Rename hook environment variables to be shell agnostic

The environment variables used to pass state from the shell hooks to
EnvironmentCompletionContext were using names from BASH's completion system,
which were meaningless if you're not familiar with writing completion functions
for BASH. Since completion isn't limited to the BASH shell any more, I've
renamed these environment variables to make them more meaningful.

This shouldn't break any existing installations unless hooks have been generated
and copy-pasted into a script. To cover for this case, or an update mid-session,
this change includes a warning message if calling completion with COMP_LINE set.

Resolves #31

Author: stecman

src/EnvironmentCompletionContext.php

@@ -10,11 +10,21 @@ class EnvironmentCompletionContext extends CompletionContext
      */
     public function __construct()
     {
-        $this->commandLine = getenv('COMP_LINE');
-        $this->charIndex = intval(getenv('COMP_POINT'));
+        $this->commandLine = getenv('CMDLINE_CONTENTS');
+        $this->charIndex = intval(getenv('CMDLINE_CURSOR_INDEX'));
 
         if ($this->commandLine === false) {
-            throw new \RuntimeException('Failed to configure from environment; Environment var COMP_LINE not set.');
+            $message = 'Failed to configure from environment; Environment var CMDLINE_CONTENTS not set.';
+
+            if (getenv('COMP_LINE')) {
+                $message .= "\n\nYou appear to be attempting completion using an out-dated hook. If you've just updated,"
+                            . " you probably need to reinitialise the completion shell hook by reloading your shell"
+                            . " profile or starting a new shell session. If you are using a hard-coded (rather than generated)"
+                            . " hook, you will need to update that function with the new environment variable names."
+                            . "\n\nSee here for details: https://github.com/stecman/symfony-console-completion/issues/31";
+            }
+
+            throw new \RuntimeException($message);
         }
     }
 
@@ -25,10 +35,10 @@ public function __construct()
      */
     public function useWordBreaksFromEnvironment()
     {
-        $breaks = getenv('COMP_WORDBREAKS');
+        $breaks = getenv('CMDLINE_WORDBREAKS');
 
         if (!$breaks) {
-            throw new \RuntimeException('Failed to read word breaks from environment; Environment var COMP_WORDBREAKS not set');
+            throw new \RuntimeException('Failed to read word breaks from environment; Environment var CMDLINE_WORDBREAKS not set');
         }
 
         $this->wordBreaks = $breaks;

src/HookFactory.php

@@ -30,7 +30,15 @@ final class HookFactory
         'bash' => <<<'END'
 # BASH completion for %%program_path%%
 function %%function_name%% {
-    export COMP_LINE COMP_POINT COMP_WORDBREAKS;
+
+    # Copy BASH's completion variables to the ones the completion command expects
+    # These line up exactly as the library was originally designed for BASH
+    local CMDLINE_CONTENTS="$COMP_LINE"
+    local CMDLINE_CURSOR_INDEX="$COMP_POINT"
+    local CMDLINE_WORDBREAKS="$COMP_WORDBREAKS";
+
+    export CMDLINE_CONTENTS CMDLINE_CURSOR_INDEX CMDLINE_WORDBREAKS
+
     local RESULT STATUS;
 
     RESULT="$(%%completion_command%%)";
@@ -63,15 +71,11 @@ function %%function_name%% {
         , 'zsh' => <<<'END'
 # ZSH completion for %%program_path%%
 function %%function_name%% {
-    # Emulate BASH's command line contents variable
-    local -x COMP_LINE="$words"
-
-    # Emulate BASH's cursor position variable, setting it to the end of the current word.
-    local -x COMP_POINT
-    (( COMP_POINT = ${#${(j. .)words[1,CURRENT]}} ))
+    local -x CMDLINE_CONTENTS="$words"
+    local -x CMDLINE_CURSOR_INDEX
+    (( CMDLINE_CURSOR_INDEX = ${#${(j. .)words[1,CURRENT]}} ))
 
     local RESULT STATUS
-    local -x COMPOSER_CWD=`pwd`
     RESULT=("${(@f)$( %%completion_command%% )}")
     STATUS=$?;