Parsing the php code

Problem

Given a tokenized PHP file, give me a map from class to list of functions.

Here is same PHP code.

class Foo {
    public $aMemberVar = 'aMemberVar Member Variable';     public$aFuncName = 'aMemberFunc';
 
 
function aMemberFunc() {
        print 'Inside `aMemberFunc()`';
    }
function bob() {
print "hi, Hi am functopm bob2 ";
}
}

class Olivia
{
function say() { print "hi"; }
}
$foo = new Foo;

class bogus ;

Write the code to return the map of the class name to the list of functions.

Answer

This is a very vague question with very little detailed requirements. To solve this problem properly, I made the following assumptions:

• Input is list of tokens after tokenization.
• all the special chars (",', {,}, \,) are separate token

Given the assumptions, we need to examine each token and handle the following cases:

• if token = class, mark the class flag if neither of single/double quotation is non-zero and take the next non-empty string as a class name and add it to class map (if not exists) 
• if token is {, increase left_bracket count by 1.
• if token =  "function" and we are not in single/double quotation, mark function flag to true.
• if token is  } decrease left_bracket by 1
• if token is " decrease double quotation by 1 if it is greater than 1
• if token is ' decrease single quotation by 1 if it is greater than 1
• if token is a word,
• add the word to class map if class flag is True
• add the word to function list of the current class if function flag is True

This question seems to be more of design question than algorithm question.

Here is a solution in python:

	class PhpParser:
	def parse(self, tokens):
	self.left_bracket = 0
	self.is_class = False
	self.function = False
	self.double_quote = False
	self.single_quote = False
	class_map = {}
	current_class = None
	for token in tokens:
	if len(token) == 0:
	continue
	if token == "class":
	self.is_class = True if self.double_quote != True and self.single_quote !=True and self.left_bracket == 0 else False
	elif token == "function":
	self.function = True if self.double_quote != True and self.single_quote !=True else False
	elif token == "{":
	self.left_bracket += 1
	elif token == "}":
	self.left_bracket -= 1
	elif token == "'":
	self.single_quote = False if self.single_quote == True else True
	elif token == '"':
	self.single_quote = False if self.single_quote == True else True
	else:
	# it is string token, process it accordingly.
	if self.is_class == True and token not in class_map:
	class_map[token] = []
	current_class = token
	self.is_class = False
	elif self.function == True and current_class != None:
	class_map[current_class].append(token)
	self.function = False
	return class_map
	parser = PhpParser()
	input = [
	"class", "Foo", "{",
	"public", "$aMemberVar", "=", "'", "aMemberVar", "Member", "Variable", "'",";",
	"public", "$aFuncName", "=", "'","aMemberFunc","'",";",
	"function", "aMemberFunc","(",")", "{",
	"print", "'", "Inside" "`","aMemberFunc","(",")","`","'",";",
	"}",
	"function", "bob","(",")", "{",
	"print", '"',"hi", ",", "Hi", "am", "function", "bob2", '"',";",
	"}",
	"}",
	"class", "Olivia",
	"{",
	"function", "say","(",")", "{", "print", '"',"hi",'"', ";", "}",
	"}",
	"$foo", "=", "new", "Foo", ";",
	"class", "bogus", ";"
	]
	print ("input = {} \n output = {}".format(input, parser.parse(input)))

view raw facebook_php_parser.py hosted with ❤ by GitHub

Practice statistics

 40:00 to write up the complete code.