Backward Search in CLI (hashtag2725)

[vikramsubramanian]

In Mac, when you press control+r, you can do backward search. This is very handy. Not sure of the shortcut in mac and linux but let's implement this across all platforms. )

[mayil-ai[bot]]

We're not sure how to solve this one.

but here are some ideas that might help you get started -

Summary: Implement backward search functionality in CLI for all platforms.

Implementation ideas

To implement backward search in the CLI similar to the control+r functionality in Unix-like systems, you can follow these steps:

• Define a new key action for backward search, e.g., CTRL_R.
• Add a case for CTRL_R in the switch statement that handles key actions.
• Implement the backward search functionality by maintaining a search buffer and iterating through the command history to find the most recent match.
• Update the display to show the current match and allow the user to continue typing to refine the search.

Here's a high-level overview of the implementation:

1. Define the CTRL_R key action in the enum KEY_ACTION:

enum KEY_ACTION {
    // ... existing key actions ...
    CTRL_R = 18,    /* Ctrl+r */
};

2. Add a case for CTRL_R in the switch statement:

case CTRL_R: /* ctrl+r, initiate backward search */
    linenoiseEditInitiateBackwardSearch(&l);
    break;

3. Implement the linenoiseEditInitiateBackwardSearch function:

static void linenoiseEditInitiateBackwardSearch(struct linenoiseState* l) {
    std::string searchBuffer;
    int historyIndex = history_len - 1; // Start from the end of the history

    // Display search prompt
    printf("(reverse-i-search)`': ");
    fflush(stdout);

    // Handle input characters for search
    while (true) {
        char c;
        if (read(l->ifd, &c, 1) <= 0) {
            // Handle read error or EOF
            break;
        }

        switch (c) {
            case CTRL_H: // Backspace, remove last character from searchBuffer
                if (!searchBuffer.empty()) {
                    searchBuffer.pop_back();
                    printf("\b \b"); // Erase last character from terminal
                    fflush(stdout);
                }
                break;
            case ENTER: // Finalize search
                // Set the current line to the found history entry
                strncpy(l->buf, history[historyIndex], l->buflen);
                l->len = l->pos = strlen(l->buf);
                refreshLine(l);
                return;
            default: // Add character to searchBuffer and update search
                searchBuffer += c;
                printf("%c", c); // Echo character to terminal
                fflush(stdout);
                // Perform search in history
                for (; historyIndex >= 0; --historyIndex) {
                    if (strstr(history[historyIndex], searchBuffer.c_str())) {
                        // Found a match, display it
                        printf("\r(reverse-i-search)`%s': %s", searchBuffer.c_str(), history[historyIndex]);
                        fflush(stdout);
                        break;
                    }
                }
                break;
        }
    }
}

4. Make sure to handle the case where no match is found and allow the user to cancel the search with a key like CTRL_C.

5. Update the refreshLine function if necessary to handle the display of the search prompt and the current match.

This is a high-level overview and the actual implementation may require additional error handling, edge case checks, and integration with the existing codebase. The read function and terminal output (printf) are used for simplicity, but you may need to use more sophisticated I/O handling depending on the project's requirements.

Code snippets to check

• tools/shell/linenoise.cpp

  This file contains the key bindings for the shell, which is where the backward search functionality would be implemented.

• tools/shell/linenoise.cpp

  This snippet shows existing key bindings and is a logical place to add a new key binding for backward search.

• tools/shell/linenoise.cpp

  This snippet defines the enum for key actions, which would need to be updated to include a new key binding for backward search.