/*
 * Copyright (C)2005-2012 Haxe Foundation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

/**
	The EReg class represents regular expressions.
	
	While basic usage and patterns consistently work across platforms, some more
	complex operations may yield different results. This is a necessary trade-
	off to retain a certain level of performance.
	
	EReg instances can be created by calling the constructor, or with the
	special syntax ~/pattern/modifier
	
	EReg instances maintain an internal state, which is affected by several of
	its methods.
	
	A detailed explanation of the supported operations is available at
	http://haxe.org/doc/cross/regexp
**/
class EReg {

	/**
		Creates a new regular expression with pattern [r] and modifiers [opt].
		
		This is equivalent to the shorthand syntax ~/r/opt
		
		If [r] or [opt] are null, the result is unspecified.
	**/
	public function new( r : String, opt : String ) {
		throw "Regular expressions are not implemented for this platform";
	}

	/**
		Tells if [this] regular expression matches String [s].
		
		This method modifies the internal state.
		
		If [s] is null, the result is unspecified.
	**/
	public function match( s : String ) : Bool {
		return false;
	}

	/**
		Returns the matched sub-group [n] of [this] EReg.
		
		This method should only be called after [this].match() or
		[this].matchSub(), and then operates on the String of that operation.
		
		The index [n] corresponds to the n-th set of parentheses in the pattern
		of [this] EReg. If no such sub-group exists, an exception is thrown.
		
		If [n] equals 0, the whole matched substring is returned.
	**/
	public function matched( n : Int ) : String {
		return null;
	}

	/**
		Returns the part to the left of the last matched substring.
		
		If the most recent call to [this].match() or [this].matchSub() did not
		match anything, the result is unspecified.
		
		If the global g modifier was in place for the matching, only the
		substring to the left of the leftmost match is returned.
		
		The result does not include the matched part.
	**/
	public function matchedLeft() : String {
		return null;
	}

	/**
		Returns the part to the right of the last matched substring.
		
		If the most recent call to [this].match() or [this].matchSub() did not
		match anything, the result is unspecified.
		
		If the global g modifier was in place for the matching, only the
		substring to the right of the leftmost match is returned.
		
		The result does not include the matched part.
	**/
	public function matchedRight() : String {
		return null;
	}

	/**
		Returns the position and length of the last matched substring, within
		the String which was last used as argument to [this].match() or
		[this].matchSub().
		
		If the most recent call to [this].match() or [this].matchSub() did not
		match anything, the result is unspecified.
		
		If the global g modifier was in place for the matching, the position and
		length of the leftmost substring is returned.
	**/
	public function matchedPos() : { pos : Int, len : Int } {
		return null;
	}

	/**
		Tells if [this] regular expression matches a substring of String [s].
		
		This function expects [pos] and [len] to describe a valid substring of
		[s], or else the result is unspecified. To get more robust behavior,
		[this].matchSub(s.substr(pos,len)) can be used instead.
		
		This method modifies the internal state.
		
		If [s] is null, the result is unspecified.
	**/
	public function matchSub( s : String, pos : Int, len : Int = 0):Bool {
		return false;
	}

	/**
		Splits String [s] at all substrings [this] EReg matches.
		
		If a match is found at the start of [s], the result contains a leading
		empty String "" entry.
		
		If a match is found at the end of [s], the result contains a trailing
		empty String "" entry.
		
		If two matching substrings appear next to each other, the result
		contains the empty String "" between them.
		
		By default, this method splits [s] into two parts at the first matched
		substring. If the global g modifier is in place, [s] is split at each
		matched substring.
		
		If [s] is null, the result is unspecified.
	**/
	public function split( s : String ) : Array<String> {
		return null;
	}

	/**
		Replaces the first substring of [s] which [this] EReg matches with [by].
		
		If [this] EReg does not match any substring, the result is [s].
		
		By default, this method replaces only the first matched substring. If
		the global g modifier is in place, all matched substrings are replaced.
		
		If [by] contains [$1] to [$9], the digit corresponds to number of a
		matched sub-group and its value is used instead. If no such sub-group
		exists, the replacement is unspecified. The string [$$] becomes [$].
		
		If [s] or [by] are null, the result is unspecified.
	**/
	public function replace( s : String, by : String ) : String {
		return null;
	}

	/**
		For each occurence of the pattern in the string [s], the function [f] is called and
		can return the string that needs to be replaced. All occurences are matched anyway,
		and setting the [g] flag might cause some incorrect behavior on some platforms.
	**/
	public function map( s : String, f : EReg -> String ) : String {
		var buf = new StringBuf();
		while( true ) {
			if( !match(s) )
				break;
			buf.add(matchedLeft());
			buf.add(f(this));
			s = matchedRight();
		}
		buf.add(s);
		return buf.toString();
	}
}