Validation of the format parameters (suggested by Bob Smith in SANDBOX-291)

git-svn-id: https://svn.apache.org/repos/asf/commons/sandbox/csv/trunk@1298234 13f79535-47bb-0310-9956-ffa450edef68

Author: ebourg

src/main/java/org/apache/commons/csv/CSVFormat.java

@@ -126,6 +126,42 @@ public class CSVFormat implements Cloneable, Serializable {
         this.emptyLinesIgnored = emptyLinesIgnored;
     }
 
+    /**
+     * Returns true if the given character is a line break character.
+     * 
+     * @param c the character to check
+     * 
+     * @return true if <code>c</code> is a line break character
+     */
+    private static boolean isLineBreak(char c) {
+        return c == '\n' || c == '\r';
+    }
+
+    /**
+     * Verifies the consistency of the parameters and throws an IllegalArgumentException if necessary.
+     */
+    void validate() throws IllegalArgumentException {
+        if (delimiter == encapsulator) {
+            throw new IllegalArgumentException("The encapsulator character and the delimiter cannot be the same (\"" + encapsulator + "\")");
+        }
+        
+        if (delimiter == escape) {
+            throw new IllegalArgumentException("The escape character and the delimiter cannot be the same (\"" + escape + "\")");
+        }
+        
+        if (delimiter == commentStart) {
+            throw new IllegalArgumentException("The comment start character and the delimiter cannot be the same (\"" + commentStart + "\")");
+        }
+        
+        if (encapsulator != DISABLED && encapsulator == commentStart) {
+            throw new IllegalArgumentException("The comment start character and the encapsulator cannot be the same (\"" + commentStart + "\")");
+        }
+        
+        if (escape != DISABLED && escape == commentStart) {
+            throw new IllegalArgumentException("The comment start and the escape character cannot be the same (\"" + commentStart + "\")");
+        }
+    }
+
     /**
      * Returns the character delimiting the values (typically ';', ',' or '\t').
      * 
@@ -140,8 +176,13 @@ public char getDelimiter() {
      * 
      * @param delimiter the delimiter character
      * @return A copy of this format using the specified delimiter character
+     * @throws IllegalArgumentException thrown if the specified character is a line break
      */
     public CSVFormat withDelimiter(char delimiter) {
+        if (isLineBreak(delimiter)) {
+            throw new IllegalArgumentException("The delimiter cannot be a line break");
+        }
+        
         CSVFormat format = clone();
         format.delimiter = delimiter;
         return format;
@@ -161,8 +202,13 @@ public char getEncapsulator() {
      * 
      * @param encapsulator the encapsulator character
      * @return A copy of this format using the specified encapsulator character
+     * @throws IllegalArgumentException thrown if the specified character is a line break
      */
     public CSVFormat withEncapsulator(char encapsulator) {
+        if (isLineBreak(encapsulator)) {
+            throw new IllegalArgumentException("The encapsulator cannot be a line break");
+        }
+        
         CSVFormat format = clone();
         format.encapsulator = encapsulator;
         return format;
@@ -186,8 +232,13 @@ public char getCommentStart() {
      * 
      * @param commentStart the comment start marker
      * @return A copy of this format using the specified character as the comment start marker
+     * @throws IllegalArgumentException thrown if the specified character is a line break
      */
     public CSVFormat withCommentStart(char commentStart) {
+        if (isLineBreak(commentStart)) {
+            throw new IllegalArgumentException("The comment start character cannot be a line break");
+        }
+        
         CSVFormat format = clone();
         format.commentStart = commentStart;
         return format;
@@ -216,8 +267,13 @@ public char getEscape() {
      * 
      * @param escape the escape character
      * @return A copy of this format using the specified escape character
+     * @throws IllegalArgumentException thrown if the specified character is a line break
      */
     public CSVFormat withEscape(char escape) {
+        if (isLineBreak(escape)) {
+            throw new IllegalArgumentException("The escape character cannot be a line break");
+        }
+        
         CSVFormat format = clone();
         format.escape = escape;
         return format;

src/main/java/org/apache/commons/csv/CSVParser.java

@@ -76,6 +76,7 @@ public class CSVParser implements Iterable<String[]> {
      * CSV parser using the default {@link CSVFormat}.
      *
      * @param input a Reader containing "csv-formatted" input
+     * @throws IllegalArgumentException thrown if the parameters of the format are inconsistent
      */
     public CSVParser(Reader input) {
         this(input, CSVFormat.DEFAULT);
@@ -86,8 +87,11 @@ public CSVParser(Reader input) {
      *
      * @param input    a Reader containing "csv-formatted" input
      * @param format the CSVFormat used for CSV parsing
+     * @throws IllegalArgumentException thrown if the parameters of the format are inconsistent
      */
     public CSVParser(Reader input, CSVFormat format) {
+        format.validate();
+        
         if (format.isUnicodeEscapesInterpreted()) {
             input = new UnicodeUnescapeReader(input);
         }
@@ -100,6 +104,7 @@ public CSVParser(Reader input, CSVFormat format) {
      *
      * @param input    a String containing "csv-formatted" input
      * @param format the CSVFormat used for CSV parsing
+     * @throws IllegalArgumentException thrown if the parameters of the format are inconsistent
      */
     public CSVParser(String input, CSVFormat format) {
         this(new StringReader(input), format);

src/main/java/org/apache/commons/csv/CSVPrinter.java

@@ -39,11 +39,14 @@ public class CSVPrinter {
      * is supported. Hybrid formats (encapsulation and escaping with a different character) are not supported.
      *
      * @param out    stream to which to print.
-     * @param format describes the CSV variation.
+     * @param format the CSV format. If null the default format is used ({@link CSVFormat#DEFAULT})
+     * @throws IllegalArgumentException thrown if the parameters of the format are inconsistent
      */
     public CSVPrinter(Appendable out, CSVFormat format) {
         this.out = out;
         this.format = format == null ? CSVFormat.DEFAULT : format;
+        
+        this.format.validate();
     }
 
     // ======================================================

src/test/java/org/apache/commons/csv/CSVFormatTest.java

@@ -70,4 +70,78 @@ public void testFormat() {
         assertEquals("a,b,c", format.format("a", "b", "c"));
         assertEquals("\"x,y\",z", format.format("x,y", "z"));
     }
+    
+    public void testValidation() {
+        CSVFormat format = CSVFormat.DEFAULT;
+        
+        try {
+            format.withDelimiter('\n');
+            fail();
+        } catch (IllegalArgumentException e) {
+            // expected
+        }
+        
+        try {
+            format.withEscape('\r');
+            fail();
+        } catch (IllegalArgumentException e) {
+            // expected
+        }
+        
+        try {
+            format.withEncapsulator('\n');
+            fail();
+        } catch (IllegalArgumentException e) {
+            // expected
+        }
+        
+        try {
+            format.withCommentStart('\r');
+            fail();
+        } catch (IllegalArgumentException e) {
+            // expected
+        }
+        
+        try {
+            format.withDelimiter('!').withEscape('!').validate();
+            fail();
+        } catch (IllegalArgumentException e) {
+            // expected
+        }
+        
+        try {
+            format.withDelimiter('!').withCommentStart('!').validate();
+            fail();
+        } catch (IllegalArgumentException e) {
+            // expected
+        }
+        
+        try {
+            format.withEncapsulator('!').withCommentStart('!').validate();
+            fail();
+        } catch (IllegalArgumentException e) {
+            // expected
+        }
+        
+        format.withEncapsulator(CSVFormat.DISABLED).withCommentStart(CSVFormat.DISABLED).validate();
+        
+        try {
+            format.withEscape('!').withCommentStart('!').validate();
+            fail();
+        } catch (IllegalArgumentException e) {
+            // expected
+        }
+        
+        format.withEscape(CSVFormat.DISABLED).withCommentStart(CSVFormat.DISABLED).validate();
+        
+        
+        try {
+            format.withEncapsulator('!').withDelimiter('!').validate();
+            fail();
+        } catch (IllegalArgumentException e) {
+            // expected
+        }
+        
+        
+    }
 }