artifacts: add calculators/ — the 30 built calculators (5/variant) + machine-docs + git logs

calculators/builder-adversary-min/run-01/calc/parser.py

@@ -0,0 +1,113 @@
+"""Recursive-descent parser for arithmetic expressions.
+
+AST node shapes:
+    Num(value)               — numeric literal; value is int or float
+    BinOp(op, left, right)   — binary op; op in {'+', '-', '*', '/'}
+    Unary(op, operand)       — unary op; op is '-'
+
+Grammar (lowest to highest precedence):
+    expr    → term (('+' | '-') term)*
+    term    → unary (('*' | '/') unary)*
+    unary   → '-' unary | primary
+    primary → NUMBER | '(' expr ')'
+"""
+
+from dataclasses import dataclass
+from typing import Union
+
+
+class ParseError(Exception):
+    pass
+
+
+@dataclass
+class Num:
+    value: Union[int, float]
+
+    def __repr__(self):
+        return f"Num({self.value!r})"
+
+
+@dataclass
+class BinOp:
+    op: str
+    left: object
+    right: object
+
+    def __repr__(self):
+        return f"BinOp({self.op!r}, {self.left!r}, {self.right!r})"
+
+
+@dataclass
+class Unary:
+    op: str
+    operand: object
+
+    def __repr__(self):
+        return f"Unary({self.op!r}, {self.operand!r})"
+
+
+Node = Union[Num, BinOp, Unary]
+
+
+def parse(tokens: list) -> Node:
+    """Parse a token list produced by tokenize() and return the AST root."""
+    if not tokens:
+        raise ParseError("Empty token list")
+    p = _Parser(tokens)
+    tree = p.expr()
+    if p.current().kind != 'EOF':
+        raise ParseError(f"Unexpected token {p.current()!r} after expression")
+    return tree
+
+
+class _Parser:
+    def __init__(self, tokens):
+        self._tokens = tokens
+        self._pos = 0
+
+    def current(self):
+        return self._tokens[self._pos]
+
+    def consume(self, kind=None):
+        tok = self.current()
+        if kind is not None and tok.kind != kind:
+            raise ParseError(f"Expected {kind!r}, got {tok!r}")
+        self._pos += 1
+        return tok
+
+    def expr(self):
+        left = self.term()
+        while self.current().kind in ('PLUS', 'MINUS'):
+            tok = self.consume()
+            op = '+' if tok.kind == 'PLUS' else '-'
+            right = self.term()
+            left = BinOp(op, left, right)
+        return left
+
+    def term(self):
+        left = self.unary()
+        while self.current().kind in ('STAR', 'SLASH'):
+            tok = self.consume()
+            op = '*' if tok.kind == 'STAR' else '/'
+            right = self.unary()
+            left = BinOp(op, left, right)
+        return left
+
+    def unary(self):
+        if self.current().kind == 'MINUS':
+            self.consume()
+            return Unary('-', self.unary())
+        return self.primary()
+
+    def primary(self):
+        tok = self.current()
+        if tok.kind == 'NUMBER':
+            self.consume()
+            return Num(tok.value)
+        if tok.kind == 'LPAREN':
+            self.consume()
+            node = self.expr()
+            self.consume('RPAREN')
+            return node
+        raise ParseError(f"Unexpected token {tok!r}")