use anyhow::Result;
use std::io::Write as _;
use std::process::Command;
use std::sync::OnceLock;
use std::time::Duration;
use crate::codegen::{self, Slot};
use crate::eval::{Eval, Evaluator};
use crate::proc;
use crate::session::Session;
use crate::ui::Ui;
pub enum Action {
Continue,
Quit,
Prefill(String),
}
fn format_c(src: &str) -> String {
static CLANG_FORMAT: OnceLock<Option<std::path::PathBuf>> = OnceLock::new();
let Some(path) = CLANG_FORMAT.get_or_init(|| which::which("clang-format").ok()) else {
return src.to_string();
};
let run = || -> std::io::Result<String> {
let mut cmd = Command::new(path);
cmd.arg("-style={BasedOnStyle: LLVM, IndentWidth: 4}");
let out = proc::run_with_input(&mut cmd, Duration::from_secs(3), src.as_bytes())?;
if out.status.is_some_and(|st| st.success()) && !out.stdout_truncated {
Ok(String::from_utf8_lossy(&out.stdout).into_owned())
} else {
Err(std::io::Error::other("clang-format failed or timed out"))
}
};
run().unwrap_or_else(|_| src.to_string())
}
fn format_duration(d: std::time::Duration) -> String {
let secs = d.as_secs_f64();
if secs < 1e-6 {
format!("{} ns", d.as_nanos())
} else if secs < 1e-3 {
format!("{:.2} µs", secs * 1e6)
} else if secs < 1.0 {
format!("{:.2} ms", secs * 1e3)
} else {
format!("{:.2} s", secs)
}
}
fn edit_input(args: &[&str], session: &Session) -> std::result::Result<Option<String>, String> {
match args {
[] => Ok(session.last_input().map(str::to_string)),
[number] => {
let number = number
.parse::<usize>()
.map_err(|_| "usage: %edit [input-number]".to_string())?;
session
.input(number)
.map(str::to_string)
.map(Some)
.ok_or_else(|| format!("no C input In[{number}]"))
}
_ => Err("usage: %edit [input-number]".to_string()),
}
}
const HELP: &str = "Commands:
%help [--verbose] show commands; --verbose adds usage notes
%quit / %exit quit (Ctrl-D works too)
%clear clear the screen without changing the session
%reset clear the session and start fresh
%src [--raw] show user C; --raw includes generated runtime/protocol
%header list the headers included in every program
%edit [n] copy latest or In[n] into the prompt for editing
%type <expression> query an expression's type without evaluating it
%time <code...> time the execution of a statement or expression once
%timeit <code...> benchmark a statement or expression over multiple loops
%undo undo the most recent retained state change
%cc [path] show or switch the C compiler
%std [std] show or switch the language standard (c11/c17/c23);
%std default returns to the compiler's own default";
const HELP_NOTES: &str = "Notes:
A bare expression prints its value; a trailing ';' runs it silently.
A completed if waits for a blank continuation line; type else / else if
there instead to continue it. Other closed blocks submit immediately, but
a struct/union/enum definition waits for its mandatory trailing ';'.
Function definitions, #include and typedef go to file scope automatically.
%edit n can reopen any C In[n] from this session, including a failed one;
it only fills the next prompt. Modify it and press Enter to submit it under
a new number; the original numbered input remains unchanged.
c-shell supplies main(); enter its body as statements and omit final return.
Redeclaring a local opens a nested shadowing scope. Redefining a function
or type replaces the prior file-scope input only if the compiler accepts
the complete rewritten session; functions are never demoted into main.
%type uses _Generic matching: scalar types and scalar pointers are named;
complete named structs/unions report e.g. Struct Point or Union Value;
simple anonymous typedefs use the typedef name. Other aliases and top-level
qualifiers are canonicalized, and arrays/functions undergo their normal
expression conversions.
%time evaluates an expression or statement once, displays its output/value,
and reports wall-clock execution time. Side effects are retained in session.
%timeit benchmarks an expression or statement in an auto-ranged loop over
multiple runs without modifying the session state.
Struct values use designated members; nested known structs and arrays
expand, but pointer members are shown only as addresses or NULL. Use an
explicit member expression (p.name) or dereference (*ptr) to drill down.
Arrays print their elements, one or two dimensions deep, bounded at 100 per
dimension; a real pointer still prints as an address, and elements with no
printer of their own show <unprintable>.
Pure bare expressions (x + 1, sizeof(int)) are evaluated and forgotten.
Statements and bare expressions that may have effects are kept.
Direct scanf calls record one private input line per dynamic request; later
replay uses that tape, including calls in functions and loops. Other known
file/input/process APIs warn because their external effects may repeat.";
pub fn handle(line: &str, session: &mut Session, ev: &mut Evaluator, ui: &Ui) -> Result<Action> {
let body = line.trim().trim_start_matches('%');
let mut parts = body.split_whitespace();
let cmd = parts.next().unwrap_or("");
let rest: Vec<&str> = parts.collect();
let tail = body.get(cmd.len()..).unwrap_or("").trim();
match cmd {
"help" | "h" | "?" => match rest.as_slice() {
[] => println!("{HELP}"),
[flag] if *flag == "--verbose" => println!(
"{HELP}
{HELP_NOTES}"
),
_ => println!("{}", ui.err("usage: %help [--verbose]")),
},
"quit" | "exit" | "q" => return Ok(Action::Quit),
"clear" => {
print!("[2J[H");
let _ = std::io::stdout().flush();
}
"reset" => {
session.reset();
println!("{}", ui.dim("session cleared"));
}
"undo" => {
if session.undo().is_some() {
println!("{}", ui.dim("undo successful"));
} else {
println!("{}", ui.err("nothing to undo"));
}
}
"header" | "headers" => {
println!(
"{}",
ui.dim("Included in every program (no #include needed):")
);
print!("{}", codegen::HEADERS);
}
"src" => match rest.as_slice() {
[] => println!("{}", format_c(&codegen::build_user_view(session))),
[flag] if *flag == "--raw" => {
let prog = codegen::build(session, "", Slot::Stmt);
println!("{}", format_c(&prog.src));
}
_ => println!("{}", ui.err("usage: %src [--raw]")),
},
"edit" => match edit_input(&rest, session) {
Ok(Some(input)) => return Ok(Action::Prefill(input)),
Ok(None) => println!("{}", ui.dim("nothing to edit")),
Err(message) => println!("{}", ui.err(&message)),
},
"type" => {
if tail.is_empty() {
println!("{}", ui.err("usage: %type <expression>"));
} else {
match ev.type_of(session, tail)? {
Eval::CompileError(diag) => println!("{}", ui.err(diag.trim_end())),
Eval::Done(o) => {
if o.streamed_output_needs_newline {
println!();
}
if !o.warnings.trim().is_empty() {
println!("{}", ui.warn(o.warnings.trim_end()));
}
if !o.output.is_empty() {
print!("{}", o.output);
if !o.output.ends_with('\n') {
println!();
}
}
if !o.errors.is_empty() {
print!("{}", ui.err(&o.errors));
}
if let Some(msg) = o.abnormal {
println!("{}", ui.err(&msg));
} else if let Some(name) = o.value {
println!("{name}");
} else {
println!("{}", ui.err("type query produced no result"));
}
}
}
}
}
"time" => {
if tail.is_empty() {
println!("{}", ui.err("usage: %time <expression or statement>"));
} else {
let n = session.counter + 1;
session.counter = n;
session.remember_input(n, tail);
match ev.eval(session, tail)? {
Eval::CompileError(diag) => println!("{}", ui.err(diag.trim_end())),
Eval::Done(o) => {
if o.streamed_output_needs_newline {
println!("{}", ui.inserted_newline_marker());
}
let note = |s: &str| println!("{}", ui.dim(s));
if o.rewritten.is_some() {
note("(missing semicolon added automatically)");
}
if !o.warnings.trim().is_empty() {
println!("{}", ui.warn(o.warnings.trim_end()));
}
if !o.errors.is_empty() {
print!("{}", ui.err(&o.errors));
}
if let Some(v) = &o.value {
println!("{}{}", ui.out_label(n), v);
}
let committed = o.rewritten.clone().unwrap_or_else(|| tail.to_string());
match &o.abnormal {
Some(msg) => {
println!("{}", ui.err(msg));
note("(input not kept in the session)");
}
None => {
if let Some(index) = o.file_replacement {
session.replace_file(index, &committed);
} else if o.scoped_rebind {
session.commit_scoped(&committed);
} else {
session.commit(&committed, o.slot);
}
session.attach_stdin_events(o.stdin_events.clone());
}
}
println!(
"{}",
ui.dim(&format!("Wall time: {}", format_duration(o.duration)))
);
}
}
}
}
"timeit" => {
if tail.is_empty() {
println!("{}", ui.err("usage: %timeit <expression or statement>"));
} else {
match ev.timeit(session, tail)? {
Eval::CompileError(diag) => println!("{}", ui.err(diag.trim_end())),
Eval::Done(o) => {
if o.streamed_output_needs_newline {
println!("{}", ui.inserted_newline_marker());
}
if let Some(msg) = o.abnormal {
println!("{}", ui.err(&msg));
} else if let Some(report) = o.value {
println!("{report}");
}
}
}
}
}
"cc" => {
if rest.is_empty() {
println!("{}", ev.tc.describe());
} else {
let std = ev.tc.std.clone();
let std_opt = if std.is_empty() {
None
} else {
Some(std.as_str())
};
match crate::toolchain::Toolchain::detect(Some(rest[0]), std_opt) {
Ok(tc) => {
ev.set_toolchain(tc);
println!("{}", ev.tc.describe());
}
Err(e) => println!("{}", ui.err(&format!("{e}"))),
}
}
}
"std" => {
if rest.is_empty() {
println!("{}", ev.tc.describe());
} else {
let want = rest[0].trim_start_matches("-std=");
let req = if want == "default" { None } else { Some(want) };
let path = ev.tc.path.display().to_string();
match crate::toolchain::Toolchain::detect(Some(&path), req) {
Ok(new) if req.is_none() || new.std == want => {
ev.set_toolchain(new);
println!("{}", ev.tc.describe());
}
_ => println!(
"{}",
ui.err(&format!("this compiler does not support -std={want}"))
),
}
}
}
other => println!(
"{}",
ui.err(&format!("unknown command %{other} — try %help"))
),
}
Ok(Action::Continue)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn edit_resolves_latest_and_numbered_inputs_without_mutating_them() {
let mut session = Session::default();
assert_eq!(edit_input(&[], &session).expect("empty lookup"), None);
session.remember_input(1, "int value = 1;");
session.remember_input(2, "value + 1");
assert_eq!(
edit_input(&[], &session).expect("latest lookup").as_deref(),
Some("value + 1")
);
assert_eq!(
edit_input(&["1"], &session)
.expect("numbered lookup")
.as_deref(),
Some("int value = 1;")
);
assert_eq!(
edit_input(&["7"], &session).expect_err("missing lookup"),
"no C input In[7]"
);
}
}