From a083c63c75ec3bc9e9da11b1a9e4e98e0c263458 Mon Sep 17 00:00:00 2001
From: Enrico Daga <enrico.daga@open.ac.uk>
Date: Mon, 6 Feb 2023 12:24:47 +0000
Subject: [PATCH] Implement #342

---
 .../src/main/java/com/github/sparqlanything/cli/CLI.java | 9 +++++++++
 .../com/github/sparqlanything/cli/SPARQLAnything.java    | 9 +++++----
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/sparql-anything-cli/src/main/java/com/github/sparqlanything/cli/CLI.java b/sparql-anything-cli/src/main/java/com/github/sparqlanything/cli/CLI.java
index 9dea8f8e..ec5e8bd5 100644
--- a/sparql-anything-cli/src/main/java/com/github/sparqlanything/cli/CLI.java
+++ b/sparql-anything-cli/src/main/java/com/github/sparqlanything/cli/CLI.java
@@ -47,6 +47,9 @@ public class CLI {
 	public static final String OUTPUT = "o";
 	public static final String OUTPUT_LONG = "output";
 
+	public static final String OUTPUT_APPEND = "a";
+	public static final String OUTPUT_APPEND_LONG = "append";
+
 	public static final String FORMAT = "f";
 	public static final String FORMAT_LONG = "format";
 
@@ -118,6 +121,9 @@ void init(){
 		options.addOption(Option.builder(OUTPUT).argName("file").hasArg()
 				.desc("OPTIONAL - The path to the output file. [Default: STDOUT]").longOpt(OUTPUT_LONG).build());
 
+		options.addOption(Option.builder(OUTPUT_APPEND).hasArg(false)
+				.desc("OPTIONAL - Should output to file be appended? WARNING: this option does not ensure that the whole file is valid -- that is up to the user to set up the conditions (such as using NQ serialization and not using bnodes)").longOpt(OUTPUT_APPEND_LONG).build());
+
 		options.addOption(Option.builder(EXPLAIN).argName("explain").hasArg(false)
 				.desc("OPTIONAL - Explain query execution").longOpt(EXPLAIN_LONG).build());
 
@@ -172,6 +178,9 @@ public String getOutputFile() {
 		return commandLine.getOptionValue(CLI.OUTPUT);
 	}
 
+	public boolean getOutputAppend() {
+		return commandLine.hasOption(CLI.OUTPUT_APPEND);
+	}
 	public String getOutputPattern() {
 		return commandLine.getOptionValue(CLI.OUTPUTPATTERN);
 	}
diff --git a/sparql-anything-cli/src/main/java/com/github/sparqlanything/cli/SPARQLAnything.java b/sparql-anything-cli/src/main/java/com/github/sparqlanything/cli/SPARQLAnything.java
index 6c379b37..49f4dd2c 100644
--- a/sparql-anything-cli/src/main/java/com/github/sparqlanything/cli/SPARQLAnything.java
+++ b/sparql-anything-cli/src/main/java/com/github/sparqlanything/cli/SPARQLAnything.java
@@ -58,6 +58,7 @@
 import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
 import java.io.PrintStream;
 import java.net.MalformedURLException;
 import java.net.URL;
@@ -166,10 +167,10 @@ private static void executeQuery(String outputFormat, Dataset kb, Query query, P
 		}
 	}
 
-	private static PrintStream getPrintWriter(String fileName) throws FileNotFoundException {
+	private static PrintStream getPrintWriter(String fileName, boolean append) throws FileNotFoundException {
 
 		if (fileName != null) {
-			return new PrintStream(new File(fileName));
+			return new PrintStream(new FileOutputStream(fileName, append));
 		}
 
 		return System.out;
@@ -531,7 +532,7 @@ public static void main(String[] args) throws Exception {
 			if (inputFile == null && values == null) {
 				logger.debug("No input file");
 				Query q = QueryFactory.create(query);
-				executeQuery(cli.getFormat(q), kb, q, getPrintWriter(outputFileName));
+				executeQuery(cli.getFormat(q), kb, q, getPrintWriter(outputFileName, cli.getOutputAppend()));
 			} else {
 
 				if (inputFile != null && values != null) {
@@ -576,7 +577,7 @@ public static void main(String[] args) throws Exception {
 					}
 					try {
 						logger.trace("Executing Query: {}", q);
-						executeQuery(cli.getFormat(q), kb, q, getPrintWriter(outputFile));
+						executeQuery(cli.getFormat(q), kb, q, getPrintWriter(outputFile, cli.getOutputAppend()));
 					} catch (Exception e1) {
 						logger.error(
 								"Iteration " + parameters.getRowNumber() + " failed with error: " + e1.getMessage());