Work on lalr grammar

Author: albop

src/dolang/formulas.lark

@@ -0,0 +1,50 @@
+?start: formula
+
+equation_block: _NEWLINE? (equation) (_NEWLINE equation )* _NEWLINE?
+
+?equation: equality | formula
+
+equality: formula "=" formula
+
+?formula: sum
+
+?sum: product
+    | sum "+" product   -> add
+    | sum "-" product   -> sub
+    | "-" product         -> neg
+?product: atom|pow
+    | product "*" (atom|pow)  -> mul
+    | product "/" (atom|pow)  -> div
+?pow: atom _POW atom -> pow
+
+_POW: "^" | "**"
+
+?atom: NUMBER           -> number
+        | constant            
+        | "(" sum ")"
+        | call
+        | variable
+
+!constant: NAME -> constant
+
+variable: cname  "[" date_index  "]" -> variable
+
+!cname: NAME -> name
+
+?date_index: "t" [SIGNED_INT2] -> date
+    
+?call: cname "(" formula ")" -> call
+
+SIGNED_INT2: ("+"|"-") INT
+
+_NEWLINE: NEWLINE
+UNICODE_LETTER: /[^\W\d_\$]/
+NAME: UNICODE_LETTER ("_"|UNICODE_LETTER|DIGIT)*
+
+%import common.SIGNED_INT
+%import common.DIGIT
+%import common.INT
+%import common.NUMBER
+%import common.WS_INLINE
+%import common.NEWLINE
+%ignore WS_INLINE

src/dolang/grammar.py

@@ -34,6 +34,12 @@
 
 grammar_0 = open(DATA_PATH, "rt", encoding="utf-8").read()
 
+F_PATH = os.path.join(DIR_PATH, "formulas.lark")
+
+grammar_f = open(F_PATH, "rt", encoding="utf-8").read()
+
+
+
 # from .grammar_lark import grammar_0
 
 from lark.lark import Lark
@@ -50,6 +56,27 @@
     ],
 )
 
+### replaces date with 0 when missing
+class TimeFixer(Transformer):
+
+    def date(self, args):
+        if args[0] is None:
+            return Tree("date", [Token("NUMBER", "0")])
+        else:
+            return Tree("date", [Token("NUMBER", args[0])])
+
+
+parser_f = Lark(
+    grammar_f,
+    start=[
+        "formula",
+        "equation_block"
+    ],
+    parser="lalr",
+    strict=True,
+    transformer=TimeFixer()
+)
+
 
 def parse_string(text, start=None):