Add macos/ios app using rust lib

src/lib.rs

@@ -1,4 +1,8 @@
 mod move_money;
+use std::ffi::c_char;
+use std::ffi::CStr;
+use std::ffi::CString;
+
 pub use self::move_money::*;
 
 mod smush_rules;
@@ -6,3 +10,47 @@ pub use self::smush_rules::*;
 
 mod overhead_allocation;
 pub use self::overhead_allocation::*;
+
+#[no_mangle]
+pub extern "C" fn move_money_from_text(
+    rules: *const c_char,
+    lines: *const c_char,
+    use_numeric_accounts: bool,
+) -> *mut c_char {
+    let mut output_writer = csv::Writer::from_writer(vec![]);
+    let safe_rules = unsafe {
+        assert!(!rules.is_null());
+        CStr::from_ptr(rules)
+    };
+    let safe_lines = unsafe {
+        assert!(!lines.is_null());
+        CStr::from_ptr(lines)
+    };
+    move_money(
+        csv::Reader::from_reader(safe_rules.to_bytes()),
+        csv::Reader::from_reader(safe_lines.to_bytes()),
+        &mut output_writer,
+        use_numeric_accounts,
+    );
+    // TODO: Replace all these unwraps with something more elegant
+    let inner = output_writer.into_inner().unwrap();
+    CString::new(String::from_utf8(inner).unwrap())
+        .unwrap()
+        .into_raw()
+
+    // Also some resources I looked at, in case things aren't going right:
+    // https://notes.huy.rocks/en/string-ffi-rust.html
+    // http://jakegoulding.com/rust-ffi-omnibus/string_return/
+    // https://rust-unofficial.github.io/patterns/idioms/ffi/passing-strings.html
+    // This looks like exactly what I'm doing too: https://mozilla.github.io/firefox-browser-architecture/experiments/2017-09-06-rust-on-ios.htmlcar
+}
+
+#[no_mangle]
+pub extern "C" fn move_money_from_text_free(s: *mut c_char) {
+    unsafe {
+        if s.is_null() {
+            return;
+        }
+        CString::from_raw(s)
+    };
+}