieldTypeSignature</i>, such as the
	 * <code>signature</code> parameter of the
	 * {@link alterrs.asm.ClassVisitor#visitField ClassVisitor.visitField} or
	 * {@link alterrs.asm.MethodVisitor#visitLocalVariable
	 * MethodVisitor.visitLocalVariable} methods.
	 * 
	 * @param v
	 *            the visitor that must visit this signature.
	 */
	public void acceptType(final SignatureVisitor v) {
		parseType(this.signature, 0, v);
	}

	/**
	 * Parses a field type signature and makes the given visitor visit it.
	 * 
	 * @param signature
	 *            a string containing the signature that must be parsed.
	 * @param pos
	 *            index of the first character of the signature to parsed.
	 * @param v
	 *            the visitor that must visit this signature.
	 * @return the index of the first character after the parsed signature.
	 */
	private static int parseType(final String signature, int pos,
			final SignatureVisitor v) {
		char c;
		int start, end;
		boolean visited, inner;
		String name;

		switch (c = signature.charAt(pos++)) {
		case 'Z':
		case 'C':
		case 'B':
		case 'S':
		case 'I':
		case 'F':
		case 'J':
		case 'D':
		case 'V':
			v.visitBaseType(c);
			return pos;

		case '[':
			return parseType(signature, pos, v.visitArrayType());

		case 'T':
			end = signature.indexOf(';', pos);
			v.visitTypeVariable(signature.substring(pos, end));
			return end + 1;

		default: // case 'L':
			start = pos;
			visited = false;
			inner = false;
			for (;;) {
				switch (c = signature.charAt(pos++)) {
				case '.':
				case ';':
					if (!visited) {
						name = signature.substring(start, pos - 1);
						if (inner) {
							v.visitInnerClassType(name);
						} else {
							v.visitClassType(name);
						}
					}
					if (c == ';') {
						v.visitEnd();
						return pos;
					}
					start = pos;
					visited = false;
					inner = true;
					break;

				case '<':
					name = signature.substring(start, pos - 1);
					if (inner) {
						v.visitInnerClassType(name);
					} else {
						v.visitClassType(name);
					}
					visited = true;
					top: for (;;) {
						switch (c = signature.charAt(pos)) {
						case '>':
							break top;
						case '*':
							++pos;
							v.visitTypeArgument();
							break;
						case '+':
						case '-':
							pos = parseType(signature, pos + 1,
									v.visitTypeArgument(c));
							break;
						default:
							pos = parseType(signature, pos,
									v.visitTypeArgument('='));
							break;
						}
					}
				}
			}
		}
	}
}
