Desktop app for visualizing parse tree , abstract syntax tree , action table , parse table for any valid LL1 grammar.
Exp --> Term Exp`
Exp` --> Addop Term Exp` | Epsilon
Addop --> + | -
Term --> Factor Term`
Term` --> Mullop Factor Term` | Epsilon
Mullop --> * | /
Factor --> ID | NUM | ( Exp )
parse table for this grammar
guide for implementing your own grammar
in parsers/grammar.py
in this file you add your rules as classes which inherits from TreeNode (responsible for drawing tree) , and Rule (responsible for generating new rules when this rule takes an input or raise error when the rule can't process the input)
this exp` implementation example:
class ExpDash(TreeNode,Rule):
def __init__(self, treecanvas, level, parent, left, right,):
rules = dict() # dictionary acts like the row of this rule in parse table(maps each item to its corresponding genearated rule)
rules['+'] = [Addop,Term,ExpDash] # corresponds to + entry for exp' in parse table
rules['-'] = [Addop,Term,ExpDash] # corresponds to - entry for exp' in parse table
rules[')'] = [EpsilonTerminal] # corresponds to ) entry for exp' in parse table
rules['$'] = [EpsilonTerminal] # corresponds to $ entry for exp' in parse table
TreeNode.__init__(self,treecanvas,level,parent,left, right, None,'Exp\'', False)
Rule.__init__(self,rule_name= 'Exp\'',rules=rules) # rule_name is for action table
repeat this process for other rules
in parsers/terminals.py
in this file you add your terminals as classes which inherits from TreeNode (responsible for drawing tree) , specify for them pirority if they will partcipate in abstract tree pirority is reversed (ex: + = 2 , * = 1)
this plusTerminal , identifier implementation example:
class plusTerminal(TreeNode):
def __init__(self, treecanvas, level, parent, left, right,):
super().__init__(treecanvas,level,parent,left, right, None,'+', True)
self.pirority = 2
class IDTerminal(TreeNode):
def __init__(self, treecanvas, level, parent, left, right,):
super().__init__(treecanvas,level,parent,left, right, None,'id', True)
self.pirority = 0
def __repr__(self) -> str:
return 'id'
repeat this process for other terminals
in parsers/parser.py
you need to define this tuple
SPLIT_TERMINALS = ('+' , '-' , '*' , '/' , ')' , '(') # tuple which is used to genarate your tokens (split by charachters)
example: input = 'num10+num20-11' and SPLIT_TERMINALS = ('+' , '-')
tokens = ['num10','+','num20','-','11']
for more details about implementation you can take a look at Parser.__parse_input() function which is responsible for generating tokens
in parsers/abstract.py
you need to define this three tuples in AbstractSyntaxAnalyzer class according to your grammar
TERMINALS = (IDTerminal,NumTerminal,plusTerminal,minusTerminal,multiplyTerminal,divisionTerminal) # Terminals which will participate in abstract tree
SEPARATOR = (leftBracketTerminal) # Terminal in which when found start new list of tokens which is treated as single element in old token ex: 2*(3*3) this will make your list = [2,*,[3,*,3]] instead of list = [2,*,3,*,3]
TERMINATOR = (rightBracketTerminal) # Terminal in which End the separtor created list right bracket in my case
in GUI/table.py
define this two list
TERMINALS = [plusTerminal,minusTerminal,leftBracketTerminal,rightBracketTerminal,multiplyTerminal,divisionTerminal,dollarTerminal,IDTerminal,NumTerminal] # list contains all your terminals classes
RULES = [Exp,ExpDash,Addop,Mullop,Factor,Term,TermDash] # list contains all your rules classes
in main.py
line 30
define your parser using your start rule
in my example it's EXP (Start rule class) :
self.__parser = Parser(self.canvas.canvas,Exp)
tk==0.1.0