added for and while loop in language

basic.py

@@ -34,7 +34,11 @@
  "if",
  "then",
  "elif",
- "else"
+ "else",
+ "for",
+ "to",
+ "step",
+ "while"
 ]
 
 #----------------------errors----------------------#
@@ -315,7 +319,26 @@ def __init__(self,cases,else_case):
  self.pos_start=self.cases[0][0].pos_start
  self.pos_end=(self.else_case or self.cases[-1][0]).pos_end 
 
-
+class ForNode: 
+ def __init__(self,var_name_tok,start_value_node,end_value_node,step_value_node,body_node,should_return_null):
+ self.var_name_tok=var_name_tok
+ self.start_value_node=start_value_node
+ self.end_value_node=end_value_node
+ self.step_value_node=step_value_node
+ self.body_node=body_node
+ self.should_return_null=should_return_null
+
+ self.pos_start=self.var_name_tok.pos_start
+ self.pos_end=self.body_node.pos_end
+
+class WhileNode:
+ def __init__(self,condition_node,body_node,should_return_null=None):
+ self.condition_node=condition_node
+ self.body_node=body_node
+ self.should_return_null=should_return_null
+
+ self.pos_start=self.condition_node.pos_start
+ self.pos_end=self.body_node.pos_end
 
 #----------------------parser result----------------------#
 
@@ -376,6 +399,7 @@ def factor(self):
  res.register_advancement()
  self.advance()# does not know what it does
  return res.success(NumberNodes(tok))
+
  elif tok.type == TT_LPAREN:
  res.register_advancement()
  self.advance()
@@ -390,7 +414,17 @@ def factor(self):
  elif tok.matches(TT_KEYWORD,"if"):
  if_expr=res.register(self.if_expr())
  if res.error: return res
- return res.success(if_expr) 
+ return res.success(if_expr) 
+
+ elif tok.matches(TT_KEYWORD,"for"):
+ for_expr=res.register(self.for_expr())
+ if res.error: return res
+ return res.success(for_expr) 
+
+ elif tok.matches(TT_KEYWORD,"while"):
+ while_expr=res.register(self.while_expr())
+ if res.error: return res
+ return res.success(while_expr) 
 
  return res.failure(InvalidSyntaxError(tok.pos_start,tok.pos_end,"Expected int or float, Indentifier, '+','-','('"))
 
@@ -441,6 +475,75 @@ def if_expr(self):
 
  return res.success(IfNode(cases,else_case))
 
+ def for_expr(self):
+ res=ParseResult()
+
+ if not self.current_tok.matches(TT_KEYWORD,"for"):
+ return res.failure(InvalidSyntaxError(self.current_tok.pos_start,self.current_tok.pos_end,"Expected 'for'"))
+ res.register_advancement()
+ self.advance()
+
+ if self.current_tok.type != TT_INDENTIFIER:
+ return res.failure(InvalidSyntaxError(self.current_tok.pos_start,self.current_tok.pos_end,"Expected identifier"))
+ var_name=self.current_tok
+ res.register_advancement()
+ self.advance()
+
+ if self.current_tok.type != TT_EQ:
+ return res.failure(InvalidSyntaxError(self.current_tok.pos_start,self.current_tok.pos_end,"Expected '='"))
+ res.register_advancement()
+ self.advance()
+
+ start_value=res.register(self.expr())
+ if res.error: return res
+
+ if not self.current_tok.matches(TT_KEYWORD,"to"):
+ return res.failure(InvalidSyntaxError(self.current_tok.pos_start,self.current_tok.pos_end,"Expected 'to'"))
+ res.register_advancement()
+ self.advance()
+
+ end_value=res.register(self.expr())
+ if res.error: return res
+
+ if self.current_tok.matches(TT_KEYWORD,"step"):
+ res.register_advancement()
+ self.advance()
+
+ step_value=res.register(self.expr())
+ if res.error: return res
+ else:
+ step_value=None
+
+ if not self.current_tok.matches(TT_KEYWORD,"then"):
+ return res.failure(InvalidSyntaxError(self.current_tok.pos_start,self.current_tok.pos_end,"Expected 'then'"))
+ res.register_advancement()
+ self.advance()
+
+ body=res.register(self.expr())
+ if res.error: return res
+
+ return res.success(ForNode(var_name,start_value,end_value,step_value,body,True))
+
+ def while_expr(self):
+ res=ParseResult()
+
+ if not self.current_tok.matches(TT_KEYWORD,"while"):
+ return res.failure(InvalidSyntaxError(self.current_tok.pos_start,self.current_tok.pos_end,"Expected 'while'"))
+ res.register_advancement()
+ self.advance()
+
+ condition=res.register(self.expr())
+ if res.error: return res
+
+ if not self.current_tok.matches(TT_KEYWORD,"then"):
+ return res.failure(InvalidSyntaxError(self.current_tok.pos_start,self.current_tok.pos_end,"Expected 'then'"))
+ res.register_advancement()
+ self.advance()
+
+ body=res.register(self.expr())
+ if res.error: return res
+
+ return res.success(WhileNode(condition,body,True))
 
  def term(self):
  return self.bin_op(self.factor,(TT_MUL,TT_DIV))
@@ -730,7 +833,41 @@ def visit_IfNode(self,node,context):
  else_value=res.register(self.visit(node.else_case,context))
  if res.error:return res
  return res.success(else_value) 
- return res.success(None) 
+ return res.success(None) 
+
+ def visit_ForNode(self,node,context):
+ res=RTResult()
+
+ start_value=res.register(self.visit(node.start_value_node,context))
+ if res.error:return res
+ end_value=res.register(self.visit(node.end_value_node,context))
+ if res.error:return res
+ if node.step_value_node:
+ step_value=res.register(self.visit(node.step_value_node,context))
+ if res.error:return res
+ else:
+ step_value=Number(1)
+ i=start_value.value
+ if step_value.value >= 0:
+ condition=lambda:i<end_value.value
+ else:
+ condition=lambda:i>end_value.value
+ while condition():
+ context.symbol_table.set(node.var_name_tok.value,Number(i))
+ i+=step_value.value
+ res.register(self.visit(node.body_node,context))
+ if res.error:return res
+ return res.success(None)
+
+ def visit_WhileNode(self,node,context):
+ res=RTResult()
+ while True:
+ condition=res.register(self.visit(node.condition_node,context))
+ if res.error:return res
+ if not condition.is_true():break
+ res.register(self.visit(node.body_node,context))
+ if res.error:return res
+ return res.success(None) 
 
 #----------------------Runs----------------------# 
 

grammar.txt

@@ -12,4 +12,8 @@ factor : INT|FLOAT|IDENTIFIER
  :if-expr
 if-expr:KEYWORD:if expr KEYWORD:then expr
  (KEYWORD:elif expr KEYWORD:then expr)*
- (KEYWORD:else expr)?
+ (KEYWORD:else expr)?
+
+for-expr :KEYWORD:for IDENTIFIER EO expr KEYWORD:to expr
+ (KEYWORD:step expr)? KEYWORD:then expr
+while-expr:KEYWORD:while expr KEYWORD:then expr