[PR] Enable completion for both bash and zsh [maven-mvnd]

["janweinschenker (via GitHub)" <gi...@apache.org>]

janweinschenker opened a new pull request, #1514:
URL: https://github.com/apache/maven-mvnd/pull/1514

   # Changes from Bash to Zsh Completion Script
   
   This document outlines the changes made to adapt `mvnd-bash-completion.bash` for zsh compatibility in `mvnd-bash+zsh-completion.sh`. These changes enable the same completion script to work in both bash and zsh shells.
   
   ## Overview
   
   The zsh version of the completion script maintains backward compatibility with bash while adding zsh-specific enhancements. The script auto-detects the shell type and applies the appropriate behavior.
   
   ## Key Changes
   
   ### 1. Shell Detection
   
   A new shell detection mechanism was added at the beginning of the script:
   
   ```shell
   if [ -n "$ZSH_VERSION" ]; then
       __MVND_SHELL="zsh"
   elif [ -n "$BASH_VERSION" ]; then
       __MVND_SHELL="bash"
   else
       __MVND_SHELL="unknown"
   fi
   ```
   
   This allows the script to conditionally execute shell-specific code paths.
   
   ### 2. Zsh Completion System Initialization
   
   A new block initializes the zsh completion system and enables bash compatibility mode:
   
   ```shell
   if __is_zsh; then
       # Enable bash compatibility
       autoload -Uz compinit
       compinit -u 2>/dev/null
   
       # Load bashcompinit for bash-style completions
       autoload -Uz bashcompinit
       bashcompinit
   
       # Set options for better compatibility
       setopt NO_BEEP
       setopt COMPLETE_IN_WORD
       setopt ALWAYS_TO_END
   
       # Define COMP_WORDBREAKS if not set (bash compatibility)
       [[ -z "$COMP_WORDBREAKS" ]] && COMP_WORDBREAKS=$' \t\n"\'><=;|&(:'
   fi
   
   # Check if the current shell is zsh
   __is_zsh()
   {
       [ "$__MVND_SHELL" = "zsh" ]
   }
   ```
   
   Key components:
   
   * `compinit` - Initializes zsh's completion system
   * `bashcompinit` - Enables bash-style completion functions (`complete`, `compgen`, `COMPREPLY`)
   * `setopt` - Sets zsh options for improved completion behavior
   * `COMP_WORDBREAKS` - Defines word break characters (bash sets this automatically)
   
   ### 3. Function Existence Check
   
   The `function_exists` function was modified to handle both shells:
   
   | Bash | Zsh |
   |------|-----|
   | `declare -F $1 > /dev/null` | `typeset -f $1 > /dev/null 2>&1` |
   
   Zsh uses `typeset` instead of `declare` for function introspection. The `2>&1` redirect suppresses potential error messages.
   
   ### 4. Variable Listing for Plugin Discovery
   
   The `common_plugins` variable discovery was updated:
   
   | Bash | Zsh |
   |------|-----|
   | `compgen -v \| grep "^plugin_goals_.*"` | `typeset + \| grep "^plugin_goals_"` |
   
   * Bash uses `compgen -v` to list all variable names
   * Zsh uses `typeset +` to list variable names (the `+` modifier shows only names)
   
   ### 5. Indirect Variable Expansion
   
   When accessing plugin goals dynamically by variable name, different syntax is required:
   
   | Bash | Zsh |
   |------|-----|
   | `${!var_name}` | `${(P)var_name}` |
   
   * Bash uses `${!var_name}` for indirect expansion (dereference)
   * Zsh uses `${(P)var_name}` - the `(P)` flag enables parameter name expansion
   
   The updated code:
   
   ```shell
   local var_value
   if [ "$__MVND_SHELL" = "zsh" ]; then
       var_value="${(P)var_name}"
   else
       var_value="${!var_name}"
   fi
   COMPREPLY=( $(compgen -W "${var_value}" -S ' ' -- ${cur}) )
   ```
   
   ## Summary of Shell Differences
   
   | Feature | Bash | Zsh |
   |---------|------|-----|
   | Function existence check | `declare -F name` | `typeset -f name` |
   | List variables | `compgen -v` | `typeset +` |
   | Indirect variable expansion | `${!varname}` | `${(P)varname}` |
   | Completion system init | Built-in | `autoload -Uz compinit && compinit` |
   | Bash compatibility | N/A | `autoload -Uz bashcompinit && bashcompinit` |
   | Word break characters | Auto-set in `COMP_WORDBREAKS` | Must be manually defined |
   
   ## Usage
   
   The script works automatically in both shells. Simply source it in your shell configuration:
   
   ```shell
   # In ~/.bashrc or ~/.zshrc
   source /path/to/mvnd-bash+zsh-completion.sh
   ```
   


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Re: [PR] Enable completion for both bash and zsh [maven-mvnd]

["gnodet (via GitHub)" <gi...@apache.org>]

gnodet commented on PR #1514:
URL: https://github.com/apache/maven-mvnd/pull/1514#issuecomment-4073080471

   Thanks for the contribution @janweinschenker! The idea of making the completion script work in both bash and zsh is great.
   
   I've opened #1559 which takes a slightly different approach: instead of adding a second script file, it modifies the existing `mvnd-bash-completion.bash` template in-place to auto-detect the shell. This keeps a single script to maintain and integrates with the existing generation pipeline (`CompletionGeneratorTest`).
   
   Key differences from this PR:
   - Single file (no duplication with the existing bash script)
   - Goes through the template so the generator keeps working
   - No global `setopt` calls that could affect user shell preferences
   - No redundant `compinit` (only `bashcompinit` which is needed)
   - `Completion.java` updated to accept `--completion zsh`
   - README updated instead of a separate `.adoc` file
   
   You're credited as co-author on the commit. Would you mind testing #1559 in your zsh environment?


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Re: [PR] Enable completion for both bash and zsh [maven-mvnd]

["janweinschenker (via GitHub)" <gi...@apache.org>]

janweinschenker commented on PR #1514:
URL: https://github.com/apache/maven-mvnd/pull/1514#issuecomment-3766758260

   Hi all, please let me know if anything is missing or needs to be changed.


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Re: [PR] Enable completion for both bash and zsh [maven-mvnd]

["janweinschenker (via GitHub)" <gi...@apache.org>]

janweinschenker commented on PR #1514:
URL: https://github.com/apache/maven-mvnd/pull/1514#issuecomment-4126455888

   Happy to hear this is being picked up :-) 
   
   I'll help with testing of course.


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