add indentation level to RdfXmlConfig

fix #156

sophia/examples/serialize.rs

@@ -30,7 +30,7 @@ use sophia::turtle::serializer::{
     turtle::{TurtleConfig, TurtleSerializer},
 };
 #[cfg(feature = "xml")]
-use sophia::xml::serializer::RdfXmlSerializer;
+use sophia::xml::serializer::{RdfXmlConfig, RdfXmlSerializer};
 
 fn main() {
     let input = BufReader::new(stdin());
@@ -63,7 +63,12 @@ fn main() {
             JsonLdSerializer::new_with_options(out, JsonLdOptions::new().with_spaces(2)),
         ),
         #[cfg(feature = "xml")]
-        "rdfxml" | "rdf" => serialize_triples(quad_source, RdfXmlSerializer::new(out)),
+        "rdfxml" | "rdf" => {
+            let indent = if pretty { 4 } else { 0 };
+            let config = RdfXmlConfig::new().with_identation(indent);
+            let ser = RdfXmlSerializer::new_with_config(out, config);
+            serialize_triples(quad_source, ser)
+        }
         _ => {
             eprintln!("Unrecognized format: {}", format);
             std::process::exit(-1);

xml/src/serializer.rs

@@ -18,10 +18,27 @@ use std::io;
 
 /// RDF/XML serializer configuration.
 #[derive(Clone, Debug, Default)]
-pub struct RdfXmlConfig {}
+pub struct RdfXmlConfig {
+    indentation: usize,
+}
 
 impl RdfXmlConfig {
-    // TODO add ways to customize namespaces
+    /// Size of the indentation to use in the serialization.
+    /// (defaults to 0, meaning no indentation nor linebreaks)
+    pub fn indentation(&self) -> usize {
+        self.indentation
+    }
+
+    /// Build a new default [`RdfXmlConfig`]
+    pub fn new() -> Self {
+        Default::default()
+    }
+
+    /// Transform an [`RdfXmlConfig`] by setting the [`indentation`](RdfXmlConfig::indentation).
+    pub fn with_identation(mut self, i: usize) -> Self {
+        self.indentation = i;
+        self
+    }
 }
 
 /// RDF/XML serializer.
@@ -65,7 +82,12 @@ where
         TS: TripleSource,
     {
         // temporarily move out self.write
-        let mut tf = RdfXmlFormatter::new(&mut self.write).map_err(SinkError)?;
+        let res = if self.config.indentation > 0 {
+            RdfXmlFormatter::with_indentation(&mut self.write, self.config.indentation)
+        } else {
+            RdfXmlFormatter::new(&mut self.write)
+        };
+        let mut tf = res.map_err(SinkError)?;
         rio_format_triples(&mut tf, source)?;
         tf.finish().map_err(SinkError)?;
         Ok(self)
@@ -132,4 +154,23 @@ pub(crate) mod test {
         }
         Ok(())
     }
+
+    #[test]
+    fn roundtrip_with_ident() -> Result<(), Box<dyn std::error::Error>> {
+        let config = RdfXmlConfig::new().with_identation(4);
+        for rdfxml in TESTS {
+            println!("==========\n{}\n----------", rdfxml);
+            let g1: Vec<[SimpleTerm; 3]> = crate::parser::parse_str(rdfxml).collect_triples()?;
+
+            let out = RdfXmlSerializer::new_stringifier_with_config(config.clone())
+                .serialize_triples(g1.triples())?
+                .to_string();
+            println!("{}", &out);
+
+            let g2: Vec<[SimpleTerm; 3]> = crate::parser::parse_str(&out).collect_triples()?;
+
+            assert!(isomorphic_graphs(&g1, &g2)?);
+        }
+        Ok(())
+    }
 }