Merge pull request #6 from Faterou/master

Added getAlternatives to BnfParser, a test to test the function and c…
sylvainhalle · May 15, 2017 · f047128 · f047128
2 parents 9affc41 + 6550a75
commit f047128
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Showing 3 changed files with 51 additions and 1 deletion.
diff --git a/Source/Parsing/src/ca/uqac/lif/bullwinkle/BnfParser.java b/Source/Parsing/src/ca/uqac/lif/bullwinkle/BnfParser.java
@@ -20,6 +20,7 @@
 import java.io.File;
 import java.io.IOException;
 import java.io.PrintStream;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.Iterator;
@@ -295,6 +296,29 @@ public static List<BnfRule> getRules(String grammar) throws InvalidGrammarExcept
 		}
 		return rules;
 	}
+
+	/**
+	 * Returns the list of alternative rules
+	 * @param rule_name The rule you need the alternatives
+	 * @return a list of strings representing the alternatives
+	 */
+	public List<String> getAlternatives(String rule_name)
+	{
+		for (BnfRule rule : m_rules)
+	    {
+	      String lhs = rule.getLeftHandSide().getName();
+	      if (rule_name.compareTo(lhs) == 0)
+	      {
+	    	List<String> alternatives = new ArrayList<String>();
+	        for(TokenString alt : rule.getAlternatives())
+	        {
+	        	alternatives.add(alt.toString());
+	        }
+	        return alternatives;
+	      }
+	    }
+	    return null;
+	}
 
 	/**
 	 * Adds a rule to the parser at a specific position.

diff --git a/Source/Parsing/src/ca/uqac/lif/bullwinkle/BnfRule.java b/Source/Parsing/src/ca/uqac/lif/bullwinkle/BnfRule.java
@@ -212,7 +212,7 @@ public List<TokenString> getAlternatives()
 	 * Retrieves the left-hand side symbol of the rule
 	 * @return The left-hand side symbol
 	 */
-	NonTerminalToken getLeftHandSide()
+	public NonTerminalToken getLeftHandSide()
 	{
 		return m_leftHandSide;
 	}

diff --git a/Source/ParsingTest/src/ca/uqac/lif/bullwinkle/ParserTest.java b/Source/ParsingTest/src/ca/uqac/lif/bullwinkle/ParserTest.java
@@ -18,6 +18,8 @@
 package ca.uqac.lif.bullwinkle;
 import static org.junit.Assert.*;
 
+import java.util.List;
+
 import org.junit.Before;
 import org.junit.Test;
 
@@ -92,5 +94,29 @@ public void simpleValidGrammarFromFile()
       fail("Valid grammar has thrown an exception when parsed.");
     }
   }
+
+  @Test
+  public void getAlternativesTest()
+  {
+    boolean has_error = false;
+    BnfParser parser = new BnfParser();
+    try
+    {
+      parser.setGrammar("<S> := <a> | b;\n<a> := c;");
+    }
+    catch (BnfParser.InvalidGrammarException e)
+    {
+      has_error = true;
+    }
+    if (has_error)
+    {
+      fail("Valid grammar has thrown an exception when parsed.");
+    }
+
+    List<String> alternatives = parser.getAlternatives("<S>");
+
+    assertTrue(alternatives.get(0).compareTo("<a>") == 0);
+    assertTrue(alternatives.get(1).compareTo("b") == 0);
+  }
 
 }