Introduce CsvWriter

[lgpl/argeo-commons.git] / basic / runtime / org.argeo.basic.nodeps / src / main / java / org / argeo / util / CsvWriter.java

diff --git a/basic/runtime/org.argeo.basic.nodeps/src/main/java/org/argeo/util/CsvWriter.java b/basic/runtime/org.argeo.basic.nodeps/src/main/java/org/argeo/util/CsvWriter.java
new file mode 100644 (file)
index 0000000..19086d6
--- /dev/null
+++ b/basic/runtime/org.argeo.basic.nodeps/src/main/java/org/argeo/util/CsvWriter.java
@@ -0,0 +1,81 @@
+package org.argeo.util;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.PrintWriter;
+import java.util.Iterator;
+import java.util.List;
+
+import org.argeo.ArgeoException;
+
+/** Write in CSV format. */
+public class CsvWriter {
+       private final PrintWriter out;
+
+       private char separator = ',';
+       private char quote = '\"';
+
+       /**
+        * Creates a CSV writer. The header will be written immediately to the
+        * stream.
+        * 
+        * @param out
+        *            the stream to write to. Caller is responsible for closing it.
+        */
+       public CsvWriter(OutputStream out) {
+               super();
+               this.out = new PrintWriter(out);
+       }
+
+       /**
+        * Write a CSV line. Also used to write a header if needed (this is
+        * transparent for the CSV writer): simply call it first, before writing the
+        * lines.
+        */
+       public void writeLine(List<?> tokens) {
+               try {
+                       Iterator<?> it = tokens.iterator();
+                       while (it.hasNext()) {
+                               writeToken(it.next().toString());
+                               if (it.hasNext())
+                                       out.print(separator);
+                       }
+                       out.print('\n');
+                       out.flush();
+               } catch (IOException e) {
+                       throw new ArgeoException("Could not write " + tokens, e);
+               }
+       }
+
+       protected void writeToken(String token) throws IOException {
+               // +2 for possible quotes, another +2 assuming there would be an already
+               // quoted string where quotes needs to be duplicated
+               // another +2 for safety
+               StringBuffer buf = new StringBuffer(token.length() + 6);
+               char[] arr = token.toCharArray();
+               boolean shouldQuote = false;
+               for (char c : arr) {
+                       if (!shouldQuote) {
+                               if (c == separator)
+                                       shouldQuote = true;
+                               if (c == '\n')
+                                       shouldQuote = true;
+                       }
+
+                       if (c == quote) {
+                               shouldQuote = true;
+                               // duplicate quote
+                               buf.append(quote);
+                       }
+
+                       // generic case
+                       buf.append(c);
+               }
+
+               if (shouldQuote == true)
+                       out.print(quote);
+               out.print(buf.toString());
+               if (shouldQuote == true)
+                       out.print(quote);
+       }
+}