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use std::fmt;
#[derive(Debug)]
pub enum RenderError {
BinaryFile(String),
}
impl fmt::Display for RenderError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
RenderError::BinaryFile(filename) => {
write!(f, "Binary file encountered: {}", filename)
}
}
}
}
impl std::error::Error for RenderError {}
pub fn render(project_name: &str, files: &[(&str, &[u8])]) -> Result<String, RenderError> {
let mut output = format!("# {}\n", project_name);
if !files.is_empty() {
output.push_str("\n## Files\n");
}
for (filename, bytes) in files {
let content = std::str::from_utf8(bytes)
.map_err(|_| RenderError::BinaryFile(filename.to_string()))?;
let outer_backticks = outer_backticks(content);
output.push_str(&format!(
"\n### {}\n{}\n{}\n{}\n",
filename, outer_backticks, content, outer_backticks
));
}
Ok(output)
}
fn outer_backticks(contents: &str) -> String {
let mut max_ticks = 0;
let mut current_count = 0;
for char in contents.chars() {
if char == '`' {
current_count += 1;
if current_count > max_ticks {
max_ticks = current_count;
}
} else {
current_count = 0;
}
}
let fence_len = std::cmp::max(3, max_ticks + 1);
"`".repeat(fence_len)
}
#[cfg(test)]
mod tests {
use super::{RenderError, render};
#[test]
fn empty_project_renders_only_title() {
let output = render("Project name", &[]);
assert_eq!(output.unwrap(), "# Project name\n");
}
#[test]
fn single_file_is_rendered() {
let files: Vec<(&str, &[u8])> = vec![("main.rs", b"fn main() {}")];
let output = render("Project name", &files);
assert_eq!(
output.unwrap(),
"# Project name\n\n\
## Files\n\n\
### main.rs\n\
```\n\
fn main() {}\n\
```\n"
);
}
#[test]
fn multiple_files_are_rendered_in_order() {
let files: Vec<(&str, &[u8])> = vec![
("main.rs", b"fn main() {}"),
("lib.rs", b"pub fn hello() {}"),
];
let output = render("Project name", &files);
assert_eq!(
output.unwrap(),
"# Project name\n\n\
## Files\n\n\
### main.rs\n\
```\n\
fn main() {}\n\
```\n\n\
### lib.rs\n\
```\n\
pub fn hello() {}\n\
```\n"
);
}
#[test]
fn file_with_backticks_is_handled_safely() {
let files: Vec<(&str, &[u8])> =
vec![("example.rs", b"fn main() { println!(\"``` inside\"); }")];
let output = render("Project name", &files);
assert_eq!(
output.unwrap(),
"# Project name\n\n\
## Files\n\n\
### example.rs\n\
````\n\
fn main() { println!(\"``` inside\"); }\n\
````\n"
);
}
#[test]
fn binary_file_is_rejected() {
let files: Vec<(&str, &[u8])> = vec![("image.png", &[0x00, 0x01, 0x02, 0xc3])];
let result = render("Project name", &files);
assert!(matches!(
result,
Err(RenderError::BinaryFile(name)) if name == "image.png"
));
}
}
|