Extract completion handler input to CompletionContext

The CompletionHandler class was handling both completion and setting up the
command/words to complete for. CompletionHandler now takes a CompletionContext
in its constructor, which provides the command and words to complete for.

Additionally:

* Replaced use of the COMP_WORDBREAKS variable with a set of break characters
  more suited to parsing Symfony console application command-lines. This was
  needed for the colon character fix from #1 to work properly, as previously
  ':' was still in COMP_WORDBREAKS so was used to split a command up.
* Added unit tests for CompletionContext

Author: stecman

src/Stecman/Component/Symfony/Console/BashCompletion/CompletionCommand.php

@@ -53,7 +53,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
         if ( $input->getOption('genhook') ) {
             $output->write( $handler->generateBashCompletionHook($input->getOption('program')), true );
         } else {
-            $handler->configureFromEnvironment();
+            $handler->setContext(new EnvironmentCompletionContext());
             $output->write($this->runCompletion(), true);
         }
     }

src/Stecman/Component/Symfony/Console/BashCompletion/CompletionContext.php

@@ -0,0 +1,197 @@
+<?php
+
+
+namespace Stecman\Component\Symfony\Console\BashCompletion;
+
+
+class CompletionContext
+{
+    /**
+     * COMP_WORDS
+     * An array consisting of the individual words in the current command line.
+     * @var array|null
+     */
+    protected $words = null;
+
+    /**
+     * COMP_CWORD
+     * The index in COMP_WORDS of the word containing the current cursor position.
+     * @var int
+     */
+    protected $wordIndex = null;
+
+    /**
+     * COMP_LINE
+     * The current contents of the command line.
+     * @var string
+     */
+    protected $commandLine;
+
+    /**
+     * COMP_POINT
+     * The index of the current cursor position relative to the beginning of the
+     * current command. If the current cursor position is at the end of the current
+     * command, the value of this variable is equal to the length of COMP_LINE.
+     * @var int
+     */
+    protected $charIndex = 0;
+
+    /**
+     * COMP_WORDBREAKS
+     * Characters that $commandLine should be split on to get a list of words in a command
+     * @var string
+     */
+    protected $wordBreaks = "'\"()= \t\n";
+
+    /**
+     * @param string $commandLine
+     */
+    public function setCommandLine($commandLine)
+    {
+        $this->commandLine = $commandLine;
+        $this->reset();
+    }
+
+    /**
+     * @return string
+     */
+    public function getCommandLine()
+    {
+        return $this->commandLine;
+    }
+
+    public function getCurrentWord()
+    {
+        if (isset($this->words[$this->wordIndex])) {
+            return $this->words[$this->wordIndex];
+        }
+
+        return '';
+    }
+
+    public function getWordAtIndex($index)
+    {
+        if (isset($this->words[$index])) {
+            return $this->words[$index];
+        }
+
+        return '';
+    }
+
+    /**
+     * @return array
+     */
+    public function getWords()
+    {
+        if ($this->words === null) {
+            $this->splitCommand();
+        }
+
+        return $this->words;
+    }
+
+    /**
+     * @return int
+     */
+    public function getWordIndex()
+    {
+        if ($this->wordIndex === null) {
+            $this->splitCommand();
+        }
+
+        return $this->wordIndex;
+    }
+
+    /**
+     * @return int
+     */
+    public function getCharIndex()
+    {
+        return $this->charIndex;
+    }
+
+    /**
+     * @param $index
+     */
+    public function setCharIndex($index)
+    {
+        $this->charIndex = $index;
+        $this->reset();
+    }
+
+    /**
+     * @param string $charList
+     */
+    public function setWordBreaks($charList)
+    {
+        $this->wordBreaks = $charList;
+    }
+
+    /**
+     * Split commandLine into words using wordBreaks
+     * @return array
+     */
+    protected function splitCommand()
+    {
+        $this->words = array();
+        $this->wordIndex = null;
+        $cursor = 1;
+
+        $breaks = preg_quote($this->wordBreaks);
+
+        if (!preg_match_all("/([^$breaks]*)([$breaks]*)/", $this->commandLine, $matches)) {
+            return;
+        }
+
+        // Groups:
+        // 1: Word
+        // 2: Break characters
+        foreach ($matches[0] as $index => $wholeMatch) {
+
+            // Determine which word the cursor is in
+            $cursor += strlen($wholeMatch);
+            $word = $matches[1][$index];
+
+            if ($this->wordIndex === null && $cursor >= $this->charIndex) {
+                $this->wordIndex = $index;
+
+                // Find the cursor position relative to the end of the word
+                $cursorWordOffset = $this->charIndex - ($cursor - strlen($matches[2][$index]) - 1);
+
+                if ($cursorWordOffset < 0) {
+
+                    // Cursor is inside the word - truncate the word at the cursor
+                    // (This emulates normal BASH completion behaviour I've observed, though I'm not entirely sure if it's useful)
+                    $word = substr($word, 0, strlen($word) + $cursorWordOffset);
+
+                } else if ($cursorWordOffset > 0) {
+
+                    // Cursor is in the break-space after the word
+                    // Push an empty word at the cursor
+                    $this->wordIndex++;
+                    $this->words[] = $word;
+                    $this->words[] = '';
+                    continue;
+                }
+            }
+
+            if ($word !== '') {
+                $this->words[] = $word;
+            }
+        }
+
+        if ($this->wordIndex > count($this->words) - 1) {
+            $this->wordIndex = count($this->words) - 1;
+        }
+    }
+
+    /**
+     * Reset the computed words so that $this->splitWords is forced to run again
+     */
+    protected function reset()
+    {
+        $this->words = null;
+        $this->wordIndex = null;
+    }
+
+}