make it easy to resolve symbols by frame

src/capture.rs

@@ -86,6 +86,27 @@ impl Frame {
             } => module_base_address.map(|addr| addr as *mut c_void),
         }
     }
+
+    /// Resolve all addresses in the frame to their symbolic names.
+    fn resolve_symbols(&self) -> Vec<BacktraceSymbol> {
+        let mut symbols = Vec::new();
+        let sym = |symbol: &Symbol| {
+            symbols.push(BacktraceSymbol {
+                name: symbol.name().map(|m| m.as_bytes().to_vec()),
+                addr: symbol.addr().map(|a| a as usize),
+                filename: symbol.filename().map(|m| m.to_owned()),
+                lineno: symbol.lineno(),
+                colno: symbol.colno(),
+            });
+        };
+        match *self {
+            Frame::Raw(ref f) => resolve_frame(f, sym),
+            Frame::Deserialized { ip, .. } => {
+                resolve(ip as *mut c_void, sym);
+            }
+        }
+        symbols
+    }
 }
 
 /// Captured version of a symbol in a backtrace.
@@ -216,27 +237,7 @@ impl Backtrace {
     /// This function requires the `std` feature of the `backtrace` crate to be
     /// enabled, and the `std` feature is enabled by default.
     pub fn resolve(&mut self) {
-        for frame in self.frames.iter_mut().filter(|f| f.symbols.is_none()) {
-            let mut symbols = Vec::new();
-            {
-                let sym = |symbol: &Symbol| {
-                    symbols.push(BacktraceSymbol {
-                        name: symbol.name().map(|m| m.as_bytes().to_vec()),
-                        addr: symbol.addr().map(|a| a as usize),
-                        filename: symbol.filename().map(|m| m.to_owned()),
-                        lineno: symbol.lineno(),
-                        colno: symbol.colno(),
-                    });
-                };
-                match frame.frame {
-                    Frame::Raw(ref f) => resolve_frame(f, sym),
-                    Frame::Deserialized { ip, .. } => {
-                        resolve(ip as *mut c_void, sym);
-                    }
-                }
-            }
-            frame.symbols = Some(symbols);
-        }
+        self.frames.iter_mut().for_each(BacktraceFrame::resolve);
     }
 }
 
@@ -314,6 +315,15 @@ impl BacktraceFrame {
     pub fn symbols(&self) -> &[BacktraceSymbol] {
         self.symbols.as_ref().map(|s| &s[..]).unwrap_or(&[])
     }
+
+    /// Resolve all addresses in the frame to their symbolic names.
+    ///
+    /// If this frame has been previously resolved, this function does nothing.
+    pub fn resolve(&mut self) {
+        if self.symbols.is_none() {
+            self.symbols = Some(self.frame.resolve_symbols());
+        }
+    }
 }
 
 impl BacktraceSymbol {