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| author | A Farzat <a@farzat.xyz> | 2026-03-07 21:50:56 +0300 |
|---|---|---|
| committer | A Farzat <a@farzat.xyz> | 2026-03-07 21:50:56 +0300 |
| commit | c181afaf936ba0d5cd19c38869422fc9351af2d1 (patch) | |
| tree | a8361f6c40bfa0f4d4883a89dc418ece5b1ce8fc | |
| parent | a1ffe295ade3026f8712c2608eacc285c595f08c (diff) | |
| download | oreilly-epub-c181afaf936ba0d5cd19c38869422fc9351af2d1.tar.gz oreilly-epub-c181afaf936ba0d5cd19c38869422fc9351af2d1.zip | |
Avoid using string buffers when modifying chapters
This saves on memory. Bytes are read from the file as needed, and
written to zip as soon as they are ready.
| -rw-r--r-- | src/epub.rs | 13 | ||||
| -rw-r--r-- | src/xml.rs | 62 |
2 files changed, 41 insertions, 34 deletions
diff --git a/src/epub.rs b/src/epub.rs index f9a5aac..c455671 100644 --- a/src/epub.rs +++ b/src/epub.rs @@ -8,7 +8,7 @@ use relative_path::{RelativePath, RelativePathBuf}; use reqwest::Client; use std::{ collections::HashMap, - io::{Read, Write}, + io::{BufReader, Read, Write}, path::Path, }; use tokio::{ @@ -107,21 +107,20 @@ pub fn create_epub_archive( for entry in file_entries { zip.start_file(&entry.full_path, options)?; let mut src_file = std::fs::File::open(entry.full_path.to_path(epub_root))?; - let mut buffer = Vec::new(); - src_file.read_to_end(&mut buffer)?; if let Some(chapter) = chapters.get(&entry.ourn) { let chapter_dir = entry.full_path.parent().unwrap_or(RelativePath::new("")); - let html = String::from_utf8(buffer)?; - let html = build_epub_chapter( + build_epub_chapter( epub_data, chapter, chapter_dir, - &html, + BufReader::new(src_file), &url_to_file, &url_path_to_local, + &mut zip, )?; - zip.write_all(html.as_bytes())?; } else { + let mut buffer = Vec::new(); + src_file.read_to_end(&mut buffer)?; zip.write_all(&buffer)?; } } @@ -4,7 +4,7 @@ use quick_xml::events::{BytesStart, Event}; use quick_xml::{Reader, Writer}; use relative_path::{RelativePath, RelativePathBuf}; use std::collections::HashMap; -use std::io::Cursor; +use std::io::{BufRead, Write}; use url::Url; use crate::models::{Chapter, EpubResponse, FileEntry}; @@ -31,25 +31,50 @@ fn is_html_void_tag(name: &[u8]) -> bool { } /// Processes the fragment and outputs a complete, EPUB-ready XHTML document. -pub fn build_epub_chapter( +pub fn build_epub_chapter<R: BufRead, W: Write>( epub_data: &EpubResponse, chapter: &Chapter, chapter_dir: &RelativePath, - fragment: &str, + fragment_input: R, url_to_file: &HashMap<&Url, &FileEntry>, url_path_to_local: &HashMap<&str, &RelativePathBuf>, -) -> Result<String> { + mut out: &mut W, +) -> Result<()> { + // EPUB XHTML Boilerplate wrapper. + // EPUBs strictly require the w3 and idpf namespaces to validate properly. + let wrapper_xhtml = xml!( + <?xml version="1.0" encoding="UTF-8"?> + <html xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops" + lang={epub_data.language} xml:lang={epub_data.language}> + <head> + <title>{chapter.title}</title> + {|doc| make_stylesheet_links(doc, chapter, chapter_dir, url_to_file)} + </head> + <body> + </body> + </html> + ); + let wrapper_suffix = "</body></html>"; + let wrapper_prefix = wrapper_xhtml + .as_str() + .strip_suffix(wrapper_suffix) + .context("Wrapper must end with </body></html>")?; + + // Write wrapper prefix to output first. + out.write_all(wrapper_prefix.as_bytes())?; + // Setup the XML Reader and Writer. - let mut reader = Reader::from_str(fragment); + let mut reader = Reader::from_reader(fragment_input); // Preserve spacing for EPUB text formatting. reader.config_mut().trim_text(false); // Fragments could have unmatched tags - tell the parser not to panic if so. reader.config_mut().check_end_names = false; - let mut writer = Writer::new(Cursor::new(Vec::new())); + let mut writer = Writer::new(&mut out); // Loop through the XML events and rewrite tags. + let mut buffer = Vec::new(); loop { - match reader.read_event() { + match reader.read_event_into(&mut buffer) { Ok(Event::Start(tag_data)) => { // If it is a void tag, convert it to a self-closing XML tag. let tag_type = if is_html_void_tag(tag_data.name().as_ref()) { @@ -83,27 +108,10 @@ pub fn build_epub_chapter( } } - // Extract the modified fragment - let processed_fragment = String::from_utf8(writer.into_inner().into_inner())?; - - // Wrap in EPUB XHTML Boilerplate. - // EPUBs strictly require the w3 and idpf namespaces to validate properly. - let wrapper_xhtml = xml!( - <?xml version="1.0" encoding="UTF-8"?> - <html xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops" - lang={epub_data.language} xml:lang={epub_data.language}> - <head> - <title>{chapter.title}</title> - {|doc| make_stylesheet_links(doc, chapter, chapter_dir, url_to_file)} - </head> - <body> - </body> - </html> - ); - let wrapper_suffix = "</body></html>"; - let wrapper_prefix = wrapper_xhtml.as_str().strip_suffix(wrapper_suffix).context("Wrapper must end with </body></html>")?; + // Finish by flushing wrapper suffix to output. + out.write_all(wrapper_suffix.as_bytes())?; - Ok(format!("{}\n{}\n{}", wrapper_prefix, processed_fragment, wrapper_suffix)) + Ok(()) } /// Helper function add link elements for stylesheets to an xml Document. |