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/*
* Mitts Build — Rust-first build and package tooling with shared artifact cache
* Copyright (c) 2026 Alexander Panasenko
*
* Contact: alex@prod.codes
* Author: https://prod.codes/about/
* Project: https://github.com/alex09x/mitts
* SPDX-License-Identifier: MIT OR Apache-2.0
*/
use super::types::EnvMacroDiscovery;
use super::unescape::unescape_rust_string;
use std::fs;
use std::path::Path;
/// Skips whitespace, line comments (//...), and block comments (/*...*/) including nested block comments.
fn skip_trivia(source: &str, mut pos: usize) -> usize {
let len = source.len();
while pos < len {
if source[pos..].starts_with("//") {
pos += 2;
while pos < len {
if let Some(ch) = source[pos..].chars().next() {
pos += ch.len_utf8();
if ch == '\n' {
break;
}
} else {
break;
}
}
} else if source[pos..].starts_with("/*") {
pos += 2;
let mut depth = 1;
while pos < len && depth > 0 {
if source[pos..].starts_with("/*") {
depth += 1;
pos += 2;
} else if source[pos..].starts_with("*/") {
depth -= 1;
pos += 2;
} else if let Some(ch) = source[pos..].chars().next() {
pos += ch.len_utf8();
} else {
break;
}
}
} else if let Some(ch) = source[pos..].chars().next() {
if ch.is_whitespace() {
pos += ch.len_utf8();
} else {
break;
}
} else {
break;
}
}
pos
}
/// Scans Rust source code for compile-time env!("VAR") and option_env!("VAR") invocations.
/// Advances strictly by UTF-8 character boundaries to prevent panicking on non-ASCII code.
pub fn scan_env_macros(source: &str) -> EnvMacroDiscovery {
let len = source.len();
let mut i = 0;
let mut vars = Vec::new();
while i < len {
// 1. Skip line comments
if source[i..].starts_with("//") {
i += 2;
while i < len {
if let Some(ch) = source[i..].chars().next() {
i += ch.len_utf8();
if ch == '\n' {
break;
}
} else {
break;
}
}
continue;
}
// 2. Skip block comments (handling nested comments)
if source[i..].starts_with("/*") {
i += 2;
let mut depth = 1;
while i < len && depth > 0 {
if source[i..].starts_with("/*") {
depth += 1;
i += 2;
} else if source[i..].starts_with("*/") {
depth -= 1;
i += 2;
} else if let Some(ch) = source[i..].chars().next() {
i += ch.len_utf8();
} else {
break;
}
}
continue;
}
// 3. Skip raw strings: r#"..."# or r"..."
let raw_prefix = if source[i..].starts_with("r#") || source[i..].starts_with("r\"") {
Some(1)
} else if source[i..].starts_with("br#")
|| source[i..].starts_with("br\"")
|| source[i..].starts_with("cr#")
|| source[i..].starts_with("cr\"")
{
Some(2)
} else {
None
};
if let Some(pref_len) = raw_prefix {
let rest = &source[i + pref_len..];
let mut hashes = 0;
while rest[hashes..].starts_with('#') {
hashes += 1;
}
if rest[hashes..].starts_with('"') {
let content_start = i + pref_len + hashes + 1;
let closing = format!("\"{}", "#".repeat(hashes));
if let Some(pos) = source[content_start..].find(&closing) {
i = content_start + pos + closing.len();
continue;
} else {
break;
}
}
}
// 4. Skip normal string literals: "..." (or b"...", c"...")
let str_prefix = if source[i..].starts_with('"') {
Some(1)
} else if source[i..].starts_with("b\"") || source[i..].starts_with("c\"") {
Some(2)
} else {
None
};
if let Some(pref_len) = str_prefix {
i += pref_len;
let mut escaped = false;
while i < len {
if let Some(ch) = source[i..].chars().next() {
i += ch.len_utf8();
if escaped {
escaped = false;
} else if ch == '\\' {
escaped = true;
} else if ch == '"' {
break;
}
} else {
break;
}
}
continue;
}
// 5. Check for compile-time env! or option_env! invocation
let (ident_len, is_macro_ident) = if source[i..].starts_with("option_env") {
let next_ch = source[i + 10..].chars().next();
let is_ident_boundary = next_ch
.map(|c| !c.is_alphanumeric() && c != '_')
.unwrap_or(true);
(10, is_ident_boundary)
} else if source[i..].starts_with("env") {
let next_ch = source[i + 3..].chars().next();
let is_ident_boundary = next_ch
.map(|c| !c.is_alphanumeric() && c != '_')
.unwrap_or(true);
(3, is_ident_boundary)
} else {
(0, false)
};
if is_macro_ident {
if i > 0 {
if let Some(prev) = source[..i].chars().next_back() {
if prev.is_alphanumeric() || prev == '_' {
i += ident_len;
continue;
}
}
}
let after_ident = i + ident_len;
let bang_pos = skip_trivia(source, after_ident);
if bang_pos < len
&& source[bang_pos..].starts_with('!')
&& !source[bang_pos..].starts_with("!=")
{
let delim_pos = skip_trivia(source, bang_pos + 1);
if delim_pos < len {
let delim = source[delim_pos..].chars().next();
if delim == Some('(') || delim == Some('[') || delim == Some('{') {
let mut j = delim_pos + 1;
j = skip_trivia(source, j);
if source[j..].starts_with('"') {
j += 1;
let str_start = j;
let mut escaped = false;
let mut str_end = None;
while j < len {
if let Some(ch) = source[j..].chars().next() {
j += ch.len_utf8();
if escaped {
escaped = false;
} else if ch == '\\' {
escaped = true;
} else if ch == '"' {
str_end = Some(j - 1);
break;
}
} else {
break;
}
}
if let Some(end) = str_end {
let raw_token = &source[str_start..end];
if let Some(unescaped) = unescape_rust_string(raw_token) {
vars.push(unescaped);
i = j;
continue;
} else {
return EnvMacroDiscovery::UntrackedDynamic;
}
} else {
return EnvMacroDiscovery::UntrackedDynamic;
}
} else if source[j..].starts_with("r#") || source[j..].starts_with("r\"") {
let pref_len = 1;
let rest = &source[j + pref_len..];
let mut hashes = 0;
while rest[hashes..].starts_with('#') {
hashes += 1;
}
if rest[hashes..].starts_with('"') {
let content_start = j + pref_len + hashes + 1;
let closing = format!("\"{}", "#".repeat(hashes));
if let Some(pos) = source[content_start..].find(&closing) {
let raw_token = &source[content_start..content_start + pos];
vars.push(raw_token.to_string());
i = content_start + pos + closing.len();
continue;
} else {
return EnvMacroDiscovery::UntrackedDynamic;
}
} else {
return EnvMacroDiscovery::UntrackedDynamic;
}
} else {
return EnvMacroDiscovery::UntrackedDynamic;
}
}
}
}
}
if let Some(ch) = source[i..].chars().next() {
i += ch.len_utf8();
} else {
break;
}
}
vars.sort();
vars.dedup();
EnvMacroDiscovery::Tracked(vars)
}
/// Recursively scans a package directory for compile-time env!/option_env! usages across all .rs files.
pub fn discover_package_env_macros(package_dir: &Path) -> (EnvMacroDiscovery, Vec<String>) {
let mut all_vars = Vec::new();
let mut stack = vec![package_dir.to_path_buf()];
while let Some(dir) = stack.pop() {
if let Ok(entries) = fs::read_dir(&dir) {
for entry in entries.flatten() {
let path = entry.path();
let fname = entry.file_name();
let fname_str = fname.to_string_lossy();
if path.is_dir() {
if fname_str == "target" || fname_str == ".mitts" || fname_str == ".git" {
continue;
}
stack.push(path);
} else if path.is_file() && fname_str.ends_with(".rs") {
if let Ok(content) = fs::read_to_string(&path) {
let scan_result = std::panic::catch_unwind(|| scan_env_macros(&content));
match scan_result {
Ok(EnvMacroDiscovery::Tracked(vars)) => {
all_vars.extend(vars);
}
Ok(EnvMacroDiscovery::UntrackedDynamic) | Err(_) => {
return (EnvMacroDiscovery::UntrackedDynamic, Vec::new());
}
}
}
}
}
}
}
all_vars.sort();
all_vars.dedup();
(EnvMacroDiscovery::Tracked(all_vars.clone()), all_vars)
}
#[cfg(test)]
#[path = "env_macro_tests.rs"]
mod tests;