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diff --git a/bundles/org.simantics.databoard/src/org/simantics/databoard/units/internal/parser/UnitParser.java b/bundles/org.simantics.databoard/src/org/simantics/databoard/units/internal/parser/UnitParser.java
new file mode 100644
index 000000000..31723aacc
--- /dev/null
+++ b/bundles/org.simantics.databoard/src/org/simantics/databoard/units/internal/parser/UnitParser.java
@@ -0,0 +1,149 @@
+/*******************************************************************************
+ *  Copyright (c) 2010 Association for Decentralized Information Management in
+ *  Industry THTH ry.
+ *  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:
+ *      VTT Technical Research Centre of Finland - initial API and implementation
+ *******************************************************************************/
+package org.simantics.databoard.units.internal.parser;
+
+import org.simantics.databoard.units.internal.UnitParseException;
+
+public abstract class UnitParser {
+
+	String string;
+	int pos;
+	
+	int nextChar;
+	int sign;
+	
+	public UnitParser() {
+	}
+
+	void next() {
+		++pos;
+		if(pos >= string.length())
+			nextChar = -1;
+		else
+			nextChar = string.charAt(pos);
+	}
+	
+	public void unit(String string, int sign) throws UnitParseException {
+		this.string = string;
+		this.pos = -1;
+		this.sign = sign;
+		next();
+		
+		expression();
+		expect(-1);
+	}
+	
+	/* Grammar
+	 * 
+	 * unit_expression: unit_numerator [ "/" unit_denominator ]
+	 * unit_numerator: "1" | unit_factors | "(" unit_expression ")"
+	 * unit_denominator: unit_factor | "(" unit_expression ")"
+	 * unit_factors: unit_factor [ "." unit_factors ]
+	 * unit_factor: unit_operand [ unit_exponent ]
+	 * unit_exponent: [ "+" | "-" ] integer
+	 * unit_operand: unit_symbol | unit_prefix unit_symbol 
+	 */
+	
+	void expression() throws UnitParseException {
+		numerator();
+		if(nextChar == '/') {
+			next();
+			denominator();
+		}		
+	}
+	
+	void numerator() throws UnitParseException {
+		if(nextChar == '1')
+			next();
+		else if(nextChar == '(') {
+			next();
+			expression();
+			skip(')');
+		}
+		else
+			factors();
+	}
+
+	void denominator() throws UnitParseException {
+		sign = -sign;
+		if(nextChar == '(') {
+			next();
+			expression();
+			skip(')');
+		}
+		else
+			factor();
+		sign = -sign;
+	}
+	
+	void factors() throws UnitParseException {
+		while(true) {
+			factor();
+			if(nextChar == '.')
+				next();
+			else
+			    break;
+		}
+	}
+	
+	void factor() throws UnitParseException {
+		// Base
+		int factorBegin = pos;
+		while((nextChar >= 'a' && nextChar <= 'z') || (nextChar >= 'A' && nextChar <= 'Z') || (nextChar=='µ') || nextChar=='(' || nextChar==')' || nextChar=='%') 
+			next();
+		int exponentBegin = pos;
+		if(factorBegin == exponentBegin)
+			throw new UnitParseException(string, 
+					"Expected base unit name, but got " + charName(nextChar) + " at position " + pos + ".");	
+		String baseUnit = string.substring(factorBegin, exponentBegin);
+		
+		// Exponent
+		if(nextChar == '-' || nextChar == '+' || (nextChar >= '0' && nextChar <= '9')) {
+			next();
+			while(nextChar >= '0' && nextChar <= '9')
+				next();
+		}
+		int exponentEnd = pos;
+		if(exponentEnd > exponentBegin) {
+			String exponentString = string.substring(exponentBegin, exponentEnd);
+			try {
+				visit(baseUnit, sign * Integer.parseInt(exponentString));
+			} catch(NumberFormatException e) {
+				throw new UnitParseException(string, 
+						"Invalid exponent \"" + exponentString + "\" at position " + pos + ".");	
+			}
+		}
+		else
+			visit(baseUnit, sign);
+	}
+			
+	private void skip(char c) throws UnitParseException {
+		expect(c);			
+		next();
+	}
+	
+	private static String charName(int c) {
+		if(c >= 0)
+			return "'" + Character.toString((char)c) + "'";
+		else
+			return "end of unit";
+	}
+	
+	private void expect(int c) throws UnitParseException {
+		if(nextChar != c)
+			throw new UnitParseException(string, 
+					"Expected " + charName(c) + ", but got " + charName(nextChar) + " at position " + pos + ".");	
+	}
+	
+	public abstract void visit(String baseUnit, int exponent);
+	
+}