telugu_parser.php

<?php

// telugu_parser.php primarily deals with splitting an input string
// into a series of logical characters 
// contact Siva.Jasthi@metrostate.edu for any clarifications on
// telugu processing logic used in these functions.

function stripSpacesTelugu($log_chars) {
	$code_points = parseToCodePoints(implode($log_chars));

	$build = array();
	$build_i = 0;
	for($i=0; $i < count($code_points); $i++) {
		if(strcmp($log_chars[$i], " ") == 0) continue;

		else {
			$build[$build_i++] = $log_chars[$i];
			if(isHalant(end($code_points[$i]) && $i + 1 < count($code_points))) {
				if($code_points[$i+1] == 32) { // if the next character is a space...
					$build[$build_i][count($build[$build_i])] = json_decode("\u200c");
				}
			}
		}
	}
	return $build;
}

// $word expects a single utf-8 encoded word
// returns a 2 dimensional array, representing the unicoded logical characters of the word
function parseToCodePoints($word) {
	$word_array = explode_telugu(json_encode($word));
	$i = 0;
	$logical_chars = array();
	$ch_buffer = array();

	while( $i < count($word_array) ) {
		$current_ch = $word_array[$i++];
		$ch_buffer[count($ch_buffer)] = $current_ch;
		if( $i == count($word_array) ) {
			$logical_chars[count($logical_chars)] = $ch_buffer;
			continue;
		}
		$next_ch = $word_array[$i];
		if(isDependent($next_ch)) {
			$ch_buffer[count($ch_buffer)] = $next_ch;
			$i++;
			$logical_chars[count($logical_chars)] = $ch_buffer;
			$ch_buffer = array();
			continue;
		}
		if(isHalant($current_ch)) {
			if(isConsonant($next_ch)) {
				if($i < count($word_array)) {
					continue;
				}
				$ch_buffer[count($ch_buffer)] = $current_ch;
			}
			$logical_chars[count($logical_chars)] = $ch_buffer;
			$ch_buffer = array();
			continue;
		} else if(isConsonant($current_ch)) {
			if(isHalant($next_ch) || isDependentVowel($next_ch)) {
				if($i < count($word_array)) {
					continue;
				}
				$ch_buffer[count($ch_buffer)] = $current_ch;
			}
			$logical_chars[count($logical_chars)] = $ch_buffer;
			$ch_buffer = array();
			continue;
		} else if(isVowel($current_ch)) {
			if(isDependentVowel($next_ch)) {
				$ch_buffer[count($ch_buffer)] = $next_ch;
				$i++;
			}
			$logical_chars[count($logical_chars)] = $ch_buffer;
			$ch_buffer = array();
			continue;
		}
		$logical_chars[count($logical_chars)] = $ch_buffer;
		$ch_buffer = array();
	}

	return $logical_chars;
}

// returns a 2d array of the logical characters, but using Telugu characters
function parseToLogicalCharacters($word) {
	if(is_array($word)) {
		for($i=0; $i < count($word); $i++)
			$word[$i] = parseToCharacter($word[$i]);
		return $word;
	}
	else return parseToLogicalCharacters(parseToCodePoints($word));
}

function parseToCharacter($logical_char) {
	$telugu_char = "";
	foreach($logical_char as $char) {
		if(isTelugu($char))	$telugu_char .= sprintf("\\u%'04s", dechex($char));
		else return chr($char);
	}
	return json_decode('"'.$telugu_char.'"');
}

function explode_telugu($to_explode) {
	// POS //
	$pos=0;
	$e_pos=0;
	$exploded = array();
	while($pos < strlen($to_explode) - 1) {
		if(strcmp($to_explode[$pos], "\"") == 0) {
			$pos++;
			continue;
		}
		if(strcmp($to_explode[$pos], "\\") == 0) { // if the the character in question is a slash...
			if(strcmp($to_explode[$pos + 1], "u") == 0) { // ...followed by a u...
				// PHP7 no longer convert 0x strings to numbers automatically
				//$char = 0 + ("0x" . substr($to_explode, $pos + 2, 4)); // worked in old version of php
				$char = intval(substr($to_explode, $pos + 2, 4), 16); // convert to a number
				if(isTelugu($char)) {
					// if it matches, add it as a character, bump the counter up by six, and continue
					$exploded[$e_pos++] = $char;
					$pos += 6;
					continue;
				}
			}
		}
		$exploded[$e_pos++] = ord($to_explode[$pos++]);
	}

	// remove hidden char space 8204
	if (($key = array_search('8204', $exploded)) !== false) {
		unset($exploded[$key]);
	}
	$exploded = array_values(array_filter($exploded));
	
	return $exploded;
}

function isConsonant($ch) {
	return ( $ch >= 0x0c15 && $ch <= 0x0c39 );
}

function isDependentVowel($ch) {
	return ( $ch >= 0x0c3e && $ch <= 0x0c4c );
}

function isDependent($ch) {
	return ( ($ch == 0x0c01) || ($ch == 0x0c02) || ($ch == 0x0c03) );
}

function isVowel($ch) {
	return ($ch >= 0x0c05 && $ch <= 0x0c14);
}

function isHalant($ch) {
	return $ch == 0x0c4d;
}

function isTeluguNumber($ch) {
	return ($ch >= 0x0c66 && $ch <= 0x0c6f);
}

// this function is not perfect: there are gaps in the Telugu unicode table,
// so it is theoretically possible to get a false positive. However, other than
// intentionally feeding this function bad data, there's no practical way to get
// that false positive, and nothing harmful would happen if you did
function isTelugu($ch) {
	return ( $ch >= 0x0c00 && $ch <= 0x0c7f ) || ( $ch == 0x200c );
}

function is_blank_Telugu($hexVal){
	$is_blank = false;
	$blankArray = array("c00","c01","c02","c03","c0d","c11","c29","c34");
	if(in_array($hexVal, $blankArray)){
		return true;
	}
	return $is_blank;
}