seeking logic

1 files changed, 25 insertions, 20 deletions

diff --git a/matroska/src/write.rs b/matroska/src/write.rs
index 6f8aad4..2555380 100644
--- a/matroska/src/write.rs
+++ b/matroska/src/write.rs
@@ -5,19 +5,16 @@
 */
 use crate::{matroska::MatroskaTag, size::EbmlSize, Master};
 use anyhow::{bail, Result};
-use std::io::Write;
+use std::io::{Seek, Write};
 
-pub struct EbmlWriter {
-    inner: Box<dyn Write>,
+pub struct EbmlWriter<W> {
+    inner: W,
     position: usize,
 }
 
-impl EbmlWriter {
-    pub fn new<T: Write + 'static>(inner: T, position: usize) -> Self {
-        Self {
-            inner: Box::new(inner),
-            position,
-        }
+impl<W: Write> EbmlWriter<W> {
+    pub fn new(inner: W, position: usize) -> Self {
+        Self { inner, position }
     }
 
     pub fn write(&mut self, data: &[u8]) -> Result<()> {
@@ -66,18 +63,9 @@ impl EbmlWriter {
         if i > (1 << 56) - 1 {
             bail!("vint does not fit");
         }
-        self.write_vint_len(i, Self::vint_length(i))
-    }
-    pub fn vint_length(v: u64) -> usize {
-        let mut len = 1;
-        while len <= 8 {
-            if v < (1 << ((7 * len) - 1)) {
-                break;
-            }
-            len += 1;
-        }
-        len
+        self.write_vint_len(i, vint_length(i))
     }
+
     pub fn write_vint_len(&mut self, i: u64, len: usize) -> Result<()> {
         let mut bytes = i.to_be_bytes();
         let trunc = &mut bytes[(8 - len)..];
@@ -86,6 +74,12 @@ impl EbmlWriter {
     }
 }
 
+impl<W: Seek> Seek for EbmlWriter<W> {
+    fn seek(&mut self, pos: std::io::SeekFrom) -> std::io::Result<u64> {
+        self.inner.seek(pos)
+    }
+}
+
 impl MatroskaTag {
     pub fn write_full(&self, w: &mut Vec<u8>) -> Result<()> {
         let mut buf = vec![];
@@ -97,6 +91,17 @@ impl MatroskaTag {
     }
 }
 
+pub fn vint_length(v: u64) -> usize {
+    let mut len = 1;
+    while len <= 8 {
+        if v < (1 << ((7 * len) - 1)) {
+            break;
+        }
+        len += 1;
+    }
+    len
+}
+
 pub trait WriteValue {
     fn write_to(&self, w: &mut Vec<u8>) -> Result<()>;
 }