Merge pull request #89 from rjcohn/master

Allow legal variable characters to be modified

src/com/udojava/evalex/Expression.java

@@ -381,8 +381,18 @@ public class Expression {
 	 * The {@link MathContext} to use for calculations.
 	 */
 	private MathContext mc = null;
-
-  /**
+
+	/**
+	 * The characters (other than letters and digits) allowed as the first character in a variable.
+	 */
+	private String firstVarChars = "_";
+
+	/**
+	 * The characters (other than letters and digits) allowed as the second or subsequent characters in a variable.
+	 */
+	private String varChars = "_";
+
+	/**
 	 * The original infix expression.
 	 */
 	private final String originalExpression;
@@ -662,8 +672,8 @@ public String next() {
 				token.append(minusSign);
 				pos++;
 				token.append(next());
-			} else if (Character.isLetter(ch) || (ch == '_')) {
-				while ((Character.isLetter(ch) || Character.isDigit(ch) || (ch == '_'))
+			} else if (Character.isLetter(ch) || firstVarChars.indexOf(ch) >= 0) {
+				while ((Character.isLetter(ch) || Character.isDigit(ch) || varChars.indexOf(ch) >= 0)
 						&& (pos < input.length())) {
 					token.append(input.charAt(pos++));
 					ch = pos == input.length() ? 0 : input.charAt(pos);
@@ -1280,6 +1290,32 @@ public Expression setRoundingMode(RoundingMode roundingMode) {
 		return this;
 	}
 
+	/**
+	 * Sets the characters other than letters and digits that are valid as the
+	 * first character of a variable.
+	 *
+	 * @param chars
+	 *            The new set of variable characters.
+	 * @return The expression, allows to chain methods.
+	 */
+	public Expression setFirstVariableCharacters(String chars) {
+		this.firstVarChars = chars;
+		return this;
+	}
+
+	/**
+	 * Sets the characters other than letters and digits that are valid as the
+	 * second and subsequent characters of a variable.
+	 *
+	 * @param chars
+	 *            The new set of variable characters.
+	 * @return The expression, allows to chain methods.
+	 */
+	public Expression setVariableCharacters(String chars) {
+		this.varChars = chars;
+		return this;
+	}
+
 	/**
 	 * Adds an operator to the list of supported operators.
 	 * 

tests/com/udojava/evalex/AllTests.java

@@ -9,6 +9,6 @@
 		TestVariables.class, TestBooleans.class, TestCustoms.class,
 		TestNested.class, TestVarArgs.class, TestSciNotation.class,
 		TestExposedComponents.class, TestCaseInsensitive.class,
-		TestLazyIf.class, TestGetUsedVariables.class })
+		TestLazyIf.class, TestGetUsedVariables.class, TestVariableCharacters.class })
 public class AllTests {
 }

tests/com/udojava/evalex/TestVariableCharacters.java

@@ -0,0 +1,60 @@
+package com.udojava.evalex;
+
+import org.junit.Test;
+
+import java.math.BigDecimal;
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+public class TestVariableCharacters {
+
+	@Test
+	public void testBadVarChar() {
+		String err = "";
+		try {
+			Expression expression = new Expression("a.b/2*PI+MIN(e,b)");
+			expression.eval();
+		} catch (Expression.ExpressionException e) {
+			err = e.getMessage();
+		}
+		assertEquals("Unknown operator '.' at position 2", err);
+	}
+
+	@Test
+	public void testAddedVarChar() {
+		String err = "";
+		Expression expression;
+
+		try {
+			expression = new Expression("a.b/2*PI+MIN(e,b)").setVariableCharacters("_");
+			expression.eval();
+		} catch (Expression.ExpressionException e) {
+			err = e.getMessage();
+		}
+		assertEquals("Unknown operator '.' at position 2", err);
+
+		try {
+			expression = new Expression("a.b/2*PI+MIN(e,b)").setVariableCharacters("_.");
+			expression.eval();
+		} catch (Expression.ExpressionException e) {
+			err = e.getMessage();
+		}
+		assertEquals("Unknown operator or function: a.b", err);
+
+		expression = new Expression("a.b/2*PI+MIN(e,b)").setVariableCharacters("_.");
+		assertEquals("5.859875", expression.with("a.b", "2").and("b", "3").eval().toPlainString());
+
+		try {
+			expression = new Expression(".a.b/2*PI+MIN(e,b)").setVariableCharacters("_.");
+			expression.eval();
+		} catch (Expression.ExpressionException e) {
+			err = e.getMessage();
+		}
+		assertEquals("Unknown operator '.' at position 1", err);
+
+		expression = new Expression("a.b/2*PI+MIN(e,b)").setVariableCharacters("_.").setFirstVariableCharacters(".");
+		assertEquals("5.859875", expression.with("a.b", "2").and("b", "3").eval().toPlainString());
+	}
+}