Converts between delimited strings and lists (or sets) of strings

Closes #4

src/main/java/edu/unl/cse/csv_io/CSVReaderWriter.java

@@ -61,8 +61,6 @@ public class CSVReaderWriter {
         return destination;
     }
 
-    // I'd like to replace this with something that uses openCSV, but it works, and openCSV doesn't seem to have
-    // writers that take map<string,string>
     public static boolean writeCSV(String filename, Collection<Map<String, String>> data) {
         boolean wroteFile = true;
         ClassLoader classLoader = CSVReaderWriter.class.getClassLoader();
@@ -114,6 +112,60 @@ public class CSVReaderWriter {
         return fieldArray;
     }
 
+    public static String createDelimitedCollection(Collection<String> collection, String delimiter) {
+        if (delimiter.equals("\"")) {
+            throw new IllegalArgumentException("The double-quote character \" cannot be a delimiter.");
+        }
+        StringBuilder delimitedCollection = new StringBuilder();
+        int tokensRemaining = collection.size();
+        for (String datum : collection) {
+            if (datum.contains(delimiter)) {
+                delimitedCollection.append("\"").append(datum).append("\"");
+            } else {
+                delimitedCollection.append(datum);
+            }
+            if (--tokensRemaining > 0) {
+                delimitedCollection.append(delimiter);
+            }
+        }
+        return delimitedCollection.toString();
+    }
+
+    public static List<String> createFreeList(String delimitedCollection, String delimiter) {
+        return (List<String>) createFreeCollection(delimitedCollection, delimiter, new LinkedList<>());
+    }
+
+    public static Set<String> createFreeSet(String delimitedCollection, String delimiter) {
+        return (Set<String>) createFreeCollection(delimitedCollection, delimiter, new HashSet<>());
+    }
+
+    static Collection<String> createFreeCollection(String delimitedCollection, String delimiter,
+                                                   Collection<String> collection) {
+        // NOTE: if there are 2n+1 quotes, where n>0, then the delimitedCollection is ambiguous
+        // In practice, this code treats the final quote as the floating quote (but do not guarantee it will do so)
+        // If this isn't what you want, then don't pass an ambiguous delimitedCollection
+        if (delimiter.equals("\"")) {
+            throw new IllegalArgumentException("The double-quote character \" cannot be a delimiter.");
+        }
+        List<String> preliminaryCollection = new LinkedList<>();
+        if (!Objects.equals(delimitedCollection, "")) {
+            String[] splitOnQuotedSegments = delimitedCollection.split(" (?=\")|(?<=\") ");
+            for (String segment : splitOnQuotedSegments) {
+                String trimmedSegment = segment.trim();                         // use .strip() if we move to Java 11
+                if (!trimmedSegment.equals("")) {
+                    if (trimmedSegment.startsWith("\"") && trimmedSegment.endsWith("\"")) {
+                        preliminaryCollection.add(trimmedSegment.substring(1, trimmedSegment.length() - 1));
+                    } else {
+                        String[] splitOnDelimiter = trimmedSegment.split(delimiter);
+                        preliminaryCollection.addAll(Arrays.asList(splitOnDelimiter));
+                    }
+                }
+            }
+        }
+        collection.addAll(preliminaryCollection);
+        return collection;
+    }
+
     /* LEGACY METHODS */
     public static Set<Map<String, String>> readCSV(String filename) {
         return readCSVasSet(filename);

src/test/java/edu/unl/cse/csv_io/CSVReaderWriterTest.java

@@ -217,4 +217,135 @@ public class CSVReaderWriterTest {
         assertTrue(expectedCSVStringOption1.equals(output) || expectedCSVStringOption2.equals(output));
         assertThat(output, either(is(expectedCSVStringOption1)).or(is(expectedCSVStringOption2)));
     }
+
+    @Test
+    public void testCreateDelimitedCollection() {
+        // Input
+        String[] inputArray = {"foo", "bar", "baz plugh"};
+        List<String> inputList = Arrays.asList(inputArray);
+        // Oracle
+        String expectedOutput = "foo bar \"baz plugh\"";
+        // Output
+        String actualOutput = CSVReaderWriter.createDelimitedCollection(inputList, " ");
+        // Compare
+        assertEquals(expectedOutput, actualOutput);
+    }
+
+    @Test
+    public void testCreateDelimitedCollectionFromTrivialList() {
+        // Input
+        List<String> input = new ArrayList<>(1);
+        input.add("foo");
+        // Oracle
+        String expectedOutput = "foo";
+        // Output
+        String actualOutput = CSVReaderWriter.createDelimitedCollection(input, " ");
+        // Compare
+        assertEquals(expectedOutput, actualOutput);
+    }
+
+    @Test
+    public void testCreateDelimitedCollectionFromVacuousList() {
+        // Input
+        List<String> input = new ArrayList<>();
+        // Oracle
+        String expectedOutput = "";
+        // Output
+        String actualOutput = CSVReaderWriter.createDelimitedCollection(input, " ");
+        // Compare
+        assertEquals(expectedOutput, actualOutput);
+    }
+
+    @Test
+    public void testCreateFreeCollectionSimpleCase() {
+        // Input
+        String input = "one two three four";
+        // Oracle
+        String[] expectedOutputArray = {"one", "two", "three", "four"};
+        Collection<String> expectedOutput = Arrays.asList(expectedOutputArray);
+        // Output
+        Collection<String> actualOutput = CSVReaderWriter.createFreeCollection(input, " ", new ArrayList<>());
+        // Compare
+        assertEquals(expectedOutput, actualOutput);
+    }
+
+    @Test
+    public void testCreateFreeCollectionTrivialCase() {
+        // Input
+        String input = "one";
+        // Oracle
+        String[] expectedOutputArray = {"one"};
+        Collection<String> expectedOutput = Arrays.asList(expectedOutputArray);
+        // Output
+        Collection<String> actualOutput = CSVReaderWriter.createFreeCollection(input, " ", new ArrayList<>());
+        // Compare
+        assertEquals(expectedOutput, actualOutput);
+    }
+
+    @Test
+    public void testCreateFreeCollectionEmptyString() {
+        // Input
+        String input = "";
+        // Oracle
+        Collection<String> expectedOutput = new ArrayList<>();
+        // Output
+        Collection<String> actualOutput = CSVReaderWriter.createFreeCollection(input, " ", new ArrayList<>());
+        // Compare
+        assertEquals(expectedOutput, actualOutput);
+        assertNotNull(actualOutput);
+        assertEquals(0, actualOutput.size());
+    }
+
+    @Test
+    public void testCreateFreeCollectionNullString() {
+        // Input
+        String input = "";
+        // Oracle
+        Collection<String> expectedOutput = new ArrayList<>();
+        // Output
+        Collection<String> actualOutput = CSVReaderWriter.createFreeCollection(input, " ", new ArrayList<>());
+        // Compare
+        assertEquals(expectedOutput, actualOutput);
+        assertNotNull(actualOutput);
+        assertEquals(0, actualOutput.size());
+    }
+
+    @Test
+    public void testCreateFreeCollectionQuotedSubstring() {
+        // Input
+        String input = "one \"two\" three four \"five\" six";
+        // Oracle
+        String[] expectedOutputArray = {"one", "two", "three", "four", "five", "six"};
+        Collection<String> expectedOutput = Arrays.asList(expectedOutputArray);
+        // Output
+        Collection<String> actualOutput = CSVReaderWriter.createFreeCollection(input, " ", new ArrayList<>());
+        // Compare
+        assertEquals(expectedOutput, actualOutput);
+    }
+
+    @Test
+    public void testCreateFreeCollectionQuotedDelimiter() {
+        // Input
+        String input = "one \"two three\" \"four five\" six";
+        // Oracle
+        String[] expectedOutputArray = {"one", "two three", "four five", "six"};
+        Collection<String> expectedOutput = Arrays.asList(expectedOutputArray);
+        // Output
+        Collection<String> actualOutput = CSVReaderWriter.createFreeCollection(input, " ", new ArrayList<>());
+        // Compare
+        assertEquals(expectedOutput, actualOutput);
+    }
+
+    @Test
+    public void testCreateFreeCollectionSingleQuote() {
+        // Input
+        String input = "one two three\" four five six";
+        // Oracle
+        String[] expectedOutputArray = {"one", "two", "three\"", "four", "five", "six"};
+        Collection<String> expectedOutput = Arrays.asList(expectedOutputArray);
+        // Output
+        Collection<String> actualOutput = CSVReaderWriter.createFreeCollection(input, " ", new ArrayList<>());
+        // Compare
+        assertEquals(expectedOutput, actualOutput);
+    }
 }
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