Merge pull request #38 from bliutech/22-solver-implement-sympy-simpli…

…fier

22 solver implement sympy simplifier

solver/passes/sympy_pass.py

@@ -0,0 +1,102 @@
+from typing import override
+from parser.ast import (
+    Var,
+    Expr,
+    VarExpr,
+    NotExpr,
+    ParenExpr,
+    AndExpr,
+    OrExpr,
+)
+from parser.visitor import Visitor, RetVisitor
+from parser.parse import Parser
+from parser.lex import Lexer
+
+import sympy
+from sympy.logic.boolalg import And, Or, Not
+
+
+def run_pass(ast: Expr) -> Expr:
+    # Sympy visitor for mapping variable
+    v: SympyMappingVisitor = SympyMappingVisitor()
+    ast.accept(v)
+
+    tv: TranslateToSympy = TranslateToSympy(v.symbols)
+
+    p: sympy.Basic = ast.acceptRet(tv)
+
+    simplifiedExpr: sympy.Basic = sympy.simplify_logic(p)
+    simplifiedStr: str = str(simplifiedExpr)
+
+    l: Lexer = Lexer()
+    l.lex(simplifiedStr)
+
+    pa: Parser = Parser()
+    ast: Expr = pa.parse(l.tokens)
+
+    return ast
+
+
+class SympyMappingVisitor(Visitor):
+    """
+    A visitor that visits each node in the AST and adds Var nodes to the symbolMap.
+    """
+
+    def __init__(self) -> None:
+        self.symbolMap: dict[str, sympy.Symbol] = {}
+
+    @override
+    def visitVar(self, va: Var) -> None:
+        self.symbolMap[va.name] = sympy.Symbol(va.name)
+
+
+class TranslateToSympy(RetVisitor[sympy.Basic]):
+    """
+    A visitor that visits each node in the AST and
+    returns an expression translated to Sympy logic.
+    """
+
+    def __init__(self, symbols: dict[str, sympy.Symbol]) -> None:
+        self.symbols = symbols
+
+    @override
+    def visitVarExpr(self, vex: VarExpr) -> sympy.Basic:
+        first: sympy.Basic = vex.first.acceptRet(self)
+        if vex.second:
+            second: sympy.Basic = vex.second.first.acceptRet(self)
+            if isinstance(vex.second, AndExpr):
+                return And(first, second)
+            elif isinstance(vex.second, OrExpr):
+                return Or(first, second)
+        return first
+
+    @override
+    def visitNotExpr(self, nex: NotExpr) -> sympy.Basic:
+        return Not(nex.first.acceptRet(self))
+
+    @override
+    def visitParenExpr(self, pex: ParenExpr) -> sympy.Basic:
+        return pex.first.acceptRet(self)
+
+    @override
+    def visitAndExpr(self, aex: AndExpr) -> sympy.Basic:
+        pass
+
+    @override
+    def visitOrExpr(self, oex: OrExpr) -> sympy.Basic:
+        pass
+
+    @override
+    def visitVar(self, va: Var) -> sympy.Basic:
+        return self.symbols[va.name]
+
+
+if __name__ == "__main__":
+    prog = "B & A | !A"
+    l: Lexer = Lexer()
+    l.lex(prog)
+
+    p: Parser = Parser()
+    ast: Expr = p.parse(l.tokens)
+
+    run_pass(ast)