1 files changed, 99 insertions, 0 deletions
diff --git a/src/utils.rs b/src/utils.rs
new file mode 100644
index 0000000..41d3729
--- /dev/null
+++ b/src/utils.rs
@@ -0,0 +1,99 @@
+use quick_xml::events::{BytesEnd, BytesStart, BytesText, Event};
+use quick_xml::{Reader, Writer};
+
+use crate::error::{EncodingError, ParseError, Result};
+
+pub(crate) trait ReaderExt {
+    fn expect_tag(&mut self, end: &[u8], buf: &mut Vec<u8>) -> Result<()>;
+}
+
+impl<B> ReaderExt for Reader<B>
+where
+    B: std::io::BufRead,
+{
+    fn expect_tag(&mut self, end: &[u8], buf: &mut Vec<u8>) -> Result<()> {
+        loop {
+            match self.read_event(buf) {
+                // TODO: this isn't exactly right, but it's good enough for now.
+                Ok(Event::Decl(ref _d)) => continue,
+                Ok(Event::Start(ref e)) => {
+                    if e.name() != end {
+                        return Err(ParseError::UnexpectedTag(
+                            String::from_utf8_lossy(e.name()).into(),
+                            String::from_utf8_lossy(end).into(),
+                        )
+                        .into());
+                    }
+
+                    break;
+                }
+                Ok(_e) => {
+                    return Err(ParseError::UnexpectedEvent(
+                        //e,
+                        String::from_utf8_lossy(end).into(),
+                    )
+                    .into());
+                }
+                Err(e) => {
+                    return Err(ParseError::UnexpectedError(
+                        e.into(),
+                        String::from_utf8_lossy(end).into(),
+                    )
+                    .into())
+                }
+            };
+        }
+
+        Ok(())
+    }
+}
+
+pub(crate) trait WriterExt {
+    // High level functions
+    fn write_tag(&mut self, tag: &[u8], text: &str) -> Result<()> {
+        self.write_start_tag(tag)?;
+        self.write_text(text)?;
+        self.write_end_tag(tag)?;
+        Ok(())
+    }
+
+    fn write_safe_tag(&mut self, tag: &[u8], text: &str) -> Result<()> {
+        self.write_start_tag(tag)?;
+        self.write_safe_text(text)?;
+        self.write_end_tag(tag)?;
+        Ok(())
+    }
+
+    // Building blocks
+    fn write_start_tag(&mut self, tag: &[u8]) -> Result<()>;
+    fn write_end_tag(&mut self, tag: &[u8]) -> Result<()>;
+    fn write_text(&mut self, text: &str) -> Result<()>;
+    fn write_safe_text(&mut self, text: &str) -> Result<()>;
+}
+
+impl<W> WriterExt for Writer<W>
+where
+    W: std::io::Write,
+{
+    fn write_start_tag(&mut self, tag: &[u8]) -> Result<()> {
+        self.write_event(Event::Start(BytesStart::borrowed_name(tag)))
+            .map_err(EncodingError::from)?;
+        Ok(())
+    }
+
+    fn write_end_tag(&mut self, tag: &[u8]) -> Result<()> {
+        self.write_event(Event::End(BytesEnd::borrowed(tag)))
+            .map_err(EncodingError::from)?;
+        Ok(())
+    }
+    fn write_text(&mut self, text: &str) -> Result<()> {
+        self.write_event(Event::Text(BytesText::from_plain_str(text)))
+            .map_err(EncodingError::from)?;
+        Ok(())
+    }
+    fn write_safe_text(&mut self, text: &str) -> Result<()> {
+        self.write_event(Event::Text(BytesText::from_escaped_str(text)))
+            .map_err(EncodingError::from)?;
+        Ok(())
+    }
+}