4. Explore C++ code intelligence

Sense’s integration with pw_ide enables fast and accurate code navigation, autocompletion based on a deep understanding of the code structure, and instant compiler warnings and errors. Try intelligent code navigation features now:

Navigate the code intelligently

Imagine this hypothetical development scenario. Suppose that you need to modify how your app logs messages. Your first task is to understand how logging currently works on the Pico 1. You know that your app uses pw_log and that pw_log uses a special type of API called a facade where the implementation can be changed during compilation. The plan is to use the intelligent code navigation features of pw_ide to determine the true, final implementation of the logging functions used in your project.

VS Code

1. Press Control+Shift+P (Command+Shift+P on macOS) to open the Command Palette.

2. Start typing Pigweed: Select Code Analysis Target and press Enter to start executing that command.

   

   Tip

   You can also select code analysis targets from the bottom-left of your VS Code GUI, in the status bar. In the next image, the mouse cursor (bottom-left of image) is hovering over the GUI element for selecting code analysis targets.

   

3. Select the rp2040 option.

   The code intelligence is now set up to help you with physical Pico 1 programming. The RP2040 is the microprocessor that powers the Pico 1. If you had selected the other option, host_simulator, the code intelligence would be set up to help with programming the simulated app that you will run on your development host later. Code intelligence for the Pico 2 (rp2350) isn’t supported yet. rp2040 represents one platform, host_simulator another.

   We will verify the platform-specific code intelligence now by making sure that pw_log invocations resolve to different backends. This will make more sense after you do the hands-on demonstration.

4. Open //apps/blinky/main.cc.

   

5. Right-click the PW_LOG_INFO() invocation and select Go to Definition.

   

   This should take you to a file called log.h Your cursor should be on the line that defines PW_LOG_INFO:

   #ifndef PW_LOG_INFO
   #define PW_LOG_INFO(...) \  // Your cursor should be on this line.
     PW_LOG(PW_LOG_LEVEL_INFO, PW_LOG_MODULE_NAME, PW_LOG_FLAGS, __VA_ARGS__)
   #endif  // PW_LOG_INFO
   

6. Right-click the PW_LOG() invocation (on the line below your cursor) and select Go to Definition again.

   Your cursor should jump to the line that defines PW_LOG:

   // Your cursor should be on the next line.
   #define PW_LOG(                                                            \
       level, verbosity, module, flags, /* format string and arguments */...) \
     do {                                                                     \
       if (PW_LOG_ENABLE_IF(level, verbosity, module, flags)) {               \
         PW_HANDLE_LOG(level, module, flags, __VA_ARGS__);                    \
       }                                                                      \
     } while (0)
   

7. Finally, right-click the PW_HANDLE_LOG() invocation and select Go to Definition one last time. You should jump to a pw_log_tokenized backend header. You can hover over the filename in the tab (log_backend.h) to see the full path to the header.

8. Open the Command Palette, switch your target to host_simulator, and then repeat this workflow again, starting from the PW_LOG_INFO invocation in //apps/blinky/main.cc. You should see the definitions finally resolve to a pw_log_string backend header.

CLI

This feature is only supported in VS Code.

Explanation

When you set your platform to rp2040 and followed the call to PW_LOG_INFO() in //apps/blinky/main.cc back to its source, you ended on a header within pw_log_tokenized. When you repeated the process a second time with the host_simulator platform you ended on a header in a different module, pw_log_string. This proves that intelligent code navigation is working. The pw_log API is a facade. It’s implementation is swapped out during compilation depending on what platform you’re building for. The rp2040 platform has been set up to use the pw_log_tokenized implementation, whereas the host_simulator platform uses the pw_log_string implementation.

Here’s a diagram summary of how the intelligent code navigation resolved to different files depending on the code analysis target you selected:

flowchart LR a["main.cc"] --> b["log.h"] b["log.h"] -. rp2040 .-> c["pw_log_tokenized/.../log_backend.h"] b["log.h"] -. host_simulator .-> d["pw_log_string/.../log_backend.h"]

Summary

Portable, hardware-agnostic software abstractions such as pw_log make it easier to reuse code across projects and hardware platforms. But they also make it more difficult to correctly navigate references in your codebase. The Pigweed extension for VS Code can solve this problem; you just need to tell it what hardware platform within your codebase to focus on.

Next, head over to 5. Run host tests to learn how to run unit tests on your development host.