refactor: simpler buffer handling with dynamic dispatch (#17)

* refactor(io): drop boilerplate enums

* refactor(io): use dynamic dispatch for io types

* fix: drop io mod

src/converter.rs

@@ -20,18 +20,19 @@
 //! This module contains the `RdfIO` trait which is used to parse and serialize RDF graphs.
 //! Each RDF serialization format should implement this trait.
 //!
+use std::io::{BufRead, Write};
+use std::boxed::Box;
 
-use crate::io::{Input, Output};
 use sophia::api::prelude::TripleParser;
 use sophia::api::serializer::TripleSerializer;
 use sophia::api::source::TripleSource;
 use sophia::inmem::graph::FastGraph;
 
 /// The `RdfIO` trait is used to parse and serialize RDF graphs.
 
-pub trait RdfIO<'a, P: TripleParser<Input>, F: TripleSerializer> {
+pub trait RdfIO<'a, P: TripleParser<Box<dyn BufRead>>, F: TripleSerializer> {
     /// Parse an RDF graph from an input source to an in-memory graph.
-    fn parse(&self, input: Input) -> Result<FastGraph, String> {
+    fn parse(&self, input: Box<dyn BufRead>) -> Result<FastGraph, String> {
         let mut graph = FastGraph::new();
         match self.parser().parse(input).add_to_graph(&mut graph) {
             Ok(_) => Ok(graph),
@@ -40,7 +41,7 @@ pub trait RdfIO<'a, P: TripleParser<Input>, F: TripleSerializer> {
     }
 
     /// Serialize an in-memory RDF graph to an output source.
-    fn serialize(&self, writer: Output, graph: FastGraph) -> Result<(), String> {
+    fn serialize(&self, writer: Box<dyn Write>, graph: FastGraph) -> Result<(), String> {
         let mut formatter = self.serializer(writer);
         match formatter.serialize_graph(&graph) {
             Ok(_) => Ok(()),
@@ -52,5 +53,5 @@ pub trait RdfIO<'a, P: TripleParser<Input>, F: TripleSerializer> {
     fn parser(&self) -> P;
 
     /// Create a new serializer for this format.
-    fn serializer(&self, writer: Output) -> F;
+    fn serializer(&self, writer: Box<dyn Write>) -> F;
 }

src/formats.rs

@@ -18,9 +18,10 @@
 //! # Implementation of concrete RDF formats
 //!
 //! This module implements `RdfIO` trait for each RDF serialization format.
+use std::io::{BufRead, Write};
+
 use crate::cli::GraphFormat;
 use crate::converter::RdfIO;
-use crate::io::{Input, Output};
 use sophia::inmem::graph::FastGraph;
 use sophia::turtle::parser::nt::NTriplesParser;
 use sophia::turtle::parser::turtle::TurtleParser;
@@ -40,7 +41,7 @@ pub struct RdfParser {
 }
 
 impl RdfParser {
-    pub fn new(input: Input, format: GraphFormat) -> Result<Self, String> {
+    pub fn new(input: Box<dyn BufRead>, format: GraphFormat) -> Result<Self, String> {
         let graph = match format {
             GraphFormat::NTriples => NTriples.parse(input),
             GraphFormat::Turtle => Turtle.parse(input),
@@ -55,40 +56,44 @@ impl RdfParser {
 pub struct RdfSerializer;
 
 impl RdfSerializer {
-    pub fn serialize(dest: Output, format: GraphFormat, graph: FastGraph) -> Result<(), String> {
+    pub fn serialize(
+        dest: Box<dyn Write>,
+        format: GraphFormat,
+        graph: FastGraph,
+    ) -> Result<(), String> {
         match format {
             GraphFormat::NTriples => NTriples.serialize(dest, graph),
             GraphFormat::Turtle => Turtle.serialize(dest, graph),
             GraphFormat::RdfXml => RdfXml.serialize(dest, graph),
         }
     }
 }
-impl<'a> RdfIO<'a, NTriplesParser, NtSerializer<Output>> for NTriples {
+impl<'a> RdfIO<'a, NTriplesParser, NtSerializer<Box<dyn Write>>> for NTriples {
     fn parser(&self) -> NTriplesParser {
         NTriplesParser {}
     }
 
-    fn serializer(&self, writer: Output) -> NtSerializer<Output> {
+    fn serializer(&self, writer: Box<dyn Write>) -> NtSerializer<Box<dyn Write>> {
         NtSerializer::new(writer)
     }
 }
 
-impl<'a> RdfIO<'a, TurtleParser, TurtleSerializer<Output>> for Turtle {
+impl<'a> RdfIO<'a, TurtleParser, TurtleSerializer<Box<dyn Write>>> for Turtle {
     fn parser(&self) -> TurtleParser {
         TurtleParser { base: None }
     }
 
-    fn serializer(&self, writer: Output) -> TurtleSerializer<Output> {
+    fn serializer(&self, writer: Box<dyn Write>) -> TurtleSerializer<Box<dyn Write>> {
         TurtleSerializer::new(writer)
     }
 }
 
-impl<'a> RdfIO<'a, RdfXmlParser, RdfXmlSerializer<Output>> for RdfXml {
+impl<'a> RdfIO<'a, RdfXmlParser, RdfXmlSerializer<Box<dyn Write>>> for RdfXml {
     fn parser(&self) -> RdfXmlParser {
         RdfXmlParser { base: None }
     }
 
-    fn serializer(&self, writer: Output) -> RdfXmlSerializer<Output> {
+    fn serializer(&self, writer: Box<dyn Write>) -> RdfXmlSerializer<Box<dyn Write>> {
         RdfXmlSerializer::new(writer)
     }
 }

src/main.rs

@@ -54,13 +54,13 @@
 mod cli;
 mod converter;
 mod formats;
-mod io;
 
 use crate::cli::{Args, GraphFormat};
-use crate::io::{Input, Output};
 use clap::Parser;
 use formats::{RdfParser, RdfSerializer};
 use std::error::Error;
+use std::fs::File;
+use std::io::{BufRead, BufReader, BufWriter, stdout};
 use std::path::Path;
 
 /// Infer RDF serialization format from file extension
@@ -87,8 +87,11 @@ fn main() -> Result<(), Box<dyn Error>> {
     };
     let output_format = args.output_format;
 
-    let input = Input::new(args.input_file);
-    let output = Output::new(None);
+    let input: Box<dyn BufRead> = match args.input_file.unwrap().as_ref() {
+        "-" =>  Box::new(BufReader::new(std::io::stdin())),
+        path => Box::new(BufReader::new(File::open(path)?)),
+    };
+    let output = Box::new(BufWriter::new(stdout()));
     let parser = RdfParser::new(input, input_format)?;
     if !args.no_out {
         RdfSerializer::serialize(output, output_format, parser.graph)?;