Progress on modularizing escpos.

src/escpos/printer.rs

@@ -0,0 +1,49 @@
+use crate::escpos::{errors::EscPosError, job::Job};
+use std::io::Write;
+
+pub struct Printer {
+    pub queue: Vec<Job>,
+    pub max_width: u16,
+}
+impl Printer {
+    pub fn new(max_width: u16) -> Self {
+        Printer {
+            queue: Vec::new(),
+            max_width: max_width,
+        }
+    }
+
+    pub fn new_job(&mut self) -> Result<&mut Job, EscPosError> {
+        self.queue.push(Job::new(self.max_width));
+        self.queue.last_mut().ok_or(EscPosError::InvalidQueueIndex)
+    }
+    pub fn print_job(&mut self, writer: &mut impl Write) -> Result<(), EscPosError> {
+        // let page_feed: u8 = 0x0A;
+        let job = self
+            .queue
+            .extract_if(.., |j| j.ready)
+            .next()
+            .ok_or(EscPosError::EmptyQueue)?;
+
+        // writer.write(&[page_feed]).unwrap(); // FIXME: remove unwraps
+        writer.write(&job.content).unwrap();
+        // writer.write(&[page_feed]).unwrap();
+
+        Ok(())
+    }
+    pub fn export_job(&mut self) -> Result<Vec<u8>, EscPosError> {
+        let page_feed: u8 = 0x0A;
+        let job = self
+            .queue
+            .extract_if(.., |j| j.ready)
+            .next()
+            .ok_or(EscPosError::EmptyQueue)?;
+
+        let mut out = Vec::with_capacity(2 + job.content.len());
+        out.push(page_feed);
+        out.extend(job.content);
+        out.push(page_feed);
+
+        Ok(out)
+    }
+}