merged skunkworks into develop.

laravel/database/grammar.php

@@ -0,0 +1,108 @@
+<?php namespace Laravel\Database;
+
+abstract class Grammar {
+
+	/**
+	 * The keyword identifier for the database system.
+	 *
+	 * @var string
+	 */
+	protected $wrapper = '"%s"';
+
+	/**
+	 * Wrap a value in keyword identifiers.
+	 *
+	 * @param  string  $value
+	 * @return string
+	 */
+	public function wrap($value)
+	{
+		// If the value being wrapped contains a column alias, we need to
+		// wrap it a little differently as each segment must be wrapped
+		// and not the entire string. We'll split the value on the "as"
+		// joiner to extract the column and the alias.
+		if (strpos(strtolower($value), ' as ') !== false)
+		{
+			$segments = explode(' ', $value);
+
+			return $this->wrap($segments[0]).' AS '.$this->wrap($segments[2]);
+		}
+
+		// Expressions should be injected into the query as raw strings,
+		// so we do not want to wrap them in any way. We'll just return
+		// the string value from the expression to be included.
+		if ($value instanceof Expression) return $value->get();
+
+		// Since columns may be prefixed with their corresponding table
+		// name so as to not make them ambiguous, we will need to wrap
+		// the table and the column in keyword identifiers.
+		foreach (explode('.', $value) as $segment)
+		{
+			if ($segment == '*')
+			{
+				$wrapped[] = $segment;
+			}
+			else
+			{
+				$wrapped[] = sprintf($this->wrapper, $segment);
+			}
+		}
+
+		return implode('.', $wrapped);
+	}
+
+	/**
+	 * Create query parameters from an array of values.
+	 *
+	 * <code>
+	 *		Returns "?, ?, ?", which may be used as PDO place-holders
+	 *		$parameters = $grammar->parameterize(array(1, 2, 3));
+	 *
+	 *		// Returns "?, "Taylor"" since an expression is used
+	 *		$parameters = $grammar->parameterize(array(1, DB::raw('Taylor')));
+	 * </code>
+	 *
+	 * @param  array   $values
+	 * @return string
+	 */
+	final public function parameterize($values)
+	{
+		return implode(', ', array_map(array($this, 'parameter'), $values));
+	}
+
+	/**
+	 * Get the appropriate query parameter string for a value.
+	 *
+	 * <code>
+	 *		// Returns a "?" PDO place-holder
+	 *		$value = $grammar->parameter('Taylor Otwell');
+	 *
+	 *		// Returns "Taylor Otwell" as the raw value of the expression
+	 *		$value = $grammar->parameter(DB::raw('Taylor Otwell'));
+	 * </code>
+	 *
+	 * @param  mixed   $value
+	 * @return string
+	 */
+	final public function parameter($value)
+	{
+		return ($value instanceof Expression) ? $value->get() : '?';
+	}
+
+	/**
+	 * Create a comma-delimited list of wrapped column names.
+	 *
+	 * <code>
+	 *		// Returns ""Taylor", "Otwell"" when the identifier is quotes
+	 *		$columns = $grammar->columnize(array('Taylor', 'Otwell'));
+	 * </code>
+	 *
+	 * @param  array   $columns
+	 * @return string
+	 */
+	final public function columnize($columns)
+	{
+		return implode(', ', array_map(array($this, 'wrap'), $columns));
+	}
+
+}