bundles/org.eclipse.uomo.util/src/main/java/org/eclipse/uomo/util/numbers/NumberValidator.java

/**
 * Copyright (c) 2005, 2013, Werner Keil and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Grahame Grieve - initial API and implementation
 */
package org.eclipse.uomo.util.numbers;

import static org.eclipse.uomo.util.numbers.UOMoNumberFormatException.Kind.*;

import java.math.BigDecimal;

import org.eclipse.uomo.util.internal.Messages;

/**
 * Double: a mantissa followed, optionally, by the character "E" or "e",
 * followed by an exponent. The exponent must be an integer. The mantissa must
 * be a decimal number. The representations for exponent and mantissa must
 * follow the lexical rules for integer and decimal. If the "E" or "e" and the
 * following exponent are omitted, an exponent value of 0 is assumed.
 * 
 * The special values positive and negative zero, positive and negative infinity
 * and not-a-number have lexical representations 0, -0, INF, -INF and NaN,
 * respectively.
 * 
 * Decimal: decimal has a lexical representation consisting of a finite-length
 * sequence of decimal digits (#x30-#x39) separated by a period as a decimal
 * indicator. An optional leading sign is allowed. If the sign is omitted, "+"
 * is assumed. Leading and trailing zeroes are optional. If the fractional part
 * is zero, the period and following zero(es) can be omitted.
 * 
 * @author Grahame Grieve
 */

class NumberValidator {

	private String source;
	private int cursor;
	private DecimalFormatOptions options;

	private String whole;
	private String decimals;
	private String exponent;

	/**
	 * @param source
	 * @param cursor
	 * @param options
	 */
	protected NumberValidator(String source, DecimalFormatOptions options) {
		super();
		this.source = source;
		this.cursor = 0;
		this.options = options;
	}

	private boolean optionsBanExponent() {
		return options != null && options instanceof RealFormatOptions
				&& ((RealFormatOptions) options).getExponent() != null
				&& !((RealFormatOptions) options).getExponent().booleanValue();
	}

	private boolean optionsRequireExponent() {
		return options != null && options instanceof RealFormatOptions
				&& ((RealFormatOptions) options).getExponent() != null
				&& ((RealFormatOptions) options).getExponent().booleanValue();
	}

	private boolean optionsAllowSpecial() {
		return options != null && options instanceof RealFormatOptions
				&& ((RealFormatOptions) options).isAllowSpecial();
	}

	private boolean more() {
		return cursor < source.length();
	}

	private char peek() {
		if (!more())
			return ' ';
		else
			return source.charAt(cursor);
	}

	private char next() {
		char ch = peek();
		cursor++;
		return ch;
	}

	private String pos() {
		return Integer.toString(cursor);
	}

	private void start() throws UOMoNumberFormatException {
		if (source == null || source.equals("")) //$NON-NLS-1$
			throw new UOMoNumberFormatException(TEXT_FORMAT,
					Messages.NumberValidator_Number_empty);

		whole = null;
		decimals = null;
		exponent = null;
	}

	public long parseInteger() throws UOMoNumberFormatException {
		validateInteger();
		try {
			return Long.parseLong(whole);
		} catch (Exception e) {
			// can get to here if the number is too big
			throw new UOMoNumberFormatException(SIZE, e.getMessage());
		}
	}

	public BigDecimal parseDecimal() throws UOMoNumberFormatException {
		validateDecimal();
		try {
			return new BigDecimal(whole
					+ (decimals == null ? "" : Messages.NumberValidator_DOT + decimals)); //$NON-NLS-1$
		} catch (NumberFormatException e) {
			// can get to here if the number is too big (for example,
			// 1.0e10000000000000000000000000000000000000000000000000000000)
			throw new UOMoNumberFormatException(SIZE, e.getMessage());
		}
	}

	public BigDecimal parseReal() throws UOMoNumberFormatException {
		validateReal();
		if (whole.equals(NaN))
			throw new UOMoNumberFormatException(NaN, Messages.NumberValidator_Value_not_a_number);
		else if (whole.equals(Messages.NumberValidator_INF) || whole.equals(Messages.NumberValidator_plusINF))
			throw new UOMoNumberFormatException(PINF, Messages.NumberValidator_Value_Infinity);
		else if (whole.equals(Messages.NumberValidator_minusINF))
			throw new UOMoNumberFormatException(NINF,
					Messages.NumberValidator_Value_negative_Infinity);
		else
			try {
				return new BigDecimal(whole
						+ (decimals == null ? "" : "." + decimals) //$NON-NLS-1$
						+ (exponent == null ? "" : Messages.NumberValidator_E + exponent)); //$NON-NLS-1$
			} catch (NumberFormatException e) {
				throw new UOMoNumberFormatException(SIZE,
						e.getLocalizedMessage());
			}
	}

	public void validateInteger() throws UOMoNumberFormatException {
		start();
		whole = processInteger(true, false, Messages.NumberValidator_an_Integer);
		if (more())
			throw new UOMoNumberFormatException(TEXT_FORMAT,
					Messages.NumberValidator_Unexpected_Content_after_Parsing_Int + peek() + "' at character " + pos() //$NON-NLS-2$
							+ " after parsing integer"); //$NON-NLS-1$
	}

	public void validateReal() throws UOMoNumberFormatException {
		start();

		processDecimal();
		if (more()) {
			if (peek() != 'e' && peek() != 'E')
				throw new UOMoNumberFormatException(TEXT_FORMAT,
						Messages.NumberValidator_Unexpected_Content_at_Char_expecting_E + peek() + "' at character " //$NON-NLS-2$
								+ pos() + " expecting e or E"); //$NON-NLS-1$
			if (optionsBanExponent())
				throw new UOMoNumberFormatException(RULE,
						Messages.NumberValidator_Exponent_Format_not_allowed_in_Context);
			next();
			exponent = processInteger(true, false, Messages.NumberValidator_an_Exponent);
			if (more()) {
				throw new UOMoNumberFormatException(TEXT_FORMAT,
						Messages.NumberValidator_Unexpected_Content_after_Parsing_Exponent + peek() + "' at character " //$NON-NLS-2$
								+ pos() + " after parsing exponent"); //$NON-NLS-1$
			}
		} else if (optionsRequireExponent())
			throw new UOMoNumberFormatException(
					UOMoNumberFormatException.Kind.RULE,
					Messages.NumberValidator_Exponent_Format_required_in_Context);

		checkDigits();
	}

	public void validateDecimal() throws UOMoNumberFormatException {
		start();

		processDecimal();
		if (more())
			throw new UOMoNumberFormatException(TEXT_FORMAT,
					Messages.NumberValidator_Unexpected_Content_after_Parsing_Decimal + peek() + "' at character " + pos() //$NON-NLS-2$
							+ " after parsing decimal"); //$NON-NLS-1$

		checkDigits();
	}

	private void checkDigits() throws UOMoNumberFormatException {
		if (options != null) {
			if (options.getFractionDigits() != DecimalFormatOptions.ANY_DIGITS
					&& decimals != null) {
				if (decimals.length() > options.getFractionDigits())
					throw new UOMoNumberFormatException(
							UOMoNumberFormatException.Kind.RULE,
							Messages.NumberValidator_Only_Digits_after_Decimal_allowed_but_found
									+ Integer.toString(options
											.getFractionDigits())
									+ " digits after the decimal are allowed, but found " //$NON-NLS-1$
									+ Integer.toString(decimals.length()));
			}
			if (options.getTotalDigits() != DecimalFormatOptions.ANY_DIGITS) {
				int len = whole.length()
						+ (decimals == null ? 0 : decimals.length());
				if (len > options.getTotalDigits())
					throw new UOMoNumberFormatException(
							UOMoNumberFormatException.Kind.RULE,
							"Only " //$NON-NLS-1$
									+ Integer.toString(options.getTotalDigits())
									+ " digits after the decimal are allowed, but found " //$NON-NLS-1$
									+ Integer.toString(len));
			}
		}
	}

	private String processInteger(boolean allowSign, boolean allowComplex,
			String context) throws UOMoNumberFormatException {
		if (!more())
			throw new UOMoNumberFormatException(TEXT_FORMAT,
					Messages.NumberValidator_Unexpected_End_of_Source_looking_for + context);
		StringBuffer b = new StringBuffer();
		if (allowSign && (peek() == '+' || peek() == '-')) {
			if (peek() == '+')
				next();
			else
				b.append(next());
		}
		if (!more())
			throw new UOMoNumberFormatException(TEXT_FORMAT,
					Messages.NumberValidator_Unexpected_End_of_Source_after_Sign_looking_for
							+ context);
		if (allowComplex && peek() == 'N') {
			processSequence(Messages.NumberValidator_NaN, context);
			b.append("NaN"); //$NON-NLS-1$
		} else if (allowComplex && peek() == 'I') {
			processSequence("INF", context);
			b.append("INF");
		} else {
			if (peek() < '0' || peek() > '9')
				throw new UOMoNumberFormatException(TEXT_FORMAT,
						Messages.NumberValidator_Unexpected_Content_expecting_Start_of + peek() + "' at character " //$NON-NLS-2$
								+ pos() + " expecting the start of " + context); //$NON-NLS-1$
			while (more() && peek() >= '0' && peek() <= '9')
				b.append(next());
		}
		return b.toString();
	}

	private void processSequence(String mask, String context)
			throws UOMoNumberFormatException {
		for (int i = 0; i < mask.length(); i++) {
			if (!more())
				throw new UOMoNumberFormatException(TEXT_FORMAT,
						Messages.NumberValidator_Unexpected_End_of_Source + mask
								+ "' in " + context); //$NON-NLS-1$
			char ch = next();
			if (ch != mask.charAt(i))
				throw new UOMoNumberFormatException(TEXT_FORMAT,
						Messages.NumberValidator_Unexpected_Content_NaN + ch + "' at character " + pos() //$NON-NLS-2$
								+ " attempting to read 'NaN' in " + context); //$NON-NLS-1$
		}
		if (more())
			throw new UOMoNumberFormatException(TEXT_FORMAT,
					Messages.NumberValidator_Unexpected_Content_following_in_Decimal + peek() + "' at character " + pos() //$NON-NLS-2$
							+ " following '" + mask + "' in " + context); //$NON-NLS-1$ //$NON-NLS-2$

	}

	private void processDecimal() throws UOMoNumberFormatException {
		whole = processInteger(true, options == null || optionsAllowSpecial(),
				Messages.NumberValidator_a_number);
		if (more() && peek() == '.') {
			next();
			decimals = processInteger(false, false, Messages.NumberValidator_decimal_portion);
		}

	}

}