feat: Add cleanup_mapping_file function

src/lib.rs

@@ -42,7 +42,7 @@ mod stacktrace;
 
 pub use mapper::{DeobfuscatedSignature, ProguardMapper, RemappedFrameIter};
 pub use mapping::{
-    LineMapping, MappingSummary, ParseError, ParseErrorKind, ProguardMapping, ProguardRecord,
-    ProguardRecordIter,
+    cleanup_mapping_file, LineMapping, MappingSummary, ParseError, ParseErrorKind, ProguardMapping,
+    ProguardRecord, ProguardRecordIter,
 };
 pub use stacktrace::{StackFrame, StackTrace, Throwable};

src/mapping.rs

@@ -4,6 +4,7 @@
 //! [here](https://www.guardsquare.com/en/products/proguard/manual/retrace).
 
 use std::fmt;
+use std::io::{BufRead, Write};
 use std::str;
 
 #[cfg(feature = "uuid")]
@@ -206,16 +207,15 @@ impl<'s> ProguardMapping<'s> {
     /// assert_eq!(without.has_line_info(), false);
     /// ```
     pub fn has_line_info(&self) -> bool {
-        // We are matching on the inner `ProguardRecord` anyway
-        #[allow(clippy::manual_flatten)]
-        for record in self.iter() {
-            if let Ok(ProguardRecord::Method { line_mapping, .. }) = record {
-                if line_mapping.is_some() {
-                    return true;
-                }
-            }
-        }
-        false
+        self.iter().any(|record| {
+            matches!(
+                record,
+                Ok(ProguardRecord::Method {
+                    line_mapping: Some(_),
+                    ..
+                })
+            )
+        })
     }
 
     /// Calculates the UUID of the mapping file.
@@ -690,8 +690,45 @@ fn is_newline(byte: &u8) -> bool {
     *byte == b'\r' || *byte == b'\n'
 }
 
+/// Cleans up a Proguard mapping file by removing all records
+/// that can't be used by a [`ProguardMapper`].
+///
+/// This preserves class, method, and "sourceFile" header records.
+/// It removes field and all other header records, as well as all invalid lines.
+pub fn cleanup_mapping_file<R, W>(mut source: R, mut output: W) -> Result<(), std::io::Error>
+where
+    R: BufRead,
+    W: Write,
+{
+    let mut line_buf = String::new();
+    loop {
+        line_buf.clear();
+        let read = source.read_line(&mut line_buf)?;
+
+        if read == 0 {
+            break;
+        }
+
+        let (record, _rest) = parse_proguard_record(line_buf.as_bytes());
+        if matches!(
+            record,
+            Ok(ProguardRecord::Class { .. }
+                | ProguardRecord::Method { .. }
+                | ProguardRecord::Header {
+                    key: "sourceFile",
+                    ..
+                })
+        ) {
+            output.write_all(line_buf.as_bytes())?;
+        }
+    }
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
+    use std::io::Cursor;
+
     use super::*;
 
     #[test]
@@ -1060,4 +1097,32 @@ androidx.activity.OnBackPressedCallback
             ],
         );
     }
+
+    #[test]
+    fn cleanup() {
+        let bytes = br#"
+# compiler: R8
+# common_typos_disable
+
+androidx.activity.OnBackPressedCallback->c.a.b:
+androidx.activity.OnBackPressedCallback -> c.a.b:
+# {"id":"sourceFile","fileName":"Test.kt"}
+    boolean mEnabled -> a
+  boolean mEnabled -> a
+    java.util.ArrayDeque mOnBackPressedCallbacks -> b
+    1:4:void onBackPressed():184:187 -> c
+androidx.activity.OnBackPressedCallback 
+-> c.a.b:
+        "#;
+
+        let mut out = Vec::new();
+
+        cleanup_mapping_file(&mut Cursor::new(bytes), &mut out).unwrap();
+
+        let expected = br#"androidx.activity.OnBackPressedCallback -> c.a.b:
+# {"id":"sourceFile","fileName":"Test.kt"}
+    1:4:void onBackPressed():184:187 -> c
+"#;
+        assert_eq!(out, expected);
+    }
 }